OVERSAMPLED FILTERS FOR QUANTITATIVE VOLUMETRIC PET RECONSTRUCTION

Three-dimensional filtered backprojection uses filters generally speci fied in the Fourier domain. Implementing these filters by direct sampl ing in the Fourier domain produces an artifact in the reconstructed im ages consisting primarily of a DC shift. This artifact is caused by al iasing of the reconstruction filter. We have developed a filter constr uction technique using Fourier domain oversampling, which reduces the artifact. A method to construct the filter efficiently without the nee d to create and store the entire oversampled filter array is also pres ented. Quantitative accuracy in filtered backprojection is of particul ar importance in multiple-pass algorithms used to reconstruct data fro m cylindrical PET scanners. We are able to implement such algorithms w ithout fitting the reprojected views to the scanner data.