Solving the shortage

Shortages of radioisotopes for cancer diagnosis could be eradicated thanks to a technology developed by Prof Bert Wolterbeek at Delft University of Technology’s Reactor Institute Delft (RID).

Globally, only a handful of reactors manufacture technetium-99m, the isotope used to help diagnose about 40 million patients annually. Three of these reactors are currently unable to supply any due to maintenance work, including Europe’s most important, the Dutch reactor in Petten.

The problem could be solved if more manufacturers made the isotope, but the process requires enriched uranium, which in turn requires a special permit due to nuclear non-proliferation treaties.

Wolterbeek aims to get around the problem by developing a method for producing the isotope without uranium. If these experiments prove to be applicable in an industrial environment, many more factories could manufacture the material.

Wolterbeek said: ‘Technetium-99m, the material in question, is currently made by highly enriched uranium fission.

'One of the products created is radioactive molybdenum-99, the raw material for technetium-99m. Manufacturers supply this molybdenum to hospitals secured in rods. A hospital can ‘harvest’ the technetium-99m isotope from a rod for a week as the molybdeen-99 slowly decays into technetium-99m.’

However, molybdenum-99 can also be manufactured from molybdenum-98, a stable isotope made of natural molybdenum, a material that mining companies already extract from the ground.

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, meaning that the isotope can be produced in highly concentrated form. This aspect is crucial, as Wolterbeek said: ‘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.’