Radiation Protection Flashcards
What is used to account for the differences in tissue sensitivity to ionizing radiation when determining effective dose E?
Tissue Weighing Factor
According to the National Council on Radiation Protection and Measurements (NCRP), the monthly gestational dose-equivalent limit for embryo/fetus of a pregnant radiographer is
5 mSv
A time of 1.5 minutes is required for a particilar fluoroscopic examination, whose exposure rate is 275 mR/h. What is the approximate radiation exposure for the radiologic staff present in the fluoroscopy room during the examination?
6.87 mR
275(mR) = x (mR)
———— ———-
60 (min) 1.5 (min)
60x = 412.5 x = 6.87 mR dose in 1.5 mins
If the exposure rate to an individual standing 4m from a source of radiation is 10mR/h, what will be the dose received after 20 minutes at a distance of 6m from the source?
1.48 mR
I1 = D2(2) --- -------- I2 D1(2)
10 = 36
— —-
x 16
36x = 160
x = 4.44
All the ff statements regarding the mobile radiographic equipment are true except
exposure switches must be the two-stage type
- the exposure cord must permit the operator to stand at least 6 ft from the px, x-ray tube, and useful beam
- a lead apron should be carried with the unit and worn by the radiographer during exposure
- the radiographer must alert individuals in the area before making the exposure
Which of the ff cell types has the greatest radiosensitivity in the adult human?
Lymphocytes
Guidelines for the use of protective shielding state that gonadal shielding should be used
- if the patient has reasonable reproductive potential
* when the gonads are within 5cm of the collimated field
The interaction between ionizing radiation and the target molecule taht is most likely to occur is the
indirect effect
What is the approximate entrance skin exposure (ESE) for the average AP supine abdomen radiograph?
300 mrad
All of the ff device(s) are generally used to help reduce patient dose except
grid
How will xray photon intensity be affected if the source-to-image distance (SID) is doubled?
Its intensity decreases four times
What is the established annual occupational dose-equivalent limit for the lens of the eye?
150mSv
Occupational radiation monitoring is required when it is possible that the individual might receive more than
one-tenth the annual dose
Sources of natural background radiation contributing to whole body radiation dose include
- terrestrial radionuclides
* internal radionuclides
Irradiation of water molecules within the body and their resulting breakdown is termed
radiolysis
Which of the ff contributes most to occupational exposure?
Compton scatter
Which of the ff is (are) used to account for the differences in tissue characteristics when determining effective dose to biologic material?
Tissue Weighing Factor
The x-ray interaction with the matter that is responsible for the majority of scattered radiation reaching the IR is
Compton scatter
The exposure rate to a body 4 ft from a source of radiation is 16R/h. What distance from the source would be necessary to decrease the exposure to 6R/h?
7 ft
16 R/h = X2
--------- ----
6 R/h 16
6x(2) = 256
x(2) = 42.66
With milliamperes (mA) increased to maintain output intensity, how is the ESE affected as the SSD is increased?
The ESE increases
Late radiation-induced somatic effects include
- thyroid cancers
- cataractogenesis
- genetic mutations
Each time an x-ray beam scatters, its intensity at 1 m from the scattering object is what fraction of its original intensity?
1/1000
According to NCRP, the annual occupational whole-body dose-equivalent limit is
50 mSv
A thermoluminiscent dosimetry system would use which of the following crystals?
Lithium fluoride
Sources of secondary radiation include
- background radiation
- leakage radiation
- scatterred radiation
leakage radiation & scaterred radiation
All the following have an effect on patient dose except
focal spot size
- kilovoltage
- milliampere-seconds
- inherent filtration
The photoelectric effect is more likely to occur with
- absorbers having a high Z number
- high-energy incident photons
- positive contrast media
absorbers having high Z number
positive contrast media
All the ff radiation-exposure responses exhibit a nonlinear threshold dose-response relationship except
leukemia
- skin erythema
- hematologic depression
- radiation lethality
In radiation protection, the product of absorbed dose and the correct modifying factor (radxQF) is used to determine
rem (Sv)
Which of the ff is recommended for the pregnant radiographer
Wear a second dosimeter under the lead apron
The annual dose limit for medical imaging personnel includes radiation from
- occupational exposure
- background radiation
- medical x-rays
occupational exposure
Which of the ff anomalies is (are) possible if an exposure dose of 40 rad (400mGy) were delivered to a pregnant uterus in the third week of pregnancy?
