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THREATS TO TECHNETIUM, A DIAGNOSTIC WORKHORSE:
Aging reactors under repair // Lost access to a preferred raw material // According to some critics, government heel-dragging

Technetium: Nuclear Medicine's Crisis

By Mark Peplow // Illustrations by Tavis Coburn // Summer 2013
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technetium

Tavis Coburn

Aging nuclear reactors often struggle to stay on line, a fact that’s just as true for small research reactors as it is for massive power plants. So it shouldn’t have been surprising that during 2008, 2009 and 2010, Canada’s National Research Universal reactor in Chalk River, Ontario, and the High Flux Reactor in Petten, Netherlands, both suffered a lot of downtime. In May 2009, a heavy-water leak at NRU shuttered the facility for 15 months, while cooling system leaks and repairs kept HFR from operating from August 2008 to February 2009, another month in 2009 and six more in 2010.

Those outages might have been mere footnotes in the recent history of the nuclear industry. But the Canadian and Dutch reactors happen to be the principal sources of technetium-99m, the most widely used radioactive isotope in medicine, and their troubles led to an acute global shortage of the element that began in 2009. Karen Gulenchyn, chief of nuclear medicine and molecular imaging for the hospitals of Hamilton, Ontario, was at the sharp end of the crisis. She remembers a time of frantic triage: swapping patients’ appointments, running clinics on weekends, replacing state-of-the-art tests with less effective alternatives.

Technetium is a staple of imaging for diagnosing and monitoring several life-threatening conditions. In cardiology, it’s used to investigate complaints of acute chest pain. Bone scans to detect cancer are another major application, and for pediatric patients in particular, potential alternatives often can’t be used, because they would expose children to excessive radiation. Confirming breast cancers is still another use for which the medical isotope is well suited.

Gulenchyn, testifying about the technetium shortage to the Canadian Parliament in June 2009, described the impact. She said that it had led to limitations in diagnostic testing, a crucial part of a process that begins with a patient complaint, is followed by a history and physical examination, and culminates in diagnosis and treatment. Removing a vital link in that chain reduced certainty about what might be wrong with a particular patient and could result in misdiagnosis—possibly with fatal consequences. “Did people die? Probably,” she says.

Eventually, both reactors were back in business, and supplies of technetium returned to normal. But those days of crisis could return. Even if the reactors don’t suffer additional unplanned downtime, they’re both nearing the end of their useful lives. NRU will cease production by 2016, and HFR around 2020. And with conventional sources of technetium already under pressure, a collision between politics, business and science is forcing a shake-up in the way this essential isotope is made, and in the path it takes to hospitals and outside imaging centers. They have just a few years to secure new sources of technetium before serious shortages begin to bite once more. “I’m nervous about the relatively short time period,” says Vasken Dilsizian, chief of nuclear medicine at the University of Maryland Medical Center in Baltimore. “The process has to move faster.”

Technetium was discovered in 1937, born in a particle accelerator at the University of California, Berkeley. It was the first man-made element, and the isotope technetium-99m was created the following year. Technetium-99m emits gamma rays—similar to diagnostic X-rays—that are detected with a gamma camera. An injection of the isotope can produce real-time images of a beating heart, reveal the presence of bone diseases and even help guide a cancer surgeon’s scalpel. Every year, physicians in the United States use technetium in almost 20 million medical tests, and every one of them is a race against time. With a half-life of just six hours, batches of radioactive technetium dwindle to nothing within days. So the tests rely on a complex supply chain starting at a handful of nuclear reactors around the world that make molybdenum-99, a longer-lived precursor to technetium-99m.

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1. “The Supply of Medical Radioisotopes: The Path to Reliability,” by the Organisation for Economic Co-operation and Development and the Nuclear Energy Agency (2011). This report unpacks the problems with the technetium-99m supply chain and makes recommendations about how to reform it. 


2. “Medical Isotope Production Without Highly Enriched Uranium,” by the Committee on Medical Isotope Production Without Highly Enriched Uranium, National Research Council, The National Academies Press (2009). A comprehensive survey of the alternative technologies to make technetium-99m without a material bound to be in increasingly short supply. 


3. “Radiotracers for SPECT Imaging: Current Scenario and Future Prospects,” by S. Adak et al., Radiochimica Acta, February 2012. A review of PET and SPECT technologies, their medical uses, and the potential for growth in the use of SPECT imaging, which would necessitate yet more technetium.

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