patient and staff radiological protection in cardiology (icrp) and staff radiological protection...

DRAFT REPORT FOR CONSULTATION

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ICRP ref 4818-2733-7736 1 May 20, 2011 2

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Annals of the ICRP 5

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ICRP PUBLICATION XXX 8

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Patient and Staff Radiological 11

Protection in Cardiology 12

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Full Members: Claire Cousins (Chair) 17

Donald Miller (Co-Chair) 18

Guglielmo Bernardi 19

Madan Rehani 20

Peter Schofield 21

Eliseo Vano 22

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Corresponding Members: Bernhard Geiger 25

Philip Heintz 26

Renato Padovani 27

Kui-Hian Sim 28

Andrew J. Einstein 29

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Contents 32

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Abstract 34

35

Preface 36

37

Executive Summary 38

39

Recommendations 40

41

Glossary 42

43

1. Introduction 44

45

2. The Biological Effects of Radiation 46

47

3. Clinical Examples of Deterministic Injury after 48

Fluoroscopically Guided Cardiac Procedures 49

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4. Principles of Radiological protection for Patients and Staff 51

52

5. Managing Patient Dose in Fluoroscopically Guided 53

Interventions 54

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6. Radiation Doses and Protection of Staff during Interventional 56

Fluoroscopy 57

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7. Radiological Protection for Nuclear Cardiology 59

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8. Radiological Protection for Cardiac CT 61

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9. Radiological protection Training for Interventional 63

Fluoroscopy 64

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10. Quality Assurance Programmes 66

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Patient and Staff Radiological 69

Protection in Cardiology 70

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ICRP PUBLICATION XXX 72

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Approved by the Commission in Xxxxxxx 20XX 74

75 Abstract- Cardiac nuclear medicine, cardiac CT, percutaneous coronary 76

interventions and electrophysiology procedures are increasing in number and 77

account for an important share of patient radiation exposure in medicine. Complex 78

percutaneous coronary interventions and cardiac electrophysiology procedures are 79

associated with high radiation doses. These procedures can result in patient skin 80

doses high enough to cause radiation injury and, in children, an increased risk of 81

cancer. Treatment of congenital heart disease in children is of particular concern. 82

Additionally, staff in cardiac catheterization laboratories may receive high radiation 83

doses if radiological protection tools are not used properly. 84

The Commission has provided recommendations for radiological protection 85

during fluoroscopically guided interventions in ICRP Publication 85, for 86

radiological protection in CT in ICRP Publications 87 and 102, and for training in 87

radiological protection in ICRP Publication 113 (ICRP 2000a,b, 2007, 2009). This 88

report is focused specifically on cardiology, and brings together information relevant 89

to cardiology from the Commission‘s published documents. There is emphasis on 90

those imaging procedures and interventions specific to cardiology. The material and 91

recommendations in the current document have been updated to reflect the most 92

recent recommendations of the Commission. 93

This report provides guidance to assist the cardiologist with justification and 94

optimization of cardiac CT studies, cardiac nuclear medicine studies and 95

fluoroscopically guided cardiac interventions. It includes discussions of the 96

biological effects of radiation, principles of radiological protection, protection of 97

staff during fluoroscopically guided interventions, radiological protection training 98

and establishment of a quality assurance programme for cardiac imaging and 99

intervention. 100

Because tissue injury, principally skin injury, is a risk for fluoroscopically 101

guided interventions, particular attention is devoted to clinical examples of 102

radiation-related skin injuries from cardiac interventions, methods to reduce patient 103

radiation dose, training recommendations, and quality assurance programs for 104

interventional fluoroscopy. 105

© 2011 ICRP Published by Elsevier Ltd. All rights reserved. 106

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Keywords: Cardiology, Computed Tomography, Nuclear Medicine, Cardiac 108

Catheterization, Radiological Protection 109

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PREFACE 112

113

Over the years, The International Commission on Radiological Protection (ICRP) 114

referred to below as ‗the Commission‘, has issued a number of reports that provide 115

advice on radiological protection and safety in medicine. ICRP Publication 105 is a 116

general overview of this area (ICRP, 2007a). These reports summarize the general 117

principles of radiological protection and provide advice on the application of these 118

principles to the various uses of ionising radiation in medicine. 119

Some previous reports have dealt in part with issues relevant to cardiology and 120

have appeared in print as Publications 85, 87, 102 and 113 (ICRP, 2000a,b, 2007b, 121

2009) and Supporting Guidance 2 (ICRP, 2001). The present report continues this 122

series of concise and focused documents. 123

In cardiology, patient radiation exposure is due to nuclear medicine, CT, 124

percutaneous coronary interventions and electrophysiology procedures. This rapidly 125

expanding field of medicine, both in numbers and complexity, requires guidance for 126

practitioners. 127

At their meeting in Beijing in 2004, the Commission decided that there would be 128

value in developing guidance on radiological protection for cardiologists. Due to a 129

variety of other priorities, work on the document was interrupted for a time and 130

resumed in earnest in 2010. 131

The membership of the Task Group was as follows: 132

133

C. Cousins (Chair) D.L. Miller (Co-Chair) G. Bernardi

M.M. Rehani P. Schofield (1) E. Vañó

134

Corresponding members were: 135

136

(2) B. Geiger P. Heintz R. Padovani

K.-H. Sim A.J. Einstein

137

In addition, Jacques Lochard and John Boice, Main Commission members, made 138

important contributions as critical reviewers. 139

The membership of Committee 3 during the period of final preparation of this 140

report was: 141

142

E. Vañó (Chair) M. M. Rehani (Secretary) M.R. Baeza

J.M. Cosset L.T. Dauer I. Gusev

J.W. Hopewell P.-L. Khong P. Ortiz López

S. Mattson D.L. Miller (3) K. Åhlström

Riklund

H. Ringertz M. Rosenstein Y. Yonekura

B. Yue 143

144

References 145

146 ICRP, 2000a. Avoidance of radiation injuries from medical interventional 147

procedures. ICRP Publication 85. Ann. ICRP 30 (2). 148


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ICRP, 2000b. Managing patient dose in computed tomography. ICRP Publication 149

87. Ann. ICRP 30 (4). 150

ICRP, 2007a. Managing patient dose in multi-detector computed tomography. ICRP 151

Publication 102. Ann. ICRP 37 (1). 152

ICRP, 2007b. Radiological protection in medicine. ICRP Publication 105. Ann. 153

ICRP 37 (6). 154

ICRP, 2009. Recommendations of the International Commission on Radiological 155

Protection. ICRP Publication 113, Ann. ICRP 39 (5). 156

ICRP, 2001. Radiation and your patient – a guide for medical practitioners. ICRP 157

Supporting Guidance 2. Ann. ICRP 31 (4). 158

159

160

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EXECUTIVE SUMMARY 162 163


percutaneous coronary interventions and electrophysiology procedures. Cardiac 165

nuclear medicine, cardiac CT, percutaneous coronary interventions and 166

electrophysiology procedures are increasing in number and account for an important 167

share of patient radiation exposure in medicine. Complex percutaneous coronary 168

interventions and cardiac electrophysiology procedures are associated with high 169

radiation doses. These procedures can result in patient skin doses high enough to 170

cause radiation injury and, in children, an increased risk of cancer. Treatment of 171

congenital heart disease in children is of particular concern. Additionally, staff in 172

cardiac catheterization laboratories may receive high radiation doses if radiological 173

protection tools are not used properly. 174

175

1. The Biological Effects of Radiation 176 177

Stochastic effects are malignant disease and heritable effects for which the 178

probability of an effect occurring, but not its severity, is regarded as a function of 179

dose without threshold. The likelihood of inducing a stochastic effect increases with 180

dose, but the exact relationship between dose and effect is not known. Children are 181

approximately 2-3 times more sensitive to the stochastic effects of radiation than 182

adults. They also have a longer potential lifespan than do adults, so they have more 183

time to develop possible radiation related sequelae. 184

Deterministic effects (e.g., skin injury) are due to injury in populations of 185

cells, characterised by a threshold dose and an increase in the incidence and severity 186

of the reaction as the dose is increased further. Deterministic effects are also termed 187

tissue reactions. Radiation-induced skin injuries may not become fully manifest until 188

months after the radiation dose was administered. The diagnosis of a radiation-189

induced skin injury is often delayed. Deterministic injuries may extend into deeper 190

tissues and can cause symptoms that persist for years. Deterministic injuries may be 191

accompanied by an increase in stochastic risk. 192

The mechanisms of heart radiation damage include inflammatory processes, in 193

particular after low doses, and after higher doses there is a progressive reduction in 194

the number of patent capillaries eventually leading to ischemia, myocardial cell 195

death and fibrosis, accelerated atherosclerosis in major blood vessels, decreased 196

cardiac function, and fatal congestive heart failure. Cardiovascular radiation effects 197

have been reported to occur at doses > 0.5 Gy. Organ doses may reach this level in 198

some complex fluoroscopically guided cardiac procedures. 199

The lens of the eye is a radiosensitive tissue. Ionizing radiation typically 200

causes posterior subcapsular cataract formation in the lens of the eye. Surveys of 201

cardiologists and support staff working in catheterization laboratories have found a 202

high percentage of lens opacities attributable to occupational radiation exposure 203

when radiological protection tools have not been used properly. 204

205

2. Principles of Radiological Protection for Patients and Staff 206 207

The Commission recommends three principles of radiological protection: 208

justification, optimization of protection, and application of dose limits (ICRP, 2007). 209

The first two are source related and apply to all radiation exposure situations. The 210


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third applies to staff, but does not apply to medical exposures of patients or to carers 211

and comforters. 212

Justification means that a medical procedure should only be performed when it 213

is appropriate for a particular patient— the anticipated clinical benefits should 214

exceed all anticipated procedural risks, including radiation risk. For CT and nuclear 215

medicine studies, justification is a responsibility shared between the referring 216

clinician and the cardiac imager. For fluoroscopically guided interventions, the 217

responsibility rests with the interventionalist. 218

Optimization means that the radiation dose to the patient is suitable for the 219

medical purpose, and radiation that is clinically unnecessary or unproductive is 220

avoided. Patient radiation dose is optimized when imaging is performed with the 221

least amount of radiation required to provide adequate image quality, diagnostic 222

information, and for fluoroscopy, adequate imaging guidance. 223

224

3. Managing patient dose in fluoroscopically guided interventions 225 226

The informed consent process should include information on radiation risk if 227

the risk of radiation injury is thought to be significant. Important aspects of the 228

patient‘s medical history that should be considered when estimating radiation risk 229

are genetic factors, co-existing diseases, medication use, radiation history, and 230

pregnancy. 231

Some of the factors that affect the patient‘s radiation dose depend on the x-ray 232

system, but many others depend on how the operator uses the x-ray system. During 233

the procedure, the cardiologist should be kept aware of the fluoroscopy time, the 234

number of cine series and cine frames, and the total patient dose. As patient 235

radiation dose increases, the operator should consider the radiation dose already 236

delivered to the patient and the additional radiation necessary to complete the 237

procedure. 238

Patient radiation dose reports should be produced at the end of the procedure, 239

and archived. Radiation dose data should be recorded in the patient‘s medical 240

record after the procedure. When the patient‘s radiation dose from the procedure is 241

high, clinical follow-up is essential for early detection and management of skin 242

injuries. Patients who have received a substantial radiation dose should have follow-243

up at 10-14 days and at one month after the procedure for potential radiation 244

injuries. 245

246

4. Protection of staff during interventional fluoroscopy 247

248

The basic tools of occupational radiological protection are time, distance and 249

shielding. The use of personal protective shielding is necessary in the cardiac 250

catheterization laboratory. Occupational doses can be reduced to very low levels if 251

ceiling suspended lead screens and protective lead curtains suspended from the side 252

of the procedure table are used properly. In general, reducing patient dose will also 253

reduce operator dose. With proper use of radiological protection tools and 254

techniques, the effective dose (E) for an interventionalist is typically 2–4 mSv/year, 255

and is well below the 20 mSv/year limit recommended by the Commission. 256

Radiation exposure to the operator is neither uniform nor symmetric. 257

Radiological protection for the eyes is necessary for interventionalists. Proper use of 258


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personal monitoring badges is necessary in cardiac catheterization laboratories in 259

order to monitor and audit occupational radiation dose. 260

261

5. Radiological protection for nuclear cardiology 262 263

Appropriate use criteria and guidelines that help to set standards for 264

justification of nuclear cardiology procedures have been developed through 265

consensus efforts of professional societies. Justification needs to be performed on 266

an individualized, patient-by-patient basis. Optimization of nuclear cardiology 267

procedures involves the judicious selection of radiopharmaceuticals and 268

administered activities to ensure diagnostic image quality while minimizing patient 269

dose. Administered activities should be within pre-specified ranges, as provided in 270

international and national guidelines, and should reflect patient habitus. If stress 271

imaging is normal, rest imaging can be omitted to minimize total dose. For SPECT 272

protocols, Tc-99m-based agents yield lower effective doses than Tl-201, and are 273

preferred on dosimetric grounds. Practitioners need good quality dosimetry data to 274

perform proper benefit-risk analyses for their patients. 275

276

6. Radiological protection for cardiac CT 277 278

Appropriate use criteria and guidelines for justification of cardiac CT have 279

been developed through consensus efforts of professional societies. Justification 280

needs to be performed on an individualized, patient-by-patient basis, weighing the 281

benefits and risks of each imaging test under consideration as well as of doing no 282

test. Assessment of radiation risk is one part of this process. 283

Dose from cardiac CT is strongly dependent on scanner mode, tube current, 284

and tube voltage. For patients with a heart rate less than 65-70 bpm and a regular 285

rhythm, diagnostic image quality can generally be maintained while using dose-286

reduction methods such as ECG-controlled tube current modulation and axial 287

imaging. The maximum tube current should be appropriate for the patient‘s habitus. 288

Further research is needed to develop and validate methods, such as newer scan 289

modes and low-voltage scanning, to minimize radiation dose to patients and 290

practitioners. 291

292

7. Radiological protection training for interventional fluoroscopy 293 294

Legislation in most countries requires that individuals who take responsibility 295

for medical exposures must be properly trained in radiological protection (RP). 296

Interventional cardiologists worldwide typically have little or no training in RP. The 297

Commission recommends that, in addition to the training recommended for other 298

physicians who use X-rays, interventionalists, including interventional cardiologists, 299

should receive a second, higher level of RP training. 300

Training programmes should include both initial training for all incoming staff 301

and regular updating and retraining. Scientific congresses should include refresher 302

courses on RP, attendance at which could be a requirement for continuing 303

professional development. 304

Training activities in RP should be followed by an evaluation of the 305

knowledge acquired from the training programme (a formal examination system). 306

Physicians who have completed training should be able to demonstrate that they 307


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possess the knowledge specified by the curriculum by passing an appropriate 308

certifying examination. 309

The Commission recommends that nurses and other healthcare professionals 310

who assist during fluoroscopic procedures should be familiar with radiation risks 311

and radiological protection principles, in order to minimise their own exposure and 312

that of others. 313

314

8. Quality assurance programmes 315 316

Two basic objectives of the radiological protection quality assurance 317

programme (QAP) are to evaluate patient radiation dose on a periodic basis and to 318

monitor occupational radiation dose for workers in cardiology facilities where 319

radiation is used. A cardiologist should be in charge of the QAP aspects of RP for 320

cardiology procedures, and should be assisted by a medical physicist. A senior 321

interventionalist and a medical physicist should be included in the planning for a 322

new interventional fluoroscopy laboratory, installation of a new x-ray or nuclear 323

medicine system and the upgrade of existing equipment. 324

Periodic evaluation of image quality and procedure protocols should be 325

included in the QAP. The QAP should establish a trigger level for individual clinical 326

follow-up when there is a risk of radiation-induced skin injuries. The QAP should 327

ensure the regular use of personal dosimeters and include a review of all abnormal 328

dose values. 329

Patient dose reports should be produced at the end of procedures, archived and 330

recorded in the patient‘s medical record. If dose reports are not available, dose 331

values should be recorded in the patient‘s medical record together with procedure 332

and patient identification. Patient dose audits (including comparison with Diagnostic 333

Reference Levels) and reporting are important components of the QAP. 334

335

9. Reference 336 337

ICRP, 2007. The 2007 Recommendations of the International Commission on 338

Radiological Protection. ICRP publication 103. Ann. ICRP 37, 1-332. 339 340


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Recommendations 341

342

Individuals who request, perform or interpret cardiology imaging 343

procedures should be aware of the radiation risks of the procedure. 344

Appropriate use criteria and guidelines for justification have been 345

developed and should be used in clinical practice. 346

Nuclear cardiology examinations and cardiac CT examinations should be 347

optimized and dose reduction techniques used whenever applicable. 348

The informed consent process should include information on radiation risk 349

if a risk of radiation injury is thought to exist. 350

Radiation dose data should be recorded in the patient’s medical record 351

after the procedure; patient dose reports should be archived for quality 352

assurance purposes. 353

When the patient’s radiation dose from an interventional procedure 354

exceeds the institution’s trigger level, clinical follow-up should be 355

performed for early detection and management of skin injuries. 356

Suggested values for the trigger level are a skin dose of 3 Gy, a kerma-area 357

product of 500 Gy·cm2, or an air kerma at the patient entrance reference 358

point of 5 Gy. 359

Individuals who perform cardiology procedures where there is a risk of 360

deterministic injury to patients should be able to recognize these skin 361

injuries. 362

Individuals who perform interventional cardiology procedures should be 363

familiar with methods to reduce radiation dose to patients and staff. 364

Nurses and other healthcare professionals who assist during fluoroscopic 365

procedures should be familiar with radiation risks and radiological 366

protection principles, in order to minimise their own exposure and that of 367

others. 368

Whenever there is a possibility of occupational radiation exposure, staff 369

should use personal protective shielding. 370

Training programmes in radiological protection should include both initial 371

training for all incoming staff and regular updating and retraining. 372

In addition to the training recommended for other physicians who use X-373

rays, interventionalists, including interventional cardiologists, should 374

receive a second, higher level of radiological protection training. 375

A cardiologist should be in charge of the quality assurance programme 376

aspects of radiological protection for cardiology procedures, and should be 377

assisted by a medical physicist. 378

Quality assurance programmes in cardiology should include patient dose 379

audits. 380

Quality assurance programmes should ensure the regular use of personal 381

dosimeters and should include a review of all abnormal dose values. 382 383

384


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385

386

GLOSSARY 387

388

1. Definitions 389 390

391

Absorbed dose, D 392

The fundamental dose quantity given by 393

394

395 396

Where d is the mean energy imparted to matter of mass dm by ionising 397

radiation. The SI unit for absorbed dose is joule per kilogram (J kg-1

). Its 398

special name is gray (Gy) (ICRP, 2007). In layman‘s terms, absorbed dose is 399

the measure of energy absorbed by tissue from ionizing radiation. 400

401

Acceptance test 402

A test carried out after new equipment has been installed or major 403

modifications have been made to existing equipment, in order to verify 404

compliance with the manufacturer‘s specifications, contractual specifications 405

and applicable local regulations. 406

407

ALARA 408

An acronym for As Low As Reasonably Achievable. See Optimisation of 409

protection. 410

411

Becquerel (Bq) 412

The special name for the SI unit of activity. 1 Bq = 1 s-1

(≈2.7 10-11

Ci). 413

414

Brachytherapy 415

Radiation treatment of a patient using sealed or unsealed sources of radiation 416

placed within the patient‘s body. 417

418

Bradycardia 419

An abnormally slow heart rhythm. Depending on the heart rate and the 420

underlying abnormality, bradycardias may or may not require treatment. 421

422

423

Cardiomyopathy 424

Any condition that results in weakening of the pumping strength of the 425

cardiac ventricles, or that causes areas of scar tissue to develop in the 426

ventricles. 427

428

Cardiovertor-defibrillator 429

Devices, usually implanted in the same way as pacemakers, that 430

continuously monitor the heart rhythm, automatically function as pacemakers 431


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for bradycardia, and deliver life-saving shocks if a dangerous tachycardia is 432

detected. 433

434

Carers and comforters 435

Individuals, other than staff, who care for and comfort patients. These 436

individuals include parents and others, normally family or close friends, who 437

hold children during diagnostic procedures or may come close to patients 438

following the administration of radiopharmaceuticals or during 439

brachytherapy (ICRP, 2007). 440

441

Commissioning 442

Testing carried out after new equipment has been installed, in order to verify 443

that the equipment is properly configured for its clinical application at the 444

centre (NCRP, 2010). 445

446

Constancy test 447

Each of a series of tests, carried out to ensure that the functional performance 448

of equipment meets established criteria, or to enable the early recognition of 449

changes in the properties of components of the equipment (IEC, 1993). 450

451

Deterministic effect 452

Injury in populations of cells, characterised by a threshold dose and an 453

increase in the severity of the reaction as the dose is increased further. 454

Deterministic effects are also termed tissue reactions. In some cases, 455

deterministic effects are modifiable by post-irradiation procedures including 456

biological response modifiers (ICRP, 2007). 457

458

Diagnostic reference level 459

Used in medical imaging with ionizing radiation to indicate whether, in 460

routine conditions, the patient dose or administered activity (amount of 461

radioactive material) from a specified procedure is unusually high or low for 462

that procedure (ICRP, 2007). 463

464

Diastasis 465

The midportion of diastole, when the blood enters the ventricle slowly or 466

ceases to enter. Diastasis duration is in inverse proportion to heart rate and is 467

absent at very high heart rates. 468

469

Dose coefficient 470

Used as a synonym for dose per unit intake of a radioactive substance, but 471

sometimes also used to describe other coefficients linking quantities or 472

concentrations of activity to doses or dose rates, such as the external dose 473

rate at a specified distance above a surface with a deposit of a specified 474

activity per unit area of a specified radionuclide (ICRP, 2007). 475

476

Dose limit 477

The value of the effective dose or the equivalent dose to individuals from 478

planned exposure situations that shall not be exceeded (ICRP, 2007). 479

480


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Dysrhythmia 481

A disorder of heart rhythm, also called arrhythmia. Dysrhythmias may be 482

due to electrical, circulatory or structural diseases or disorders. Some 483

dysrhythmias are harmless, and some are life-threatening. 484

485

Effective dose, E 486

The tissue-weighted sum of the equivalent doses in all specified tissues and 487

organs of the body, given by the expression: 488

489

490 491

where HT or wRDT,R is the equivalent dose in a tissue or organ, T, and wT is 492

the tissue weighting factor. The unit for the effective dose is the same as for 493

absorbed dose, J kg-1

. Its special name is sievert (Sv) (ICRP, 2007). 494

Effective dose was developed as a practical quantity for use in the general 495

system of radiation protection, particularly with regard to applying the 496

principles of optimization of radiation protection and dose limitation for 497

stochastic effects. 498

499

Electrophysiology 500

Cardiac electrophysiology is directed at evaluation and treating abnormalities 501

of the electrical conduction system of the heart. Cardiac electrophysiology 502

procedures involve the recording of intracardiac electrical signals and 503

programmed electrical stimulation of the heart. The procedure may be 504

performed for diagnostic purposes only or may be part of a combined 505

diagnostic and therapeutic (e.g., ablation) procedure. Catheters for pacing 506

and recording are advanced through blood vessels into multiple cardiac 507

chambers. The designs of the catheters and the sites appropriate for their 508

placement are determined according to the nature of the arrhythmia under 509

investigation. 510

511

Employer 512

An organisation, corporation, partnership, firm, association, trust, estate, 513

public or private institution, group, political or administrative entity, or other 514

persons designated in accordance with national legislation, with recognized 515

responsibility, commitment, and duties towards a worker in her or his 516

employment by virtue of a mutually agreed relationship. A self-employed 517

person is regarded as being both an employer and a worker (ICRP, 2007). 518

519

Equivalent dose, HT 520

The dose in a tissue or organ T given by: 521

522

523 524

where DT,R is the mean absorbed dose from radiation R in a tissue or organ 525

T, and wR is the radiation weighting factor. Since wR is dimensionless, the 526


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unit for the equivalent dose is the same as for absorbed dose, J kg-1

. This 527

unit‘s special name is sievert (Sv) (ICRP, 2007). For x-rays used in 528

fluoroscopy, wR = 1, so the equivalent dose is numerically equal to the mean 529

absorbed dose in mGy. 530

531

Fluoroscopically guided interventions 532

Procedures comprising guided therapeutic and diagnostic interventions, by 533

percutaneous or other access, usually performed under local anaesthesia 534

and/or sedation, with fluoroscopic imaging used to localise the 535

lesion/treatment site, monitor the procedure, and control and document the 536

therapy (ICRP, 2000). 537

538

Gray (Gy) 539

The special name for the SI unit of absorbed dose: 1 Gy = 1 J kg-1

. 540

541

Justification 542

The process of determining whether either (1) a planned activity involving 543

radiation is, overall, beneficial, i.e. whether the benefits to individuals and to 544

society from introducing or continuing the activity outweigh the harm 545

(including radiation detriment) resulting from the activity; or (2) a proposed 546

remedial action in an emergency or existing exposure situation is likely, 547

overall, to be beneficial, i.e., whether the benefits to individuals and to 548

society (including the reduction in radiation detriment) from introducing or 549

continuing the remedial action outweigh its cost and any harm or damage it 550

causes (ICRP, 2007). 551

552

Interventional Reference Point, see Patient Entrance Reference Point 553

554

KAP, see Kerma-area product 555

556

Kerma, K 557

The quotient of the sum of the kinetic energies, dEtr, of all charged particles 558

liberated by uncharged particles in a mass dm of material, and the mass dm 559

of that material. 560

561

562 563

Kerma is defined as a non-stochastic quantity and dEtr is the expectation 564

value of the sum of the kinetic energies. The unit for kerma is joule per 565

kilogram (J kg-1

). This unit‘s special name is gray (Gy) (ICRP, 2007). 566

―Kerma‖ is an acronym for Kinetic Energy Released in a Mass. 567

568

Kerma-area product, KAP 569

The integral of air kerma across the entire x-ray beam emitted from the x-ray 570

tube. Kerma-area product is a surrogate measurement for the entire amount 571

of energy delivered to the patient by the beam. Kerma-area product is 572

measured in units of Gy·cm2. This quantity was previously called dose-area 573


15

product. Earlier publications used the abbreviation ‗DAP‘ for this quantity 574

(Stecker et al, 2009). 575

576

Mean absorbed dose in a tissue or organ (T), DT 577

The absorbed dose DT, averaged over the tissue or organ T, which is given 578

by 579

580

581 582

where εT is the mean total energy imparted in a tissue or organ T, and mT is 583

the mass of that tissue or organ (ICRP, 2007). 584

585

Medical exposure 586

Exposure incurred by patients as part of their own medical or dental 587

diagnosis or treatment; by persons, other than those occupationally exposed, 588

knowingly, while voluntarily helping in the support and comfort of patients; 589

and by volunteers in a programme of biomedical research involving their 590

exposure (ICRP, 2007). 591

592

Myocardial perfusion 593

Blood flow to the heart muscle. 594

595

Occupational exposure 596

This refers to all exposure incurred by workers in the course of their work, 597

with the exception of 1) excluded exposures and exposures from exempt 598

activities involving radiation or exempt sources; 2) any medical exposure; 599

and 3) the normal local natural background radiation (ICRP, 2007). 600

601

Optimisation of protection (and safety) 602

The process of determining what level of protection and safety makes 603

exposures, and the probability and magnitude of potential exposures, as low 604

as reasonably achievable, economic and societal factors being taken into 605

account (ICRP, 2007). 606

607

Patient Entrance Reference Point 608

For isocentric fluoroscopic systems such as C-arm fluoroscopes, the Patient 609

Entrance Reference Point is located along the central x-ray beam at a 610

distance of 15 cm from the isocenter in the direction of the focal spot (IEC, 611

2010). The earlier version of this standard refers to this point as the 612

Interventional Reference Point. (IEC, 2000). The Patient Entrance Reference 613

Point is close to the patient‘s entrance skin surface when the heart is at the 614

isocenter of the gantry. 615

616


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Peak Skin Dose, PSD 617

The maximum absorbed dose to the most heavily irradiated localized region 618

of skin (i.e., the localized region of skin that lies within the primary x-ray 619

beam for the longest period of time during an FGI procedure). Peak skin 620

dose is measured in units of Gy (NCRP, 168). 621

622

Percutaneous coronary intervention (PCI) 623

PCI encompasses a variety of procedures used to treat patients with diseased 624

coronary arteries. A catheter is advanced into the diseased artery, and a 625

balloon is inflated within the stenotic portion of the artery, often 626

accompanied by placement of a stent (a wire mesh tube) to act as a 627

permanent scaffold. The procedure is commonly known as coronary 628

angioplasty. 629

630

Principles of protection 631

A set of principles that apply equally to all controllable exposure situations: 632

the principle of justification, the principle of optimisation of protection, and 633

the principle of application of limits on maximum doses in planned situations 634

(ICRP, 2007). 635

636

PSD, see Peak Skin Dose 637

638

Radiation weighting factor, wR 639

A dimensionless factor by which the organ or tissue absorbed dose is 640

multiplied to reflect the higher biological effectiveness of high-LET 641

radiations compared with low-LET radiations. It is used to derive the 642

equivalent dose from the absorbed dose averaged over a tissue or organ 643

(ICRP, 2007). 644

645

Radiofrequency ablation 646

In cardiology, a procedure where one or more catheters are guided via 647

fluoroscopy into the blood vessels and directed to the heart muscle. A burst 648

of radiofrequency energy destroys very small areas of tissue that give rise to 649

abnormal electrical signals. 650

651

Reference Air Kerma (RAK) 652

Air kerma of the primary X-ray beam measured under specific conditions 653

and expressed as the equivalent value at the Patient Entrance Reference Point 654

(IEC, 2004, IEC, 2010). It is the air kerma accumulated at a specific point in 655

space relative to the fluoroscopic gantry (see Patient Entrance Reference 656

Point, above) during a procedure. Reference air kerma does not include 657

backscatter and is measured in units of Gy. Reference air kerma is sometimes 658

referred to as reference dose or cumulative air kerma. Earlier publications 659

used the term ‗cumulative dose‘ and the abbreviation ‗CD‘ for this quantity 660

(Stecker, 2009). 661

662

Sievert (Sv) 663

The special name for the SI unit of equivalent dose, effective dose, and 664

operational dose quantities. The unit is joule per kilogram (J kg-1

). 665


17

666

SRDL, see Substantial Radiation Dose Level 667

668

Stochastic effects of radiation 669

Malignant disease and heritable effects for which the probability of an effect 670

occurring, but not its severity, is regarded as a function of dose without 671

threshold (ICRP, 2007). 672

673

Stenosis 674

Narrowing of a hollow structure. With respect to percutaneous coronary 675

interventions, narrowing of the inner diameter of a coronary artery. 676

677

Stress test 678

A standardized procedure for assessing the effect of stress on heart function 679

and myocardial perfusion. Stress may be induced by exercise or simulated by 680

administration of drugs. A normal stress test implies that blood flow through 681

the coronary arteries is normal. 682

683

Substantial Radiation Dose Level (SRDL) 684

An appropriately selected reference value used to trigger additional dose 685

management actions during a procedure and medical follow-up for a 686

radiation level that might produce a clinically relevant injury in an average 687

patient. There is no implication that radiation levels above the SRDL will 688

always cause an injury or that radiation levels below the SRDL will never 689

cause an injury (NCRP 168, 2010). 690

691

Tachycardia 692

An abnormally fast heart rhythm. Depending on the heart rate and the 693

underlying abnormality, tachycardias may or may not require treatment. 694

695

Threshold dose for tissue reactions 696

Dose estimated to result in only 1% incidence of tissue reactions (ICRP, 697

2007). 698

699

Tissue reaction 700

See ‗Deterministic effect‘. 701

702

Tissue weighting factor, wT 703

The factor by which the equivalent dose in a tissue or organ T is weighted to 704

represent the relative contribution of that tissue or organ to the total health 705

detriment resulting from uniform irradiation of the body (ICRP 1991). It is 706

weighted such that: 707

708

709 710

(ICRP, 2007). 711

712

Valvular heart disease 713


18

Heart disease due to one or more abnormal heart valves. Abnormally 714

narrowed or leaky heart valves can interfere with the heart‘s ability to push 715

blood forward from chamber to chamber, and then out to the lungs and body. 716

717

Worker 718

Any person who is employed, whether full time, part time or temporarily, by 719

an employer, and who has recognised rights and duties in relation to 720

occupational radiological protection (ICRP, 2007). 721

722

2. References 723

724 IEC, 1993. Medical electrical equipment - Part 1-61223: Evaluation and routine 725

testing in medical imaging departments. 1st ed. Geneva, Switzerland: 726

International Electrotechnical Commission. 727

IEC, 2000. Medical electrical equipment. Part 2-43: Particular requirements for the 728

safety of X-ray equipment for interventional procedures. IEC 60601-2-43. 729

Geneva, Switzerland: International Electrotechnical Commission. 730

IEC, 2004. Medical electrical equipment - Technical Report 60788: Glossary of 731

defined terms. IEC TR 60788. 2nd

edition. Geneva, Switzerland: International 732

Electrotechnical Commission. 733

IEC, 2010. Medical electrical equipment. Part 2-43: Particular requirements for the 734

safety of X-ray equipment for interventional procedures. IEC 60601-2-43. 2nd

735

edition. Geneva, Switzerland: International Electrotechnical Commission. 736


Radiological Protection. ICRP Publication 60. Ann ICRP 21(1-3):1-201. 738

ICRP, 2000. Avoidance of radiation injuries from medical interventional 739

procedures. ICRP Publication 85. Ann ICRP 30:7-67. 740


Radiological Protection. ICRP Publication 103. Ann ICRP 37(2-4):1-332. 742

NCRP, 2010. Radiation dose management for fluoroscopically guided 743

interventional medical procedures. NCRP Report No. 168. Bethesda, MD: 744

National Council on Radiation Protection and Measurements. 745

Stecker MS, Balter S, Towbin RB, Miller DL, Vañó E, Bartal G, Angle JF, Chao 746

CP, Cohen AM, Dixon RG, Gross K, Hartnell GG, Schueler B, Statler JD, de 747

Baère T, and Cardella JF. Guidelines for patient radiation dose management. J 748

Vasc Interv Radiol 2009; 20: S263-S273. 749

750


19

751

752

753

1. INTRODUCTION 754

755

Main Points 756

757


percutaneous coronary interventions, electrophysiology procedures, 759

procedures for the correction of congenital heart disease or acquired 760

valvular disease, and other vascular interventional procedures. 761

Cardiac nuclear medicine, CT, percutaneous coronary interventions and 762

electrophysiology procedures are increasing in number and account for a 763

disproportionate share of patient radiation exposure. 764

Interventional cardiology procedures can result in patient skin doses high 765

enough to cause radiation injury and an increased risk of cancer in 766

children. 767

Complex percutaneous coronary interventions and cardiac 768

electrophysiology procedures are associated with higher radiation doses 769

Treatment of congenital heart disease in children is of particular concern, 770

due to their greater sensitivity to radiation. 771

Staff in cardiac catheterization laboratories may receive high radiation 772

doses if radiological protection tools are not used properly. 773 774

1.0 Introduction 775 776

(1) In cardiology, patients are exposed to ionizing radiation from three 777

different modalities: fluoroscopy (including cineangiography), computed 778

tomography (CT) and nuclear medicine. These three modalities differ considerably 779

in the frequency with which they are performed, in patient radiation doses, in the 780

way radiation is administered to the patient, and in radiation dose to operators and 781

staff. 782

783

1.1 Fluoroscopically guided procedures 784

785 (2) Cardiologists perform a variety of fluoroscopically guided procedures. 786

These include procedures to diagnose and treat abnormal coronary arteries, 787

procedures to diagnose and treat cardiac dysrhythmias, procedures to diagnose and 788

treat congenital and valvular heart disease and other vascular interventions. These 789

procedures may be performed on patients of all ages, from newborns to the elderly. 790

The Commission has addressed avoidance of radiation injury from fluoroscopically 791

guided procedures in the past (ICRP 2000), but advances in technology and in our 792

understanding of radiation effects have occurred in the past decade. 793

794

1.1.1 Percutaneous coronary interventions (PCI) 795

796 (3) Despite the continuing development of non-invasive cardiac imaging 797

techniques over the past decade, including echocardiography, cardiac CT scanning 798

and cardiac MRI, an increasing number of patients undergo fluoroscopically guided 799


