Abstract
The utilization of non-pure positron emitting nuclides with complex decay characteristics for animal molecular imaging raises several questions about their ability to perform high quality imaging. Monte Carlo simulation is a powerful tool to accurately quantify the micoPET images with these non-pure positron emitters. SimSET (Simulation System for Emission Tomography) is an efficient Monte Carlo code, but it’s limited in terms of the versatile detector simulation and the support of non-pure positron emitters. GATE (Geant4 application for tomographic emission) based on GEAN4 offers the ability and the flexibility to model novel detection systems but are not efficient at voxel-based phantoms. In order to accurately model the scanner systems and maintain the efficient simulation speed as well, our purpose is to develope an efficient and realistic Monte Carlo simulation for non-pure positron emitters with SimSET-GATE workflow (SimGATE). The current SimSET software didn’t provide the time information and the simulation of non-pure positron emitters. In order to perform the complex decay scheme of non-pure positron emitter, we modified the SimSET photon history generator (PHG) to support the non-pure positron emitters. The modified SimSET PHG was inserted into the GATE simulation to evade the relatively slow MCS code based on GEANT4 in simulating photon interactions inside voxelized phantoms. For validation, acquisitions of F-18, Cu-64 line source for different positions in a water phantom were performed with MicroPET R4 scanner, together with the corresponding simulations. Energy spectra, sensitivity and images with I-124 line source obtained from SimGATE and GATE were compared. Preliminary results indicated that the modified SimSET PHG version with SimSET-GATE workflow for these positron emitters are in rather good agreement between experimental and simulated resolution in different radial positions. Excellent agreement in spectra and different count rates were found between GATE–only and the new workflow as well. In summary, our new model allows fast and accurate modeling of microPET acquisition for the non-pure positron emitter. In the future study, we will explore the possibility of fully Monte Carlo simulation to correct all the non-true coincidences for the non-pure positron emitter.