What is a photostimulable phosphor (PSP)?

• A. Stores x-ray energy, releases light
• B. Converts x-rays to light
• C. Detects light
• D. Amplifies x-rays

Answer: (A)

A photostimulable phosphor works by storing energy from x-ray exposure and then releasing light later when stimulated. When x-rays strike the PSP plate, electrons are trapped in the phosphor material, creating a latent image that sits in those traps until readout. During readout, a laser scans the plate and releases the stored energy as light (photostimulated luminescence), which is detected and converted into a digital image. This stored-energy mechanism is what distinguishes PSP from devices that immediately luminize upon exposure or from simple light detectors. So the best description is that it stores x-ray energy and releases light when stimulated.