In digital imaging using a DR detector, image contrast decreases with

• A. excessive kVp values
• B. increased receptor sensitivity
• C. higher exposure
• D. shorter exposure time

Answer: (A)

In digital radiography, image contrast is strongly affected by the energy of the X-ray beam. Using excessive kVp raises the photons’ energy, so they penetrate tissues more uniformly and the differential attenuation between different tissues becomes smaller. This, along with more Compton scatter at higher energies, creates a hazier image with less distinct gray-step differences—so the overall contrast decreases.

The other factors don’t inherently reduce contrast in the same way. Receptor sensitivity changes how strongly the detector responds but doesn’t change the inherent difference in tissue attenuation. Higher exposure improves image signal and reduces noise but doesn’t inherently reduce contrast. Shorter exposure time primarily affects motion blur, not the inherent subject contrast.