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Proceedings Paper

X-ray spectrum estimation from transmission measurements by an exponential of a polynomial model
Author(s): Boris Perkhounkov; Jessika Stec; Emil Y. Sidky; Xiaochuan Pan
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Paper Abstract

There has been much recent research effort directed toward spectral computed tomography (CT). An important step in realizing spectral CT is determining the spectral response of the scanning system so that the relation between material thicknesses and X-ray transmission intensity is known. We propose a few parameter spectrum model that can accurately model the X-ray transmission curves and has a form which is amenable to simultaneous spectral CT image reconstruction and CT system spectrum calibration. While the goal is to eventually realize the simultaneous image reconstruction/spectrum estimation algorithm, in this work we investigate the effectiveness of the model on spectrum estimation from simulated transmission measurements through known thicknesses of known materials. The simulated transmission measurements employ a typical X-ray spectrum used for CT and contain noise due to the randomness in detecting finite numbers of photons. The proposed model writes the X-ray spectrum as the exponential of a polynomial (EP) expansion. The model parameters are obtained by use of a standard software implementation of the Nelder-Mead simplex algorithm. The performance of the model is measured by the relative error between the predicted and simulated transmission curves. The estimated spectrum is also compared with the model X-ray spectrum. For reference, we also employ a polynomial (P) spectrum model and show performance relative to the proposed EP model.

Paper Details

Date Published: 1 April 2016
PDF: 4 pages
Proc. SPIE 9783, Medical Imaging 2016: Physics of Medical Imaging, 97834W (1 April 2016); doi: 10.1117/12.2217100
Show Author Affiliations
Boris Perkhounkov, Stanford Univ. (United States)
Jessika Stec, DePaul Univ. (United States)
Emil Y. Sidky, The Univ. of Chicago Medical Ctr. (United States)
Xiaochuan Pan, The Univ. of Chicago Medical Ctr. (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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