20

invasive cardiac diagnostic and therapeutic procedures. In Europe there was a 3-fold 800

increase in coronary angiography (CA) and a 5-fold increase in percutaneous 801

coronary interventions (PCI) between 1992 and 2001, primarily due to the 802

introduction of coronary stents (Togni, et al, 2004, fig. 1.1) Between 1990 and 2003, 803

the average annual rate of increase in coronary angioplasty procedures in Europe 804

ranged from 3.78% in the Netherlands to 11.82% in Finland, with a mean of 6.73% 805

(Faulkner and Werduch, 2008a). An estimated 3,043,000 coronary arteriograms and 806

910,000 percutaneous coronary interventions, with 690,000 coronary stent 807

placements, were performed in Europe in 2007 (Faulkner and Werduch, 2008b). 808

(4) Similar growth rates were observed in North America (Laskey et al, 2000, 809

Anderson et al, 2002) for the time period 1990-2000. Between 2006 and 2008, 810

however, the number of invasive coronary procedures in the U.S. declined by 811

approximately 2% (NCRP Report 168, 2010), and appears to be declining in some 812

European countries as well (Meier, 2010). This is presumed due to the increase in 813

cardiac CT. 814

(5) In the United States, interventional fluoroscopy procedures were the third 815

largest source of medical exposure of patients in 2006, accounting for 14% of 816

medical exposure (NCRP report 160, 2009). Cardiac procedures were 28% of the 817

total interventional fluoroscopy procedures, but accounted for 53% of the 818

interventional fluoroscopy exposure. 819

820

821

822

Figure 1.1: Coronary angiograms, coronary angioplasty (PTCA) and 823

coronary stenting in Europe from 1992—2001, in thousands of procedures 824

(from Togni, EHJ reproduced with permission [to be requested from Elsevier 825

Ltd.]) 826

827


21

(6) This growth has involved mainly the Western world, but a similar trend is 828

seen in other countries: in China the annual increment rate for PCI is around 40% 829

(Cheng et al, 2004). This number is relatively small and may reflect the lower 830

prevalence of coronary artery disease in the Chinese population (3-7%, about one 831

quarter of that of Western Caucasians), but is expected to grow as a consequence of 832

changing dietary habits, life-style and cigarette smoking (Cheng et al, 2004, Moran 833

2010). 834

(7) A survey of developing countries conducted by the IAEA revealed that 835

about 30% of the 20 participating countries demonstrated a 100% increase in 836

workload in the 3-year period from 2004 to 2007 (Tsapaki, 2009). The same study 837

indicated that the numbers of paediatric interventional procedures can reach the 838

levels of adult interventional procedures, even in developing countries. 839

840

1.1.2 Skin injuries 841

(8) Both PCI and interventional electrophysiology procedures can result in 842

patient skin doses high enough to cause deterministic skin injuries (see Chapters 2 843

and 3) (Miller 2008). At one centre, the frequency of skin injuries was estimated at 844

3 x 10-4

(Padovani 2005). Although the number of radiation injuries due to cardiac 845

procedures remains small, these injuries have a major impact on the patients who are 846

affected. Therefore, it is important to inform and continue to remind practicing 847

clinicians of the potential risks involved with these procedures. 848

(9) The number of patients undergoing multiple procedures continues to 849

increase (Laskey et al, 2001). Complex cases may be treated in more than one 850

session (staged procedures). Restenosis and disease progression may also prompt 851

repeated interventions. In a recent series of 3332 patients (Padovani et al, 2005) 852

almost one third underwent at least two procedures. Vano et al. (Vano 2001) 853

observed a much greater rate of skin effects in patients who had undergone multiple 854

fluoroscopically guided coronary procedures. Repeated procedures, especially when 855

performed within a short period of time, increase the risk of skin injury (Balter, 856

2010). Multiple cardiac fluoroscopic procedures should be a cause of concern with 857

regard to radiological protection. The risk of skin injuries should not be 858

underestimated. 859

(10) Patient radiation dose is related to procedure complexity (Bernardi et al, 860

2000, Peterzol et al, 2002, Balter et al, 2009, IAEA 2009). Multi-vessel PCI is 861

considered a complexity factor, but this may not be always the case (Bernardi et al, 862

2000). Other factors that appear to affect complexity for PCI include the type of 863

lesion, the chronicity of the occlusion, the degree of vessel tortuosity and the 864

involvement of vessel bifurcations (Balter et al, 2009, IAEA 2009). 865

866

1.1.3 Cardiac electrophysiology procedures 867

(11) A second field where there has been an increase in both the number and 868

complexity of procedures is interventional electrophysiology. Permanent pacemaker 869

implantation for bradycardia is carried out in large numbers of patients. From 1997 870

to 2001, the number of new pacemaker implants increased about 50% worldwide 871

(Mond et al, 2004). More recently, bi-ventricular pacemakers (cardiac 872

resynchronisation therapy) have been introduced for the treatment of patients with 873

cardiac failure and cardiomyopathies (Salukhe et al, 2004). The use of cardioverter-874

defibrillators has also increased, as a result of studies (Moss et al, 2002, Salukhe et 875


22

al, 2004) that demonstrated their life-saving role in patients at risk of sudden cardiac 876

death. An estimated 554,000 pacemaker implantations were performed in Europe in 877

2007 (Faulkner and Werduch, 2008b) and an estimated 189,000 electrophysiology 878

procedures and 361,000 cardiac device implantations were performed in the U.S. in 879

2008 (NCRP Report No. 168, 2010). 880

(12) Cardiac electrophysiology procedures also include treatment of patients 881

with re-entrant tachycardias. These patients are often much younger than patients 882

with coronary heart disease, and require both diagnostic procedures and treatment by 883

radiofrequency ablation. Due to the long fluoroscopy times required for these 884

procedures, these patients can be exposed to very high radiation doses and a 885

substantial risk of deterministic effects if technique is not optimized (Rosenthal, 886

1998, McFadden, 2002). 887

888

1.1.4 Congenital and valvular heart disease 889

(13) Two other groups of cardiac disease where catheter techniques are used 890

and are likely to expand in the near future are congenital and valvular heart disease. 891

These groups represent a small percentage of patients undergoing percutaneous 892

interventions, but these diseases are seen in both children and adults. Children are at 893

greater risk for the development of stochastic radiation effects, principally cancer, 894

due to their longer expected life span and their increased sensitivity to radiation as 895

compared to adults (Hall, 2009). It has been estimated that approximately 7% of all 896

cardiac angiography procedures are carried out in children aged 0 to 15 years 897

(UNSCEAR 2000). The most widely performed procedures are balloon 898

valvuloplasty, device closure of atrial septal defect, patent foramen ovale or ductus 899

arteriosus, stenting of pulmonary artery stenosis or coarctation of the aorta and 900

electrophysiology studies. These procedures may involve long fluoroscopy times. In 901

addition to these well-established procedures, new procedures have been introduced, 902

including percutaneous pulmonary and aortic valve replacement, ventricular septal 903

defect closure, implantation of banding devices to limit pulmonary blood flow, and 904

radiofrequency perforation to create continuity between cardiac chambers and 905

vessels (Levi et al, 2003). (Percutaneous aortic valve replacement is performed 906

primarily in elderly patients unfit for surgery). A percutaneous or combined 907

percutaneous/surgical approach has been proposed to treat complex diseases such as 908

hypoplastic left heart syndrome. Fetal interventions are also possible. 909

(14) These techniques to treat congenital and valvular heart disease are largely 910

justified as they may replace very high-risk surgical procedures. Although 911

transesophageal and intracardiac ultrasound may partially replace fluoroscopy (Rice 912

et al, 2002, Zanchetta et al, 2004), radiation risk still remains a problem and is often 913

underestimated. Fluoroscopy times as high as 129 minutes may be required to 914

implant a pulmonary valve (Bonhoeffer et al, 2002). There is little literature 915

concerning the safety issues of these new devices to be used in infants and children 916

(Levi et al, 2003). 917

918

1.1.5 Paediatric patients 919

(15) A survey of patient doses in 137 children, aged from < 1 year to 16 years, 920

undergoing cardiac procedures performed using a biplane flat panel detector X-ray 921

system, demonstrated mean values of 1.9 to 8.6 Gy·cm2 for diagnostic procedures. 922

Mean dose values for therapeutic procedures, in both extremes of the paediatric age 923


23

group, ranged from 2.4 to 17.8 Gy·cm2 (Martinez et al, 2007). In a series of 205 924

children (mean age 4.1 y) who underwent diagnostic cardiac catheterization, the 925

mean dose was 17 Gy·cm2 (Chida et al, 2010). In comparison to proposed diagnostic 926

reference levels for fluoroscopically guided cardiac interventions in adults of 50 927

Gy·cm2 for diagnostic procedures and 125 Gy·cm

2 for therapeutic procedures 928

(Balter et al, 2008), paediatric patients have typically received less than 20% of the 929

dose received by adult patients. Nonetheless, radiation doses from paediatric cardiac 930

catheterization procedures are of concern (Andreassi, 2006, Andreassi, 2009). 931

932

1.2 Cardiac CT 933 934

(16) Cardiac CT technology has evolved rapidly in recent years, and these 935

advancements have enabled a variety of types of cardiac CT studies to be performed 936

that go well beyond detection of the coronary arteries. Today, cardiac CT 937

encompasses several distinct procedures, including coronary artery calcium (CAC) 938

scoring, CT coronary angiography (CTCA), pulmonary vein CT angiography, and 939

CT attenuation correction of nuclear cardiology image data. Recent technological 940

advances have been associated with an increase in the number of procedures 941

performed, although reliable statistics on worldwide numbers are not presently 942

available. In the United States, CT was the largest source of medical exposures to 943

patients in 2006, accounting for 49% of the medical exposure of patients (NCRP 944

report 160, 2009). Cardiac CT (including CTCA and CAC) accounted for 4.7% of 945

CT examinations, but 12.1% of patient exposure from CT. 946

947

1.3 Nuclear cardiology 948

949 (17) An estimated 32.7 million diagnostic nuclear medicine procedures are 950

performed annually worldwide (UNSCEAR 2008). Of these, approximately 14 951

million are nuclear cardiology procedures, and this number has increased rapidly 952

(Davis, 2006). More than 90% of nuclear cardiology studies are myocardial 953

perfusion scintigraphy studies for the assessment of myocardial perfusion and/or 954

viability. The vast majority of nuclear cardiology procedures performed employ 955

single photon emission computed tomography (SPECT), although a small but 956

growing number of laboratories perform positron emission tomography (PET) 957

studies. 958

(18) In the U.S., nuclear medicine procedures accounted for 26% of the 959

medical exposure of patients in 2006, and cardiac studies accounted for 85% of the 960

nuclear medicine exposure (NCRP report 160, 2009). Nuclear medicine procedures 961

were the second largest source of medical exposures, after CT. 962

(19) More nuclear cardiology procedures are performed in the United States 963

than in the rest of the world combined. Reasons suggested for this disparity include 964

better access to testing, a more litigious medicolegal climate, and profit motives for 965

testing. However, multiple U.S. series have demonstrated that for those procedures 966

where sufficient data are available to permit a determination of appropriateness, only 967

~15% are performed for inappropriate indications (Gibbons, 2008; Hendel, 2010). 968

Nonetheless, cardiologists should consider using alternative methodologies that do 969

not require ionizing radiation, such as stress echocardiography, whenever possible. 970

971

972


24

1.4 Occupational radiation risk 973

(20) Radiation risk is not limited to patients. Operators and staff receive 974

radiation exposure during fluoroscopically guided procedures. The increased 975

complexity of interventional cardiology procedures appears to have offset dose 976

reductions due to improvements in technology (Kim, 2008). There is considerable 977

variation in operator doses observed for the same type of procedure, indicating that 978

radiological protection practices can be improved (Kim, 2009). Recent studies have 979

shown that there is an increased incidence of radiation-related cataracts in 980

interventional cardiologists when radiological protection tools are not used properly 981

(Vano, 2010, Ciraj-Bjelac, 2010) Unfortunately, there is lack of proper monitoring 982

of radiation doses to staff and lack of reliable data on occupational doses (Padovani, 983

2011). 984

985

1.5 Summary 986

(21) In summary, fluoroscopically guided cardiology procedures are increasing 987

in number and complexity. The benefits for patients are clear, but radiation doses for 988

both patients and staff are important and must be managed appropriately. For young 989

patients, the increased risk of cancer should be considered in the optimisation of 990

these procedures. For older patients cancer risk is not as important, but avoidance of 991

deterministic effects (skin injuries) should be taken into account. Interventional 992

cardiologists are among the radiation workers with the highest occupational 993

radiation risk, and should know how to protect both patients and themselves. This 994

ICRP report is intended to help achieve this goal. 995

996

1.6 References 997

Anderson HV, Shaw RE, Brindis RG, Hewitt K, Krone RJ, Block PC, McKay CR, 998

Weintraub WS. A contemporary overview of percutaneous coronary 999

interventions. The American College of Cardiology-National Cardiovascular 1000

Data Registry (ACC-NCDR). J Am Coll Cardiol 2002; 39:1096-103. 1001

Andreassi MG, Ait-Ali L, Botto N, Manfredi S, Mottola G, Picano E. Cardiac 1002

catheterization and long-term chromosomal damage in children with congenital 1003

heart disease. Eur Heart J 2006; 27:2703–2708. 1004

Andreassi MG. Radiation risk from pediatric cardiac catheterization: friendly fire 1005

on children with congenital heart disease. Circulation 2009;120(19):1847-1849. 1006

Balter S, Miller DL, Vano E, Ortiz Lopez P, Bernardi G, Cotelo E, Faulkner K, 1007

Nowotny R, Padovani R, Ramirez A. A pilot study exploring the possibility of 1008

establishing guidance levels in x-ray directed interventional procedures. Med 1009

Phys 2008;35:673-80. 1010

Balter S, Hopewell JW, Miller DL, Wagner LK, Zelefsky MJ. Fluoroscopically 1011

guided interventional procedures: A review of radiation effects on patients' skin 1012

and hair. Radiology 2010;254:326-341. 1013

Bernardi G, Padovani R, Morocutti G, Vano E, Malisan MR, Rinuncini M, 1014

Spedicato L, Fioretti PM. Clinical and technical determinants of the complexity 1015

of PTCA procedures. Analysis in relation to radiation exposure parameters. 1016

Cathet Cardiovasc Interv 2000;51:1-9. 1017

Bonhoeffer P, Boudjemline Y, Qureshi SA, Le Bidois J, Iserin L, Acar P, Merckx J, 1018

Kachaner J, Sidi D. Percutaneous insertion of the pulmonary valve. J Am Coll 1019

Cardiol 2002;39:1664-9. 1020


25

1021

Ciraj-Bjelac O, Rehani MM, Sim KH, Liew HB, Vano E, Kleiman NJ. Risk for 1022

radiation induced cataract for staff in interventional cardiology: Is there reason 1023

for concern? Catheter Cardiovasc Interv 2010;76(6):826-834. 1024

Cheng TO. The current state of cardiology in China. Int J Cardiol. 2004 1025

Sep;96(3):425-39. 1026

Chida K, Ohno T, Kakizaki S, Takegawa M, Yuuki H, Nakada M, Takahashi S, 1027

Zuguchi M. Radiation dose to the pediatric cardiac catheterization and 1028

intervention patient. AJR American Journal of Roentgenology 2010; 1029

195(5):1175-1179. 1030

Davis W. Mapping improvements in molecular imaging. Medical Imaging. 1031

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Accessed December 31, 2010. 1034

Fajadet J, Morice MC, Bode C, Barragan P, Serruys PW, Wijns W, Constantini CR, 1035

Guermonprez JL, Eltchaninoff H, Blanchard D, Bartorelli A, Laarman GJ, Perin 1036

M, Sousa JE, Schuler G, Molnar F, Guagliumi G, Colombo A, Ban Hayashi E, 1037

Wulfert E. Maintenance of long-term clinical benefit with sirolimus-eluting 1038

coronary stents: three-year results of the RAVEL trial. Circulation 1039

2005;111:1040-4. 1040

Faulkner K, Werduch A. An estimate of the collective dose to the European 1041

population from cardiac x-ray procedures. Br J Radiol 2008a; 81:955-962. 1042

Faulkner K, Werduch A. Analysis of the frequency of interventional cardiology in 1043

various European countries. Rad Prot Dosim 2008b; 129(1-3):74-76. 1044

Hall EJ. Radiation biology for pediatric radiologists. Pediatr Radiol 2009;39 Suppl 1045

1:S57-64. 1046

Gibbons RJ, Miller TD, Hodge D, et al. Application of appropriateness criteria to 1047

stress single-photon emission computed tomography sestamibi studies and 1048

stress echocardiograms in an academic medical center. J Am Coll Cardiol. 1049

2008;51(13):1283-1289.International Atomic Energy Agency. Establishing 1050

guidance levels in x ray guided medical interventional procedures: A pilot 1051

study. Safety Reports Series No. 59. Vienna: International Atomic Energy 1052

Agency; 2009. 1053

Hendel RC, Cerqueira M, Douglas PS, et al. A multicenter assessment of the use of 1054

single-photon emission computed tomography myocardial perfusion imaging 1055

with appropriateness criteria. J Am Coll Cardiol. 2010;55(2):156-162. 1056

International Commission on Radiological Protection. Avoidance of radiation 1057

injuries from medical interventional procedures. ICRP Publication 85. Ann 1058

ICRP 2000;30:7-67. 1059

Kim KP, Miller DL, Balter S, Kleinerman RA, Linet MS, Kwon D, Simon SL. 1060

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procedures. Health Phys 2008;94:211-227. 1062

Kim KP, Miller DL. Minimising radiation exposure to physicians performing 1063

fluoroscopically guided cardiac catheterisation procedures: a review. Radiat 1064

Prot Dosimetry 2009;133:227-33. 1065

Laskey WK, Kimmel S, MD, Krone RJ. Contemporary Trends in Coronary 1066

Intervention: A Report From the Registry of the Society for Cardiac 1067

Angiography and Interventions Cathet. Cardiovasc. Intervent. 49:19–22, 2000. 1068

http://www.imagingeconomics.com/issues/articles/MI_2006-05_01.asp


26

Laskey WK, Williams DO, Vlachos HA, MS, H, Holmes DR, King SB, Kelsey SF, 1069

Slater J, Faxon D, Al-Bassam M, Block E, Detre KM for the Dynamic Registry 1070

Investigators. Changes in the Practice of Percutaneous Coronary Intervention: A 1071

Comparison of Enrollment Waves in the National Heart, Lung, and Blood 1072

Institute (NHLBI) Dynamic Registry. Am J Cardiol 2001;87:964–969. 1073

Lemos PA, Serruys PW, van Domburg RT, Saia F, Arampatzis CA, Hoye A, 1074

Degertekin M, Tanabe K, Daemen J, Liu TK, McFadden E, Sianos G, Hofma 1075

SH, Smits PC, van der Giessen WJ, de Feyter PJ. Unrestricted utilization of 1076

sirolimus-eluting stents compared with conventional bare stent implantation in 1077

the "real world": the Rapamycin-Eluting Stent Evaluated At Rotterdam 1078

Cardiology Hospital (RESEARCH) registry. Circulation 2004;109:190-5. 1079

Levi DS, Alejos JC, Moore JW. Future of interventional cardiology in pediatrics. 1080

Curr Opin Cardiol. 2003;18:79-90. 1081

Martinez LC, Vano E, Gutierrez F, Rodriguez C, Gilarranz R, Manzanas MJ. 1082

Patient doses from fluoroscopically guided cardiac procedures in pediatrics. 1083

Phys Med Biol. 2007;52(16):4749-59. 1084

McFadden SL, Mooney RB, Shepherd PH. X-ray dose and associated risks from 1085

radiofrequency catheter ablation procedures. Br J Radiol 2002;75:253-65. 1086

Meier, B. Cardiac catheterization interventions: European statistics 2007/2008. 1087

Presented at Euro PCR, May, 2010. Available at: 1088

http://www.escardio.org/communities/EAPCI/Documents/Cardiac-1089

catheterization-Interventions-stats07-08-EAPCI-Assembly-may2010.pdf 1090

Accessed February 22, 2011. 1091

Miller DL. Overview of contemporary interventional fluoroscopy procedures. 1092

Health Phys 2008;95:638-44. 1093

Mond HG, Irwin M, Morillo C, Ector H. The world survey of cardiac pacing and 1094

cardioverter defibrillators: calendar year 2001. Pacing Clin Electrophysiol 1095

2004;27:955-64 1096

Moran A, Gu D, Zhao D, Coxson P, Wang YC, Chen CS, Liu J, Cheng J, Bibbins-1097

Domingo K, Shen YM, He J, Goldman L. Future cardiovascular disease in 1098

china: markov model and risk factor scenario projections from the coronary 1099

heart disease policy model-china. Circ Cardiovasc Qual Outcomes. 1100

2010;3(3):243-52. 1101

Morice MC, Serruys PW, Sousa JE, Fajadet J, Ban Hayashi E, Perin M, Colombo 1102

A, Schuler G, Barragan P, Guagliumi G, Molnar F, Falotico R; RAVEL Study 1103

Group. Randomized Study with the Sirolimus-Coated Bx Velocity Balloon-1104

Expandable Stent in the Treatment of Patients with de Novo Native Coronary 1105

Artery Lesions. A randomized comparison of a sirolimus-eluting stent with a 1106

standard stent for coronary revascularization. N Engl J Med 2002;346:1773-80. 1107

Moss AJ, Zareba W, Hall WJ, Klein H, Wilber DJ, Cannom DS, Daubert JP, 1108

Higgins SL, Brown MW, Andrews ML; Multicenter Automatic Defibrillator 1109

Implantation Trial II Investigators. Prophylactic implantation of a defibrillator 1110

in patients with myocardial infarction and reduced ejection fraction. N Engl J 1111

Med 2002;346:877-83. 1112

National Council on Radiation Protection and Measurements. Ionizing radiation 1113

exposure of the population of the United States. NCRP Report No. 160. 1114

Bethesda, MD: National Council on Radiation Protection and Measurements; 1115

2009. 1116

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27

National Council on Radiation Protection and Measurements. Radiation dose 1117

management for fluoroscopically guided interventional medical procedures. 1118

NCRP Report No. 168. Bethesda, MD: National Council on Radiation 1119

Protection and Measurements; 2010. 1120

Padovani R, Bernardi G, Quai E, Toh HS, Signor M, Morocutti G, Spedicato L. 1121

Retrospective evaluation of occurrence of skin injuries in interventional cardiac 1122

procedures. Radiat Prot Dosimetry 2005; 117 (1-3):247-250. 1123

Padovani, R., Le Heron, J., Cruz-Suarez, R., Duran, A., Lefaure, C., Miller, D.L., 1124

Sim, H.K., Vano, E., Rehani, M., Czarwinski, R., 2010. International project on 1125

individual monitoring and radiation exposure levels in interventional 1126

cardiology. Radiat Prot Dosimetry 2011; in press. 1127

Peterzol A, Quai E, Padovani R, Bernardi G, Kotre J, Dowling A. Reference levels 1128

in PTCA as a function of procedure complexity. Radiat Prot Dosimetry 1129

2005;117 (1-3): 54-58. 1130

Prieto C, Vano E, Fernández JM, Galvan C, Sabate M, Gonzalez L, Martinez D. Six 1131

years experience in intracoronary brachytherapy procedures: patient doses from 1132

fluoroscopy. Br J Radiol. 2006 Sep; 79(945): 730-733. 1133

Rice MJ, McDonald RW, Li X, Shen I, Ungerleider RM, Sahn DJ. New 1134

Technology and Methodologies for Intraoperative, Perioperative, and 1135

Intraprocedural Monitoring of Surgical and Catheter Interventions for 1136

Congenital Heart Disease Echocardiography 2002; 19:725-734. 1137

Rosenthal LS, Mahesh M, Beck TJ, Saul JP, Miller JM, Kay N, Klein LS, Huang S, 1138

Gillette P, Prystowsky E, Carlson M, Berger RD, Lawrence JH, Yong P, 1139

Calkins H. Predictors of fluoroscopy time and estimated radiation exposure 1140

during radiofrequency catheter ablation procedures. Am J Cardiol 1998;82:451-1141

458. 1142

Salukhe TV, Dimopoulos K, Francis D. Cardiac resynchronisation may reduce all-1143

cause mortality: meta-analysis of preliminary COMPANION data with 1144

CONTAK-CD, InSync ICD, MIRACLE and MUSTIC. Int J Cardiol 1145

2004;93:101-3. 1146

The SoS Investigators. Coronary artery bypass surgery versus percutaneous 1147

coronary intervention with stent implantation in patients with multivessel 1148

coronary artery disease (the Stent or Surgery trial): a randomized controlled 1149

trial. Lancet 2002;360:965–70. 1150

Togni M, Balmer F, Pfiffner D, Maier W, Zeiher AM, Meier B, on behalf of the 1151

Working Group Interventional Cardiology and Coronary Pathophysiology of the 1152

European Society of Cardiology. Percutaneous coronary interventions in Europe 1153

1992–2001. Eur Heart J 2004;25:1208–1213. 1154

Tsapaki, V., Ahmed, N.A., AlSuwaidi, J.S., Beganovic, A., Benider, A., 1155

BenOmrane, L., Borisova, R., Economides, S., El-Nachef, L., Faj, D., 1156

Hovhannesyan, A., Kharita, M.H., Khelassi-Toutaoui, N., Manatrakul, N., 1157

Mirsaidov, I., Shaaban, M., Ursulean, I., Wambani, J.S., Zaman, A., Ziliukas, J., 1158

Zontar, D., Rehani, M.M., 2009. Radiation exposure to patients during 1159

interventional procedures in 20 countries: initial IAEA project results. AJR. 1160

Am. J. Roentgenol. 193, 559-569. 1161

UNSCEAR. Sources and effects of ionizing radiation: volume I, sources: annex D, 1162

medical radiation exposure. Report to the General Assembly of the United 1163

Nations; 2000; New York, NY Available at: 1164


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http://www.unscear.org/unscear/en/publications/2000_1.html Accessed 1165

December 31, 2010. 1166

UNSCEAR. Sources of ionizing radiation: volume I. Report to the General 1167

Assembly, with scientific annexes; 2010; New York, NY. Available at: 1168

http://www.unscear.org/unscear/en/publications/2008_1.html Accessed 1169

December 31, 2010. 1170

Vano E, Goicolea J, Galvan C, Gonzalez L, Meiggs L, Ten JI, Macaya C. Skin 1171

radiation injuries in patients following repeated coronary angioplasty 1172

procedures. Br J Radiol. 2001 Nov;74(887):1023-31. 1173

Vano E, Kleiman NJ, Duran A, Rehani MM, Echeverri D, Cabrera. M. Radiation 1174

cataract risk in interventional cardiology personnel. Radiat Res, 2010; 1175

174(4):490-495 1176

Verin V, Popowski Y, de Bruyne B, Baumgart D, Sauerwein W, Lins M, Kovacs G, 1177

Thomas M, Calman F, Disco C, Serruys PW, Wijns W, Piessens M, Kurtz J, 1178

Simon R, Delafontaine P, Erbel R. Endoluminal Beta-Radiation Therapy for the 1179

Prevention of Coronary Restenosis after Balloon Angioplasty. N Engl J Med 1180

2001;344:243-249. 1181

Waksman R, Bhargava B, White L, Chan RC, Mehran R, Lansky AJ, Mintz GS, 1182

Satler LF, Pichard AD, Leon MB, Kent KK. Intracoronary beta-radiation 1183

therapy inhibits recurrence of in-stent restenosis. Circulation 2000;101:1895-8. 1184

Williams DO, Holubkov R, Yeh W, Bourassa MG, Al-Bassam M, Block PC, Coady 1185

P, Cohen H, Cowley M, Dorros G, Faxon D, Holmes DR, Jacobs A, Kelsey SF, 1186

King SB, Myler R, Slater J, Stanek V, Vlachos HA, Detre KM. Percutaneous 1187

Coronary Intervention in the Current Era Compared With 1985–1986 The 1188

National Heart, Lung, and Blood Institute Registries. Circulation 1189

2000;102:2945-2951. 1190

Zanchetta M, Maiolino P. Intracardiac echocardiography. Do we need a new 1191

ultrasonographic window? Ital Heart J 2004;5:173-177. 1192

1193

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29

1194

2. THE BIOLOGICAL EFFECTS OF RADIATION 1195

1196

Main Points 1197

1198

Deterministic effects are due to injury in populations of cells, 1199

characterised by a threshold dose and an increase in the incidence and 1200

severity of the reaction as the dose is increased further. Deterministic 1201

effects are also termed tissue reactions. 1202

Stochastic effects are malignant disease and heritable effects for which 1203

the probability of an effect occurring, but not its severity, is regarded as 1204

a function of dose without threshold. 1205

Radiation-induced skin injuries may not become fully manifest until 1206

months after the radiation dose was administered. 1207

The diagnosis of a radiation induced skin injury is often delayed. 1208

The lens of the eye is a radiosensitive tissue. 1209

In the lens of the eye, ionizing radiation typically causes posterior 1210

subcapsular cataract formation. 1211

Surveys of cardiologists and support staff working in catheterization 1212

laboratories have found a high percentage of lens opacities attributable 1213

to occupational radiation exposure when radiological protection tools 1214

have not been used properly. 1215

1216

2.1 Types of radiation effects 1217 1218

(22) The effects of radiation can be classified into two groups: deterministic 1219

effects (harmful tissue reactions) and stochastic effects (cancer and heritable 1220

effects). 1221

(23) Deterministic effects (e.g. skin injury) are largely caused by the 1222

reproductive sterilisation of cells following high radiation doses. The induction of 1223

tissue reactions is generally characterised by a threshold dose. The reason for the 1224

presence of this threshold dose is that radiation-induced reproductive survival of a 1225

critical population of cells in a given tissue needs to be sustained before injury is 1226

expressed in a clinically relevant form. Above the threshold dose the incidence and 1227

severity of the injury, including impairment of the capacity for tissue recovery, 1228

increases with dose (ICRP 103). The threshold is variable, depending on the nature 1229

and condition of the exposed tissue (Balter, 2010). 1230

(24) The injury is not expressed clinically until the cells die as a result of an 1231

unsuccessfully attempt at cell division or differentiation and are lost as part of the 1232

normal process of tissue turnover (Balter, 2010). The incidence as well as the 1233

severity of the injury, including impairment of the capacity for tissue recovery, 1234

increases with dose. After a high radiation dose, the outcome for the affected 1235

individual can be devastating (Balter, 2010). 1236

(25) Eighty percent of reported radiation-induced skin injuries in one large 1237

series were from cardiac procedures (Koenig et al 2001). Nonetheless, cardiologists 1238

often do not recognise that a radiation injury is related to a cardiac procedure, either 1239

because they are unaware of the magnitude of radiation dose delivered or they do 1240

not know that radiation can cause skin injuries. 1241


30

(26) The dose of radiation received by some patients is high and the number of 1242

radiation injury cases is increasing (NCI, 2005). However, most currently practising 1243

interventional cardiologists have no personal experience of a case of radiation 1244

injury. The number of radiation injuries is small compared with the number of 1245

fluoroscopically guided cardiology procedures performed worldwide. 1246

(27) Stochastic effects The accumulation of cellular and animal data relevant to 1247

radiation tumourigenesis has, since 1990, strengthened the view that DNA damage 1248

response processes in single cells are of critical importance to the development of 1249

cancer after radiation exposure. Epidemiological and experimental studies provide 1250

evidence of radiation risk, albeit with uncertainties at doses about 100 mSv or less 1251

(ICRP 103). 1252

(28) These effects are probabilistic—there is no identifiable threshold for 1253

producing the effect. The likelihood of inducing a stochastic effect increases with 1254

dose, but the exact relationship between dose and effect is not known. In the low 1255

dose range, below about 100 mSv, it is scientifically plausible to assume that the 1256

incidence of cancer or heritable effects will rise in direct proportion to an increase in 1257

the equivalent dose in the relevant organs and tissues (the ―linear-non-threshold‖ or 1258

LNT model) (ICRP 103). Dose has no relationship to the severity of the effect. 1259

(29) Children are approximately 2-3 times more sensitive to the stochastic 1260

effects of radiation than adults (ICRP 1991). They also have a longer potential 1261

lifespan than do adults, so they have more time to develop possible radiation related 1262

sequelae. In children, the probability of a fatal cancer per fluoroscopically guided 1263

procedure is estimated at approximately 0.07-0.08%, but this risk may vary widely 1264

depending on patient age, underlying life expectancy and how the procedure is 1265

performed (Martinez et al, 2007, Bacher et al, 2005). 1266

(30) While there is compelling evidence that radiation causes heritable effects 1267

in experimental animals, there continues to be no direct evidence that exposure of 1268

humans to radiation leads to excess heritable disease in offspring (ICRP 103). 1269

1270

2.2 Background 1271 1272

(31) Some months after the discovery of x-rays in 1895, radiation-induced skin 1273

changes were observed (Daniel 1896, Codman 1896). Some early radiologists 1274

suffered severe dermatitis, radiation cancer and amputation of digits. There was a 1275

delay in recognising that x-rays were the cause because they are invisible and do not 1276

cause any sensation during exposure. As noted in ICRP Publication 103, the goal of 1277

preventing these radiation injuries was the impetus for the formation of what is now 1278

the Commission (ICRP 2007). 1279

(32) Following the dramatic rise in the number of percutaneous coronary 1280

interventional procedures, cases of patients with deep skin ulceration and necrosis 1281

were reported in the 1990s (Shope, 1996). In 1994 the U.S. Food and Drug 1282

Administration issued an advisory regarding skin injury from fluoroscopically 1283

guided procedures (FDA 1994). Radiation skin injury has also been reported 1284

following radiofrequency catheter ablations (Vano, 1998). This is of particular 1285

concern because many of these patients are young adults, and some are children. 1286

The Commission drew attention to prevention of skin injuries from interventional 1287

fluoroscopy procedures in Publication 85 (ICRP 2000), and reiterated the 1288

importance of preventing skin injuries in Publication 105 (ICRP 2007). 1289

1290


31

2.3 Radiation Effects and the Skin 1291

1292 (33) The response of the skin to radiation is dose-related and occurs when this 1293

dose is concentrated on one area, usually the site where the x-rays enter the patient. 1294

The term ―absorbed dose‖ is used to assess the amount of radiation to which a tissue 1295

is exposed (see the Glossary). The skin response follows a characteristic pattern, 1296

although the time course is variable (Balter et al, 2010). The threshold doses and 1297

time of appearance for various types of skin injury are summarised in Table 2.1. 1298

(34) Defects in DNA repair genes may predispose individuals to radiogenic 1299

cancer or lower the threshold for the development of deterministic effects. Some 1300

patients with serious and unanticipated radiation injuries may be among the 1% of 1301

the population heterozygous for the ATM gene, an autosomal recessive gene 1302

responsible for ataxia telangiectasia, or may harbour some other ATM abnormality. 1303

(Hymes, 2006, Allan, 2008) Other disorders with a genetic component affecting 1304

DNA breakage or repair also increase radiation sensitivity, including Fanconi 1305

anaemia, Bloom syndrome and xeroderma pigmentosum. Familial polyposis, 1306

Gardner syndrome, hereditary malignant melanoma and dysplastic nevus syndrome 1307

also increase radiation sensitivity (Hymes, 2006). Certain familial cancer syndromes 1308

may increase susceptibility to radiogenic cancer, including neurofibromatosis, Li-1309

Fraumeni syndrome and hereditary retinoblastoma (Allan, 2008). 1310

(35) Autoimmune and connective tissue disorders predispose patients to the 1311

development of severe cutaneous radiation effects in an unpredictable fashion. 1312

These typically occur in association with the high radiation doses administered 1313

during radiation therapy. The aetiology is not known. These disorders include 1314

scleroderma, systemic lupus erythematosus and possibly rheumatoid arthritis.( 1315

(Wagner et al, 1999, Hymes, 2006) Hyperthyroidism and diabetes mellitus are also 1316

associated with increased radiation sensitivity (Koenig Part 1, 2001) Diabetes is 1317

believed to predispose to radiation injury secondary to small vessel vascular disease 1318

and consequent decreased healing capacity (Herold, 1999). A number of drugs 1319

increase radiation sensitivity, including actinomycin D, doxorubicin, bleomycin, 5-1320

fluorouracil and methotrexate (Koenig Part 1, 2001) Again, this effect is usually 1321

seen only with the high radiation doses delivered during radiation therapy. 1322

(36) It is apparent from the foregoing and from Table 2.1 that there are no 1323

rigid thresholds for dose or time of appearance of radiation-induced skin changes, 1324

because individuals vary in their radio-sensitivity and radio-responsiveness (Balter 1325

et al, 2010). These ranges are shown graphically in Figure 2.1. In the discussion 1326

below, threshold doses are given for an average person, but it should be understood 1327

that these will vary from individual to individual. For most patients, clinically 1328

important skin reactions occur only when the absorbed skin dose is greater than 1329

5 Gy (Balter et al, 2010; ICRP Tissue Reactions, 2011a). 1330

1331


32

Table 2.1: Tissue reactions from a single-delivery radiation dose to the skin of the neck, torso, pelvis, buttocks or 1332 arms. (from Balter et al, 2010) 1333

- This table is applicable to the normal range of patient radiosensitivities in the absence of mitigating or aggravating physical or clinical factors. - Skin dose refers to absorbed skin dose (including backscatter). This quantity is not the reference air kerma (Ka,r) described by the Food and Drug Administration (21 CFR § 1020.32 (2008)) or the International Electrotechnical Commission.(IEC, 2010) - This table does not apply to the skin of the scalp. - Abrasion or infection of the irradiated area is likely to exacerbate radiation effects. - The dose and time bands are not rigid boundaries. Signs and symptoms are expected to appear earlier as the skin dose increases.

