How is stored PSP energy released?

• A. Stimulated by light
• B. Spontaneously
• C. By heat
• D. By pressure

Answer: (A)

Stored energy in photostimulable phosphor (PSP) plates isn’t released on its own. X-ray exposure traps electrons in long-lived states inside the phosphor crystal. To read the image, the plate is stimulated with light—usually a laser. That optical stimulation supplies just enough energy to release the trapped electrons, which then recombine and emit visible light. The emitted light is what’s captured to form the radiographic image. This is different from releasing energy by heat or pressure, or by spontaneous glow without light stimulation.