The effect of finite gain in charge amplifiers in digital radiography

Sreeram Dhurjaty

doi:10.1117/12.596018

20 April 2005 The effect of finite gain in charge amplifiers in digital radiography

Sreeram Dhurjaty

Author Affiliations +

Proceedings Volume 5745, Medical Imaging 2005: Physics of Medical Imaging; (2005) https://doi.org/10.1117/12.596018
Event: Medical Imaging, 2005, San Diego, California, United States

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.

Citation Download Citation

Sreeram Dhurjaty "The effect of finite gain in charge amplifiers in digital radiography", Proc. SPIE 5745, Medical Imaging 2005: Physics of Medical Imaging, (20 April 2005); https://doi.org/10.1117/12.596018

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