Abstract
Developing time-of-flight positron emission tomography/magnetic resonance imaging (TOF-PET/MRI) detectors that exploit prompt Cherenkov photons from bismuth germanate (BGO) crystals for estimating 511keV photon arrival time. To present a low-noise, high-speed electronic readout circuit design for BGO-based TOF-PET detectors that achieves enhanced coincidence time resolution (CTR) in presence of a strong magnetic field. The CTR of a BGO-based TOF-PET test detector employing a high-speed, low-noise electronic readout chain was evaluated in a strong magnetic field produced by a permanent magnet placed directly on top of the circuit. For these experiments, which exploit Cherenkov radiation for precise measurement of annihilation photon time arrival time difference, a point source of 22Na was positioned between a pair of 3×3×15mm3 polished BGO crystals wrapped in Teflon tape and optically coupled to 3×3mm2 ultra-violet (UV)-sensitive silicon photomultipliers (SiPMs). By incorporating both Cherenkov (prompt) and standard (slow) luminescence components, 283±8ps and 275±10ps full-width-half-maximum(FWHM) CTR were achieved without and with the permanent magnet present, respectfully. These values improved to 236±4ps and 216±17ps FWHM when only the Cherenkov components of the timing signal (events with the fastest rise time) were considered. Results indicate we have designed a high-performance readout circuit that achieves significantly the same CTR in BGO with or without a strong magnetic field present. This further demonstrates that UV SiPMs can effectively operate in a strong magnetic field while remaining highly advantageous for detecting Cherenkov radiation, thus highlighting their potential to be used in BGO-based TOF-PET/MRI scanners.
Published Version
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