Dependence of x-ray sensitivity of direct conversion x-ray detectors on x-ray exposure and exposure history

Mohammad Zahangir Kabir; Mohammad Yunus; Safa O. Kasap

doi:10.1117/12.535546

6 May 2004 Dependence of x-ray sensitivity of direct conversion x-ray detectors on x-ray exposure and exposure history

Mohammad Zahangir Kabir, Mohammad Yunus, Safa O. Kasap

Proceedings Volume 5368, Medical Imaging 2004: Physics of Medical Imaging; (2004) https://doi.org/10.1117/12.535546
Event: Medical Imaging 2004, 2004, San Diego, California, United States

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.

Citation Download Citation

Mohammad Zahangir Kabir, Mohammad Yunus, and Safa O. Kasap "Dependence of x-ray sensitivity of direct conversion x-ray detectors on x-ray exposure and exposure history", Proc. SPIE 5368, Medical Imaging 2004: Physics of Medical Imaging, (6 May 2004); https://doi.org/10.1117/12.535546

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