An improved page-size 127 um pixel amorphous Silicon image sensor for X-Ray diagnostic medical imaging applications

This paper introduces a new high-resolution amorphous Silicon (a-Si) image sensor specifically configured to demonstrate medical X-Ray imaging capabilities. This new imager has an active pixel area of 243.84 mm x 195.072 mm a pixel size of 127 mu m x 127 mu m, and an array size of 1536 data lines by 1920 gate lines, with over 2.95 million pixels. We have introduced a number of improvements both to the a-Si array itself and to the surrounding electronics to obtain a light sensitive area of 57% and a dataline capacitance of approximately 55 pF, which together provide enhanced signal/noise ratio. We have incorporated charge-sensitive amplifiers and 22 bit A/D converters, enabling us to achieve a sufficiently large dynamic range (1000:1) for medical imaging applications. We report on imager performance, including Signal/Noise, Modulation Transfer Function, and summarize other imaging characteristics. We compare these characteristics as a function of different X-Ray phosphors and discuss avenues for future improvement.