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ST: Fachverband Strahlen- und Medizinphysik

ST 2: Medical Imaging Concepts

ST 2.2: Talk

Tuesday, March 21, 2023, 17:15–17:30, ZEU/0146

Investigation of the prospects of BaF2 as a fast scintillator for TOF-PET — •Katrin Herweg, Vanessa Nadig, Volkmar Schulz, and Stefan Gundacker — Department of Physics of Molecular Imaging Systems, RWTH Aachen University, Aachen, Germany

Future time-of-flight positron emission tomography (TOF-PET) will be in need of ultra-fast scintillation, with potential seen in cross-luminescencent materials like BaF2, which shows a sub-100ps decay time with 300 photons produced per MeV. However, it poses challenges such as medium radiation length, low photofraction, moderate light yield and VUV emission around 200nm. A slow emission at 310nm presents an additional challenge, which has been addressed before by doping BaF2 with yttrium. Recent developments in UV-sensitive SiPMs (here manufactured by Hamamatsu) have the potential to establish cross-luminescence for ultrafast TOF in PET. In this work, we aim to study BaF2, read out by these new VUV SiPMs, as a viable alternative to LYSO:Ce:Ca. Comparing the coincidence time resolution (CTR) of air-coupled 2 x 2 x 20mm3 undoped and yttrium-doped BaF2 crystals to LYSO:Ce:Ca crystals of the same size, with high-frequency readout electronics, we reached 233ps with undoped BaF2 and 213ps with BaF2:Y. The performance of LYSO:Ce:Ca was 181ps with Hamamatsu SiPMs optimized for LYSO. Conducting measurements at different depth of interaction positions shows a pronounced impact on the CTR. Furthermore, we investigated the performance for systems of BaF2 with TOFPET2c ASIC measurements and Geant4 simulations for effective sensitivity comparisons to LYSO:Ce:Ca.