Projection space image reconstruction using strip functions to calculate pixels more “natural” for modeling the geometric response of the SPECT collimator

The spatially varying geometric response of the collimator-detector system in SPECT produces loss in resolution in addition to shape distortions, reconstructed density non-uniformity and quantitative inaccuracies. A projection space image reconstruction with projectors that use strip functions to calculate pixels more “natural” for modeling the geometric response of the SPECT collimator is used to correct these reconstruction artifacts. Two projection models were evaluated for modeling the system geometric response function. For one projector each strip is of equal weight, whereas for the other a Gaussian weighting is used. Fan beam projection of a physical Hoffman brain phantom was used to evaluate the geometric response correction. Reconstructions produced by the two proposed projectors showed improved resolution when compared against a unit-strip “natural” pixel model and the filtered backprojection algorithm