ARRT Image Acquisition and Evaluation 2 — Questions and Answers
Question 1: Which exposure indicator value range is typically considered acceptable on most CR and DR systems?
- 50–100
- 300–600 (Correct answer)
- 100–1000
- 1500–3000
Correct answer: 300–600
Most CR/DR systems target an exposure indicator (EI) of approximately 300–600, though exact ranges vary by vendor.
Question 2: A radiograph of the lumbar spine shows the vertebral endplates are not parallel to the beam. Which artifact or error does this represent?
- Grid cutoff
- Beam alignment error (Correct answer)
- Anode heel effect
- Quantum mottle
Correct answer: Beam alignment error
Tilting the tube or patient so endplates are not perpendicular to the central ray causes beam alignment error, projecting structures as distorted.
Question 3: The anode heel effect causes the intensity of the X-ray beam to be greatest near which side of the tube?
- Cathode side (Correct answer)
- Anode side
- Center of the beam
- Both sides equally
Correct answer: Cathode side
X-ray intensity is greatest on the cathode side because the anode's beveled surface absorbs more photons on the anode side.
Question 4: When reviewing a chest radiograph, you notice the left hemidiaphragm appears higher than expected. What is the most likely technical cause if the image is not rotated?
- Patient rotation
- Scoliosis or elevated diaphragm on that side (Correct answer)
- Incorrect collimation
- High kVp technique
Correct answer: Scoliosis or elevated diaphragm on that side
Without rotation, an elevated hemidiaphragm on one side suggests a true anatomical or pathological elevation, not a positioning error.
Question 5: Which factor most directly controls the optical density (brightness) on a digital radiograph?
- kVp
- mAs (Correct answer)
- SID
- Collimation
Correct answer: mAs
mAs controls the number of photons produced and thus the exposure reaching the detector, directly determining image brightness (exposure level).
Question 6: A radiographer uses a 72-inch SID instead of the standard 40-inch SID for a portable AP chest. Which change in technique is required to maintain the same receptor exposure?
- Decrease mAs
- Increase mAs (Correct answer)
- Decrease kVp
- Increase collimation
Correct answer: Increase mAs
Per the inverse square law, doubling SID reduces intensity by a factor of approximately 3.24, requiring mAs to be increased to compensate.
Question 7: Which image quality factor is most degraded by excessive scattered radiation reaching the image receptor?
- Spatial resolution
- Contrast (Correct answer)
- Exposure indicator
- Image sharpness
Correct answer: Contrast
Scatter radiation adds unwanted density throughout the image, reducing subject contrast and making structures harder to differentiate.
ARRT Image Acquisition and Evaluation 2
Which exposure indicator value range is typically considered acceptable on most CR and DR systems?