Low dose digital X-ray imaging with avalanche amorphous selenium

James R. Scheuermann; Amir H. Goldan; Olivier Tousignant; Sébastien Léveillé; Wei Zhao

doi:10.1117/12.2081247

18 March 2015 Low dose digital X-ray imaging with avalanche amorphous selenium

James R. Scheuermann, Amir H. Goldan, Olivier Tousignant, Sébastien Léveillé, Wei Zhao

Proceedings Volume 9412, Medical Imaging 2015: Physics of Medical Imaging; 94120E (2015) https://doi.org/10.1117/12.2081247
Event: SPIE Medical Imaging, 2015, Orlando, Florida, United States

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.

Citation Download Citation

James R. Scheuermann, Amir H. Goldan, Olivier Tousignant, Sébastien Léveillé, and Wei Zhao "Low dose digital X-ray imaging with avalanche amorphous selenium", Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94120E (18 March 2015); https://doi.org/10.1117/12.2081247

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