Spatial properties of the scatter response function in SPECT

It was previously shown by the authors (ibid., vol.37, no.3, p.1308-15, 1990) that the scatter response function (SRF) in single photon emission computed tomography (SPECT) imaging can be fit using a fitting function consisting of the sum of a Gaussian and two half-Gaussians with different widths. In the present work, the fitting parameters are studied as a function of source position in a cylindrical water-filled phantom for a low-resolution (LR), high-sensitivity collimator. It is found that each fitting parameter can be described in terms of a single geometric parameter. The useful parameters include the source depth and the distance to the edge of the phantom. However, for a low-energy general-purpose collimator, it may be more useful to parameterize the SRF as the product or other function of the SRF for a semiinfinite slab, and an aperture function which depends on the shape of the surface of the phantom. This parameterization of the SRF is useful for scatter compensation in SPECT.<
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