Organ anomaly
The effects of radiation on biologic material depend on several factors. If a quantity of radiation is delivered to a body over a long period of time, the effect
will be less than if it were delivered all at one time
Medical and dental radiation accounts for what percentage of the general public’s exposure to human-made radiation?
90%
Which of the ff is (are) composed of nondividing, differentiated cells?
- neurons and neuroglia
- epithelial tissue
- lymphocytes
neurons and neuroglia
How does filtration affect the primary beam?
It increases the average energy of the primary beam.
What is the minimum lead requirement for lead apron, according to the NCRP?
0.50 mm Pb
An optically stimulated luminescence dosimeter contains which of the ff detectors?
Aluminum oxide
Immature cells are referred to as
- undifferentiated cells
* stem cells
What is the term used to describe x-ray photon interaction with matter and the transference of part of the photon’s energy to mater?
Scattering
What is the approximate ESE for the average upright PA chest radiograph using 115 kVp and a grid?
20 mrad
To be in compliance with the radiation safety standards, the fluoroscopy exposure switch must
terminate fluoro after 5 mins
Primary radiation barriers must be at least how high?
7 ft
The annual dose limit for occupationally exposed individuals is valid for
beta, x-, and gamma radiations
Patient dose increases as fluoroscopic
FOV decreases
Types of gonadal shielding include which of the ff?
- flat contact
- shaped contact (contour)
- shadow
all of them
What unit of measure is used to express ionizing radiation dose to biologic material?
Rem (Sv)
LET is best defined as
- a method of expressing radiation quality
* a measure of the rate at which radiation energy is transferred to soft tissue
For exposure to 1 rad of each of the ff ionizing radiations, which would result in the greatest dose to the individual?
c
For exposure to 1 rad of each of the ff ionizing radiations, which would result in the greatest dose to the individual?
Internal source of alpha particles
The skin response to radiation exposure that appears as hair loss is known as
epilation
Biologic material is least sensitive to irradiation under which of the ff conditions?
Anoxic
The reduction in the intensity of an xray beam as it passes through the material is termed?
attenuation
Which type of dose-response relationship represents radiation-induced leukemia and genetic effects?
Linear, nonthreshold
A dose of 25 rad to the fetus during the seventh or eighth week of pregnancy is likely to cause which of the ff?
Neurologic anomalies
Late effects of radiation, whose incidence is dose related and for which there is no threshold dose, are referred to as
stochastic
Which of the ff methods can be used to reduce radiation exposure to a recently fertilized ovum?
Elective booking
Patient questionnaire
The 10-day rule
Classify the ff tissues in order of increasing radiosensitivity:
- Liver cells
- Intestinal crypt cells
- Muscle cells
3, 1, 2
The largest amount of diagnostic xray absorption is most likely to occur in which of the ff tissues?
Bone
According to NCRP regulations, leakage radiation from the x-ray tube must not exceed
100mR/h
Which of the ff most effectively minimizes the radiation exposure to the patient?
High speed intensifying screen
Which of the ff statements is (are) true with respect to radiation safety in fluoroscopy?
- Tabletop radiation intensity must not exceed 2.1 R/min/mA
- Tabletop radiation intensity must not exceed 10 R/min
- In high-level fluoroscopy, tabletop intensity up to 20 R/min is permitted.
all of the above
The symbol 130/56 Ba and 138/56 are examples of which of the ff?
isotopes
Which of the ff account(s) for an x-ray beam’s heterogenecity?
All of the above
Which of the ff factors will affect both the quality and the quantity of the primary beam?
