SBIR-STTR Award

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.

Thesaurus Terms:
biomedical equipment, biomedical equipment development, fluoride ion, particle accelerator, positron emission tomography heat, mechanical pressure, nonblood rheology, proton beam, thermometry, water flow bioimaging /biomedical imaging

The overall objective of the proposed work is to reduce the cost of accelerator produced F-18 radiopharmaceuticals used in Positron Emission Tomography (PET), a Medicare-reimbursed nuclear medicine metabolic imaging modality used to diagnose, stage, and restage ten cancer indications. Annual PET scans (350,000+) are rapidly increasing, but CMS reimbursement for PET scans is decreasing 23% from $1774 in 2004 to $1371 in 2005. Twenty percent of the total cost is the radiopharmaceutical dose of F-18 fluorodeoxy glucose (FDG). Sustaining growth in the use of PET will thus benefit from reducing the cost of producing FDG. The goal of this project is to lower cost per dose by a factor of 4-10 through use of a novel target invention accomplishing very high beam heat removal rates. Removing more heat allows use of high proton beam currents to produce the nuclear reaction O-18(p,n)F-18 to make F-18 fluoride ion for synthesis of FDG. Two commercial cyclotron manufacturers (Ion Beam Applications and Advanced Cyclotron Systems) use external injection ion sources that permit external beam currents of 300-500 microarnps, and thus beam power of 9-15 kilowatts. Current technology F-18 production targets capable of removing only about one kilowatt of heat, cannot take advantage of these high performance accelerators. Phase I experiments at Duke University utilized our patented miniature regenerative turbine pump and novel heat exchanger to achieve rapid recirculation at low target water pressures through a cyclotron target, establishing the feasibility of removing well above three kilowatts of heat if higher pressures are used. A cyclotron which will produce beam power of nine kilowatts has been identified for Phase n testing. Aim 1 is installing the Phase I target system on this accelerator, and operating at higher pressures to determine the thermal limit. Aim 2 is correlating these results with predictive thermohydraulic models for designing improved prototypes. Aim 3 is developing an optimum heat exchanger. Aim 4 is designing an optimized regenerative turbine pump with magnetic drive. Aim 5 is developing effective methods of recovering F-18 by sidestream extraction and/or batch methods. Aim 6 is to apply results from previous aims to design, build and test improved prototypes combining target, regenerative turbine pump, and heat exchanger in one compact assembly. Aim 7 is the design and demonstration of a reliable high-performance system suitable for widespread use. Aim 7 is thermohydraulic modeling to determine performance envelopes. The goal of Phase 3 is to make this technology available to appropriate commercial accelerators, thus implementing the overall goal of lowering the cost of PET scans by up to 15% by sienificantlv reducing the cost of oroducine FDG and other F-18 labeled radiooharmaceuticals