27 August 1993 Comparison between ML-EM and modified Newton algorithms for SPECT image reconstruction
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Proceedings Volume 1887, Physiological Imaging, Spectroscopy, and Early-Detection Diagnostic Methods; (1993) https://doi.org/10.1117/12.151187
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States
Abstract
The expectation maximization method for maximum likelihood image reconstruction (ML- EM) is one of the most popular algorithms used in SPECT and PET, because it is based on the realistic assumption that photon emission and counts follow a Poisson process. Moreover, this method retains two important theoretical and practical properties namely nonnegativity and self-normalization of the reconstructed image. This latter property means that the number of emitted photons is equal to the number of counts. However, the major disadvantage of this method is the large amount of computation that is required, due to its slow rate of convergence. In this paper, we demonstrate that the ML-EM algorithm is a special case of the modified Newton method and can thus be accelerated by multiplying at each iteration the changes to the image, as calculated by the standard algorithm, by an overrelaxation parameter. This accelerated ML-EM algorithm can further be optimally accelerated, and converges to a good maximum likelihood estimator.
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Rita Noumeir, Rita Noumeir, Guy E. Mailloux, Guy E. Mailloux, Hail Mallouche, Hail Mallouche, Raymond Lemieux, Raymond Lemieux, } "Comparison between ML-EM and modified Newton algorithms for SPECT image reconstruction", Proc. SPIE 1887, Physiological Imaging, Spectroscopy, and Early-Detection Diagnostic Methods, (27 August 1993); doi: 10.1117/12.151187; https://doi.org/10.1117/12.151187
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