Working in conjunction with their partners in other agencies, the FDA takes action to:
Promote safe use of medical imaging devices
Support informed clinical decision
Increase patient awareness
ALARA concept adopts an extremely conservative model with respect to the relationship between:
Ionizing radiation and potential risk
The main function of the Nuclear Regulatory Commission (NRC):
Oversee the nuclear energy industry
Run by the government of Japan, primarily studies Japanese atomic bomb survivors:
Radiation Effects Research Foundation
Functions and/or responsibilities of the United States Occupational Safety and Health Administration (OSHA):
Monitoring agency in places of employment, predominantly in industry
Responsible for regulations concerning an employee’s “right to know” with regard to hazards in the workplace
Effective dose (EfD) limit for the lens of the eye:
15 mSv
Occasional exposure for the purpose of education and training is permitted, provided that the annual effective dose limit of __ is not exceeded for persons under the age of 18 years.
1 mSv annually
Responsibilities of a health care facility’s radiation safety committee (RSC):
Provide guidance for the radiation safety program
Facilitate the ongoing operation of the radiation safety program
Effective dose (EfD) limits may be specified for:
Whole-body exposure
Partial-body exposure
Exposure of individual organs
If a dose of radiation produces a skin burn, a higher dose of radiation will cause the skin burn to be more severe; however, a dose below the threshold level for skin burn will:
not demonstrate the effect
The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) evaluates human and environmental ionizing radiation exposures from a variety of sources, including:
Radioactive materials
Radiation-producing machines
Radiation accidents
Epidemiologic studies of atomic bomb survivors exposed in utero have provided evidence of a dose-dependent increase in the incidence of intellectual disability for fetal doses greater than approximately:
0.4 Sv
The essential concept underlying radiation protection:
any organ in the human body is vulnerable to damage from exposure to ionizing radiation
Random effect of ionizing radiation
Stochastic event
Agency was previously known as the Atomic Energy Commission
Nuclear Regulatory Commission (NRC)
To provide a low-exposure cut-off level for negligible risk, agencies have established an annual negligible individual dose (NID) of __ .
0.01 mSv/year
A radiation safety officer in a health care facility must have sufficient authority, organizational freedom, and management prerogative to:
Identify radiation safety problems
Initiate, recommend, or provide corrective action
Stop unsafe operations involving by-product material
Verify implementation of corrective actions.
The responsibility for maintaining radiation monitoring records for all personnel and for providing counseling for individuals who receive monitor readings in excess of allowable limits:
Radiation safety officer
Upper boundary radiation exposure limits for occupationally exposed persons are associated with risks that are similar to other industries, which include:
Manufacturing
Trade
Government
Health care facilities usually adopt investigation levels, defined as level I and level II. In the United States, these levels are traditionally __ to __ the applicable regulatory standards
1/10 to 3/10
Common reasons for unacceptable images:
Patient mispositioning
Incorrect centering of the radiographic beam
Patient motion during the radiographic exposure
Incorrect collimation of the radiographic beam
Involuntary motions that cannot be willingly controlled
Chills Tremors Muscle spasms Pain Active withdrawal
Lack of control over voluntary motion may be attributed to:
The patient’s age Breathing patterns or problems Physical discomfort Fear of the examination Mental instability
The first step in protection of the reproductive organs:
Precise collimation of the radiographic beam to include only the anatomy of interest
Areas of the body that should be shielded from the useful beam whenever possible:
Lens of the eye
Breasts
Thyroid gland
Reproductive organs
Benefits of a repeat analysis program:
Increased awareness among radiographers of the need to produce optimal quality recorded images
Radiographers become more careful in producing radiographic images
In-service education programs covering these specific topics may be designed for imaging personnel
If a pregnant patient is inadvertently irradiated:
Radiation safety officer (RSO) or the medical physicist should perform the calculations necessary to determine fetal dose
Frequently a problem in diagnostic pediatric radiography:
Patient motion
A type of gonadal shield that provides maximal gonadal protection for a male patient when AP, oblique, and lateral projections:
Shaped contact shield containing 1 mm of lead
Examples of nonessential radiographic examinations:
A chest x-ray examination automatically scheduled on admission to the hospital
Lumbar spine x-ray examination as part of a pre-employment physical
Whole-body computed tomography (CT) screening
When a properly calibrated automatic exposure control (AEC) is not employed:
Use standardized technique charts that have been established for each x-ray unit
Because multiple bony areas span the entire body, the radiation dose absorbed by the organ called bone marrow:
Cannot be measured by a direct method; it can only be estimated
Damage to the newborn is unlikely for doses below
0.2 Gy
Reducing the field size to the anatomic features of interest:
Reduces patient exposure
Increases recorded image quality by decreasing scatter
The genetically significant dose (GSD) for the population of the United States is approximately:
0.20 mSv
Specific area shielding may be selectively used during some x-ray procedures to protect:
Reproductive organs
Lens of the eye
Breast tissue
Effective means to limit the patient’s exposure to ionizing radiation:
Utilize appropriate radiation reduction techniques
Use protective devices that minimize radiation exposure
Select higher kVp and lower mAs
Sensing devices most often used to measure skin dose directly:
Thermoluminescent dosimeters
Neglecting to use standardized technique charts may result in:
Poor-quality image
Repeat examinations
Unnecessary exposure of the patient
Diagnostic medical procedures result in fetal exposures of less than:
0.01 Gy, the risk of abnormality is very small
Analysis of radiographic repeat rates provide what type of benefits:
Provides information for process improvement
Helps minimize patient exposure
Improves overall performance of the imaging department.
