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Proceedings Paper

Substrate effect on indirect digital radiography system performance
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Paper Abstract

In a typical indirect flat-panel digital radiography detector, a phosphor screen is coupled to an a-Si:H imaging array, whose pixels comprise an a-Si:H photodiode and an a-Si:H TFT switch. This two-dimensional array is fabricated on a thin glass substrate that usually contains a rather high concentration of heavy elements such as barium. In previous system performance analyses, only the effect of K-fluorescence reabsorption in the phosphor screen was included. The effect of K-fluorescence from heavy elements in the glass substrate of the array was not taken into account. This K-fluorescence may be excited directly by primary x-rays that penetrate the overlying phosphor and interact in the glass, or by K-fluorescence x-rays that escape from the phosphor into the glass. In this paper, we extend the parallel-cascaded linear systems model to include the effect of K-fluorescence from heavy elements in the glass substrate. As an example, the MTF, NPS, and DQE of an indirect flat-panel imager consisting of a Gd2O2S:Tb phosphor screen and an a-Si:H photodiode/TFT array fabricated on a glass substrate containing barium, are calculated. Degradations in MTF and DQE as a result of the K-fluorescence from the substrate are presented and discussed.

Paper Details

Date Published: 2 March 2006
PDF: 13 pages
Proc. SPIE 6142, Medical Imaging 2006: Physics of Medical Imaging, 61423J (2 March 2006); doi: 10.1117/12.655564
Show Author Affiliations
A. R. Lubinsky, SUNY/Stony Brook (United States)
Kwok L. Yip, Eastman Kodak Co. (United States)
David P. Trauernicht, Eastman Kodak Co. (United States)
John Yorkston, Eastman Kodak Co. (United States)

Published in SPIE Proceedings Vol. 6142:
Medical Imaging 2006: Physics of Medical Imaging
Michael J. Flynn; Jiang Hsieh, Editor(s)

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