Self-thresholding, 48:2 multiplexed readout circuit for a 3D position sensitive, 100 ps CTR TOF-PET detector

Area of Science:

• Medical Imaging Physics
• Nuclear Instrumentation
• Positron Emission Tomography (PET)

Background:

• Precise three-dimensional (3D) position resolution is critical for advancing time-of-flight positron emission tomography (TOF-PET) detector performance.
• Existing TOF-PET systems often face challenges with system complexity, size, power consumption, and cost, limiting their widespread application.
• Achieving sub-2 mm depth of interaction (DOI) resolution and ~100 picosecond (ps) coincidence time resolution (CTR) is a key goal for next-generation PET scanners.

Purpose of the Study:

• To develop and validate a compact, low-power 3D position-sensitive scintillator readout circuit for TOF-PET detectors.
• To enable precise DOI resolution and maintain high CTR performance using a novel charge-division scheme.
• To reduce system complexity, footprint, power consumption, and cost compared to existing TOF-PET readout architectures.

Main Methods:

• Implemented a low-power, anger-based charge-division circuit with on-board real-time X/Y processing for 3D position-sensitive readout.
• Integrated custom low-noise, low-power front-end electronics featuring independently self-thresholding 48:2 multiplexed timing and energy/3D positioning circuits.
• Utilized 3x3x10 mm³ LGSO crystal elements coupled to silicon photomultipliers (SiPMs) for experimental validation of the detector design.

Main Results:

• Achieved continuous DOI resolution of approximately 1.6 ± 0.3 mm FWHM.
• Demonstrated an average CTR of 102.5 ± 2.7 ps FWHM across a range of SiPM bias voltages, with <5 ps FWHM variation.
• Obtained energy resolutions of 18% FWHM (TOT) and 13% FWHM (dynamic TOT) at 511 keV, with event detection down to 31 keV.

Conclusions:

• The developed 3D position-sensitive scintillator readout circuit effectively enables precise DOI resolution and maintains high CTR performance in TOF-PET detectors.
• The system achieves significant reductions (≥40%) in component count, footprint, power consumption, and cost compared to previous designs.
• This compact and efficient readout design offers a promising solution for next-generation, high-performance TOF-PET systems.