Infographics / Digital Radiography

Photostimulable Phosphor (CR) Trapping & Readout Mechanism

Cross-section in three stages: X-ray exposure traps electrons as a latent image in a BaFBr:Eu phosphor; a red or infrared laser scans and releases the trapped electrons, which emit shorter-wavelength blue light detected by a photomultiplier tube and digitised; the plate is then erased by flooding with bright light for reuse.

Computed radiography photostimulable-phosphor imaging-plate mechanism Cross-section in three stages: X-ray exposure traps electrons as a latent image in a BaFBr:Eu phosphor; a red or infrared laser scans and releases the trapped electrons, which emit shorter-wavelength blue light detected by a photomultiplier tube and digitised; the plate is then erased by flooding with bright light for reuse. 1 — X-ray exposure: writing the latent image X-ray photons BaFBr:Eu²⁺ layer latent image X-rays raise electrons into metastable F-centre (halide-vacancy) traps — this stored charge is the latent image. 2–4 — Laser readout: releasing and detecting the signal photomultiplier tube red / IR laser blue light (shorter λ) 2 — A red / IR laser scans the plate, giving trapped electrons enough energy to escape the F-centre traps. 3 — Freed electrons return to the ground state, emitting shorter-wavelength blue light. 4 — This weak blue signal is collected and detected by a photomultiplier tube, then digitised. 5 — Erasure: readying the plate for reuse bright light flood traps emptied 5 — Flooding the plate with bright light empties residual traps (not a laser), so the plate can be reused.
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