New Detector Designs for High Resolution Brain PET

The goal of this work is to design a detector with ≤ 2 mm intrinsic resolution and multiple levels of depth of interaction (DOI), suitable for brain dedicated Positron Emission Tomography (PET). Our starting point is a 2 cm thick LYSO:Ce crystal with single-side readout, containing laser induced optical barriers (LIOB) in a simple pixel like pattern extending half-way through the crystal thickness. While this design is characterized by depth variation of the scintillation light spread in the detector, this dependence is complex due to the discontinuities in the design. Furthermore, the transversal resolution is limited in the unprocessed part of the scintillator where no optical barriers exist. In this work we are therefore exploring the possibility of enhancing performance beyond the basic design, by adding single photodetector elements to the sides and/or top of the scintillator. Our results show that the addition of side and/or top photodetectors can indeed improve DOI performance by providing more linear DOI curves, and the side photodetectors will provide additional XY information that can be exploited for improved positioning.