ADVANCES IN POSITRON TOMOGRAPHY FOR ONCOLOGY

Development of PET instrumentation over the past 42 years has moved fr om simple dual-detector coincidence scanners, to proposed systems havi ng 60,000 detectors and simultaneous coverage of 15-cm regions of the body with spatial resolutions better than 4 mm. The principal determin ants of positron emission tomography (PET) instrumentation advances ar e positron range, noncollinearity of the annihilation photons, scatter ing, random event rates, detector size, efficiency, speed and light ou tput; capability to correct for depth of crystal interaction, attenuat ion compensation, axial coverage, and rapid data analysis and presenta tion. While general-purpose systems with 2-mm resolution are expected, special purpose PET devices are being built for breast and brain tumo r studies with resolutions from 1.7 to 5 mm.