- HVL
- kV
- mA
HVL and kV
Diagnostic x-radiation may be correctly described as
low energy, low LET
Primary radiation barriers usually require which thickness of shielding?
1/16-in. lead
Which of the following groups of exposure factors will deliver the least patient dose? 300 mA, 250 ms, 70 kVp 300 mA, 125 ms, 80 kVp 400 mA, 90 ms, 80 kVp 600 mA, 30 ms, 90 kVp
600 mA, 30 ms, 90 kVp
For radiographic examinations of the skull, it is generally preferred that the skull be examined in the
PA Projection
According to the NCRP, the annual occupational dose-equivalent limit (50 rem) to the thyroid, skin, extremities is
500 mSv
The skin response to radiation exposure, which appear as reddening of the irradiated skin area, is known as
erythema
What is the intensity of scattered radiation perpendicular to and 1 m from a patient compared with the useful beam at the patient’s surface?
0.1%
An increase of 1.0 mm added aluminum filtration of the x-ray beam would have which of the ff effects?
- Increase in average energy of the beam
- Increase in patient skin dose
- Increase in milliroentgen output
Increase in average energy of the beam
Aluminum filtration has its greatest effect om
low energy xray photons
The amount of time that xrays are being produced and directed toward a particular wall is referred to as the
Use factor
The operation of personnel radiation monitoring devices can depend on which of the ff
- Ionization
- Luminescence
- Thermoluminescence
all of them
Which of the ff results from restriction of the xray beam?
- Less scattered radiation production
- Less patient hazard
- Less radiographic contrast
1 & 2
Which acute radiation syndrome requires the largest exposure before any effects become apparent?
CNS
Early symptoms of acute radiation syndrome include
- leukopenia
- nausea and vomiting
- cataracts
1 & 2
The unit of measurement used to express occupational exposure is the
rem (Sv)
Possible responses to irradiation in utero include
- spontaneous abortion
- congenital anomalies
- childhood malignancies
all of them
The Bucky slot cover is in place to protect the
- patient
- fluoroscopist
- technologist
2 & 3
Which type of personnel radiation monitor can provide an immediate reading?
Ionization Chamber
Which of the following terms is correctly used to describe xray beam quality
HVL
The most efficient type of male gonadal shielding for use during fluoroscopy is
shape contact (contour)
Isotopes are atoms that have the same
atomic number but different mass number
If the ESE for a particular exposure is 25mrad, what will be the intensity of the scattered beam perpendicular to and 1 m from the patient?
0.025 mrad
The likelihood of adverse radiation effects to any radiographer whose dose is kept below the recommended guideline is
very remote
Factors that contribute to the amount of scattered radiation produced include
- radiation quality
- field size
- grid ratio
1 & 2
The SSD in mobile fluoroscopy must be
a minimum of 12 in
The automatic exposure device that is located immediately under the xray table is the
ionization chamber
The law of Bergonie and Tribondeau states that cells are more radiosensitive if they are
- highly proliferative
- highly differentiated
- immature
1 & 3
It is necessary to question a female patient of childbearing age regarding her
1 & 2
What is the effect on RBE as LET increases?
as LET increases, RBE increases
Which of the ff would most likely result in the greatest skin dose?
Short SID
Which of the ff radiation-induced conditions is most likely to have the longest latent period?
Leukemia
Which of the ff ionizing radiations is described as having an RBE of 1.0?
diagnostic xrays
If an individual receives 50mR while standing 4 ft from a source of radiation for 2 minutes, which of the ff options will most effectively reduce his or her radiation exposure to that source of radiation?
standing 8 ft from the source of radiation
The most radiosensitive portion of the GI tract is
small bowel
How do the fractionation and protraction affect radiation dose effects?
- They reduce the effect of radiation exposure
- They permit cellular repair
- They allow tissue recovery
all of them
The photoelectric effect is an interaction between an x-ray photon and
an inner shell electron
Filters used in radiographic x-ray tubes generally are composed of
aluminum
All the ff function to reduce patient dose except
a high speed grid
- beam restriction
- high kVp, low mAs factors
- a high-speed imaging system
In the production of Bremsstrahlung radiation
the incident electron is defelcted, with resulting energy loss
An increase in toatal filtration of the xray beam will increase
beam HVL
Which of the ff is considered the unit of exposure in air?
Roentgen (C/kg)
The purpose of filters in a film badge is
to measure radiation quality
How many HVLs are required to reduce the intensity of a beam of monoenergetic photons to less than 15% of its original value?
3
Which of the ff has (have) an effect on the amount and type of radiation-induced tissue damage?
All of them
Radiation dose to personnel is reduced by which of the ff exposure control cord guidelines?
- Exposure cords on fixed equipment must be very short
- Exposure cords on mobile equipment should be fairly long
- Exposure cords on fixed and mobile equipment should be of the coiled, expandable type
1 & 2
Any wall that the useful xray beam can be directed toward is called a
primary barrier
Which of the ff body parts is (are) included in whole-body dose?
1 & 2
Which of the ff projections would deliver the largest thyroid dose?
AP skull
Which of the ff personnel monitoring devices used in diagnostic radiography is considered to be the most radiosensitive and accurate?
OSL dosimeter
Irradiation of macromolecules in vitro can result in
- main-chain scission
- cross-linking
- point lesions
All of them
Which of the ff radiation situations is potentially the most harmful?
A large dose to the whole body all at one time
How much protection is provided from a 100-kVp beam when using a 0.50 mm lead-equivalent apron?
75%
Occupational radiation monitoring is required when it is likely that an individual will receive more than what fraction of the annual dose limit?
1/10
Which of the ff statements regarding the pregnant radiographer (are) true?
- She should declare her pregnancy to her supervisor.
- She should be assigned a second personnel monitor.
- Her radiation history should be reviewed.
1, 2, and 3
Examples of late effects of ionizing radiation on humans include
- leukemia
- local damage tissue
- malignant disease
all of them
Which of the ff cells are the most radiosensitive?
Erythroblasts
What is (are) the major effect(s) of deoxyribonucleic acid (DNA) irradiation?
- Malignant disease
- Chromosome Aberration
- Cell death
all of them
Which of the ff contributes most to patient dose?
The photoelectric effect
If an exposure dose of 50mR/hr is delivered from a distance of 3 ft, what would be the dose delivered after 20minutes at a distance of 5 ft from the source?
a
The classifications of acute radiation syndrome include all the ff except
neonatal
- CNS
- gastrointestinal
- hematologic
In the production of characteristic radiation at the tungsten target, the incident electron
ejects an inner-shell tungsten electron
Which of the ff defines the gonadal dose that, if receive by every member of the population, would be expected to produce the same total genetic effect on that population as the actual doses received by each of the individuals?
Genetically significant dose
If an exposure dose of 50mR/hr is delivered from a distance of 3 ft, what would be the dose delivered after 20minutes at a distance of 5 ft from the source?
6 mR
The term effective dose refers to
whole-body dose
Which of the ff is (are) possible long-term somatic effects of radiation exposure?
- Blood changes
- Cataractogenesis
- Embryologic effects
1 & 2
The operation of personal radiation monitoring can be based on stimulated luminescence. Which of the ff personal radiation monitors function(s) in that manner?
- OSL dosimeter
- TLD
- Pocket dosimeter
1 & 2
If a patient received 1,400 mrad during a 7-minute fluoroscopic examination, what was the dose rate?
0.2 rad/min
Biologic material irradiated under hypoxic conditions is
less sensitive than when irradiated under oxygenated conditions
Which interaction between ionizing radiation and the target molecule involves formation of a free radical?
Indirect effect
The single most important scattering object in both radiography and fluoroscopy is the
patient
All the ff statements regarding TLDs are true except
after xray exposure, TLDs emit heat in response to stimulation by light
A student radiographer who is under 18 years of age must not receive an annual occupational dose of greater than
0.1 rem (1mSv)
What is the approximate ESE for the average AP lumbar spine radiograph?
