Which component is responsible for turning X-ray energy into an electrical signal in a digital detector?

• A. Lens assembly
• B. Phosphor screen
• C. Detector elements in pixels
• D. Graticule

Answer: (C)

The signal is generated in the detector elements in the pixel array. In a digital detector, X-ray energy is first converted to light by the scintillator (phosphor screen), but the actual transformation of that light into an electrical signal happens inside each pixel’s photodiode. The photodiode converts the light photons into charge, which is stored and then read out by the integrated electronics (often involving the TFTs). The lens assembly isn’t part of the energy-to-signal conversion, and a graticule is just a measurement grid, not involved in producing the electrical signal.