Los Alamos scientist F. Meiring Nortier, PhD, holds a thorium foil test target for the actinium 225 production experiments. Source: Los Alamos National Laboratory

A new medical isotope project at Los Alamos National Laboratory (LANL) in New Mexico, has shown promise for producing major quantities of a new cancer-treatment agent, actinium 225 (Ac-225).

Using proton beams, a collaboration between Los Alamos, Brookhaven and Oak Ridge national laboratories is developing a plan for full-scale production and stable supply of Ac-225, which emits alpha radiation. Alpha particles are energetic enough to destroy cancer cells but are unlikely to move beyond a tightly controlled target region and destroy healthy cells, according to LANL. 

Scientists at the LANL's Isotope Production Facility (IPF) recently completed a research and development project in which they explored the accelerator-based production of the isotope. Since 2005, a mission for IPF has been production of medical imaging isotopes such as strontium-82 for PET scans. The Ac-225 work adds to IPF-produced isotopes for medical therapy applications.

Historically, Ac-225 has been produced in an annual volume of between 600 and 800 millicuries through the natural decay of thorium 229 from uranium 233. But the current need for Ac-225 outstrips the supply made possible by the traditional method of production, and annual demand could reach 100 times as much, perhaps 50,000 millicuries by 2014, according to LANL. 

Production is done by a specialized particle accelerator at the Los Alamos Neutron Science Center, by irradiating thorium target foils. Scientists use a 100 MeV proton beam supplied to the Lab's Isotope Production Facility and a 200-800 MeV beam supplied to LANL's Weapons Neutron Research Facility—both of which are part of LANSCE.  

"Preliminary experiments indicate that accelerator-based production will be viable at the scale required to support clinical applications," said F. Meiring Nortier, PhD, the lead LANL scientist on the project.

The Ac-225 effort is shifting to the development of targetry and bulk-scale radiochemical processing. Research indicates that it will be possible to match current annual worldwide production of Ac-225 in just two to five days using the accelerator at Los Alamos and similar facilities at Brookhaven. Estimates are that two to three years of production scale-up and process development will be required before Ac-225 can be produced routinely.

This project was funded by the U.S. Department of Energy Office of Science via an award from Office of Nuclear Physics, Isotope Development and Production for Research and Applications.