Sci‐Fri AM: YIS‐10: Development of a flat panel detector with avalanche gain for low‐dose x‐ray imaging

Digital flat panel detectors are increasingly being used in radiography and fluoroscopy. The imaging performance of current systems, however, is compromised by electronic noise at the low X-ray exposures employed in fluoroscopy and low-dose radiography. In other words, current flat panel detectors are not quantum noise limited at these low radiation exposures. There is thus a need to develop an imaging detector with the high sensitivity of an X-ray image intensifier and the inherent advantages of a solid-state flat panel detector. Towards this end, we have developed and characterized a novel solid-state device capable of providing very high avalanche gains and an excellent temporal response. The device which is based on the amorphous photoconductor a-Se, is scalable (i.e. can be manufactured in large areas), can overcome electronic noise even at the lowest X-ray exposures used in diagnostic imaging (0.1 μR/frame at the detector) and has a very low level of dark current. Here, we investigate the gain and temporal characteristics of this device and discuss its applicability for low exposure X-ray imaging as well as the effects of avalanche gain on the detective quantum efficiency. Coupled to a high-resolution structured CsI X-ray scintillator and a thin film transistor array, this device should provide a true solid-state alternative to the X-ray image intensifier, which is both robust and cost-effective. This should open the door to dose-efficient flat panel imagers for radiography and fluoroscopy as well as a number of other demanding medical imaging applications.