Tuesday, 12 June 2012

Medical isotopes – the Coming crisis in supplies for Technetium-99

A good read: Medical isotopes – the Coming crisis in supplies for Technetium-99: http://www.kidela.com/columns/medical-isotopes-the-coming-crisis-in-supplies-for-technetium-99/ ..."The 2009 shutdown, after a leak of heavy water from the reactor, lasted 15 months and caused severe disruption to supplies of moly-99, especially in North America. Four other specialized reactors around the world – in the Netherlands, Belgium, France and South Africa – tried to pick up the slack, but the result of the Chalk River shutdown was that moly-99 became much harder to get, as well as much more expensive.
Without regular supplies of moly-99 and the tech-99 it produced, many hospitals were forced to reschedule important scans for patients, often for several weeks. Some hospitals turned to alternative isotopes that are not as effective for scanning or potentially more harmful for patients.
For some patients, a positron-emission tomography (PET) scan could be used in place of a SPECT scan using tech-99. But PET scanners are much more expensive than the SPECT scanners, and are not available at many hospitals.
The Chalk River reactor restarted late in 2010, and hospital supplies of moly-99 have returned to normal – for now. But the reactor is now 54 years old, and it has already suffered one radiation leak. An attempt to extend its operating life beyond its scheduled shutdown in 2016 is likely to prove politically difficult.
So far, plans to find effective alternatives to the Chalk River reactor have come too little. In 1996, Canada commissioned two new “Maple” reactors to take over the production of medical isotopes from Chalk River. The new reactors were abandoned in 2008 as unsafe, but their construction discouraged potential competitors.
In 2010, the US Department of Energy commissioned General Electric to investigate a new method of producing medical isotopes using commercial power reactors, which are fueled by low-enriched uranium instead of the highly-enriched uranium used at Chalk River. The method showed early promise, but that project has also foundered: GE decided the process was not financially competitive, and shelved the project. [2]
But another Canadian idea has shown some positive results. After the Maple reactors were abandoned, the Canadian government invested $35-million CAN to research the production of medical isotopes using cyclotrons – small particle accelerators already used in a dozen hospitals in Canada and more than 100 hospitals in the United States.[3].
The cyclotron process uses an accelerated proton beam to bombard a sample of molybdenum-100, stripping away neutrons from the atomic nuclei of the sample to create technetium-99m directly. Researchers at the University of Sherbrooke, one of four teams investigating the new process, say a single cyclotron could produce 800 doses of tech-99 a day, enough to serve a population of around six million people.[4]"

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