Depth of Interaction and Coincidence Time Resolution Characterization of Ultrahigh Resolution Time-of-Flight Prism-PET Modules

Depth-of-interaction (DOI) positron emission tomography (PET) detector with time-of-flight (TOF) readout has been developed in recent years. With DOI, PET scanner could achieve high spatial resolution and high sensitivity simultaneously. With improved TOF readout, better coincidence time resolution (CTR) is achieved, making the localization of events along the lines of response (LORs) more accurate and enhancing the reconstructed image quality. Prism-PET is a novel DOI-TOF PET detector module with single-ended readout. It utilizes segmented prismatoid light guide array for enhanced and localized light sharing and aims to solve the tradeoff among spatial resolution, sensitivity, and cost. In this work, we characterized the DOI resolution and CTR performance of our Prism-PET module. Unprecedented DOI resolutions of 2.57 mm full width at half maximum (FWHM) and 4.01 mm FWHM were achieved in our 4-to-1 and 9-to-1 crystal-to-pixel coupled Prism-PET modules, respectively, outperforming that of a 4-to-1 PET module with a uniform glass light guide (5.72 mm FWHM). Estimated time resolutions (FWHM) after DOI correction were 254 ps and 267 ps for the 4-to-1 and 9-to-1 Prism-PET modules, respectively.