Inspired by the suggestion that cobalt-60 might be a better source of radiation for cancer therapy, Johns applied to the National Research Council at Chalk River for a sample of cobalt-60. With one of the three samples produced at Chalk River in 1951, Dr. Johns designed a unit capable of safely delivering the radiation. Having been carefully tested and calibrated for three months, Dr. Johns’ unit was first used to treat a patient on 8 November 1951.

His textbook ""The Physics of Radiology,"" first published over a half-century ago, is used by radiation specialists throughout the world to this day, and ""cobalt-60"" is a treatment still widely used for therapeutic purposes. It provides a reliable and cost-effective source of radiant energy in the battle against cancer.
Canadian Heritage Information Network
Canada Museum of Science and Technology, Musée de la civilisation, Stewart Museum, Canadian Medical Hall of Fame, Museum of Health Care at Kingston, University Health Network Artifact Collection, University of Toronto Museum of Scientific Instruments, University of Toronto Museum Studies Program

© CHIN 2001

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