A fast and accurate timing alignment method with TDC linearity calibration for a high-resolution TOF-PET

An accurate PET system timing alignment minimizes the coincidence time-window for reducing random events and improves image quality; it also is critical for time-of-flight (TOF) image reconstruction. In this work, we proposed to use a thin cylindrical ring (shell) phantom filled with radioactive source and located axially and centrally in a camera for the alignment of a high time-resolution TOF PET system. The timing alignment method involves measuring the time differences between the selected coincidence detector pairs, calibrating the differential and integral non-linearity of TDC with the same raw data, and deriving the intrinsic timing biases for each detector using an iterative algorithm. The raw time bias for each crystal will be downloaded to the front-end EPROM and the residual fine bias can be applied to the TOF list-mode reconstruction.