A novel time to digital converter architecture for time of flight positron emission tomography

Positron emission tomography (PET) is a molecular imaging technique that provides images of physiological processes inside the body. In clinical applications, PET image quality benefits from the time of flight (TOF) feature. This is based on measuring the difference in the arrival times of couples of nearly collinear photons generated during the PET exam on a detector ring with a resolution less than 100 ps. In this scenario, a time to digital converter (TDC) can be used for the read out of the detectors to provide the photon arrival time. If matrices of Silicon Photomultipliers are used as photodetectors, multichannel topology and real time noise rejection capability are strongly required in the design of the converter along with good linearity. We present an innovative TDC architecture which is suitable for TOF PET applications.