ONLINE SELF-STUDYRadiation Safety for X-Ray Equipment Operators

Getting Going

The intent of this training module is to provide radiation safety training to employees and students of The University of North Carolina at Chapel Hill who operate diagnostic x-ray equipment in clinical and/or research settings.

To document your participation in this self-study, we have provided a short multiple choice test. A score of 80% or better must be achieved to receive credit for this safety training.

Click on the forward button at the end of the module to take the test.

Use the buttons below to navigate through the tutorial or click on the hyper-link on the index page to advance to topic of interest.

What is Radiation?

Radiation, simply put, is energy, and comes in many different forms. It can come from unstable atoms, or can be electrically (machine) produced.

Radiation is useful in medicine because it allows for the imaging and non-surgical treatment of internal structures and diseases.

UNC uses many forms of radiation for diagnosis, treatment, and research, including:

X-Ray Machines from Radiology Radiopharmaceuticals in Nuclear Medicine/PET Linear Accelerators and Sealed Radiation Sources in

Radiation Oncology Certain Hospital Labs

Radiation Units and TermsTerms used to describe radiation and radioactive materials

include: Exposure (R – Roentgen)

Electrical charge per unit mass of air produced by x or gamma rays.

Absorbed Dose (RAD – Radiation Absorbed Dose / Gray (Gy)) The amount of energy per unit mass absorbed by an irradiated

object. Note: 1 rad = 0.01 Gy.

Radiation Units and TermsTerms used to describe radiation and radioactive materials

include: Dose Equivalent (REM – Roentgen Equivalent Man /

Sievert (Sv)) Regulatory dose reporting unit Modified absorbed dose taking into account the biological

impact of the different types of radiation (i.e. beta particle, x-ray, neutron).

Note: 1,000 millirem (mrem) = 1 rem = 0.01 Sv.

Activity (Curie – Ci / Becquerel - Bq) The number of nuclear transformations occurring per unit of

time for a radioactive nuclide – describes the amount of radioactivity of a nuclide.

Note: 1 mCi = 37 mBq.

Background Radiation

We are all exposed to radiation everyday.The average US Citizen receives about 600

mrem per year from naturally-occurring and man-made sources of radiation.

That's the equivalent of approximately 20 two-view chest x-rays procedures at UNC.

This is mostly from natural sources of radiation, such as radon, cosmic radiation, and natural deposits in the earth.

Even our bodies contain natural radioactivity!

Radioactive Materials

Diagnostic Radiopharmaceuticals (such as Tc-99m, F-18, Tl-201, I-131, and I-125) are used in Nuclear Medicine for diagnostic procedures and emit gamma rays, which are a penetrating radiation, like x-rays.

These radionuclides remain in the patient after the study is over, but have short half-lives, so the patient and the people around him or her are not exposed for a long period of time.

Although radiation exposures may arise from the radiation emitted by radionuclides in patients, by accidental contamination of skin with radioactive materials, or by accidental ingestion of these materials (possibly through smoking or eating when hands are contaminated), there is, in general, no radiation hazard from these patients who have received diagnostic doses of radioactive materials.

No special precautions are needed in caring for them, and there are no restrictions on patient activities or contacts with other people.

Radioactive Materials, con’t. When Therapeutic

Radiopharmaceuticals or Sealed Sources are used, relatively large doses are involved, the patient can be a significant source of radiation exposure to staff, family and visitors.

When such procedures require that radiation precautions be put into effect, a radiation sign and a precaution sheet (like this one) will be posted on the door to the patient's room.

Radioactive Materials, con’t.Research and medical laboratories use

radionuclides that may emit beta particles and low-energy gamma rays.

Beta particles are not nearly as penetrating as gamma rays or x-rays. Weak and moderate energy betas will not even penetrate the skin.

The most important safety precaution for most of these radionuclides is to keep the material from contaminating the skin thereby avoiding the possibility of ingestion or absorption.

Signs and Labels

Containers of radioactive material and rooms where radioactive materials are stored or used, are posted with the following label.

Rooms or areas where radiation-producing equipment is used are posted with the following sign.

