On timing-optimized SiPMs for Cherenkov detection to boost low cost time-of-flight PET

Area of Science:

• Nuclear Instrumentation and Medical Imaging
• Particle Detectors and Photodetectors

Background:

• Silicon photomultiplier (SiPM) developments and improved front-end electronics are crucial for time-of-flight positron emission tomography (TOF-PET).
• Bismuth-germanate (BGO) crystals offer high Cherenkov yield and cost-effectiveness for total-body PET scanners, but require optimized electronic readout and timing.
• Previous lab experiments showed promising coincidence time resolution (CTR) with small SiPM pixels but suffered from high power consumption.

Purpose of the Study:

• To implement practical, low-power (<30 mW) circuits for SiPMs and test their CTR performance with BGO crystals.
• To evaluate newly developed SiPMs from Fondazione Bruno Kessler optimized for single photon time resolution (SPTR).
• To demonstrate the potential of Cherenkov detection in BGO for advanced TOF-PET systems.

Main Methods:

• Implemented low-power (<30 mW) front-end electronics for SiPMs.
• Tested CTR performance using BGO crystals (2x2x3 mm³ and 3x3x20 mm³) and commercially available LYSO:Ce,Mg crystals (3x3x20 mm³).
• Measured SPTR using black-coated PbF₂ crystals (2x2x3 mm³) and 1x1 mm² SiPMs to characterize timing properties.

Main Results:

• Achieved best CTR FWHM of 123 ps with 2x2x3 mm³ BGO and 243 ps with 3x3x20 mm³ BGO crystals.
• Demonstrated a CTR of 106 ps using 3x3x20 mm³ LYSO:Ce,Mg crystals.
• Confirmed improved SPTR from 68 ps (standard SiPMs) to 42 ps (optimized SiPMs) and achieved 28 ps with 1x1 mm² devices.

Conclusions:

• Advancements in SiPMs and readout electronics significantly improve CTR with Cherenkov-emitting crystals.
• Enabling TOF-PET with BGO crystals offers a pathway to low-cost, high-performance total-body scanners.
• Future CTR improvements are feasible with prompt Cherenkov emission, necessitating continued development of low-power electronics.