An x-ray photon is absorbed with the phosphor layer of a CR plate through what type of interaction?

• A. Characteristic interaction
• B. Photoelectric interaction
• C. Compton interaction
• D. Classical interaction

Answer: (B)

Absorption in the CR phosphor layer mainly happens through the photoelectric interaction. In these high‑Z storage phosphor materials, an incident x-ray photon transfers its energy to a tightly bound electron, ejecting it and creating a trapped charge that stores energy. This stored energy is what becomes the latent image and is later released as light when the plate is stimulated by a laser during reading. Compton scattering would simply deflect the photon and deposit less energy locally, making it less effective for creating the stored signal, while other terms aren’t the primary mechanism for energy deposition in this context.