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Descripción
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| High resolution PET/CT tomographs provide anatomical CT images of small rodents co-registered with functional data. We present an algorithm for the reconstruction of PET images using the CT anatomical data to regularize the fully-3D OS-EM algorithm and correct for the attenuation effect. The penalty term is weighted by the cross¿entropy between the prior image and an anatomical edge¿preserving smoothed version of the previous iteration result. The penalty term reduces the noise amplification, which is a drawback of iterative OS-EM reconstruction algorithm, and improves edge resolution where anatomical variations exist, showing robustness against misalignments or other errors in the CT data. The attenuation correction factors are calculated by mapping the CT photon energy image to PET photon energy, followed by a forward projection with the same system matrix coefficients used in the reconstruction process. A 3D efficient implementation has been developed for a high resolution PET scanner composed of rotating planar detectors. The associated system matrix is precalculated with Monte Carlo methods that simulate physical effects not included in analytical models. The scanner geometry allows the use of axial and transaxial symmetries, and only the non¿zero system matrix elements belonging to one quadrant of a central transaxial slice need to be precalculated and stored in sparse matrix format. | |
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Internacional
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Si |
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Nombre congreso
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9th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine |
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Tipo de participación
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960 |
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Lugar del congreso
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Lindau, Alemania |
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Revisores
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Si |
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ISBN o ISSN
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DOI
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Fecha inicio congreso
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09/07/2007 |
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Fecha fin congreso
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13/07/2007 |
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