Radiation Risk AssessmentEffects of large doses of radiation are well-documented and understood.

The effects of the very low doses of radiation (like those encountered in the hospital setting) are not, however, so well understood.

When a large dose of radiation is increased to an even larger dose, the adverse effects become greater or more prevalent.

This dose vs. effect relationship can be thought of as linear, with confirmed and documented effects beginning at a certain "threshold" level of radiation dose.

But since this "threshold" level is far greater than any allowable occupational dose, health physicists "extend" what is known about higher doses of radiation down to "zero" dose.

In other words, any radiation dose is assumed to have some effect. This is a conservative model of the risk.

Consider that for very low doses of radiation the effect of most concern is cancer.

Radiation Risk Assessment, con’t.It is estimated that approximately 20% (1 in 5) of all deaths in the

United states are due to some type of cancer.

If every member of a population of 1 million were to receive 10 mrem of radiation, it is possible that 5 additional deaths would be observed. Remember that out of this population of 1 million, about 200,000 will die of cancer, making these few additional deaths statistically impossible to detect.

Additionally, the risk of cancer death is 0.08% per rem for doses received rapidly (acute) and might be 2 times (0.04%, or 4 in 10,000) less that that for doses received over a long period of time (chronic).

All activities carry some element of risk. Flying in an airplane, driving a car, smoking cigarettes, eating certain foods, and drinking alcoholic beverages are everyday activities that carry some risk. Many of us are willing to accept the risk from these activities. The risk is very small for the amounts of radiation encountered by employees at UNC Health Care System.

Radiation Protection at UNC Health Care SystemThe Radiation Safety section of the UNC-Chapel Hill

Department of Environment, Health & Safety (EHS) acts as an "agent" for the Radiation Safety Subcommittee, and manages the Health Care System’s radiation protection program.

Information on radiation safety may be obtained from the Radiation Safety Officer (RSO) at 919-962-5507.

A link to Radiation Safety's website is provided here: UNC Radiation Safety

For more information about radiation, click here: What You Need to Know About Radiation

Radiation Protection at UNC Health Care System, con’t.Radioactive materials are used by the UNC Health Care System

under a "broad medical license" issued by the state radiation protection regulatory agency -the North Carolina Radiation Protection Section (visit their website at: NC Radiation Protection)

UNC Health Care has been issued a "license" by the NCRPS to possess and operate linear accelerators in Radiation Oncology.

Additionally, all x-ray machines are "registered" with the NCRPS.

The UNC Health Care Radiation Safety Subcommittee oversees and approves all use of radioactive materials at this institution.

Refer to the "Notice to Employees" form issued by the NCRPS for important information (posted where radiation sources are used): Notice to Employees

Basic Radiation Safety PracticesNorth Carolina State regulations require that UNC

Health Care System have an ALARA program.

The main purpose of this program is to ensure that radiation exposures are maintained:

As Low As Reasonably Achievable.

The ALARA concept is based on the assumption that any radiation dose, no matter how small, can have some adverse effect.

Under the ALARA program, every reasonable means of lowering exposure is used.

Radiation exposure can be minimized (ALARA) by utilizing three basic principles:

Basic Radiation Safety PracticesTime: Time is used in radiation protection to limit the time spent

near a radiation source. Reducing the time decreases the radiation dose received.

Distance: Distance plays an important role in radiation protection. Increasing the distance from a source of radiation significantly reduces the radiation dose.

Doubling the distance from a radiation source means one-fourth the dose rate.

Tripling the distance gives one-ninth the rate.

Shielding: The use of appropriate shielding greatly reduces dose. The material used and thickness of the shield depends on the

source of the radiation. Lead is a common material used to shield radiation.

Basic Radiation Safety Practices, con’t.Radioactive Spills: When a spill of radioactive

material is encountered, do not clean it up.Remember that small droplets may have

splashed away from the spill.If liquid is running, try to contain it with a paper

towel or other absorbent material.Isolate the area and notify the Radiation

Safety Officer.All persons involved in a spill should be

monitored for contamination.

