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.