“I remember two months ago in Geneva we said, ‘Be careful, because this particular week there is a risk of shortages if there is some problem with one of the active reactors’ – and that’s exactly what happened,” recalled David Crunelle, spokesman for the industry association Nuclear Medicine Europe (NMEU).
Due to their nature, these radioactive substances cannot be stored – they are volatile. Technetium-99m acts as a radioactive tracer because as it decays it emits gamma rays with a photon energy of 140 KeV. This is a “pretty ideal” solution for detecting gamma rays with a camera, says Cathy Cutler, manager of isotope research and production at Brookhaven National Laboratory in the US.
However, technetium-99m has a very compact half-life, just six hours. That is why radioisotope production plants send miniature generators containing molybdenum-99 to hospitals. These generators, sometimes called “molybdenum cows,” produce the desired amount of technetium-99m as the molybdenum-99 decays—kind of like a portable technetium-99m vending machine that runs out of stock in about two weeks when the molybdenum-99 is completely depleted. broken.
Glenn Flux, head of radioisotope physics at London’s Royal Marsden Hospital and the Institute of Cancer Research, says what distinguishes a technetium-99m scan from, say, a CT scan or MRI is that it reveals how a patient’s organs or tumor function – for example by revealing blood flow to an area.
“The CT scan will show whether there is a tumor, but technetium or other isotopes will tell whether it is active or aggressive,” Flux explains.
The recent shortage of radioisotopes has resulted in 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). Health staff have stepped in to distribute the remaining stock of radioisotopes across the UK to ensure that the most urgent patients – such as those with cancer – can still participate in trials. “If there were no nationally coordinated policy, there would be significant regions of the country without supplies,” Harden says.
Crunelle and colleagues at NMEU continuously monitor the production of medical radioisotopes at key reactors around the world. They learn about maintenance schedules well in advance, and as a result, the NMEU often advises reactor managers to shift these schedules slightly – for example, to minimize the risk of multiple shutdowns occurring at the same time. NMEU employees employ software that acts as a kind of reactor maintenance calendar that allows them to forecast production levels. But sometimes unpredictable events happen, such as the pipe problem in Petten.