Dose Limits and Monitoring RequirementsThe amount of radiation received by persons exposed

occupationally should not exceed the dosages specified in the North Carolina Regulations For Protection Against Radiation:

15A NCAC 11 Annual Dose Limits: Whole Body: 5,000 mrem Skin/Extremities: 50,000 mrem Lens of Eye: 15,000 mrem

A member of the general public is allowed only 100 millirem per year from all licensed and registered radiation activities at UNC.

The average annual dose of a radiation worker at UNC is about 100 millirem.

A radiation worker is required to be monitored if he/she is likely to receive in excess of 10% of the dose limits.

Dose Limits and Monitoring Requirements, con’t.Radiation doses are monitored with either a

Luxel® OSL (Optically Stimulated Luminescence) whole body badge, or a TLD (Thermoluminescent dosimeter) extremity badge.

The devices are processed monthly or quarterly.Action levels have been set which trigger

investigations to determine if the exposures were as low as reasonably achievable.

If not, recommendations are made to ensure that future exposures are ALARA.

Conceptus Protection PolicyRecent studies have shown that the risk of childhood leukemia and

other cancers increases if the mother experienced a significant radiation exposure during pregnancy.

The N.C. regulations limit the dose of the conceptus to 500 mrem over the course of the pregnancy, if the worker declares her pregnancy in writing to the employer.

If an employee decides to declare her pregnancy, she should notify her supervisor who will arrange for her to meet with the Radiation Safety Officer to discuss possible precautions to limit radiation exposure.

The Radiation Safety Officer will review work assignments and radiation exposure history, and may recommend limitations in work assignment if necessary.

Radiation doses will be reviewed monthly.

If radioactive materials are used, the employee may also be placed on a periodic bioassay program.

X-Ray Equipment Operator QualificationsDiagnostic equipment (other than dental x-ray equipment) shall be

used under the direction or supervision of a qualified physician.

Only the following individuals are authorized to make radiographic (other than dental) and fluoroscopic exposures:

qualified physicians, engineering and physics staff members, technologists and radiation therapists who are ARRT-registered,

have graduated from an accredited educational program, or in-training for ARRT registration.

non-ARRT registered individuals may operator bone densitometry equipment but must meet established training requirements.

exceptions to the above requirements must be approved by the Radiation Safety Subcommittee (RSS).

Dental x-ray equipment shall only be used under the direction or supervision of a qualified physician or dentist.

Indications for Use

Examinations involving radiation should be requested by a Licensed Independent Practitioner (Physician, Dentist, Physician Assistant and Nurse Practitioner)

request should reflect the practitioners' knowledge of the clinical condition

exams should not be repeated merely for the practitioners' convenience

retakes may be performed upon the discretion of the qualified x-ray equipment operator or if requested by a LIP

Keep in mind - not exposing the patient gives the largest dose reduction.

Radiology Department Clinical Staff are available for consultation before and after diagnostic radiology examinations.

Guidelines for Safe Operation of X-Ray EquipmentPersonnel Monitoring: Wear only YOUR assigned monitoring

device Wear your device for the current time

period Return your device in a timely fashionOnly persons whose presence is necessary

should be in the radiographic or fluoroscopic room during exposures

Guidelines for Safe Operation of X-Ray Equipment, con’t.Protect all persons subject to direct scatter

radiation with whole body lead aprons (such as a skirt AND vest) or whole body protective barriers

Includes individuals using or around "mini" c-arms

A 0.25 mm lead equivalence apron reduces scattered x-rays by 95%

Shielding integrity of protective shielding devices is evaluated annually

Guidelines for Safe Operation of X-Ray Equipment, con’t.Operators must stand behind protective barriers

during radiographic exposures at permanent radiographic installations

Exemptions to this requirement - Cysto/Urology Suite Operator remains in the room during radiographic

exposure Wears a lead apron

DEXA equipment operators Remain at least 6 feet from the patient during

exposures, or as far away as practical due to room space limitations

Guidelines for Safe Operation of X-Ray Equipment, con’t.Make exposures with doors to the x-ray

room closed Exceptions include:

