FDA clears U.S. medical isotopes supply
Domestic production could end delays in nuclear medicine scans
For decades, U.S. health providers have relied on a fragile international supply of the medical isotopes needed for nuclear imaging scans, which are critical for seeing how the body’s internal organs are operating in real time. But frequent shutdowns of the reactors producing the isotopes have created abrupt and sometimes lengthy delays that forced hospitals and clinics, including some in Central Oregon, to delay scans or use less reliable tests.
That could soon change now that the Food and Drug Administration has cleared the way for the first domestic production of medical isotopes in 30 years. The agency announced last week it had approved the RadioGenix System, developed by Beloit, Wisconsin-based NorthStar Medical Radioisotopes, to produce technetium-99m, the most widely used isotope in medical imaging. The isotope is used to evaluate coronary artery disease, cancer progression and lung, liver, kidney and brain function.
St. Charles Health System performs about 130 to 150 exams using technetium each week at its Bend and Redmond hospitals but experienced shortages at various times over the past few years. Generally, that delayed scans for only a day or two. The last shortage occurred just in the past few weeks.
“It’s used for so many procedures here that when there’s a shortage, it’s tough. We have to kind of delay exams, or choose a different exam that may not be as helpful to the physician,” said Mike Timmerman, radiation safety officer at St. Charles. “We’ve had some minor shortages recently, but nothing like the ones around 2010.”
Those shortages prompted Congress to pass the American Medical Isotopes Production Act of 2012 to support the development of a domestic supply, but sporadic shortages have continued to plague hospitals and clinics. Those shortages are similar to those being experienced by the St. Charles hospitals in Bend and Redmond, said Dr. Jeanne Link, director of Oregon Health & Science University’s Center for Radiochemistry Research in Portland.
“It has impacted the entire U.S., not just the West coast, not just rural areas,” Link said Technetium is derived from another radioactive isotope, molybdenum-99. Before last week, the only source of molybdenum was from reactors processing enriched uranium outside of the United States. The molybdenum is delivered to hospitals in a technetium generator, known as a moly cow, and technetium-99m is then milked from the generators as needed by the hospital.
Molybdenum has a half life of 66 hours, and is better suited for transport over long distances than technetium which has a half-life of only 6 hours. And once the technetium is extracted, it must be used fairly quickly before it degrades.
In recent years, suppliers have set up regional radiopharmacies that extract doses of technetium and then deliver them to hospitals as needed. St. Charles now relies on both methods, ordering some single doses, but also extracting its own technetium from generators.
“Technetium is really the workhorse in nuclear medicine, so it’s bad when we don’t have it for patient cases,” Link said. “Having a supplier that’s in the U.S. should help.”
Nuclear medicine is one of the few imaging tests that allow doctors to see how the body is functioning, rather than looking at a single snapshot in time. Despite the name, the tests expose patients to less radiation than a typical CT scan.
Some tests, such as those looking for bone abnormalities, can be delayed for a week with little impact to the patient. But other tests need to be done immediately to provide the best patient outcomes.
“If you’re doing a cardiac scan, this is a patient where they’re worried about blood flow and whether there has been heart damage,” Link said. “The use of this agent will help them decide whether it’s worthwhile, whether the tissue is dead, or whether it could go through surgical intervention … to open up the blood vessel and save the tissue.” If the scan is unavailable, the patient could wind up undergoing an unneeded or futile procedure.
NorthStar officials said they expect to be shipping product to radiopharmacy customers within several weeks. Initially, the company is expected to supply about 10 percent of the domestic demand for the isotopes, but could account for up to two-thirds of demand as they increase production. At least two other companies seeking to produce technetium in the U.S. are working with the FDA to get approval.
The cost of generating technetium from a RadioGenix System, the company said, is similar to that of current generators. But the cost of isotopes could drop over time if worldwide production increases with the addition of U.S. production. The new production method carries the added benefit of not requiring highly enriched uranium, which raised concerns about diversion to create dirty bombs or other primitive nuclear devices by terrorists or rogue states.
Summit Medical Group uses technetium to perform about 30 nuclear stress tests a week to measure blood flow to the heart. During the last supply disruption, the clinic had to reschedule 12 patients but were able to get those patients back in within a week.
“If there’s an actual shortage of isotope production, usually we’ll get a warning or notification a few days ahead of time,” said Dr. Rick Koch, a cardiologist who serves as medical director for the clinic. “It doesn’t mean we can’t do tests, but we have to switch to a different agent.”
Usually that means using thallium, another radioactive isotope that was used in the past. Technetium, he says, gives better results.
“I think there’s a number of us who’ve wondered why we haven’t had a U.S. source for this,” Koch said. “There have been a number of times we’ve been left in the lurch.”
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