In this paper, the authors review the field of parallax error (PE) minimization in positron emission tomography (PET) imaging systems by using depth of interaction (DOI) capable concepts. The review includes apparatus as well as an overview of various methods described in the literature. It also discusses potential advantages gained via these approaches, as discussed with reference to various metrics and tasks, particularly in the improvement of spatial resolution (SR) performance. Furthermore, the authors emphasize limitations encountered in the context of DOI decoding, which can be a considerable pitfall depending on the task of interest.

Charging-up processes affecting gain stability in Thick Gas Electron Multipliers (THGEM) were studied with a dedicated simulation toolkit. Integrated with Garfield++, it provides an effective platform for systematic phenomenological studies of charging-up processes in MPGD detectors. We describe the simulation tool and the fine-tuning of the step-size required for the algorithm convergence, in relation to physical parameters. Simulation results of gain stability over time in THGEM detectors are presented, exploring the role of electrode-thickness and applied voltage on its evolution. The results show that the total amount of irradiated charge through electrode's hole needed for reaching gain stabilization is in the range of tens to hundreds of pC, depending on the detector geometry and operational voltage. These results are in agreement with experimental observations presented previously.