Oregon State University’s TRIGA Mark II nuclear reactor doesn’t produce power. But along with assessing radiation damage and providing support for a plethora of other scientific disciplines, it’s also very capable of producing vital radioactive medical isotopes, radioisotopes, necessary for diagnostic imaging. All matter consists of a particular combination of elements in the form of molecules and chemicals, and each element can exist as one of several radioactive or non-radioactive isotopes. Certain radioisotopes can be injected into a patient’s body to help non-invasively and non-surgically diagnose cancers in a variety of organ systems much earlier than other diagnostic techniques. Among a wide variety of other medical uses, radioisotopes can also help to determine whether your heart, lungs and kidneys are functioning properly, whether your brain is receiving adequate blood supply, and can find tiny bone fractures faster than an X-ray. These techniques are more effective, reliable, and available than alternatives such as CT scans, MRIs, and X-rays. In the U.S. alone, approximately 18 million medical procedures are performed using radioisotopes each year.
Unfortunately, radioactive medically useful isotopes can’t be held for long-term storage. Radioisotopes like those produced by OSU’s TRIGA Mark II reactor, are generally unstable, and eventually “decay” into their non-radioactive forms. A radioisotope’s half-life is defined as the time it takes 50% of the isotope to decay. Molybdenum-99 (99Mo), the most highly produced radioactive medical isotope, decays with a half-life of 66 hours to technetium-99m (99mTc), which is used directly in about 80% of diagnostic imaging procedures. The half-life of 99mTc is only 6 hours (long enough for an exam and short enough to let patients leave the hospital shortly thereafter), so medical centers in the U.S. must receive weekly shipments.
In 2009 and 2010, the world experienced a severe shortage of these tremendously important medical isotopes. The single Canadian National Research Universal (NRU) nuclear reactor producing 99Mo and other isotopes, including Cobalt-60 used in cancer treatment, was shut down for over 18 months. Also in 2010, 6 months of production time was lost in the Netherlands’ Petten reactor, which supplies 60% of Europe’s 99Mo supply. These reactors were two of only five reactors producing medical isotopes for the entire globe. While the United States consumes 50% of the world’s annual 99Mo/99mTc supply, it produces none of these medical isotopes outside of research, and instead the U.S. medical community relies entirely on shipments from outside the country, mainly from Canada. As a direct result of the shortage, fewer of these low-risk, non-invasive radioisotope diagnostic imaging procedures were performed, especially in North America, many were delayed by days to months, and the radioisotope costs of these procedures more than doubled.
Due to politics and capitalism, it’s unlikely that the U.S. will produce its own domestic supply of medical isotopes in the near future. While other countries, including Canada, subsidize and support nuclear reactors capable of producing these isotopes, the U.S. instead views such things as an “industry issue.” Admittedly, it’s expensive and risky to build larger-scale reactors capable of generating a country’s-worth of medical isotopes, even though these reactors are also hugely useful to a variety of other research fields. Two incredibly expensive reactors recently built in Canada were eventually abandoned with mechanical problems. General Electric recently quashed its own private attempt at medical isotope production citing that it was not currently economic with Canada’s NRU reactor up and running. Imagine the derision of taxpayers if a government-funded nuclear reactor capable of producing medical isotopes was built and paid for but never produced a single isotope. It gets very complicated.
The reactor here at OSU isn’t big enough to produce medical isotopes for our entire country. But small reactors like the TRIGA Mark II are becoming hugely important in other countries as we try to avoid potential future shortages and meet increasing worldwide radioisotope demands. Although the U.S. has not yet begun contributing to the global medical isotope supply, its small reactors, perhaps especially at Universities, may also be incredibly important as support in the future when larger reactors inevitably fall short.
By Genevieve Weber
See this previous Corvallis Advocate feature on the TRIGA reactor: