Geometric model of single scatter in PET

We present a mathematical model of single scatter in PET for a detector system possessing excellent energy resolution. Derivation of the model exploits assumptions widely used in PET and SPECT modalities for unscattered photons forward modeling. Integral equations describing a flux of photons emanating from the same annihilation event and undergoing a single scattering with a certain angle are derived in both 2D and 3D cases. Preliminary results of numerical experiments are presented.