Image Acquisition and Evaluation 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 Image Acquisition and Evaluation flashcards as text
Which exposure indicator value range is typically considered acceptable on most CR and DR systems?
Answer: 300–600
Most CR/DR systems target an exposure indicator (EI) of approximately 300–600, though exact ranges vary by vendor.
A radiograph of the lumbar spine shows the vertebral endplates are not parallel to the beam. Which artifact or error does this represent?
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.
The anode heel effect causes the intensity of the X-ray beam to be greatest near which side of the tube?
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.
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?
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.
Which factor most directly controls the optical density (brightness) on a digital radiograph?
Answer: mAs
mAs controls the number of photons produced and thus the exposure reaching the detector, directly determining image brightness (exposure level).
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?
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.
Which image quality factor is most degraded by excessive scattered radiation reaching the image receptor?
Answer: Contrast
Scatter radiation adds unwanted density throughout the image, reducing subject contrast and making structures harder to differentiate.