angiography equipment

International Atomic Energy Agency

Angiography EquipmentAngiography Equipment

L 4

Lecture 4: Angiography equipment 2Radiation Protection in Cardiology

Educational objectivesEducational objectives

• What are equipment standards for cath equipment (FDA, IEC), particular needs for pediatric patients.

• What to look for while establishing a cath lab.

• Importance of testing equipment performance.


Equipment standardsfor Cath Lab


X-Ray Equipment Standards X-Ray Equipment Standards And RegulationsAnd Regulations

• Standards are consensus guides from the manufacturing community, not regulatory

• Several groups set standards regarding equipment, e.g., International Electrotechnical Equipment (IEC)

• Apply to electrical, mechanical, and radiation safety

• Apply to equipment at time of manufacture and installation


What to look for while establishing a What to look for while establishing a cath. lab.cath. lab.

• If the relevant Standards are fulfilled.

• If a medical physicist is available.

• If radiation protection tools are available.

• If patient dose measuring and recording system is available.

• If acceptance tests, commissioning and quality assurance programme have been foreseen.


What to look for while establishing a What to look for while establishing a cath. lab.cath. lab.

• If the X rays system selected is appropriate for the procedures to be carried out in the catheterization laboratory.

• If some other relevant information described in ACC/AHA Guidelines and AAPM-70 (described in this lecture) have been taken into account.


OutlineOutline

• FDA, IEC and ACR recommendations concerning X-ray equipment for cardiology.

• AAPM report and specific pediatric equipment recommendations.

• Key topics for cardiac X-ray equipment.

• IAEA survey and importance of testing equipment.

• Patient dose reports and DICOM header information.


Limitation in entrance exposure rateLimitation in entrance exposure rate

Federal Register: May 19, 1994. 21 CFR Part 1020.Federal Performance Standard for Diagnostic X-Ray Systems and Their Major Components; Final Rule.DEPARTMENT OF HEALTH AND HUMAN SERVICESFood and Drug Administration


Limitation in entrance exposure rateLimitation in entrance exposure rate

• The Standard for Diagnostic X Ray Systems (May 19, 1994), limits the entrance exposure rate of fluoroscopic x ray systems during normal fluoroscopy to 10 R/min unless an optional high-level control (HLC) is activated.

• If HLC is activated, the entrance exposure rate must be limited to 20 R/min.

• The entrance exposure rate limits do not apply during the recording of images.


Measuring entrance dose and

image quality

Test object to measure image quality, at the

isocenter

Flat ionisation chamber to

measure phantom entrance dose


Typically we can find the following fluoroscopy setting:

Entrance dose PMMA with BS (II 23 cm) R2_08/03

0.020.040.060.080.0

100.0120.0140.0

16 20 24 28

cm PMMA

mG

y/m

in low

med

high


Entrance dose PMMA (with BS) R2_08/03

0

200

400

600

800

16 20 24 28

cm PMMA

mic

roG

y/fr

ame

cine 23 cm

cine 17 cm

Typically we can find the following cine setting


Proposed RuleDecember 10, 2002


mGy (total)mGy/min

(at 15 cm from the isocenter towards the x-ray source)

Fluoroscopy time


Fluoroscopic equipment manufactured on or after May 19, 1995:

Shall not be operable if AKR is higher than 88 mGy/min (10 R/min).

Exceptions: •When a mode a high-level control is activated: 180 mGy/min (20 R/min). A continuous signal audible to the fluoroscopist shall indicate that the high-level control is being employed.• During the recording of images (archiving of fluoroscopic or radiographic images in analog format with a video-tape or video-disc recorder does not qualify as an exception).

Limits:88 mGy/min

180 mGy/min


IEC Standard 2000


IEC standard on Interventional IEC standard on Interventional RadiologyRadiology

• Radioscopically guided invasive (and interventional) procedures.

• Interventional reference point.

• Isokerma maps shall be provided.

• The anti-scatter grid should be removable without the use of tools.

• Dosimetric indications: reference air kerma rate, cumulative reference air kerma. cumulative area kerma product, (shall be accurate to within 50 %).

• Supplementary indications: cumulative time of radioscopy, cumulative number of radiographic irradiations, integrated reference air kerma.

