Performance evaluation of the next generation solid-state digital photon counting PET/CT system

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Physics

Background:

• Introduction of the first solid-state digital photon counting (DPC) clinical PET/CT system by Philips.
• This system utilizes lutetiumyttrium oxyorthosilicate (LYSO) scintillators directly coupled with individual SiPM DPC detectors, eliminating the need for Anger-logic positioning.
• Evaluation of a next-generation DPC clinical PET/CT system.

Purpose of the Study:

• To evaluate the system performance, characteristics, and stability of the new DPC clinical PET/CT system.
• To compare its capabilities against conventional systems using established NEMA standards.
• To assess its potential for clinical applications.

Main Methods:

• Performance evaluation using NEMA NU2-2012 and NEMA NU2-2018 (timing resolution) standards.
• Assessment of spatial resolution, sensitivity, noise equivalent count rate (NECR), scatter fraction, and count rate performance.
• Evaluation of hot and cold sphere contrast, timing resolution, energy resolution stability, and recovery coefficients.

Main Results:

• Measured energy resolution of 11.2% and spatial resolution ranging from 3.96 mm (axial) to 5.83 mm (tangential) at 20 cm depth.
• System sensitivity of 5.7 cps/kBq; peak NECR and true count rate increased up to 1100 MBq.
• Maximum NECR of 171 kcps, scatter fraction of 30.8%, and timing resolution of 322-332 ps.
• Excellent stability over 31 months with <1% change in TOF timing and ±0.4% change in energy resolution.
• High contrast recovery coefficients (60-100%) across various sphere sizes and contrast levels.

Conclusions:

• The solid-state DPC PET/CT represents a significant technological advancement over traditional photomultiplier tube (PMT) systems.
• The system demonstrates substantial improvements in performance, characteristics, and excellent time-of-flight (TOF) capability.
• This DPC system offers promising clinical opportunities with superior image quality, enhanced lesion detectability, and increased diagnostic confidence.