Cobalt-60 at 60 Exhibit

The Cancer Bomb exhibit project - Cobalt-60 at 60 - celebrates the 60-year legacy of the cobalt-60 cancer therapy technology. The project is a partnership of the Saskatoon Western Development Museum and the University of Saskatchewan Research Communications, with sponsorship from the Potash Corp.

The exhibit was officially opened on Dec. 4, 2011 with dignitaries from the WDM, the U of S, and the Saskatchewan government. The exhibit is located in the East Wing of the Saskatoon WDM, in the area leading into the Car Gallery, the same area occupied by the Wind Exhibit.

Text by Joan Champ, Executive-Director of the Western Development Museum, with research support from University of Saskatchewan Archives

The Cancer Bomb Exhibit

View the exhibition at the Western Development Museum.

A New Weapon in the War Against Cancer

No, it didn’t bomb countries. In 1951, one of the world’s first cobalt-60 “bombs” for treating cancer was built in Saskatoon by a dedicated team of scientists and one excellent machinist. Since then, thousands of Canadian cobalt-60 units have provided radiation treatment for millions of cancer patients around the world. This is very much a Saskatchewan – and a Saskatoon – story.

Sylvia Fedoruk

Sylvia Fedoruk, a graduate student in physics, moves the rotating head of the Cobalt-60 unit into position with the aid of a push-button control.

Credit: University of Saskatchewan Archives, Harold E. Johns Collection

Medical Pioneers

Between 1924 and 1941, the rate of cancer deaths more than doubled in Saskatchewan. Something had to be done. In 1944, the new government of Tommy Douglas implemented a North American “first” – free cancer treatment to anyone who had lived in Saskatchewan for at least three months. Then, in 1949, Douglas personally gave the University of Saskatchewan scientists the “green light” to proceed with the development of the cobalt bomb. Douglas’ confidence in the scientists is part of the reason that Saskatchewan is home to the world’s first successful radiation treatment for cancer with the cobalt-60 unit.

Premier Tommy Douglas

Premier Tommy Douglas

Credit: Saskatchewan Archives Board, Melville-Ness Collection, S-MN-B3471

Nurse Anne Chudy

Nurse Anne Chudy and patient with the betatron, used for high voltage radiation treatment of cancer, University of Saskatchewan, Saskatoon, c. 1949.

Credit: Saskatchewan Archives Board, R-A5236(2)

The Cobalt Race is On!

There were actually two cobalt bombs in development during the summer and fall of 1951 – one in Saskatoon and the other in London, Ontario. Each had a different design by a different designer, and both were completed and functioning within days of each other. The Saskatoon team was the first to successfully treat a patient with an accurately calibrated dose of cobalt-60 radiation.

Dr. Harold Johns and John MacKay

Dr. Harold Johns and John MacKay transfer cobalt-60 into treatment unit, University Hospital, Saskatoon, 1951.

Credit: Courtesy Dr. Sylvia Fedoruk

The Cobalt-60 Unit

This is the original Cobalt-60 Beam Therapy Unit, known as the cobalt bomb, which was designed, built and operated in Saskatoon. Unlike the atomic bomb of the Cold War era, this bomb helped rather than harmed people. Radioactive cobalt from the unit attacked tumours that lay deep within the

body, thus bringing more cancers within reach of treatment. 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. She lived another 47 years. The cure rate for cervical cancer soon went from 25 per cent to 75 per cent.

Dr. Harold Johns, John MacKay, and Dr. Sandy Watson

Dr. Harold Johns, University of Saskatchewan; John MacKay, Acme Machine and Electric; and Dr. Sandy Watson, Director of Cancer Services, Saskatchewan Cancer Commission, with the original treatment cone on the cobalt-60 unit.

Credit: Courtesy Dr. Sylvia Fedoruk

How it Worked

Radioactive cobalt-60 was housed inside the steel-encased lead cylinder that was suspended from an overhead carriage. When the unit was turned on, radiation was

directed through the treatment cone towards the patient’s cancer. The size of the radiation beam is defined by a “collimator” designed by John MacKay and Dr. Harold Johns. The collimator’s lead bars moved in and out, making the radiation beam bigger or smaller, depending on the size of the patient’s tumour. John MacKay’s small Saskatoon shop manufactured over 100 of these collimators for world-wide distribution through the Picker X-Ray Corporation.

Drawing of the cobalt-60 unit

Drawing of the cobalt-60 unit before the collimator was installed in the treatment cone.

Credit: University of Saskatchewan, Harold E. Johns Collection, MG 372

Drawing of the collimator

Drawing of the collimator for the cobalt-60 unit’s treatment cone.

Credit: University of Saskatchewan, Harold E. Johns Collection, MG 372

The Bomb Builders

Canada’s first full-time cancer physicist, Dr. Harold Johns, and his colleagues at the University of Saskatchewan’s Department of Physics, led the world in the development of high-technology cancer treatment. The Saskatoon team pioneered the world’s first betatron accelerator for treating cancer in

1948-49. Their greatest achievement, however, was the cobalt bomb. It was designed by Johns and built by Saskatoon machinist John MacKay, owner of the Acme Machine and Electric Co. Dr. Johns’ graduate students, including Sylvia Fedoruk, Edward Epp, Douglas Cormack, and Lloyd Bates, assisted with the design and calibration of the machine.

“…John MacKay’s little shop on Avenue A [now Idylwyld Drive] has become a miniature factory of these miracles of the atomic age.”
- Saskatoon StarPhoenix, 1952

Sylvia Fedoruk and Ed Epp

Physics graduate students Sylvia Fedoruk and Ed Epp obtaining radiation depth-dose measurements in a tank of water with the cobalt-60 unit prior to treating the first patient, Saskatoon, c. 1951.

University of Saskatchewan Archives, H.E. Johns fonds, MG372

John A. MacKay

John A. MacKay with a cobalt unit built in his Saskatoon shop, c. 1955.

Credit: Courtesy of Dr. Alexander (Sandy) MacKay

Saskatchewan Leads the Way

Saskatoon’s cobalt unit treated 6,728 patients until it was replaced in 1972, first by another cobalt radiotherapy machine, and later by a linear accelerator. By the 1960s, the cobalt-60 machine was standard equipment for radiation therapy world-wide.

These machines are still in use in many Third World countries that previously did not have the necessary resources for good radiation therapy

Building on the achievements of the 1940s and 1950s, Saskatchewan’s cancer program has grown to become one of the best in the world. Today, the University of Saskatchewan is a centre of excellence for nuclear medicine and research in Canada.

Cobalt-60 radiation therapy treatment

Cobalt-60 radiation therapy treatment, University Hospital, Saskatoon, 1951.

Credit: Saskatchewan Archives Board, R-A11320(4)


““Though born of war-time nuclear research, the cobalt bomb was in practice a ploughshare rather than a sword…. With its flair for trend-setting performance in medicine, Saskatchewan had led the way.”
- C. Stuart Houston and Sylvia O. Fedoruk, in A New Kind of Ray, 1995