radiation safety for x-ray equipment operators

ONLINE SELF-STUDY

Radiation 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 Terms

Terms 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 Terms

Terms 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 Assessment

Effects 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 System

The 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

http://ehs.unc.edu/radiation/

http://www.physics.isu.edu/radinf/lstintro.htm

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

http://www.ncradiation.net/

http://www.ncradiation.net/Xray/documents/engnoticeemp807.pdf

Basic Radiation Safety Practices

North 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 Practices

Time: 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

Requirements

The 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 Policy

Recent 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 Equipment

Personnel Monitoring:

Wear only YOUR assigned monitoring device

Wear your device for the current time period

Return your device in a timely fashion

Only persons whose presence is necessary should be

in the radiographic or fluoroscopic room during

exposures


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



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



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



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



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



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



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



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

Patients

Special 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.


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.


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

http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotifications/UCM063084

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.

radiation safety for x-ray equipment operators

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