Lecture 4: Angiography equipment 19Radiation Protection in CardiologyTransmission chamber and collimators (Siemens system)


• Collimation: Dual-shape collimators incorporating both circular and elliptical shutters may be used to modify the field for cardiac contour collimation. Partially absorbent contoured filters are also available to control the bright spots produced by the lung tissue bordering the heart.


Philips systems


Example of the influence of wedge filter in the skin dose (Vano)


• Image intensifiers. Because of the necessity of imaging large fields (e.g., for ventriculography, aortography) as well as small fields (coronary arteries), multimode (double or triple) cesium iodide image intensifiers are recommended. Formats available vary with the manufacturer but are typically 9 in/ 6 in/4.5 in (9/6/4.5), 9/6, 10/4, and 9/5.


• Patient and Equipment Support: The ability to obtain very steep sagittal plane angulation (in excess of 45 ) is desirable.

• An image intensifier with a diameter of more than 9 in is not recommended for cardiac catheterization laboratories because its size interferes with the ability to obtain steep sagittal angulation.


• The operator should be made aware of the cumulative amount of exposure time during the procedure.

• In training programs there should be a limit to the amount of fluoroscopic time granted to a trainee to complete a specific task, based on a number of considerations such as the progress being made and the complexity of the procedure.


• A freely movable lead glass or acrylic shield suspended from the ceiling should be used. Its sterility may be maintained by using disposable plastic covers.

• Each procedure room should have a detailed determination of exposure levels performed by a qualified radiation physicist.

• There is a tendency in the busy laboratory to assign a low priority to preventive maintenance and quality assurance inspections.


AAPM-70 (2001)AAPM-70 (2001)

• The generator should be capable of generating 80 to 100 kilowatts (kW) of power.

• The generator design should result in “square wave” kVp pulses to achieve optimum patient dose savings.


AAPM-70 (2001)AAPM-70 (2001)

• Several manufacturers are using relatively thick copper filtration and reduced kVp during fluoroscopy to generate an energy spectrum better matched to the K-edge of iodine contrast media.

• This technique requires high fluoroscopic tube currents with the benefit of reducing patient exposure to radiation while improving image contrast.


AAPM-70 (2001)AAPM-70 (2001)

• For adult studies, a 9 to 11 inch (23 to 27 cm) size is used.

• Pediatric cardiac studies use smaller FoVs due to the small size of the pediatric heart.

• The 4.5 inch (11 cm) FoV would be commonly employed for most pediatric imaging studies.


AAPM-70 (2001). Pediatrics.AAPM-70 (2001). Pediatrics.

• If the cath lab will serve the pediatric population, the generator design should allow high quality imaging on patients which range in size from 3 to 140 kilograms (kg).

• This wide range of patient size places additional demands on the design of the generator.



• The generator design should allow the mAs loading of the tube per cine pulse to be varied from as little as 0.1 mAs (100 mA and 1 msec) up to 6 mAs (e.g., 800 mA and 7 msec) as a function of patient size in order to maintain a kVp operating range of 65 to 75 kVp.



• Cine frame rate capability should extend up to at least 60 fps for small children.

• The generator should support an x-ray tube with a minimum of three focal spots. Patients up to 3 to 4 years old can be imaged with an 0.3 mm focal spot size, and patients up to

• 8 to 9 years old can be imaged with cine using an 0.6 mm focal spot.



• The 0.3 mm focal spot can also be used on small children by removing the anti-scatter grid and employing a geometric magnification factor up to 2.

• The geometrical magnification method for small children can also reduce patient dose because the electronic magnification modes of the image intensifier are avoided and the Bucky factor due to the grid is eliminated.


Cardiology equipmentCardiology equipmentkey topicskey topics


Key topicsKey topics• Spatial beam modulation: collimation (and

virtual collimation), wedge filters, etc.

• Temporal beam modulation: pulsed fluoroscopy (grid controlled, temporal integration, etc).

• Beam quality modulation: extra filtering (Cu, Ta, etc).

• Last image hold.

• Patient dose measurement, display and archive.

• New detectors (dynamic flat panel), connectivity and DICOM compliance.

Lecture 4: Angiography equipment 37Radiation Protection in CardiologyControl panel indications (Siemens system)

Lecture 4: Angiography equipment 38Radiation Protection in CardiologyX-ray room indications (Siemens system)


Key topicsKey topics

• Ergonomy in the room and system geometry.

