An optically coupled hybrid semi-monolithic PET detector for simplified DOI and position decoding

Area of Science:

• Medical Imaging Physics
• Detector Technology
• Nuclear Medicine

Background:

• High-performance detectors are crucial for long axial field-of-view (FOV) clinical PET systems.
• Encoding depth-of-interaction (DOI) is essential for improved PET imaging.
• Existing designs often face challenges in balancing DOI capability with timing and energy resolution.

Purpose of the Study:

• To propose and evaluate a novel optically coupled hybrid semi-monolithic detector design for PET systems.
• To enable DOI capability while maintaining high timing and energy resolution.
• To simplify positioning calibration for clinical PET applications.

Main Methods:

• Fabrication of a prototype detector using a pixelated lutetium-yttrium oxyorthosilicate (LYSO) array coupled to a monolithic LYSO slab via optical adhesive.
• Utilizing a high-refractive-index adhesive (n=1.7) for optical coupling.
• Employing a TOFPET2 application-specific integrated circuit (ASIC) for detector readout.

Main Results:

• Achieved an average DOI resolution of 4.0 ± 0.5 mm.
• Obtained an average energy resolution of 11.7% ± 0.9%.
• Demonstrated a coincidence timing resolution (CTR) of 281 ps with good spatial resolution.

Conclusions:

• The proposed hybrid detector design effectively balances detector performance (DOI, timing, energy resolution) with calibration complexity.
• This design presents a promising solution for next-generation long axial FOV clinical PET systems.
• The simplified calibration process enhances the practicality of advanced PET detector technology.