Preliminary experimental results of a quasi-monolithic detector with DOI capability for a small animal PET

In our previous work, the new detector module with depth of interaction (DOI) based on a quasi-monolithic crystal array and maximum-likelihood position-estimation (MLPE) algorithm was designed and the methodology for 3D event positioning in the detector was established by using Monte Carlo simulation. The aim of this study was to evaluate the performance of our detector module experimentally. The detector module consisted of a 1D array of eight LYSO crystals of 2.0 (axial) × 20.0 (trans-axial) × 10.0 (depth) mm³ optically coupled to a Hamamatsu H7546B flat panel position sensitive photomultiplier tube (PSPMT). The PSPMT was read out using a resistive charge divider, which multiplexes 64 anodes into 8(X) + 8(Y) channels. Gaussian-based MLPE methods have been implemented using experimentally measured detector response functions (DRFs). The results demonstrated that the detector module could identify the position of the gamma ray interaction inside the crystal with a resolution of 2.0 mm in all three directions. The new DOI detector for a small animal PET was developed and verified experimentally with a view towards achieving high sensitivity as well as high and uniform radial resolution.