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Proceedings Paper

Rapid scatter estimation for CBCT using the Boltzmann transport equation
Author(s): Mingshan Sun; Alex Maslowski; Ian Davis; Todd Wareing; Gregory Failla; Josh Star-Lack
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Paper Abstract

Scatter in cone-beam computed tomography (CBCT) is a significant problem that degrades image contrast, uniformity and CT number accuracy. One means of estimating and correcting for detected scatter is through an iterative deconvolution process known as scatter kernel superposition (SKS). While the SKS approach is efficient, clinically significant errors on the order 2-4% (20-40 HU) still remain. We have previously shown that the kernel method can be improved by perturbing the kernel parameters based on reference data provided by limited Monte Carlo simulations of a first-pass reconstruction. In this work, we replace the Monte Carlo modeling with a deterministic Boltzmann solver (AcurosCTS) to generate the reference scatter data in a dramatically reduced time. In addition, the algorithm is improved so that instead of adjusting kernel parameters, we directly perturb the SKS scatter estimates. Studies were conducted on simulated data and on a large pelvis phantom scanned on a tabletop system. The new method reduced average reconstruction errors (relative to a reference scan) from 2.5% to 1.8%, and significantly improved visualization of low contrast objects. In total, 24 projections were simulated with an AcurosCTS execution time of 22 sec/projection using an 8-core computer. We have ported AcurosCTS to the GPU, and current run-times are approximately 4 sec/projection using two GPU’s running in parallel.

Paper Details

Date Published: 19 March 2014
PDF: 9 pages
Proc. SPIE 9033, Medical Imaging 2014: Physics of Medical Imaging, 90330Z (19 March 2014); doi: 10.1117/12.2043312
Show Author Affiliations
Mingshan Sun, Varian Medical Systems, Inc. (United States)
Alex Maslowski, Transpire, Inc. (United States)
Ian Davis, Transpire, Inc. (United States)
Todd Wareing, Transpire, Inc. (United States)
Gregory Failla, Transpire, Inc. (United States)
Josh Star-Lack, Varian Medical Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 9033:
Medical Imaging 2014: Physics of Medical Imaging
Bruce R. Whiting; Christoph Hoeschen, Editor(s)

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