BORN: Chengtu, West China • 4 July 1915
THE ODDS WERE LONG ON HAROLD JOHNS EVER having much to do with Canada, let alone becoming an influential Canadian. Born to missionary parents from Toronto in the Szechuan province of West China in 1915, Johns spent his formative years learning to speak Chinese.
His parents taught and preached at a local university, and were content to continue doing so. Mounting political and social turmoil in China, however, forced the family to return to Canada just in time for Johns to attend high school. He ended up at McMaster University, then in Toronto, where he earned a doctorate in physics in 1939.
A postdoctoral fellowship at Cambridge beckoned, but the war in Europe dashed these plans and Johns settled for a teaching position at the University of Alberta. After the war Johns was appointed assistant professor of physics at the University of Saskatchewan.
Saskatoon was a long way from anywhere in 1945—especially for a young scientist keen on working on a pathbreaking project. Yet circumstances were auspicious for a medical breakthrough. The Saskatchewan government, perennially Canada’s leader in progressive reform, had established North America’s first government- sponsored cancer clinic in 1931.
By the 1940s the province was something of an authority on the treatment of cancerous tumours with radiation beams. Doctors enjoyed limited success with some cancers, but there were continuing prob¬ lems associated with radiation therapy.
Not the least of these was the enormous expense and potential danger of radium, the radioactive element used to create the healing beam. Soon after arriving in Saskatchewan, Johns persuaded his superiors to fund his research on finding another source of radia¬ tion for the treatment of cancer.
Premier Tommy Douglas personally approved the expensive research and, improbably, Johns was on his way to making a significant discovery.The key to the puzzle was cobalt-60. The world’s source of this radioactive element was a nuclear reactor at Chalk River, Ontario, at a facility created by the Canadian govern¬ ment for Second World War nuclear research.
Johns convinced scientists there, fresh from a top-secret role in the Manhattan Project, to prepare small quantities of cobalt-60 for his experiments. At the same time, he set to work designing and building a treatment machine that could exploit cobalt-60.
When it was finished, the results were spectacular: Johns’ machine was infinitely cheaper and vastly more powerful than anything else in existence. The media, which inevitably associ¬ ated any sort of radiation research with Hiroshima, dubbed the new invention the “cobalt bomb.” And the way cancer patients were treated was vastly improved almost overnight.
Johns was still a young man after the first cancer patient was treated with the new cobalt-60 machine in 1951. Most of his scientific career lay ahead of him. At first he concentrated on experiments designed to calculate the appropriate doses of radiation to be delivered from his machine for specific kinds of cancer.
Through a vast body of published research, he and his growing cadre of graduate students made Saskatchewan a leading centre for advances related to radiation doses. He continued his internationally recognized work in Toronto at Princess Margaret Hospital and the Ontario Cancer Institute in 1956, and in 1958 created the Graduate Department in Medical Biophysics at the University of Toronto.
A perma¬ nent place in the university now was established for the recruitment of physicists to attack the problems associated with treating cancer with radiation.Today more than 3000 “cobalt bomb” machines are used to treat cancer in over seventy countries. Perhaps 7 million patients have been treated with Johns’ brainchild. Most of these machines are Canadian-built.
But even with improved techniques, Johns’ invention is not a miracle cure: doctors and scientists around the world continue to be frustrated by their inability to find a permanent cure for the killer disease.
Yet in combination with surgery and drug treatment, cobalt- 60 radiotherapy bought time and, in millions of cases, new life for patients around the world. It is that, combined with an international legacy of research and discovery, which makes this Chinese-born Canadian among the most influen¬ tial scientists his country has produced.