How it began
Two cobalt-60 units were finished in Canada within days of each other in the summer and fall of 1951. In Saskatoon the unit was designed by Harold Johns of the University of Saskatchewan and built by the machinist John MacKay, owner of Acme Machine and Electric, with graduate students including Sylvia Fedoruk. In London, Ontario, a unit made with the Eldorado company was installed at Victoria Hospital under Ivan Smith. A patient there was treated on October 27, 1951. Saskatoon treated its first patient in November.
Before it existed
Radiation therapy before 1951 relied on X-ray machines. The London hospital describes those earlier X-ray treatments as less targeted. The new machine let doctors treat tumors without damaging the surrounding skin, which the hospital calls a dramatic advance on what came before.
How it works
The radioactive cobalt-60 sat inside a lead cylinder cased in steel, hung from an overhead carriage. When the machine was switched on, radiation was directed through a treatment cone toward the patient's cancer. A device called a collimator set the size of the beam. Its lead bars moved in and out to make the beam larger or smaller to match the size of the tumor.
What lasted
The Saskatoon unit treated 6,728 patients before it was replaced in 1972, first by another cobalt machine and later by a linear accelerator. By the 1960s the cobalt-60 machine was standard equipment for radiation therapy around the world. The London hospital states that 35 million cancer patients worldwide benefited from cobalt-60 therapy in the decades that followed.
Where it stands today
Cobalt-60 machines are still in use in many lower income countries, where they remain a frontline treatment because they are cost effective and accessible. In wealthier hospitals they have largely given way to linear accelerators. The University of Saskatchewan marked the 60th anniversary of the technology with a museum exhibit in Saskatoon.
