Reactor shutdown may lead to Mo-99 shortage

Changes to the worldwide supply chain of molybdenum-99 could lead to drastic shortages of a nuclear medicine tracer over the next 18 months, according to a U.S. National Academy of Sciences report. The National Research Universal reactor in Ontario will shut down at the end of October, and while global supply will be “adequate," the reports judges a 50 percent chance of a substantial shortage until other suppliers complete upgrades.

Molybdenum-99, the parent nuclide of Technetium-99m, is used in more than 16.7 million nuclear medicine procedures in the U.S. each year. Technetium has a half-life of just six hours—making it perfect for nuclear imaging but impossible to stockpile. Instead, facilities like the reactor in Ontario produce molybdenum-99, which has a half-life of nearly three days. The molybdenum is shipped to hospitals or clinics, and the technetium is extracted onsite with a device called a “technetium cow.”

In addition, the extremely limited number of suppliers means certain steps in the supply chain are vulnerable. Some 95 percent of the world’s molybdenum is produced in seven plants around the world—but the plants are not in good shape. Four are over 50 years old and three are making large-scale changes and upgrades, so unanticipated shutdowns are a distinct possibility according to the report.  U.S. government entities have tried to stimulate U.S. involvement in the molybdenum market, but there are regulatory and financial issues warding off American companies.

While the Ontario reactor will be on emergency standby, a technetium shortage will still incur substantial clinical and financial costs. In 2009 and 2010, the U.S. experienced a shortage of molybdenum due to foreign reactor shutdowns, leading to the disruption or delay of procedures for an estimated 50,000 patients per day.

“If possible, we would shift to other nuclear tracers even if it gave us less-optimal images,” said University of Chicago Chief of Nuclear Medicine Daniel Appelbaum, MD, speaking about past shortages. “However, not all studies have that possibility. Even the one’s that do, there’s usually some logistical issue, some disadvantage.”

If alternative tracers are out of the question, switching to a different imaging modality can provide a solution, although that strategy still has downsides.

“We could shift a heart or bone patient to a PET scanner, but there’s less availability. We have seven gamma cameras, but only one PET machine,” said Appelbaum. “There’s a reason they were ordered as nuclear tests first.”

However, much of the time the solution is simple: the patient doesn’t receive the test, or the test is delayed.

“Sometimes it isn’t required, the doctors are able to use blood work or clinical information to make their decision,” said Appelbaum.

To avoid these scenarios, radiology departments should ensure contingencies are in place—especially through the next 18 months, until upgrades are complete in French and South African reactors.

“There’s lots of unknowns and it raises the threat level a bit, but we’re talking about it, keeping an eye on it. This shutdown can give us time for advance planning—as opposed to the past where there have been emergency shutdowns,” said Appelbaum.