Prototype time-of-flight PET utilizing capacitive multiplexing readout method

Abstract

Positron emission tomography (PET) is an imaging technique that provides the spatial distribution of radiopharmaceuticals labeled with positron emitting radioisotopes by detecting the gamma rays produced from positron–electron annihilation. Recently, a time-of-flight (TOF) PET has drawn an increasing attention because it is capable of reducing the scan time or injected dose with improved the signal-to-noise ratio (SNR) in reconstructed PET images by precisely localizing the emission point along the line-of-response using TOF information.This study presents a multiplexing method that can effectively reduce the number of readout channels of a silicon photomultiplier (SiPM) based TOF PET while achieving excellent timing resolution. A capacitive multiplexing method was employed that could improve the degradation of the timing performance occurring in a conventional resistive multiplexing method. In addition, a high-speed signal processing method is also presented for the TOF PET. A TOF PET prototype was developed to demonstrate the imaging capability of the TOF PET system.A flood histogram of a PET detector module, composed of an 8×8 array of 3.01×3.01×20.00 mm3 lutetium fine silicate (LFS) scintillators and an 8×8 array of 3.16×3.16 mm2 SiPMs, was acquired using the proposed method. All 64 scintillators were successfully resolved in the flood histogram. The average energy resolution and coincidence resolving time (CRT) were 14.2 ± 1.1% and 431 ± 41 ps full width at half maximum (FWHM), respectively. A tomographic image of the hot-rod phantom was successfully acquired using the TOF PET prototype, and rods with a size of 2.4 mm in diameter were clearly resolved in the reconstructed image.