Physics and Current Understanding of X-Ray Storage Phosphors

BaFBr doped with Eu2+ is the most successful X-ray storage phosphor used for digital radiography so far. The mechanisms of information storage and subsequent read-out are, however, not yet fully understood. The present understanding of the structures and reactions of the radiation-induced point defects involved in these processes are critically discussed. The shortcomings of X-ray storage phosphor screens based on BaFBr:Eu2+ are the inferior spatial resolution compared to conventional X-ray films. Also reviewed are therefore alternative storage phosphors such as alkali halides doped with Eu2+, Ga+, In+, or Tl+ or elpasolites doped with Ce3+ or Eu2+ which are also promising with high figures of merit and potentially higher spatial resolution. A completely new approach is the use of suitably doped glasses and glass ceramics. First results on fluorozirconate glass ceramics with good storage and read-out properties are reviewed.