Exact and efficient computation of noise covariance for fan-beam FBP reconstructions that use rebinning to parallel-beam geometry

Adam Wunderlich; Frédéric Noo

doi:10.1117/12.910545

3 March 2012 Exact and efficient computation of noise covariance for fan-beam FBP reconstructions that use rebinning to parallel-beam geometry

Adam Wunderlich, Frédéric Noo

Author Affiliations +

Proceedings Volume 8313, Medical Imaging 2012: Physics of Medical Imaging; 831323 (2012) https://doi.org/10.1117/12.910545
Event: SPIE Medical Imaging, 2012, San Diego, California, United States

Abstract

X-ray CT data collected in fan-beam geometry is often rebinned to parallel-beam geometry before image reconstruction. In this work, we propose an exact, efficient method to analytically calculate the covariance between image pixels for an FBP reconstruction when such a rebinning step is performed. As a special case, the method also enables calculation of image variance. Our approach builds on a previous investigation of noise covariance for direct fan-beam FBP reconstruction, and encompasses commonly used variants of parallel-beam rebinning algorithms that include data interleaving steps to process fan-beam data acquired with either a quarter-detector offset or a flying focal spot. The accuracy of the variance and covariance calculation results is validated through comparison with Monte Carlo estimates.

Citation Download Citation

Adam Wunderlich and Frédéric Noo "Exact and efficient computation of noise covariance for fan-beam FBP reconstructions that use rebinning to parallel-beam geometry", Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 831323 (3 March 2012); https://doi.org/10.1117/12.910545

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