300 mrad
Which of the ff is (are) likely to improve image quality and decrease patient dose?
- Beam restriction
- Low kilovolt and high microampere-second factors
- Grids
beam restriction
Types of secondary radiation barriers include
- the control booth
- lead aprons
- the xray tube housing
all of them
Lead aprons are worn during fluoroscopy to protect the radiographer from exposure to radiation from
Compton scatter
Types of structural damage to a DNA molecule by ionizing radiation include which of the ff?
1, single-side-rail scission
2. double-side-rail scission
3. Cross-linking
all of them
Which of the ff can be an effective means of reducing radiation exposure?
- Barriers
- Distance
- Time
all of them
The effects of radiation on biologic material depend on several factors. If a large quantity of radiation delivered to a body over a short period of time, the effect
will be greater than if it were delivered in increments
Somatic effects of radiation refer to effects that are manifested
during the life of the exposed individual
What minimum total amount of filtration (inherent plus added) is required in xray equipment operated above 70kVp?
2.5 mm Al equivalent
The dose of radiation that will cause a noticeable skin reaction is referred to as the
SED
The NCRP recommends an annual effective occupational dose-equivalent limit of
5 rem (50mSv)
Some patients, such as infants and children, are unable to maintain the necessary radiographic position without assistance. If mechanical restraining devices cannot be used, which of the ff should be requested or permitted to hold the patient?
Patient’s father
A controlled area is defined as one
- that is occupied by people trained in radiation safety
- that is occupied by people who wear radiation monitors
- whose occupancy factor is 1
all of them
Which of the ff terms refers to the period between conception and birth?
Gestation
Somatic effects resulting from radiation exposure can
- have possible consequences on the exposed individual
- have possible consequences on future generations
- cause temporary infertility
1 and 3
How does the use of rare earth intensifying screens contribute to lowering the patient dose?
- it permits the use of lower milliampere-seconds
- it permits the use of lower kilovolts peak (kVp)
- It eliminates the need for patient shielding
1 only
In which type of monitoring device do photons release electrons by their interaction with air?
Pocket dosimeter
The advantages of beam restriction include which of the ff?
- Less scattered radiation is produced.
- Less biologic material is irradiated.
- Less total filtration will be necessary.
1 & 2 only
The person responsible for ascertaining that all radiation guidelines are adhered to and that personnel understand and employ radiation safety measures is the
radiation safety officer
The dose-response curve that apears to be valid for genetic and some somatic effects is the
- linear
- nonlinear
- nonthreshold
1 & 3
Which of the ff statements regarding the human gonadal cells is (are) true?
- the female oogonia reproduce only during fetal life.
- The male spermatogonia reproduce continously.
- both female and male stem cells reproduce only during fetal life.
1 & 2
Protective devices such as lead aprons funtion to protect the user from
- scatter radiation
- the primary beam
- remnant radiation
1 only
The primary function of filtration is to reduce
patient skin dose
Which of the ff factors can affect the amount or the nature of radiation damage to biologic tissue?
- Radiation quality
- Absorbed dose
- Size of irradiated area
all of them
Examples of stochastic effects of radiation exposure inlude
- radiation induced malignancy
- genetic effects
- leukemia
all of them
Which of the ff tissues is (are) considered to be particularly radiosensitive?
- Intestinal mucuos membrane
- Epidermis of extremities
- Optic nerves
1 only
Which of the ff groups of exposure factors will deliver the least amount of exposure to the patient?
400 mA, 0.25 second, 100 kVp
- 600 mA, 0.33 second, 90 kVp
- 800 mA, 0.5 second, 80 kVp
- 800 mA, 1.0 second, 70 kVp
Stochastic effects of radiation are those that
- have a threshold
- may be described as “all-or-nothing” effects
- are late effects
2 & 3
To within what percentage of the SID must the collimator light and actual irradiated area be accurate?
2%
Under what circumstances might a radiographer be required to wear two dosimeters?
