An analytical model for Compton scatter in a homogeneously attenuating medium

Accurate reconstruction of SPECT images is hampered by four nonlinear effects in the acquisition process: attenuation, scatter, collimator acceptance angle, and statistical noise. A good mathematical description of these effects is obviously crucial for the reconstruction. Poisson noise, attenuation, and collimator acceptance angle are relatively easy to model. Scattering, however, is a very complex process, and is mostly described using empirical models. A new model for the scatter point spread function in a homogeneous medium that is based on physical considerations and is capable of predicting scatter contributions of point sources as a function of depth in homogeneous media is presented. The model is verified with Monte Carlo simulations and line source measurements, and is compared to an existing empirical model