What is PSP made of?

• A. Europium-doped barium fluorohalide
• B. Europium-doped calcium fluoride
• C. Europium-doped barium chloride
• D. Europium-doped strontium bromide

Answer: (A)

Photostimulable phosphor plates use a storage lattice where X-ray exposure creates trapped charges that are held until read out. The material that makes this possible is a europium-doped barium fluorohalide, typically BaFBr:Eu2+. The europium dopant provides the luminescent centers that trap energy and later release it when stimulated by a red laser during scanning. The fluorohalide host lattice gives the right trap depths and efficient light emission, yielding high sensitivity, stability, and good image resolution. Other europium-doped materials (like calcium fluoride, barium chloride, or strontium bromide) don’t offer the same combination of trapping efficiency and readout characteristics, so they aren’t the standard PSP material.