Nuclear Medicine Radiation Safety
Exam Questions with Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of the ALARA principle in a nuclear medicine
facility?
A. To eliminate all radiation exposure
B. To increase administered activity for every procedure
C. To keep radiation exposures as low as reasonably achievable
D. To replace regulatory dose limits
Rationale: ALARA means “as low as reasonably achievable.” It requires radiation
exposure to be minimized while still accomplishing the necessary clinical or
occupational task.
2. Which of the following is one of the three fundamental methods of reducing
external radiation exposure?
A. Increasing exposure time
B. Increasing distance from the radiation source
C. Increasing radionuclide activity
D. Removing shielding
Rationale: The basic radiation-protection principles are time, distance, and
shielding. Increasing distance generally reduces exposure rate, while minimizing
time and using appropriate shielding further reduce exposure.
,3. If the distance from a point radiation source is doubled, the exposure rate is
approximately:
A. Doubled
B. Unchanged
C. Reduced by half
D. Reduced to one-fourth
Rationale: For a point source, exposure rate follows the inverse-square
relationship. Doubling the distance reduces the exposure rate to approximately
one-fourth of its original value.
4. Which type of shielding is commonly used for high-energy gamma radiation in
nuclear medicine?
A. Cotton
B. Acrylic only
C. Lead or another suitable high-density shielding material
D. Paper
Rationale: High-density materials such as lead can substantially attenuate
penetrating gamma radiation. Shielding selection should be based on the
radionuclide energy and applicable radiation-protection requirements.
5. Which unit is used in the SI system to describe radioactive activity?
A. Gray
B. Sievert
C. Coulomb per kilogram
D. Becquerel
Rationale: The becquerel (Bq) is the SI unit of radioactive activity and represents
one nuclear transformation per second.
6. Which quantity describes the energy deposited by ionizing radiation per unit
mass of material?
,A. Activity
B. Exposure
C. Absorbed dose
D. Half-life
Rationale: Absorbed dose is the amount of radiation energy deposited per unit
mass and is expressed in gray (Gy) in the SI system.
7. Which SI unit is used for equivalent and effective dose?
A. Becquerel
B. Gray
C. Sievert
D. Curie
Rationale: The sievert (Sv) is used for quantities that account for radiation type
and, depending on the quantity, tissue sensitivity.
8. Which biological effect is generally considered stochastic?
A. Skin erythema at a high dose
B. Tissue necrosis
C. Cataract formation above a tissue threshold
D. Radiation-induced cancer
Rationale: Stochastic effects are probabilistic effects for which the likelihood
increases with radiation dose. Cancer induction is a principal example.
9. Which characteristic is associated with a deterministic tissue reaction?
A. No dose relationship
B. A threshold dose below which the effect is not expected to occur
C. A completely random occurrence independent of dose
D. An effect that occurs only from internal contamination
, Rationale: Tissue reactions, historically called deterministic effects, generally have
a threshold. Above the threshold, severity tends to increase with increasing dose.
10. Which occupational practice most directly reduces radiation exposure to a
nuclear medicine technologist during dose preparation?
A. Holding the syringe by hand without shielding
B. Increasing the time spent near the dose
C. Using appropriate syringe shielding and minimizing handling time
D. Standing closer to the source
Rationale: Shielding and reduced handling time decrease external exposure.
Appropriate tools and shielding should be selected according to the radionuclide
and task.
11. What is the primary purpose of a personnel dosimeter?
A. To measure the patient's administered activity
B. To identify radionuclides
C. To monitor an individual's occupational radiation exposure
D. To calibrate a gamma camera
Rationale: Personnel dosimeters provide a record of occupational radiation
exposure and help identify unusual or excessive exposures that may require
investigation.
12. Where should a whole-body personnel dosimeter generally be worn when a
lead apron is not required?
A. Inside a radiation-shielded cabinet
B. At the location specified by the facility's dosimetry policy, typically on the
torso
C. On the floor
D. Inside the dose calibrator
Exam Questions with Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of the ALARA principle in a nuclear medicine
facility?
