According to the World Nuclear Association, more than 10,000 hospitals worldwide use radioisotopes in medicine. Molybdenum-99, the parent isotope of technetium-99m, is the most widely used radioisotope for the diagnosis and treatment of cancer. However, production costs and the limited viability of the isotope can be a challenge for clinicians and healthcare providers. Now, nuclear researchers at the University of Missouri are exploring alternate materials that could be used to help recycle the metals used to produce radioisotopes more efficiently and with less waste. Scientists believe this cheaper method could result in a cost savings for healthcare providers who could pass those savings on to patients.
"Approximately 80 percent of the world's nuclear diagnostic procedures, including bone scans and myocardial stress tests, use technetium-99m to help pinpoint problems in patients," said Silvia Jurisson, professor of chemistry and radiology in the College of Arts and Science and a research investigator with MU Research Reactor (MURR). "While the use of this material has become somewhat routine, the production costs associated with producing this isotope without using highly enriched uranium is quite costly. Therefore, we're considering other metal target forms that can be irradiated to generate the same diagnostic (molybdenum-99/technetium-99m) and potentially therapeutic (rhenium-186) radioisotopes at a lower cost to suppliers."
Technetium-99m must be produced near the place and time it is used. It is formed when an irradiated metal, such as molybdenum-99, decays. The radioisotope has a half-life of 66 hours; therefore, clinicians have about three days to use the radioisotope before it is no longer viable.
Jurisson, working with Matthew Gott, a recent MU doctoral graduate, decided to build upon previous research to further test three materials: osmium, tungsten and molybdenum. The researchers believed that by chemically combining the three metals with sulfides, they could effectively produce radioisotopes while making the metal easier to reuse. Testing was conducted at MURR as well as Brookhaven National Laboratory where Gott was awarded a fellowship.
"Enriched metal target materials can cost as much as $10,000 for miniscule amounts," Jurisson said. "Therefore, finding ways to recycle and reuse these materials has become an important task. We found that the addition of sulfides to tungsten, osmium and molybdenum -- coupled with proper cooling after they had been irradiated -- helped us to recover between 88 and 93 percent of the metals while still producing the needed radioisotopes. This means that this very expensive metal can potentially be recycled to cut down on health care costs while still being effective."
Jurisson and her team have continued the research through the summer and are examining other metals to produce other radioisotopes that may have similar properties. The early-stage results of this research are promising. If additional studies are successful within the next several years, then working with physicians at MU will be warranted.
The MU Research Reactor has been a crucial component to research at the university for more than 40 years. Operating 6.5 days a week, 52 weeks a year, scientists from across the campus use the 10-megawatt facility to not only provide crucial radioisotopes for clinical settings globally, but also to carbon date artifacts, improve medical diagnostic tools and prevent illness.
The study, "Accelerator-based production of the 99mTc-186Re diagnostic-therapeutic pair using metal disulfide targets (MoS2, WS2, OsS2)" was published in the journal Applied Radiation and Isotopes. Funding for the project was provided by the U.S. Department of Energy through the Office of Science, Nuclear Physics, Isotope Program (DE-SC0007348) and trainee support was provided for Matthew got through the National Science Foundation (DGE-0965983). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.