Equipment Operation and QA Flashcards

In digital radiography, which exposure indicator value system uses a scale where the target value is approximately 300, with acceptable range of 200-800?

Answer: Kodak EI system

The Kodak/Carestream Exposure Index (EI) system targets approximately 300 (with acceptable range 200-800), where higher numbers indicate higher detector exposure.

A radiographer notices that images from a CR system appear consistently overexposed despite using correct technique. The most likely cause is:

Answer: The exposure indicator shows values consistently higher than the target

Consistently high exposure indicator values confirm that the detector is receiving excess radiation; this indicates a technique or AEC calibration issue causing overexposure.

Which of the following describes the detective quantum efficiency (DQE) of an imaging system?

Answer: A measure of how efficiently a detector converts absorbed x-ray signal into useful image information relative to an ideal detector

DQE expresses how well a detector uses the incident x-ray signal; it combines quantum detection efficiency and noise performance, with a perfect detector having DQE = 1.0.

During fluoroscopy, the image intensifier converts x-ray photons into a visible image through which sequence?

Answer: X-ray → cesium iodide input phosphor light → photocathode electrons → output phosphor

In an image intensifier, x-rays strike the cesium iodide (CsI) input phosphor producing light, which ejects electrons from the photocathode; electrons are accelerated and focused onto the output phosphor.

What is the purpose of the daily sensitometric (sensitometry) QC test in a film-based department?

Answer: To monitor processor performance by evaluating base plus fog, speed, and contrast index on a processed strip

Daily sensitometry tracks film processor consistency by comparing base plus fog, speed index, and contrast index to established control values, detecting processor drift before it affects diagnostic images.

A radiograph exhibits increased optical density on the anode side compared to the cathode side. This finding is most consistent with:

Answer: The patient being positioned with the thick end toward the anode side

The anode side has lower x-ray intensity due to the heel effect; if the thick part of the patient is placed under the anode, the reduced beam intensity is further attenuated, producing lower (not higher) density — thus finding higher density on the anode side indicates the thin end is under the anode, which is the incorrect positioning.

Which of the following is the recommended frequency for performing a flat-panel detector (FDR) uniformity/flat-field calibration?

Answer: As recommended by the manufacturer, typically daily or when detector performance changes are noted

Manufacturers typically recommend flat-field (gain) calibration daily or when detector sensitivity changes, ensuring uniform response across the detector surface and minimizing fixed-pattern noise.