Not a glowing outlook
While vital isotopes needed for medical imaging are back in supply, another shortage could loom as the U.S. continues to lack adequate domestic sources
When the medical isotope shortage hit its peak earlier this year, Manuel Brown, chairman of the radiology department at Henry Ford Hospital and Health Network in Detroit, remembers months when his staff didn’t know from one day to the next whether they would be able to perform nuclear imaging studies.
“There were nights when we couldn’t respond to demands from the emergency rooms for things like lung scans, which are used to diagnose pulmonary embolisms,” says Brown, who also chairs the American College of Radiology’s Commission on Nuclear Medicine. “There were some nights when we only had enough isotopes for one study, or week- ends when we couldn’t do any. It was very difficult, and it became a real problem in terms of providing good care to patients.”
The worldwide isotope shortage—well documented by now—was caused by an unexpected shutdown of Canada’s Chalk River (Ontario) nuclear reactor in May 2009 due to leakage of radioactive water. The facility, which remained closed for repairs until this past August, produces roughly half of the U.S.’ supply of molybdenum-99, a uranium-processing byproduct used to produce the medical isotope technetium-99.
More than 80% of the 18 million nuclear imaging studies performed annually in the U.S. use technetium-99 as a contrast agent.
The shortage became even more urgent when a nuclear reactor in Petten, the Nether- lands, shut down for months of maintenance work between February and September 2010. With two of the five medical-isotope-producing reactors in the world simultaneously offline, radiology providers were unable to access a sufficient supply of technetium.
As a result, hospitals and imaging centers had to postpone PET and other types of nuclear scans used to diagnose certain cancers and heart and brain conditions. In some cases, doctors and their patients had to opt for less effective imaging techniques, says Steven Larson, chief of nuclear medicine at New York’s Memorial Sloan-Kettering Cancer Center.
“We reduced by 15% to 20% the amount of technetium we used in certain procedures, but that reduces optimal imaging,” he explains. “We also used some alternative isotopes, which had been replaced by technetium because it has advantages.”
The isotope shortage has eased in recent months with the reactivation of the Chalk River and Petten facilities, but nuclear-medicine experts say unless the U.S. pushes forward with developing a domestic supply of medical isotopes, the sort of problems experienced over the past couple of years are likely to revisit in a much more pressing fashion. They note that four of the reactors producing molybdenum-99 are aging and expected to be in operation for only a few more years. The Chalk River reactor, for example, is scheduled for permanent closure by 2016.
“I think the events of the past two years have really woken us up to what the future will be if we don’t make a concerted effort to solve the problem,” says Andrew Einstein, assistant professor of clinical medicine at Columbia University Medical Center’s cardiology division.
A technician monitors production of molybdenum-99 at GE Hitachi’s Vallecitos Nuclear Center, about 30 miles east of San Francisco. The site includes a small research reactor.
Covidien Healthcare operates this isotope processing plant in Petten, the Netherlands. The temporary shutdown of a governmentowned nuclear reactor in the city contributed to the worldwide shortage of medical isotopes earlier this year.