CT Radiation Safety and Dosimetry Flashcards
6 cards from real Computed Tomography Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CT Radiation Safety and Dosimetry flashcards as text
Which unit is used to express the effective radiation dose received by a patient during a CT scan?
Answer: Millisievert (mSv)
Millisievert (mSv) is the SI unit used to express effective dose, which accounts for the biological effect of radiation on different tissues.
What does the term CTDI stand for in CT radiation dosimetry?
Answer: Computed Tomography Dose Index
CTDI (Computed Tomography Dose Index) is a standardized measure of radiation dose output from a CT scanner for a single rotation.
Which principle of radiation protection states that doses should be kept as low as reasonably achievable?
Answer: ALARA
ALARA (As Low As Reasonably Achievable) is the guiding principle for minimizing radiation exposure to patients and staff.
Increasing the mAs in CT by a factor of 4 will have what effect on image noise?
Answer: Reduce noise by 50%
Since noise is proportional to 1/√mAs, quadrupling mAs reduces noise by half (√4 = 2).
What is the primary purpose of using automatic exposure control (AEC) in CT?
Answer: Adapt tube current to patient size and anatomy
AEC (also called tube current modulation) automatically adjusts mA based on patient attenuation to optimize image quality while minimizing dose.
Which CT parameter, when increased, directly increases patient radiation dose?
Answer: mAs
Increasing mAs increases the number of X-ray photons produced, directly increasing the radiation dose delivered to the patient.