Radiation Protection Principles 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 Protection Principles flashcards as text
Which cell type is considered the most radiosensitive in the human body?
Answer: Lymphocytes
Lymphocytes are highly radiosensitive and show decreases in count at relatively low doses, making them a useful biological indicator of exposure.
The occupational lens of eye dose limit per year is set at what value by NCRP?
Answer: 150 mSv
NCRP sets the annual occupational equivalent dose limit for the lens of the eye at 150 mSv (15 rem).
Which factor describes the relative biological effectiveness of different radiation types and is used to calculate equivalent dose?
Answer: Quality factor (Q) or radiation weighting factor (wR)
The radiation weighting factor (wR), formerly called quality factor, converts absorbed dose to equivalent dose by accounting for radiation type's biological effectiveness.
Adding filtration to an X-ray beam primarily reduces patient dose by:
Answer: Removing low-energy photons that would be absorbed in superficial tissues
Added filtration (typically aluminum) absorbs low-energy photons that would deposit dose in superficial tissue without contributing to the image.
What is the minimum total filtration required for X-ray tubes operating above 70 kVp, per federal regulation?
Answer: 2.5 mm Al equivalent
Federal regulations (21 CFR 1020.30) require a minimum total filtration of 2.5 mm aluminum equivalent for tubes operating above 70 kVp.
Which radiation protection action most directly reduces scatter to the patient during a radiographic exam?
Answer: Collimating the field to the area of interest
Collimation reduces the volume of irradiated tissue, which directly decreases the amount of scatter produced within the patient.
Which organization establishes radiation protection recommendations that form the basis of US regulatory dose limits?
Answer: NCRP (National Council on Radiation Protection and Measurements)
The NCRP issues scientific recommendations on radiation protection that are adopted by federal and state regulatory agencies in the US.