Nuclear medicine technologists use medical isotopes to take images used to help diagnose cancer and heart ailments. ((Chris Young/Canadian Press))

The first medical isotopes in 15 months have been produced at the nuclear reactor in Chalk River, Ont., Atomic Energy of Canada Ltd. announced.

"AECL reports that it has harvested the first molybdenum-99 isotopes from the [National Research Universal reactor] and that the reactor is in steady operation," the agency said in a release Wednesday.

The 53-year-old reactor was capable of providing a third of the medical isotopes needed worldwide until AECL shut it down in May 2009 because of a heavy water leak.

An outage that was originally supposed to last a month ended up lasting 15 months.

Doctors and others in the medical community had to scramble for alternative sources and types of medical isotopes and reschedule patients to deal with periodic shortages during the shutdown.

On Tuesday, the agency said the reactor was back up and running.

Lantheus Medical Imaging is the U.S. company that ships processed isotopes from Chalk River to hospitals and clinics in the United States and Canada. Lantheus said all of its customers will receive 100 per cent of the material they request on Monday.

Medical isotopes such as molybdenum-99 are used to diagnose cancer and heart ailments.

Shutdown caused worldwide shortage

When the NRU reactor at Chalk River was shut down in 2007 for maintenance, it caused a worldwide shortage of medical isotopes.

Since then, the other four major producers of isotopes in the Netherlands, Belgium, France and South Africa have helped make up the difference. But the isotope supply remained precarious when any of the major international reactors went down for scheduled maintenance and refuelling.

In November 2009, Natural Resources Canada's expert review panel on medical isotope production released its report calling for less reliance on Chalk River by diversifying into other sources of medical isotopes.

In April, the Conservative government said it will spend $35 million to find ways to make isotopes without a nuclear reactor, such as turning to cyclotrons and linear accelerators instead.  

The National Research Universal reactor at Chalk River is set to close in 2016.