Which material is responsible for storing the latent image within the CR IP?

• A. PSP
• B. helium-neon
• C. rare-earth metals
• D. a-Se

Answer: (A)

In computed radiography, the latent image is stored in the photostimulable phosphor layer on the imaging plate. When X-rays expose the plate, energy is trapped in defect sites within the phosphor crystals, creating a latent image that isn’t visible yet. During readout, a laser stimulates those traps, releasing the stored energy as light that is detected and converted into a digital signal. This means the material responsible for storing the latent image is the photostimulable phosphor layer (PSP).

Helium-neon isn’t the storage material; it’s the laser used to read the plate. The term rare-earth metals refers to dopants (like europium) inside the phosphor, but the overall storage medium is the PSP layer itself. Amorphous selenium (a-Se) is used in direct DR detectors, not in CR imaging plates.