Band

Single-site Acute Skin-Dose Range

(Gy)1

NCI Skin

Reaction Grade*

Approximate time of onset of effects

(4) Prompt < 2 weeks

(5) Early 2 – 8 weeks

Mid term 6 – 52 weeks

Long term > 40 weeks

A1 0-2 N/A No observable effects expected

A2 2-5 1 - Transient erythema - Epilation - Recovery from hair loss (6) - None expected

B 5-10 1

- Transient erythema - Erythema, epilation - Recovery. - At higher doses;

prolonged erythema, permanent partial epilation

(7) - Recovery. - At higher doses dermal

atrophy/induration.

C 10-15 1-2

- Transient erythema

- Erythema, epilation. - Possible dry or moist

desquamation

(8) - Recovery from desquamation

(9) - Prolonged erythema. - Permanent epilation.

(10) - Telangiectasia2

- Dermal atrophy/induration. - Skin likely to be weak.

D > 15 3-4

- Transient erythema - After very high doses,

edema and acute ulceration; long-term surgical intervention likely to be required.

- Erythema, epilation.

(11) - Moist desquamation

(12) - Dermal atrophy, - Secondary ulceration due

to failure of moist desquamation to heal; surgical intervention likely to be required.

- At higher doses, dermal necrosis; surgical intervention likely to be required..

(13) - Telangiectasia2.

- Dermal atrophy/induration, - Possible late skin breakdown. - Wound might be persistent and

progress into a deeper lesion. - Surgical intervention likely to be

required.

1 Skin dosimetry is unlikely to be more accurate than ± 50%

2 Refers to radiation-induced telangiectasia. Telangiectasia associated with an area of initial moist desquamation or the healing of

ulceration may be present earlier. *NCI = U.S. National Cancer Institute


33

1334

1335

1336 1337

1338

Figure 2.1: Graphical representation of data in Table 2.1 showing overlap in the skin 1339

effects with both dose and time. 1340

1341

1342

(37) The lowest dose that may produce a noticeable skin change in individuals with 1343

average radiation sensitivity is conventionally considered to be 2 Gy. Histamine-like 1344

substances are activated and dilate capillaries, resulting in reddening (transient erythema). 1345

This usually occurs within hours of exposure and fades after 24 hours. This effect is 1346

likely to be under-reported due to its short duration. 1347

(38) After a dose of 6 Gy, a second hyperaemic phase (main erythema) commences 1348

at approximately 10 days. This phase may be apparent earlier after doses > 6 Gy. It 1349

results from the destruction of proliferating basal cells in the epidermis. The patient may 1350

complain of burning, tenderness and itching, and the skin becomes warm and 1351

oedematous. The erythema usually peaks at 2 weeks and fades by 4 weeks (Koenig et al, 1352

2001). 1353

(39) If doses exceed 10 Gy, the erythema may be more prolonged, with 1354

hyperpigmentation. At skin doses > 14 Gy the inflammation can progress to dry 1355

desquamation—the erythematous skin is covered with scales and flakes of corneum, with 1356

an appearance resembling sunburn. Moist desquamation occurs at doses of about 18 Gy. 1357

The skin blisters and sloughs with weeping of serum from the deep cutaneous layers. 1358


34

This is associated with considerable pain and the skin becomes susceptible to infection. 1359

Topical antibiotics are often required (Shack et al, 1987). The proliferative cells in the 1360

basal layer of the epidermis are damaged and reduced in number. Desquamation usually 1361

appears 4 weeks after exposure and can last many weeks, particularly if secondary 1362

infection occurs. 1363

(40) A late phase of erythema can develop 8-10 weeks after radiation exposure of 1364

approximately 15 Gy. The skin has a mauve or dusky appearance. A skin dose of about 1365

18 Gy may result in vascular insufficiency of the dermis, leading to ischemic dermal 1366

necrosis 10-16 weeks following exposure. The damage is greater at higher doses (Koenig 1367

et al, 2001). 1368

(41) Dermal atrophy occurs after prolonged erythema, particularly when associated 1369

with moist desquamation. This is typically seen in two phases, initially at 3 months and 1370

then at 1 year. At doses above 10 Gy, telangiectasia may also develop because of dilation 1371

of the dermal capillaries. This is often a late phenomenon, occurring more than a year 1372

after exposure, but has been noted earlier and can increase over time (Turreson et al, 1373

1986). Trauma may precipitate late necrosis in skin that shows these late changes. The 1374

threshold for this is approximately12 Gy, so it may be seen in the absence of earlier skin 1375

desquamation. 1376

(42) The diagnosis of a radiation-induced skin injury is often delayed because these 1377

lesions are relatively rare and the cause may not be recognized. Also, there is often a 1378

latent period of many months before the lesion is fully apparent (Balter et al, 2010). 1379

Patients often seek care from a dermatologist, rather than the physician who performed 1380

the interventional procedure. As a result, the history of fluoroscopy may be overlooked 1381

or considered irrelevant (Frazier et al 2007). Skin biopsy is frequently performed, 1382

although the results are not specific for radiation injury and can lead to a non-healing 1383

ulcer, as can other forms of trauma. Misdiagnoses are often made, including contact 1384

dermatitis from an electrode pad, allergy to adhesive tape or skin disinfectant, drug 1385

eruption, viral or bacterial infection and even insect bite. The deep pain associated with 1386

an injury may lead to extensive chest and abdominal evaluation (Vlietstra et al 2004). 1387

Severe injuries may extend into muscle (Monaco et al, 2003). 1388

(43) Skin cancer directly related to radiation from an interventional procedure has 1389

not been reported. Cases of basal cell carcinoma have been documented following x-ray 1390

treatment for scalp ringworm (Shore 2002) with a relative risk of 3.6 after a scalp dose of 1391

4.8 Gy. The relative risk of skin cancer in Chinese medical x-ray workers has been 1392

estimated at 4.1 in a cohort studied from 1950 – 1995. (Wang 2002) 1393

1394

2.4 The Lens of the Eye and Radiation 1395

1396 (44) The prevalence of cataract is difficult to estimate, as it depends in part on the 1397

definition of cataract. The Framingham Eye Study (Kahn et al, 1977) found a 91% 1398

prevalence in 75-85 year olds, although this figure was reduced to 46% if ‗modest visual 1399

deficit‘ is added to the definition. A more recent Spanish study gave a prevalence of 1400

cataract and decreased visual acuity of more than 60% of 75 year olds. (Acosta et al, 1401

2006) 1402


35

(45) The majority of lens opacities that are not due to radiation are associated with 1403

cortical changes in the superficial substance of the lens. The lens is a radiosensitive 1404

tissue. Ionizing radiation typically causes posterior subcapsular (PSC) cataract formation 1405

(Figure 2.2). Unlike an age-related cataract, which usually interferes initially with visual 1406

acuity, a PSC cataract reduces contrast sensitivity before reducing visual acuity. 1407

1408

1409

1410

1411

1412

1413

1414

1415

1416

1417

1418

1419

1420

1421

1422

1423

1424

1425

1426

1427

Figure 2.2: a) A radiation-induced posterior subcapsular (PSC) cataract is shown as a 1428

central black shadow at the posterior aspect of the lens. b) Retroillumination photograph 1429

of a PSC cataract at the posterior aspect of the lens. This causes glare and poor vision in 1430

bright light conditions as well as poor reading vision. (From RSNA News, June 2004 1431

(http://www.rsna.org/Publications/rsnanews/upload/jun2004.pdf)) [Permission to be 1432

requested from RSNA] 1433

1434

(46) The response of the lens to radiation has traditionally been considered a 1435

deterministic effect. The threshold dose for detectable human lens opacities has been 1436

considered to be 2 Sv for a single acute exposure and 5 Sv for protracted exposure. For 1437

cataract with visual impairment, the thresholds have been considered to be 5 Sv and 8 Sv 1438

respectively. (ICRP 1991, NCRP 1993). More recent data in populations exposed to 1439

lower doses of radiation suggest that dose related lens opacification occurs at exposures 1440

significantly lower than 2 Sv, and that there may be no dose threshold. (Worgul et al, 1441

2007, Kleiman 2007, NCRP 168, 2010, Shore 2010, ICRP XXX [Tissue Reactions], 1442

2011a) 1443

(47) There have been reports of radiation-induced cataracts in interventionalists 1444

who have performed procedures for a number of years, and of doses to the lens 1445

approaching the annual limit of 150 mSv during angiographic procedures (Figure 2.3) 1446

http://www.rsna.org/Publications/rsnanews/upload/jun2004.pdf


36

(Vano et al, 1998, Pages 2000, Hidajat 2006, Vano et al 2010). Recent studies have 1447

shown that with typical reported interventional workloads the radiation dose to the lens 1448

may exceed the current threshold for deterministic effects after several years of work, if 1449

radiological protection tools are not used (Vano et al, 2008, Kim et al, 2008) Several 1450

surveys of cardiologists and support staff working in catheterization laboratories, 1451

conducted with coordination provided by the International Atomic Energy Agency 1452

(IAEA) in Latin America and Asia, have found a high percentage of lens opacities 1453

attributable to occupational radiation exposure (Vano et al, 2010, Ciraj-Bjelac et al, 1454

2010). 1455

(48) These recent data and the mechanistic uncertainties regarding cataract 1456

development have highlighted the need for a detailed reappraisal of the radiosensitivity of 1457

the lens of the eye. This issue is addressed in ICRP Publication XXX, on Tissue 1458

Reactions and Other Non-Cancer Effects of Radiation and its Statement on Tissue 1459

Reactions (ICRP, 2011a, 2011b). The previous Commission recommendation (ICRP, 1460

1991) of a dose limit of 150 mSv per year for occupational exposure in a planned 1461

exposure situation (e.g., occupational exposure of interventionalists) has been changed. 1462

The Commission now recommends that the lens dose limit for chronic occupational 1463

exposure should be 20 mSv in a year, averaged over defined periods of 5 years, with no 1464

single year exceeding 50 mSv, i.e. the same as the annual whole body limit for workers 1465

(ICRP, 2011a, 2011b). 1466

(49) The Commission now considers the threshold in absorbed dose to the lens of 1467

the eye to be 0.5 Gy (ICRP, 2011b). The Commission judges, based on existing 1468

evidence, that an acute dose of up to around 100 mGy produces no functional impairment 1469

of tissues, including the lens of the eye with respect to cataract, although the use of a 1470

threshold model remains uncertain for this tissue (ICRP, 2011a). 1471

1472

1473

1474 1475

Figure 2.3: PSC cataract in the eye of an interventionist using an old x-ray system and 1476

high scatter radiation from improper working conditions (E. Vano BJR 1998) 1477


37

1478

1479

2.5 Cardiovascular effects of radiation exposure 1480 1481

(50) The mechanisms of heart radiation damage include inflammatory processes, in 1482

particular after low doses, and after higher doses there is a progressive reduction in the 1483

number of patent capillaries eventually leading to ischemia, myocardial cell death and 1484

fibrosis, accelerated atherosclerosis in major blood vessels, decreased cardiac function, 1485

and fatal congestive heart failure. There are no known mitigators of radiation-induced 1486

cardiovascular disease (ICRP, 2011). 1487

(51) Analyses of the atomic bomb survivors have shown that radiation doses above 1488

0.5 Gy are associated with an elevated risk of both stroke and heart disease (Shimizu et 1489

al, 2010). These findings are consistent with other studies that demonstrated an increased 1490

risk of heart disease after radiation therapy to the chest (Bhatti et al, 2008). There is 1491

compelling evidence that ionizing radiation in the doses using for radiation therapy can 1492

increase the risk of heart disease (McGale and Darby, 2008). 1493

(52) Radiation induced heart disease can occur as a result of both microvascular 1494

damage to the myocardium, leading to focal myocardial degeneration and fibrosis, and 1495

accelerated atherosclerosis in major blood vessels. Cardiovascular radiation effects have 1496

been reported to occur at doses > 0.5 Gy (ICRP, 2011). Although uncertainty remains, 1497

medical practitioners should be aware that the absorbed dose threshold for circulatory 1498

disease may be as low as 0.5 Gy to the heart (ICRP, 2011b). In some complex 1499

fluoroscopically guided cardiac procedures, organ doses may be > 0.5 Gy. These 1500

radiation effects need to be considered during the optimization process. 1501

(53) At lower doses (below 0.5 Gy) the relationship between radiation dose and 1502

increased cardiovascular risk is unclear (Shimizu et al, 2010). McGeoghegan and 1503

colleagues (2008) observed an association between mortality from non-cancer causes of 1504

death, particularly circulatory system disease, and exposure to ionizing radiation in their 1505

analysis of 42,000 radiation workers with low-dose, long-term radiation exposure. Other 1506

studies have shown mixed results (McGale and Darby, 2008). Recent reviews of 1507

epidemiological studies of populations medically, occupationally or environmentally 1508

exposed to relatively low-dose radiation showed that there was substantial heterogeneity 1509

in the association between radiation exposure and circulatory disease, with respect to the 1510

risk per unit radiation dose, possibly resulting from confounding factors or bias (ICRP, 1511

2011). As there is no clear understanding of the underlying biological mechanisms, it is 1512

difficult to interpret these mixed results (Dauer et al, 2010). 1513

1514

2.6 Occupational radiation exposure and intracranial neoplasms 1515 1516

(54) Ionizing radiation is one of the few established causes of neural tumours 1517

(Yonehara et al., 2004). Preston and colleagues studied the incidence of nervous system 1518

tumours in atomic bomb survivors (Preston et al., 2007; Preston et al., 2002). They found 1519

a significant dose-related excess of nervous system tumours. They concluded that 1520

exposure to doses of radiation as low as < 1 Sv is associated with an elevated incidence 1521


38

of nervous system tumours (Preston et al., 2002). It is clear that in children, radiation 1522

exposure is associated with the development of brain cancer, but the relationship in 1523

individuals exposed as adults is much less clear. The association between benign 1524

intracranial tumours and radiation appears to be substantially stronger than for malignant 1525

tumours (UNSCEAR, 2000). However, the BEIR-VII report does not explicitly present 1526

Lifetime Attributable Risk (LAR) for brain cancer incidence or mortality (NRC, 2006). 1527

What is clear is that for operators and staff, the brain is one of the least protected organs 1528

during interventional fluoroscopy procedures. 1529

(55) Radiation dose to the brain in fluoroscopists has not been well studied. Wenzl 1530

noted that cardiologists may receive the highest radiation doses of any specialists who 1531

use fluoroscopy for interventional procedures (Wenzl, 2005). Renaud determined that 1532

the annual exposure to cardiologists‘ heads was approximately 20 – 30 mSv (Renaud, 1533

1992). However, Renaud‘s study was performed with data from 1984 through 1988, 1534

when both cardiac interventions and fluoroscopic equipment were less sophisticated than 1535

they are now. 1536

(56) Finkelstein suggested that the occurrence of brain tumours in two Toronto 1537

cardiologists in a one-year period might indicate that they were radiation-induced 1538

(Finkelstein, 1998). Epidemiologic evidence for radiation-induced brain cancer in 1539

fluoroscopists is suggestive, but by no means conclusive. In 1975, Matanoski and 1540

colleagues found that the death rate from brain cancer in American radiologists was 1541

almost 3 times that of other medical specialists who did not use radiation (Matanoski et 1542

al., 1975). In a Swedish case-control study of 233 patients with brain tumours, Hardell 1543

and colleagues reported that work as a physician using fluoroscopy increased the risk of 1544

developing a brain tumour, with an odds ratio of 6.0 (95% confidence interval, 0.62-1545

57.7), but there were only 3 such individuals among the 233 cases (Hardell et al., 2001). 1546

No increased risk was found for other health care workers. In a case-control study of 476 1547

individuals diagnosed with gliomas between 1991 and 1994 in the San Francisco area, 1548

Carozza and colleagues observed an increased risk in physicians and surgeons (odds ratio 1549

3.5, 95% confidence interval 0.7-17.6) (Carozza et al., 2000). There were only 6 1550

physicians in the group, and the authors suggested that the increased risk might be due to 1551

occupational exposure to numerous biologic agents and chemicals as well as to radiation. 1552

On the other hand, Blettner and colleagues conducted a case-control study in Germany of 1553

844 patients with brain tumours and 1737 control subjects, using self-reported medical 1554

and occupational data (Blettner et al., 2007). More than 2/3 of the 91 participants 1555

occupationally exposed to radiation were in the medical field (physicians, nurses, 1556

radiographers). Blettner and colleagues found no significant risk of brain tumours as a 1557

result of exposure to medical ionizing radiation. Karipidis and colleagues conducted a 1558

case-control study in Australia of 416 patients with gliomas and 422 controls and found 1559

no evidence of an association between gliomas and ionizing radiation (Karipidis et al. 1560

2007). 1561

1562

2.7 References 1563 1564


39

Acosta R, Hoffmeister L, Roman R, Comas M, Castilla M, Castells X. Systematic 1565

review of population-based studies of the prevalence of cataracts. Arch Soc Esp 1566

Oftalmol 2006; 81: 509-516 1567

Allan JM. Genetic susceptibility to radiogenic cancer in humans. Health Phys 2008; 1568

95:677-686. 1569

Bacher K, Bogaert E, Lapere R, De Wolf D, Thierens H. Patient-specific dose and 1570

radiation risk estimation in pediatric cardiac catheterization. Circulation. 2005 Jan 1571

4;111(1):83-9. 1572

Balter S, Hopewell JW, Miller DL, Wagner LK, Zelefsky MJ. Fluoroscopically guided 1573

interventional procedures: A review of radiation effects on patients' skin and hair. 1574

Radiology 2010; 254:326-41. 1575

Bhatti P, Sigurdson AJ, Mabuchi K. Cam low-dose radiation increase risk of 1576

cardiovascular disease? Lancet 2008; 372:697-699. 1577

Blettner M., Schlehofer B., Samkange-Zeeb F., Berg G., Schlaefer K., Schüz J. (2007) 1578

Medical exposure to ionising radiation and the risk of brain tumours: Interphone 1579

study group, Germany. Eur J Cancer 43:1990-8. 1580

Carozza S.E., Wrensch M., Miike R., Newman B., Olshan A.F., Savitz D.A., Yost M., 1581

Lee M. (2000) Occupation and adult gliomas. Am J Epidemiol 152:838-46. 1582

Finkelstein M.M. (1998) Is brain cancer an occupational disease of cardiologists? Can J 1583

Cardiol 14:1385-8. 1584

Ciraj-Bjelac O, Rehani MM, Sim KH, Liew HB, Vano E, Kleiman NJ. Risk for radiation 1585

induced cataract for staff in interventional cardiology: Is there reason for concern? 1586

Catheter Cardiovasc Interv 2010;76(6):826-834. 1587

Codman EA. The cause of burns from x-rays. (letter) Bos Med Surg J 1896; 136:610-1588

611 1589

Daniel J. The x-rays. (letter) Science 1896; 3:562 1590

Dauer LT, Brooks AL, Hoel DG, Morgan WF, Stram D, Tran P. Review and evaluation 1591

of updated research on the health effects associated with low-dose ionising radiation. 1592

Radiat Prot Dosim 2010; 140(2):103-136 1593

Frazier TH, Richardson JB, Fabre VC, Callen JP. Fluoroscopy-induced chronic 1594

radiation skin injury: a disease perhaps often overlooked. Arch Dermatol 2007; 1595

143(5): 637-640 1596

Hardell L., Hansson Mild K., Påhlson A., Hallquist A. (2001) Ionizing radiation, cellular 1597

telephones and the risk for brain tumours. Eur J Cancer Prev 10:523-9. 1598

Herold DM, Hanlon AL, Hanks GE. Diabetes mellitus: a predictor for late radiation 1599

morbidity. Int J Radiat Oncol Biol Phys 1999; 43: 475-479 1600

Hidajat N, Wust P, Felix R, Schroder RJ. Radiation exposure to patient and staff in 1601

hepatic chemoembolization: risk estimation of cancer and deterministic effects. 1602

Cardiovasc Intervent Radiol 2006; 29(5): 791-796 1603

Hymes SR, Strom EA, Fife C. Radiation dermatitis: clinical presentation, 1604

pathophysiology, and treatment 2006. J Am Acad Dermatol 2006;54:28-46 1605

IEC. Report 60601 Medical electrical equipment - Part 2-43: Particular requirements for 1606

the safety of X-ray equipment for interventional procedures. 2nd ed. Geneva, 1607

Switzerland: International Electrotechnical Commission; 2010. 1608


40


Radiological Protection. ICRP Publication 60. Ann ICRP 1991; 21(1-3):1-201 1610

ICRP, 2000. Avoidance of radiation injuries from medical interventional procedures. 1611

ICRP Publication 85. Ann ICRP 30:7-67. 1612

ICRP, 2007a. The 2007 Recommendations of the International Commission on 1613

Radiological Protection. ICRP Publication 103. Ann ICRP 37(2-4):1-332 1614

ICRP, 2007b.. Radiological protection in medicine. ICRP Publication 105. Ann ICRP 1615

37:1-63 1616

ICRP Protection 2011a. Tissue Reactions and Other Non-Cancer Effects of Radiation. 1617

ICRP Publication XXX. Ann ICRP 2011; in press 1618

ICRP 2011b. Statement on Tissue reactions. Approved by the Commission on April 1619

21, 2011. Available at 1620

http://www.icrp.org/docs/ICRP%20Statement%20on%20Tissue%20Reactions.pdf 1621

Accessed May 9, 2011. (in press) 1622

Kahn, HA, Liebowitz HM, Ganley JP, Kini MM, Colton T, Nickerson RS, Dawber TR. 1623

The Framingham Eye Study. I. Outline and major prevalence findings. Am J 1624

Epidemiol 1977; 106(1): 17-32 1625

Karipidis KK, Benke G, Sim MR, Kauppinen T, Giles G. (2007) Occupational exposure 1626

to ionizing and non-ionizing radiation and the risk of glioma. Occup Med (Lond) 1627

57:518-524. 1628



procedures. Health Phys 2008;94:211-227. 1631

Kleiman NJ. Radiation cataract. In: Working Party on Research Implications on Health 1632

and Safety Standards of the Article 31 Group of Experts, ed. Radiation Protection 1633

145 EU Scientific Seminar 2006 New insights in radiation risk and basic safety 1634

standards. Brussels: European Commission; 2007:81-95. Available at 1635

http://ec.europa.eu/energy/nuclear/radioprotection/publication/doc/145_en.pdf 1636

Accessed July 28, 2010 1637

Koenig TR, Wolff D, Mettler FA, Wagner LK. Skin injuries from fluoroscopically 1638

guided procedures: Part 1, Characteristics of radiation injury. AJR 2001; 177: 3-11 1639

Martinez LC, Vano E, Gutierrez F, Rodriguez C, Gilarranz R, Manzanas MJ. Patient 1640

doses from fluoroscopically guided cardiac procedures in pediatrics. Phys Med Biol 1641

2007; 52: 4749-4759. 1642

Matanoski G.M., Seltser R., Sartwell P.E., Diamond E.L., Elliott E.A. (1975) The 1643

current mortality rates of radiologists and other physician specialists: specific causes 1644

of death. Am J Epidemiol 101:199-210. 1645

McGale P, Darby SC. Commentary: A dose-response relationship for radiation-induced 1646

heart disease—current issues and future prospects. Int J Epidemiol 2008; 37:518-1647

523 1648

McGeoghegan D, Binks K, Gillies M, Jones S, Whaley S. The non-cancer mortality 1649

experience of male workers at British Nuclear Fuels plc, 1946-2005. Int J Epidemiol 1650

2008; 37:506-518 1651

http://www.icrp.org/docs/ICRP%20Statement%20on%20Tissue%20Reactions.pdf

http://ec.europa.eu/energy/nuclear/radioprotection/publication/doc/145_en.pdf


41

Monaco JL, Bowen K, Tadros PN, Witt PD. Iatrogenic deep musculocutaneous radiation 1652

injury following percutaneous coronary intervention. J Invasive Cardiol 1653

2003;15:451-3. 1654

National Cancer Institute, 2005. Interventional fluoroscopy: reducing radiation risks for 1655

patients and staff. NIH Publication No. 05-5286. National Cancer Institute, 1656

Bethesda, MD. Available at: http://www.cancer.gov/images/Documents/45bae965-1657

697a-4de8-9dae-b77222e0e79d/InterventionalFluor.pdf Accessed December 31, 1658

2010. 1659

National Council on Radiation Protection and Measurements. Limitation of exposure to 1660

ionizing radiation. NCRP Report 116. Bethesda, MD: National Council on Radiation 1661



management for fluoroscopically guided interventional medical procedures. NCRP 1664

Report No. 168. Bethesda, MD: National Council on Radiation Protection and 1665

Measurements; 2010. 1666

NRC. (2006) Health risks from exposure to low levels of ionizing radiation: BEIR-VII 1667

Phase 2 National Academy Press, Washington, DC. 1668

Pages J. Effective dose and dose to the crystalline lens during angiographic procedures. 1669

JBR-BTR 2000; 83:108-110 1670

Preston D.L., Ron E., Tokuoka S., Funamoto S., Nishi N., Soda M., Mabuchi K., 1671

Kodama K. (2007) Solid cancer incidence in atomic bomb survivors: 1958-1998. 1672

Radiat Res 168:1-64. 1673

Preston D.L., Ron E., Yonehara S., Kobuke T., Fujii H., Kishikawa M., Tokunaga M., 1674

Tokuoka S., Mabuchi K. (2002) Tumors of the nervous system and pituitary gland 1675

associated with atomic bomb radiation exposure. J Natl Cancer Inst 94:1555-63. 1676

Renaud L. (1992) A 5-y follow-up of the radiation exposure to in-room personnel during 1677

cardiac catheterization. Health Phys 62:10-15. 1678

Shack RB, Lynch JB. Radiation dermatitis. Clin Plast Surg 1987; 14: 391-401 1679

Shimizu Y, Kodama K, Nishi N, Kasagi F, Suyama A, Soda M, Grant EJ, Sugiyama H, 1680

Sakata R, Moriwaki H, Hayashi M, Konda M, Shore RE. Radiation exposure and 1681

circulatory disease risk: Hiroshima and Nagaski atomic bomb survivor data, 1950-1682

2003. BMJ 2010; 340:b5349 1683

Shope, T.B., 1996. Radiation-induced skin injuries from fluoroscopy. Radiographics 16, 1684

1195-1199. 1685

Shore RE, Moseson M, Xue X, Tse Y, Harley N, Pasternack BS. Skin cancer after x-ray 1686

treatment for scalp ringworm. Radiat Res 2002: 157 (4): 410-418 1687

Shore, R.E., Neriishi, K., Nakashima, E., 2010. Epidemiological studies of cataract risk 1688

at low to moderate radiation doses: (not) seeing is believing. Radiat. Res. 174, 889-1689

894. 1690

Turreson I, Notter G. The predictive value of skin telangiectasia for late radiation effect 1691

in different normal tissues. Int J Radiat Oncol Biol Phys 1986; 12 603-609 1692

UNSCEAR. (2000) Sources and effects of ionizing radiation. United Nations, New 1693

York. 1694

http://www.cancer.gov/images/Documents/45bae965-697a-4de8-9dae-b77222e0e79d/InterventionalFluor.pdf



42

United States Food and Drug Administration . Public Health Advisory. Avoidance of 1695

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procedures. Rockville, MD: Center for Devices and Radiological Health, United 1697

States Food and Drug Administration, 1994 Available at 1698

http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotificati1699

ons/ucm063084.htm Accessed July 29, 2010. 1700

Vano E, Arranz L, Sastre JM, Moro C, Ledo A, Garate MT, Minguez I. Dosimetric and 1701

radiation protection considerations based on some cases of patient skin injuries in 1702

interventional cardiology. Br J Radiol 1998; 71: 510-516 1703

Vano E, Gonzalez L, Beneytez F, Moreno F. Lens injuries induced by occupational 1704

exposure to non-optimized interventional radiology laboratories. Br J Radiol 1998; 1705

71: 728-733 1706

Vano E, Gonzalez L, Fernandez M, Haskal ZJ. Eye lens exposure to radiation in 1707

interventional suites: caution is warranted. Radiology 2008; 248: 945-953 1708


cataract risk in interventional cardiology personnel. Radiat Res, 2010; 174(4):490-1710

495 1711

Vlietstra RE, Wagner LK, Koenig T, Mettler F. Radiation burns as a severe complication 1712

of fluoroscopically guided cardiological interventions. J Int Cardiol 2004; 17(3): 1-1713

12 1714

Wagner LK, McNesse MD, Marx MV, Siegel EL. Severe skin reactions from 1715

interventional fluoroscopy: case report and review of literature. Radiology 1999; 1716

213: 773-776 1717

Wang JX, Zhang LA, Li BX, Zhao YC, Wang ZQ, Zhang JY, Aoyama T. Cancer 1718

incidence and risk estimation among medical x-ray workers in China, 1950-1955. 1719

Health Phys 2002; 82(4): 455-466 1720

Wenzl T.B. (2005) Increased brain cancer risk in physicians with high radiation 1721

exposure. Radiology 235:709-10; author reply 710-1. 1722

Worgul BV, Kundiyev YI, Sergiyenko NM, Chumak VV, Vitte PM, Medvedovsky C, 1723

Bakhanova EV, Junk AK, Kryrychenko OY, Musijachenko NV, Shylo SA, Vitte OP, 1724

Xu S, Xue X, Shore RE. Cataracts among Chernobyl clean-up workers: implications 1725

regarding permissible eye exposures. Radiat Res 2007; 167(2): 233-243 1726

Yonehara S., Brenner A.V., Kishikawa M., Inskip P.D., Preston D.L., Ron E., Mabuchi 1727

K., Tokuoka S. (2004) Clinical and epidemiologic characteristics of first primary 1728

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survivors in Hiroshima and Nagasaki, 1958-1995. Cancer 101:1644-54. 1730

1731

1732

1733

http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotifications/ucm063084.htm

http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotifications/ucm063084.htm


43

3. CLINICAL EXAMPLES OF DETERMINISTIC INJURY AFTER 1734

FLUOROSCOPICALLY GUIDED CARDIAC PROCEDURES 1735

1736

Main Points 1737

1738

There is increasing concern about skin radiation dose levels in cardiology. 1739

The cases presented in this chapter provide a clinical context and illustrate 1740

skin changes due to radiation injury. 1741

Deterministic injuries may extend into deeper tissues and can cause symptoms 1742

that persist for years. 1743

Deterministic injuries may be accompanied by an increase in stochastic risk. 1744

1745

3.1 Introduction 1746

1747 (57) There is increasing concern about skin radiation dose levels in cardiology. 1748

This is because of the discovery of deterministic injuries in patients who have undergone 1749

long procedures using suboptimal equipment, performed by individuals inadequately 1750

trained in radiological protection (UNSCEAR, 2010). However, high skin doses can 1751

occur in obese patients, or patients undergoing complex interventions, even when the 1752

procedure is performed by an experienced, well-trained operator using modern, well-1753

maintained equipment (Suzuki, 2008; Bryk, 2006). 1754

(58) The information presented in Chapter 2 (section 2.3) on the radiobiology of the 1755

skin can be difficult to interpret without a clinical context. The cases presented in this 1756

chapter provide that clinical context and illustrate the skin changes discussed in Chapter 1757

2. It should be apparent that these injuries can be severe and debilitating. Some patients 1758

will require life-long therapy and observation. Treatment often requires a 1759

multidisciplinary team working in a specialized centre. Pain management and 1760

psychological support are important components of treatment. 1761

(59) Methods to optimize patient radiation dose and minimize skin dose are 1762

described in Chapter 5 and listed in Table 5.1, but are repeated here because of their 1763

importance. Limit fluoroscopy time and the number of cine frames to the least number 1764

possible for successful completion of the procedure. Monitor patient radiation dose 1765

during the procedure. Use fluoroscopy equipment with pulsed fluoroscopy and use the 1766

lowest pulse rate that provides adequate fluoroscopic guidance. Use the lowest 1767

fluoroscopic and cine dose rates necessary for each stage of the procedure. When 1768

possible, slightly rotate the gantry so that the entrance beam is periodically directed at a 1769

different entrance skin site. Keep the image receptor (image intensifier or flat panel 1770

detector) as close as possible to the patient, and keep the x-ray tube as far away as 1771

possible from the entrance skin site. 1772

1773

1774

1775

1776

1777


44

3.2 Case 1 (Vliestra et al, 2004) 1778 1779

(60) A 53-year-old man weighing 141 kg (310 lbs) had two previous percutaneous 1780

transluminal coronary angioplasties (PTCA) 3 years earlier and now presented with 1781

unstable angina. A repeat coronary angiogram was followed immediately by PTCA of 1782

the distal circumflex artery. The procedure included use of the left anterior oblique 1783

(LAO) projection, biplane cinefluorography runs, high dose fluoroscopy mode and a total 1784

fluoroscopy time of 51.4 minutes. The estimated skin dose was 22 Gy. 1785

(61) The patient presented six weeks later with a painful, itchy rash on his lower 1786

back in a square pattern (Fig. 3.1). This area developed into a painful ulcer. 1787

Debridement and skin grafting were required six months after the PTCA. Local 1788

discomfort persists. 1789

1790

1791

1792

1793

1794

1795

1796

1797

1798

1799

1800

1801

1802

1803

1804

1805

1806

1807

1808

1809

Figure 3.1 Case 1. See text for details. Reprinted from Vliestra, 2004. (Permission 1810

needed) 1811

1812

1813

3.3 Case 2 (Koenig et al, 2001) 1814

1815 (62) A 75 year old woman had two previous coronary angiograms, followed by 1816

PTCA for a 90% stenosis of the right coronary artery. Ten months after the procedure 1817

she developed a skin lesion (Fig. 3.2). Skin dose estimates are not available. 1818

1819


45

1820

1821

1822

1823

1824

1825

1826

1827

1828

1829

1830

1831

1832

1833

1834 Figure 3.2 Case 2. The right lateral chest demonstrates both hyper- and 1835

hypopigmentation, in addition to skin atrophy and telangiectasia. Reprinted from Koenig, 1836

2001. (Permission needed) 1837

1838

1839

3.4 Case 3 (Koenig et al, 2001) 1840

1841 (63) A 49-year-old woman presented with an 8-year history of supraventicular 1842

tachycardia. Radiofrequency catheter ablation was performed. During the procedure her 1843

right arm was in the x-ray beam near the port. The separator (spacer) had been removed 1844

from the tube housing. Fluoroscopy time was approximately 20 minutes. Skin dose data 1845

are not available. She presented 3 weeks later with a skin lesion on her right elbow (Fig. 1846

3.3). If the patient‘s arm had been positioned outside the x-ray beam the injury could 1847

have been prevented or its severity decreased. 1848

1849


46

1864

1865

1866

1867

1868

1869

1870

1871

1872

1873

1874

1875

1876

1877

Figure 3.3 Case 3. See text for details. A) 3 weeks: Area of sharply demarcated 1878

erythema. B) 5 months: Tissue necrosis. C) 6½ months: Deep ulceration with exposure of 1879

the bone. D) Following surgical flap. Reprinted from Koenig, 2001. (Permission 1880

needed) 1881

1882

3.5 Case 4 (Vliestra et al, 2004) 1883

1884 (64) A 38-year-old man weighing 114 kg (250 lbs) was diagnosed with Wolff-1885

