Monte Carlo simulation in SPECT: complete 3D modelling of source, collimator and tomographic data acquisition

A sophisticated SPECT (single photon emission computed tomography) simulation package was developed permitting full tomographic acquisition of data from physically realistic nonuniform and asymmetric 3-D source objects. The package is based on the Los Alamos code MCNP (Monte Carlo for neutron-photon transport), which was extensively modified to allow complete collimator and source modeling and direct manipulation of the geometric and physical parameters of the nuclear medicine experiment. A description of the synthetic SPECT imaging system and of its capabilities is given. MCNP is described, and details of the modifications that were necessary in order to run MCNP for this application are provided. Preliminary experiments to verify the accurate modeling of the imaging situation were successful. The focus is on its ability to model two different collimator geometries (parallel-hole and cone-beam). Steps taken to verify the models are discussed.<>