Prime Minister Stephen Harper says that Canada will be getting out of the medical isotope business.

Canada produces at least one-third of the world's medical isotopes, which are used in cancer and heart scans, at the aging Chalk River facility.

At a news conference, Harper said that the plan is to bring Chalk River, now out of service, back online and working as long as possible, while working with the global community and private business for alternatives sources.

Officials say the Chalk River reactor is planned to continue operating until 2016, at which point other countries and businesses would take over to meet global demand.

Harper said it was a difficult decision but hundreds of millions of dollars thrown at the alternatives sources of medical isotopes weren't working and didn't produce a single isotope.

"For whatever reason, Atomic Energy was not able to make that project work. There was no prospect that it would work," Harper said.

"What we've decided to do instead was to invest money to repair the (Chalk River) reactor to keep it online for a longer period of time while other sources around the world come online.

"But obviously we will continue to have difficulties with a reactor that is very old, and whose operation is not always dependable and predictable ... That's just the tough reality of the situation."

Since the NRU reactor at the Chalk River nuclear facility was shut down on May 15, Canadian hospitals have been getting by with extra shipments from reactors elsewhere around the world.

The Petten reactor in the Netherlands -- the world's second largest for medical isotopes -- has increased production by at least 50 per cent, and a South African reactor has also ramped up production.

But last week, both those reactors were shut down temporarily, worsening Canada's supply crisis.

The issue is front-and-centre in Ottawa, with the head of the Ontario Association of Nuclear Medicine warning that smaller hospitals are expected to run out of medical isotopes by Thursday.

"At the end of this week, we'll have a very severe reduction in the supply of medical isotopes for this Thursday and Friday," Dr. Christopher O'Brien told Canada AM Wednesday.

"Many centres across Canada will be offering basically only emergency services -- if that."

That means some patients across Canada who have been booked for diagnostic scans for later this week may have to be rescheduled.

Natural Resources Minister Lisa Raitt said that hospitals will receive medical isotopes next week.

"Hospitals will receive next week over 50 per cent of their orders . . . from what they have anticipated," Raitt said Wednesday.

On the attack

The Conservatives also went on the attack Wednesday, charging that the Liberals knew the Chalk River reactor was near-death while they were in power.

The Tories say that former Liberal natural resources minister Ralph Goodale knew about the reactor's problems in 2003, and alleged that the minister knew that two replacement projects were in deep trouble.

Raitt called it "unforgivable" and said the Liberals didn't fund Atomic Energy of Canada properly.

Goodale responded by saying all of the reactor problems have occurred since the Tories came to power.

The Liberals said the Conservatives don't have a long-term solution to the isotope shortfall.

"We have spoken to the Dutch and the Australians and they say they can ramp up production, but they can't make up the shortfall," Liberal Leader Michael Ignatieff charged in the House of Commons Wednesday. "(The government) can't make up the shortfall and they can't say how many isotopes will actually end up in Canadian hospitals."

Other technologies

Doctors have been able to use an older-technology isotope called Thallium 201 for cardiac therapies and tests, so care for those patients has been little affected. But any type of diagnostic test for non-heart-related issues, such as cancer tests, will not be available when the supply runs dry.

Hospitals in remote areas will feel the pinch more than those in urban centres, which can pool their isotopes more effectively because of their proximity to one another.

O'Brien says his group is getting reports that next week will be even worse than this week, with absolutely no medical isotopes availability for smaller hospitals.

The Chalk River reactor will be shut down for at least three months as maintenance crews attempt to patch a crumbling wall at the base of the reactor that led to a heavy water leak.

To make matters worse for Canadian doctors desperate for isotopes, the Petten reactor in the Netherlands is also leaking and is scheduled to be out of service for four weeks starting in July.

"The shutdown of the reactor in the Netherlands is going to have a significant impact," says O'Brien.

"We're very, very concerned about this. If Chalk River is not restarted by that time, the world's two major reactors that produce medical isotopes will be closed simultaneously. The other two or three reactors that we can rely on will not be able to meet demand.

"We are terrified of this situation."