ARRT Radiation and Safety 5 — Questions and Answers
Question 1: Which of the following ionizing radiation types has the highest relative biological effectiveness (RBE)?
- X-rays
- Gamma rays
- Alpha particles (Correct answer)
- Beta particles
Correct answer: Alpha particles
Alpha particles have a high RBE (up to 20) because their dense ionization along a short track causes severe localized biological damage.
Question 2: What does the radiation weighting factor (W_R) account for in calculating equivalent dose?
- The sensitivity of different tissues to radiation
- The biological effectiveness of different types of radiation (Correct answer)
- The energy of the radiation beam in keV
- The half-life of the radioactive source
Correct answer: The biological effectiveness of different types of radiation
The radiation weighting factor (W_R) reflects the relative biological effectiveness of different radiation types when calculating equivalent dose in Sieverts.
Question 3: Which of the following conditions is classified as a deterministic (non-stochastic) radiation effect?
- Radiation-induced thyroid cancer
- Genetic mutations in offspring
- Radiation-induced cataracts (Correct answer)
- Leukemia from low-level chronic exposure
Correct answer: Radiation-induced cataracts
Radiation-induced cataracts are a deterministic effect with a threshold dose; they occur with certainty above that threshold and severity increases with dose.
Question 4: A technologist must perform a portable chest X-ray at 80 kVp. To maximize distance for protection, they should:
- Hold the detector during exposure
- Use the longest exposure cord or wireless trigger available (Correct answer)
- Stand directly behind the patient
- Reduce mAs to increase distance needed
Correct answer: Use the longest exposure cord or wireless trigger available
Using the longest possible exposure cord or wireless trigger allows the technologist to maximize their distance from the radiation source during the exposure.
Question 5: Primary radiation barriers in a radiographic room must protect against:
- Scatter radiation only
- Leakage radiation only
- The primary (useful) beam (Correct answer)
- Both leakage and scatter radiation only
Correct answer: The primary (useful) beam
Primary barriers are designed to attenuate the primary (useful) X-ray beam and must be located where the unattenuated beam can strike.
Question 6: The NCRP recommends that the maximum permissible dose for members of the general public from artificial sources is:
- 0.1 mSv/year
- 1 mSv/year (Correct answer)
- 5 mSv/year
- 50 mSv/year
Correct answer: 1 mSv/year
NCRP Report No. 116 recommends a continuous effective dose limit of 1 mSv (0.1 rem) per year for members of the general public from controllable sources.
Question 7: Which of the following best describes the concept of 'controlled area' in a radiology department?
- An area where radiation levels are unmonitored
- An area occupied only by patients during procedures
- An area where radiation exposure is controlled and only radiation workers are present during exposures (Correct answer)
- An area restricted to radiologists only
Correct answer: An area where radiation exposure is controlled and only radiation workers are present during exposures
A controlled area is one where radiation exposure is controlled, access is restricted to trained radiation workers, and occupational dose limits apply.
ARRT Radiation and Safety 5
Which of the following ionizing radiation types has the highest relative biological effectiveness (RBE)?