Positron Production and PET Scanning

A new program to study anatomical and physiological aspects of the brain that use positron emission tomographic (PET) techniques was instituted at the University of Michigan. A complete laboratory was constructed to facilitate the production of radiotracers, their incorporation into viable radiopharmaceuticals and the detection of their regional localization. The Cyclotron Corporation (TCC) CS-30 compact cyclotron is used to provide various short-lived ß + nuclides. Targets for C-11, N-13, O-15 and F-18 are accomodated on three external beam lines. Steady-state production of several simple physiological tracers are possible and include 15O2, H215O, C15O, 11CO, C15O2 and 11CO2. These gases are purified and available to the chemist in the laboratory or may be diverted to the clinical imaging area for direct inhalation. A F-18 labeled compound, 2-deoxy-2-fluoro-D-glucose (2FDG), is used for determining the level of brain metabolic activity and requires long irradiation/synthesis times. The incorporation of 18F2 into 2FDG is an involved process and has been automated to reduce radiation exposure to the chemist and enhance overall yields. Once the purity of the radiopharmaceuticals is verified it is then injected or inhaled by the patient. The TCC 4600A Neuro Positron Camera Tomograph is used to obtain transaxial images of the brain derived from the annihilation photons of the ß+ tracers. The scanner resolution is 1.0 cm by 1.0 cm within the slice and 1.0 cm between slices. The tomograph is capable of simultaneously acquiring 5 slices in 5 seconds at the maximum spatial resolution.