Comparison of Integral Reconstruction Methods in SPECT Based on Numerical Simulation of Detector’s Count by the Monte Carlo Method Using the Geant4 System

Scattering of radiation make the largest contribution to data distortion in SPECT. There is no algorithm to fully take into account the influence of scattering. This is due to the fact that emission tomography is based on the radiation transfer equation, which does not have an exact analytical solution in the general case. In this regard, various approximations are used. To study the accuracy of the reconstruction in various approximations, it is possible to use the numerical simulation of the detector data by the Monte Carlo method using the Geant4 system. The comparison was made between the traditional reconstruction method and the reconstruction method based on approximation of the "scattering straight back", which takes into the account the influence of scattering in the tomogram reconstruction. The numerical simulation was carried out for a heterogeneous scattering medium. The results obtained show the superiority of the proposed method over the traditional one.