Born: July 4, 1915, Chengtu, China
Died: August 23, 1998
Education: B.A. - McMaster University; Ph.D - University of Toronto
Category: Imaging, Radiation Physics

Harold Elford Johns came to Canada to make his worldwide impact on medicine. He obtained his B.A. from McMaster University and his M.A. and Ph.D. from the University of Toronto. Dr. Johns took great strides in the fight against cancer. He invented and developed the Cobalt-60 machine which had an immediate impact on the cancer survival rate. Prior to the Cobalt-60, cancer therapy through radiation could only get to superficial tumors, but now this treatment could treat tumors that were deep-set and difficult to access. The machine was a major technological development, and the method was the start of the development of cobalt therapy for the treatment of cancer and is still a mainstay for cancer treatment in many third world countries.

Johns is considered to be influential in the early development of CT scanners and the definition of mammographic imaging. He also did significant work in showing the DNA damage in cells exposed to ultraviolet rays. Johns' book, The Physics of Radiology , is considered to be the primary work in medical physics, the field of Canadian medicine that he founded.

Many awards and much recognition have been accorded to Johns' career. Johns is an Officer of the Order of Canada, a recipient of the Queen's Jubilee Medal and was the first to receive the Medal of Honour from the Canadian Medical Association, which is the highest honour that the Association can bestow on a person who is not a member of the medical profession. Dr. Harold Johns passed away August 23, 1998.