Technetium-99m (Tc-99m) is used in 30 million medical imaging procedures a year – roughly one procedure per second – making it the most extensively used radioisotope for medical diagnostics in the world. But a looming isotope shortage, which has garnered national attention, will pose serious problems for future technicians and researchers.
One Western researcher, however, may provide a solution.
Medical Biophysics professor Michael Kovacs, part of a cross-Canada collaboration (Vancouver, Hamilton and London) with five other scientists, is addressing the scarcity of Tc-99m, which is currently used to diagnose cancer and heart disease. The group recently received the 2015 Brockhouse Canada Prize for Interdisciplinary Research in Science and Engineering for their work.
“We throw around the word ‘isotope’ kind of loosely. Generally, what we mean is ‘radioactive isotopes,’ which are unstable isotopes that undergo a process called radioactive decay, where eventually they want to become stable,” said Kovacs, a Lawson Health Sciences Centre researcher and director o the Nordal Cyclotron and PET Radiochemistry Facility at St. Joseph’s Health Care.
“In the process of undergoing that decay, they emit different types of energy. What we do in nuclear medicine is, we inject patients with radiopharmaceuticals we’ve made, that have these isotopes in them, where they interact with the patients. They are emitting energy and the scanners we use are able to measure that energy.”
The world’s largest producer of medical isotopes – the 57-year old National Research Universal nuclear reactor at Atomic Energy of Canada’s Chalk River Laboratories – is scheduled to wind down operations by 2016 when its license expires. But there has been speculation that may be stretched to 2018.
Either way, it prompted the government to put out a call for proposals to hear from Canadian researchers.
Thanks to the team’s breakthrough technology, hospitals and companies will be able to retrofit current infrastructure with a ‘Made-in-Canada’ solution for producing Tc-99m. Major Canadian hospitals will use their own medical cyclotrons, such as the one located in London, to produce enough Tc-99m for their daily needs – in just one night.
Bringing together engineers, chemists, physicists, regulatory experts and clinicians, Kovacs said they had the idea to try to look at a theoretical paper, originally published in 1971, showing a nuclear reaction using a cyclotron to make the same sort of isotope.
“While it was just theoretical back then, we were able to develop a turn-key technology, like a bolt-on technology, for existing medical cyclotrons that are out there – and there are 260 of these machines in the world right now and growing – that we could use to make Tc-99m on the cyclotron.”
This innovation is safer than current technology as it eliminates the need to use weapons-grade radioactive uranium.
“It’s not a replacement technology. But for large centres, like London, yes, it could help,” Kovacs said. “Utilizing our state-of-the-art facilities, we have demonstrated that a reliable supply of cyclotron-produced Tc-99m for patients is now possible.”
With 5,500 nuclear imaging procedures per day in Canada, and 80,000 per day worldwide, Kovacs would love to stock the shelves. But there’s a catch.
“When we talk about radioactive isotopes, we’re always talking about what their half life is,” Kovacs said. “In the case of Tc-99m, it has a six-hour half life. So, if you start with 10 units of activity, after six hours, you have five. After another six hours, you go from five to two and a half, and so on. What this means is you can’t stockpile it.”
The technology has been developed to provide enough activity to supply the City of London, with the next step being a clinical trial through Health Canada. The research team is working with a Canadian start-up company to license, transfer and sell this technology around the world.
“We’re like a Lawson or Western brand aspirin, if you will,” Kovacs said. “It’s the same product, just made a different way. We have to show regulators it produces the same quality and make a case for its safety.”
