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Proceedings Paper

Dependence of x-ray sensitivity of direct conversion x-ray detectors on x-ray exposure and exposure history
Author(s): Mohammad Zahangir Kabir; Mohammad Yunus; Safa O. Kasap
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Paper Abstract

The dependence of the x-ray sensitivity of a-Se based x-ray image detectors on repeated x-ray exposures and exposure history is studied by considering deep trapping of charge carriers, trapped charges due to previous exposures, bimolecular recombination, space charge effects and electric field dependent electron-hole pair creation energy. We numerically solve the continuity equations of both holes and electrons, trapping rate equations, and the Poison equation across the photoconductor for long pulse x-ray exposures. The electric field distribution across the photoconductor and the relative x-ray sensitivity as a function of cumulated x-ray exposure have been studied for both mammographic and chest radiographic applications. The electric field distribution across the photoconductor has been found to vary widely for high exposures. The relative x-ray sensitivity decreases with increasing cumulated x-ray exposure and tents to saturate. The sensitivity reduction at negative bias is more pronounced than at positive bias.

Paper Details

Date Published: 6 May 2004
PDF: 7 pages
Proc. SPIE 5368, Medical Imaging 2004: Physics of Medical Imaging, (6 May 2004); doi: 10.1117/12.535546
Show Author Affiliations
Mohammad Zahangir Kabir, Univ. of Saskatchewan (Canada)
Mohammad Yunus, Univ. of Saskatchewan (Canada)
Safa O. Kasap, Univ. of Saskatchewan (Canada)

Published in SPIE Proceedings Vol. 5368:
Medical Imaging 2004: Physics of Medical Imaging
Martin J. Yaffe; Michael J. Flynn, Editor(s)

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