On an average day, a dozen or so patients arrive at the sprawling Maine Medical Center in Portland for bone scans, tests for heart or gallbladder problems, or dozens of other tests performed with the radioactive isotope technetium-99m. When injected into a patient’s vein, TC-99m, mixed with a “tracer” chemical, knows exactly which part of the body to target. From there the radioactive isotope emits gamma rays that transmit an image to a camera, enabling specialists to check for tumors, gauge blood flow through the heart, monitor kidney function or examine a number of other conditions.
TC-99m is a diagnostician’s dream: It produces what Chet Bradbury, who as Maine Med’s chief nuclear medicine technologist often uses such isotopes, calls a “pretty picture.” By that he means the image’s exceptional clarity makes a medical decision easy to reach.
It’s also ideal for patients. The high-quality image is reliable enough to frequently bypass exploratory surgery. And because TC-99m is active so briefly, patients receive minimal amounts of radiation.
Each year in the United States, about 22.5 million nuclear medicine diagnostic procedures are performed; of those, about 18.5 million use TC-99m. But despite the isotope’s crucial role in detecting life-threatening diseases, few countries produce it and supplies at times run dangerously low.
Many experts say it doesn’t have to be that way. In fact, they insist, a different method of production must be developed. To appreciate why, you must first understand the current production system.
Today companies in only five countries—Canada, the Netherlands, Belgium, France and South Africa—produce medical isotopes. The United States used to, but hasn’t since 1989, when the sole domestic manufacturer, in Tuxedo, N.Y., closed because its reactor was leaking radioactivity.
While the United States has no facility for producing the isotopes, it does have something the five global producers do not have: An abundance of the raw material used in processing TC-99m. That material is highly enriched, weapons-grade uranium.
To the dismay of officials in charge of anti-terrorism efforts, the U.S. government each year ships about 187 pounds of highly enriched uranium—the stuff of nuclear bombs—from its weapon stockpiles to the isotope-producing countries. The bomb dropped on Hiroshima contained about 140 pounds of highly enriched uranium.
Of the U.S. shipments, about 44 pounds reaches the National Research Universal reactor in Chalk River, Ontario. There, the uranium is bombarded with neutrons, yielding the metal molybdenum-99. The molybdenum-99 is placed in lead-shielded cylinders and immediately shipped to nuclear pharmacies around the world, including 500 in the United States. The pharmacies then extract the TC-99m isotope to be injected in patients.
The United States typically gets about 60 percent of its supply of molybdenum-99 from Chalk River and another 40 percent from the High Flux Reactor (also known as Petten) in the Netherlands. When the United States halted production of TC-99m, Canada offered assurances that it could meet U.S. demands. Canada promised to build two reactors near the Chalk River facility, which began operating in 1957.
Those two backup reactors never began operating. After millions in cost overruns, delays and serious safety issues, Canada permanently mothballed the reactors and declared its intention to get out of the isotope business entirely.
A report released in January 2009 by the National Academy of Sciences painted an alarming picture about the unreliability of supplies from Chalk River and the other major U.S. supplier, the 48-year-old reactor in the Netherlands. (The reactors in France, Belgium and South Africa are almost as old.) The findings fueled calls for the United States to pursue its own domestic isotope supply.
Far sooner than anyone predicted, that need became apparent.
May day, May day
In mid-May, Chalk River abruptly shut down after a small leak was discovered. The reactor isn’t expected to restart until the first quarter of 2010. Then in July, the U.S. backup supplier—the Dutch Petten reactor—also shut down briefly for routine maintenance.
Suddenly, the supply of TC-99m isotopes used in some 46,000 procedures each day in this country was in jeopardy. Nuclear medicine providers predicted dire consequences for patients. “It’s possible that some deaths could occur,” Michael Graham, M.D., president of the Society for Nuclear Medicine, told reporters. “Some people will be operated on that don’t need to be, and vice versa.”
Hospitals around the country braced for the worst.
Disaster waiting to happen
For decades, U.S. security experts have braced for another kind of disaster with the same uranium. The United States began circulating highly enriched uranium around the world in the 1950s under its Atoms for Peace program, which promoted civilian nuclear development. Though any alleged disappearance of uranium is difficult to confirm, growing concerns about the potential for theft prompted the government to reverse course in the 1970s. It began retrieving distributed uranium, especially from countries where terrorism was a threat, such as Serbia and Bulgaria.
