NEW TARGET TECHNOLOGY FOR PET RADIONUCLIDE PRODUCTION

THE OBJECTIVE OF THIS EFFORT IS TO DEVELOP NEW ION BEAM TARGET CHAMBER TECHNOLOGIES THAT WILL INCREASE RELIABILITY WHILE MAINTAINING HIGH YIELD CAPABILITY FOR THE PRODUCTION OF POSITRON EMISSION TOMOGRAPHY (PET) RADIOISOTOPES (O-15, N-13, C-11, F-18) OBTAINED WITH THE NEW LOWER COST, LOWER ENERGY (3-4 MEV) ACCELERATORS NOW BEING DEVELOPED FOR PET. SINCE TARGET FOIL FAILURE IS A LIMITING FACTOR IN THE PERFORMANCE OF EXISTING CYCLOTRON-BASED PET RADIOPHARMACEUTICAL SYSTEMS, THE RESULTS OF THE PROGRAM WILL ALSO BE VALUABLE IN IMPROVING THE PERFORMANCE OF CURRENT PET SYSTEMS. THE NEW ACCELERATORS MUST OPERATE AT HIGHER CURRENTS (UP TO 1 MA VERSUS 50 MUA WITH HIGH ENERGY CYCLOTRONS) TO ACHIEVE THE 1-2 CURIE SATURATED YIELDS OF THESE RADIOISOTOPES REQUIRED FOR MEDICAL IMAGING APPLICATIONS. THESE HIGH CURRENTS, IN TURN, REQUIRE A FACTOR OF 40 TIMES MORE COOLING CAPACITY FOR THE ION BEAM TRANSMISSION WINDOW (FOIL) WHICH SEPARATES THE EVACUATED ACCELERATOR BEAM LINE FROM THE TARGET CHAMBER. THE NEW TARGET CHAMBER TECHNOLOGIES INCLUDE (1) CONDUCTION-COOLED FOILS AND FOIL SUPPORT STRUCTURES WITH A HIGH-ASPECT-RATIO GEOMETRY, (2) NEW METHODS OF MOUNTING THESE FOILS TO REDUCE STRESS AND EXTEND FOIL LIFE, AND (3) A NOVEL CRYOGENIC O-18 ICE TARGET FOR THE PRODUCTION OF F-18.