Parkinson-White syndrome. An attempt at radiofrequency ablation using biplane 1886

fluoroscopy was unsuccessful. A few weeks after the procedure, the patient developed 1887

areas of brownish-red discolouration on his back, which resolved. A second unsuccessful 1888

ablation procedure was performed 2½ months later, with reappearance of the skin 1889

discolouration after 1 week. The physician thought the skin lesion was due to the 1890

grounding pad used for radiofrequency ablation rather than to radiation. A third 1891

unsuccessful ablation procedure was performed; skin lesions appeared 8 days later (Fig 1892

3.4). Each of the three procedures used more than 100 min of fluoroscopy time. Skin 1893

dose estimates are not available. The severe injury to the right arm was due to its 1894

position. If the arm had been positioned away from the entrance x-ray beam, the injury 1895

might have been avoided. 1896

1897

1898

1899

1900

1901

1902

1903

1904

1905

1906

1907


47

1908

1909 Figure 3.4 Case 4. The right-sided lesions show desquamation. The erythema on the 1910

back healed into discoloured scars. The right arm lesion, closer to the x-ray beam, 1911

developed necrosis and required a skin graft. Reprinted from Vliestra, 2004. (Permission 1912

needed) 1913

1914

3.6 Case 5 (Vañó et al, 1998) 1915 1916

(65) A 17-year-old female underwent an electrophysiology ablation procedure for 1917

posterior pathway pre-excitation that lasted 5 hours. Eleven months later she underwent 1918

a second procedure that also lasted 5 hours. Both procedures were performed with 1919

biplane fluoroscopy. Fluoroscopy time for the lateral plane was estimated at 90-120 1920

minutes. Skin dose estimates are not available. Twelve hours after the second procedure 1921

she developed an erythematous plaque in the right axilla. One month later she consulted 1922

a dermatologist for red macular and blister lesions on her right side. Twenty-six months 1923

after the second procedure an indurated, atrophic plaque with linear edges, 10 x 5 cm2, 1924

was observed (Fig. 3.5). The diagnosis was chronic radiodermatitis. The muscles in her 1925

right arm have also been affected, with resultant limitation in the range of motion. 1926

Because of the patient‘s age and the region irradiated, her risk of subsequent breast 1927

cancer is also increased. 1928

1929

1930

1931 1932

Figure 3.5 Case 5. Indurated, atrophic plaque with linear edges, with areas of hyper- and 1933

hypopigmentation. Reprinted from Vañó, 1998. (Permission needed) 1934

1935

1936


48

3.7 Case 6 (Courtesy of Dr. M. Portas, Buenos Aires, Argentina) 1937

1938 (66) An obese 57-year-old female, a heavy smoker, underwent PTCA. The 1939

procedure time was approximately 6 hours. No data on radiation dose are available. 1940

Early manifestations were blisters on the skin of the back in the lumbar region. This was 1941

diagnosed by a dermatologist as a herpes zoster infection. Two months later, a deep ulcer 1942

(Radiation Therapy Oncology Group/European Organisation for Research and Treatment 1943

of Cancer [RTOG/EORTC] cutaneous radiotoxicity grade 4) appeared at the same site. 1944

(No photographs of the injury at this stage are available.) It was extremely painful. The 1945

following year the patient underwent a plastic surgery procedure, with two rotation flaps 1946

to close the wound. The rotation flaps subsequently underwent necrosis, leaving an ulcer 1947

approximately 20 x 20 cm (Fig. 3.6). During the next several years, conservative 1948

treatment was performed at a specialized burn centre. Wound coverage was performed 1949

with porcine dermis, skin allografts and autografts, in conjunction with anti-inflammatory 1950

and antibacterial therapy and hyperbaric oxygen treatments. This treatment led to 1951

progressive wound closure. After 3 years of treatment (5 years after the PTCA), the 1952

dimensions of the ulcer were reduced to 3 x 1.5 cm (Fig 3.7). In vitro radiosensitivity 1953

testing demonstrated that the patient had normal radiosensitivity. The injury and 1954

prolonged recovery were attributed to radiation exposure, obesity and heavy smoking. 1955

1956

1957

1958 1959

1960

Figure 3.6 Case 6. Appearance of the patient‘s back following the initial surgery and 1961

necrosis of the rotation flaps. The ulcer is approximately 20 x 20 cm. 1962

1963


49

1964

1965 1966

Figure 3.7 Case 6. Appearance of the patient‘s back 5 years after the PTCA. After 3 1967

years of treatment, the ulcer is reduced in size to 3 x 1.5 cm. The patient‘s quality of life 1968

is much improved. 1969

1970

1971


Bryk, S.G., Censullo, M.L., Wagner, L.K., Rossman, L.L., Cohen, A.M., 2006. 1974

Endovascular and interventional procedures in obese patients: a review of procedural 1975

technique modifications and radiation management. J. Vasc. Interv. Radiol. 17, 27-1976

33. 1977

Koenig, T.R., Wolff, D., Mettler, F.A., Wagner, L.K., 2001. Skin injuries from 1978

fluoroscopically guided procedures: Part 1, Characteristics of radiation injury. AJR. 1979

Am. J. Roentgenol. 177, 3-11. 1980

Suzuki, S., Furui, S., Isshiki, T., Kozuma, K., Koyama, Y., Yamamoto, H., Ochiai, M., 1981

Asakura, Y., Ikari, Y., 2008. Patients' skin dose during percutaneous coronary 1982

intervention for chronic total occlusion. Catheter. Cardiovasc. Interv. 71, 160-164. 1983

UNSCEAR. Sources of ionizing radiation: volume I. Report to the General Assembly, 1984

with scientific annexes; 2010; New York, NY. Available at: 1985

http://www.unscear.org/unscear/en/publications/2008_1.html Accessed December 1986

31, 2010. 1987



50

Vañó, E., Arranz, L., Sastre, J.M., Moro, C., Ledo, A., Gárate, M.T., Minguez, I., 1998. 1988

Dosimetric and radiation protection considerations based on some cases of patient 1989

skin injuries in interventional cardiology. Br. J. Radiol. 71, 510-516. 1990

Vlietstra, R.E., Wagner, L.K., Koenig, T., Mettler, F., 2004. Radiation burns as a severe 1991

complication of fluoroscopically guided cardiological interventions. J Interv Cardiol 1992

17, 1-12. 1993

1994

1995

1996


51

1997

4. PRINCIPLES OF RADIOLOGICAL PROTECTION FOR 1998

PATIENTS AND STAFF 1999

2000

Main Points 2001

2002

Justification means that a medical procedure should only be performed when it 2003

is appropriate for a particular patient— the anticipated clinical benefits should 2004

exceed all anticipated procedural risks, including radiation risk. 2005

For CT and nuclear medicine studies, justification is a responsibility shared 2006

between the referring clinician and the cardiac imager. For fluoroscopically 2007

guided interventions, the responsibility rests with the interventionalist. 2008

Optimization means that the radiation dose to the patient is suitable for the 2009

medical purpose, and radiation that is clinically unnecessary or unproductive is 2010

avoided. 2011

Patient radiation dose is optimized when imaging is performed with the least 2012

amount of radiation required to provide adequate image quality, diagnostic 2013

information, and for fluoroscopy, adequate imaging guidance. 2014

Dose limits apply to occupational exposure of cardiologists and staff. 2015

Dose limits do not apply to medical exposures of patients or to carers and 2016

comforters. 2017 2018


(67) The Commission recommends three fundamental principles of radiological 2020

protection: justification, optimization of protection, and application of dose limits (ICRP 2021

103, ICRP 105). The first two are source related and apply to all radiation exposure 2022

situations. The third applies to staff, but does not apply to medical exposures of patients 2023

or to carers and comforters. 2024

4.2 Justification 2025

(68) The principle of justification is that, in general, ―any decision that alters the 2026

radiation exposure situation should do more good than harm. This means that by 2027

introducing a new radiation source, by reducing existing exposure, or by reducing the risk 2028

of potential exposure, one should achieve sufficient individual or societal benefit to offset 2029

the detriment it causes.‖ (ICRP 103, ICRP 105). The principal aim of medical exposures 2030

is to do more good than harm to the patient, subsidiary account being taken of the 2031

radiation detriment from the exposure of the radiological staff and of other individuals 2032

(ICRP 103). 2033

(69) A medical procedure should only be performed when it is appropriate for a 2034

particular patient. The RAND Corporation has developed a definition of ―appropriate‖ 2035

that is widely used: the expected health benefit (i.e., increased life expectancy, relief of 2036

pain, reduction in anxiety, improved functional capacity) exceeds the expected negative 2037

consequences (i.e., mortality, morbidity, anxiety of anticipating the procedure, pain 2038

produced by the procedure, misleading or false diagnoses, time lost from work) by a 2039


52

sufficiently wide margin that the procedure is worth doing (Sistrom, 2008, NHS, 1993). 2040

In other words, the anticipated clinical benefits should exceed all anticipated procedural 2041

risks, including radiation risk. 2042

(70) In the United States, appropriateness criteria have been developed for many 2043

clinical scenarios (Brindis et al, 2005, Douglas, 2008, Patel, 2009, Hendel 2009, ACR, 2044

2010, Taylor 2010). Similar guidelines have been developed in the United Kingdom, 2045

though they are less readily available (RCR, 2007). European guidelines are also 2046

available (Hesse, 2005, Schroeder 2008). These recommendations are typically based on 2047

a standardized literature review and compilation of evidence tables, followed by rating of 2048

each indication by an expert panel with varied composition (Patel et al, 2005). 2049

Appropriateness may vary based on national and local norms and practice patterns, as 2050

well as well as patient and family values and preferences (Wolk et al, 2004). 2051

(71) The responsibility for the justification of the use of a particular procedure falls 2052

on the relevant medical practitioners (ICRP 103). For CT and nuclear medicine studies, 2053

justification is a responsibility shared between the referring clinician and the cardiac 2054

imager. For the referring clinician, this entails weighing the benefits of a test against its 2055

risks, including radiation exposure, and considering such an analysis for all possible 2056

alternatives including performing no test. For the cardiac imager, justification entails 2057

ensuring that the test has a reasonable indication, given the available information, and 2058

discussing the indication with the referring clinician if there is concern in this respect. 2059

For fluoroscopically guided interventions, the responsibility rests with the 2060

interventionalist. 2061

2062

4.3 Optimization 2063

(72) The principle of optimization of protection is that ―the likelihood of incurring 2064

exposures, the number of people exposed, and the magnitude of their individual doses 2065

should all be kept as low as reasonably achievable, taking into account economic and 2066

societal factors. This means that the level of protection should be the best under the 2067

prevailing circumstances, maximizing the margin of benefit over harm‖ (ICRP 103, ICRP 2068

105, NCRP 1993). This is often summarized using the acronym ALARA, which stands 2069

for As Low As Reasonably Achievable. 2070

(73) For cardiology procedures, this principle is applied in the design of cardiac 2071

facilities that use ionizing radiation, appropriate selection and use of equipment, and in 2072

day-to-day working procedures. Optimization is best described as a radiation dose to the 2073

patient that is suitable for the medical purpose, and avoidance of radiation that is 2074

clinically unnecessary or unproductive. 2075

(74) Dose optimization means delivering a radiation dose to the organs and tissues 2076

of clinical interest no greater than that required for adequate imaging and minimizing 2077

dose to other structures (e.g., the skin). Patient radiation dose is considered to be 2078

optimized when imaging is performed with the least amount of radiation required to 2079

provide adequate image quality and, for fluoroscopy, adequate imaging guidance (NCI, 2080

2005). The goal of every imaging procedure is to provide images adequate for the 2081

clinical purpose. Imaging requirements depend on the specific patient and the specific 2082

procedure. Reducing patient radiation dose to the point where images are inadequate is 2083


53

counterproductive; it results in radiation dose to the patient without answering the clinical 2084

question. Improving image quality beyond what is clinically needed subjects the patient 2085

to additional radiation dose without additional clinical benefit. The goal of radiation 2086

management is to keep patient radiation dose as low as possible consistent with the use of 2087

appropriate equipment and the imaging requirements for a specific patient and a specific 2088

procedure. 2089

4.4 Dose limits 2090

(75) The principle of application of dose limits states that ―the total dose to any 2091

individual from regulated sources in planned exposure situations other than medical 2092

exposure of patients should not exceed the appropriate limits recommended by the 2093

Commission‖ (ICRP 103, ICRP 105). This principle does not apply to medical exposure 2094

of patients. As noted in ICRP Publication 105, ―Provided that the medical exposures of 2095

patients have been properly justified and that the associated doses are commensurate with 2096

the medical purpose, it is not appropriate to apply dose limits or dose constraints to the 2097

medical exposure of patients, because such limits or constraints would often do more 2098

harm than good.‖(ICRP 105) For interventional procedures, the medical condition being 2099

treated and the non-radiation risks of the procedure typically present substantially greater 2100

morbidity and mortality than do the radiation risks (Miller, 2008, NCRP 168, 2010). 2101

2102


What do we mean by appropriate health care? Report of a working group prepared for 2105

the Director of Research and Development of the NHS Management Executive. Qual 2106

Health Care 1993;2:117-23. 2107

American College of Radiology. ACR Appropriateness Criteria®. Available at: 2108

http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx 2109

Accessed August 3, 2010. 2110

Brindis RG, Douglas PS, Hendel RC, Peterson ED, Wolk MJ, Allen JM, Patel MR, 2111

Raskin IE, Bateman TM, Cerqueira MD, Gibbons RJ, Gillam LD, Gillespie JA, 2112

Iskandrian AE, Jerome SD, Krumholz HM, Messer JV, Spertus JA, Stowers SA. 2113

ACCF/ASNC appropriateness criteria for single-photon emission computed 2114

tomography myocardial perfusion imaging (SPECT MPI): a report of the American 2115

College of Cardiology Foundation Quality Strategic Directions Committee 2116

Appropriateness Criteria Working Group and the American Society of Nuclear 2117

Cardiology endorsed by the American Heart Association. J Am Coll Cardiol 2118

2005;46:1587-1605. 2119

Douglas, P.S., Khandheria, B., Stainback, R.F., Weissman, N.J., Peterson, E.D., Hendel, 2120

R.C., Blaivas, M., Des Prez, R.D., Gillam, L.D., Golash, T., Hiratzka, L.F., 2121

Kussmaul, W.G., Labovitz, A.J., Lindenfeld, J., Masoudi, F.A., Mayo, P.H., 2122

Porembka, D., Spertus, J.A., Wann, L.S., Wiegers, S.E., Brindis, R.G., Patel, M.R., 2123

Wolk, M.J., Allen, J.M., 2008. ACCF/ASE/ACEP/AHA/ASNC/SCAI/SCCT/SCMR 2124

2008 appropriateness criteria for stress echocardiography: a report of the American 2125

College of Cardiology Foundation Appropriateness Criteria Task Force, American 2126

Society of Echocardiography, American College of Emergency Physicians, 2127

http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx


54

American Heart Association, American Society of Nuclear Cardiology, Society for 2128

Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed 2129

Tomography, and Society for Cardiovascular Magnetic Resonance endorsed by the 2130

Heart Rhythm Society and the Society of Critical Care Medicine. J. Am. Coll. 2131

Cardiol. 51, 1127-1147. Available at: 2132

http://content.onlinejacc.org/cgi/content/full/51/11/1127 Accessed January 1, 2011. 2133

Hendel RC, Berman DS, Di Carli MF, et al. 2134

ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 appropriate use criteria for 2135

cardiac radionuclide imaging: a report of the American College of Cardiology 2136

Foundation Appropriate Use Criteria Task Force, the American Society of Nuclear 2137

Cardiology, the American College of Radiology, the American Heart Association, 2138

the American Society of Echocardiography, the Society of Cardiovascular Computed 2139

Tomography, the Society for Cardiovascular Magnetic Resonance, and the Society of 2140

Nuclear Medicine. Circulation. 2009;119(22):e561-587. 2141

Hesse, B., Tagil, K., Cuocolo, A., Anagnostopoulos, C., Bardies, M., Bax, J., Bengel, F., 2142

Busemann Sokole, E., Davies, G., Dondi, M., Edenbrandt, L., Franken, P., Kjaer, A., 2143

Knuuti, J., Lassmann, M., Ljungberg, M., Marcassa, C., Marie, P.Y., McKiddie, F., 2144

O'Connor, M., Prvulovich, E., Underwood, R., van Eck-Smit, B., 2005. EANM/ESC 2145

procedural guidelines for myocardial perfusion imaging in nuclear cardiology. Eur J 2146

Nucl Med Mol Imaging 32, 855-897. Available at: 2147

http://www.eanm.org/scientific_info/guidelines/gl_cardio_myocard_perf.pdf 2148

Accessed January 1, 2011. 2149

International Commission on Radiological Protection. The 2007 Recommendations of 2150

the International Commission on Radiological Protection. ICRP Publication 103. 2151

Ann ICRP 2007; 37(2-4):1-332 2152

International Commission on Radiological Protection. Radiological protection in 2153

medicine. ICRP Publication 105. Ann ICRP 2007;37:1-63. 2154

Miller DL. Overview of contemporary interventional fluoroscopy procedures. Health 2155

Phys 2008; 95:638-644. 2156

NCI. Interventional fluoroscopy: reducing radiation risks for patients and staff. NIH 2157

Publication No. 05-5286. Bethesda:National Cancer Institute, 2005. Available at: 2158

http://www.cancer.gov/images/Documents/45bae965-697a-4de8-9dae-2159

b77222e0e79d/InterventionalFluor.pdf Accessed January 1, 2011. 2160

NCRP. Limitation of exposure to ionizing radiation. NCRP Report No. 116. Bethesda, 2161

MD: National Council on Radiation Protection and Measurements; 1993. 2162

NCRP. Radiation dose management for fluoroscopically guided interventional medical 2163

procedures. NCRP Report No. 168. Bethesda, MD: National Council on Radiation 2164


Patel MR, Spertus JA, Brindis RG, Hendel RC, Douglas PS, Peterson ED, Wolk MJ, 2166

Allen JM, Raskin IE. ACCF proposed method for evaluating the appropriateness of 2167

cardiovascular imaging. J Am Coll Cardiol 2005;46:1606-1613. 2168

Patel, M.R., Dehmer, G.J., Hirshfeld, J.W., Smith, P.K., Spertus, J.A., 2009. 2169

ACCF/SCAI/STS/AATS/AHA/ASNC 2009 Appropriateness Criteria for Coronary 2170

Revascularization: a report by the American College of Cardiology Foundation 2171

http://content.onlinejacc.org/cgi/content/full/51/11/1127

http://www.eanm.org/scientific_info/guidelines/gl_cardio_myocard_perf.pdf




55

Appropriateness Criteria Task Force, Society for Cardiovascular Angiography and 2172

Interventions, Society of Thoracic Surgeons, American Association for Thoracic 2173

Surgery, American Heart Association, and the American Society of Nuclear 2174

Cardiology Endorsed by the American Society of Echocardiography, the Heart 2175

Failure Society of America, and the Society of Cardiovascular Computed 2176

Tomography. J. Am. Coll. Cardiol. 53, 530-553. Available at: 2177

http://content.onlinejacc.org/cgi/content/full/53/6/530 Accessed January 1, 2011. 2178

The Royal College of Radiologists. Making the best use of clinical radiology services: 2179

referral guidelines. 6th

ed. London:The Royal College of Radiologists, 2007. 2180

Schroeder S, Achenbach S, Bengel F, et al. Cardiac computed tomography: indications, 2181

applications, limitations, and training requirements: report of a Writing Group 2182

deployed by the Working Group Nuclear Cardiology and Cardiac CT of the 2183

European Society of Cardiology and the European Council of Nuclear Cardiology. 2184

Eur Heart J 2008;29(4):531-556. 2185

Sistrom CL. In support of the ACR Appropriateness Criteria®. J Am Coll Radiol 2186

2008;5:630-635. 2187

Taylor, A.J., Cerqueira, M., Hodgson, J.M., Mark, D., Min, J., O'Gara, P., Rubin, G.D., 2188

Kramer, C.M., Berman, D., Brown, A., Chaudhry, F.A., Cury, R.C., Desai, M.Y., 2189

Einstein, A.J., Gomes, A.S., Harrington, R., Hoffmann, U., Khare, R., Lesser, J., 2190

McGann, C., Rosenberg, A., Schwartz, R., Shelton, M., Smetana, G.W., Smith, S.C., 2191

Jr., 2010. ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 2192

appropriate use criteria for cardiac computed tomography: a report of the American 2193

College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society 2194

of Cardiovascular Computed Tomography, the American College of Radiology, the 2195

American Heart Association, the American Society of Echocardiography, the 2196

American Society of Nuclear Cardiology, the North American Society for 2197

Cardiovascular Imaging, the Society for Cardiovascular Angiography and 2198

Interventions, and the Society for Cardiovascular Magnetic Resonance. J. Am. Coll. 2199

Cardiol. 56, 1864-1894. Available at: 2200

http://content.onlinejacc.org/cgi/content/full/56/22/1864 Accessed January 1, 2011.in 2201

press. 2202

Wolk MJ, Peterson E, Brindis R, Eagle K. President's page: the appropriate cardiologist: 2203

responsible stewardship in a golden era of cardiology. J Am Coll Cardiol 2204

2004;44:933-935. 2205

2206




56

5. MANAGING PATIENT DOSE IN FLUOROSCOPICALLY 2207

GUIDED INTERVENTIONS 2208

2209

Main Points 2210

2211

The informed consent process should include information on radiation risk if 2212

the risk of radiation injury is thought to be significant. 2213

Important aspects of the patient’s medical history that should be considered 2214

when estimating radiation risk are genetic factors, co-existing diseases, 2215

medication use, radiation history, and pregnancy. 2216

Some of the factors that affect the patient’s radiation dose depend on the x-ray 2217

system, but many others depend on how the operator uses the x-ray system. 2218

During the procedure, the cardiologist should be kept aware of the fluoroscopy 2219

time, the number of cine series and cine frames, and the total patient dose. 2220

As patient radiation dose increases, the operator should consider the radiation 2221

dose already delivered to the patient and the additional radiation necessary to 2222

complete the procedure. 2223

Patient radiation dose reports should be produced at the end of the procedure, 2224

and archived. 2225

Radiation dose data should be recorded in the patient’s medical record after the 2226

procedure. 2227

When the patient’s radiation dose from the procedure is high, clinical follow-up 2228

is essential for early detection and management of skin injuries. 2229

Patients who have received a substantial radiation dose should have follow-up 2230

at 10-14 days and at one month after the procedure for possible deterministic 2231

effects. 2232 2233


(76) Fluoroscopically guided interventions (FGI) comprise guided therapeutic and 2236

diagnostic interventions, by percutaneous or other access, usually performed under local 2237

anaesthesia and/or sedation, with fluoroscopic imaging used to localise the 2238

lesion/treatment site, monitor the procedure, and control and document the therapy 2239

(ICRP, 2000). This chapter deals with clinical radiation management before, during and 2240

after FGI. 2241

(77) The doses received by patients during fluoroscopically guided cardiac 2242

procedures can be high, and some patients may have several procedures carried out in a 2243

relatively short period of time. Hence, it is essential that the cardiologist optimises 2244

patient radiation dose (Chambers, 2011). If a certain dose threshold is exceeded (see 2245

Chapter 2), the procedure could result in deterministic effects (harmful tissue reactions). 2246

High radiation doses also increase stochastic risk (cancer and heritable effects). 2247

2248


57

It is important for medical practitioners to be aware that although uncertainty remains, the 2249

absorbed dose threshold for circulatory disease may be as low as 0.5 Gy to the heart and 2250

brain (ICRP, 2011a). In some complex fluoroscopically guided cardiac procedures, 2251

organ doses may be > 0.5 Gy. Cardiovascular radiation effects have been reported to 2252

occur at these doses, including focal myocardial degeneration and fibrosis, and 2253

accelerated atherosclerosis in major blood vessels. (ICRP XXX Tissue Reactions, 2254

2011b). 2255

(78) The mean age of patients undergoing cardiac procedures is relatively high. 2256

Stochastic risk is not a great concern for older patients because of the latency period for 2257

the development of cancer and these patients‘ relatively shorter life expectancies. 2258

Stochastic risk is of greater concern when fluoroscopically guided procedures are 2259

performed on children. Children have longer life expectancies and are also more 2260

sensitive to the effects of radiation. 2261

(79) Initial and continuous training in dose management and radiological protection 2262

has a definitive influence on patient doses, and is essential for interventionalists 2263

(Hirshfeld, 2005, Rehani, 2007, ICRP 2009). Several recent publications have 2264

demonstrated that this training helps to optimise patient dose and reduce operator dose 2265

(Whitby, 2005, Vano, 2006, Bor, 2008, Bernardi, 2008, Kim, 2010, IAEA TECDOC 2266

1641, 2010). Training is discussed further in Chapter 9. 2267

2268

5.2 Before the Procedure 2269 2270

(80) A discussion of radiation risk is an appropriate part of the informed consent 2271

process if radiation risk factors are present or a substantial radiation dose is anticipated. 2272

ICRP recommends that patients should be counselled before the procedure if the risk of 2273

radiation injury is thought to be significant (ICRP Publication 85). Important aspects of 2274

the patient‘s medical history that should be considered when estimating radiation risk are 2275

genetic factors, co-existing diseases, medication use, radiation history, and pregnancy 2276

(Miller et al, 2010). 2277

(81) Obese patients are at a higher risk of radiation-induced skin injury because of 2278

poor radiation penetration and the accompanying closer proximity of the x-ray source to 2279

the patient (Bryk, 2006). Absorbed dose at the entrance skin site in obese patients can be 2280

as much as 10 times higher than in non-obese patients (Wagner, JVIR 2000). Many of the 2281

documented injuries associated with fluoroscopic procedures have been seen in larger 2282

patients (Koenig Part 2, 2001). 2283

(82) For some complex procedures, and especially when procedures are repeated in 2284

large or obese patients, a medical physicist can provide useful advice to help optimise the 2285

procedure. If a previous procedure has resulted in a high peak skin dose, the strategy for 2286

further possible procedures in the same patient should include modifying subsequent 2287

procedures to reduce skin dose, if possible. Other procedure modifications are often 2288

necessary in obese patients (Bryk, 2006). 2289

(83) Except for time-critical emergency procedures, pregnancy status should be 2290

determined prior to a fluoroscopically guided intervention (ICRP 105). If possible, 2291

elective procedures on pregnant patients should be deferred until the patient is no longer 2292


58

pregnant. When medically indicated FGI procedures must be performed on pregnant 2293

patients, and except for time-critical emergency procedures, the Commission 2294

recommends that procedure planning include feasible modifications to minimize 2295

conceptus dose, estimation of expected radiation dose to the conceptus, evaluation of the 2296

radiogenic risk to the conceptus, and inclusion in the informed consent process of the 2297

expected benefits and potential risks of the procedure to both the patient and the 2298

conceptus (ICRP 84). Whenever possible, and if time permits, the pre-procedure 2299

planning process should involve a qualified physicist. 2300

(84) The Commission has stated that in general, termination of pregnancy at foetal 2301

doses of less than 100 mGy is not justified based upon radiation risk (ICRP Publication 2302

84). For comparison, a typical fetal dose from CTA of the coronary arteries is 2303

approximately 0.1 mGy (McCollough, 2007). 2304

2305

5.3 During the Procedure 2306 2307

(85) When optimizing patient radiation dose, the first priority must be to obtain a 2308

sufficient number of images of a high enough quality to permit diagnosis and guide 2309

interventions. This will require a certain minimum amount of fluoroscopy time and 2310

number and length of cine series. Optimal management of patient dose requires 2311

knowledge and control of the typical fluoroscopic dose rates and values of dose per cine 2312

frame for the most common operational modes. 2313

(86) Typical values of skin dose rate (surface entrance air kerma rate) during 2314

cardiology procedures for a medium size patient are 15-45 mGy/min for ―medium‖ 2315

fluoroscopy mode and 50-150 mGy/min for ―high‖ fluoroscopy mode. Skin dose per cine 2316

frame is typically between 0.1 and 1.0 mGy. Skin doses in cardiac procedures can reach 2317

several Gy, especially for complex procedures and when several projections with similar 2318

C-arm angulations are required (Miller, 2008). Organ doses may reach 100 Gy and 2319

effective doses may reach 50 mSv. Variation in patient doses between centres may be 2320

substantial. Some of this variation is likely to be due to the settings of the x-ray systems. 2321

A study carried out by the IAEA comparing x-ray systems from different countries 2322

demonstrated 10-fold differences for dose values when phantoms of the same thickness 2323

were imaged (Ortiz at al, 2004). 2324

(87) Several operational factors can substantially modify the radiation dose received 2325

by the patients and affect the kerma-area product (KAP) and the patient‘s skin dose 2326

(Publication 85). These are also discussed and illustrated in an ICRP publication devoted 2327

to radiological protection outside the imaging department (reference ICRP TG 78). Some 2328

of these factors depend on the x-ray system (e.g. availability of pulsed fluoroscopy, 2329

virtual collimation, stored fluoroscopy loops, extra filtration, wedge filters, rotational and 2330

cone beam CT acquisition modes, etc.), but others depend on how the operator uses the x-2331

ray system (e.g. collimation to the area of interest, use of low fluoroscopy modes when 2332

possible, acquiring cine series at 12.5-15 frames per second when possible, keeping the 2333

image detector as close as possible to the patient, avoiding steeply angulated projections, 2334

reducing the number of frames per cine series) (NCRP Report 168, 2010). 2335

Recommendations for dose optimization in the radiology literature apply equally to 2336


59

interventional cardiology procedures (Miller, 2002, Miller, 2010, Wagner, JVIR 2000, 2337

Wagner 2007). Table 5.1 provides some practical advice. 2338

(88) During the procedure, the cardiologist should be aware of the fluoroscopy time, 2339

the number of cine series and cine frames, and the total patient dose, either as KAP or as 2340

Reference Air Kerma (RAK) the cumulative air kerma at the Interventional Reference 2341

Point (see Glossary). (The Interventional Reference Point is also known as the Patient 2342

Entrance Reference Point.) The need here is to monitor, in real time, whether the 2343

threshold doses for deterministic effects are being approached or exceeded (ICRP 105, 2344

ICRP XXX 2011b). Modern fluoroscopy systems that are compliant with the 2345

international standard for interventional fluoroscopy systems display radiation data to the 2346

operator during the procedure (IEC, 2010). The responsibility for monitoring radiation 2347

dose may be delegated to a technologist, nurse or other person depending on national or 2348

local regulations and the institution‘s policy and needs (NCRP 168, 2010). A specific 2349

individual should be tasked with this responsibility. The purpose of dose monitoring is to 2350

ensure that the operator is aware of how much radiation is being administered. 2351

(89) As patient radiation dose increases, the operator should consider the radiation 2352

dose already delivered to the patient and the additional radiation necessary to complete 2353

the procedure. It may be possible to reduce further radiation usage and control skin dose 2354

by limiting the number and length of cine series, decreasing the dose rate for cine or 2355

fluoroscopy, using collimation or changing the gantry angle slightly. 2356

(90) Knowledge of the patient‘s skin dose distribution could help to avoid the risk 2357

of skin injuries, but measurement of skin dose distribution is not an easy task in 2358

fluoroscopically guided procedures. This is especially true in cardiology, where very 2359

different C-arm angulations are used during the procedures and the regions of the 2360

irradiated skin can also be very different. However, using different C-arm angulations 2361

can help reduce peak skin dose, especially when collimation is also used (Miller, 2002). 2362

Figure 5.1 shows an example of skin dose distribution measured with slow film (Vano et 2363

al. 1997) and how overlap of radiation fields can increase the dose to a certain area of the 2364

skin. 2365

2366

5.4 After the procedure 2367 2368

(91) Modern fluoroscopy systems that are compliant with the international standard 2369

for interventional fluoroscopy systems provide a dose report at the conclusion of the 2370

procedure (IEC, 2010). An example of a typical dose report is shown in Fig 5.2. Several 2371

companies offer dose reports for cardiology procedures that include information on skin 2372

dose distribution. Patient radiation dose reports should be produced at the end of the 2373

procedure, and archived. Radiation dose data should be recorded in the patient‘s medical 2374

record after the procedure (Chambers, 2011). 2375

(92) Patient doses for cardiac procedures are often reported as kerma-area product 2376

(KAP). Skin dose distribution, and especially RAK and peak skin dose (PSD) (defined in 2377

the glossary), are sometimes more important, particularly when repeated procedures are 2378

performed on the same patient (Miller, 2002). Fluoroscopy time does not include the 2379

effect of fluoroscopy dose rate and does not indicate the radiation dose from cine. It is 2380


60

not a useful descriptor of patient radiation dose (Chida, 2006, Fletcher, 2002). 2381

Fluoroscopy time should not be the only dose measurement recorded or audited 2382

(Chambers, 2011, NCRP Report 168, 2010). 2383

(93) The management and follow-up of patients who have received a high dose of 2384

radiation is also important. The operator should be notified promptly if the substantial 2385

radiation dose level (SRDL) was exceeded. (SRDL is defined in the Glossary and 2386

discussed further in Section 10.6.) The operator should write an appropriate note in the 2387

patient‘s medical record, stating that a substantial radiation dose has been administered, 2388

and indicating the reason (Hirshfeld, 2005). This information may be included in the 2389

post-procedure note. 2390

(94) When the SRDL has been exceeded, clinical follow-up is essential for early 2391

detection and management of skin injuries (NCRP Report 168, 2010, Chambers, 2011). 2392

The patient should be advised of the possibility of a deterministic skin injury, and should 2393

be told to examine the beam entrance site at 2 – 4 weeks after the procedure. The 2394

operator should be notified if any skin changes are seen. Patients should also be 2395

contacted by telephone at approximately 30 days after the procedure. If a skin injury is 2396

suspected, the interventionalist should see the patient at an office visit, and should 2397

arrange for appropriate follow-up care (NCRP Report 168, 2010, Chambers, 2011). The 2398

physician responsible for the patient‘s care should be informed of the possibility of 2399

radiation effects. Ideally, a system should be established to identify and monitor repeated 2400

procedures (ICRP 85, 2000). 2401

2402

5.5 Paediatric Patients 2403 2404

(95) Paediatric cardiology procedures require special consideration. These 2405

interventions are often challenging, time-consuming and may require multi-stage 2406

procedures, leading to high radiation exposure. Contributing factors include the higher 2407

heart rates, smaller cardiovascular structures, small body size and wider variety of 2408

unusual anatomic variants seen in children (Justino 2006). 2409

(96) Patient radiation dose from paediatric interventional cardiology procedures can 2410

be reduced by the use of dedicated radiographic protocols that include tighter collimation, 2411

pulsed fluoroscopy frame rates of 25-30 frames/sec and cine frame rates of 25-50 2412

frames/sec. As part of the Step Lightly initiative, the Alliance for Radiation Safety in 2413

Pediatric Imaging has published a checklist for use during paediatric interventional 2414

fluoroscopy to help reduce patient doses (Sidhu, 2009). 2415

2416


American College of Radiology. ACR practice guideline for imaging pregnant or 2419

potentially pregnant adolescents and women with ionizing radiation. Practice 2420

Guidelines and Technical Standards 2008. Reston, VA: American College of 2421

Radiology, 2008; p. 23-37. Available at: 2422

http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/dx/Pre2423

gnancy.aspx Accessed August 11, 2010. 2424

http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/dx/Pregnancy.aspx

http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/dx/Pregnancy.aspx


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Balter S. Interventional fluoroscopy. Physics, technology and safety. Wiley-Liss, New 2425

York, 2001. 2426

Bernardi G, Padovani R, Morocutti G, Vano E, Malisan MR, Rinuncini M, Spedicato L, 2427

Fioretti PM. Clinical and technical determinants of the complexity of percutaneous 2428

transluminal coronary angioplasty procedures: analysis in relation to radiation 2429

exposure parameters. Catheter Cardiovasc Interv 2000 Sep;51(1):1-9; discussion 10. 2430

Bernardi G, Padovani R, Trianni A, Morocutti G, Spedicato L, Zanuttini D, Werren M, 2431

Wagner LK. The effect of fellows‘ training in invasive cardiology on radiological 2432

exposure of patients. Radiat Prot Dosimetry 2008, 128(1):72–76. 2433

Bor D, Sancak T, Toklu T, Olgar T, Ener S. Effects of radiologists' skill and experience 2434

on patient doses in interventional examinations. Radiat Prot Dosimetry 2008;129:32-2435