What effect does a repeat image have on the radiation dose received by the patient?
The patient’s skin and possibly the gonads receive a double radiation dose
Alternate term for use factor (U):
Beam direction factor
The dose rate to personnel located within a meter of the patient during a c-arm procedure compares to routine fluoroscopy:
C-arm and routine fluoroscopy are comparable in dose rates
Determines the shielding requirements for a particular imaging facility:
Medical physicist
Because exposure from radiation-related jobs will not alter the __, radiation workers may receive a larger equivalent dose than members of the general population.
genetically significant dose
X-rays scattered from the patient’s body should scatter a minimum of ____ times before reaching a controlled area.
2
If the peak energy of the x-ray beam is 100 kVp, a protective lead apron must be the equivalent to at least:
0.25-mm thickness of lead
The radiation output weighted time that the unit is actually delivering radiation during the week:
Workload
Protective eyeglasses fitted with optically clear lenses that contain a minimal lead equivalent protection level should be _____ thick.
0.35 mm
The lifetime effective dose in mSv should not exceed:
10 times the occupationally exposed person’s age in years
Radiation-shielding design considerations:
The mean energy of the x-rays that will strike the barrier
Whether the barrier is of a primary or secondary nature
The workload of the unit
The use factor of the unit
The occupancy factor behind the barrier
Part(s) of a diagnostic x-ray unit that should not be touched while a radiographic exposure is in progress:
Tube housing
Collimator
High-tension cables
Diagnostic imaging personnel routinely receive the highest occupational exposure during the following procedures:
Fluoroscopy
Mobile radiography
X-ray special procedures (Interventional radiography)
The maximum weekly permitted equivalent dose for a controlled area:
1 mSv
The intensity of the x-ray beam is inversely proportional to the square of the distance from the source, how does the intensity of the x-ray beam change when the distance from the source of radiation and a measurement point is tripled?
Decreases by a factor of 9 at the new distance
The intensity of the x-ray beam is inversely proportional to the square of the distance from the source.
Inverse square law
Adjustments in technical exposure factors that decrease the production of scattered radiation:
Increase kVp and decrease mAs accordingly
X-ray examinations when a radiographer wear a thyroid shield:
Fluoroscopy and x-ray special procedures
Term that represents a portion of beam-on time that the x-ray beam is directed at a primary barrier during the week:
Use factor
Appropriate steps when a radiologic technologist declares her pregnancy to her employer:
She continues to perform her duties without interruption of employment
She receives radiation safety counseling
She follows established radiation safety practices
Secondary radiation includes:
Leakage radiation
Scatter radiation
A protective curtain with a minimum of 0.25-mm lead equivalent, should normally be positioned between the fluoroscopist and the patient to intercept which type radiation?
Scatter radiation
X-ray procedures that increase the radiographer’s risk of exposure to ionizing radiation:
Mobile C-arm fluoroscopy
Interventional procedures that use high level control fluoroscopy
Mobile radiographic examinations
When scattered radiation decreases, the radiographer’s exposure:
Decreases
When the time spent in a higher radiation area is reduced or limited, occupational exposure:
Decreases
The annual effective dose limit for individual members of the general population not occupationally exposed is __ from artificial sources other than medical irradiation and natural background and __ for infrequent annual exposure
1 mSv
5 mSv
