The use of point defects in digital radiography

Abstract

Colour centres in alkali halides such as F centres and H or VK centres have been studied intensely for decades but have hardly found any applications. However, in activator-doped halides their generation mechanisms upon irradiation with X-rays, their room temperature stability and photostimulated recombination processes are the basis of important applications in digital radiography, which has recently become commercially available. An overview is given of the present understanding of the point defect mechanisms in the commercially used X-ray storage phosphor BaFBr:Eu2+ and its shortcomings. Further developments in BaFBr-based X-ray storage phosphors are discussed. Promising cubic X-ray storage phosphor materials with high figures of merit and potentially higher spatial resolution, such as RbBr:Ga+, CsBr:Ga+, RbBr:Eu2+ and CsBr:Eu2+ have recently been studied in detail and an overview of the generation and recombination mechanisms of the electron and hole trap centres active in the information storage and read-out processes is presented. Finally, first results are shown of the use of glass ceramics as potential new storage material in particular for high-energy X-rays.