The acronym PSP in CR stands for:

• A. Primary scintillation phosphor
• B. Positron-sensitive phosphor
• C. Photon-scatter phosphor
• D. Photo-stimulable phosphor

Answer: (D)

In computed radiography, the line up is about a material that stores part of the X-ray energy as trapped electrons in a phosphor layer. When you later read the plate, a laser stimulates those traps and the stored energy is released as light in a process called photostimulated luminescence. This lets the plate hold the image until it’s read, rather than emitting light immediately like a conventional scintillator. The term for this material is photostimulable phosphor, which is why the answer is that option. The other descriptions describe different concepts that don’t match how CR readout works.