The world needs accelerator-based production of Tc-99m
Technetium-99m (Tc-99m) is the world's most highly used medical isotope and is the critical component driving over 76,000 imaging procedures per day.
Historically, Tc-99m has been produced in a select number of nuclear reactors around the world, including Canada's Chalk River Reactor. These reactors produce large quantities of molybdenum-99 (Mo-99), which undergo radioactive decay to form Tc-99m within special generators as they are shipped and stored at local hospitals.
| Sources of Tc-99m from conventional nuclear reactors, courtesy the Globe & Mail. |
Only a few reactors around the globe are capable of producing Mo-99 at an appreciable quantity, and many of these reactors are aging and require more frequent shutdowns for maintenance and repairs. Over the next few years, irradiation and processing capacities of medical isotopes are forecasted to drop as demand rises, if no new facilities or technologies are brought into the market.
The graphs below are based on the current fleet of irradiators and processors, and are taken from the Nuclear Energy Agency’s (NEA) 2014 report The Supply of Medical Radioisotopes: Medical Isotope Supply in the Future: Production Capacity and Demand Forecast for the Mo-99/Tc-99m Market, 2015-2020. It should also be noted that the timelines for some current irradiators include an assumption that operating license extensions will be granted by the relevant authorities.
NEA, April 2014. ORC = Outage Reserve Capacity
A shortage of medical isotopes arose in 2009 when Canada’s National Research Universal (NRU) reactor at Chalk River Laboratories was shut down unexpectedly on May 14, 2009, following the discovery of a leak of heavy water. Another shortage occurred in 2011 following a shutdown of the NRU for regular maintenance.
For many years, Canada’s NRU reactor supplied approximately one third of the world’s demand of Mo-99 for Mo-99/Tc-99m generators used in hospitals for diagnostic nuclear medicine. The NRU shutdowns in 2009 and 2011 created major problems in supplying Tc-99m to nuclear medicine sites in many countries, including Canada, and illustrated the existing system’s single point of failure vulnerability. A permanent shutdown of the NRU reactor will create a major isotope shortage both in Canada and globally. As the NRU is winding down, the Government of Canada is supporting several research projects geared towards finding a solution for alternative production strategies to meet the nation’s isotope needs.
Work is under way to demonstrate the production of the medical isotope Tc-99m using particle accelerators such as cyclotrons.