Estimation of crystal timings in TOF-PET

In this work, we propose a method to compute TOF resolutions from TOF-PET emission data using a crystal model. For each line of response, the TOF resolutions were computed as the hypotenuse of crystal timing resolutions of the crystals in coincidence. We find that the accuracy of the crystal timing resolutions highly depends on the average count per crystal. In the phantom study, we observe a small global shift in the TOF-resolution, which we believe to be due to the scans being performed at different count rates. However, the whole body patient study shows that the count rate possibly is not the only factor influencing the crystal timing properties. The effect of the TOF resolution on joint reconstructions (and more so on standard reconstructions) seems to be limited as long as the mean crystal TOF resolution is modelled during reconstruction.