Commissioning of a 2048 element 3γ PET demonstrator

In this thesis a new 2048 element Lutetium-Yttrium Oxyorthosilicate (LYSO) based gamma detection array and associated data acquisition, simulation, and data analysis methodologies are commissioned. The array is employed for the first time in measurements, detecting radiation from the annihilation of 18F positrons in a range of media with different mean pore volumes. The annihilation site is reconstructed using a novel methodology that directly localises the 3γ decay of ortho-Positronium on an event-by-event basis. This methodology was developed by our group in collaboration with the University of Tokyo (Fujimoto et al., 2026). Standard 2γ reconstruction is also implemented, including the use of a Maximum Likelihood Expectation Maximisation (MLEM) approach. A first extraction of spatially resolved 3γ/2γ decay annihilation maps and ratios is obtained for the system using data employing a range of mesoporous annihilating media.