I. Introduction
Time-of-flight (TOF) PET makes use of very fast gamma-ray detectors and timing measure system to precisely measure the difference between the arrival times of the two coincident gammas. The measurements of arrival signalings have several sources of errors that can lead to biases in TOF measurements, which degrades the imaging capability of a TOF PET scanner. These factors include differences in crystal scintillation behavior, variations in detector transit times, operating temperature, electronics delays caused by, e.g., signal trace length, pulse discrimination, and triggering. Therefore, timing calibration is critical to achieve the best possible timing resolution, and maximize the benefit of TOF PET scanners [1] In this work, we present an autonomous timing calibration for 3D TOF PET.