Two-dimensional photon counter for x-ray imaging

Abstract

This paper characterizes an imaging x-ray detector formed by coupling a gadolinium oxysulphide phosphor to the input of an optical imaging photon detector. The device is small, light, easy to use, and features a direct digital readout. It exhibits fairly high efficiency (40%–80%) and high resolution (160 μm-width point spread function) near the center of its 40-mm active area. There is a small amount of pincushion distortion which seems to be associated with a loss in resolution toward the edge of the active area. The device has very low noise and can be used at x-ray fluxes down to about 0.1 x-ray/mm2/s without loss of accuracy but it is count rate limited at 105 x rays/s over the active area and so is not usable in high-flux situations such as are often found at synchrotrons. We have used the device to record good diffraction patterns from striated rabbit muscle in 30 min on a rotating anode x-ray generator: less than one tenth the time needed under similar conditions when using film.