A. To eliminate all radiation exposure
B. To increase administered activity for every procedure
C. To keep radiation exposures as low as reasonably achievable
D. To replace regulatory dose limits
Rationale: ALARA means “as low as reasonably achievable.” It requires radiation
exposure to be minimized while still accomplishing the necessary clinical or
occupational task.
2. Which of the following is one of the three fundamental methods of reducing
external radiation exposure?
A. Increasing exposure time
B. Increasing distance from the radiation source
C. Increasing radionuclide activity
D. Removing shielding
Rationale: The basic radiation-protection principles are time, distance, and
shielding. Increasing distance generally reduces exposure rate, while minimizing
time and using appropriate shielding further reduce exposure.
,3. If the distance from a point radiation source is doubled, the exposure rate is
approximately:
A. Doubled
B. Unchanged
C. Reduced by half
D. Reduced to one-fourth
Rationale: For a point source, exposure rate follows the inverse-square
relationship. Doubling the distance reduces the exposure rate to approximately
one-fourth of its original value.
4. Which type of shielding is commonly used for high-energy gamma radiation in
nuclear medicine?
A. Cotton
B. Acrylic only
C. Lead or another suitable high-density shielding material
D. Paper
Rationale: High-density materials such as lead can substantially attenuate
penetrating gamma radiation. Shielding selection should be based on the
radionuclide energy and applicable radiation-protection requirements.
5. Which unit is used in the SI system to describe radioactive activity?
A. Gray
B. Sievert
C. Coulomb per kilogram
D. Becquerel
Rationale: The becquerel (Bq) is the SI unit of radioactive activity and represents
one nuclear transformation per second.
6. Which quantity describes the energy deposited by ionizing radiation per unit
mass of material?
,A. Activity
B. Exposure
C. Absorbed dose
D. Half-life
Rationale: Absorbed dose is the amount of radiation energy deposited per unit
mass and is expressed in gray (Gy) in the SI system.
7. Which SI unit is used for equivalent and effective dose?
A. Becquerel
B. Gray
C. Sievert
D. Curie
Rationale: The sievert (Sv) is used for quantities that account for radiation type
and, depending on the quantity, tissue sensitivity.
8. Which biological effect is generally considered stochastic?
A. Skin erythema at a high dose
B. Tissue necrosis
C. Cataract formation above a tissue threshold
D. Radiation-induced cancer
Rationale: Stochastic effects are probabilistic effects for which the likelihood
increases with radiation dose. Cancer induction is a principal example.
9. Which characteristic is associated with a deterministic tissue reaction?
A. No dose relationship
B. A threshold dose below which the effect is not expected to occur
C. A completely random occurrence independent of dose
D. An effect that occurs only from internal contamination
, Rationale: Tissue reactions, historically called deterministic effects, generally have
a threshold. Above the threshold, severity tends to increase with increasing dose.
10. Which occupational practice most directly reduces radiation exposure to a
nuclear medicine technologist during dose preparation?
A. Holding the syringe by hand without shielding
B. Increasing the time spent near the dose
C. Using appropriate syringe shielding and minimizing handling time
D. Standing closer to the source
Rationale: Shielding and reduced handling time decrease external exposure.
Appropriate tools and shielding should be selected according to the radionuclide
and task.
11. What is the primary purpose of a personnel dosimeter?
A. To measure the patient's administered activity
B. To identify radionuclides
C. To monitor an individual's occupational radiation exposure
D. To calibrate a gamma camera
Rationale: Personnel dosimeters provide a record of occupational radiation
exposure and help identify unusual or excessive exposures that may require
investigation.
12. Where should a whole-body personnel dosimeter generally be worn when a
lead apron is not required?
A. Inside a radiation-shielded cabinet
B. At the location specified by the facility's dosimetry policy, typically on the
torso
C. On the floor
D. Inside the dose calibrator
