Which receptor type uses europium-activated barium fluorohalide in its crystalline emulsion to store latent images?

• A. Phosphor plate
• B. Film receptor
• C. Digital sensor
• D. Intensifying screen

Answer: (A)

Storage phosphor plates use europium-activated barium fluorohalide crystals to hold the image after exposure. When X-rays hit the plate, electrons are trapped in metastable states within the BaFBr:Eu2+ (and related BaFCl:Eu2+) crystals, creating a latent image that remains stored until read. To read it, a laser in the scanner stimulates the trapped electrons to release their energy as light (photostimulated luminescence), and this emitted light is captured and converted into a digital image. This stored latent-image capability is the hallmark of storage phosphor plate technology. In contrast, traditional film uses silver halide grains that require chemical processing to reveal an image, digital sensors rely on solid-state electronics without a latent storage step, and intensifying screens in film-screen systems use phosphors to convert X-rays to light but do not store a latent image in a crystalline emulsion.