Nouvelle méthode spatio-spectrale de correction de la diffusion en tomographie à émission de positons

Abstract : We developed and validated a fast Monte Carlo simulation of PET acquisitions based on the SimSET program modeling accurately the propagation of gamma photons in the patient as well as the block-based PET detector. Comparison of our simulation with another well validated code, GATE, and measurements on two GE Discovery ST PET scanners showed that it models accurately energy spectra (errors smaller than 4.6%), the spatial resolution of block-based PET scanners (6.1%), scatter fraction (3.5%), sensitivity (2.3%) and count rates (12.7%). Next, we developed a novel scatter correction incorporating the energy and position of photons detected in list-mode. Our approach is based on the reformulation of the list-mode likelihood function containing the energy distribution of detected coincidences in addition to their spatial distribution, yielding an EM reconstruction algorithm containing spatial and energy dependent correction terms. We also proposed using the energy in addition to the position of gamma photons in the normalization of the scatter sinogram. Finally, we developed a method for estimating primary and scatter photons energy spectra from total spectra detected in different sectors of the PET scanner. We evaluated the accuracy and precision of our new spatio-spectral scatter correction and that of the standard spatial correction using realistic Monte Carlo simulations. These results showed that incorporating the energy in the scatter correction reduces bias in the estimation of the absolute activity level by ~60% in the cold regions of the largest patients and yields quantification errors less than 13% in all regions.
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Submitted on : Wednesday, September 1, 2010 - 7:00:40 AM
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Guérin Bastien. Nouvelle méthode spatio-spectrale de correction de la diffusion en tomographie à émission de positons. Biophysique [physics.bio-ph]. Université Pierre et Marie Curie - Paris VI, 2010. Français. ⟨tel-00488904⟩

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