• Accidental stop of the system.

• Dosimetric indications in the system and inside the cath lab.

• Protective tools in the system.

• Operational modes and how they are settled.

• DICOM header information.

• On line audit possibilities.


High filtration High filtration

• The introduction of additional filtration in the X ray beam (commonly copper filters) reduce the number of low energy photons and as consequence, saves skin dose for the patients.


• Additional Cu filters can reduce the skin dose by more than 70%.

• Some systems affer variable extra filtration (0.2 mm - 0.9 mm) that is automatically set according to patient weight and angulation of the C-arm.

• Automatic filter insertion try to keep the dose as low as possible without degrading image quality.

Reduction of Radiation Exposure with Reduction of Radiation Exposure with extra filtrationextra filtration


Pulsed fluoroscopyPulsed fluoroscopy

• Pulsed fluoroscopy can be used as a method of reducing radiation dose, particularly when the pulse rate is reduced.

• But … pulsed fluoroscopy does not mean that dose rate is lower in comparison with continuous fluoroscopy!!.

• Dose rate depends of the dose per pulse and the number of pulses per second.


Reduction of Radiation Exposure with Reduction of Radiation Exposure with virtual collimationvirtual collimation

• Radiation-free Collimation.

• Manipulation of diaphragms in Last Image Hold.

• No fluoroscopy required.


Example of X-ray system Example of X-ray system settingsetting


APR Philips Integris H5000 Room 3, December 2001

Fluo low Fluo med Fluo high


IAEA survey 2001-2003IAEA survey 2001-2003

X-ray systems evaluated:

9-15 from 5 countries


95

45

125

118

102

171

39

17

46

0

20

40

60

80

100

120

140

160

180m

icro

Gy

/fra

me

Integris BH3000 Uru

Picker CV-PRO Uru

Integris 5000 R3 Sp

Integris 5000 R4 Sp

Integris 3000 R2 Sp

GE Advantx LCV Sp

Siemens II yell Lu

Siemens flat yell Lu

GE Advantx CFM Chile

Cine mode 16 cm PMMA

Very different dose/frame values have been found


6.6

6.0

5.0 5.

4

4.3

9.8

16.4

12.7

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0fa

cto

r fo

r d

os

e in

cre

as

e

Integris BH3000 Uru

Picker CV-PRO Uru

Integris 5000 R3 Sp

Integris 5000 R4 Sp

Integris 3000 R2 Sp

GE Advantx LCV Sp

Siemens II yell Lu



Dose increase for cine from 16 to 28 cm PMMA

Also different dose increase with patient thickness


4.1

1.0

6.9

3.0

1.1

1.1 1.

21.

1

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

fac

tor

for

do

se

inc

rea

se

Integris BH3000 Uru

Picker CV-PRO Uru

Integris 5000 R3 Sp

Integris 5000 R4 Sp

Integris 3000 R2 Sp

GE Advantx LCV Sp

Siemens II yell Lu



Dose increase from fluoro medium to fluoro high (24 cm PMMA)

Also different dose increase with fluoroscopy modes


Conclusions from the IAEA surveyConclusions from the IAEA survey

• Patient dose and image quality depend largely on the settings made at the commissioning of the radiological equipment.

• For different systems and different operation modes, entrance air kerma can increase by a factor of 20 (including electronic magnification) for the same patient thickness.


• Increasing phantom thickness increases dose by an additional factor of up to 12.

• Differences in radiation doses from the evaluated systems show a potential for dose reduction whilst maintaining image quality.

Conclusions from the IAEA surveyConclusions from the IAEA survey


Importance of testing X ray equipmentImportance of testing X ray equipment

• Characterization of the X- ray system, that should be part of the acceptance and status tests, should inform cardiologists about the dose rates and dose/frame for the different operation modes and for the different patient thicknesses. Image quality shall also be evaluated.

• Regular constancy checks should verify if important changes could been occurred.


