OPTIMIZING ROD WINDOW WIDTH IN POSITRON EMISSION TOMOGRAPHY

A technique determines the optimal window width for orbiting rod trans mission studies in positron emission tomography (PET). Windowing reduc es noise in orbiting rod transmission studies, Lines-of-response (LOR) which intersect the rods generate primarily true coincidence events, LOR which pass far from the rods generate random and scatter events, S ince the angular position of the orbiting rods is known in real-time, LOR which produce mostly noise are gated off, When optimally determine d, the rod window width maximizes the noise equivalent counts (NEC) co llected in the transmission study, Transaxial rod projection profiles of trues, randoms, and scatter produce NEC versus window width plots, For the ECAT((R))EXACT line of PET systems and a 20-cm water cylinder, optimal is five LOR wide.