Improved page-size 127-um-pixel amorphous-silicon image sensor for x-ray diagnostic medical imaging applications

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Abstract
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 micrometers X 127 micrometers , 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 percent and a dataline capacitance of approximately 55 pF, which together provide enhanced signal/noise ratio. We have incorporated charge-sensitive amplifiers and 12 bit A/D converters, enabling us to achieve a sufficiently large dynamic range 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.

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