5. 2436

Bryk SG, Censullo ML, Wagner LK, Rossman LL, Cohen AM. Endovascular and 2437

interventional procedures in obese patients: a review of procedural technique 2438

modifications and radiation management. J Vasc Interv Radiol 2006;17:27-33. 2439

Chambers CE, Fetterly KA, Holzer R, Lin P-JP, Blankenship JC, Balter S, Laskey WK. 2440

Radiation safety program for the cardiac catheterization laboratory. Catheter 2441

Cardiovasc Interv 2011, in press. 2442

Chida K, Saito H, Otani H, Kohzuki M, Takahashi S, Yamada S, Shirato K, Zuguchi M. 2443

Relationship between fluoroscopic time, dose-area product, body weight, and 2444

maximum radiation skin dose in cardiac interventional procedures. Am J Roentgenol. 2445

2006;186:774-8. 2446

Den Boer A, de Feyter PJ, Hummel WA, Keane D, Roelandt JR. Reduction of radiation 2447

exposure while maintaining high-quality fluoroscopic images during interventional 2448

cardiology using novel x-ray tube technology with extra beam filtering. Circulation. 2449

1994 Jun;89(6):2710-4. 2450

Faulkner K, Vano E. Deterministic effects in interventional radiology. Radiat Prot 2451

Dosimetry. 2001;94(1-2):95-8. 2452

Fletcher DW, Miller Dl, Balter S, Taylor MA. Comparison of four techniques to 2453

estimate radiation dose to skin during angiographic and interventional radiology 2454

procedures. J Vasc Interv Radiol 2002;13:391-97. 2455

Guibelalde E, Vano E, Gonzalez L, Prieto C, Fernandez JM, Ten JI. Practical aspects for 2456

the evaluation of skin doses in interventional cardiology using a new slow film. Br J 2457

Radiol. 2003 May;76(905):332-6. 2458

Hirshfeld JW Jr, Balter S, Brinker JA, Kern MJ, Klein LW, Lindsay BD, Tommaso CL, 2459

Tracy CM, Wagner LK, Creager MA, Elnicki M, Lorell BH, Rodgers GP, Weitz 2460

HH; American College of Cardiology Foundation; American Heart Association; 2461

HRS; SCAI; American College of Physicians Task Force on Clinical Competence 2462

and Training. ACCF/AHA/HRS/SCAI clinical competence statement on physician 2463

knowledge to optimize patient safety and image quality in fluoroscopically guided 2464

invasive cardiovascular procedures: a report of the American College of Cardiology 2465

Foundation/American Heart Association/American College of Physicians Task Force 2466

on Clinical Competence and Training. Circulation. 2005;111(4):511-32. 2467


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IAEA, 2010. Patient dose optimization in fluoroscopically guided interventional 2468

procedures. IAEA-TECDOC-1641. Vienna: International Atomic Energy Agency, 2469

2010. 2470

International Commission on Radiological Protection. Radiological protection and safety 2471

in medicine. ICRP Publication 73. Ann ICRP 1996; 26(2):1-47 2472

International Commission on Radiological Protection. Pregnancy and medical radiation. 2473

ICRP Publication 84. Ann ICRP 2000; 30:1-43. 2474

International Commission on Radiological Protection. Avoidance of radiation injuries 2475

from medical interventional procedures. ICRP Publication 85. Ann ICRP 2000; 2476

30(2):1-67. 2477

International Commission on Radiological Protection. The 2007 Recommendations of 2478

the International Commission on Radiological Protection. ICRP publication 103. 2479

Ann ICRP 2007;37:1-332. 2480

International Commission on Radiological Protection. Radiological protection in 2481

medicine. ICRP Publication 105. Ann ICRP 2007; 37:1-63. 2482


Protection. ICRP Publication 113, Ann. ICRP 39 (5). 2484

International Commission on Radiological Protection 2011a. Statement on Tissue 2485

reactions. Approved by the Commission on April 21, 2011. ICRP ref 4825-3093-2486

1464. Available at 2487

http://www.icrp.org/docs/ICRP%20Statement%20on%20Tissue%20Reactions.pdf 2488

Accessed May 9, 2011. 2489

International Commission on Radiological Protection 2011b. Tissue Reactions and Other 2490

Non-Cancer Effects of Radiation. ICRP Publication XXX. Ann ICRP 2011; in press 2491

IEC. Medical electrical equipment. Part 2-43: Particular requirements for the safety of 2492

X-ray equipment for interventional procedures. IEC 60601-2-43. 2nd edition, 2493

Geneva, Switzerland: International Electrotechnical Commission; 2010. 2494

Justino H. The ALARA concept in pediatric cardiac catheterization: techniques and 2495

tactics for managing radiation dose. Pediatr Radiol 2006; 36:146-153 2496

Kim C, Vasaiwala S, Haque F, Pratap K, Vidovich MI. Radiation safety among 2497

cardiology fellows. Am J Cardiol 2010;106(1):125-128. 2498

Koenig TR, Mettler FA, Wagner LK. Skin injuries from fluoroscopically guided 2499

procedures: part 2, review of 73 cases and recommendations for minimizing dose 2500

delivered to patient. AJR Am J Roentgenol. 2001 Jul;177(1):13-20. 2501

McCollough CH, Schueler BA, Atwell TD, Braun NN, Regner DM, Brown DL, LeRoy 2502

AJ. Radiation exposure and pregnancy: when should we be concerned? 2503

RadioGraphics 2007; 27:9090-918. 2504

Miller DL, Balter S, Noonan PT, Georgia JD. Minimizing radiation-induced skin injury 2505

in interventional radiology procedures. Radiology 2002;225:329-36. 2506

Miller DL. Overview of contemporary interventional fluoroscopy procedures. Health 2507

Phys 2008, 95:638-644. 2508

Miller DL, Balter S, Schueler BA, Wagner LK, Strauss KJ, Vañó E. Clinical radiation 2509

management for fluoroscopically guided interventional procedures. Radiology 2010, 2510

in press. 2511

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Neofotistou V, Vano E, Padovani R, Kotre J, Dowling A, Toivonen M, Kottou S, 2512

Tsapaki V, Willis S, Bernardi G, Faulkner K. Preliminary reference levels in 2513

interventional cardiology. Eur Radiol. 2003 Oct;13(10):2259-63. 2514


management for fluoroscopically guided interventional medical procedures. NCRP 2516

Report No. 168. Bethesda, MD: National Council on Radiation Protection and 2517

Measurements; 2010. 2518

Neofotistou V. Review of patient dosimetry in cardiology. Radiat Prot Dosimetry. 2519

2001;94(1-2):177-82. 2520

Ortiz P, Vano E, Padovani R, Cotelo E, Ramirez A, Mota H, Faulkner K, Balter S. 2521

Influence of the interventional equipment performance on patient dose and image 2522

quality. Results of a survey under the IAEA International Action Plan for the 2523

Radiological Protection of Patients. ECR 2004. Vienna. Austria. 2524

Rehani MM. Training of interventional cardiologists in radiation protection—the 2525

IAEA‘s initiatives. Int J Cardiol 2007;114:256-260. 2526

Sidhu MK, Goske MJ, Coley BJ, Connolly B, Racadio J, Yoshizumi TT, Utley T, 2527

Strauss KJ. Image gently, step lightly: increasing radiation dose awareness in 2528

pediatric interventions through an international social marketing campaign. J Vasc 2529

Interv Radiol 2009; 20:1115-1119. 2530

Tsapaki V, Kottou S, Kollaros N, Dafnomili P, Kyriakidis Z, Neofotistou V. Dose 2531

performance evaluation of a charge coupled device and a flat-panel digital 2532

fluoroscopy system recently installed in an interventional cardiology laboratory. 2533

Radiat Prot Dosimetry. 2004;111(3):297-304. 2534

Tsapaki V, Kottou S, Vano E, Faulkner K, Giannouleas J, Padovani R, Kyrozi E, 2535

Koutelou M, Vardalaki E, Neofotistou V. Patient dose values in a dedicated Greek 2536

cardiac centre. Br J Radiol. 2003 Oct;76(910):726-30. 2537

Vano E, Arranz L, Sastre JM, Moro C, Ledo A, Garate MT, Minguez I. Dosimetric and 2538

radiation protection considerations based on some cases of patient skin injuries in 2539

interventional cardiology. Br J Radiol. 1998 May;71(845):510-6. 2540

Vano E, Goicolea J, Galvan C, Gonzalez L, Meiggs L, Ten JI, Macaya C. Skin radiation 2541

injuries in patients following repeated coronary angioplasty procedures. Br J Radiol. 2542

2001 Nov;74(887):1023-31. 2543

Vano E, Gonzalez L, Ten JI, Fernandez JM, Guibelalde E, Macaya C. Skin dose and 2544

dose-area product values for interventional cardiology procedures. Br J Radiol. 2001 2545

Jan;74(877):48-55. 2546

Vano E, Gonzalez L. Approaches to establishing reference levels in interventional 2547

radiology. Radiat Prot Dosimetry. 2001;94(1-2):109-12. 2548

Vano E, Guibelalde E, Fernandez JM, Gonzalez L, Ten JI. Patient dosimetry in 2549

interventional radiology using slow films. Br J Radiol. 1997 Feb;70:195-200. 2550

Vano E, Prieto C, Fernandez JM, Gonzalez L, Sabate M, Galvan C. Skin dose and dose-2551

area product values in patients undergoing intracoronary brachytherapy. Br J Radiol. 2552

2003 Jan;76(901):32-8. 2553

Vano E, Gonzalez L, Fernandez JM, Alfonso F, Macaya C.Occupational radiation doses 2554

in interventional cardiology: a 15-year follow-up. Br J Radiol. 2006;79(941):383-8. 2555


64

Vlietstra RE, Wagner LK, Koenig T, Mettler F. Radiation burns as a severe complication 2556

of fluoroscopically guided cardiological interventions. J Interv Cardiol. 2004 2557

Jun;17(3):131-42. 2558

Wagner LK and Archer BR. Minimising risks from fluoroscopic x rays. Third Edition. 2559

Partners in Radiation Management (R.M. Partnership). The Woodlands, TX 77381. 2560

USA 2000. 2561

Wagner LK, Archer BR, Cohen AM. Management of patient skin dose in 2562

fluoroscopically guided interventional procedures. J Vasc Interv Radiol 2000;11:23-2563

33. 2564

Wagner LK. Radiation injury is a potentially serious complication to fluoroscopically-2565

guided complex interventions. In: Biomedical Imaging and Intervention Journal. 2566

Lumpur, Malaysia: Dept. of Biomedical Imaging, University of Malaya; 2007:e22. 2567

Available at http://www.biij.org/2007/2/e22/ Accessed Aug 9, 2010 2568

Whitby M, Martin CJ. A study of the distribution of dose across the hands of 2569

interventional radiologists and cardiologists. Br J Radiol 2005;78:219-29. 2570

2571

2572

http://www.biij.org/2007/2/e22/


65

Figure 5.1 2573 Example of skin dose distribution in cardiology procedures (measured with slow film at 2574

the San Carlos University Hospital in Madrid). Skin dose distribution measured during a 2575

conventional PTCA. In this case the peak skin dose was 0.4 Gy. 2576

2577

2578

2579

2580

2581


66

Figure 5.2 2582

Example of a patient dose report produced by a Siemens Axiom Artis X ray system. 2583

Entries 1 to 5 indicate the series acquisition order. CARD is the name of the 2584

acquisition protocol. FIXED means a constant frame rate during the series run. Coro 2585

LD is the acquisition mode. Time in seconds is the duration of the series. Series frame 2586

rate, date, time of acquisition, kV, mA peak, pulse time, focus size, extra copper 2587

filter, KAP per series, RAK, X-ray beam angulation, and number of frames (for each 2588

series) are reported. Total fluoroscopy time, total KAP, and total RAK are also given 2589

at the end of the report. The original printing format of the X-ray system is 2590

maintained. 2591

2592

2593

2594

2595

2596

2597

2598


67

2599

Table 5.1 2600 Practical advice to reduce patient doses. 2601

2602

2603

Techniques to

reduce patient dose

Use a low-dose fluoroscopy mode when possible

Use the lowest-dose mode for image (cine) acquisition that is compatible with the

required image quality

Minimize fluoroscopy time—use fluoroscopy only to guide devices and observe

motion

Use the last-image-hold image for review when possible, instead of using

fluoroscopy

When possible, store a fluoroscopy loop instead of performing a cine run

If it is available, use a stored fluoroscopy loop for review instead of using

fluoroscopy

Minimize the number of cine series

Minimize the number of frames per cine series

Never use cine as a substitute for fluoroscopy

Collimate the radiation beam to the area of interest

Use virtual collimation if it is available

Use wedge filters when they are appropriate

Keep the image detector (image intensifier or flat detector) as close as possible to the

patient.

Keep the patient as far as possible from the x-ray tube.

Try to avoid steeply angulated projections (especially LAO cranial)

Try to vary the C-arm angulation slightly, to avoid concentrating the radiation dose

at a single site on the patient‘s skin.

Use magnification only when necessary.

Remember that for large patients, and also for steeply angulated projections, the

dose to the patient increases substantially.

Pay attention to the patient radiation dose display in the procedure room.

If the patient has had previous similar procedures, try to obtain information about the

previous radiation doses to optimise subsequent procedures.

2604

2605


68

6. RADIATION DOSES AND PROTECTION OF STAFF DURING 2606

INTERVENTIONAL FLUOROSCOPY 2607

2608

Main Points 2609

2610

In general, reducing patient dose will also reduce operator dose. 2611

The basic tools of occupational radiological protection are time, distance and 2612

shielding. 2613

The use of personal protective shielding is necessary in the cardiac 2614

catheterization laboratory. 2615

Radiological protection for the eyes is necessary for interventionalists. 2616

Occupational doses can be reduced to very low levels if ceiling suspended lead 2617

screens and protective lead curtains suspended from the side of the procedure 2618

table are used properly. 2619

Radiation exposure to the operator is neither uniform nor symmetric. 2620

Proper use of personal monitoring badges is necessary in cardiac 2621

catheterization laboratories in order to monitor and audit occupational 2622

radiation dose. 2623 2624


(97) Despite regulatory limits on occupational dose, there have been reports of 2626

cataracts and of fairly high radiation doses to the hands and legs of staff and hair loss in 2627

the portions of the legs not shielded by a protective device (Balter, 2001a). The 2628

occurrence of radiation-induced cataracts in operators (Vano et al. 1998a, Vano et al, 2629

2010, ICRP 2000, Ciraj-Bjelac, 2010) and the debate regarding the incidence of brain 2630

cancer in interventional cardiologists (Finkelstein, 1998, Klein et al, 2009) highlight the 2631

importance of occupational radiological protection for interventionalists, especially for 2632

parts of the body not protected by the lead apron. 2633

(98) The operator is not normally exposed to the x-ray beam directly, but is exposed 2634

to a considerable amount of scatter radiation. There are a number of techniques, 2635

described in Chapter 5, and protective devices, discussed in this Chapter, that, if used 2636

appropriately, should result in the operator‘s annual effective dose being well within 2637

regulatory limits. With proper use of radiological protection tools and techniques, the 2638

effective dose (E) for an interventionalist is typically 2–4 mSv/year, and is well below the 2639

20 mSv/year limit recommended by the Commission (Dendy, 2008, Tsapaki, 2004, 2640

Miller, 2010, ICRP 2007). Proper use of personal monitoring badges is essential in 2641

cardiac catheterization laboratories in order to monitor and audit occupational radiation 2642

dose. Too often, personal monitoring badges are not worn, or are worn improperly 2643

(Padovani, 2011). Training in radiation management and radiological protection, as 2644

discussed in Chapter 9, is essential (ICRP 2000). 2645


69

6.2 Comparison of radiation exposure with that of other staff 2646

(99) The interventionalist encounters much more radiation than most other medical 2647

and paramedical staff in a hospital. The radiation intensity from radioisotopes used in 2648

nuclear medicine is smaller by a factor of a few tens or even hundred. Nuclear medicine 2649

staff are likely to be exposed to much less radiation, whether it emanates from the patient 2650

or from external sources (normally in shielded containers). Similarly, while the radiation 2651

sources used in radiotherapy are of very high strength (GBq or TBq of radioactivity), 2652

staff are exposed only to remnant radiation leaking through the shielding material and 2653

scattered through a large distance. Staff in the interventional laboratory who are 2654

positioned in the control room are protected by both shielding and distance from the x-ray 2655

beam. Typically, in a properly designed facility, the radiation intensity in the control 2656

room may be tens of thousands of times less than at the operator‘s position (Rehani and 2657

Ortiz-Lopez, 2005). Exposure factors for the interventionalist are a thousand times higher 2658

than for staff working in the control room. 2659

(100) The major protection in nuclear medicine accrues from the lower radiation 2660

intensity and in radiotherapy from shielding and distance. The situation in interventional 2661

fluoroscopy is very different. First, the operator‘s working position is quite close to the x-2662

ray source and the source of scatter radiation (the patient). Second, the intensity of the x-2663

ray beam lies in between the radiation intensities observed in nuclear medicine and 2664

radiotherapy. Also, beam intensity is 10-fold or 20-fold higher in cine mode than in 2665

fluoroscopy mode (NCRP Report 168, 2010). Shielding plays a major role in radiological 2666

protection in interventional fluoroscopy, due to variability in the operator‘s distance from 2667

the x-ray source, the relative position of the operator, patient, and x-ray source and the 2668

duration of the procedure. 2669

6.3 The essentials of occupational radiological protection 2670

(101) The essentials of occupational radiological protection are time, distance and 2671

shielding. Staff radiological protection cannot be handled independently from patient 2672

protection, since they correlate in many ways. Both patient and occupational radiological 2673

protection are also discussed in an ICRP publication devoted to radiological protection 2674

outside the imaging department (reference ICRP TG 78). In general, reducing patient 2675

dose will also reduce operator dose. 2676

2677

(102) Time, one essential component of radiological protection, is controlled by 2678

reducing the time the x-ray beam is on, both for fluoroscopy and for cine. Reducing 2679

fluoroscopy time and fluoroscopy dose rate reduces patient dose. Reduced patient dose 2680

results in reduced scatter, and therefore in reduced operator dose. Readers are advised to 2681

remember all of the factors discussed in Chapter 4. 2682

(103) Distance is a valuable tool for radiological protection. Radiation dose 2683

decreases as the square of the distance between the radiation source and the operator (the 2684

inverse square law). A person who moves away from the x-ray source to three times the 2685

original distance will receive only one-ninth of the original dose. During a procedure, the 2686

operator cannot normally move further away from the patient than arm‘s length. This can 2687


70

result in high operator radiation doses, especially if contrast medium is injected manually 2688

for angiographic runs. However, if a mechanical injector is used for contrast medium 2689

injection, the operator can move back away from the patient, and ideally behind a shield. 2690

(104) In general, scattered radiation is most intense on the entrance beam side of the 2691

patient (Balter, 2001b, Schueler et al, 2006, Stratakis et al, 2006). When using a C-arm 2692

in a lateral projection, the operator should be positioned on the image receptor side of the 2693

patient, if possible. When using a C-arm in a frontal projection, positioning the x-ray 2694

tube below the table will place the area of higher radiation scatter towards the floor, so 2695

that the operator‘s head and neck receive less radiation. 2696

(105) Shielding is of three types: architectural shielding, equipment mounted shields, 2697

and personal protective devices (Miller et al, 2010). Architectural shielding is built into 2698

the walls of the procedure room and is not discussed further here. Rolling and stationary 2699

shields that are constructed of transparent leaded plastic and rest on the floor are useful 2700

for providing additional shielding for both operators and staff. They are particularly well 2701

suited for use by nurses and anaesthesia personnel. The interventionalist is protected by 2702

equipment-mounted shields suspended from the ceiling and the procedure table, and by 2703

personal protective devices such as a lead apron, leaded glasses and a thyroid shield. 2704

(106) Simple measures, such as standing a little away from the table and patient, 2705

limiting the field size (collimation) and carrying out procedures quickly consistent with 2706

case complexity can be very effective in reducing occupational radiation dose. Table 6.1 2707

presents some practical advice to improve occupational protection in the catheterization 2708

laboratory and Table 6.2 presents the relative change in scatter dose rates measured in a 2709

typical catheterization laboratory for different changes in technique. The values in Table 2710

6.2 highlight the large changes in scatter dose associated with changes in technique and 2711

patient body size. 2712

6.4 Personal protective devices 2713 2714

(107) The use of personal protective shielding is essential in the cardiac 2715

catheterization laboratory. In the past, there has been a trend to use lead aprons of higher 2716

lead equivalence (0.5 mm rather than 0.25, 0.3 or 0.35 mm), even though physical 2717

measurements did not demonstrate a great difference in attenuation (Table 6.3). The 2718

inherently conservative safety factor has always influenced practice in radiation, both for 2719

interventionalists and for regulators. 2720

(108) When procedures are performed on thinner patients, and in particular on 2721

children, a lead apron of 0.25 mm lead equivalence will suffice for staff protection, but 2722

for procedures performed on thicker patients, and for procedures performed by physicians 2723

with heavy workload, a 0.5 mm lead apron may be more suitable. Lead is very effective 2724

for protecting against radiation, but is heavy. The weight can cause problems for staff 2725

who have to wear these aprons for long spans of time (Goldstein, 2004). There are reports 2726

of back injuries due to lead aprons among staff who wear these aprons for many years 2727

(NCRP, 2010). Some newer aprons are lighter weight while maintaining approximately 2728

the same lead equivalence. Newer apron designs distribute weight using a variety of 2729

different methods. Two-piece (skirt and vest) wraparound aprons distribute the apron‘s 2730

weight and also provide protection for the wearer‘s back. 2731


71

(109) Lead aprons should be properly placed on designated hangers and should not 2732

be folded, creased, or crumpled in any way. Sitting on them, folding them or improperly 2733

hanging them may result in damage that reduces their effectiveness. Lead aprons, gloves 2734

and other leaded protective clothing should be inspected before they are put into service 2735

and then periodically re-inspected to determine that they provide the shielding benefit for 2736

which they were designed. A combination of visual, physical and fluoroscopic inspection 2737

can be employed to ensure the integrity of the garments. Consideration should be given to 2738

minimizing the irradiation of inspectors by minimizing unnecessary fluoroscopy (NCRP 2739

168, 2010). 2740

(110) A lead apron does not protect the eyes, the hands, the lower legs or the back 2741

(unless the apron is the wrap-around type). Radiation exposure of these parts of the 2742

body has become a concern. 2743

(111) Radiological protection for the eyes is essential for interventionalists (Dauer et 2744

al, 2010). Preferably, this protection is provided by ceiling-suspended shields (section 2745

6.3), as these devices protect the entire head, and not just the eyes. However, there are 2746

many procedures where it is not practical to use ceiling-suspended shields, as they 2747

interfere with the operator‘s ability to perform the procedure (Miller et al., 2010). In 2748

these situations, leaded eyeglasses should be worn. Wearing these eyeglasses has been 2749

shown to significantly reduce radiation dose to the operator‘s eyes (Vano et al, 2008; 2750

Thornton et al, 2010). 2751

(112) While the dose reduction factor for 0.5 mm lead equivalent protective glasses 2752

is approximately 0.03 (i.e., 97% of the radiation is attenuated) the extent of radiation 2753

attenuation by the eyeglass lenses is not an adequate descriptor, by itself, of the 2754

effectiveness of the eyewear (NCRP report 168, 2010). For maximum effectiveness, 2755

radiation protective eyewear should intercept as much as possible of the scattered 2756

radiation that is directed at the interventionalist‘s eyes. During interventional procedures, 2757

interventionalists normally turn their heads away from the primary beam to view the 2758

fluoroscopy monitor. This results in exposure of the eyes to scattered radiation from the 2759

side. Protective eyewear should provide shielding for side exposure, using either side 2760

shields or a wrap-around design (NCRP report 168, 2010). Proper fit is necessary to 2761

ensure that the lenses and side shields adequately protect the eye and minimize exposure, 2762

and is also important to minimize discomfort from the weight of the eyewear (Schueler et 2763

al., 2009). Even properly designed and fitted leaded eyewear attenuates scattered 2764

radiation by only a factor of 2 or 3 (Moore et al., 1980; Thornton et al, 2010). The net 2765

effect of protective eyeglasses is dependent on the design of the glasses, the nature of the 2766

clinical procedure, and the wearer‘s work habits. 2767

(113) In younger individuals, the thyroid gland is relatively sensitive to radiation-2768

induced cancer. However, the cancer incidence risk is strongly dependent on age at 2769

exposure, with very little risk after age 30 for males and age 40 for females (NRC, 2006). 2770

For younger workers, wearing a thyroid collar and a protective apron reduces effective 2771

dose to ~50 % of the effective dose achieved by wearing a protective apron alone 2772

(Martin, 2009; von Boetticher et al., 2009). Use of a thyroid collar (or a protective apron 2773

with thyroid coverage) is recommended for younger interventionalists and for all 2774


72

personnel whose personal monitor readings at the collar level (unshielded) exceed 4 mSv 2775

(E) in a month (Wagner, 2004). 2776

(114) Flexible, sterile, radiation-attenuating surgical gloves are available to reduce 2777

interventionalist hand exposure. A previous recommendation that protective gloves be 2778

worn in high exposure situations has been reconsidered (NCRP report 133, 2000, NCRP 2779

report 168, 2010). Attenuating surgical gloves may be used to provide a small degree of 2780

protection when hands are exposed only to scattered radiation, but the use of these gloves 2781

does not permit interventionalists to place their hands safely in the primary beam (NCRP 2782

168, 2010). 2783

(115) There are several factors that could lead to higher hand doses for 2784

interventionalists when these gloves are used (Miller et al, 2010). Just as with special 2785

tools that allow for increased distance between the hands of the interventionalist and the 2786

primary x-ray beam, the reduction in tactile feedback from radiation-attenuating surgical 2787

gloves may lead to an increase in fluoroscopy time or CT exposure time for delicate 2788

procedures. Because of the increased dose when any shielding is placed in the primary 2789

beam, and the false sense of security that these gloves provide, protective gloves can 2790

result in increased radiation dose to the hand when the gloved hand is in the primary 2791

beam (Wagner, 1996). With or without added protection, the hands should not be placed 2792

in the primary x-ray beam, except for those rare occasions when it is essential for the 2793

safety and care of the patient. This should be done for the shortest possible time. As a 2794

rule, if an operator‘s hands are visible on the monitor, then practices should be altered 2795

(Limacher et al. 1998). 2796

6. 5 Equipment-mounted shields 2797

(116) The standard equipment-mounted shields used in catheterization laboratories at 2798

present are ceiling suspended lead screens and protective lead curtains suspended from 2799

the side of the procedure table. If these tools are used properly, occupational doses can be 2800

reduced to very low levels. 2801

(117) A leaded glass or plastic screen placed between the patient and the operator 2802

protects the operator‘s eyes, head and neck. Properly placed shields have been shown to 2803

dramatically reduce operator eye dose (Maeder et al., 2006, Thornton et al, 2010). These 2804

screens can effectively replace both leaded eyewear and a thyroid shield. The screens 2805

add no weight to the operator, eliminating the ergonomic consequences of the protective 2806

equipment they replace. 2807

(118) When a frontal (posteroanterior) projection is used and the x-ray tube is below 2808

the procedure table, scatter dose rates under the table are 3-4 times higher than the values 2809

over the table (Schueler et al, 2006). Leaded curtains suspended from the procedure table 2810

should be used to protect the interventionalist‘s lower legs. At present, these shields are 2811

available in almost all interventional suites. 2812

(119) Disposable, lightweight, sterile, lead-free radiological protection drape or pad 2813

shields can be positioned on the patient outside of the beam path to significantly reduce 2814

scattered radiation during cardiac interventional procedures (Sawdy et al, 2009, Germano 2815

et al, 2005). These contain metallic elements (typically bismuth or tungsten-antimony) 2816

and are placed on the patient after the operative site has been prepared and draped. They 2817


73

have been shown to reduce operator dose substantially, with reported reductions of 12-2818

fold for the eyes, 26-fold for the thyroid and 29-fold for the hands (King et al, 2002, 2819

Dromi et al, 2006). While their use adds some cost to the procedure, disposable 2820

protective drapes should be considered for complex procedures and procedures where the 2821

operator‘s hands must be near the radiation field (e.g., pacemaker placement) (Miller et 2822

al., 2010). In some institutions they are used routinely (Kim et al, 2010). These drapes 2823

should not be visible in the fluoroscopic image. If they are, the result will be an increase 2824

in patient dose. 2825

6.6 Overall impact of protective devices 2826

(120) The effective dose (E) to the cardiologist per procedure has been reported to 2827

range from 0.2 to 18.8 Sv (Padovani and Rodella, 2001). A more recent review 2828

demonstrated a range of 0.02 to 38.0 Sv (Kim et al, 2008). The wide dose ranges are 2829

most likely due to both the wide variation in procedure complexity and the inconsistent 2830

use of shields and personal protective devices. Modest operator dose reductions over 2831

time were observed for both diagnostic catheterizations and ablation procedures, due to 2832

technological improvements, but doses were not reduced over time for percutaneous 2833

coronary interventions. This was believed to be due mainly to the increased complexity 2834

of interventions. 2835

(121) Even if one assumes a rather high workload of 1000 angiographic procedures 2836

per year, the annual threshold level of 20 mSv will rarely be exceeded. One study 2837

reported an estimate of E for the operator of only 0.04–0.05 mSv/year (Efstathopolous et 2838

al. 2003), although other studies have reported 2–4 mSv/year (Dendy, 2008, Tsapaki, 2839

2004). The extensive studies by Kuon et al. establish that with proper choice of technique 2840

and shielding devices, the operator may be exposed to only 0.8% of typical radiation 2841

levels in advanced cardiac catheterization laboratories (Kuon et al. 2002). 2842

(122) When a lateral projection or steep gantry angulation is used, standing on the x-2843

ray tube side of the C-arm increases operator dose. Kuon et al. have estimated the 2844

influence of angulation of the X-ray tube on the amount of scatter radiation to the 2845

operator (Kuon et al. 2004). Radiation levels have been found to be highest for the left 2846

anterior oblique (LAO) position, whereas in posteroanterior (PA) and right anterior 2847

oblique (RAO) angulations, levels are much lower (Kuon et al. 2002, 2003, 2004). 2848

Simultaneous craniocaudal angulation further increases the dose. The group has shown 2849

that the standard view for the left main stem coronary artery (LAO 60°/20°–) is 2850

associated with a 7.6-fold increase in dose to the operator and a 2.6-fold increase in dose 2851

for the patient as compared to an alternative less frequently used angulation (caudal 2852

PA0°/30°–). 2853

(123) Effective dose does not reflect the doses to susceptible, unprotected parts of the 2854

body—the hands and the eyes. Radiation exposure to the operator is neither uniform nor 2855

symmetric. A right-handed operator performing the procedure via the right femoral 2856

artery has his or her left side turned towards the patient. Therefore the left side of the 2857

body is exposed to the highest level of scatter radiation (Maeder et al. 2005). This is 2858

especially true for the hands, which are at the level where the X-ray beam enters the 2859


74

patient. During cardiac catheterization, the left hand has been reported to receive twice 2860

the dose as compared with the right hand (Vaño et al. 1998b). The left eye also receives 2861

higher doses than the right eye. Not surprisingly, a tall operator will receive a lower eye 2862

dose than a short operator, because of the greater distance from the tall operator‘s eyes to 2863

the patient. 2864

(124) Unless personal monitoring devices are always worn, and worn properly, it is 2865

not possible to estimate occupational dose accurately. Failure to wear personal 2866

monitoring devices may lead to the false belief that an individual‘s occupational dose is 2867

low when it is not. 2868

6.7 Personal dosimetry 2869

(125) The Commission recommends the use of two personal dosimeters for 2870

occupational dosimetry cardiac catheterization laboratories: one worn on the trunk of the 2871

body inside the apron and the other worn outside the apron at the level of the collar or the 2872

left shoulder (ICRP 2000). The dosimeter under the apron provides an estimate of the 2873

dose to the organs of the shielded region. The dosimeter worn outside the apron supplies 2874

an estimate of the dose to the organs of the head and neck, including the thyroid and lens 2875

of the eyes (if unshielded), but greatly overestimates the doses to organs of the trunk. 2876

Results obtained from both dosimeters can be used to estimate the occupational effective 2877

dose as recommended by the NCRP (NCRP, 1995) and ICRP (ICRP, 2000). A dosimeter 2878

for the hands may also be useful. 2879

(126) The effective dose, E, can be estimated from the dosimeter values for Hw 2880

(under the apron at the waist, although this position is not critical) and Hn (above the 2881

apron at the neck) from the equation: 2882

2883

E = 0.5 Hw + 0.025 Hn 2884

2885

(127) NCRP report 122 (NCRP 1995) contains specific recommendations for 2886

calculating the effective dose when protective aprons are worn during diagnostic and 2887

interventional medical procedures involving fluoroscopy. In addition to the above 2888

formula, it states that the effective dose can be estimated as Hn/21 if only one dosimeter 2889

is worn on the neck outside the apron. 2890

(128) The European Commission DIMOND project addressed the issues regarding 2891

optimization of staff doses with an attempt to propose preliminary occupational dose 2892

constraints (Tsapaki at al. 2004). The proposed value for cardiologists' annual effective 2893

dose was 0.6 mSv. UNSCEAR (UNSCEAR 2000, paragraph 166) reported that 2894

cardiologists tend to be the most exposed staff in medicine; their average annual dose was 2895

0.4mSv, and an appreciable proportion received more than 1 mSv. A recent review of 2896

radiation exposures to operators from cardiac procedures over a 30 year period 2897

highlighted the difficulty in comparing reported dosimetry results because of significant 2898

differences in dosimetric methods in each study (Kim et al, Health Physics, 2008). Better 2899

standardization of dosimetric methods is recommended. 2900

(129) Many operators not only do not use protective equipment properly, but also do 2901

not regularly wear their dosimeters. Failure to wear dosimeters is a problem throughout 2902


75

the world (Vaño et al. 1998b, McCormick, 2002, Padovani, 2011). In addition to 2903

monitoring personal exposure, dosimeter use helps to increase awareness about 2904

radiological protection. In the absence of formal training in radiological protection for 2905

cardiologists in such countries, physicians in training adopt the practices of their seniors 2906

(Rehani and Ortiz-Lopez, 2005). 2907

(130) Compliance with the radiation badge policies is one of the main problems in 2908

many interventional cardiology services (Vano 2005). Reported occupational dose values 2909

are often surprisingly low, and the reason is likely not a high level of radiological 2910

protection, but rather failure to wear personal dosimeters. McCormick et al. (McCormick 2911

2002) reported that before a mandatory radiological protection training programme, 2912

compliance with the radiation badge policy for physicians and nurse clinicians was only 2913

36% in 1999, and afterwards reached a maximum of only 77%. A strict policy on the 2914

regular use of personal dosimeters should be part of any quality programme in cardiology 2915

laboratories. 2916

6.8 References 2917

2918

Balter, S, 2001a. Interventional fluoroscopy – physics, technology, safety. Wiley-Liss, 2919

New York. 2920

Balter S., 2001b. Stray radiation in the cardiac catheterization laboratory. Radiat Prot 2921

Dosim 94(1-2), 183-188. 2922

Ciraj-Bjelac O, Rehani MM, Sim KH, Liew HB, Vano E, Kleiman NJ. Risk for radiation 2923

induced cataract for staff in interventional cardiology: Is there reason for concern? 2924

Catheter Cardiovasc Interv 2010;76(6):826-834. 2925

Dauer, L.T., Thornton, R.H., Solomon, S.B., St Germain, J., 2010. Unprotected operator 2926

eye lens doses in oncologic interventional radiology are clinically significant: 2927

estimation from patient kerma-area-product data. J. Vasc. Interv. Radiol. 21, 1859-2928

1861. 2929

Dendy PP. Radiation risks in interventional radiology. Br J Radiol 2008; 81:1-7. 2930

Dromi, S., Wood, B.J., Oberoi, J., Neeman, Z., 2006. Heavy metal pad shielding during 2931

fluoroscopic interventions. J. Vasc. Interv. Radiol. 17, 1201-1206. 2932

Efstathopoulos E, Makrygiannis SS, Kottou S, et al. Medical personnel and patient 2933

dosimetry during coronary angiography and intervention. Phys Med Biol 2934

2003;48:3059-68. 2935

Finkelstein MM. Is brain cancer an occupational disease of cardiologists? Can J Cardiol 2936

