In a computed radiography (CR) imaging plate, what is released by the phosphor layer when interacting with x-ray photons?

In a computed radiography (CR) imaging plate, when x-ray photons interact with the phosphor layer, they excite the phosphor material, causing it to release light photons. This process occurs because the phosphor layer is made of materials that have the capability to absorb the energy of the x-ray photons and subsequently re-emit that energy in the form of visible light.

The light photons emitted are critical for the formation of the latent image that will later be processed into a digital image when the imaging plate is scanned by a reader. The concept of releasing light as a result of the energy absorbed from x-ray photons is fundamental to how CR systems operate, distinguishing it from other imaging modalities.