19 March 2010 Photon counting pixel and array in amorphous silicon technology for large area digital medical imaging applications
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Proceedings Volume 7622, Medical Imaging 2010: Physics of Medical Imaging; 76221A (2010); doi: 10.1117/12.844420
Event: SPIE Medical Imaging, 2010, San Diego, California, United States
Abstract
A single photon counting Voltage Controlled Oscillator (VCO) based pixel architecture in amorphous silicon (a-Si) technology is reported for large area digital medical imaging. The VCO converts X-ray generated input charge into an output oscillating frequency signal. Experimental results for an in-house fabricated VCO circuit in a-Si technology are presented and external readout circuits to extract the image information from the VCO's frequency output are discussed. These readout circuits can be optimized to reduce the fixed pattern noise and fringing effects in an imaging array containing many such VCO pixels. Noise estimations, stability simulations and measurements for the fabricated VCO are presented. The reported architecture is particularly promising for large area photon counting applications (e.g. low dose fluoroscopy, dental computed tomography (CT)) due to its very low input referred electronic noise, high sensitivity and ease of fabrication in low cost a-Si technology.
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Mohammad Y. Yazdandoost, Kyung W. Shin, Nader Safavian, Farhad Taghibakhsh, Karim S. Karim, "Photon counting pixel and array in amorphous silicon technology for large area digital medical imaging applications", Proc. SPIE 7622, Medical Imaging 2010: Physics of Medical Imaging, 76221A (19 March 2010); doi: 10.1117/12.844420; https://doi.org/10.1117/12.844420
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KEYWORDS
Amorphous silicon

Sensors

Transistors

Oscillators

Photon counting

Medical imaging applications

X-rays

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