1998;14,1385-8. 2937

Germano, J.J., Day, G., Gregorious, D., Natarajan, V., Cohen, T., 2005. 2938

A novel radiation protection drape reduces radiation exposure during fluoroscopy guided 2939

electrophysiology procedures. J. Invasive Cardiol. 17, 469-72. 2940

Goldstein JA, Balter S, Cowley M, Hodgson J, Klein LW; Occupational hazards of 2941

interventional cardiologists: prevalence of orthopedic health problems in 2942

contemporary practice. Catheter Cardiovasc Interv. 2004 Dec;63(4):407-11. 2943

ICRP. Avoidance of radiation injuries from medical interventional procedures. ICRP 2944

Publication 85. Ann ICRP 2000;30(2). 2945


76

ICRP. The 2007 Recommendations of the International Commission on Radiological 2946

Protection. ICRP Publication 103. Ann ICRP 2007; 37(2-4):1-332 2947



procedures. Health Phys 94: 211-227, 2008. 2950

Kim, C., Vasaiwala, S., Haque, F., Pratap, K., Vidovich, M.I., 2010. Radiation safety 2951

among cardiology fellows. Am. J. Cardiol. 106, 125-128. 2952

King JN, Champlin AM, Kelsey CA, Tripp DA. Using a sterile disposable protective 2953

surgical drape for reduction of radiation exposure to interventionalists. Am J 2954

Roentgenol 2002; 178:153-157. 2955

Klein LW, Miller DL, Balter S, Laskey W, Haines D, Norbash A, Mauro MA, Goldstein 2956

JA. Occupational health hazards in the interventional laboratory: time for a safer 2957

environment. Heart Rhythm 2009, 6:439-444. 2958

Kuon E, Schmitt M, Dahm JB. Significant reduction of radiation exposure to operator 2959

and staff during cardiac interventions by analysis of radiation leakage and improved 2960

lead shielding. Am J Cardiol 2002; 89:44-9. 2961

Kuon E, Dahm J, Empen K, et al. Identification of less-irradiating tube angulations in 2962

invasive cardiology. J Am Coll Cardiol 2004;44:1420-8. 2963

Limacher MC, Douglas PS, Germano G, et al. ACC expert consensus document. 2964

Radiation safety in the practice of cardiology. J Am Coll Cardiol. 1998;31:892-913. 2965

Maeder M. Verdun FR, Stauffer JC et al. Radiation exposure and radiation protection in 2966

interventional cardiology. Kardiovaskuläre Medizin 2005;8:124-132. 2967

Maeder M, Brunner-La Rocca HP, Wolber T, Ammann P, Roelli H, Rohner F, Rickli H. 2968

Impact of a lead glass screen on scatter radiation to eyes and hands in interventional 2969

cardiologists. Catheter Cardiovasc Interv 2006; 67:18-23. 2970

Marshall NW, Faulkner K, Clarke P. An investigation into the effect of protective 2971

devices on the dose to radiosensitive organs in the head and neck. Br J Radiol. 1992 2972

Sep;65(777):799-802. 2973

Martin, CJ. A review of radiology staff doses and dose monitoring requirements. Radiat 2974

Prot Dosim 2009; 136(3), 140-157. 2975

McCormick VA, Schultz CC, Hollingsworth-Schuler V, Campbell JM, O‘Neill WW, 2976

Ramos R. Reducing radiation dose in the cardiac catheterization laboratory by 2977

design alterations and staff education. Am J Cardiol 2002; 90:903-905. 2978

Miller DL, Vañó E, Bartal G, Balter S, Dixon R, Padovani R, Schueler B, Cardella JF, 2979

de Baère T. Occupational radiation protection in interventional radiology: A joint 2980

guideline of the Cardiovascular and Interventional Radiology Society of Europe and 2981

the Society of Interventional Radiology. Cardiovasc Interv Radiol 2010; 33:230-2982

239. 2983

Moore WE, Ferguson G, Rohrmann C. Physical factors determining the utility of 2984

radiation safety glasses. Med Phys 1980; 7(1), 8-12. 2985

NRC. Health risks from exposure to low levels of ionizing radiation: Phase 2, BEIR VII. 2986

Washington, DC: The National Academies Press, 2006. 2987

NCRP. Use of personal monitors to estimate effective dose equivalent and effective dose 2988

to workers for external exposure to low-LET radiation. NCRP report No. 122. 2989


77

Bethesda, Maryland: National Council on Radiation Protection and Measurements; 2990

1995. 2991

NCRP. Radiation protection for procedures performed outside the radiology department. 2992

NCRP Report No. 133. Bethesda, Maryland: National Council on Radiation 2993


NCRP. Radiation dose management for fluoroscopically guided interventional medical 2995

procedures. NCRP Report No. 168. Bethesda, MD: National Council on Radiation 2996


Padovani R, Rodella CA. Staff dosimetry in interventional cardiology. Radiat Prot 2998

Dosimetry 2001;94:99-103. 2999

Padovani, R., Le Heron, J., Cruz-Suarez, R., Duran, A., Lefaure, C., Miller, D.L., Sim, 3000

H.K., Vano, E., Rehani, M., Czarwinski, R., 2010. International project on individual 3001

monitoring and radiation exposure levels in interventional cardiology. Radiat Prot 3002

Dosimetry 2011; in press. 3003

Rehani MM, Ortiz-Lopez P. Radiation effects in fluoroscopically guided cardiac 3004

interventions – keeping them under control.(Editorial). Int J Cardiol 2006; 109(2): 3005

147-151. 3006

Sawdy, J.M., Gocha, M.D., Olshove, V., Chisolm, J.L., Hill, S.L., Phillips, A., 3007

Galantowicz, M., Cheatham, J.P., Holzer, R.J., 2009. Radiation protection during 3008

hybrid procedures: innovation creates new challenges. J. Invasive Cardiol. 21, 437-3009

40. 3010

Schueler BA, Vrieze TJ, Bjarnason H, Stanson AW. An investigation of operator 3011

exposure in interventional radiology. RadioGraphics 2006; 26(5), 1533-1541. 3012

Schueler BA, Sturchio G, Landsworth R, Hindal M, Magnuson D. (2009) Does new 3013

lightweight leaded eyewear provide adequate radiation protection for fluoroscopists? 3014

(abstract) Med Phys 2009; 36(6), 2747-2748. 3015

Stratakis J, Damilakis J, Hatzidakis A, Theocharopoulos N, Gourtsoyiannis N. 3016

Occupational radiation exposure from fluoroscopically guided percutaneous 3017

transhepatic biliary procedures. J Vasc Interv Radiol 2006; 17(5), 863–871. 3018

Thornton, R.H., Dauer, L.T., Altamirano, J.P., Alvarado, K.J., St. Germain, J., Solomon, 3019

S.B., 2010. Comparing strategies for operator eye protection in the interventional 3020

radiology suite. J. Vasc. Interv. Radiol. 21, 1703-1707. 3021

Tsapaki V, Kottou S, Vano E, Komppa T, Padovani R, Dowling A, Molfetas M, 3022

Neofotistou V. Occupational dose constraints in interventional cardiology 3023

procedures: the DIMOND approach. Phys Med Biol. 2004 Mar 21;49(6):997-1005. 3024

United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and 3025

effects of ionizing radiation. UNSCEAR 2000 report to the General Assembly, with 3026

scientific annexes. Annex E. Occupational radiation exposures. (Available at 3027

www.unscear.org). New York: United Nations; 2000. 3028

Vano E, González L, Beneytez F, et al. Lens injuries induced by occupational exposure 3029

in non-optimised interventional radiology laboratories. Br J Radiol 1998a;71:728-33. 3030

Vano E, Gonzalez L, Guibelalde E, et al. Radiation exposure to medical staff in 3031

interventional and cardiac radiology. Br J Radiol 1998b;71:954-60. 3032


78

Vano E. Radiation exposure to cardiologists: how it could be reduced. Heart. 2003; 3033

89(10):1123-4. 3034

Vano E, Gonzalez L, Fernandez JM, Alfonso F, Macaya C. Occupational radiation 3035

doses in interventional cardiology: a 15 year follow-up. Br J Radiol 3036

2006;79(941):383-388. 3037

Vano E, Gonzalez L, Fernandez JM, Prieto C, Guibelalde E. Influence of patient 3038

thickness and operation modes on occupational and patient doses in interventional 3039

cardiology. Radiat Prot Dosim 2006; 118(3): 325-330. 3040

Vano E, Gonzalez L, Fernandez M, Haskal ZJ. Eye lens exposure to radiation in 3041

interventional suites: caution is warranted. Radiology 2008; 248: 945-953. 3042


cataract risk in interventional cardiology personnel. Radiat Res, 2010; 174(4):490-3044

495 3045

von Boetticher H, Lachmund J, Hoffmann W. Cardiac catheterization: impact of face 3046

and neck shielding on new estimates of effective dose. Health Phys 2009; 97(6), 3047

622– 627. 3048

Wagner LK, Mulhern OR. Radiation-attenuating surgical gloves: effects of scatter and 3049

secondary electron production. Radiology 1996; 200:45-48. 3050

Wagner LK, Archer BR. Minimizing Risks from Fluoroscopic X-Rays: Bioeffects, 3051

Instrumentation, and Examination. 4th Edition. The Woodlands, Texas:(Partners in 3052

Radiation Management, 2004. 3053

3054


79

3055

Table 6.1. 3056

3057

Practical advice for interventionalists to improve staff radiation protection (from Vano et 3058

al, 2003 and Miller et al, 2010). 3059

3060

Increase your distance from the patient (the scatter radiation source) whenever 3061

possible. This is obviously only possible when angiographic runs are not performed 3062

by hand. Working at 80 cm from the isocenter instead of 40 cm can decrease scattered 3063

dose to approximately a quarter of the original dose. 3064

Try to position yourself in a low scatter area. Scattered radiation is higher at the x-3065

ray tube side of the gantry and lower on the side of the image receptor. 3066

Use a ceiling suspended screen, a table-suspended screen and other protective 3067

shielding, such as a lead apron, thyroid collar and lead glasses, when possible. 3068

When appropriate, use a dose reduction pad or drape at the catheter entrance site to 3069

reduce your hand dose. 3070

Minimise the use of fluoroscopy and use low-dose fluoroscopy modes (for example, 3071

pulsed fluoroscopy) when possible. 3072

Minimize the number of cine series and the number of frames per cine series. 3073

Use magnification as little as possible. 3074

Collimate the x-ray beam as tightly as possible. 3075

Obtain appropriate training in radiation management and radiation protection. 3076

Wear your dosimeters and know your own dose. 3077

In addition, a final general concept: reduce the patient‘s radiation and you will also be 3078

reducing your own dose. 3079

3080

3081


80

Table 6.2 3082

3083

Relative increases in staff doses with changes in different operational features in a Philips 3084

Integris 5000 fluoroscopy unit (Vano et al, 2006). 3085

3086

Action Increase in

staff dose

Changing from low to high fluoroscopy mode

(for a 20 cm thick patient)

× 2.6

Changing II format from 23 cm to 17 cm (for

a 20 cm thick patient)

× 1.0

Changing patient thickness from 16 to 28 cm × 4.2

Changing from low fluoroscopy mode to cine

(for a 20 cm thick patient)

× 8.3

3087

3088

3089


81

Table 6.3 3090

3091

Protection of different lead aprons for X-ray beams filtered with 3 mm Al and generated 3092

at the kVp indicated (Vano et al, 2006). 3093

3094

kVp Protective apron

Pb equivalent (mm) Fraction of energy transmitted (%)

90 0.25 8.3

90 0.35 4.9

90 0.50 2.4

80 0.25 5.7

80 0.35 3.0

80 0.50 1.3

70 0.25 3.3

70 0.35 1.5

70 0.50 0.5

3095

3096


82

3097

7. RADIOLOGICAL PROTECTION FOR NUCLEAR CARDIOLOGY 3098

3099

Main Points 3100

Appropriate use criteria and guidelines that help to set standards for 3101

justification have been developed through consensus efforts of professional 3102

societies. 3103

Optimization of nuclear cardiology procedures involves the judicious 3104

selection of radiopharmaceuticals and administered activities to ensure 3105

diagnostic image quality while minimizing patient dose. 3106

For SPECT protocols, Tc-99m-based agents yield lower effective doses than 3107

Tl-201, and are preferred on dosimetric grounds. 3108

Administered activities should be within pre-specified ranges, as provided in 3109

international and national guidelines, and should reflect patient habitus. 3110

If stress imaging is normal, rest imaging can be omitted to minimize total 3111

dose. 3112

Practitioners need good quality dosimetry data to perform proper benefit-3113

risk analyses for their patients. 3114 3115

3116


(131) More than 90% of nuclear cardiology studies are myocardial perfusion 3119

scintigraphy studies for the assessment of myocardial perfusion and/or viability. The vast 3120

majority of nuclear cardiology procedures are performed with single photon emission 3121

computed tomography (SPECT). A small but growing number of laboratories perform 3122

positron emission tomography (PET) studies. 3123

(132) An estimated 32.7 million diagnostic nuclear medicine procedures are 3124

performed annually worldwide (UNSCEAR 2008). Of these, approximately 14 million 3125

are nuclear cardiology procedures, and this number has increased rapidly (Davis, 2006). 3126

More nuclear cardiology procedures are performed in the United States than in the rest of 3127

the world combined. In the U.S., nuclear medicine procedures accounted for 26% of the 3128

medical exposure of patients in 2006, and cardiac studies accounted for 85% of the 3129

nuclear medicine exposure (NCRP report 160, 2009). 3130

3131

7.2 Radiopharmaceuticals 3132

3133 (133) The radiopharmaceuticals used most commonly for nuclear cardiology studies 3134

are summarized in Table 7.1. In Europe, most studies are performed using Tc-99m-3135

based agents, while in the United States, a sizable minority of studies are performed using 3136

Tl-201, usually in the context of a dual isotope study with rest Tl-201 imaging followed 3137

by stress Tc-99m imaging. The use of thallium results in a higher dose to the patient 3138

(Einstein et al, 2007). 3139

3140


83

Table 7.1. Commonly Used Radiopharmaceuticals for Nuclear Cardiology 3141

Agent Modality

Role

Physical

Half-Life

Effective Dose

(10-3 mSv/MBq)

ICRP

Publication (14) P

erfusion

(15) F

unctio

n

(16) V

iabilit

y

Tc-99m sestamibi SPECT +++ ++ + 6h 9.0 rest/7.9

stress 80(1998)

Tc-99m tetrofosmin SPECT +++ ++ + 6h 7.6 rest/7.0

stress 80(1998)

Tl-201 SPECT +++ + ++ 73h 140 106(2008)

Tc-99m red blood

cells

Planar or

SPECT

MUGA

- +++ - 6h 7.0 80(1998)

Rb-82 PET +++ ++ - 75s 3.4* (17) 8

0(1998)*

N-13 ammonia PET +++ ++ - 10m 2.0 80(1998)

F-18

fluorodeoxyglucose PET - - +++ 110m 19 (18) 8

0(1998)

SPECT: single photon emission computed tomography, PET: positron emission tomography: MUGA: multiple gated 3142 acquisition 3143 * ICRP‘s dose coefficients for Rb-82, dating to Publication 53 (1987) and reiterated in Publication 80 (1998), reflect 3144 for some organs ―worst case‖ conditions, as was stated in Publication 53, and thus dose estimates deriving therefrom 3145 might be overly conservative. Three groups have recently suggested lower dose coefficients (Senthamizhchelvan et al 3146 2010, 1.11 μSv/MBq; Hunter 2010, 0.74 μSv/MBq; and Stabin 2010, 1.7 μSv/MBq); the Commission is currently 3147 revisiting the issue of Rb-82 dosimetry. 3148 3149

(134) Recommended administered activities for nuclear cardiology procedures vary 3150

markedly among the professional societies and accrediting bodies in various countries 3151

(Hesse et al., 2005). Guidelines have been published by both the American Society of 3152

Nuclear Cardiology (ASNC) (DePuey, 2006; Henzlova, 2009) and the European Council 3153

on Nuclear Cardiology (ECNC) (Hesse et al., 2005), a joint group of the European 3154

Association of Nuclear Medicine (EANM) and the European Society of Cardiology 3155

(ESC). Injected activity from these guidelines is summarized in Table 7.2. 3156

3157

3158

3159

3160

3161

3162

3163

3164

3165

3166

3167

3168

3169

3170

3171

3172


84

Table 7.2. Recommended Injected Activity (MBq) for Standard Cardiac SPECT and PET 3173

Protocols 3174

3175

3176

3177 *740 to 925 for planar imaging 3178

**for 2 dimensional acquisition using camera with bismuth germanate or lutetium 3179

oxyorthosilicate crystals 3180

3181

7.3 Dosimetry for nuclear cardiology 3182

3183 (135) Two types of dose coefficients can be determined: 1) tissue dose coefficients, 3184

which can be used to estimate the dose to a particular tissue or organ, and 2) effective 3185

dose coefficients, which can be used to estimate effective dose to the individual. Note 3186

however that effective dose is intended for use as a radiological protection quantity. 3187

Effective dose is not recommended for epidemiological evaluations, nor should it be used 3188

for detailed specific retrospective investigations of individual exposure and risk (ICRP, 3189

2007a). 3190

(136) Estimates of organ dose and estimates of effective dose to patients are 3191

generally obtained by using mathematical biokinetic models that quantify the distribution 3192

and metabolism of a radiopharmaceutical in the body. These models incorporate 3193

biokinetic data from humans and/or animals and enable the determination of dose 3194

coefficients. 3195

(137) Tissue dose coefficients quantify absorbed doses to a specific organ in a typical 3196

patient, per unit activity administered. For example, ICRP‘s current liver dose coefficient 3197


85

in an adult for the PET tracer F-18 fluorodeoxyglucose is 1.110-2

mGy per MBq (ICRP, 3198

1998). Thus, a 200 MBq injection of F-18 fluorodeoxyglucose is associated with an 3199

estimated dose to the liver of 2.2 mGy. 3200

(138) Effective dose coefficients quantify effective dose per unit activity 3201

administered. ICRP‘s current effective dose coefficient in an adult for F-18 3202

fluorodeoxyglucose is 1.910-2

mSv per MBq (ICRP, 1998), and therefore the same 200 3203

MBq injection of F-18 fluorodeoxyglucose would be associated with an estimated 3204

effective dose of 3.8 mSv. 3205

(139) Several systems provide mathematical frameworks for estimating dose 3206

coefficients, including those of ICRP Publication 30 (ICRP, 1979) and those of the 3207

Society of Nuclear Medicine‘s Medical Internal Radiation Dose committee (Loevinger et 3208

al., 1988) and Radiation Dose Assessment Resource task group (Stabin et al., 2001). 3209

These approaches are essentially equivalent (Stabin, 2006). They estimate radiation dose 3210

as energy per unit mass. Energy is generally determined from biokinetic models of the 3211

radiopharmaceutical‘s time-activity curve, from tables of the mean energy per nuclear 3212

transition, and from Monte Carlo computer models. Organ masses are determined from a 3213

model of a representative person. 3214

(140) There are numerous collections of dose coefficients for specific 3215

radiopharmaceuticals. The most extensive compilations are those of the Commission, for 3216

which current estimates can be found in Publications 53 (ICRP, 1987), 80 (ICRP, 1998), 3217

and 106 (ICRP, 2008). Effective doses for commonly used radiopharmaceuticals for 3218

nuclear cardiology, based on the most recent ICRP effective dose coefficients for these 3219

radiopharmaceuticals, are listed in Table 7.1. These effective doses reflect ICRP 3220

Publication 60 tissue weighting factors; updated effective dose coefficients reflecting 3221

Publication 103 tissue weighting factors will be included in a forthcoming ICRP 3222

publication. In many countries there is a regulatory requirement that dose coefficients be 3223

provided in manufacturers‘ package inserts/product information (PI) sheets for 3224

radiopharmaceuticals. 3225

3226

7.4 Current dosimetry estimates 3227

3228 (141) The dose to a typical patient from a nuclear cardiology study can be estimated 3229

by multiplying dose coefficients by the administered activity. These estimates are 3230

illustrated in Figure 7.1, using the most recent ICRP dose coefficients for each agent and 3231

administered activities in the middle of the range specified in Table 7.2. 3232

3233

3234

3235


86

3236

3237 3238 Figure 7.1. Effective doses from standard nuclear cardiology procedures, estimated using the most recent 3239 ICRP dose coefficients and Publication 103 tissue weighting factors (ICRP, 2007a). Stacked bars represent 3240 organ weighted equivalent doses contributing to effective dose. Doses for Tc-99m represent the average of 3241 Tc-99m sestamibi and tetrofosmin. Top: Using average recommended administered activities from 3242 American Society of Nuclear Cardiology guidelines (Henzlova, 2009; DePuey, 2006). Bottom: Using 3243 average recommended administered activities from European Council on Nuclear Cardiology guidelines 3244 (Hesse et al., 2005). 3245 3246 *Note that ICRP‘s dose coefficients for Rb-82, dating to Publication 53 (1987) and reiterated in Publication 3247 80 (1998), reflect for some organs ―worst case‖ conditions, as was stated in Publication 53, and thus dose 3248 estimates derived therefrom might be overly conservative. Three groups have recently suggested lower 3249 dose coefficients (Senthamizhchelvan et al 2010, 1.11 μSv/MBq; Hunter 2010, 0.74 μSv/MBq; and Stabin 3250 2010, 1.7 μSv/MBq); the Commission is currently revisiting the issue of Rb-82 dosimetry. 3251 3252


87

3253

3254

7.5 Uncertainty in dosimetry 3255

3256 (142) Because many terms are estimated and multiplied together to determine dose 3257

coefficients, there are numerous potential sources of uncertainty in these dose estimates. 3258

Differences between planned and actual administered activity are considered to be minor 3259

contributors to the total uncertainty, if regular quality control is performed (ICRP, 1987). 3260

The three most sizable contributors to uncertainty are inter-individual variability in organ 3261

masses, absorbed fractions, and total activity in each organ. Uncertainties in organ 3262

activity reflect differences in biokinetics. (Stabin, 2008b) Experimental validation of 3263

calculated absorbed doses has indicated agreement within 20% to 60%, with the larger 3264

value applicable to patients who differed considerably from the body size and shape 3265

assumed in the calculations (Roedler, 1981). More recent publications contend that the 3266

combined uncertainties for any given dose estimate of a radiopharmaceutical are 3267

generally at least a factor of 2 (Stabin, 2008b). 3268

3269

7.6 Discrepancies between ICRP dosimetry and information from 3270

manufacturers 3271

3272 (143) The most readily available source of dosimetric data about a 3273

radiopharmaceutical is typically the information provided by the manufacturer. In 3274

several cases, dose coefficients vary considerably between those given in ICRP 3275

publications and those provided by manufacturers. These discrepancies may affect the 3276

choice of diagnostic tests and the choice of radiopharmaceuticals, since radiation risk is 3277

one factor that should be incorporated into benefit-risk analyses. 3278

(144) One recent report evaluating package inserts in the United States found that 3279

effective doses for Tl-201 estimated from a single manufacturer‘s information were less 3280

than half of those estimated from ICRP tables, while doses estimated from package 3281

inserts from two other manufacturers were greater than or similar to ICRP effective 3282

doses.(Einstein et al., 2007) These discrepancies are due, in part, to the numerous 3283

sources of uncertainty incorporated into dose coefficients. However, they may also be 3284

due to the use of limited and older data by manufacturers (Gerber et al., 2009; Stabin, 3285

2008a). 3286

(145) The Commission recommends that national regulatory authorities implement 3287

programs to ensure the quality of dosimetric data in package inserts and product 3288

information. Aspects of quality include inclusion of effective dose coefficients (as 3289

opposed to total body dose coefficients), periodic post-approval updates to reflect the 3290

available dosimetric data, and transparency in the data sources and sample sizes used to 3291

obtain dose coefficients. 3292

3293

7.7 Radiological protection of patients in nuclear cardiology 3294

3295


88

(146) The general principles of radiological protection (chapter 4), i.e. justification 3296

and optimisation, can be applied to the protection of patients in nuclear cardiology. Dose 3297

limitation is not appropriate, but diagnostic reference levels should be used to help 3298

manage the radiation dose so that the dose is commensurate with the clinical purpose 3299

(ICRP, 1977, ICRP, 2007a, ICRP, 2007b). 3300

3301

7.7.1 Justification 3302

3303 (147) Nuclear cardiology studies should always be justified on clinical grounds 3304

(Gerber et al., 2009). Even in highly expert institutions, sizable percentages of nuclear 3305

cardiology studies performed may not meet standardized criteria for appropriateness. To 3306

a certain degree this may reflect limitations with appropriateness criteria, which may not 3307

incorporate all the information included in decision making for a particular patient. 3308

However, in a recent retrospective analysis of 284 patients undergoing nuclear stress 3309

testing at the Mayo Clinic, 25% had inappropriate or uncertain indications (Gibbons et 3310

al., 2008). Four inappropriate indications accounted for 88% of inappropriate studies. 3311

The most common inappropriate indication was stress testing in an asymptomatic low-3312

risk patient. 3313

(148) Pre-test classification of patients by indication, with a requirement for specific 3314

justification for patients with no identified appropriate indication, offers an approach to 3315

decrease the number of nuclear stress tests performed that are not justified. The 3316

Commission encourages the development and validation of national and regional 3317

appropriateness criteria for utilization of cardiac imaging. For clinical scenarios in which 3318

more than one imaging modality might be used, appropriateness criteria should 3319

simultaneously address these multiple modalities. (ACR, 2010). Alternative techniques 3320

(such as stress-echocardiography) are available, and should be considered whenever 3321

possible. 3322

3323

7.7.2 Optimization 3324

3325 (149) Several methods can be used to control patient dose in nuclear cardiology. 3326

These include choosing the most appropriate radiopharmaceutical(s), optimizing injected 3327

activity, avoiding rest imaging when stress imaging is normal and encouraging hydration 3328

and early micturition after radiopharmaceutical administration. Hydration and early 3329

micturition may halve the dose to the bladder wall (Einstein et al., 2007). 3330

(150) The choice of protocols is particularly critical. As illustrated in Table 2 and 3331

Figure 1, a variety of standard protocols are available for the performance of myocardial 3332

perfusion imaging. Their effective doses can range from 2 mSv to nearly 30 mSv. The 3333

lowest dose myocardial perfusion imaging protocols use N-13 ammonia. N-13 ammonia 3334

is a PET tracer that requires an on-site cyclotron due to its 10-minute half-life. This 3335

limits its availability. 3336

(151) SPECT protocols may require one or two injections of a radiopharmaceutical. 3337

The radiopharmaceutical may be Tl-201, a Tc-99m-based agent (sestamibi or 3338

tetrofosmin), or both. The effective dose depends on the radiopharmaceutical(s) and 3339


89

injected activities selected. In general, Tc-99m is preferable to Tl-201 on dosimetric 3340

grounds. Effective doses are typically considerably higher for protocols using Tl-201, 3341

and lowest for stress-only Tc-99m protocols. A protocol employing Tl-201 may be 3342

optimal for some patients, e.g. those with a history of Tc-99m images obscured by 3343

increased sub-diaphragmatic tracer uptake, if an alternative imaging modality is not used. 3344

For patients with a low- or low-intermediate pre-test probability of a perfusion defect, in 3345

whom it is expected that stress imaging will be normal, a stress-first/stress-only protocol 3346

is recommended, since rest imaging can be omitted if stress images are normal (Hesse et 3347

al., 2005; Mahmarian, 2010). This approach may be especially useful in conjunction with 3348

attenuation correction, which decreases the percentage of studies with perfusion defects 3349

due to artefact (Gibson et al., 2002). 3350

(152) The Commission recommends formal training in radiological protection, and in 3351

particular in the application of methods to minimize patient dose in accordance with 3352

ALARA principles, for all physicians involved in nuclear cardiology studies, regardless 3353

of their medical specialty. The recommended training is described in ICRP Publication 3354

113 (ICRP, 2009). Additional recommendations are available from the IAEA (IAEA, 3355

2001). 3356

3357

7.7.3 Diagnostic Reference Levels in Nuclear Cardiology 3358

3359 (153) Diagnostic reference levels are used in medical imaging to indicate whether, in 3360

routine conditions, the levels of patient dose from, or administered activity for, a 3361

specified imaging procedure are unusually high or low for that procedure (ICRP, 2007a). 3362

They are discussed further in Chapter 10. If so, a local review should be initiated to 3363

determine whether protection has been adequately optimised or whether corrective action 3364

is required. 3365

(154) Professional medical bodies (in conjunction with national health and 3366

radiological protection authorities) are encouraged to set diagnostic reference levels that 3367

best meet their specific needs and that are consistent for the regional, national, or local 3368

area to which they apply (ICRP, 2007b). In nuclear medicine, reference levels usually 3369

have been derived from pragmatic values of administered activity based on accepted 3370

custom and practice (ICRP, 2007b). Sources of diagnostic reference levels for nuclear 3371

cardiology include ASNC, ECNC, and national guidelines, which provide a range of 3372

administered activities for each protocol. The activity administered to a given patient can 3373

be adjusted within these ranges to reflect patient habitus. For example, while up to 1332 3374

MBq of technetium-99m is recommended per injection in a two-day protocol, this upper 3375

limit should be restricted to larger patients. 3376

3377

7.8 Advice to patients 3378

3379 (155) In recent years, the threat of nuclear terrorism has led to the widespread use of 3380

radiation detectors for security screening at airports and other public facilities. Patients 3381

who have received radiopharmaceuticals for nuclear cardiology studies may retain 3382

sufficient activity to trigger these detectors (Dauer, 2007b). In particular, patients who 3383


90

have received Tl-201 may trigger these detectors for up to 51 days following the 3384

procedure (Dauer, 2007a). Patients should be advised of this possibility and should be 3385

given information cards that indicate the potential time for triggering security radiation 3386

detectors after diagnostic cardiac procedures involving the use of Tl-201 or other 3387

radiopharmaceuticals (Dauer, 2007a) 3388

3389

7.9 Current research areas 3390

3391 (156) Recent technological developments in nuclear cardiology, such as more 3392

sophisticated noise-reducing image reconstruction algorithms and new camera designs 3393

that employ arrays of solid-state detectors, offer the possibility to improve camera 3394

efficiency. Research efforts using these technologies have largely focused on decreasing 3395

acquisition time and improving image quality. These technologies also offer the potential 3396

to markedly decrease administered activity and thereby patient dose, while maintaining 3397

comparable diagnostic performance in comparison to conventional scanners. Further 3398

investigation and clinical validation is required (Patton et al., 2007). 3399

3400

7.10 References 3401

3402

ACR, 2010. American College of Radiology ACR Appropriateness Criteria®. Clinical 3403

Condition: Chronic Chest Pain — High Probability of Coronary Artery Disease. 3404

Available at: 3405

http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx3406


Dauer LT, Williamson MJ, St. Germain J, Strauss HW, 2007a. Tl-201 stress tests and 3408

homeland security. J Nucl Cardiol 14(4):582-588. 3409

Dauer LT, Williamson MJ, St. Germain J, Strauss HW, 2007b. Nuclear granny—reply. 3410

J Nucl Cardiol 14(6):904-905. 3411

Davis W. Mapping improvements in molecular imaging. Medical Imaging. 2006;May 3412

2006. Available at: http://www.imagingeconomics.com/issues/articles/MI_2006-3413

05_01.asp Accessed December 31, 2010. 3414

DePuey, E.G., 2006. Imaging guidelines for nuclear cardiology procedures. 13, e21. 3415

Earls, J.P., Berman, E.L., Urban, B.A., Curry, C.A., Lane, J.L., Jennings, R.S., 3416

McCulloch, C.C., Hsieh, J., Londt, J.H., 2008. Prospectively gated transverse 3417

coronary CT angiography versus retrospectively gated helical technique: improved 3418

image quality and reduced radiation dose. Radiology 246, 742-753. 3419

Earls, J.P., Schrack, E.C., 2008. Prospectively gated low-dose CCTA: 24 months 3420

experience in more than 2,000 clinical cases. Int J Cardiovasc Imaging. 3421

Einstein, A.J., Moser, K.W., Thompson, R.C., Cerqueira, M.D., Henzlova, M.J., 2007. 3422

Radiation dose to patients from cardiac diagnostic imaging. Circulation 116, 1290-3423

1305. 3424

Gerber, T.C., Carr, J.J., Arai, A.E., Dixon, R.L., Ferrari, V.A., Gomes, A.S., Heller, 3425

G.V., McCollough, C.H., McNitt-Gray, M.F., Mettler, F.A., Mieres, J.H., Morin, 3426

R.L., Yester, M.V., 2009. Ionizing Radiation in Cardiac Imaging. A Science 3427






91

Advisory from the American Heart Association Committee on Cardiac Imaging of 3428

the Council on Clinical Cardiology and Committee on Cardiovascular Imaging and 3429

Intervention of the Council on Cardiovascular Radiology and Intervention. 3430

Circulation 119, 1056-1065. 3431

Gibbons, R.J., Miller, T.D., Hodge, D., Urban, L., Araoz, P.A., Pellikka, P., McCully, 3432

R.B., 2008. Application of appropriateness criteria to stress single-photon emission 3433

computed tomography sestamibi studies and stress echocardiograms in an academic 3434

medical center. J Am Coll Cardiol 51, 1283-1289. 3435

Gibson, P.B., Demus, D., Noto, R., Hudson, W., Johnson, L.L., 2002. Low event rate for 3436

stress-only perfusion imaging in patients evaluated for chest pain. J Am Coll Cardiol 3437

39, 999-1004. 3438

Gutstein, A., Wolak, A., Lee, C., Dey, D., Ohba, M., Suzuki, Y., Cheng, V., Gransar, H., 3439

Suzuki, S., Friedman, J., Thomson, L.E., Hayes, S., Pimentel, R., Paz, W., Slomka, 3440

P., Berman, D.S., 2008. Predicting success of prospective and retrospective gating 3441

with dual-source coronary computed tomography angiography: development of 3442

selection criteria and initial experience. Journal of Cardiovascular Computed 3443

Tomography 2, 81-90. 3444

Henzlova, M.J., Cerqueira, M.D., Hansen, C.L., Taillefer, R., Yao, S.-S., 2009. ASNC 3445

imaging guidelines for nuclear cardiology procedures. Stress prorocols and tracers. 3446

Available at: 3447

http://www.asnc.org/imageuploads/ImagingGuidelinesStressProtocols021109.pdf 3448

Accessed January 2, 2011, 3449

Hesse, B., Tagil, K., Cuocolo, A., Anagnostopoulos, C., Bardies, M., Bax, J., Bengel, F., 3450

Busemann Sokole, E., Davies, G., Dondi, M., Edenbrandt, L., Franken, P., Kjaer, A., 3451

Knuuti, J., Lassmann, M., Ljungberg, M., Marcassa, C., Marie, P.Y., McKiddie, F., 3452

O'Connor, M., Prvulovich, E., Underwood, R., van Eck-Smit, B., 2005. EANM/ESC 3453

procedural guidelines for myocardial perfusion imaging in nuclear cardiology. Eur J 3454

Nucl Med Mol Imaging 32, 855-897. 3455

Hunter, C., Ziadi, M., Etele, J., Hill, J., Beanlands, R., deKemp, R., 2010. New effective 3456

dose estimates for Rubidium-82 based on dynamic PET/CT imaging in humans. J 3457

Nucl Med. 2010; 51(Suppl 2):1429. Available at: 3458

http://jnumedmtg.snmjournals.org/cgi/content/meeting_abstract/51/2_MeetingAbstra3459

cts/1429 Accessed January 2, 2011. 3460

Husmann, L., Valenta, I., Gaemperli, O., Adda, O., Treyer, V., Wyss, C.A., Veit-3461

Haibach, P., Tatsugami, F., von Schulthess, G.K., Kaufmann, P.A., 2008. Feasibility 3462

of low-dose coronary CT angiography: first experience with prospective ECG-3463

gating. Eur Heart J 29, 191-197. 3464

IAEA, 2001. Training in radiation protection and the safe use of radiation sources. 3465

Safety Report Series No. 20. Vienna: International Atomic Energy Agency, 2001. 3466


Protection. ICRP publication 26. Ann ICRP 1(3), 1-53. 3468

ICRP, 1979. ICRP publication 30: limits for intakes of radionuclides by workers. Ann 3469

