Which of the following is NOT a factor that affects spatial resolution in digital radiography (DR)?

• A. milliampere-seconds (mAs)
• B. Detector element (DEL) size
• C. Detector element (DEL) pitch
• D. Fill factor

Answer: (A)

Spatial resolution in digital radiography comes from how finely the image is sampled by the detector and how much active area of each detector element is collecting signal. The detector element size sets the basic pixel size, so smaller elements allow higher spatial frequency and better ability to distinguish close objects. The pitch, the center-to-center spacing between detector elements, also limits sampling density; a smaller pitch means denser sampling and improved resolution. Fill factor is the portion of each detector element that is sensitive to signal; a higher fill factor increases signal capture and reduces geometric blur, contributing to better resolution. In contrast, milliampere-seconds (mAs) affects the number of photons and image noise, not the sampling geometry or blur characteristics, so it does not change spatial resolution.