Corridor doors of the Dental Clinic Doors leading to the Tech Work Area of

Main Radiology Avoid making exposures when individuals

are in or near these doorways

Guidelines for Safe Operation of X-Ray Equipment, con’t.Holding Patients: Use mechanical supporting devices when a patient or cassette must

be held If a patient must be held by an individual:

Protect holders with appropriate shielding devices (such as a lead apron) Protect body part exposed to the primary x-ray with at least 0.5 mm lead

equivalence (lead glove, lead apron) The individual holding the patient should be a member of the patient's

family Do not use minors Do not use pregnant females

Operator shall provide appropriate instructions to the holder to maintain doses ALARA

No individual shall be used routinely for holding! Although necessary under exceptional circumstances, x-ray

equipment operators should not routinely hold patients

Guidelines for Safe Operation of X-Ray Equipment, con’t.Exposure Control and Technique Charts: Keep exposure to the patient minimal practical amount

consistent with clinical objectives Automatic Exposure Control (AEC) feature should be

appropriately utilized for all exposures when available If not available, manual techniques must be utilized

Technique Charts must be available for radiographic and dental units: Indicate set of exposure factors (kVp, mAs, SID) which normally

yield an optimal image for a body part of specific size and orientation

Consider using dose reduction techniques (like high tube potential (kVp) and low current (mA)), as long as image quality is not compromised

Guidelines for Safe Operation of X-Ray Equipment, con’t.Limitation of the Useful Beam: Collimate the x-ray beam to the smallest area

consistent with clinical requirements Align the beam accurately with the patient and image

receptor Use the smallest practical field sizes and shortest

exposure times Exception: long exposure times may be required for breathing

technique studies Position all individuals such that no part of their body

will be exposed to the useful beam unless protected by at least 0.5 mm lead equivalence lead apron or whole body protective barrier

Guidelines for Safe Operation of X-Ray Equipment, con’t.Gonadal Shielding: Used for potentially procreative patients during

radiographic procedures when the gonads are in the direct beam Except when clinical objectives would be compromised Never use as a substitute for careful patient positioning and

limitation of the beam Consider gonadal shielding when the gonads lie within close

proximity (2 inches) of the primary beam Using shielding for procedures with the primary beam >2

inches from the reproductive organs has minimal effect on patient dose It does reassure patients that consideration has been given to

protecting them from unnecessary radiation exposure

Guidelines for Safe Operation of X-Ray Equipment, con’t.Mobile Radiographic Equipment Procedures: Use mobile equipment only used when impractical to transfer

patients to permanent installations Operator of mobile equipment must ask individuals whose presence

is not required to leave the room until the exposure is complete It may not be possible for all individuals to leave the room in areas

such as the PACU or ED, however the operator is responsible for positioning individuals as far away as practical and protecting them in accordance with ALARA policy

Individuals subject to direct scatter radiation, including operators, must be protected by lead aprons or whole body protective barriers

The operator shall also: Stand as far as possible (at least 6 feet) from the x-ray tube head and the

nearest edge of the image receptor Give an audible warning before exposure is made

Pregnant or Potentially-Pregnant PatientsSpecial precautions, consistent with clinical needs, shall be

taken to minimize exposure of the embryo or fetus in patients known to be or suspected of being pregnant.

It is the responsibility of the referring physician to determine the pregnancy status of patients of childbearing age, and to write a note in the chart describing the indication for the study and confirming that this was discussed with the patient. Exceptions to this include any study involving body parts above the abdomen or below the hips.

When the x-ray procedure does not include the abdomen or pelvis of the pregnant or potentially-pregnant patient, the abdominal region should be shielded with at least 0.25 mm lead equivalence whenever feasible, and the examination performed without regard to pregnancy.

Pregnant or Potentially-Pregnant Patients, con’t.When the x-ray procedure includes the abdominal region of the

pregnant or potentially-pregnant patient, the examination shall not be performed without approval from the physician responsible for the procedure involving radiation. Written informed consent should be obtained for all procedures involving direct exposure of the conceptus and/or whenever conceptus dose is likely to exceed 1 rem and shall be obtained whenever dose to the conceptus is likely to exceed 5 rem.