ICRP 2, 1-116. 3470

http://www.asnc.org/imageuploads/ImagingGuidelinesStressProtocols021109.pdf

http://jnumedmtg.snmjournals.org/cgi/content/meeting_abstract/51/2_MeetingAbstracts/1429

http://jnumedmtg.snmjournals.org/cgi/content/meeting_abstract/51/2_MeetingAbstracts/1429


92

ICRP, 1987. Radiation dose to patients from radiopharmaceuticals. A report of a Task 3471

Group of Committee 2 of the International Commission on Radiological Protection. 3472

ICRP Publication 53. Ann.ICRP 18, 1-29. 3473

ICRP, 1998. Radiation dose to patients from radiopharmaceuticals (addendum 2 to ICRP 3474

publication 53). ICRP Publication 80. Ann.ICRP 28, 1-123. 3475

ICRP, 2001. Radiation dose to patients from radiopharmaceuticals. A report of a Task 3476

Group of Committees 2 and 3 of the International Commission on Radiological 3477

Protection. Addendum 5 to ICRP Publication 53. 3478

ICRP, 2007a. The 2007 recommendations of the International Commission on 3479

Radiological Protection. ICRP Publication 103. Ann.ICRP 37, 1-332. 3480

ICRP, 2007b. Radiological Protection in Medicine. ICRP Publication 105. Ann.ICRP 3481

37(6), 1-64. 3482

ICRP, 2008. Radiation dose to patients from radiopharmaceuticals. Addendum 3 to 3483

ICRP Publication 53. ICRP Publication 106. Approved by the Commission in 3484

October 2007. Ann ICRP 38, 1-197. 3485

ICRP, 2009. Radiological protection education and training for healthcare staff and 3486

students (diagnostic imaging and interventional procedures). ICRP Publication 113. 3487

Ann ICRP 39 (5). 3488

Loevinger, R., Budinger, T., Watson, E., 1988. MIRD primer for absorbed dose 3489

calculations. Society of Nuclear Medicine, New York. 3490

Mahmarian, J.J., 2010. Stress only myocardial perfusion imaging: Is it time for a 3491

change? J Nucl Cardiol 17, 529-535. 3492

National Council on Radiation Protection and Measurements. Ionizing radiation 3493

exposure of the population of the United States. NCRP Report No. 160. Bethesda, 3494

MD: National Council on Radiation Protection and Measurements; 2009. 3495

Patton, J.A., Slomka, P.J., Germano, G., Berman, D.S., 2007. Recent technologic 3496

advances in nuclear cardiology. J Nucl Cardiol 14, 501-513. 3497

Roedler, H.D., 1981. Accuracy of internal dose calculations with special consideration of 3498

radiopharmaceutical biokinetics, Third International Radiopharmaceutical Dosimetry 3499

Symposium, HHS Publication FDA 81-8166. Department of Health and Human 3500

Welfare, Bureau of Radiological Health, Rockville, MD. 3501

Rybicki, F.J., Otero, H.J., Steigner, M.L., Vorobiof, G., Nallamshetty, L., Mitsouras, D., 3502

Ersoy, H., Mather, R.T., Judy, P.F., Cai, T., Coyner, K., Schultz, K., Whitmore, 3503

A.G., Di Carli, M.F., 2008. Initial evaluation of coronary images from 320-detector 3504

row computed tomography. Int J Cardiovasc Imaging 24, 535-546. 3505

Senthamizhchelvan, S., Bravo, P.E., Esaias, C., Lodge, M.A., Merrill, J., Hobbs, R.F., 3506

Sgouros, G., Bengel, F.M., 2010. Human biodistribution and radiation dosimetry of 3507 82

Rb. J. Nucl. Med. 51, 1592-1599. 3508

Stabin, M., 2006. Nuclear medicine dosimetry. Phys Med Biol 51, R187-202. 3509

Stabin, M., Siegel, J., Hunt, J., Sparks, R., Lipsztein, J., Eckerman, K., 2001. RADAR: 3510

the radiation dose assessment resource—an online source of dose information for 3511

nuclear medicine and occupational radiation safety [abstract]. J Nucl Med 42(suppl), 3512

243P. 3513


93

Stabin, M.G., 2008a. Radiopharmaceuticals for nuclear cardiology: radiation dosimetry, 3514

uncertainties, and risk. J Nucl Med 49, 1555-1563. 3515

Stabin, M.G., 2008b. Uncertainties in internal dose calculations for 3516

radiopharmaceuticals. J Nucl Med 49, 853-860. 3517

Stabin, M.G., 2010. Proposed revision to the radiation dosimetry of 82Rb. Health Phys. 3518

99, 811-813. 3519

UNSCEAR. Sources and effects of ionizing radiation: volume I, sources: annex D, 3520

medical radiation exposure. Report to the General Assembly of the United Nations; 3521

2000; New York, NY Available at: 3522

http://www.unscear.org/unscear/en/publications/2000_1.html Accessed December 3523

31, 2010. 3524

3525

3526



94

8. RADIOLOGICAL PROTECTION FOR CARDIAC CT 3527

3528

Main Points 3529

Appropriate use criteria and guidelines for justification have been developed 3530

through consensus efforts of professional societies. 3531

Justification needs to be performed on an individualized, patient-by-patient 3532

basis, weighing the benefits and risks of each imaging test under 3533

consideration as well as of doing no test. Assessment of radiation risk is one 3534

part of this process. 3535

Dose from cardiac CT is strongly dependent on scanner mode, tube current, 3536

and tube voltage. 3537

For patients with a heart rate less than 65-70 bpm and a regular rhythm, 3538

diagnostic image quality can generally be maintained while using dose-3539

reduction methods such as ECG-controlled tube current modulation and 3540

axial imaging. The maximum tube current should be appropriate for the 3541

patient’s habitus. 3542

Further research is needed to develop and validate methods, such as newer 3543

scan modes and low-voltage scanning, to minimize radiation dose to patients 3544

and practitioners. 3545 3546


3548 (157) The possibility of CT of the coronary arteries was suggested by Sir Godfrey 3549

Hounsfield, inventor of the CT scanner, in his 1979 Nobel Lecture when he stated ―A 3550

further promising field may be the detection of the coronary arteries. It may be possible 3551

to detect these under special conditions of scanning.‖ (Hounsfield, 1979). Unlike nuclear 3552

cardiology technology, which has remained largely static, cardiac CT technology has 3553

evolved rapidly in recent years. These advancements have enabled a variety of types of 3554

cardiac CT studies to be performed. Today, cardiac CT encompasses several distinct 3555

procedures, including coronary artery calcium (CAC) scoring, CT coronary angiography 3556

(CTCA), pulmonary vein CT angiography, and CT attenuation correction of nuclear 3557

cardiology image data. Recent technological advances have been associated with an 3558

increase in the number of procedures performed, although reliable statistics on worldwide 3559

numbers are not available at present. 3560

3561

8.2 Types of CT scanners 3562

3563 (158) Each new generation of CT scanners has varied from its predecessors in terms 3564

of technical parameters (e.g., temporal resolution, spatial resolution, craniocaudal 3565

coverage) and also in patent radiation dose. The first scanner capable of performing 3566

cardiac studies, the dynamic spatial reconstructor, used 14 x-ray sources that rotated 3567

around the patient, resulting in patient doses approaching 100 Gy (Block et al., 1984). 3568

The electron beam CT scanner, also called ―ultrafast‖ CT due to its excellent temporal 3569

resolution, superseded this machine. Patient dose from electron beam CT was markedly 3570


95

lower, with typical effective doses of approximately 1 mSv for both CAC scoring and 3571

CTCA (Morin et al., 2003). Electron beam CT scanners had low spatial resolution, and 3572

have been supplanted by multiple-detector-row CT (MDCT) scanners. The improved 3573

spatial resolution of MDCT scanners enables a more accurate assessment of coronary 3574

stenosis and plaque visualization. Initial efforts at CTCA were performed with 4-slice 3575

scanners. The technology gained popularity with subsequent generations of faster 16- 3576

and 64-slice scanners and became even more widespread with the advent of 128- and 3577

256-slice scanners. MDCT is the focus of ICRP Publication 102 (ICRP, 2007a). 3578

3579

8.3 Dosimetric Quantities 3580

3581 (159) Currently, three types of dosimetric quantities are utilized for CT. These are: i) 3582

weighted CT dose index (CTDIw) and volume CT dose index (CTDIvol), ii) dose-length 3583

product (DLP), and iii) effective dose. CTDIw and CTDIvol are estimates of the average 3584

dose within the central portion of the scan volume. DLP integrates the CTDIvol over the 3585

length of the anatomy scanned, and reflects the increased patient dose when a longer 3586

portion of the patient is scanned (e.g., chest vs. heart). Effective dose is a calculated 3587

quantity used to reflect the risk of a radiation exposure to a portion of the body in terms 3588

of a uniform whole-body exposure. Effective dose was developed as a radiological 3589

protection quantity, and is used to compare radiation risk among different diagnostic 3590

examinations (ICRP, 2007b; McCollough, 2008) 3591

(160) Current MDCT scanners typically report CTDIvol and DLP for each study. 3592

Effective dose can be estimated by multiplying DLP by a body-region-specific 3593

conversion factor (k factor). For cardiac studies, the most commonly used conversion 3594

factor is of 0.017 mSv·mGy-1

·cm-1

, the European Guidelines on Quality Criteria for 3595

Computed Tomography chest factor (i.e., effective dose is estimated as 0.017·DLP) 3596

(Bongartz et al., 2000). This conversion factor does not reflect the more recent ICRP 3597

Publication 103 tissue weighting factors, is derived from data from single-slice scanners, 3598

and was developed for chest scans rather than cardiac scans (Christner et al., 2010; 3599

Einstein et al., 2010). This method provides a useful approximation of effective dose 3600

from cardiac CT based on easily available data, but it typically underestimates effective 3601

dose. Alternative, more complex approaches for determining effective dose are Monte 3602

Carlo simulations and determination of organ doses in physical anthropomorphic 3603

phantoms. These are discussed in more detail in ICRP Publication 102 (ICRP, 2007a). 3604

3605

8.4 Factors affecting patient dose 3606

3607 (161) Factors affecting patient dose in cardiac CT include both those intrinsic to the 3608

scanner, such as scanner generation, model and manufacturer, and parameters selected by 3609

the operator. Hausleiter et al, in an observational study of 50 sites performing CTCA, 3610

observed a marked difference between scanner manufacturers in effective dose 3611

(Hausleiter et al., 2009). Reported doses from CTCA vary depending on which 3612

generation of MDCT scanners was used (Einstein et al., 2007). The most recent 3613

generation of scanners incorporates technology with the potential to decrease patient 3614


96

doses considerably. Operator-selectable parameters that affect dose include x-ray tube 3615

current (mA) or tube current-time product (mAs), tube peak voltage (kVp), pitch (IEC, 3616

2009), scan length (craniocaudal coverage), scan mode, and in some cases the number of 3617

x-ray tubes employed. 3618

3619

8.4.1 Tube Current 3620

3621 (162) The choice of an appropriate mA and kVp for a given study reflects a trade-off 3622

between image noise and radiation dose. Increasing the tube current results in both a 3623

decrease in image noise and an increase in radiation dose. Dose increases in a roughly 3624

linear fashion with increased tube current (Gerber et al., 2005). Baseline tube current 3625

should be adjusted to reflect patient habitus, as larger patients will require a higher tube 3626

current to obtain images with standard levels of noise. For the same tube current, 3627

different scanners will produce images with different amounts of noise, so protocols must 3628

be tailored to each scanner. A sensible balance is required—overly aggressive reductions 3629

in radiation dose may render the scan non-diagnostic. New image reconstruction 3630

algorithms incorporating an iterative noise-reduction methodology may maintain image 3631

quality while decreasing tube current. 3632

3633

8.4.2 Tube Voltage 3634

3635 (163) For cardiac MDCT applications, a tube voltage of 120 kVp is common. For 3636

smaller patients, a lower voltage, e.g. 100 kVp, is used in some centres. Dose varies 3637

approximately with voltage to the 2.5 power, so a 37% dose reduction would be expected 3638

with this decrease in tube voltage. The evidence supporting low-voltage CTCA (Abada 3639

et al., 2006; Bischoff et al., 2009; Hausleiter et al., 2010) is not as robust as that 3640

supporting 120 kVp CTCA (Abdulla et al., 2007). However, many sites have obtained 3641

excellent image quality using reduced voltage (Figure 8.1). 3642

3643


97

3644 Figure 8.1. CT coronary angiogram, obtained using a tube voltage of 100 kVp and 3645

single-heartbeat volume scanning. Courtesy Andrew J. Einstein, MD, PhD, Columbia 3646

University Medical Centre, New York, NY, USA 3647

3648

8.4.3 Scan Length 3649

3650 (164) Patient dose is linearly related to the length of the portion of the body 3651

irradiated, which is basically equal to the scan length. Typically CTCA is performed 3652

with scanning from the carina to the base of the heart, with a small margin of error on 3653

each side to allow for patient motion. A scan length of 11-15 cm is typical. Excessively 3654

large margins result in increased patient dose without additional diagnostic information. 3655

Greater craniocaudal coverage is necessary when the aorta must be included and in cases 3656

where the patient has undergone coronary artery bypass grafting, in which case the upper 3657

limit of the scan is above the aortic arch. For pulmonary vein CT angiography, the scan 3658

length can be reduced. In this case the structures of interest are the left atrium, 3659

pulmonary veins, and their anatomic relationship to the oesophagus and aorta; these can 3660

be visualized without scanning caudally to the cardiac apex. 3661

3662

8.4.4 Scan Mode 3663

3664


98

(165) Scan modes include conventional helical (spiral) imaging with constant tube 3665

current, conventional helical imaging with ECG-gated tube current modulation 3666

(EGTCM), high-pitch helical imaging and axial imaging, including both step-and-shoot 3667

and volume imaging (Figure 8.2). CTCA using MDCT was first performed using helical 3668

mode and a constant tube current, with a typical pitch of 0.2 for 64-slice scanners 3669

(Figure. 8.2 (a)). All current cardiac scanners offer EGTCM, which keeps tube current 3670

at its maximum during diastasis, when coronary movement is generally minimized, and 3671

decreases tube current during the remainder of the cardiac cycle (Figure 8.2 (b)). This 3672

limits the number of phases of the cardiac cycle in which image reconstructions can be 3673

performed without excessive noise, but for patients with low heart rates (<65 bpm) and 3674

regular heart rhythms, this generally does not pose a problem. Generally, patients should 3675

receive beta blockers or calcium channel blockers to lower heart rate and improve the 3676

efficacy of EGTCM. For patients who do not meet these conditions, reconstructions at 3677

end-systole are often quite useful for visualizing the proximal- and mid-right coronary 3678

artery (Sanz et al., 2005). If EGTCM is applied in these patients, it may be advisable to 3679

widen the period of time during which tube current is maintained at its maximal value. 3680

EGTCM typically decreases effective dose by about one-third. For single-source 3681

scanners, this decrease in dose is more pronounced with lower heart rates (Jakobs et al., 3682

2002). 3683

(166) More recently, axial CTCA protocols have been incorporated into some MDCT 3684

scanners. This approach to scanning acquires image data only during a pre-specified 3685

phase of the cardiac cycle, and the x-ray beam is off during the remainder of the cardiac 3686

cycle. In step-and-shoot (sequential) scanning, x-rays are delivered in one cardiac cycle, 3687

the patient couch is advanced with the beam off during the next cardiac cycle, and the 3688

process is repeated until the entire craniocaudal volume of interest has been scanned. For 3689

64-detector-row scanners, this generally requires 3 or 4 iterations, i.e. 5 or 7 heartbeats (5 3690

heartbeats illustrated in Figure 8.2 (c)). For step-and-shoot imaging to generate 3691

interpretable cardiac images, it is generally thought that heart rate should be less than 70 3692

beats per minute and heart rhythm should be regular, although this has not been well 3693

studied. An advantage of step-and-shoot imaging is reduced dose due to the elimination 3694

of radiation exposure during much of the cardiac cycle and the absence of the overlap of 3695

irradiated areas characteristic of helical CTCA. Disadvantages include the inability to 3696

retrospectively perform image reconstruction at additional phases of the cardiac cycle and 3697

the attendant inability to assess cardiac function and wall motion. 3698

(167) One modification of axial imaging is to increase the length of time that the x-3699

ray tube is on, thus increasing dose but enabling reconstructions within a range of phases 3700

of the cardiac cycle (Figure 8.2 (d)). Thus, rather than obtaining only images in a single 3701

portion of diastasis, a variety of strategies can be employed, such as obtaining images in a 3702

range of diastolic phases, or covering from end-systole through diastasis. Dose is 3703

proportional to exposure time. The optimal strategy for implementation of axial imaging 3704

has not yet been determined. 3705

(168) Two recently-introduced scan modes offer the potential for significant dose 3706

reductions. Both cover the entire heart with x-rays delivered for only a fraction of a 3707

single heartbeat (Figure 8.2 (e)). The extreme case of axial imaging is volume scanning, 3708


99

which uses a cone-beam x-ray source and a large detector array that covers the entire 3709

heart without requiring table motion (Einstein et al., 2010). The extreme case of helical 3710

imaging is high-pitch helical scanning, in which two x-ray sources mounted at 90° from 3711

each other are used with a rapid table speed to enable the entire heart to be covered in a 3712

fraction of a beat.(Achenbach et al., 2010) Each of these modes currently requires a low 3713

heart rate to obtain excellent image quality at minimal radiation dose. 3714

(169) The clinical literature evaluating axial CTCA and the single-heartbeat modes is 3715

limited (Earls et al., 2008; Gutstein et al., 2008; Husmann et al., 2008; Rybicki et al., 3716

2008). There are no multicentre studies evaluating diagnostic accuracy efficacy in 3717

comparison to gold-standard diagnosis by invasive angiography. These scan modes 3718

require more rigorous validation. 3719

3720

Figure 8.2 3721

3722 Scan modes used in cardiac CT. Black line denotes electrocardiographic signal, shaded 3723

region represents tube current. (a) helical scan, (b) helical scan with 3724


100

electrocardiographically-gated tube current modulation, (c) axial step-and-shoot scan, (d) 3725

axial step-and-shoot scan, with extending exposure time (―padding‖) to permit 3726

reconstruction of multiple cardiac phases, (e) axial single heartbeat scan (volume and 3727

high-pitch helical scans, illustrated here with no padding). Not all modes are available on 3728

all MDCT scanners. 3729

3730

8.5 Current Dosimetry Estimates 3731

3732 (170) Dosimetry from CTCA depends on many factors, and thus varies markedly 3733

between protocols. Einstein et al reviewed the published literature on effective dose from 3734

cardiac CT in 2007(Einstein et al., 2007). Effective doses from calcium scoring ranged 3735

from 1.0 to 6.2 mSv using helical technique and from 0.5 to 1.8 mSv using axial 3736

technique. For helical 64-slice CTCA, effective dose ranged from 8 to 21.4 mSv without 3737

and from 6.4 to 14 mSv with EGTCM. In a 15 centre study performed in the U.S., 3738

median effective dose, estimated using a k factor of 0.014 mSv·mGy-1

·cm-1

, was 21 mSv 3739

prior to a best-practice dose reduction educational intervention (Raff et al., 2009). In a 3740

50-centre worldwide study, median effective dose was 12 mSv (Hausleiter et al., 2009). 3741

In Hausleiter et al‘s study, there was a 6-fold range in median doses among sites 3742

performing CTCA. EGTCM was associated with a reduction in dose-length product and 3743

effective dose of 25% (95% confidence interval 23-28%), use of an x-ray tube voltage of 3744

100 kV was associated with a reduction of 46% (95% confidence interval 42-51%), and 3745

use of axial step-and-shoot scanning was associated with a reduction of 78% (95% 3746

confidence interval 77-79%) (Hausleiter et al., 2009). Other single-centre studies have 3747

evaluated axial step-and-shoot scanning, and typically report effective doses in the 2-4 3748

mSv range (Earls and Schrack, 2008). In comparison to conventional helical scanning, 3749

volume scanning has been associated with a dose reduction of 84%, (Einstein et al., 3750

2010), and high-pitch helical scanning has been associated with effective dose of <1 mSv 3751

for patients with a slow (≤60 bpm) heart rate who weigh ≤100 kg (Achenbach et al., 3752

2010), using a k factor of 0.014 mSv·mGy-1

·cm-1

. 3753

(171) The wide range of values for effective dose seen in clinical practice makes it 3754

impossible to provide ―typical‖ values for cardiac CT. Effective dose is dependent on 3755

both the CT scanner and the protocol used. Estimates of approximate average values are 3756

presented in Table 8.1, but it must be appreciated that these values should not be 3757

considered as typical values, target values, or representative of clinical practice at any 3758

one institution. 3759

3760

3761

3762

3763

3764

3765

3766

3767

3768


101

Table 8.1 Estimated Approximate Average Effective Dose for Various Types of Cardiac 3769

CT Examinations 3770

3771

Examination Effective Dose (mSv)* 3772

3773

CT coronary angiography (CTCA) (helical) 19 3774

3775

CT coronary angiography (CTCA) (tube current modulation) 13 3776

3777

CT coronary angiography (CTCA) (prospectively gated) 4 3778

3779

Coronary artery calcium scoring (CAC) 2 3780

3781

*The data in the Table are reproduced from Einstein, 2009. For other estimates of 3782

effective dose, see, e.g., Einstein et al, 2007; Hausleiter et al, 2009; Kim et al, 2009; 3783

Smith-Bindman et al, 2009; Earls and Schrack, 2009; Raff et al, 2009. 3784

3785

3786

3787

(172) Effective doses reported in many of the studies assessing CT protocols are 3788

determined on a patient-by-patient basis. The existence of conversion factors, such as 3789

those in the European Guidelines on Quality Criteria for CT (Bongartz et al., 2000; 3790

Bongartz et al.), make it easy for an investigator to estimate an ―effective dose‖ for a 3791

single study from the DLP reported on the scanner, but this is not the intended use of 3792

effective dose (Einstein et al., 2008; Gerber et al., 2009; ICRP 2007b). Citation of these 3793

studies is not an endorsement of this approach by the Commission. When the 3794

Commission introduced effective dose in 1990 (ICRP, 1991), it was defined for 3795

populations, not for specific individuals. This has not changed. 3796

3797

8.6 Radiological Protection of Patients in Cardiac CT 3798

3799 (173) The general principles of radiological protection (chapter 4), i.e., justification 3800

and optimisation, can be applied to the protection of patients in cardiac CT. Dose 3801

limitation is not appropriate, but diagnostic reference levels should be used to help 3802

manage the radiation dose so that the dose is commensurate with the clinical purpose 3803

(ICRP, 2007b, ICRP, 2007c). 3804

3805

8.6.1 Justification 3806

3807 (174) The Commission recommends the development and application of appropriate 3808

use criteria for cardiac CT. Appropriate indications for cardiac CT are available from 3809

professional organizations and should be used (Taylor et al, 2010; Schroeder et al., 2008). 3810

3811


102

(175) In reports from one institution, 46% of CTCA studies but only 11% of stress 3812

SPECT studies were unclassifiable in terms of appropriateness, and of the remaining 3813

classifiable studies, 51% of CTCA studies and 72% of stress SPECT studies were 3814

appropriate.(Gibbons et al., 2008; Miller et al.) It is unclear from these data whether the 3815

difference between modalities primarily reflects a limitation with the first version of the 3816

U.S. CTCA appropriateness criteria, which left many studies unclassifiable, or whether 3817

CTCA studies are less likely to be performed for appropriate indications that SPECT 3818

studies. Further investigation is required, and programs to ensure maximal adherence to 3819

appropriate use criteria are also encouraged. 3820

3821

8.6.2 Optimization 3822

3823 (176) As discussed in section 8.3, the operator controls numerous scan parameters 3824

that affect patient dose. The operator should be provided with appropriate guidelines for 3825

mAs and kVp selection as a function of patient body habitus. Special consideration 3826

should be given to reducing mAs and/or kVp when evaluation of coronary plaques and 3827

stenoses is not the primary aim, e.g. for evaluation of possible anomalous coronaries, or 3828

prior to repeat cardiac surgery to assess the course of bypass grafts in relation to the 3829

sternum. Scan length should be limited to that needed to reliably image the volume of 3830

interest. 3831

(177) The operator should be provided with appropriate guidelines for selection of 3832

the scan mode. Scan modes that reduce dose should be employed as appropriate (Gerber 3833

et al., 2009). Scans performed for calcium scoring should be performed using axial 3834

imaging, and in combined studies should be reviewed prior to performance of CTCA. 3835

The presence of widespread, heavy coronary calcification may suggest that CTCA should 3836

not be performed, due to the high likelihood of unevaluable coronary segments. For all 3837

patients, with the possible exception of patients scanned on a multiple-source scanner 3838

with variable pitch, rate-control agents should be given as needed with the goal of 3839

decreasing heart rate to approximately 60 beats per minute. 3840

(178) The Commission recommends formal training in radiological protection, and in 3841

particular in the application of the principles of justification and optimization, for all 3842

physicians who refer patients for, or perform, cardiac CT studies (ICRP 113, 2011). This 3843

includes cardiologists, radiologists, nuclear medicine specialists, and internists. 3844

(179) Quality improvement programs have been shown to decrease radiation dose 3845

substantially for CTCA (Raff et al., 2009), and thus their implementation is encouraged. 3846

3847

8.6.3 Diagnostic Reference Levels 3848

3849 (180) Diagnostic reference levels are used in medical imaging to indicate whether, in 3850

routine conditions, the levels of patient dose from, or administered activity for, a 3851

specified imaging procedure are unusually high or low for that procedure (ICRP, 2007b). 3852

They are discussed further in Chapter 10. If so, a local review should be initiated to 3853

determine whether protection has been adequately optimised or whether corrective action 3854

is required. 3855


103

(181) Professional medical bodies (in conjunction with national health and 3856

radiological protection authorities) are encouraged to set diagnostic reference levels that 3857

best meet their specific needs and that are consistent for the regional, national, or local 3858

area to which they apply (ICRP, 2007c). At present, no diagnostic reference levels exist 3859

for cardiac CT. 3860

3861


Abada, H.T., Larchez, C., Daoud, B., Sigal-Cinqualbre, A., Paul, J.F., 2006. MDCT of 3864

the coronary arteries: feasibility of low-dose CT with ECG-pulsed tube current 3865

modulation to reduce radiation dose. AJR Am J Roentgenol 186, S387-390. 3866

Abdulla, J., Abildstrom, S.Z., Gotzsche, O., Christensen, E., Kober, L., Torp-Pedersen, 3867

C., 2007. 64-multislice detector computed tomography coronary angiography as 3868

potential alternative to conventional coronary angiography: a systematic review and 3869

meta-analysis. Eur Heart J 28, 3042-3050. 3870

Achenbach, S., Marwan, M., Ropers, D., Schepis, T., Pflederer, T., Anders, K., Kuettner, 3871

A., Daniel, W.G., Uder, M., Lell, M.M., 2010. Coronary computed tomography 3872

angiography with a consistent dose below 1 mSv using prospectively 3873

electrocardiogram-triggered high-pitch spiral acquisition. Eur Heart J 31, 340-346. 3874

Bischoff, B., Hein, F., Meyer, T., Hadamitzky, M., Martinoff, S., Schomig, A., 3875

Hausleiter, J., 2009. Impact of a reduced tube voltage on CT angiography and 3876

radiation dose: results of the PROTECTION I study. JACC Cardiovasc Imaging 2, 3877

940-946. 3878

Block, M., Bove, A.A., Ritman, E.L., 1984. Coronary angiographic examination with the 3879

dynamic spatial reconstructor. Circulation 70, 209-216. 3880

Bongartz, G., Golding, S.J., Jurik, A.G., Leonardi, M., van Meerten, E.v.P., Geleijns, J., 3881

Jessen, K.A., Panzer, W., Shrimpton, P.C., Tosi, G., 2000. European Guidelines on 3882

Quality Criteria for Computed Tomography. EUR 16262. The European 3883

Commission's Study Group on Development of Quality Criteria for Computed 3884

Tomography. 3885

Bongartz, G., Golding, S.J., Jurik, A.G., Leonardi, M., van Meerten, E.v.P., Rodríguez, 3886

R., Schneider, K., Calzado, A., Geleijns, J., Jessen, K.A., Panzer, W., Shrimpton, 3887

P.C., Tosi, G., 2004 CT Quality Criteria, European Commission. 3888

Christner, J.A., Kofler, J.M., McCollough, C.H., 2010. Estimating effective dose for CT 3889

using dose-length product compared with using organ doses: consequences of 3890

adopting International Commission on Radiological Protection publication 103 or 3891

dual-energy scanning. AJR Am J Roentgenol 194, 881-889. 3892

Earls, J.P., Schrack, E.C., 2009. Prospectively gated low-dose CCTA: 24 months 3893

experience in more than 2,000 clinical cases. Int. J. Cardiovasc. Imaging 25, 177-3894

187. 3895

Einstein, A.J., Elliston, C.D., Arai, A.E., Chen, M.Y., Mather, R., Pearson, G.D.N., 3896

DeLaPaz, R.L., Nickoloff, E., Dutta, A., Brenner, D.J., 2010. Radiation dose from 3897

single heartbeat coronary CT angiography performed using a 320 detector-row 3898

volume scanner. Radiology 254, 698-704. 3899


104

Einstein, A.J., 2009. Medical imaging: the radiation issue. Nat. Rev. Cardiol. 6, 436-438. 3900

Einstein, A.J., Moser, K.W., Thompson, R.C., Cerqueira, M.D., Henzlova, M.J., 2007. 3901

Radiation dose to patients from cardiac diagnostic imaging. Circulation 116, 1290-3902

1305. 3903

Einstein, A.J., Sanz, J., Dellegrottaglie, S., Milite, M., Sirol, M., Henzlova, M., 3904

Rajagopalan, S., 2008. Radiation dose and cancer risk estimates in 16-slice computed 3905

tomography coronary angiography. J Nucl Cardiol 15, 232-240. 3906

Gerber, T.C., Carr, J.J., Arai, A.E., Dixon, R.L., Ferrari, V.A., Gomes, A.S., Heller, 3907

G.V., McCollough, C.H., McNitt-Gray, M.F., Mettler, F.A., Mieres, J.H., Morin, 3908

R.L., Yester, M.V., 2009. Ionizing Radiation in Cardiac Imaging. A Science 3909

Advisory From the American Heart Association Committee on Cardiac Imaging of 3910

the Council on Clinical Cardiology and Committee on Cardiovascular Imaging and 3911

Intervention of the Council on Cardiovascular Radiology and Intervention. 3912

Circulation 119, 1056-1065. 3913

Gerber, T.C., Stratmann, B.P., Kuzo, R.S., Kantor, B., Morin, R.L., 2005. Effect of 3914

acquisition technique on radiation dose and image quality in multidetector row 3915

computed tomography coronary angiography with submillimeter collimation. 3916

Invest.Radiol. 40, 556. 3917

Gibbons, R.J., Miller, T.D., Hodge, D., Urban, L., Araoz, P.A., Pellikka, P., McCully, 3918

R.B., 2008. Application of appropriateness criteria to stress single-photon emission 3919

computed tomography sestamibi studies and stress echocardiograms in an academic 3920

medical center. J Am Coll Cardiol 51, 1283-1289. 3921

Hausleiter, J., Meyer, T., Hadamitzky, M., Huber, E., Zankl, M., Martinoff, S., Kastrati, 3922

A., Schomig, A., 2006. Radiation dose estimates from cardiac multislice computed 3923

tomography in daily practice: impact of different scanning protocols on effective 3924

dose estimates. Circulation 113, 1305. 3925

Hausleiter, J., Meyer, T., Hermann, F., Hadamitzky, M., Krebs, M., Gerber, T.C., 3926

McCollough, C., Martinoff, S., Kastrati, A., Schömig, A., Achenbach, S., 2009. 3927

Estimated radiation dose associated with cardiac CT angiography. JAMA 301, 500-3928

507. 3929

Hausleiter, J., Martinoff, S., Hadamitzky, M., Martuscelli, E., Pschierer, I., Feuchtner, 3930

G.M., Catalan-Sanz, P., Czermak, B., Meyer, T.S., Hein, F., Bischoff, B., Kuse, M., 3931

Schomig, A., Achenbach, S., 2010. Image quality and radiation exposure with a low 3932

tube voltage protocol for coronary CT angiography. Results of the PROTECTION II 3933

Trial. JACC Cardiovasc Imaging 3, 1113-1123. 3934

Hounsfield, G.N., 1979. Computed medical imaging. Nobel lecture, 8 December 1979. 3935

ICRP, 1991. 1990 Recommendations of the International Commission on Radiological 3936

Protection. ICRP Publication 60. Ann. ICRP 21, 1-201. 3937

ICRP, 2007a. Managing patient dose in multi-detector computed tomography (MDCT). 3938

ICRP Publication 102. Ann. ICRP 37(1), 1-79. 3939

ICRP, 2007b. The 2007 recommendations of the International Commission on 3940

Radiological Protection. ICRP Publication 103. Ann. ICRP 37, 1-332. 3941

ICRP, 2007c. Radiological Protection in Medicine. ICRP Publication 105. Ann. ICRP 3942

37(6), 1-64. 3943


105

IEC, 2009. Medical Electrical Equipment - Part 2-44: Particular Requirements for the 3944

Safety of X-ray Equipment for Computed Tomography. International Standard IEC 3945

60601-2-44. 3rd Edition. International Electrotechnical Commission, Geneva. 3946

Jakobs, T.F., Becker, C.R., Ohnesorge, B., Flohr, T., Suess, C., Schoepf, U.J., Reiser, 3947

M.F., 2002. Multislice helical CT of the heart with retrospective ECG gating: 3948

reduction of radiation exposure by ECG-controlled tube current modulation. 3949

Eur.Radiol. 12, 1081. 3950

Kim, K.P., Einstein, A.J., Berrington de Gonzalez, A., 2009. Coronary artery 3951

calcification screening: estimated radiation dose and cancer risk. Arch. Intern. Med. 3952

169, 1188-1194. 3953

McCollough, C.H., 2008. CT dose: how to measure, how to reduce. Health Physics 95, 3954

508-517. 3955

Miller, J.A., Raichlin, E., Williamson, E.E., McCully, R.B., Pellikka, P.A., Hodge, D.O., 3956

Miller, T.D., Gibbons, R.J., Araoz, P.A., 2010. Evaluation of coronary CTA 3957

Appropriateness Criteria in an academic medical center. J Am Coll Radiol 7, 125-3958

131. 3959

Morin, R.L., Gerber, T.C., McCollough, C.H., 2003. Radiation dose in computed 3960

tomography of the heart. Circulation 107, 917. 3961

Raff, G.L., Chinnaiyan, K.M., Share, D.A., Goraya, T.Y., Kazerooni, E.A., Moscucci, 3962

M., Gentry, R.E., Abidov, A., 2009. Radiation dose from cardiac computed 3963

tomography before and after implementation of radiation dose-reduction techniques. 3964

JAMA 301, 2340-2348. 3965

Sanz, J., Rius, T., Kuschnir, P., Fuster, V., Goldberg, J., Ye, X.Y., Wisdom, P., Poon, 3966

M., 2005. The importance of end-systole for optimal reconstruction protocol of 3967

coronary angiography with 16-slice multidetector computed tomography. 3968

Invest.Radiol. 40, 155. 3969

Schroeder, S., Achenbach, S., Bengel, F., Burgstahler, C., Cademartiri, F., de Feyter, P., 3970

George, R., Kaufmann, P., Kopp, A.F., Knuuti, J., Ropers, D., Schuijf, J., Tops, L.F., 3971

Bax, J.J., 2008. Cardiac computed tomography: indications, applications, limitations, 3972

and training requirements: report of a Writing Group deployed by the Working 3973

Group Nuclear Cardiology and Cardiac CT of the European Society of Cardiology 3974

and the European Council of Nuclear Cardiology. Eur Heart J 29, 531-556. 3975

Smith-Bindman, R., Lipson, J., Marcus, R., Kim, K.P., Mahesh, M., Gould, R., 3976

Berrington de Gonzalez, A., Miglioretti, D.L., 2009. Radiation dose associated with 3977

common computed tomography examinations and the associated lifetime attributable 3978

risk of cancer. Arch. Intern. Med. 169, 2078-2086. 3979

Taylor, A.J., Cerqueira, M., Hodgson, J.M., Mark, D., Min, J., O'Gara, P., Rubin, G.D., 3980

