Purpose:To Time-of-Flight positron emission tomography(TOF-PET),the TOF benefit highly depends on the system timing precision.As a result,it is meaningful to measure the time resolution of the PET system.However,there is not any standard procedure for the measurement.In the article,we used the standard NEMA NECR and NEMA sensitivity coincidence data to analyze the PET system time resolution.Methods:The NECR measurement has many scatter events during the PET scanning.It is difficult to distinguish the real events and the scatters events.It is hard to evaluate the scatter events as well.Therefore,we proposed to use the coincidence data acquired from standard NEMA sensitivity measurement procedure.We used at least 10000 trues per slice collected from the sensitivity data acquired by the PET system.It is hard to ignore the statistics error on each Line-of-Response(LOR).It is necessary to merge the data of all five data sets acquired with different size absorbers.In practice,Inaccurate positioning of the line source in the center of PET FOV may lead to imprecise time resolution result.In order to compensate the time difference caused by misplacing,we introduced a source alignment procedure,which takes the advantage of the rigid line source.ResultsBy using the proposed method,we can get a global time resolution measurement.Conclusions:It is shown that,by using the sensitivity data acquired by standard NEMA procedure,we can get a measurement of the time resolution of the PET system.