Time resolution performance of an electro-optical-coupled PET detector for time-of-flight PET/MRI

Combining PET with MRI in a single system provides clinicians with complementary anatomical and molecular information. However, current combined PET/MRI systems do not have time-of-flight (ToF)-PET capabilities due to certain design choices. We have developed an MRI-compatible front-end electronic system with fast timing PET capabilities. Our approach employs, a fast arrival time pickoff comparator to digitize the timing information, and a laser diode to drive a fiber-optic cable to optically transmit timing information. The comparator and electo-optical link show 17ps +/- 0.2ps fwhm jitter in response to a fast digital pulse. When coupled with LSO scintillation crystals and Hamamatsu MPPC silicon photo-multipliers (SiPM) the comparator and electro-optical link achieved a time resolution of 265ps +/- 6.3ps with 3×3×20mm crystals and 167 +/- 3.6ps fwhm with 3×3×5mm crystals.