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Proceedings Paper

Measuring the presampled MTF from a reduced number of flat-field images using the noise response (NR) method
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Paper Abstract

We evaluate a new method for measuring the presampled modulation transfer function (MTF) using the noise power spectrum (NPS) obtained from a few flat-field images acquired at one exposure level. The NPS is the sum of structure, quantum, and additive instrumentation noise, which are proportional to exposure squared, exposure, and a constant, respectively, with the spatial-frequency dependence of the quantum noise depending partly on the detector MTF. Cascaded linear-systems theory was used to derive an exact and generic relationship that was used to isolate noise terms and enable determination of the MTF directly from the noise response, thereby circumventing the need for precision test objects (slit, edge, etc.) as required by standard techniques. Isolation of the quantum NPS by fitting the total NPS versus exposure obtained using 30 flat-field images each at six or more different exposure levels with a linear regression provides highly accurate MTFs. A subset of these images from indirect digital detectors was used to investigate the accuracy of measuring the MTF from 30 or fewer flat-field images obtained at a single exposure level. Analyzing as few as two images acquired at a single exposure resulted in no observable systematic error. Increasing the number of images analyzed resulted in an increase in accuracy. Fifteen images provided comparable accuracy with the most rigorous slope approach, with less than 5% variability, suggesting additional image acquisitions may be unnecessary. Reducing the number of images acquired for the noise response method further simplifies and facilitates routine MTF measurements.

Paper Details

Date Published: 16 March 2011
PDF: 6 pages
Proc. SPIE 7961, Medical Imaging 2011: Physics of Medical Imaging, 79614G (16 March 2011); doi: 10.1117/12.877890
Show Author Affiliations
Andrew Kuhls-Gilcrist, Toshiba America Medical Systems, Inc. (United States)
Amit Jain, Toshiba Stroke Research Ctr., Univ. at Buffalo (United States)
Daniel R. Bednarek, Toshiba Stroke Research Ctr., Univ. at Buffalo (United States)
Stephen Rudin, Toshiba Stroke Research Ctr., Univ. at Buffalo (United States)


Published in SPIE Proceedings Vol. 7961:
Medical Imaging 2011: Physics of Medical Imaging
Norbert J. Pelc; Ehsan Samei; Robert M. Nishikawa, Editor(s)

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