Advancements in DOI-capable TOF-PET modules using a multi-channel high-frequency readout.

Area of Science:

• Medical Imaging
• Nuclear Physics
• Materials Science

Background:

• Improving signal-to-noise ratio and spatial resolution is key for time-of-flight positron emission tomography (TOF-PET).
• Mitigating the effect of gamma-ray depth of interaction (DOI) is essential for long scintillators in TOF-PET.
• High spatial resolution requires precise timing and accurate DOI information.

Purpose of the Study:

• To develop a DOI-capable module for TOF-PET that enhances timing resolution.
• To address the challenge of depth of interaction in long scintillators.
• To improve the overall image quality in TOF-PET.

Main Methods:

• Utilized a matrix of sixteen 20 mm-long LYSO:Ce scintillators with depolished lateral surfaces.
• Employed a light guide for intra-matrix light sharing to determine gamma-ray DOI and correct timing bias.
• Integrated a sixteen-channel, low-noise, high-frequency circuit board for multi-channel readout and enhanced time resolution.

Main Results:

• Achieved a DOI resolution of 2.2 ± 0.2 mm FWHM and a coincidence time resolution (CTR) of 133 ± 2 ps FWHM after DOI correction.
• The DOI-capable module demonstrated timing resolution comparable to a standard module (130 ± 2 ps FWHM).
• Successfully encoded DOI information with a resolution of nearly 2 mm FWHM.

Conclusions:

• The DOI-capable module, using 20 mm LYSO:Ce crystals and high-frequency electronics, provides excellent timing and energy resolution.
• This module achieves DOI encoding capability while maintaining timing resolution similar to standard TOF-PET modules.
• The developed technology offers significant potential for advancing TOF-PET imaging quality.