Gas targets for the production of 15O, 11C and 18F for pet studies*

Production of 15 O, 11 C and 18 F is achieved with particle irradiation of gaseous targets. Design features for generalized targets include characterization of window materials and cooling, target size and shape, beam size and profile, and chamber cooling and operating pressure. A cylindrical design is employed that utilizes a C-ring for sealing the target window to the target body. Ultrapure materials are required for fabrication of 11 C and 18 F targets. Use of welded joints are to be limited on all targets and climinated on 18 F systems. Tomographic techniques will be used to determine the cross-sectional temperature profile of target gases during bombardment. Mass species are measured with a sector focused mass spectrometer while the target undergoes particle irradiation for production of clinical agents. This diagnostic information is useful for tailoring the bomardment conditions to achieve optimal precursor production and the highest specific activity that may be obtained from the target.