Tommy Douglas in 1944 Harold Johns takes a tour of North American radiological centres. The phone rang at all hours of the day and night, so we were very aware that something very important was taking place.'' - Gwen Greenstock, daughter of Harold Johns, inventor of the cobalt-60 unit in a 1994 CBC interview 1946 There were visitors from all over the world. 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.” – Canadian Medical Hall of Fame, Citation for posthumous induction of Dr. He invented and developed the Cobalt-60 machine which had an immediate impact on the cancer survival rate. Johns took great strides in the fight against cancer. Harold Johns jointly appointed to the USask physics department and the Saskatchewan Cancer Commission supervised radium and X-ray therapy equipment for Saskatchewan’s two cancer clinics, becoming Canada’s “first full-time cancer physicist.” He came to be known as “the father of medical physics in Canada.” Co-60 absorbed by the liver, kidneys, or bone tissue can cause cancer because of exposure to the gamma radiation.Harold Johns speaking Most Co-60 that is ingested is excreted in the feces however, a small amount is absorbed by the liver, kidneys, and bones. Radionuclides, such as cobalt-60, that are used in industry or medical treatment are encased in shielded metal containers or housings, and are referred to as radiation 'sources.' The shielding keeps operators from being exposed to the strong radiation.īecause it decays by gamma radiation, external exposure to large sources of Co-60 can cause skin burns, acute radiation sickness, or death. This process is sometimes called "cold pasteurization."Ĭobalt-60 is also used for industrial radiography, a process similar to an x-ray, to detect structural flaws in metal parts. After the radiation ceases, the product is not left radioactive. The powerful gamma rays kill bacteria and other pathogens, without damaging the product. ![]() Large sources of cobalt-60 are increasingly used for sterilization of spices and certain foods. In particular, cobalt has can be magnetized similar to iron.Ĭobalt-60 is used in many common industrial applications, such as in leveling devices and thickness gauges, and in radiotherapy in hospitals. It is solid under normal conditions and is generally similar to iron and nickel in its properties. It is also produced as a by-product of nuclear reactor operations, when structural materials, such as steel, are exposed to neutron radiation.Ĭobalt (including cobalt-60) is a hard, brittle, gray metal with a bluish tint. The radionuclide, cobalt-60, is produced for commercial use in linear accelerators. Nonradioactive cobalt occurs naturally in various minerals, and has been used for thousands of years to impart blue color to ceramic and glass. Seaborg and John Livingood at the University of California - Berkeley in the late 1930's. Radioactive cobalt-60 was discovered by Glenn T. Previously, people thought that bismuth, which occurs in nature with cobalt, was the cause. In 1735, a Swedish scientist, George Brandt, demonstrated that a blue color common in colored glass was caused by a new element, cobalt. ![]() The most common radioactive isotope of cobalt is cobalt-60. ![]() Cobalt (chemical symbol Co) is a metal that may be stable (nonradioactive, as found in nature), or unstable (radioactive, man-made).
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