The use of multiple-pinhole coded apertures in single-photon emission computed tomographic (SPECT) systems makes possible SPECT geometries that image from multiple directions simultaneously and that have greater photon-collection efficiencies than conventional SPECT systems. However, the multiplexing of data that results from the use of such apertures is not well understood and, therefore, is not always optimally decoded. Presented in this paper are results from a simulation study of multiple-pinhole coded-aperture systems having pinholes that are uniformly spaced and of uniform width. Five apertures representing varying degrees of multiplexing are considered, and the results presented are in the form of pictorial displays that make possible qualitative comparisons of images from the five imaging systems. Shown are representations of the Hoffman brain phantom determined following singular value decompositions of the system matrices and reconstructions of simulated SPECT data using a Monte Carlo algorithm and prior information.
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