- During pregnancy
- While performing vascular procedures
- While performing mobile radiography
1 & 2 only
What quantity of radiation exposure to the reproductive organs is required to cause temporary infertility?
200 rad
Which of the ff personnel radiation monitors will provide an immediate reading?
Pocket dosimeter
The tabletop exposure rate during fluoroscopy shall not exceed
10 R/min
Which of the ff refers to a regular program of evaluation that ensures the proper functioning of xray equipment, thereby protecting both radiation workers and patients?
c
If the exposure rate at 3 ft from the fluoroscopic table is 40 mR/h, what will be the exposure rate for 30 minutes at a distance of 5 ft from the table?
7 mR
Which of the ff rdiation protection measures is (are) appropriate for mobile radiography?
- The radiographer must be at least 6 ft from the px and the xray tube during the exposure
- The radiographer must announce in a loud voice that an exposure is about to be made and wait for personnel, visitors and patients to temporarily leave the area.
- The radiographer must try to use the shortest practical SID.
1 & 2 only
Radiation that passes through the tube housing in directions other than taht of the useful beam is termed
leakage radiation
The presence of ionizing radiation may be detected in which of the following ways?
- Ionizing effect on air
- Photographic effect on film emulsion
- Fluorescent effect on certain crystals
all of them
Which of the ff refers to a regular program of evaluation that ensures the proper functioning of xray equipment, thereby protecting both radiation workers and patients?
Quality assurance
What should be the radiographer’s main objective regarding personal radiation safety?
to keep personal exposure as far below the dose limit as possible
Which of the ff safeguards is (are) taken to prevent inadvertent irradiation in early pregnancy?
- Patient postings
- Patient questionnaire
- Elective booking
d
If the exposure rate to a body standing 7 ft from a radiation source is 140 mR/h, what will be the dose to that body at a distance of 8 ft from the source in 30 mins?
53.6 mR
Which of the ff types of radiation is (are) considered electromagnetic?
- Xray
- Gamma
- Beta
1 and 2 only
Which of the ff features of fluoroscopic equipment is (are) designed epecially to eliminate unnecessary radiation exposure to the patient and/or personnel?
- Bucky slot cover
- Exposure switch/foot pedal
- Cumulative exposure timer
all of them
Radiation output from a diagnostic xray tube is measured in which of the ff units of measurement?
Roentgen
Which of the ff is (are) considered especially radiosensitive tissues?
- Bone marrow
- Intestinal crypt cells
- Erthroblasts
All of them
Which of the ff safeguards is (are) taken to prevent inadvertent irradiation in early pregnancy?
- Patient postings
- Patient questionnaire
- Elective booking
All of them
The interaction between xray photons and tissue that is responsible for radiographic contrast but that also contributes significantly to patient dose is
the photoelectric effect
Which of the ff is (are) acceptable way(s) to monitor the radiation exposure of those who are occupationally employed?
- TLD
- OSL Dosimeter
- Quarterly blood cell count
1 & 2 only
The genetic dose of radiation borne by each member of the reproductive population is called the
genetically significant dose
According to NCRP, the pregnant radiographer’s gestational dose equivalent limit for a 1-month period is
0.5 mSv
Which of the ff projections is most likely to deliver the largest dose to the ovaies?
AP abdomen, 80 kVp
The correct way(s) to check for cracks in lead aprons is (are)
- to fluoroscope them once a year
- to radiograph them at low kilovoltage twice a year
- by visual inspection
1 only
The target theory applies to
DNA molecules
Which of the ff is (are) features of fluoroscopic equipment designed especially to eliminate unnecessary radiation to patient and personnel?
- Protective curtain
- Filtration
- Collimation
all of them
Which of the ff has (have) been identified as source(s) of radonexposure?
- Indoors, in houses
- Smoking cigarettes
- Radiology departments
1 & 2 only
What is the relationship between LET and RBE?
As LET increases, RBE increases
The biologic effect on an individual depends on which of the ff?
- Type of tissue interaction(s)
- Amount of interactions
- Biologic differences
All of them
