Lawrence Berkeley National Laboratory

We present a conceptual design of a compact positron tomograph for prostate imaging using a pair of external curved detector banks, one placed above and one below the patient. The lower detector bank is fixed below the patient bed, and the top bank adjusts vertically for maximum sensitivity and patient access. Each bank is composed of 40 conventional block detectors, forming two arcs (44 cm minor, 60 cm major axis) that are tilted to minimize attenuation and positioned as close as possible to the patient to improve sensitivity. The individual detectors are angled to point towards the prostate to minimize resolution degradation in that region. Inter-plane septa extend 5 cm beyond the scintillator crystals to reduce random and scatter backgrounds. A patient is not fully encircled by detector rings in order to minimize cost, causing incomplete sampling due to the side gaps. Monte Carlo simulation (including randoms and scatter) demonstrates the feasibility of detecting a spherical tumor of 2.5 cm diameter with a tumor to background ratio of 2:1, utilizing the number of events that should be achievable with a 6-minute scan after a 10 mCi injection (e.g., carbon-11 choline or fluorine-18 fluorocholine).