Harold Elford Johns | The Canadian Encyclopedia


Harold Elford Johns

Harold Elford Johns, OCFRSC, physicist, educator (born 4 July 1915 in Chengdu [Chengtu], West China; died 23 August 1998 in Kingston, ON). Harold Johns is recognized for his contributions to medical physics and for the development of cobalt-60 therapy units, used in cancer treatment. (See also Canadian Contributions to Medicine.)

Harold Elford Johns
Harold Elford Johns with a high-energy radiation unit, 27 June 1980.
(Photo by Boris Spremo/Toronto Star via Getty Images)


Educated at McMaster University and the University of Toronto, Harold Johns devoted his career to the application of physics to medicine and biology and to training students with similar interests. He is best known for his development at the University of Saskatchewan of cobalt-60 therapy units which revolutionized the radiation treatment of cancer worldwide, and for his pioneering efforts in a variety of areas of medical physics and photochemistry.

Did you know?

In November 1951, Harold Johns and his team used cobalt-60 radiation therapy to treat a cancer patient. (See also Canadian Contributions to Medicine; Sylvia Olga Fedoruk.)

Cobalt Therapy

His work was at all times characterized by the application of imagination and experimental skill backed by theoretical rigour to the solution of major problems, largely related to cancer diagnosis and treatment. An inspiring and enthusiastic teacher and lecturer, he was the initiator of Canada's first department of medical biophysics at the University of Toronto and gained international recognition for his research and educational efforts. He also served as chairman of the Healing Arts Radiation Committee (1981-82).


Harold Johns was the author of numerous scientific papers and the book, The Physics of Radiology (4th ed., 1983).

Honours and Awards

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