High-performance amorphous silicon image sensor for x-ray diagnostic medical imaging applications

摘要

Abstract: Following our previous report concerning thedevelopment of a 127 micrometer resolution, 7.4 millionpixel, 30 $MUL 40 cm$+2$/ active area, flat panelamorphous Silicon (a-Si) x-ray image sensor, this paperdescribes enhancements in image sensor performance inthe areas of image lag, linearity, sensitivity, andelectronic noise. New process improvements infabricating a-Si thin film transistor (TFT)/photodiodearrays have reduced first-frame image lag to less than2%, and uniformity in photoresponse to less than 5%over the entire 30 $MUL 40 cm$+2$/ active area.Detailed analysis of image lag vs. time and x-ray dosewill be discussed. An improved charge amplifier hasbeen introduced to suppress image cross-talk artifactscaused by charge amplifier saturation, and systemlinearity has been optimized to eliminate bandingeffects among charge amplifiers. Preliminarysensitivity improvements through the deposition ofCsI(Tl) directly on the arrays are reported, as well asoverall imaging characteristics of this improved imagesensor. !10