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13 March 2009 Simultaneous activity and attenuation reconstruction in PET: applying partially known attenuation
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Proceedings Volume 7258, Medical Imaging 2009: Physics of Medical Imaging; 72582F (2009)
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States
Simultaneous reconstruction of activity and attenuation in positron emission tomography without transmission data presents significant degradation due to crosstalk effect. The objective of this work is to investigate the effect of applying a priori knowledge, such as known attenuation coefficients, in some regions of the image, into a simultaneous activity and attenuation reconstruction algorithm (EM-AA). The methodology consists of applying, after each iteration, a global correction (addition) on the attenuation map, based on the difference between the known attenuation coefficient and the average of the estimated coefficients in the region. We also applied a correction factor that decreases with iteration number. The assessments were carried out via phantoms emulating 3D PET that presented specific features for crosstalk and structural accuracy measurements. We obtained three figures of merit for activity and three for attenuation. The results showed that, in the case of noiseless projections, the proposed correction improved the estimation of both activity and attenuation. On the other hand, while structural accuracy improved with iterations, the crosstalk effects become worse. The improvements were more pronounced for structural accuracy than for crosstalk effects. However, the errors are still too high, and more research is needed in this area.
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Sergio S. Furuie "Simultaneous activity and attenuation reconstruction in PET: applying partially known attenuation", Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72582F (13 March 2009);

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