Insights and simulation of metascintillator-based brain PET systems to enhance ToF capability

Abstract

The integration of Time-of-Flight (ToF) information into Positron Emission Tomography (PET) image reconstruction enhances both signal-to-noise ratio and the localization of annihilation events. A critical component contributing to the accuracy of ToF-PET is the scintillator. To overcome the time resolution limitations in conventional scintillators, the metascintillator approach has been proposed. The metascintillator is an engineered composition of small units that combines and optimizes various features within a single scintillator heterostructure. In this work, metascintillator-based brain PET systems were simulated using the GATE toolkit and compared with designs based on bulk LYSO or BGO. Sensitivity, noise equivalent count rate (NECR) and scatter fraction were evaluated following NEMA guidelines. To match the peak sensitivity of a system utilizing a 15 mm bulk BGO, the metascintillator-based scanners using BGO/BaF2, BGO/EJ232, LYSO/BaF2 and LYSO/EJ232 must possess thicknesses of 23.2 mm, 22.5 mm, 29.7 mm and 31.1 mm, respectively. With ToF gain, the scanner utilizing a 25 mm thick LYSO-EJ232 metascintillator exhibited the most promising NECR curve, peaking at 1180 cps at 1600 MBq. This work takes a significant step towards harnessing the information gain facilitated by the integration of metascintillator-based detectors in PET imaging.