Unified description and validation of Monte Carlo simulators in PET

Several Monte Carlo simulators are currently available for Positron Emission Tomography (PET). Because each code has been described in a specific way, it is difficult to know which one is best suited to a specific application. To help clarify the specificities and accuracy of different codes, we propose a uniform description of the code features. This description specifies features pertaining to the models used for simulating the physics of PET and describing a PET acquisition, to the acceleration strategies and to the technical characteristics of the code implementation. To assess the code accuracy, we suggest validation procedures based on NEMA phantoms involving standard physical parameters and simulation of a complex activity distribution. A test characterizing the statistical properties of simulated events is also described. The proposed code description and validation procedures are illustrated by considering the SimSET and PET-EGS codes. Despite the numerous differences between these 2 codes as demonstrated by the unified description of the codes, both codes yielded data with properties close to those of real data. Depending on the intended application, one code might be preferred however as the underlying physical models and computer efficiency differ significantly. The proposed code description and validation procedures might help determine which code is best appropriate for a specific application.