Consent forms are available in English and Spanish. Procedures involving the abdomen or pelvis with the conceptus in the field of view that are likely to deliver a conceptus dose greater than 1 rem include, but are not limited to, CT, fluoroscopy in excess of 1 minute, and radiographic procedures requiring multiple imaging (>3) of the conceptus region.

Pregnant or Potentially-Pregnant Patients, con’t.Although it is the responsibility of the referring physician to determine

pregnancy status, those operating diagnostic x-ray equipment shall ask all patients of childbearing age whether or not they are pregnant and the date of their last menstrual period. This information is to be recorded prior to the procedure. When pregnancy status is unclear, or when the date of the last menstrual period is greater than two weeks (14 days), a urine pregnancy test must be performed to exclude pregnancy, unless the delay necessary to perform the pregnancy test would jeopardize the patient's health.

Radiation exposure must be used judiciously and kept to a minimum, and imaging techniques not involving radiation should be considered. The imaging techniques used, such as fluoroscopic time, kVp and mA, as well as the number of images taken and the abdominal thickness measurements are to be recorded. A radiation physicist should be contacted to assist with dose estimates. A formal dose calculation will be performed for procedures that are likely to deliver a conceptus dose in excess of 15 rem. Radiation Safety is available for consultation at 919-962-5507, Monday – Friday 8 am to 5 pm, and after-hours and on weekends and holidays by calling 919-962-6565 and asking to have Radiation Safety paged.

Fluoroscopy-Guided Interventional ProceduresA number of fluoroscopically-guided interventional procedures

are in use that have the potential for extended fluoroscopic time. The cumulative radiation entrance dose from these procedures can be sufficient to induce skin injuries (such as this one).

A thorough equipment quality control program can minimize or prevent these injuries. Including skin injury as one of the procedure risks in the patient consent form can inform the patient, prevent undue concern and promote early injury reaction and awareness.

The U.S. Food and Drug Administration has issued a public health advisory on the avoidance of x-ray induced skin injuries to patients. UNC Health Care adopts the principles of this advisory as a minimum injury prevention guide for all clinical services.

A full-text version is available here: Avoidance of Serious X-Ray-Induced Skin Injuries to Patients During Fluoroscopically-Guided Procedures

Fluoroscopy-Guided Interventional Procedures, con’t.The exposure rate used in fluoroscopy should be as low as is

consistent with the fluoroscopic requirements and should not normally exceed 10 R/min (measured in air) at the position where the beam enters the patient (in normal mode – high level mode must not exceed 20R/min).

It is usually best to operate fluoroscopic machines with the "automatic brightness system" engaged to optimize performance and minimize patient dose.

Fluoroscopy should not be used as a substitute for radiography but should be reserved for the study of dynamics or spatial relationships or for guidance in spot-film recording of critical details.

Medical fluoroscopy should be performed only by or under the immediate supervision of physicians or physician extenders properly trained in fluoroscopic procedures.

Fluoroscopy-Guided Interventional Procedures, con’t.Protective drapes may only be removed during procedures granted

a waiver for removal, and must be reattached immediately after the procedure.

The hand of the fluoroscopist should not be placed in the useful beam unless the beam is attenuated by the patient and a protective glove of at least 0.5 mm lead equivalent.

The hand of the fluoroscopist should not be placed in the useful beam unless the beam is attenuated by the patient and a protective glove of at least 0.5 mm lead equivalent.

In digital/image acquisition, take special care to limit patient exposure as this mode uses 8-10x higher tube currents than normal fluoroscopy.

Utilize pulsed or low-dose fluoroscopy whenever possible.

Record fluoroscopy time and/or reported patient dose for each procedure.

Important

Report any unusual or unsafe condition involving sources of radiation to the Radiation Safety Office immediately.

Radiation Safety is available during normal duty hours at 919-962-5507.

Radiation Safety can be reached after normal working hours through Campus Police at 919-962-6565.

Radioactive Materials licenses, x-ray registrations, regulations, inspection reports and exposure reports are available for review in the UNC Department of Environment, Health and Safety, Radiation Safety Section, 1120 Estes Drive Extension, CB# 1650, 919-962-5507.