In an indirect capture flat-panel detector system, which layer is responsible for converting x-ray energy into light?

• A. Photodiode
• B. Scintillation layer
• C. Analog-to-digital converter
• D. Thin-film transistor array

Answer: (B)

In an indirect capture flat-panel detector, the first step is converting X-ray energy into visible light. This happens in the scintillation layer, where X-rays interacting with the material (such as CsI(Tl) or similar scintillators) produce light photons. That light is then detected by the photodiode layer, which converts the light into an electrical signal that the thin-film transistor (TFT) array can read and route to the analog-to-digital converter for digitization. The scintillation layer is the key element responsible for turning X-ray energy into light, which is why it is the correct choice.