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Proceedings Paper

Enhancement of mobile C-arm cone-beam reconstruction using prior anatomical models
Author(s): Ofri Sadowsky; Junghoon Lee; Edward Grant Sutter; Simon J Wall; Jerry L. Prince; Russell H. Taylor
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Paper Abstract

We demonstrate an improvement to cone-beam tomographic imaging by using a prior anatomical model. A protocol for scanning and reconstruction has been designed and implemented for a conventional mobile C-arm: a 9 inch image-intensifier OEC-9600. Due to the narrow field of view (FOV), the reconstructed image contains strong truncation artifacts. We propose to improve the reconstructed images by fusing the observed x-ray data with computed projections of a prior 3D anatomical model, derived from a subject-specific CT or from a statistical database (atlas), and co-registered (3D/2D) to the x-rays. The prior model contains a description of geometry and radiodensity as a tetrahedral mesh shape and density polynomials, respectively. A CT-based model can be created by segmentation, meshing and polynomial fitting of the object's CT study. The statistical atlas is created through principal component analysis (PCA) of a collection of mesh instances deformably-registered (3D/3D) to patient datasets. The 3D/2D registration method optimizes a pixel-based similarity score (mutual information) between the observed x-rays and the prior. The transformation involves translation, rotation and shape deformation based on the atlas. After registration, the image intensities of observed and prior projections are matched and adjusted, and the two information sources are blended as inputs to a reconstruction algorithm. We demonstrate recostruction results of three cadaveric specimens, and the effect of fusing prior data to compensate for truncation. Further uses of hybrid reconstruction, such as compensation for the scan's limited arc length, are suggested for future research.

Paper Details

Date Published: 13 March 2009
PDF: 12 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72585B (13 March 2009); doi: 10.1117/12.813405
Show Author Affiliations
Ofri Sadowsky, The Johns Hopkins Univ. (United States)
Junghoon Lee, The Johns Hopkins Univ. (United States)
Edward Grant Sutter, International Ctr. for Orthopaedic Advancement, The Johns Hopkins Bayview Medical Ctr. (United States)
Simon J Wall, International Ctr. for Orthopaedic Advancement, The Johns Hopkins Bayview Medical Ctr. (United States)
Jerry L. Prince, The Johns Hopkins Univ. (United States)
Russell H. Taylor, The Johns Hopkins Univ. (United States)

Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)

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