Canadian cyclotron solution could fix isotope shortage

Canadian researchers may have a solution to the world's shortage of radioactive isotopes, essential in thousands of medical imaging procedures.

Canadian scientists have developed a method of producing an important medical imaging isotope without a nuclear reactor.

The development means shortages of technetium-99, used in about 80 per cent of medical diagnostic imaging procedures — 30 million a year worldwide — may no longer be a problem in the future.

Small particle accelerators called cyclotrons, including this one in Winnipeg, can be found at hospitals across the country. (CBC)

"Our collaboration has been able to produce a significant quantity of this isotope, which is a very exciting result, setting what we hope is a stage for a model for the rest of the world," Dr. Paul Schaffer, head of nuclear medicine at TRIUMF, Canada's national laboratory for particle and nuclear physics in Vancouver, said Monday.

Schaffer and his colleagues have found a way to upgrade cyclotrons, small particle accelerators found at hospitals across the country, to produce the isotope used in many scans use to detect and treat cancer, heart disease and other medical conditions.

What is a cyclotron?

A cyclotron is the partner technology to positron emission tomography, producing the radioisotope used during a PET scan. The radioisotopes produced by the cyclotron have a half-life ranging from two minutes to 110 minutes, which necessitates production on site for the shorter half-life isotopes.

A cyclotron operates by spinning charged particles in ever-expanding circles until they strike a target, producing the desired isotope.

Although the cyclotron produces radiation when it is turned on, the unit itself is enclosed in lead and concrete, so there is no increase in natural background radiation levels for those who work or live around or near the cyclotron facility. Cyclotrons are tightly regulated by the Canadian Nuclear Safety Commission to ensure there is no radiation risk to workers, the public or the environment.

— SOURCE: Winnipeg Regional Health Authority

The research team — which includes researchers from the BC Cancer Agency and the Lawson Health Research Institute and Centre for Probe Development and Commercialization in Ontario — spoke about their new method at the annual meeting of the American Association for the Advancement of Science in Vancouver.

Currently, 95 per cent of the world's supply of technetium-99 is produced at five nuclear reactors around the world, including the National Research Universal reactor in Chalk River, Ont.

The heavy water leak in 2009 that forced the shutdown of the NRU reactor for more than a year led to a worldwide shortage of medical isotopes, forcing the postponement or cancellation of some medical imaging scans. A similar reactor in the Netherlands was forced to shut down temporarily for maintenance during the NRU shutdown, worsening the problem.

The NRU reactor is currently back on line and producing medical isotopes, but it is scheduled to close in 2016.

Dr. François Bénard, scientific director of the Centre of Excellence for Functional Cancer Imaging at the BC Cancer Agency, said existing hospital cyclotrons could be quickly upgraded using the new method before the NRU's scheduled closure.

He and his colleagues believe nuclear reactor-produced medical isotopes will be used in the future, but regionalized networks of cyclotrons will supplement them to ensure a steady supply.