Canada to Develop New Isotope Production Methods

An aging reactor and a worldwide looming shortage of medical isotopes has driven Canada to search for alternatives methods to manufacture technetium-99m (^99mTc).

At the moment, Canada's only source of the isotope is the National Research Universal (NRU; Chalk River, Ontario, Canada) reactor at Chalk River Laboratories (CRL, Ontario, Canada), which produces about a third of the world's supply. But the reactor has been plagued with safety and operational problems, leading to worldwide shortages, and its license is set to expire in 2016. Consequently, Canada is investing close to USD 21 million in three projects in western Canada that have demonstrated the ability to produce the key medical isotope without a nuclear reactor.

Two of the research institutes, the national laboratory for particle and nuclear physics (TRIUMF; Vancouver, BC, Canada) and the University of Alberta (Edmonton, Canada) are using cyclotron technology to produce the isotope, while the third, Prairie Isotope Production Enterprise (PIPE; Pinawa, MB, Canada), is using a linear accelerator.

In the cyclotron process, the machine bombards a target of molybdenum-100 with high-energy protons, converting some of its atoms to molybdenum-99 (Mo-99). Then chemical processing removes technetium-99 from the target, ready for use. The PIPE technology uses an electron accelerator rather than a nuclear reactor to make the Mo-99. The electron accelerator sprays electricity onto molybdenum metal, which produces the Mo-99 radioisotope. Next, a chemical process is used to fabricate the Tc-99m.

“The Harper Government is investing in Canadian expertise to help ensure new sources of supply for medical isotopes used in diagnosing various diseases, such as cancer and heart disease,” said Joe Oliver Canada’s natural resources minister. “We are investing in the work needed to attract private sector interest and to bring new technologies to market, and to help ensure that isotope production is on a sound commercial footing.”

Tc-99m is obtained from the decay of its parent isotope Mo-99 compounds that are packed into nuclear "generators" and distributed to hospitals, where nuclear medicine specialists can draw off the Tc-99m as needed for about a week. Tc-99m is used in 80% of nuclear medicine diagnostic procedures in Canada, and about 85% of all medical imaging procedures worldwide. It is currently made in reactors in Canada, the Netherlands, Belgium, France, Australia, and South Africa.

Related Links:
National Research Universal
TRIUMF
Prairie Isotope Production Enterprise