Examples of patient dose Examples of patient dose reportsreports


1 CARD FIXED Coro ND 1k 7s 15F/s 15-Jan-03 09:16:21A 81kV 744mA 6.0ms 200CL small 0.3Cu 17cm 211.4µGym² 36.2mGy 0LAO 0CRA 105F

2 CARD FIXED Coro ND 1k 6s 15F/s 15-Jan-03 09:17:01A 86kV 734mA 6.0ms 600CL small 0.2Cu 17cm 376.9µGym² 63.8mGy 29RAO 0CRA 94F

3 CARD FIXED Coro ND 1k 5s 15F/s 15-Jan-03 09:17:43A 124kV 553mA 8.0ms ****** small 0.2Cu 17cm 490.3µGym² 94.1mGy 48RAO 22CRA 75F

4 CARD FIXED Coro ND 1k 6s 15F/s 15-Jan-03 09:18:16A 115kV 591mA 8.0ms ****** small 0.2Cu 17cm 460.4µGym² 97.8mGy 48RAO 22CRA 84F

5 CARD FIXED Coro ND 1k ***** 15F/s 15-Jan-03 09:19:05A 96kV 714mA 8.0ms ****** small 0.2Cu 17cm 9.3µGym² 1.9mGy 15RAO 30CRA 2F

6 CARD FIXED Coro ND 1k ***** 15F/s 15-Jan-03 09:19:07A 102kV 666mA 8.0ms ****** small 0.2Cu 17cm 17.2µGym² 3.5mGy 15RAO 30CRA 3F

Example of the data included in the study report (Siemens)


Example of the data included in the dosimetric report (Philips):

Philips Integris 5000:

Coronary angiography

65% cine; 35% fluoroscopy

13 series, 728 frames

1,54 Gy.cm2/min

0,368 Gy.cm2/10 fr

1 min fluoroscopy =

39 fr = 3 s cine


Examples of information Examples of information contained at the DICOM contained at the DICOM

headerheader


GE ADVANTX LCV-DLX (Cardio mode)(0008,0032) : Acquisition Time : 19:24:33(0008,103E) : Series Description : CORONARIO(0018,0060) : KVP : 75(0018,1110) : Distance Source to Detector : 1060.000(0018,1111) : Distance Source to Patient : 705(0018,1149) : Field of View Dimension(s) 152(0018,1150) : Exposure Time : 328 (number fr x ms per fr)(0018,1151) : X-ray Tube Current : 81(0018,1510) : Positioner Primary Angle : -30 (left is +)(0018,1511) : Positioner Secondary Angle : 0 (cra is +)(0019,101B) : 1.2 (this is the focus size)(0019,101C) : 1 (Dose mode: 0,1, 2 and 3 for A,B,C and D)(0019,101F) : 4 (This is the real pulse time in ms)(0020,0013) : Image Number : 2 (this is the series number)(0028,0008) : Number of Frames : 82


Philips Integris 5000 cardio(0008,0032) : Acquisition Time : 12:36:27(0018,0060) : KVP : 83(0018,1030) : Protocol Name : 12.5 IPS Coronaria(0018,1110) : Distance Source to Detector : 940(0018,1150) : Exposure Time : 8(0018,1151) : X-ray Tube Current : 873(0018,1162) : Intensifier Size : 169.99998(0018,1510) : Positioner Primary Angle : -32.099998(0018,1511) : Positioner Secondary Angle : 0.69999999(0020,0013) : Image Number : 8(0028,0008) : Number of Frames : 73


Siemens Axiom Artis cardio (0008,0033) : Image Time : 15:38:32(0008,103E) : Series Description : Coro LD 1k T(0018,0060) : KVP : 68(0018,1110) : Distance Source to Detector : 920(0018,1111) : Distance Source to Patient : 759.99998(0018,1151) : X-ray Tube Current : 737(0018,1154) : Average Pulse Width : 6(0018,115E) : Image Area Dose Product : 1577(0018,1162) : Intensifier Size : 230(0018,1510) : Positioner Primary Angle : -0.2(0018,1511) : Positioner Secondary Angle : -0.3(0018,1702) : Collimator Left Vertical Edge : 0(0018,1704) : Collimator Right Vertical Edge: 1023(0018,1706) : Collimator Upper Horizontal Ed: 0(0018,1708) : Collimator Lower Horizontal Ed: 1023(0020,0012) : Acquisition Number : 13(0028,0008) : Number of Frames : 69


SummarySummary

• What to look for while establishing a cath lab

• FDA, IEC, ACR recommendations

• Specific aspects in paediatrics• Examples of patient dose

reports• Dose variation in cine & fluoro-

IAEA survey• DICOM header information

angiography equipment

Documents