Development and characterization of high performance PET detectors

The main focus of my thesis is the investigation of new detectors with high spatial performance and depth of interaction capabilities, to overcome the actual limitations in resolution and to have more uniform performances in the whole scanner field of view. In my work I analyze a detection method based on a single monolithic crystal. The light is shared between multiple photo-sensors arranged on the two sides of the scintillator. I focus on the capability to reconstruct the depth of interaction of the events and on the problems related to the edge effects. I study a method to reduce the edge effect, based on the optical coupling of monolithic crystals in the scanner, and I demonstrate that events close to the optical interface can also be reconstructed with a minimal loss in resolution. The main limitations when using monolithic crystals in PET scanners are due to the difficulties in module calibration. In this respect I also study the performances of a detection architecture based on a pixelated crystal array with a double side read-out using rectangular orthogonal SiPMs strips to reduce the number of channels and to identify the single scintillator in a simple way. A calibration method is developed for the energy and the DOI measurements.