X-ray photoconductors and stabilized a-Se for direct conversion digital flat-panel X-ray image-detectors

Recently developed direct conversion flat-panel X-ray image detectors provi de not only potentially superior images but also enable a simple and conven ient means of achieving digital radiography. The present flat-panel sensors use stabilized a-Se as an X-ray photoconductor to convert absorbed X-ray p hotons to collectable charge carriers. The present paper outlines the basic s of the direct conversion flat-panel X-ray detector, formulates and review s the required X-ray photoconductor properties and examines to what extent stabilized amorphous selenium (a-Se) fulfills these requirements and how it compares with other potential X-ray photoconductors that have been propose d. Charge transport and the electron-hole pair creation energy in stabilize d a-Se are reviewed within the context of our present knowledge. Current ma terials problems and future potential developments are also critically disc ussed.