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Proceedings Paper

A comparison of quantum limited dose and noise equivalent dose
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Paper Abstract

Quantum-limited-dose (QLD) and noise-equivalent-dose (NED) are performance metrics often used interchangeably. Although the metrics are related, they are not equivalent unless the treatment of electronic noise is carefully considered. These metrics are increasingly important to properly characterize the low-dose performance of flat panel detectors (FPDs). A system can be said to be quantum-limited when the Signal-to-noise-ratio (SNR) is proportional to the square-root of x-ray exposure. Recent experiments utilizing three methods to determine the quantum-limited dose range yielded inconsistent results. To investigate the deviation in results, generalized analytical equations are developed to model the image processing and analysis of each method. We test the generalized expression for both radiographic and fluoroscopic detectors. The resulting analysis shows that total noise content of the images processed by each method are inherently different based on their readout scheme. Finally, it will be shown that the NED is equivalent to the instrumentation-noise-equivalent-exposure (INEE) and furthermore that the NED is derived from the quantum-noise-only method of determining QLD. Future investigations will measure quantum-limited performance of radiographic panels with a modified readout scheme to allow for noise improvements similar to measurements performed with fluoroscopic detectors.

Paper Details

Date Published: 31 March 2016
PDF: 22 pages
Proc. SPIE 9783, Medical Imaging 2016: Physics of Medical Imaging, 97833T (31 March 2016); doi: 10.1117/12.2216888
Show Author Affiliations
Isaias D. Job, Varian Medical Systems, Inc. (United States)
Sarah J. Boyce, Varian Medical Systems, Inc. (United States)
Michael J. Petrillo, Varian Medical Systems, Inc. (United States)
Kungang Zhou, Varian Medical Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 9783:
Medical Imaging 2016: Physics of Medical Imaging
Despina Kontos; Thomas G. Flohr, Editor(s)

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