Segmented readout for Cherenkov time-of-flight positron emission tomography detectors based on bismuth germanate

TL;DR

This paper presents a novel segmented readout method for Cherenkov-based PET detectors using bismuth germanate, improving timing resolution by classifying events through multiple time stamps and photon counts from segmented SiPMs.

Contribution

It introduces a segmentation approach for SiPMs coupled to BGO crystals, enabling better event classification and timing resolution in Cherenkov TOF PET detection.

Findings

Segmented SiPMs improve event classification accuracy.

Multiple time stamps enhance timing resolution.

Potential applications in medical imaging and physics.

Abstract

Positron emission tomography (PET) is the most sensitive biomedical imaging modality for non-invasively detecting and visualizing positron-emitting radiopharmaceuticals within a subject. In PET, measuring the time-of-flight (TOF) information for each pair of 511-keV annihilation photons improves effective sensitivity but requires high timing resolution. Hybrid materials that emit both scintillation and Cherenkov photons, such as bismuth germanate (BGO), recently offer the potential for more precise timing information from Cherenkov photons while maintaining adequate energy resolution from scintillation photons. However, a significant challenge in using such hybrid materials for TOF PET applications lies in the event-dependent timing spread caused by the mixed detection of Cherenkov and scintillation photons due to relatively lower production of Cherenkov photons. This study introduces an innovative approach by segmenting silicon photomultiplier (SiPM) pixels coupled to a single crystal, rather than using traditional SiPMs that are as large as or larger than the crystals they read. We demonstrated that multiple time stamps and photon counts obtained from the segmented SiPM can classify events by providing temporal photon density, effectively addressing this challenge. The approach and findings would lead to new opportunities in applications that require precise timing and photon counting, spanning the fields of medical imaging, high-energy physics, and optical physics.