Enhanced MVT digitizer in PET

We have explored, and continue exploring the potentials of the multi-voltage threshold (MVT) method that we previously proposed. By using of this method, we digitize PET event pulses by taking timing samples with respect to a number of predefined thresholds. Previous studies indicate that the MVT method is capable of obtaining sufficient accurate timing information for developing time-of-flight (TOF) PET. In previous studies, we observed that noise always influences sampling accuracies at a pulse decay tail. In this work, we develop an enhanced MVT digitizer (EMVTD). By obtaining both of the first timing sample and the last one in the timing sample sequence of a decay tail, the EMVTD is able to retrieve more accurate timing samples at the pulse decay tail. We describe the design and an initial implementation of this digitizer and report its performance properties. We also investigate the feasibility of capturing all the samples with respect to every threshold that we predefined to improve the accuracy of pulse shape reconstruction. The EMVTD offers an intrinsic timing resolution of 150ps FWHM and an energy resolution of 17.5%@662keV. In addition, preliminary results show the potentials of energy resolution improvement with the current implementation of EMVTD.