Fast GATE multi-pinhole SPECT simulations

Multi-pinhole collimation is increasingly being used in SPECT imaging. A wide variety of geometric designs has recently been introduced, which can easily be modeled with the Monte Carlo simulator GATE. However multi-pinhole simulations are still very inefficient with GATE due to the lack of a dedicated variance reduction technique. In this work, we introduced a pinhole forced detection method which allows for fast ^99mTc GATE multi-pinhole simulations. An excellent agreement with analog GATE simulations was found in terms of spatial resolution, energy spectra, sensitivity and collimator penetration. As the collimator-detector response is modeled with full Monte Carlo - without making any assumptions on the detector configuration - our method can be of use in multi-pinhole collimator design, development of compensation methods and image reconstruction.