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Proceedings Paper

Low dose digital X-ray imaging with avalanche amorphous selenium
Author(s): James R. Scheuermann; Amir H. Goldan; Olivier Tousignant; Sébastien Léveillé; Wei Zhao
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Paper Abstract

Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depth-independent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

Paper Details

Date Published: 18 March 2015
PDF: 9 pages
Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94120E (18 March 2015); doi: 10.1117/12.2081247
Show Author Affiliations
James R. Scheuermann, Stony Brook Univ. (United States)
Amir H. Goldan, Stony Brook Univ. (United States)
Olivier Tousignant, Analogic Canada Corp. (Canada)
Sébastien Léveillé, Analogic Canada Corp. (Canada)
Wei Zhao, Stony Brook Univ. (United States)

Published in SPIE Proceedings Vol. 9412:
Medical Imaging 2015: Physics of Medical Imaging
Christoph Hoeschen; Despina Kontos, Editor(s)

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