FastMIST: A Fast Molecular Imaging SimulaTor

The Fast Molecular Imaging SimulaTor (FastMIST) is a hybrid analytical/Monte Carlo code which can simulate almost any arbitrary time-varying source distribution. Additionally, the position of each event can be spatially transformed according to a predefined temporal motion pattern allowing for the simulation of motion-corrupted data. The core algorithms are implemented in C++ following a modular design that is readily parallelisable using OpenMP. The execution time for a FastMIST simulation is greatly reduced compared to a full Monte Carlo simulation, such as GATE, as FastMIST uses forced detection coupled to random sampling of experimentally measured depth-dependent PSFs for parallel hole collimators. A FastMIST simulation of a parallel-hole collimator gamma camera, acquiring 300k photons per projection (64 projections) with source attenuation modelling disabled, took less than 30 seconds on an 15 Intel processor (2.4Ghz).