Simulation of a single photon emission computed tomography focusing collimator system

A computer program to simulate the three dimensional impulse response of a convergent focus rectangular tube collimator system has been developed. The simulation is done by a deterministic algorithm that models geometric acceptance of photons, photon penetration of the septa, and single scatter interactions in the collimator walls. Output from the simulator is used as a basis set for the impulse response of a multiple detector SPECT system. The basis set is used by fitting procedures that estimate the impulse response of the Donner SPECT system (12 angles, 12 x 128 detector positions per angle) from noisy measurements of a point source. These impulse response estimates are used to determine the weighting matrix of new emission reconstruction algorithms