Analytical calculation of scatter distributions in SPECT projections

The authors present a method for quantitatively determining the scatter in nonhomogeneous media by analytically transporting photons through the media. This technique permits a patient specific estimation of the scatter distribution. The scatter is computed using a precalculated camera-dependent lookup table in conjunction with an attenuation map of the scattering object and a map of the activity distribution. The authors validate this technique by comparison with Monte Carlo simulations for a point source in homogeneous and nonhomogeneous scattering media and for an extended source in a nonhomogeneous medium. The authors find that their approach is quantitatively accurate to better than 8 percent of the Monte Carlo results and faithfully reproduces the spatial distribution of the scattered photons