GXMO GXMO Quality Control and Maintenance 2 — Questions and Answers
Question 1: Automatic exposure control (AEC) devices should be tested regularly. A common QC test for AEC verifies:
- Consistency of mAs output across different kVp settings (Correct answer)
- Accuracy of the timer circuit only
- Collimator light-to-field correspondence
- Focal spot alignment
Correct answer: Consistency of mAs output across different kVp settings
AEC QC tests confirm that the system delivers consistent mAs (and therefore consistent receptor exposure) across a range of kVp values and patient thicknesses.
Question 2: Artifacts caused by dirt or debris on a CR (computed radiography) imaging plate most commonly appear as:
- White (unexposed) or black dots and lines on the image (Correct answer)
- Increased overall image noise
- Reduced spatial resolution only
- Overexposure in one corner
Correct answer: White (unexposed) or black dots and lines on the image
Foreign material on a CR plate blocks or scatters the laser during readout, creating white (or occasionally dark) artifacts on the processed image.
Question 3: The base-plus-fog (B+F) level of radiographic film processed without exposure should be:
- 0.18 or less (Correct answer)
- 0.50 or less
- 1.0 or less
- Between 0.5 and 1.0
Correct answer: 0.18 or less
A B+F density of 0.18 or less indicates that the film base and chemical fog are within acceptable limits, ensuring adequate image contrast.
Question 4: Which component of a digital radiography system converts X-ray photons directly into an electrical signal without an intermediate step?
- Direct DR flat panel detector (amorphous selenium) (Correct answer)
- Indirect DR flat panel detector (amorphous silicon + scintillator)
- Computed radiography (CR) imaging plate
- Film-screen cassette
Correct answer: Direct DR flat panel detector (amorphous selenium)
Direct DR detectors use amorphous selenium to convert X-rays directly to electrical charge, while indirect detectors use a scintillator to first convert X-rays to light.
Question 5: Repeat analysis in a quality control program is performed to:
- Identify common causes of repeat exposures and reduce patient dose (Correct answer)
- Measure X-ray tube output
- Calibrate the processor developer temperature
- Verify collimator accuracy
Correct answer: Identify common causes of repeat exposures and reduce patient dose
Repeat analysis tracks the frequency and reasons for repeated exposures, allowing targeted corrective action to reduce unnecessary patient radiation dose.
Question 6: The speed of an X-ray film-screen system refers to:
- Its sensitivity to radiation (ability to produce diagnostic density with less exposure) (Correct answer)
- The rate at which the processor develops film
- The time required for automatic exposure control to terminate the exposure
- Focal spot size
Correct answer: Its sensitivity to radiation (ability to produce diagnostic density with less exposure)
Screen-film speed (e.g., 100, 200, 400) indicates the system's sensitivity; higher speed requires less radiation to achieve the same image density, reducing patient dose.
GXMO GXMO Quality Control and Maintenance 2
Automatic exposure control (AEC) devices should be tested regularly.
A common QC test for AEC verifies: