A High-Resolution Semi-Monolithic Slab Detector tailored for Pre-Clinical PET

Current pre-clinical positron emission tomography (PET) scanners are often based on monolithic detectors due to their high spatial resolution and intrinsic depth-of-interaction (DOI) capabilities to reduce parallax positioning errors. However, the broad light distributions of monolithic designs can lead to drawbacks in the sensor readout and in the processing chain, e.g., dead time as well as pile up. Semi-monolithic slab detectors represent an attractive alternative as they provide a higher optical photon density while allowing a DOI determination. The cost can be assumed competitive with monoliths. This work presents a semi-monolithic detector comprising 1 mm thin high-resolution LYSO slabs coupled to a 12 × 12 channel digital SiPM tile. Currently, a detector spatial resolution (SR) (FWHM of the PSF) of 1.2 / 2.3 mm and a mean absolute error (MAE) of 0.9 / 1.1 mm is achieved in planar-monolithic / DOI direction with a correct slab identification in the planar-segmented direction of 92 % considering a [435 - 585] keV energy window. An energy resolution of 15.2 % and 461 ps coincidence timing resolution (CTR) were obtained.