ORIGINAL RESEARCH article
Front. Phys.
Sec. Medical Physics and Imaging
Volume 13 - 2025 | doi: 10.3389/fphy.2025.1603556
This article is part of the Research TopicAdvancements in instrumentation and detector modeling for TOF-based medical imagingView all articles
Analyzing the time distribution of external cross-talk for an SiPM-based TOF-PET detector
Provisionally accepted
- 1Institute of Imaging and Computer Vision, RWTH Aachen University, Aachen, Germany
- 2University Hospital RWTH Aachen, Aachen, Germany
- 3Fraunhofer Institute for Digital Medicine (MEVIS), Bremen, Bremen, Germany
- 4Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany
- 5Institute of High Energy Physics, Austrian Academy of Sciences (OeAW), Vienna, Vienna, Austria
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In the pursuit of developing the fastest time-offlight positron emission tomography (ToF-PET) detectors, understanding and minimizing noise factors that significantly influence timing performance of such detectors is vital. Currently, state-ofthe-art ToF-PET detectors are SiPM-based scintillation detectors, which introduces SiPM-specific noise sources, such as cross-talk. Cross-talk can occur in three scenarios, namely direct, delayed and external cross-talk. While there have been technological developments to address direct and delayed cross-talk, external cross-talk remains challenging to study because it is often mixed with the signal and other noise sources. This work aims to deepen our understanding of external cross-talk by measuring its probability and time distribution across different detector configurations. For this purpose, we conduct dark count measurements with high frequency electronics and an oscilloscope for readout. We investigate two Broadcom NUV-MT SiPMs one with 2 × 2 mm 2 and one with 3.8 × 3.8 mm 2 active area and couple each to three BGO crystals of different length (3 mm, 15 mm and 20 mm) wrapped in Teflon. Additionally, we test the SiPM without coupling, with direct Teflon ™ wrapping and coupled with the 3 mm crystal without wrapping. Our findings indicate that adding a reflector significantly increases cross-talk in scintillation detectors. The cross-talk probability increases from 1.9-fold to 1.4-fold with the lower end of this range corresponding to the coupling with the longest crystal (20 mm). Our setup successfully resolved the shift in cross-talk arrival time for crystals 15 mm and longer. Additionally, we have found that the minimal delay time for a 15 mm and 20 mm crystal corresponds to passing through the crystal twice and that changes in signal slope only occur after this delay time. This behavior is expected for any crystal size in a few-photon measurement.
Keywords: SiPM, Cross-talk, scintillator, TOF, BGO, PET, Optical
Received: 31 Mar 2025; Accepted: 16 Jun 2025.
Copyright: © 2025 Herweg, Schulz and Gundacker. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Katrin Herweg, Institute of Imaging and Computer Vision, RWTH Aachen University, Aachen, Germany
Stefan Gundacker, University Hospital RWTH Aachen, Aachen, 52074, Germany
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