Optical Simulation and Experimental Assessment with Time-Walk Correction of TOF-PET Detectors with Multi-Ended Readouts.

Siwei Xie,Hongsen Yu,Qiyu Peng,Jianfeng Xu,Qiangqiang Xie,Yibin Zhang,Zhiliang Zhu,Xi Zhang

doi:10.3390/s21144681

Abstract

As a commonly used solution, the multi-ended readout can measure the depth-of-interaction (DOI) for positron emission tomography (PET) detectors. In the present study, the effects of the multi-ended readout design were investigated using the leading-edge discriminator (LED) triggers on the timing performance of time-of-flight (TOF) PET detectors. At the very first, the photon transmission model of the four detectors, namely, single-ended readout, dual-ended readout, side dual-ended readout, and triple-ended readout, was established in Tracepro. The optical simulation revealed that the light output of the multi-ended readout was higher. Meanwhile, the readout circuit could be triggered earlier. Especially, in the triple-ended readout, the light output at 0.5 ns was observed to be nearly twice that of the single-ended readout after the first scintillating photon was generated. Subsequently, a reference detector was applied to test the multi-ended readout detectors that were constructed from a 6 × 6 × 25 mm3 LYSO crystal. Each module is composed of a crystal coupled with multiple SiPMs. Accordingly, its timing performance was improved by approximately 10% after the compensation of fourth-order polynomial fitting. Finally, the compensated full-width-at-half-maximum (FWHM) coincidence timing resolutions (CTR) of the dual-ended readout, side dual-ended readout, and triple-ended readout were 216.9 ps, 231.0 ps, and 203.6 ps, respectively.

Highlights

The effective axial length of current human Positron emission tomography (PET)systems is generally 25 cm to 35 cm, resulting in a number of effective events that are unable to be detected [1,2]
After multiple reflections on the internal surfaces of the scintillator, the photons are generated as a result of photoelectric or Compton interactions between the 511 keV gamma and the scintillator and detected by silicon photomultiplier (SiPM) with a reaction area of 6 × 6 mm2
For a traditional single-ended readout, half of the photons fly toward the SiPM while the Sensors 2021, 21, 4681 describe the surface characteristics of optical materials including absorption, reflection, transmission, and scattering [34]

Summary

Introduction

The effective axial length of current human Positron emission tomography (PET). Systems is generally 25 cm to 35 cm, resulting in a number of effective events that are unable to be detected [1,2]. The system’s sensitivity and image signal-to-noise (STN). Increasing the axial length is an effective method in improving its sensitivity. F. Budinger in 1977 [3], where positron annihilation positions were calculated by measuring the triggering time difference of two gamma photons. By improving the timing performance of the detector while reducing the uncertainty of positron annihilation localization, the sensitivity of the PET system may be effectively improved [4,5,6,7]

Methods

Results

Conclusion