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Proceedings Paper

An object-specific and dose-sparing scatter correction approach for a dedicated cone-beam breast CT system using a parallel-hole collimator
Author(s): Kai Yang; George Burkett Jr.; John M. Boone
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Paper Abstract

X-ray scatter is a common cause of image artifacts for cone-beam CT systems due to the expanded field of view and degrades the quantitative accuracy of measured Hounsfield Units (HU). Due to the strong dependency of scatter on the object being scanned, it is crucial to measure the scatter signal for each object. We propose to use a beam pass array (BPA) composed of parallel-holes within a tungsten plate to measure scatter for a dedicated breast CT system. A complete study of the performance of the BPA was conducted. The goal of this study was to explore the feasibility of measuring and compensating for the scatter signal for each individual object. Different clinical study schemes were investigated, including a full rotation scan with BPA and discrete projections acquired with BPA followed by interpolation for full rotation. Different sized cylindrical phantoms and a breast shaped polyethylene phantom were used to test for the robustness of the proposed method. Physically measured scatter signals were converted into scatter to primary ratios (SPRs) at discrete locations through the projection image. A complete noise-free 2D SPR was generated from these discrete measurements. SPR results were compared to Monte Carlo simulation results and scatter corrected CT images were quantitatively evaluated for "cupping" artifact. With the proposed method, a reduction of up to 47 HU of "cupping" was demonstrated. In conclusion, the proposed BPA method demonstrated effective and accurate objectspecific scatter correction with the main advantage of dose-sparing compared to beam stop array (BSA) approaches.

Paper Details

Date Published: 23 February 2012
PDF: 6 pages
Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 831303 (23 February 2012); doi: 10.1117/12.911093
Show Author Affiliations
Kai Yang, Univ. of California, Davis Medical Ctr. (United States)
George Burkett Jr., Univ. of California, Davis Medical Ctr. (United States)
John M. Boone, Univ. of California, Davis Medical Ctr. (United States)

Published in SPIE Proceedings Vol. 8313:
Medical Imaging 2012: Physics of Medical Imaging
Norbert J. Pelc; Robert M. Nishikawa; Bruce R. Whiting, Editor(s)

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