Performance evaluation of an advanced detector module for an RF-penetrable TOF-PET insert for simultaneous PET/MRI

Simultaneous PET/MRI, which combines molecular and anatomical assessment, is a promising multi-modality imaging method. However, the high cost of the current commercial integrated PET/MRI systems limits the long-term potential of PET/MRI imaging. We are studying designs of a PET ring that can be inserted into existing MRI systems in order to reduce the cost without affecting the performance of either the PET or MRI components by leveraging the existing MR infrastructure. We are developing a second-generation RF-penetrable brain-dedicated TOF-PET insert with a trans-axial and axial FoVs of 28 cm and 16 cm, respectively. The PET ring comprises 16 detector modules, each hosting 6 sub-modules. Each sub-module comprises an array of 8 × 16 LYSO crystal elements (3.2 × 3.2 × 20 mm
³
) one-to-one coupled to an array of SiPMs read out by 4 36-channel readout ASICs. In this work, we evaluated the energy and coincidence timing resolution performance of a detector module, which was thermally regulated by a liquid chiller system at 30 degrees Celsius during the experiments. The energy resolution at 511 keV measured for 256 channels of two sub-modules is 14.3 ± 1.6% (mean ± standard deviation) and coincidence timing resolution measured over two sub-modules is 261.2 ± 28.5 ps FWHM.