The government also stopped shipping highly enriched uranium—with one notable exception: distribution continued for production of medical isotopes. Today that distribution poses an increasingly attractive target for terrorists. “This 1950s-era policy simply does not work in a post-9/11 world,” says U.S. Rep. Edward J. Markey, D.-Mass., a long-time advocate for nuclear safety. “It is dangerous and unnecessary and must come to an end.”
Only about three percent of highly enriched uranium is actually consumed in the processing. The remainder, waste that can still be used to make nuclear weapons, is stored at the reactor facilities. While in recent years the United States has spent millions to upgrade its own storage of highly enriched uranium, security at foreign reactors isn’t nearly as good.
“It’s bomb-grade material,” says Alan J. Kuperman, director of the Nuclear Proliferation Prevention Program at the University of Texas, “but it’s not guarded like bomb-grade material.”
The most logical solution, from a security standpoint, would be to switch production sources from highly enriched uranium to low-enriched uranium. The lower-grade metal yields medical isotopes of equivalent quality and can’t be converted into nuclear weapons.
Past efforts to make this change, however, met resistance, in part because converting existing reactors to be able to use low-enriched uranium will be expensive. Among those opposing the change in Washington was MDS Nordion, a Canadian company that supplies 40 percent of the world’s supply of medical isotopes from Chalk River.
Earlier this decade, when Congress was considering extending restrictions on exports of highly enriched uranium, MDS Nordion and another isotope manufacturer launched an extensive lobbying campaign to ease the restrictions, according to the Washington Post. Leading the effort in Congress to keep the uranium in circulation was Richard Burr, R-N.C., then a U.S. representative and now a senator.
The effort succeeded. The 2005 Energy Policy Act, signed by President George W. Bush, exempted material used for medical isotopes from the restrictions—effectively undermining, critics said, a quarter-century of U.S. efforts to halt the global trade.
But the 2005 energy act contained something else: A request that the National Academy of Sciences (NAS) determine the technological and economic feasibility of producing medical isotopes with low-enriched uranium. In January, accompanying its bleak appraisal of current sources of medical isotopes, the NAS concluded that the isotopes can indeed be produced from low-enriched uranium.
That news, coupled with the summer’s production problems in Canada and the Netherlands, gave backers of using low-enriched uranium an opportunity to break the decades-long stalemate. “It was fortuitous that the supply interruption occurred and got things moving,” Kuperman says.
Interested parties who often had been at odds—nuclear medicine specialists, national security experts, politicians and scientists–began to collaborate on what became the American Medical Isotopes Production Act. Markey and Rep. Fred Upton, R-Mich., introduced legislation last summer, and the House passed the bill Nov. 5. The measure still requires Senate action and President Obama’s signature to become law.
It would provide $163 million over five years to establish domestic production of molybdenum-99 from low-enriched uranium. It also sets a timeline to phase out highly enriched uranium exports for medical isotope production. And the Obama administration has committed an additional $20 million in funds to speed the conversion
Foreign producers see the handwriting on the wall. In September, a top Department of Energy official testified that the foreign makers of isotopes have approached the United States for financial and technical assistance in converting to lower-grade uranium.
As for the dire shortages of isotopes predicted this summer, most hospitals around the country fared relatively well, although certain regions, including the Midwest, experienced shortages. Belgium, France and South Africa increased output to meet demand. Doctors ordered doses of TC-99m more efficiently and used alternative isotopes for certain diagnostic tests.
“It was not the huge crisis that we were concerned about,” Graham says.
That doesn’t mean that supply problems won’t crop up again soon, warns Jeffrey Norenberg, executive director of the National Association of Nuclear Pharmacies. Chalk River’s future is uncertain. And things “will go from bad to worse” early next year when the Netherlands reactor begins a scheduled six-month outage, Norenberg says.
He’s hopeful new isotope reactors in Australia and Argentina—which both use low-enriched uranium—will eventually be certified by the U.S. Food and Drug Administration and be able to fill up to 15 percent of U.S. demand for TC-99m.
At Maine Medical Center, Chet Bradbury worries, too. Although supply problems haven’t inconvenienced his patients so far, he says, that may change. “As to what our pharmacy can get, it will be on a week-to-week basis, based on production worldwide.”
Susan Q. Stranahan is a freelance writer who lives in Maine.