What's more, scores of thyroid cancer patients have been deprived of radiotherapy involving isotopes that are no longer available.
"No one has died in Quebec because of this crisis, but if it continues, that could happen," warned FranÃ§ois Lamoureux, president of the Association de medecins specialistes en medecine nucleaire.
On average, Quebec hospitals carry out 12,000 diagnostic tests for cancer and cardiac disease each week using Technetium-99 and other isotopes. However, since Ontario's Chalk River nuclear reactor - the world's biggest producer of medical isotopes - shut down in the middle of May because of a leak, that supply has dwindled steadily.
"We can safely say that 50 to 60 per cent of tests have been put off since the beginning of the crisis, which would be the start of June," Mr. Lamoureux said.
In fact, Quebec's supply of isotopes is now down to about 20%. Experts in nuclear medicine have said that if a jurisdiction's supply drops to below 50%, deaths are inevitable.
Hospitals in Ottawa and Manitoba have also said they will soon run out of medical isotopes, with high-priority patients expecting lengthy delays and low-priority patients being bumped even further down the list.
Fortunately for patients served by Northern Health in British Columbia, the organization of roughly 20 hospitals recently started getting its isotopes from a supplier based in The Netherlands just before the Chalk River shutdown.
"We have been able to maintain services and haven't had to cancel any patients," said Ken Winnig, director of diagnostics for Northern Health. "We switched to the Netherlands supplier just before the Chalk River incident. We've been told that we'll be able to get another generator for next week, which means we'll be fine for the next while," he said, adding that the province also has a working group which manages the supply and ensures that any extra isotopes are transferred to facilities in need.
Hospitals in bigger cities, such as the University of Alberta Hospital, are faring better than those in areas with smaller populations. A spokesperson for the university hospital said that while the facility has been affected, the shortage has not been as drastic because the hospital is in a big centre and produces its own isotopes.
Facilities in smaller centres face geographic barriers to access of isotopes produced by nearby generators, and are forced to improvise by doing alternate exams that do not require isotopes, or use a different kind of isotope altogether, Mr. Winnig explained.
Prime Minister Stephen Harper says Canada plans to leave the production of medical isotopes to other countries.
"Eventually, we anticipate Canada will be out of the business," Mr. Harper said.