SPATIAL PROPERTIES OF THE SCATTER RESPONSE FUNCTION IN SPECT

Previously we have shown that the scatter response function (SRF) in SPECT imaging can be fit using a fitting function consisting of the sum of a Gaussian and two half Gaussians with different widths. In this work we have studied the fitting parameters as a function of source position in a cylindrical water filled phantom for a low resolution (LR), high sensitivity collimator. We have 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 (LEGP) collimator we have found that it may be more useful to parameterize the SRF as the product or other function of the SRF for a semi-infinite 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.