An experimental evaluation of the effect of time-of-flight information in image reconstructions for the Scanditronix/PETT Electronics SP-3000 positron emission tomograph-preliminary results

The effects of detector energy thresholds and time-of-flight information on image quality were investigated for the SP-3000 positron emission tomograph. Phantom studies were performed with different energy discriminator settings. A software preprocessor allowed images to be reconstructed from list mode data with different time-of-flight windows. In general, the inclusion of time-of-flight information in image reconstruction improved SNR (signal to-noise-ratio) over conventional filtered back-projection techniques. The data indicate that setting the energy discriminator level higher than the 170 keV currently used in the machine could be beneficial. The results demonstrated the need for good quality assurance testing for time-of-flight offsets and gains, and they indicate that the current look-ahead coincidence system may need to be modified