Improving CTR with the FastIC ASIC for TOF-PET by overcoming SiPM noise with baseline correction

Area of Science:

• Medical Imaging
• Nuclear Physics
• Detector Technology

Background:

• Time-of-flight positron emission tomography (TOF-PET) has seen significant timing resolution improvements.
• Silicon photomultipliers (SiPMs) are crucial for TOF-PET but introduce noise when operated at high bias voltages.
• SiPM noise causes baseline fluctuations and time-walk, limiting timing performance in TOF-PET systems.

Purpose of the Study:

• To investigate the impact of SiPM baseline fluctuations on TOF-PET timing performance.
• To develop and evaluate a scalable method for flagging noisy events in TOF-PET detectors.
• To assess the effectiveness of different classification and correction techniques for SiPM noise.

Main Methods:

• Utilized the FastIC ASIC, a scalable multichannel readout, to examine SiPM baseline fluctuations.
• Implemented a comparator signal triggered by dark counts to flag noisy events before scintillation.
• Tested classification and correction methods with BGO, LYSO crystals, and EJ232 plastic scintillators coupled to analog SiPMs.

Main Results:

• Correcting time-walk on noisy events reduced coincidence time resolution (CTR) in BGO crystals by 5% (410 ps to 388 ps).
• Filtering noisy events improved CTR by 11% for LYSO crystals (107 ps to 93.5 ps).
• An improvement of 9% in CTR was achieved for EJ232 plastic scintillator (82.2 ps to 75 ps).

Conclusions:

• A scalable method for flagging undesired SiPM events in TOF-PET systems was successfully developed.
• The developed method effectively mitigates SiPM noise, leading to significant improvements in coincidence time resolution.
• This work highlights the impact of SiPM noise on fast timing applications and offers a practical solution for TOF-PET detectors.