
Proceedings Paper
A Poisson likelihood iterative reconstruction algorithm for material decomposition in CTFormat | Member Price | Non-Member Price |
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Paper Abstract
Emerging photon-counting detectors with energy discrimination ability for x-ray CT perform binning according
to the energy of the incoming photons. Multiple output channels with different energy thresholds can be obtained
in one irradiation. The energy dependency of attenuation coefficients can be described by a linear combination
of basis functions, e.g., Compton scatter and photo-electric effect; their individual contributions can be differentiated
by using the multiple energy channels hence material characterization is made possible. Conventional
analytic approach is a two-step process. First decompose in the projection domain to obtain the sinograms
corresponding to the coefficients of the basis functions, then apply FBP to obtain the individual material components.
This two-step process may have poor quality and quantitative accuracy due to the lower counts in the
separate energy channels and approximation errors propagated to the image domain from projection domain
decomposition. In this work we modeled the energy dependency of linear attenuation coefficients in our problem
formulation and applied the optimality transfer principle to derive a Poisson-likelihood based algorithm for
material decomposition from multiple energy channels. Our algorithm reconstructs the coefficients of the basis
functions directly therefore the separate non-linear estimation step in the projection domain as in conventional
approaches is avoided. We performed simulations to study the accuracy and noise properties of our method.
We synthesized the linear attenuation coefficients at a reference energy and compared with standard attenuation
values provided by NIST. We also synthesized the attenuation maps at different effective energy bin centers
corresponding to the different energy channels and compared the synthesized images with reconstructions from
standard fan-beam FBP methods. Preliminary simulations showed that our reconstructed images have much better noise properties.
Paper Details
Date Published: 16 March 2007
PDF: 6 pages
Proc. SPIE 6510, Medical Imaging 2007: Physics of Medical Imaging, 65101Z (16 March 2007); doi: 10.1117/12.713727
Published in SPIE Proceedings Vol. 6510:
Medical Imaging 2007: Physics of Medical Imaging
Jiang Hsieh; Michael J. Flynn, Editor(s)
PDF: 6 pages
Proc. SPIE 6510, Medical Imaging 2007: Physics of Medical Imaging, 65101Z (16 March 2007); doi: 10.1117/12.713727
Show Author Affiliations
Katsuyuki Taguchi, Johns Hopkins Univ. (United States)
Benjamin M. W. Tsui, Johns Hopkins Univ. (United States)
Benjamin M. W. Tsui, Johns Hopkins Univ. (United States)
Published in SPIE Proceedings Vol. 6510:
Medical Imaging 2007: Physics of Medical Imaging
Jiang Hsieh; Michael J. Flynn, Editor(s)
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