ARRT Radiation and Safety 4 — Questions and Answers
Question 1: What is the effective dose limit for a declared pregnant radiation worker during the entire gestation period?
- 1 mSv
- 5 mSv (Correct answer)
- 10 mSv
- 50 mSv
Correct answer: 5 mSv
NCRP recommends limiting fetal dose to no more than 5 mSv (0.5 rem) over the entire gestational period once pregnancy is declared.
Question 2: Which radiation quantity measures the energy deposited per unit mass of tissue?
- Exposure (C/kg)
- Absorbed dose (Gray) (Correct answer)
- Effective dose (Sievert)
- Equivalent dose (Sievert)
Correct answer: Absorbed dose (Gray)
Absorbed dose, measured in Gray (Gy), quantifies energy deposited per kilogram of absorbing material (1 Gy = 1 J/kg).
Question 3: Somatic effects of radiation are those that:
- Occur in future generations of the exposed individual
- Occur in the exposed individual themselves (Correct answer)
- Only affect reproductive organs
- Are always fatal
Correct answer: Occur in the exposed individual themselves
Somatic effects are radiation effects that manifest in the directly exposed individual, as opposed to genetic effects that appear in offspring.
Question 4: The inverse square law states that radiation intensity is:
- Directly proportional to the square of the distance
- Inversely proportional to the square of the distance (Correct answer)
- Inversely proportional to the distance
- Directly proportional to the distance
Correct answer: Inversely proportional to the square of the distance
The inverse square law states that intensity is inversely proportional to the square of the distance, so doubling distance reduces intensity to one-quarter.
Question 5: Which of the following best describes a stochastic radiation effect?
- Has a threshold dose below which it does not occur
- Severity increases with dose
- Probability of occurrence increases with dose, but severity does not (Correct answer)
- Only occurs from acute high-dose exposure
Correct answer: Probability of occurrence increases with dose, but severity does not
Stochastic effects (e.g., radiation-induced cancer) have no threshold; their probability increases with dose, but severity of the effect (e.g., cancer) does not depend on dose.
Question 6: Half-value layer (HVL) is defined as the thickness of material that reduces radiation intensity by:
- 25%
- 50% (Correct answer)
- 75%
- 90%
Correct answer: 50%
HVL is the thickness of absorbing material required to reduce radiation intensity to half (50%) of its original value.
Question 7: A radiologic technologist inadvertently leaves a lead apron unfolded on a hook for months. The PRIMARY concern is:
- Increased weight of the apron over time
- Cracking of the lead lining reducing its protective effectiveness (Correct answer)
- Radiation contamination of the apron surface
- Decreased flexibility of the outer fabric
Correct answer: Cracking of the lead lining reducing its protective effectiveness
Lead aprons must be stored flat or rolled, never folded, because repeated folding causes cracks in the lead lining that reduce radiation attenuation.
ARRT Radiation and Safety 4
What is the effective dose limit for a declared pregnant radiation worker during the entire gestation period?