Radiography Exam ARRT Radiography 5 — Questions and Answers
Question 1: The specific absorption of x-ray photons by the photoelectric effect is MOST likely to occur when:
- Photon energy greatly exceeds the binding energy of the electron
- Photon energy is slightly greater than the binding energy of the electron (Correct answer)
- The patient has low atomic number (Z) tissues
- High kVp techniques are used
Correct answer: Photon energy is slightly greater than the binding energy of the electron
Photoelectric absorption is most probable when the incident photon energy just exceeds the binding energy of the inner-shell electron.
Question 2: Which modality uses gradient magnetic fields superimposed on the static magnetic field to spatially encode the MR signal?
- CT gantry rotation
- Radiofrequency (RF) coils
- Gradient coils (Correct answer)
- Shim coils
Correct answer: Gradient coils
Gradient coils create small, controlled variations in the magnetic field used for slice selection, frequency encoding, and phase encoding in MRI.
Question 3: The Bucky factor (grid factor) represents:
- The ratio of primary to scatter radiation transmitted
- How much more mAs is required when using a grid compared to non-grid technique (Correct answer)
- The number of grid lines per centimeter
- The ratio of grid height to strip thickness
Correct answer: How much more mAs is required when using a grid compared to non-grid technique
The Bucky factor indicates the exposure increase needed when adding a grid; a factor of 4 means 4× more mAs is required.
Question 4: For the AP axial projection of the coccyx, the central ray is angled:
- 10° cephalad
- 10° caudad
- 30° cephalad
- 30° caudad (Correct answer)
Correct answer: 30° caudad
A 10–30° caudad angle is directed to 2 inches superior to the pubic symphysis to project the coccyx free of superimposition.
Question 5: Which of the following is a late (deterministic) effect of high-dose radiation exposure?
- Increased cancer risk
- Cataracts of the lens (Correct answer)
- Genetic mutations in offspring
- Leukemia from low-level exposure
Correct answer: Cataracts of the lens
Cataracts are a deterministic (non-stochastic) effect with a threshold dose; they occur at high exposures to the ocular lens.
Question 6: The Society of Motion Picture and Television Engineers (SMPTE) test pattern is used in radiology to evaluate:
- Computed tomography HU accuracy
- Display monitor performance and quality (Correct answer)
- Fluoroscopy dose output rates
- Digital detector uniformity
Correct answer: Display monitor performance and quality
The SMPTE test pattern is a standardized chart used to assess display monitor luminance, contrast, resolution, and artifact performance.
Question 7: A patient has a history of iodine contrast allergy. The most appropriate pre-medication regimen typically includes:
- Aspirin and diphenhydramine 1 hour before
- Prednisone 50 mg at 13 hours, 7 hours, and 1 hour before contrast, plus diphenhydramine (Correct answer)
- IV epinephrine immediately before injection
- Furosemide and saline hydration only
Correct answer: Prednisone 50 mg at 13 hours, 7 hours, and 1 hour before contrast, plus diphenhydramine
The standard corticosteroid premedication protocol uses prednisone (50 mg PO) at 13, 7, and 1 hour before contrast, often with diphenhydramine 1 hour before.
Radiography Exam ARRT Radiography 5
The specific absorption of x-ray photons by the photoelectric effect is MOST likely to occur when: