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Proceedings Paper

Deblurring in iterative reconstruction of half CBCT for image guided brain radiosurgery
Author(s): SayedMasoud Hashemi; Young Lee; Markus Eriksson; Håkan Nordström; Bongyong Song; Wooseok Nam; Arjun Sahgal; William Song; Mark Ruschin
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Paper Abstract

A high spatial resolution iterative reconstruction algorithm is proposed for a half cone beam CT (HCBCT) geometry. The proposed algorithm improves spatial resolution by explicitly accounting for image blurriness caused by different factors, such as extended X-ray source and detector response. The blurring kernel is estimated using the MTF slice of the Catphan phantom. The proposed algorithm is specifically optimized for the new Leksell Gamma Knife Icon (Elekta AB, Stockholm, Sweden) which incorporates the HCBCT geometry to accommodate the existing treatment couch while covering down to the base-of-skull in the reconstructed field-of-view. Image reconstruction involves a Fourier-based scaling simultaneous algebraic reconstruction technique (SART) coupled with total variation (TV) minimization and non-local mean denoising, solved using a split Bregman separation technique that splits the reconstruction problem into a gradient based updating step and a TV-based deconvolution algorithm. This formulation preserves edges and reduces the staircase effect caused by regular TV-penalized iterative algorithms. Our experiments indicate that our proposed method outperforms the conventional filtered back projection and TV penalized SART methods in terms of line pair resolution and retains the favorable properties of the standard TV-penalized reconstruction.

Paper Details

Date Published: 29 March 2016
PDF: 9 pages
Proc. SPIE 9783, Medical Imaging 2016: Physics of Medical Imaging, 97832T (29 March 2016); doi: 10.1117/12.2216301
Show Author Affiliations
SayedMasoud Hashemi, Sunnybrook Research Institute (Canada)
Young Lee, Sunnybrook Research Institute (Canada)
Univ. of Toronto (Canada)
Markus Eriksson, Elekta AB (Sweden)
Håkan Nordström, Elekta AB (Sweden)
Bongyong Song, Univ. of California, San Diego (United States)
Wooseok Nam, Sunnybrook Research Institute (Canada)
Arjun Sahgal, Sunnybrook Research Institute (Canada)
Univ. of Toronto (Canada)
William Song, Sunnybrook Research Institute (Canada)
Univ. of Toronto (Canada)
Mark Ruschin, Sunnybrook Research Institute (Canada)
Univ. of Toronto (Canada)

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

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