Which interaction is responsible for the absorption of x-ray photons in the phosphor layer of CR imaging?

Which interaction is responsible for the absorption of x-ray photons in the phosphor layer of CR imaging?

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

Answer: (A)

The main concept here is that the absorption of diagnostic x-ray photons in the phosphor layer occurs primarily through the photoelectric effect. In a high‑Z storage phosphor like BaFBr:Eu2+, an incoming x-ray photon is most likely to be completely absorbed by an inner-shell electron, ejecting that electron and creating a trapped charge in the phosphor lattice. This energy deposition is what stores the latent image, later read out when stimulated by a laser. Compton scattering, while possible, involves only partial energy transfer to a recoil electron and does not produce the same stored energy signal. Characteristic radiation is the photons emitted as electrons fill the vacancy after a photoelectric event; it is a consequence of absorption rather than the absorption mechanism itself. Classical (low‑energy) interactions aren’t the dominant process at diagnostic energies in this material.

The main concept here is that the absorption of diagnostic x-ray photons in the phosphor layer occurs primarily through the photoelectric effect. In a high‑Z storage phosphor like BaFBr:Eu2+, an incoming x-ray photon is most likely to be completely absorbed by an inner-shell electron, ejecting that electron and creating a trapped charge in the phosphor lattice. This energy deposition is what stores the latent image, later read out when stimulated by a laser. Compton scattering, while possible, involves only partial energy transfer to a recoil electron and does not produce the same stored energy signal. Characteristic radiation is the photons emitted as electrons fill the vacancy after a photoelectric event; it is a consequence of absorption rather than the absorption mechanism itself. Classical (low‑energy) interactions aren’t the dominant process at diagnostic energies in this material.