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GLOBAL SHORTAGES OF technetium-99m (Tc99m), a radioactive isotope used in hospitals to diagnose cancer, could soon be a thing of the past thanks to radiochemists at Delft University of Technology, the Netherlands.

Hospitals are currently facing a shortage of Tc99m, forcing them to introduce waiting lists for cancer scans and delay non-urgent scans. The problem is that Tc99m is produced from molybdenum-99, which in turn is produced at only six reactors worldwide. Of these, four were temporarily shut down at the end of August: the National Research Universal reactor in Canada had to be powered down because of a storm warning, France’s Osiris reactor is on a regular maintenance shutdown, the Dutch Petten nuclear reactor has reported cooling problems, and the reactor at the Belgian nuclear research centre SCK•CEN had to be shut down on 28 August following an uncontrolled release of radioactive iodine into the atmosphere.

Writing in the university’s house magazine Delta, Bert Wolterbeek, professor of radiochemistry at Delft, explained how his work on an alternative process to manufacture Tc99m could solve a future repeat of the crisis. He points out that molybdenum-99 is produced from highly enriched uranium, the use of which is strictly limited under international non-proliferation treaties. Developing a different process route that avoids uranium would make it easier to produce Tc99m at more facilities, Wolterbeek says.

His suggestion is to produce molybdenum-99 from molybdenum-98, a stable isotope made of natural molybdenum. Wolterbeek has patented a technique in which he bombards this raw material with neutrons in order to make molybdenum-99. The molybdenum atoms are not just 'activated' by the neutron bombardment, but are also separated from the surrounding atoms by the energy transfer. The resultant molybdenum-99 can then be dissolved in water. This means that the isotope can be produced in highly concentrated form, which is crucial, Wolterbeek says: "The activity concentration of the radioactive material needs to be high, otherwise patients will be given too high a chemical dose to form a clear radiation image.”

Wolterbeek’s team is currently working to perfect the route via molybdenum-98, in the hope that the process will be commercially viable in an industrial environment. If so, the current shortages could be a thing of the past.