An accurate and robust time calibration method for PET with high DOI resolution

PET time alignment refers to the process of correcting the time differences between the signals detected by different detectors in a PET scanner. The arrival times of the signals detected by each detector may differ due to various factors such as differences in cable length, signal processing delays, and temperature variations. This can result in errors in the reconstruction of the PET image, reducing its spatial and temporal resolution. To address this, PET scanners incorporate time alignment techniques to synchronize the signals detected by different detectors.DOI (Depth-of-Interaction) PET refers to a type of positron emission tomography (PET) scanner that is designed to improve the spatial resolution of PET images by allowing for the detection of the depth of interaction of the gamma photons within the scintillator crystals. We have designed and made a DOI PET scanner. The position of the interaction along the depth axis is calculated based on the ratio of the light produced in the sensors. It is possible to regard each small DOI segment as a small crystal.Time alignment on DOI PET is similar to that on traditional PET scanners, but with some additional considerations due to the use of segmented scintillator crystals. One of the main challenges of doing time alignment on DOI PET is the increased complexity of the detector system due to the segmentation of the scintillator crystals. With traditional PET scanners, the signals from all the crystals in a module are combined to form a coincidence event, and any time offsets between the crystals can be easily corrected for using a single time offset value. However, with DOI PET, the signals from each crystal segment must be separately timed and combined, which requires more advanced timing algorithms and huge data. In this work, we extend the time alignment method and designed a method that does not need that huge data, and could output accurate time offsets result.