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6 October 1999 Achieving high-resolution in flat-panel imagers for digital radiography
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Amorphous silicon (a-Si:H) matrix-addressed imager sensors are the leading new technology for digital medical x-ray imaging. Large-area systems are now commercially available with good resolution and large dynamic range. These systems image x-rays either by detecting light emission from a phosphor screen onto an a-Si:H photodiode, or by collecting ionization charge in a thick x-ray absorbing photoconductor with as selenium, and both approaches have been widely discussed in the literature. While these systems meet the performance needs for general radiographic imaging, further improvements in sensitivity, noise and resolution are needed to fully satisfy the requirements for fluoroscopy and mammography. The approach taken for this paper uses indirect detection, with a phosphor layer for x-ray conversion. The thin a-Si:H photodiode layer for detects the scintillation light. In contrast with the present generation of devices, which have a mesa-isolated sensor at each pixel, these imagers use a continuous sensor covering the entire front surface of the array. The p+ and i layers of a-Si:H are continuous, while the n+ contact has been patterned to isolate adjacent pixels. The continuous photodiode layer maximizes light absorption from the phosphor and provides high x-ray conversion efficiency.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jeffrey T. Rahn, Francesco Lemmi, Jeng-Ping Lu, Ping Mei, Robert A. Street, Steve E. Ready, Jackson Ho, Raj B. Apte, Koenraad Van Schuylenbergh, Rachel Lau, Richard L. Weisfield, Rene Lujan, and James B. Boyce "Achieving high-resolution in flat-panel imagers for digital radiography", Proc. SPIE 3770, Medical Applications of Penetrating Radiation, (6 October 1999);

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