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Proceedings Paper

The effect of finite gain in charge amplifiers in digital radiography
Author(s): Sreeram Dhurjaty
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Paper Abstract

The effect of finite open-loop gain in charge amplifiers in digital radiography (DR) is analyzed. Practical charge amplifiers are usually integrated into silicon chips and commonly cater to 128 columns. High gains in charge amplifiers have a cost that is associated with greater chip count, greater power dissipation, and sometimes, reduced bandwidth. Even an open-loop gain of 1000 in a charge amplifier can lead to visible artifacts in a DR system, for temperature drifts of a fraction of a degree between calibration of a panel and subsequent usage, while acquiring a radiographic image. Furthermore, small gains in a charge amplifier can rob charge from the pixel capacitor and create residual charge, predominantly in the column capacitances. This can reduce the effective signal-to-noise ratios (SNRs). Analytical models are developed to illustrate the effects of the finite gain in charge amplifiers. Methods are suggested to decrease the deleterious effects of finite gains in charge amplifiers.

Paper Details

Date Published: 20 April 2005
PDF: 6 pages
Proc. SPIE 5745, Medical Imaging 2005: Physics of Medical Imaging, (20 April 2005); doi: 10.1117/12.596018
Show Author Affiliations
Sreeram Dhurjaty, Eastman Kodak Co. (United States)


Published in SPIE Proceedings Vol. 5745:
Medical Imaging 2005: Physics of Medical Imaging
Michael J. Flynn, Editor(s)

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