By Jens Odegaard
Every day, approximately 40,000 people in the United States — nearly enough to fill Oregon State University’s Reser Stadium to capacity — receive a nuclear medicine imaging procedure using a radioisotope that is in high demand. Known as technetium 99m — or Tc-99m — eight of every 10 nuclear medicine imaging procedures worldwide rely on it.
“Famously, it’s used in what is called a ‘stress test,’” says Steven Reese, director of the Oregon State Radiation Center and an associate professor in the College of Engineering’s School of Nuclear Science and Engineering. “The idea is that you run on a treadmill and then get injected with Tc-99m, which is attached to a molecule that follows the flow of blood. Radiation detectors are then placed around the body so we can see how the heart moves the blood. It uncovers a lot of vital and accurate information for physicians.”
The brain, bones, kidneys and lungs are also commonly imaged using Tc-99m. But there’s a hitch in getting the product to people who need it. The Tc-99m supply is bottlenecked, and the entire U.S. supply is being imported from overseas.
A quick technical lesson: Tc-99m is a decay product of molybdenum-99 (Mo-99). That is to say, Mo-99 turns into Tc-99m as it emits radiation. So to produce Tc-99m, Mo-99 must be made first. Mo-99 is traditionally produced in large nuclear reactors by using the neutrons from the reactor to bombard a uranium-filled container called a target. As the uranium in the target fissions, one of its daughter products is Mo-99. The sole North American producer of Mo-99 shut down in 2018.
It occurred to Reese that Oregon State’s 1.1 MW TRIGA reactor could possibly be used to produce Mo-99. It was a wild idea because the TRIGA reactor is much smaller than reactors traditionally used for producing commercial quantities. Additionally, efforts are well underway to stop using high-enriched uranium in research reactors like Oregon State’s. This means that low-enriched uranium would need to be used in the target. Together, these challenges meant that it would take a novel target design to make a useful amount of Mo-99.
Reese looped in Todd Palmer, professor of nuclear engineering, who specializes in modeling and simulation. “The original target design is just like a cylindrical can that contains a layer of uranium in it,” Palmer says. “It just seemed to beg for a little innovation, you know?”
Reese and Palmer brainstormed a new target design idea and turned it over to Madicken Munk for simulation. At the time, she was an undergraduate student working for Palmer. After hundreds of simulations and numerous consultations with Todd Keller, OregonState reactor administrator, to discuss the practical implications of how the target would work in reality, they arrived at the final design.
Because of the huge commercial potential for producing Mo-99 in research reactors in the United States, patents were filed and a company, Northwest Medical Isotopes, was formed to bring the technology to market. Today, NWMI is moving forward with plans to construct a processing and production facility in Missouri, an ideal central location for shipping Mo-99 to medical facilities around the country.
Larry A. Mullins, former president and chief executive officer of Samaritan Health Services and executive chairman of Northwest Medical Isotopes, has been involved with the project since its inception. “We realized the potential early on and were very fortunate to have a partner like Oregon State University, not only for the research and development phase but also for the regulatory and intellectual property rights activity,” he says.
Brian Wall, assistant vice president for Research, Commercialization and Industry Partnerships at OSU, adds that NWMI demonstrates how technology transfer can bring an essential product back to the U.S. “It is a great example of Oregon State’s focus on maximizing our innovation and economic impact for the benefit of society.”