Large Area Targetry Development for Continuous Production of Radioactive Gaseous Precursor of Astatine-211

The Department of Energy is seeking the development of alpha-emitters such as Astatine-211 (211At) that have been specifically identified as high priority isotopes in the report of the Nuclear Science Advisory Committee on Isotopes for targeted radiotherapy. Currently, only a few university facilities in the United States produce 211At, which requires alpha beam irradiation of a low melting bismuth target. With a half-life of 7.2 hours, 211At use is limited to facilities in close proximity to the source. Delivery of Radon-211 (211Rn, half-life 14.6 hours), a generator of 211At, could mitigate this situation for its on-site availability in medical facilities distant from the cyclotron production centers. Following a proof of concept demonstration, the team will further develop a large area, non- sintering nanoporous bismuth oxide target for irradiation with lithium beams. This will enable an efficient and on-line, on-demand route for the continuous extraction of 211Rn, a gaseous generator for 211At. It is conjectured that the interconnected pores in the target enable Helium carrier gas-enabled diffusion of 211Rn to be trapped in a charcoal trap. This simplifies the production route for 211Rn and enables the reach of 211At to many more treatment centers in the nation. The emphasis of this work will be to improve targetry for the production of 211Rn using lithium beam irradiation. In Phase I, the small business will further the development of large area nanoporous, bismuth oxide films on metallic backing for lithium beam irradiation studies by the subcontractor. The bismuth oxide films will be prescreened for robustness to thermal cycling between room temperature and 700 °C in inert gas environments. Target films will be characterized for retention of the interconnected porous structure, crystallographic phase and composition, and adhesion to the backing plate. Prescreened targets will be evaluated by the subcontractor at the beamline facility, by implanting higher current intensity Lithium-6 beams to characterize the target lifetime and product (211Rn) yield. The non-sintering nanoporous bismuth oxide films will extend the accessibility of 211At for radiotherapy to user facilities that are far from the existing university production facilities in the United States. There are 36 cyclotrons in the world with the capability to produce 211At. However, it is not being pursued because of the lack of specific expertise in 211At production or a demand for the short-lived isotope. The Global Radiopharmaceuticals Market is expected to reach $9.25B by 2025 a Compound Annual Growth Rate (CAGR) of 8.6% from 2018 to 2025. Hospitals are the largest end users