Iterative transmission reconstruction for collimated coincidence point sources in rotating PET systems

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Abstract
Previous publications introduced an array of collimated coincidence point sources for transmission imaging in PET. The design of the point source array matches transmission lines-of- response with emission ones in direct planes. The attenuation map is reconstructed front transmission projection data collected with single slice rebinning and nearest neighbor approximation imposed by the matching with emission acquisition geometry. Since transmission measurements are performed with an axially focused converging geometry, the goal of this work is to investigate potential improvements in attenuation map reconstruction by using an iterative cone beam reconstruction whose parameters depend on number of sources, source position and collimator design. By using Defrise's and anthropomorphic phantoms we demonstrated that iterative cone beam reconstruction improves axial resolution in the region between point sources when compared with present data processing.