Radiation Safety Flashcards
7 cards from real ARRT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Radiation Safety flashcards as text
Which of the following correctly defines 'effective dose' (E) in radiation protection?
Answer: The weighted sum of equivalent doses to all irradiated tissues, reflecting overall stochastic risk
Effective dose uses tissue weighting factors to sum equivalent doses across organs, yielding a single value (in mSv) that represents whole-body stochastic risk.
For a pediatric CT head scan, compared to an adult protocol, the technologist should generally:
Answer: Reduce mAs significantly because children are more radiosensitive and smaller
Children have greater radiosensitivity and smaller body dimensions, so pediatric CT protocols use substantially lower mAs than adult protocols.
The annual occupational dose limit for the lens of the eye, as updated by NCRP Report No. 172, is:
Answer: 20 mSv
NCRP Report No. 172 (2016) lowered the recommended annual occupational lens dose limit to 20 mSv/year averaged over 5 years, consistent with ICRP 103.
Which of the following patient populations has the HIGHEST radiosensitivity?
Answer: Fetuses and children under 5 years of age
Fetuses and young children are most radiosensitive due to rapidly dividing cells and longer life expectancy over which stochastic effects can manifest.
During a multi-phase CT liver protocol (non-contrast, arterial, portal venous, delayed), which action BEST reduces cumulative patient dose?
Answer: Eliminate phases not essential for the clinical indication and use dose modulation for each phase
Eliminating unnecessary scan phases and applying tube current modulation to each remaining phase are the most effective strategies to reduce cumulative multi-phase CT dose.
What does a noise index (NI) setting in automatic tube current modulation (ATCM) control?
Answer: The target image noise level that drives mA adjustments
The noise index defines the target standard deviation of image noise; ATCM raises or lowers mA to achieve this noise target based on patient attenuation.
Stochastic effects of radiation are characterized by which of the following?
Answer: No dose threshold; probability of occurrence increases with dose
Stochastic effects (e.g., radiation-induced cancer) are assumed to have no threshold; their probability, not severity, increases with dose.