Performance of a real time selenium based x-ray detector for fluoroscopy

As amorphous selenium based flat panel detectors gain more interest for direct, real-time x-ray imaging, we report in this paper the performance of such a detector by ANRAD Corporation. This new detector is based on a 1536 x 1536 array of amorphous silicon TFT pixels coupled with a 1000 mum selenium converter biased at 10 V/mum. Each 150 mum x 150 mum pixel is made of a thin film transistor (TFT), a storage capacitor and a collecting electrode having a geometrical fill factor of 77% and an effective fill factor of nearby 100%. New TFT architecture and high speed electronics allow operation of this new detector under a large range of conditions from low dose fluoroscopy (few muR/frame) to DR and it supports frame rates from single shot to 60 fps. Image lag following x-ray excitation was measured to be very low. Key imaging parameters for this real time x-ray detection system such as: detective quantum efficiency (DQE), signal to noise ratio (SNR) and modulation transfer function (MTF) were measured. These results together with frames extracted from a low dose fluoroscopy sequence and an anthropomorphic phantom image will be presented. The measurements show that the dynamic performance of this new detector is very well suited for real time imaging in fluoroscopic and/or cardiac applications.