Novel inter-crystal scattering event identification method for PET detectors.

Area of Science:

• Medical Physics
• Instrumentation
• Nuclear Science

Background:

• Inter-crystal scattering (ICS) events pose a challenge in Positron Emission Tomography (PET) detector performance.
• Accurate identification and recovery of ICS events are crucial for improving PET image quality and quantitative accuracy.
• Existing methods may have limitations in handling complex detector designs like light-sharing configurations.

Purpose of the Study:

• To propose and validate a novel method for identifying inter-crystal scattering (ICS) events in PET detectors.
• To assess the applicability of the proposed method to both one-to-one coupling and light-sharing detector designs.
• To evaluate the impact of ICS event identification and recovery on intrinsic spatial resolution and energy linearity.

Main Methods:

• A linear problem formulation was used to model detector observations for ICS event identification.
• Two ICS identification techniques were explored: pseudoinverse matrix calculation and convex constrained optimization.
• Simulations with varying crystal array configurations and experimental studies using digital silicon photomultipliers and LGSO crystals were conducted.

Main Results:

• The convex optimization method achieved high ICS identification rates (0.93 for one-to-one, 0.87 for light-sharing).
• Energy estimation was robust with the convex optimization approach.
• Experimental validation demonstrated improved intrinsic spatial resolution after ICS recovery, reducing FWHM from 1.95mm to 1.72mm (one-to-one) and 2.25mm to 1.83mm (light-sharing).

Conclusions:

• The proposed method effectively identifies ICS events in both one-to-one and light-sharing PET detectors.
• Experimental results confirm that ICS recovery significantly improves intrinsic spatial resolution.
• This advancement holds promise for enhancing the accuracy and performance of PET imaging systems.