OTTAWA - Canada's leading nuclear medicine company plans to import a back-up supply of isotopes from Russia so that patients can continue to get important medical tests in the case of another domestic nuclear reactor shutdown.

MDS Nordion (TSX:MDS) said Thursday it has signed a deal with JSC Isotope, a subsidiary of Russia's state-owned RosAtom State Corp., to provide it with a supplemental supply of Molybdenum-99, used to make isotopes for about 80 per cent of nuclear medicine procedures.

"This new supply agreement is important not only for MDS Nordion, but for the nuclear medicine community and patients around the world, as it seeks to address the need for greater stability and long term reliability in the medical isotope supply network," the Ottawa-based company said in a statement.

An extended shut-down of Canada's government-owned National Research Universal reactor in Chalk River, Ont. that lasted more than a year, restricted use of MDS' medical imaging diagnostic tool used on patients to test for cancer and other diseases.

"The agreement provides MDS Nordion with exclusive back up supply to help offset the impact of the planned shutdowns of Atomic Energy of Canada Limited's National Research Universal reactor," the company said.

The NRU reactor, which had been one of the world's few sources of medical isotopes was shut down for repairs last year, and reopened in August.

Last year's shutdown created uncertainty in the nuclear medicine industry and caused a political storm in Ottawa. The federal government eventually dismissed a senior nuclear industry regulator who had shut down the reactor over safety concerns -- a position the government did not support.

The AECL initially said repairs would take "more than a month" then said the NRU reactor wouldn't be back in service before late 2009 and then early 2010.

In the meantime, MDS, which was previously a diversified life sciences company, announced in September that it would sell off most of its remaining business units to focus on its Nordion nuclear medicine business.

Shares in the company lost a penny to close at $10.33 Thursday on the Toronto Stock Exchange.