Radiography Exam Image Production & Processing 1 — Questions and Answers
Question 1: In digital radiography, what does the exposure index (EI) primarily indicate?
- The amount of radiation the patient received
- The amount of radiation that reached the detector (Correct answer)
- The contrast resolution of the image
- The spatial resolution of the detector
Correct answer: The amount of radiation that reached the detector
The exposure index is a measure of the radiation exposure reaching the digital detector, used to assess whether the detector was properly exposed.
Question 2: Which artifact in computed radiography (CR) appears as a ghost image from a previous exposure due to incomplete erasure?
- Grid artifact
- Quantum mottle
- Lag artifact (ghosting) (Correct answer)
- Moiré pattern
Correct answer: Lag artifact (ghosting)
Lag (ghosting) occurs when residual signal from a previous exposure is not fully erased from the PSP plate before the next exposure.
Question 3: What is the primary advantage of direct digital radiography (DR) over computed radiography (CR)?
- Lower cost of equipment
- Immediate image availability without plate handling (Correct answer)
- Better spatial resolution
- Smaller file sizes
Correct answer: Immediate image availability without plate handling
DR panels provide immediate image display because there is no separate plate processing step, improving workflow efficiency.
Question 4: In digital imaging, which term describes the range of exposure values over which the detector can produce a diagnostic image?
- Spatial resolution
- Dynamic range (Correct answer)
- Quantum efficiency
- Modulation transfer function
Correct answer: Dynamic range
Dynamic range refers to the range of exposure values (from very low to very high) that a digital detector can accurately capture and display.
Question 5: What happens to image noise (quantum mottle) when mAs is decreased in digital radiography?
- Noise decreases
- Noise increases because fewer photons form the image (Correct answer)
- Noise is unaffected because digital processing corrects it
- Noise only changes with kVp
Correct answer: Noise increases because fewer photons form the image
Reducing mAs decreases the number of photons reaching the detector, resulting in a noisier (more mottled) image due to quantum noise.
Question 6: Which factor primarily determines the spatial resolution of a digital detector system?
- kVp setting
- mAs setting
- Pixel size (detector element size) (Correct answer)
- SID
Correct answer: Pixel size (detector element size)
Spatial resolution in digital radiography is primarily limited by the size of the detector elements (pixels) — smaller pixels yield higher resolution.
Radiography Exam Image Production & Processing 1
In digital radiography, what does the exposure index (EI) primarily indicate?