Solid-state detector stack for ToF-PET/MR

The integration of PET and MR imaging requires a novel type of highly integrated PET detector. To cope with geometric constraints and MR compliance a very compact detector stack was built within the HYPERImage consortium. This allows a four side buttable detector module design with a low dead space in between. The scintillation light coming from a LYSO array is converted in a SiPM sensor tile with a high packing fraction and a high photo detection efficiency to provide sub-ns time-of-flight timing resolution. The analog signals coming from the SiPM elements are digitized close to the sensor to minimize potential crosstalk. A custom mixed-signal ASIC was integrated on a 64 channel sensor stack which is powered and controlled by an FPGA interface board. The complete sensor stack is assembled and characterized to extract the PET relevant parameters, in particular energy, timing and spatial resolution for clinical and pre-clinical PET/MR applications.