A Time-Walk and Timing-Shift Correction Method for Dual-Ended Readout TOF-DOI PET Detectors

Abstract

Positron emission tomography (PET) detectors suffer from time-walk when the leading edge discriminator is employed for timing pick-off as well as a timing-shift when thick crystals are utilized due to the depth-of-interaction (DOI) effect. In this study, a combined time-walk and timing-shift correction method was proposed for dual-ended readout PET detectors. To evaluate the proposed method, a pair of dual-ended readout PET detectors was constructed. Each detector was based on two Hamamatsu S14161-3050-08 silicon photomultiplier (SiPM) arrays coupled to both ends of an $8\times 8$ arrays of $3.1\times 3.1\times 20~{\mathrm { mm}}^{3}$ lutetium-yttrium oxyorthosilicate crystals with a 3.2-mm pitch. By employing the relationship between the energies and detected time differences of events, the time-walk and timing-shift were effectively corrected. The coincidence time resolution of the two detectors improved from $260.7~\pm ~1.0$ ps to $229.4~\pm ~1.0$ ps when a 400–650 keV energy window was used to select events. These results demonstrate the effectiveness of the proposed time-walk and timing-shift correction method.