Minke Whales to Honey Bees

Novel Applications of Low Energy Accelerators

March 19, 2013

Written by: Mark Broeders, Program Officer, Accelerators and Class II Facilities

Before 2011, the responsibility for regulating electron accelerators with energies less than 10 mega or million electron volts (MV) was somewhat unclear. At that time, the CNSC made a policy decision to regulate accelerators operating above 10 MV, while the provinces took on the responsibility for the low energy accelerators.

Most accelerators were typically designed to operate above 10 MV. Over the last decade, however, new technology and applications have dramatically increased the number of low energy linear accelerators (linacs), a type of particle accelerator used to produce X-rays, in use in Canada. But while some provinces applied the same regulatory standards as the CNSC, others did not. In October 2011, the CNSC made a policy decision to include all electron accelerators with beam energies greater than 1 MV under its oversight.

Mission accomplished

By December 31, 2013, all operational low energy electron accelerators were certified and licensed by the CNSC. In the end, 53 additional accelerators were impacted: 38 in the medical sector, 12 in the industrial sector and 3 in the research/academic sector. Many industrial and research licensees were first-time Class II licensees and therefore required significant support from our staff in this process.

The provincial authorities have cooperated with this policy change. For instance, the Ontario regulator invited the CNSC to a joint inspection following an unusually high dose reading at a facility that the CNSC had not yet licensed (the dose was a non-personal exposure).

Novel linac applications

While licensing this equipment, we've encountered some interesting linac applications. One research company is using a linac as a high-energy CT scanner. One of its more interesting projects was to scan a Minke whale foetus to determine the cause of death (it was a broken jaw).

Industrial applications include mobile cargo screening, irradiation of topaz and other gem stones to improve their colour and irradiation of beehive frames to kill the Nosema ceranae parasite that can destroy bee colonies.

The medical sector provided some additional regulatory challenges with new technology that married robotic technology from the automotive industry with an accelerator. Because the linac accelerator (e.g., CyberKnife) can point virtually anywhere on a wall, verification of adequacy of shielding design was made a little more complicated than for traditional medical accelerators.