“I remember in Geneva, two months ago, we said: ‘Pay attention, because in this specific week there is a risk of shortage if there is some problem with one of the active reactors’ – and this is what happened” , recalls David Crunelle. , spokesperson for Nuclear Medicine Europe (NMEU), an industry association.
Due to their very nature, it is impossible to accumulate these radioactive substances: they are fleeting. Technetium-99m works as a radioactive tracer because, as it decays, it emits gamma rays with a photon energy of 140 KeV. This is “pretty ideal” for detection using a gamma-ray camera, says Cathy Cutler, head of isotope research and production at Brookhaven National Laboratory in the US.
But technetium-99m has a very short half-life, just about six hours. That’s why radioisotope production facilities send miniature generators containing molybdenum-99 to hospitals. These generators, sometimes called “moly cows,” produce the desired technetium-99m as the molybdenum-99 decays, somewhat like a portable vending machine of technetium-99m, which runs out after about two weeks, once the molybdenum-99 has completely depleted. decayed.
Glenn Flux, head of radioisotope physics at the Royal Marsden Hospital and Institute of Cancer Research in London, says that what makes a technetium-99m scan different from, say, a CT scan or an MRI, is that it reveals how patients’ organs or a tumor function, for example by revealing blood flow to the area in question.
“The CT scan will show you if there is a tumor, but the technetium or other isotopes will tell you if it is active or aggressive,” explains Flux.
The recent shortage of radioisotopes has caused the cancellation of several thousand appointments in the UK alone, estimates Stephen Harden, vice-president of clinical radiology at the Royal College of Radiologists (RCR). Healthcare staff sprang into action to distribute remaining supplies of radioisotopes across the UK, to ensure that the most urgent patients – those with cancer, for example – were still able to have their scans. “If there hadn’t been a nationally coordinated policy, there would have been significant regions of the country without any supplies,” Harden says.
Crunelle and colleagues at the NMEU continuously monitor the production of medical radioisotopes at key reactors around the world. They learn about maintenance schedules well in advance, and as such, NMEU often advises reactor bosses to push back these dates slightly, for example to minimize the risk of multiple simultaneous shutdowns. NMEU staff use software, a kind of reactor maintenance calendar, that allows them to predict production levels. But sometimes unpredictable events happen, like the plumbing problem in Petten.