Cerenkov light transport in scintillation crystals explained: Realistic simulation with GATE

Emilie Roncali, Sun Il Kwon, Sebastien Jan, Eric Berg, Simon R Cherry

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Purpose: We are investigating the use of promptly emitted Cerenkov photons to improve scintillation detector timing resolution for time-of-flight (TOF) positron emission tomography (PET). Bismuth germanate (BGO) scintillator was used in most commercial PET scanners until the emergence of lutetium oxyorthosilicate, which allowed for TOF PET by triggering on the fast and bright scintillation signal. Yet BGO is also a candidate to generate fast timing triggers based on Cerenkov light produced in the first few picoseconds following a gamma interaction. Triggering on the Cerenkov light produces excellent timing resolution in BGO but is complicated by the very low number of photons produced. A better understanding of the transport and collection of Cerenkov photons is needed to optimize their use for effective triggering of the detectors. Methods: We simultaneously generated and tracked Cerenkov and scintillation photons with a new model of light transport that we have released in GATE V8.0. This crystal reflectance model was used to study photon detection and timing properties, building realistic waveforms as measured with silicon photomultipliers. Results: We compared the behavior and effect of detecting Cerenkov and scintillation photons at several levels, including detection time stamps, travel time, and coincidence resolving time in 3 ×3 ×20 mm 3 BGO crystals. Simulations showed excellent agreement with experimental results and indicated that Cerenkov photons constitute the majority of the signal rising edge. They are therefore critical to provide early triggering and improved the coincidence timing resolution by 50%. Potential applications: To our knowledge, this is the first complete simulation of the generation, transport, and detection of the combination of Cerenkov and scintillation photons for TOF detectors. This simulation framework will allow for quantitative study of the factors influencing timing resolution, including the photodetector characteristics, and ultimately aid the development of BGO and other Cerenkov-based detectors for TOF PET.

Original languageEnglish (US)
Article number035033
JournalBiomedical Physics and Engineering Express
Volume5
Issue number3
DOIs
StatePublished - Apr 17 2019

Keywords

  • Cerenkov
  • Monte Carlo simulation
  • positron emission tomography
  • radiation detector
  • timing resolution

ASJC Scopus subject areas

  • Nursing(all)

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