Modeling of Single Photon Avalanche Diode Array Detectors for PET Applications

We developed a configurable model of single photon avalanche diodes (SPAD) array photodetectors with intelligent control and active quenching. In this model individual components can be simulated independently and subsequently linked to provide the overall detector response. The model enables the simulation of the entire detector and analysis of performance, including photon detection efficiency, timing and energy resolution. It can be used to optimize detector performance for specific applications, such as positron emission tomography (PET). The simulator consists of multiple configurable and interchangeable modules to model the array geometry as well as physical and optical characteristics based on physical models and statistical equations. Readout electronics are also simulated in an algorithmic form. Monte Carlo simulations are used to model the 511 keV annihilation photon interactions and the optical photon transport in the scintillator, as well as carrier random walk in the silicon. Different methods to extract information from the digital output signal can be investigated. The simulator paves the way to the developement of new algorithms to extract relevant information in PET, but also for other applications such as Cerenkov radiation and fluorescence microscopy. Simulation results for photon detection efficiency, energy resolution and timing resolution are reported, showing the functionality of the simulator.