MONTE-CARLO SIMULATION IN SPECT - COMPLETE 3D-MODELING OF SOURCE, COLLIMATOR AND TOMOGRAPHIC DATA ACQUISITION

A sophisticated SPECT simulation package has been developed permitting full tomographic acquisition of data from physically realistic nonuniform and asymmetric 3D source objects. The package is based on the Los Alamos code MCNP [1] (Monte Carlo for Neutron-Photon transport) which has been extensively modified by us to allow complete collimator and source modelling and direct manipulation of the geometric and physical parameters of the nuclear medicine experiment. In this paper we present a brief description of synthetic SPECT imaging system and of its capabilities. We will begin by describing the code MCNP, then we will provide details of the modifications that have been necessary in order to run MCNP for this application. Preliminary experiments to verify the accurate modelling of the imaging situation have been successful and these will also be described. We will focus here on its ability to model two different collimator geometries (parallel-hole and cone-beam), and include steps taken to verify the models.