Spatial resolution of a glass-ceramic X-ray storage phosphor

The spatial resolution of a glass-ceramic X-ray storage phosphor imaging plate has been measured using a scanned and focussed laser beam. The glass ceramic comprises orthorhombic phase barium chloride crystals containing europium ions embedded in a fluorozirconate glass matrix. The modulation transfer function extends to significantly higher frequencies than for a commercial imaging plate based on powdered BaFBr:Eu crystals; the modulation transfer function falls to a value of 0.3 at 10 lp/mm compared to 2 lp/mm for the commercial plate. The modulation transfer function has a bimodal character which we ascribe to component responses from the focussed laser beam volume and from the surrounding scattering halo. A limitation on performance of this particular glass ceramic is the occurrence of bubbles and other defects which scatter the read-out light beam and reduce the uniformity of the response.