
Proceedings Paper
Efficient scatter correction using asymmetric kernelsFormat | Member Price | Non-Member Price |
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Paper Abstract
X-ray cone-beam (CB) projection data often contain high amounts of scattered radiation, which must be properly
modeled in order to produce accurate computed tomography (CT) reconstructions. A well known correction technique is
the scatter kernel superposition (SKS) method that involves deconvolving projection data with kernels derived from
pencil beam-generated scatter point-spread functions. The method has the advantages of being practical and
computationally efficient but can suffer from inaccuracies. We show that the accuracy of the SKS algorithm can be
significantly improved by replacing the symmetric kernels that traditionally have been used with nonstationary
asymmetric kernels. We also show these kernels can be well approximated by combinations of stationary kernels thus
allowing for efficient implementation of convolution via FFT. To test the new algorithm, Monte Carlo simulations and
phantom experiments were performed using a table-top system with geometry and components matching those of the
Varian On-Board Imager (OBI). The results show that asymmetric kernels produced substantially improved scatter
estimates. For large objects with scatter-to-primary ratios up to 2.0, scatter profiles were estimated to within 10% of
measured values. With all corrections applied, including beam hardening and lag, the resulting accuracies of the CBCT
reconstructions were within ±25 Hounsfield Units (±2.5%).
Paper Details
Date Published: 12 March 2009
PDF: 12 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72581Z (12 March 2009); doi: 10.1117/12.811578
Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)
PDF: 12 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72581Z (12 March 2009); doi: 10.1117/12.811578
Show Author Affiliations
Josh Star-Lack, Varian Medical Systems, Inc. (United States)
Mingshan Sun, Varian Medical Systems, Inc. (United States)
Anders Kaestner, Varian Medical Systems AG (Switzerland)
Rene Hassanein, Varian Medical Systems AG (Switzerland)
Mingshan Sun, Varian Medical Systems, Inc. (United States)
Anders Kaestner, Varian Medical Systems AG (Switzerland)
Rene Hassanein, Varian Medical Systems AG (Switzerland)
Gary Virshup, Varian Medical Systems, Inc. (United States)
Timo Berkus, Varian Medical Systems AG (Switzerland)
Markus Oelhafen, Varian Medical Systems AG (Switzerland)
Timo Berkus, Varian Medical Systems AG (Switzerland)
Markus Oelhafen, Varian Medical Systems AG (Switzerland)
Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)
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