Positron Emission Tomography (PET) is a metabolic imaging modality used to diagnosis/stage/restage seven Medicare-reimbursed cancer types. Ninety six cyclotrons in US hospitals and distribution centers currently bombard stable enriched O-18 water targets with protons to produce F-18 fluoride ion for synthesis of F-18 fluorodeoxyglucose (FDG) used in 350,000 PET scans per year. CTI, EBCO, GE, and IBA market cyclotrons in the 10-20 Mev range, and their engineers are constantly improving ion sources and extraction to increase available beam. EBCO advertises 200 microamps of protons on target at 19 MeV (3.8 kW). IBA is working on """"""""self-extraction"""""""" in the mA range. We seek to demonstrate feasibility of our regenerative turbine (RT) recirculating target invention to accommodate beam power above 2 kW, allowing FDG production to more than triple. The heart of our system is a low-volume (about 2 cc) miniature regenerative turbine, which pumps liters per minute of high-pressure target water through the target and a low-volume heat exchanger. Transit time through the target beam strike is less than a millisecond, allowing target water to absorb several kW of heat while exiting before reaching the boiling point.
Aim 1 is to build and mechanically test a new Ag turbine pump, which is designed with a cantilevered pump shaft fitted with a water-lubricated ceramic bearing, and a seal capable of operating at 5000 rpm and 500 psig. Successful performance criteria will be the ability to recirculate 500psig water at 2 I/m with a pressure rise of 30 psig.
Aim 2 is to construct and test a miniature heat exchanger cooled with secondary water at the temperature and pressure of the cyclotron DI system. It will be fed with a 2 I/m source of 430F water at 500 psig (simulating the output of a target) produced by flowing water through an annulus surrounding a 2 Kw tubular electric heating element. Successful performance will be removing 2 kW of heat with an exit temperature of less 100F.
Aim 3 will be the connection of the pump and heat exchanger to a t cc silver target body for beam tests. Successful criteria will be achieving steady operation at 40 microamps of 27 MeV protons (1.04 kW) using natural water. Phase II will address F-18 yield experiments using O-18 target water, designing the target/heat exchanger/pump into a compact integral assembly to reduce pressure drops and total volume, and beta testing prototype integral systems at accelerators capable of greater than 2 kW beam power.
