Two groups - Johns's at the University of Saskatchewan, and another one in London, Ontario - designed and constructed external beam radiotherapy instruments using radioactive cobalt sources. The first treatment of a patient using the new source was carried out in London, Ontario, on 27 October 1951. In November 1951, the first Saskatoon patient, a 43-year-old mother of four, was treated for cervical cancer with a carefully calibrated dose of cobalt-60 radiation.