Imaging Modalities
Radiography is classified as which type of imaging modality?
Projection Imaging
Which quantity describes radiation exposure at the point where the x-ray beam enters the patient?
Entrance skin exposure, ESE
Which fluoroscopic skin dose level is considered a sentinel event requiring follow-up?
15 Gy
Which situation represents unnecessary patient radiation dose?
A. A justified CT for trauma
B. A repeat exam due to poor positioning
C. Fluoroscopy during cardiac catheterization
D. Portable imaging in the ICU
A repeat exam due to poor positioning
What is the annual effective dose limit for occupational radiation workers?
50 mSv or .05 Sv
Which imaging modality does NOT use ionizing radiation?
MRI and U/S
Why is entrance skin exposure (ESE) commonly used?
It is easy to measure or estimate
Which fluoroscopic feature most directly reduces patient dose by limiting beam-on time?
Pulsed fluoroscopy
What is the primary purpose of the ACR Appropriateness Criteria?
Guide exam justification
What is the annual effective dose limit for the general public?
1 mSv or .001 Sv
Which imaging modalities contribute the largest share of population radiation dose despite fewer exams?
CT and Fluoroscopy
Mean marrow dose (MMD) is most closely associated with what risk?
Leukemia
Dose area product (DAP) is defined as the product of what two factors?
Dose and beam area
Proper collimation reduces patient dose primarily by doing what?
Reducing irradiated tissue volume
What is the total gestational dose limit for a declared pregnant worker?
5 mSv or 0.005 Sv
Which imaging modality is continuous and variable, making dose estimation more difficult?
Fluoroscopy
Genetically significant dose (GSD) estimates radiation risk for which group?
The general population
Why is DAP a better indicator of stochastic risk than skin dose alone?
It accounts for total energy delivered
What is the current recommendation regarding routine gonadal shielding?
It is no longer routinely recommended
What is the recommended monthly dose limit to the embryo/fetus?
0.5 mSv 0.0005 Sv
Which modality often uses automatic brightness control to maintain image quality?
Fluoroscopy
Effective dose accounts for what key factor?
Tissue radiosensitivity
Why does DAP remain constant along the x-ray beam?
Dose and area change inversely
Why are there no regulatory dose limits for patients?
Medical benefit justifies exposure
Exit skin dose (ESD) is lower than entrance skin exposure because most photons are what?
Absorbed within the patient