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.