Kramer, C.M., Berman, D., Brown, A., Chaudhry, F.A., Cury, R.C., Desai, M.Y., 3981

Einstein, A.J., Gomes, A.S., Harrington, R., Hoffmann, U., Khare, R., Lesser, J., 3982

McGann, C., Rosenberg, A., Schwartz, R., Shelton, M., Smetana, G.W., Smith, S.C., 3983

Jr., 2010. ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 3984

appropriate use criteria for cardiac computed tomography: a report of the American 3985

College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society 3986

of Cardiovascular Computed Tomography, the American College of Radiology, the 3987


106

American Heart Association, the American Society of Echocardiography, the 3988

American Society of Nuclear Cardiology, the North American Society for 3989

Cardiovascular Imaging, the Society for Cardiovascular Angiography and 3990

Interventions, and the Society for Cardiovascular Magnetic Resonance. J. Am. Coll. 3991

Cardiol. 56, 1864-1894. 3992

3993

3994

3995

3996


107

9. RADIOLOGICAL PROTECTION TRAINING FOR 3997

INTERVENTIONAL FLUOROSCOPY 3998

3999

Main Points 4000

Interventional cardiologists worldwide typically have little or no training in 4001

radiological protection (RP). 4002

Legislation in most countries requires that individuals who take 4003

responsibility for medical exposures must be properly trained in RP. 4004

Training activities in RP should be followed by an evaluation of the 4005

knowledge acquired from the training programme (a formal examination 4006

system). 4007

Physicians who have completed training should be able to demonstrate that 4008

they possess the knowledge specified by the curriculum by passing an 4009

appropriate certifying examination. 4010

In addition to the training recommended for other physicians who use X-4011

rays, interventionalists, including interventional cardiologists, should receive 4012

a second, higher level of RP training. 4013

Nurses and other healthcare professionals who assist during fluoroscopic 4014

procedures should be familiar with radiation risks and radiological 4015

protection principles, in order to minimise their own exposure and that of 4016

others. 4017

Training programmes should include both initial training for all incoming 4018

staff and regular updating and retraining. 4019

Scientific congresses should include refresher courses on RP, attendance at 4020

which could be a requirement for continuing professional development 4021

4022


4024

(182) Despite the extensive and routine use of x-rays in their clinical practice, 4025

interventional cardiologists (IC) worldwide typically have little or no training in 4026

radiological protection (RP). Traditionally, medical students do not receive training in RP 4027

during medical school. Medical professionals who subsequently specialise in radiological 4028

specialties, such as diagnostic radiology, nuclear medicine and radiotherapy, are taught 4029

radiological physics and RP as part of their specialty training. In many countries, there is 4030

no teaching of RP during training in other specialties, such as medicine and cardiology. 4031

(183) In the past, training in radiological physics and RP was not necessary for non-4032

radiologists, as x-rays and other radiation sources were employed only in radiology 4033

departments, by staff with reasonable training in RP. Although x-ray fluoroscopy has 4034

been in use for more than a century now, its early application involved visualization of 4035

body anatomy, movement of structures or passage of contrast media through the body. 4036

Radiologists normally performed these procedures. When fluoroscopically guided 4037

interventions were introduced, other specialists (cardiologists and an increasing number 4038


108

of clinicians in other medical specialties) began performing these procedures. Initially, 4039

they did so jointly with radiologists, in radiology departments. Over the years, x-ray 4040

equipment was installed in other clinical departments and used by non-radiologists 4041

without radiologist participation. These non-radiologists were not subject to the training 4042

requirements of radiological physics and RP that were mandatory for radiologists. It is 4043

now clear that this training is essential; hence the need for specific guidance for 4044

cardiology. 4045

(184) The Commission has addressed the specifics of training for interventionalists 4046

and nuclear medicine specialists, among others, in ICRP Publication 113 (ICRP 113, 4047

2009). Further information on training in nuclear medicine is presented in Section 7.7.2. 4048

9.2 Requirements on Radiological protection 4049

4050

(185) In its Publications 85 and 113, the Commission recommends a second level of 4051

RP training for interventional radiologists and cardiologists, in addition to the training 4052

recommended for other physicians who use X-rays (ICRP 85, 2000, ICRP 113, 2009). 4053

The Commission also recommends that nurses and other healthcare professionals who 4054

assist during fluoroscopic procedures should be familiar with radiation risks and 4055

precautions, in order to minimise their own exposure and that of others. 4056

(186) Training activities in RP should be followed by an evaluation of the knowledge 4057

acquired from the training programme. Education and training in RP should be 4058

complemented by formal examination systems to test competency before the person is 4059

awarded certification. If certification in RP is required for some medical specialties (e.g. 4060

interventional cardiology), certification should be obtained before the professional 4061

practices the specialty.. Training programmes should include both initial training for all 4062

incoming staff and regular updating and retraining. Scientific and professional societies 4063

should contribute to the development of the training syllabuses to ensure a consistent 4064

approach, and to promote and support the education and training. Scientific congresses 4065

should include refresher courses on RP, attendance at which could be a requirement for 4066

continuing professional development for professionals using ionising radiation. (ICRP 4067

113, 2009). 4068

(187) The International Basic Safety Standards for Protection against Ionising 4069

Radiation and for the Safety of Radiation Sources (BSS), published by the International 4070

Atomic Energy Agency (IAEA) and jointly sponsored by the Food and Agriculture 4071

Organization (FAO), the International Labour Organization (ILO), the Pan American 4072

Health Organization (PAHO) and the World Health Organization (WHO) (IAEA, 1996), 4073

require appropriate training that is sufficient to perform assigned tasks in the conduct of 4074

diagnostic or therapeutic procedures involving radiation. 4075

(188) The Medical Exposure Directive of EC 97/43/Euratom considers interventional 4076

radiology (Article 9) as a special practice involving high doses to patients (EU, 1997). 4077

According to Article 7, Member States shall ensure that the practitioner has adequate 4078

theoretical and practical training for the purpose of radiological practice as well as 4079

relevant competence in radiological protection. No special mention is made of 4080

interventional cardiology. 4081


109

4082

(189) Legislation in most countries requires that individuals who take responsibilities 4083

for medical exposure must be properly trained in RP. However, a training system and 4084

accreditation mechanism is still lacking in many countries. 4085

9.3 Training guidelines, curricula and materials 4086

4087

(190) The Commission, in Publication 85 (ICRP, 2000), states that interventional 4088

procedures are complex and demanding and that radiation dose tends to be operator 4089

dependent. It is particularly important that individuals performing these procedures are 4090

adequately trained both in clinical techniques and in radiological protection. It further 4091

states that special additional training should be planned when new x-ray systems or 4092

techniques are implemented in a centre. Basic and continuing training in radiological 4093

protection should be an integral part of this education. Training requirements are 4094

addressed in Publication 113 (ICRP 113, 2009). 4095

(191) In view of the number of radiation-induced injuries reported in recent years 4096

among patients undergoing interventional procedures (Rehani and Ortiz-Lopez, 2005, 4097

Vano and Gonzalez, 2005, ICRP, 2000, Koenig et al, 2001), a number of organizations 4098

have begun to provide recommendations for training requirements. Published guidelines 4099

were initially for interventional radiologists, but they are gradually becoming available 4100

from cardiology societies. 4101

4102

9.3.1 USA 4103

4104 (192) The Food and Drug Administration (FDA) advisory of 1994 (FDA, 1994) 4105

alerted facilities to ensure proper training. FDA‘s specific recommendations for facilities 4106

in which invasive procedures are performed included the following: 4107

4108

Assure appropriate credentials and training for physicians performing 4109

fluoroscopy. 4110

All operators of the system must be trained and understand the operation of the 4111

fluoroscopic system, including the implications for radiation exposure from each 4112

mode of operation. 4113

Facilities should ensure that physicians performing fluoroscopic procedures are 4114

educated so that they may, on a case-by-case basis, assess risks and benefits for 4115

individual patients, considering variables such as age, beam location and 4116

direction, tissues in the beam and previous fluoroscopic procedures or radiation 4117

therapy. 4118

4119

(193) In 1995, the American College of Cardiology Cardiac Catheterization 4120

Committee published a Position Statement indicating that appropriate training of staff is 4121

imperative, and that ‗‗Proper instruction in the principles of radiation physics and safety 4122

should be a part of every cardiologist‘s education‖ (Brinker et al., 1995). The American 4123


110

College of Cardiology Consensus Document further clearly delineated the need for a 4124

radiation safety knowledge base for cardiology staff (Limacher et al., 1998). 4125

(194) In 2004, an American College of Cardiology/American Heart Association/ 4126

American College of Physicians (ACC/AHA/ACP) Task Force published a further report 4127

on clinical competence and training as a companion to the ACC‘s 1998 report (Hirshfeld 4128

et al, 2004; Limacher et al, 1998). The proposed curriculum in the 2004 document 4129

specifies the knowledge that a qualified physician should possess in order to be 4130

credentialed to use x-ray fluoroscopic machines, but does not specify a minimum number 4131

of hours of training. Physicians who have completed training should be able to 4132

demonstrate that they possess the knowledge specified by the curriculum by passing an 4133

appropriate certifying examination. 4134

(195) The necessary knowledge depth varies, depending upon the types of 4135

fluoroscopically guided procedures a particular physician performs. The ACC/AHA/ACP 4136

document outlines two different curricula—basic and advanced. The basic curriculum is 4137

appropriate for physicians who perform simpler fluoroscopically guided critical-care unit 4138

procedures such as right heart catheterization, temporary pacemaker placement, and intra-4139

aortic balloon pump placement. The advanced curriculum is appropriate for physicians 4140

who perform angiographic, interventional, and electrophysiological procedures that 4141

employ greater amounts of radiation in more complex circumstances with different 4142

purposes and a greater attendant risk of patient and personnel injury. 4143

(196) The National Council on Radiation Protection and Measurements (NCRP) in 4144

the U.S. recently published a report on radiation dose management for fluoroscopically 4145

guided interventional medical procedures (NCRP, 2010). This report makes a number of 4146

specific recommendations, including: 4147

4148

Each individual present in a fluoroscopically guided interventional (FGI) 4149

procedure room shall have appropriate radiological protection training. 4150

Every person who operates or supervises the use of FGI equipment shall have 4151

current training in the safe use of that specific equipment. 4152

Interventionalists who perform FGI procedures or other procedures with the 4153

potential for high patient doses require additional knowledge and training beyond 4154

that necessary for interventionalists whose practice is limited to low-dose FGI 4155

procedures. 4156

Clinical training and experience is not an acceptable substitute for formal training 4157

in radiation management. 4158

9.3.2 European Commission 4159

(197) In compliance with European Commission requirements, an outline for specific 4160

training in radiological protection for interventional radiology has been developed (EC, 4161

2000; Vañó et al. 1997). Although there is no special mention of interventional 4162

cardiology in the group of professionals, the table giving suggested number of training 4163

hours has a column for interventional cardiology specialists; 20-30 hours of training are 4164

suggested. The initial Spanish experience, based on these guidelines, has been reported 4165

(Vañó, 2003). This included development of a training CD (MARTIR, 2002). 4166


111

9.3.3 International Atomic Energy Agency 4167

4168

(198) The International Atomic Energy Agency (IAEA) has developed a curriculum 4169

with educational objectives specifically for interventional cardiologists. It is directed 4170

primarily at developing countries where the cardiology professional societies are not yet 4171

sufficiently robust to develop their own separate modules for basic and advanced 4172

curricula in the field of radiological protection. For these countries a ―sandwich‖ module 4173

is ideal, particularly in view of the lack of individuals with sufficient expertise in 4174

radiological protection in diagnostic imaging to teach the subject. IAEA has also 4175

prepared educational material in the form of an electronic presentation on CD. This 4176

IAEA training material on Radiation Protection in Cardiology is available without cost 4177

and can be obtained by writing to [email protected] or downloaded from the 4178

website http://rpop.iaea.org. 4179

9.3.4 WHO 4180

4181

(199) The World Health Organization (WHO) has stated that specific training in 4182

interventional radiology is required in addition to basic training and has provided training 4183

requirements (WHO 2000). WHO further stated that the training process must be 4184

continued when new techniques are introduced, when new radiological systems are 4185

installed and when new staff are appointed. It also recommended continuous training and 4186

refresher courses at regular intervals. However, interventional cardiology was outside the 4187

scope of this document. 4188

9.4 Credentialing 4189

4190

(200) There is a distinction between the credentialing of a physician as technically 4191

competent to perform a procedure versus the credentialing of the same physician as 4192

competent to safely use a fluoroscope. Since the amount of radiation employed by the 4193

interventional cardiologist both per patient and annually is no less than that used by an 4194

interventional radiologist, the training standards of radiation physics and radiological 4195

protection in interventional cardiology should be the same as for other interventionalists 4196

(ICRP 113, 2009). 4197

9.5 References 4198

4199

Brinker, J.A. et al, 1995. Position paper of the American College of Cardiology Cardiac 4200

Catheterization Committee. JACC 26, 319-325. 4201

EU, 1997. Council Directive 97/43 Euratom, on health protection of individuals against the 4202

dangers ionizing radiation in relation to medical exposure, and repealing Directive 4203

84/466 Euratom. Official Journal of the European Communities No L 180, 9th July 4204

1997:22-7. 4205

http://europa.eu.int/comm/energy/nuclear/radioprotection/legislation_en.htm 4206

mailto:[email protected]

http://rpop.iaea.org/


112

EC, 2000. Guidelines on education and training in radiation protection for medical 4207

exposures. Radiation Protection 116, European Commission. Directorate General 4208

Environment, Nuclear Safety and Civil Protection. Luxembourg, 2000. Available at: 4209

http://ec.europa.eu/energy/nuclear/radiation_protection/doc/publication/116.pdf 4210


FDA, 1994. Avoidance of serious x-ray-induced skin injuries to patients during 4212

fluoroscopically-guided procedures. Statement 9 Sept. 1994, Food and Drug 4213

Administration, Rockville, MD, USA. 4214

Hirshfeld, J.W., Jr., Balter, S., Brinker, J.A., Kern, M.J., Klein, L.W., Lindsay, B.D., 4215

Tommaso, C.L., Tracy, C.M., Wagner, L.K., 2004. ACCF/AHA/HRS/SCAI clinical 4216

competence statement on physician knowledge to optimize patient safety and image 4217

quality in fluoroscopically guided invasive cardiovascular procedures: a report of the 4218

American College of Cardiology Foundation/American Heart Association/American 4219

College of Physicians Task Force on Clinical Competence and Training. J. Am. Coll. 4220

Cardiol. 44, 2259-2282. 4221

IAEA, 1996. International Basic Safety Standards against Ionizing Radiation and for the 4222

Safety of Radiation Sources, Safety Series No. 115, Vienna: IAEA. 4223

ICRP, 2000. Avoidance of radiation injuries from medical interventional procedures. ICRP 4224

Publication 85, Annals of the ICRP 30 (2). 4225



Ann ICRP 39 (5). 4228

Koenig TR, Wolff D, Mettler FA, Wagner LK. Skin injuries from fluoroscopically guided 4229

procedures: Part 1, Characteristics of radiation injury. AJR 2001; 177: 3-11 4230

Limacher, M.C. et al, 1998. Radiation safety in the practice of cardiology. JACC 31, 892-4231

913. 4232

MARTIR (Multimedia and Audiovisual Radiation Protection Training in Interventional 4233

Radiology), 2002. CD-ROM. Radiation Protection 119, European Commission. 4234

Directorate General Environment, Nuclear Safety and Civil Protection. Luxembourg 4235

(free availability at 4236

http://ec.europa.eu/energy/nuclear/radiation_protection/publications_en.htm; go to 4237

publication 119). 4238

NCRP, 2010. Radiation dose management for fluoroscopically guided medical procedures. 4239

Report No. 168. National Council on Radiation Protection and Measurements, 4240

Bethesda, MD. 4241

Rehani, M.M. and Ortiz-Lopez, P., 2006. Radiation effects in fluoroscopically guided 4242

cardiac interventions - keeping them under control. Int. J. Cardiol. 109(2), 147-151. 4243

Vano E, and Gonzalez L. 2005. Accreditation in radiation protection for cardiologists and 4244

interventionalists. Radiat Prot Dosimetry. 117(1-3):69-73. 4245

Vañó, E., Gonzalez, L., Faulkner, K. et al, 1997. Specific training objectives in radiation 4246

protection for medical staff in interventional radiology installations. Draft document. 4247

DIMOND European Concerted Action. 4248

Vañó, E., Gonzalez, L., Canis, M. et el., 2003. Training in radiological protection for 4249

interventionalists. Initial Spanish experience. BJR 76, 217-219. 4250

http://ec.europa.eu/energy/nuclear/radiation_protection/doc/publication/116.pdf

http://ec.europa.eu/energy/nuclear/radiation_protection/publications_en.htm


113

WHO, 2000. Efficacy and radiation safety in interventional radiology. World Health 4251

Organisation, Geneva. 4252

4253

4254

4255


114

10. QUALITY ASSURANCE PROGRAMMES 4256

4257

Main Points 4258

Two basic objectives of the radiological protection quality assurance 4259

programme (QAP) are to evaluate patient radiation dose on a periodic basis 4260

and to monitor occupational radiation dose for workers in cardiology facilities 4261

where radiation is used. 4262

Training in RP (both initial and retraining) should be included in the QAP for 4263

all staff involved in interventional cardiology procedures. 4264

A cardiologist should be in charge of the QAP aspects of RP for cardiology 4265

procedures, and should be assisted by a medical physicist. 4266

A senior interventionalist and a medical physicist should be included in the 4267

planning for a new interventional fluoroscopy laboratory, installation of a new 4268

x-ray or nuclear medicine system and the upgrade of existing equipment. 4269

Periodic evaluation of image quality and procedure protocols should be 4270

included in the QAP. 4271

The QAP should ensure the regular use of personal dosimeters and include a 4272

review of all abnormal dose values. 4273

The QAP should establish a trigger level for individual clinical follow-up when 4274

there is a risk of radiation-induced skin injuries. 4275

Patient dose reports should be produced at the end of procedures, archived 4276

and recorded in the patient’s medical record. If dose reports are not available, 4277

dose values should be recorded in the patient’s medical record together with 4278

procedure and patient identification. 4279

Patient dose audits (including comparison with DRLs) and reporting are 4280

important components of the QAP. 4281

4282

4283


(201) Quality assurance programs in cardiology should cover all of the planned and 4286

systematic actions necessary to provide confidence that optimum quality has been achieved 4287

in the entire diagnostic process, i.e. there is consistent production of adequate diagnostic 4288

information with the lowest acceptable exposure of patients and personnel (WHO 1982). 4289

(202) A quality assurance programme (QAP) for interventional cardiology includes all 4290

of the aspects of radiological protection (RP) of patients and staff in addition to the usual 4291

clinical aspects. Only the RP aspects are discussed here. Two basic objectives of the QAP 4292

are to evaluate patient radiation dose on a periodic basis and to monitor occupational 4293

radiation dose for workers in cardiology facilities where radiation is used. Table 10.1 4294

summarizes the 10 key points to be included in a RP QAP. The RP component of the QAP 4295

for interventional cardiology should be an independent portion of the general QAP for x-4296

ray installations in a particular health centre. 4297


115

(203) A cardiologist should be in charge of the QAP aspects of RP for cardiology, and 4298

should be assisted by a medical physicist. The RP QAP for cardiology should be reviewed 4299

at least annually, to allow the opportunity for updates and periodic follow up. Self-audit of 4300

the QAP is also advisable. Table 10.2 presents some questions to be answered as part of 4301

this internal audit of the QAP. 4302

4303

10.2 Facilities 4304 4305

(204) The design of a new interventional fluoroscopy laboratory, the selection and 4306

installation of a new x-ray or nuclear medicine system and the upgrade of existing 4307

equipment are all complex and expensive processes. Planning for these processes should 4308

include RP. Both a senior physician (interventionalist, nuclear medicine specialist or CT 4309

imaging specialist, as appropriate) and a medical physicist should be included in this 4310

planning. Physicians representing all of the medical specialties who will be using the new 4311

room should be involved in specifying the equipment for the room. Important aspects to 4312

consider are shown in Table 10.3. 4313

(205) Suggested architectural specifications for catheterization laboratories have been 4314

published by scientific societies (ACC/AHA 1991): adequate dimensions (50 m2), a 4315

sufficiently large control room with a wide leaded window, sufficient ceiling height (3 m, 4316

allowing for ceiling suspended support of the C-arm, monitors, etc.), appropriate radiation 4317

shielding (including window and doors), easy access for personnel and patients, etc. New x-4318

ray rooms should be of sufficient size to allow personnel to be positioned at a distance from 4319

the patient when inside the X ray room during the procedures. The installation should 4320

include a control room with a wide shielded glass window, so that other clinicians and other 4321

personnel can follow the procedures without radiation exposure. 4322

(206) Appropriate shielding, access to the x-ray room and RP tools (aprons, thyroid 4323

protectors, protective gloves and glasses, protective screens, ceiling-suspended and under-4324

table shields), should be part of the planning for catheterization laboratories. 4325

Dose reduction technology, including the capabilities to measure, record, and transfer 4326

patient dose data to the patient‘s medical record, should be considered an important factor 4327

in the selection of new fluoroscopy and CT equipment. Appropriate standards should be 4328

taken into account (IEC 2010). 4329

4330

10.3 Acceptance and constancy testing 4331 4332

(207) Acceptance tests shall be made by the company supplying the equipment in the 4333

presence of technical personnel from the centre buying the system, or by centre technical 4334

personnel. Commissioning of the new equipment before its clinical use should be the 4335

responsibility of the personnel of the centre. 4336

(208) Periodic quality controls (QC), including dosimeter calibration, should be 4337

planned taking into account international standards, local recommendations and the 4338

recommendations of the x-ray system manufacturer. These should also include practical 4339

results for the appropriate management of patient doses by the cardiologists (e.g. dose rate 4340


116

in the different fluoroscopy modes, dose per frame during cine acquisition, CT scan 4341

protocols). 4342

(209) Periodic evaluation of image quality and procedure protocols should also be 4343

included in the QAP. Image quality should be measured with test objects during the 4344

acceptance and constancy tests. With the new digital imaging detectors it is possible to 4345

select a wide range of dose values to obtain the required level of quality in the images. It is 4346

easy to specify excessive dose rates, as these do not impair image quality and are not easily 4347

detected from inspection of the image. Cardiologists, in cooperation with the medical 4348

physicist and the industry engineer should set the fluoroscopic or CT system doses to 4349

achieve the appropriate balance between image quality and dose. 4350

(210) It is possible to perform this periodic evaluation of image quality using clinical 4351

criteria. The European consortium DIMOND (DIMOND 2008) has proposed a set of 4352

criteria to evaluate fluoroscopic cardiac imaging (Bernardi 2001a and 2001b). 4353

(211) Cardiologists should learn the dose required to obtain a certain level of 4354

diagnostic information. For interventional fluoroscopy, this is related to fluoroscopy time, 4355

number of series, number of frames/series, fluoroscopy and cine modes and dose rates, 4356

etc.). It is also important to verify that wedge filters, collimation and C-arm angulations are 4357

used properly. CT scan protocols, modes, and technique factors, and their effect on patient 4358

dose, are discussed in Chapter 8. Concerns related to nuclear medicine doses are discussed 4359

in Chapter 7. 4360

4361

10.4 Staff 4362 4363

(212) An important aspect of the QAP is a description of the roles and responsibilities 4364

of personnel. There should be enough staff to avoid an excessive number of procedures per 4365

specialist, and sufficient nursing and technologist support. Support by network specialists 4366

(for new digital systems), maintenance and service personnel and medical physics 4367

specialists is advised. 4368

(213) Analysis of staff radiation dose should be included in the QAP. Calibrated 4369

dosimeters for staff must be available. In addition to the dosimeter in the x-ray system for 4370

the evaluation of patient dose, personnel working in the catheterization laboratories should 4371

wear appropriate dosimeters, and a strict policy for their use should be implemented. 4372

Additional electronic dosimeters may also be useful, especially for RP training of students 4373

and inexperienced personnel. The QAP should ensure the regular use of personal 4374

dosimeters and include a review of all abnormal dose values. 4375

4376

10.5 Training 4377 4378

(214) Training in RP is another important item to be included in the QAP. Initial 4379

accreditation in RP should follow local requirements. Special attention to training in RP 4380

should be given to fellows and residents. Seminars to analyse patient and staff dose results 4381

can be an excellent educational tool as well as a useful QA activity. Training is discussed in 4382

more detail in chapter 9 and in ICRP Publication 113 (ICRP, 2009). 4383

4384


117

10.6 Follow-up for possible radiation-induced skin injuries for interventional 4385

fluoroscopy procedures 4386 4387

(215) The QAP should establish a trigger level for individual clinical follow-up when 4388

there is a risk of radiation-induced skin injuries (ICRP 2000; WHO 2000; NCRP 168). The 4389

Substantial Radiation Dose Level (SRDL) is a threshold value that is used to trigger 4390

additional dose management actions, including patient follow-up (NCRP 2010). There is no 4391

implication that a radiation dose below the SRDL is completely safe or that a radiation dose 4392

above the SRDL will always cause an injury. Some suggested values are a skin dose of 3 4393

Gy, a KAP of 500 Gy·cm2, or an air kerma at the interventional reference point of 5 Gy 4394

(NCRP 168). For cardiology procedures, a KAP between 150 and 250 Gy·cm2 may be 4395

more appropriate, depending on the radiation field size and the specific protocols. These 4396

values could indicate peak skin doses greater than 2 Gy in a single procedure. These values 4397

are intended to trigger follow-up for a radiation dose that might produce a clinically 4398

relevant injury in an average patient. Lower values may be used at the discretion of the 4399

facility, especially when previously irradiated skin is involved (NCI 2005). 4400

(216) If the trigger level has been exceeded, the patient‘s personal physician should be 4401

informed about the patient‘s radiation dose and the possibility of ionising radiation effects. 4402

Appropriate clinical follow up should be arranged. If the dose estimate after the procedure 4403

is close to the threshold for deterministic effects then the patient should be informed of 4404

possible symptoms or observable skin effects by the interventionist or his/her staff. 4405

Information about what the patient should do in case these effects appear should be 4406

provided. 4407

4408

10.7 Dose audits 4409 4410

(217) Patient dose audits and reporting are important components of the QAP. Patient 4411

dose reports should be produced at the end of procedures, archived, and transferred to the 4412

patient‘s medical record. An example of a patient dose report is presented in chapter 5, Fig 4413

5.2. If such reports are not available, dose values should be recorded together with the 4414

procedure and patient identification (Miller et al, 2004). If the reports are available only in 4415

hard copy (printed), relevant data should be transferred to an electronic database for further 4416

analysis. If the reports are available in electronic format, the files should be archived 4417

together with the images. For interventional fluoroscopy, quantities to be measured and 4418

recorded periodically for a significant number of patients include: KAP, reference point air 4419

kerma (if available in the x-ray system), fluoroscopy time, number of series, and number of 4420

frames (NCRP, 2010). Reference point air kerma measurement capability has become 4421

widely available in fluoroscopic equipment manufactured after mid-2006. For CT 4422

examinations, the quantities are CTDIw, CTDIvol or DLP (section 8.3). For nuclear 4423

medicine studies, the quantity is administered activity. 4424

(218) Dose audits should include an evaluation of the centre‘s performance with 4425

respect to established reference levels (section 10.7.1). Dose audits for interventional 4426

cardiology procedures require additional analyses (sections 10.7.3, 10.7.4), because these 4427

procedures also present a risk of deterministic injury. 4428


118

4429

10.7.1 Diagnostic Reference Levels 4430 4431

(219) Dose guidelines were first introduced in the U.S and the U.K. in the late 1980s 4432

and early 1990s (Wall, 1998). They were introduced into ICRP recommendations as 4433

―investigation levels‖ in Publication 60 (ICRP, 1990) and as ―diagnostic reference levels‖ 4434

(DRLs) in Publication 73 (ICRP, 1996). DRLs are now an established method of defining 4435

feedback levels for high volume examinations such as chest radiographs or mammograms. 4436

The Commission continues to recommend their use (ICRP 85, ICRP 103, ICRP 105). 4437

4438

(220) DRLs are used to help avoid radiation dose to the patient that does not contribute 4439

to the medical imaging task. They provide practitioners with a straightforward tool for 4440

comparing the radiation doses that they deliver to their patients with the radiation doses 4441

delivered by their colleagues. They are a guide to good practice, but are neither dose limits 4442

nor thresholds that define competent performance of the operator or the equipment. They 4443

are intended to provide guidance on what is achievable with current good practice rather 4444

than optimum performance, and help identify unusually high radiation doses or exposure 4445

levels. A mean dose for a procedure that is less than the reference level does not guarantee 4446

that the procedure is being performed optimally. 4447

4448

(221) To use DRLs as a quality improvement tool, an institution or individual 4449

practitioner collects radiation dose data for cases of a procedure performed in their own 4450

practice. The recommended number of cases varies from 10 to >50, with the latter number 4451

suggested for interventional fluoroscopy procedures because of the high individual 4452

variability in patient dose of cases of image-guided interventional procedures (Wall, 1998, 4453

Vano 2008). The mean radiation dose for the procedure is then compared to the DRL. If 4454

local practice results in a mean radiation dose that is greater than the DRL, the fluoroscopic 4455

equipment should be investigated. If the fluoroscopic equipment is functioning properly 4456

and within specification, operator technique and procedure protocols should be examined 4457

(Vano, 2001). Investigations are also appropriate where local values are substantially below 4458

the DRL, as excessively low doses may be associated with poor image quality. 4459

4460

10.7.2 Application of Diagnostic Reference Levels in interventional fluoroscopy 4461

procedures 4462 4463

(222) At present, there is little evidence to indicate that dose levels are decreasing in 4464

interventional cardiology. If anything, dose levels are increasing due to the increased 4465

complexity of fluoroscopically guided procedures. As the Commission has noted, 4466

reference levels, in principle, could be useful for dose optimization in interventional 4467

fluoroscopy procedures (ICRP 105). However, patient dose distributions for interventional 4468

fluoroscopy procedures extend over a wide range and are very variable due to the differing 4469

complexity of the procedures, different patient sizes and different operational modes. The 4470

Commission has suggested that a potential approach to this problem is to take into account 4471


119

the relative ―complexity‖ of the procedure (ICRP 105). Other methods have also been 4472

proposed (NCRP 2010). 4473

(223) Recent studies have provided DRLs for cardiovascular procedures (Peterzol et al 4474

2005, Neofotistou et al 2003, Balter et al 2008, D'Helft et al 2009). Some diagnostic 4475

invasive procedures (e.g., routine coronary angiography) are done in a relatively 4476

standardized way and in sufficient volumes that a valid DRL might be constructed. 4477

(224) The European DIMOND consortium proposed provisional RLs for radiation 4478

doses delivered to patients during two types of invasive cardiology procedures, coronary 4479

angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA). The 4480

proposed DRLs for CA and PTCA were KAP values of 45 Gy·cm2 and 75 Gy·cm

2, 4481

fluoroscopy times of 7.5 min and 17 min and 1250 and 1300 frames, respectively. The 4482

consortium concluded that more studies were required to establish "tolerances" from the 4483

proposed levels, taking into account the complexity of the procedure and the patient's size. 4484

(225) Bernardi and co-workers performed studies in Udine, Italy (Bernardi, 2000) and 4485

later in several European hospitals (Neofotistou, 2003), with quantitative assessments of 4486

complexity in relation to a patient's exposure to radiation. The relationships between 4487

several clinical factors, anatomic factors and technical factors versus fluoroscopy time were 4488

evaluated for PTCA. A scoring system was developed, and two complexity indexes were 4489

conceived, based on which the procedures were divided into three groups: simple, medium, 4490

and complex. The relative complexity of procedures carried out in different centres should 4491

be taken into account when comparing typical patient doses with reference levels. 4492

(226) The IAEA carried out an international project to determine the feasibility of 4493

establishing guidance levels for cardiac catheterization and percutaneous coronary 4494

interventions (IAEA, 2009). The IAEA report has been summarized in a separate 4495

publication (Balter et al, 2008). For PTCA procedures, the report recommended the use of a 4496

reference level, using KAP, of 100 Gy·cm2 for simple procedures, 125 Gy·cm

2 for 4497

moderate complexity procedures and 200 Gy·cm2 for complex procedures. Unfortunately, 4498

methods for quantifying complexity have not yet been developed for other interventional 4499

cardiology procedures, such as electrophysiology ablation or pacemaker insertion. 4500

4501

10.7.3 Evaluation of high dose interventional fluoroscopy procedures 4502

4503 (227) Reference levels are used to evaluate the average dose per procedure. Because of 4504

the lognormal dose distribution that is characteristic of fluoroscopically guided 4505

interventions, an additional process is needed to evaluate the high dose ―tail‖. The high 4506

dose tail is of particular interest, because this tail represents the cases where patient doses 4507

may be high enough to cause deterministic effects. 4508

(228) Cases that required a radiation dose greater than the SRDL (section 10.6) should 4509

be identified and reported to the laboratory director and laboratory quality manager on a 4510

periodic basis. A monthly report is helpful, to ensure that patients with high radiation doses 4511

receive appropriate education and follow-up. 4512

(229) For each such procedure, the report should include patient identifier(s), the dose 4513

delivered during the procedure, the type of procedure, the room in which the procedure was 4514

performed, the operator‘s name, a count of the patient‘s previous invasive procedures 4515


120

(essential for estimating total skin dose), and any special notes. The goal of this report is to 4516

help assure that all patients who received a high radiation dose have been appropriately 4517

educated, and that appropriate follow-up is scheduled and performed (Miller et al, 2010). 4518

(230) Cases resulting in possible radiation injuries should be discussed at the next 4519

laboratory QA meeting. This discussion should include any available diagnoses, planned 4520

patient follow-up, and outcomes. Unless it is clear that the injury was not radiation-4521

induced, the procedure should be reviewed for the appropriate use of radiation in the 4522

clinical context (Miller et al, 2010). 4523

4524

10.7.4 Evaluation of skin dose for interventional fluoroscopy procedures 4525 4526

(231) It is advisable to measure the skin dose distribution in a sample of patients, to 4527

verify that basic aspects of patient protection are being followed (e.g. appropriate 4528

collimation, use of wedge filter, avoidance of a high concentration of radiation fields in the 4529

same skin area). (Vano 1997; Guibelalde 2003). Skin dose may be measured with special 4530

film, with dosimeters placed directly on the patient‘s skin, and by other means (Miller et al, 4531

2004). A qualified physicist should be consulted for these measurements. 4532

4533 4534

4535

4536


121

4537

Table 10.1. Some key aspects to be included in the section of radiological protection of 4538

the quality assurance programme for cardiac facilities using ionising radiation. 4539 4540

4541

1. Facility design. 4542

2. X ray equipment (selection criteria). 4543

3. Radiological protection tools. 4544

4. Availability of dosimeters. 4545

5. Availability of personnel and their responsibilities. 4546

6. Training in radiological protection (initial and continuing). 4547

7. Patient dose audit and reporting. 4548

8. Clinical follow up for high patient doses 4549

9. Image quality and procedure evaluation. 4550

10. Staff doses. 4551

4552

4553

4554

4555

4556

4557

Table 10.2. Examples of quality indicators 4558 4559

Can your centre report patient dose values from the last year? 4560

Do you have a procedure for the clinical follow-up of high doses to patients? 4561

Do you know the results of your x-ray system QCs? 4562

Are you following your staff dose values? 4563

Do you have a continuous training programme in RP? 4564

4565


122

Table 10.3 Facility procurement considerations (ICRP, 2000) 4566 4567

Analysis of clinical need Workload 4568

4569

Equipment specification General requirements 4570

Major equipment components 4571

Functional requirements 4572

Specific equipment requirements 4573

4574

Computer capabilities Image display matrix 4575

Processing times 4576

Memory/image storage 4577

PACS linkages* 4578

HIS linkages† 4579

4580

Systems performance Image quality 4581

Patient dose 4582

Dose control measures 4583

4584

User manuals Technical training 4585

Operational training 4586

4587

Compliance with national Electrical safety 4588

and international standards Mechanical safety 4589

Radiation safety 4590

Room design/shielding 4591

4592

Service and warranty Maintenance programme 4593

Quality control programmes 4594

Access to service software protocols/ 4595

rationale for service schedules 4596

4597

Operation costs Cost of consumables - projected over 5 years 4598

4599

*PACS=picture archiving and communication system 4600

†HIS=hospital information system 4601

4602


123

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