It was October 27, 1951. The world's first cancer treatment with Cobalt-60 radiation took place at Victoria Hospital in London, Ontario.

First clinical Betatron application by Konrad Gund in Germany, 1942

At that time radiation emitting equipment, such as X-ray machines were primarily used in the diagnostic department of a hospital. Dermatology departments were also experimenting with X-ray at higher energy levels to treat superficial abnormalities. The use of these superficial X-ray machines facilitated research toward machines which could treat deeper depths within the human body. Examples of devices that could output higher energies were the Betatron and Linear accelerator. A strong argument was made in the late 1940's to use Cobalt-60 as a radiation source as an expanding nuclear industry in Canada was producing various radioisotopes for commercial use. The Cobalt machine also became more available to hospitals without university affiliations as a result of its simplicity in design, insignificant electrical and HVAC requirements, and the availability of Physicists and other technical personnel that could support them.

Superficial X-ray machine used in Mobile Army Surgical Hospitals. (M.A.S.H.)

Cobalt-60 radiation treatment machine used for the first time on a patient in London, Ontario, Canada, at the Victoria Hospital, October 27, 1951.

Designing a Cobalt-60 treatment room was also relatively simple when we compare it to an X-ray room, because its infrastructure requirements were insignificant. The major difference was the extra shielding requirements in the walls and door as X-ray room doors could not withstand a direct Cobalt-60 radiation beam. Electric or hydraulic operated doors were often prohibitive because of the experimental nature of these first radiation treatment machines and the limited research funds available. Therefore, it was often decided that a Cobalt radiation treatment room would require a small maze to protect the door from direct radiation exposure. A well designed maze allowed the use of a wooden door with a thin sheet of lead between the two wooden panels. This was very similar to the doors already used in the X-ray and Dermatology departments. The room also required a thick leaded glass window to allow the operator to monitor the patient while being treated. This lead window technology was also developed for the X-ray industry, but obviously the glass used in a Cobalt room had to be significantly thicker to protect the operator from harmful radiation.

Cobalt-60 radiation treatment room with a small maze.

Heavy steel door for a high energy radiation treatment room.

Leaded windows were eventually replaced by CCTV cameras when more powerful radiation treatment machines were utilized. The first cameras generated black and white images, but when color cameras became more compact, reliable and affordable, black and white cameras were phased out. As with many technologies, radiation treatment machines were becoming more powerful. This necessitated the use of heavier lead lined or steel doors. Doors became so heavy that radiation treatment machine operators could no longer close the doors manually. This led to using hydraulic or electric drive systems to operate the door. Some cancer treatment facilities went with a different approach. They felt that longer mazes were the solution, thereby avoiding heavy doors, finger pinching and serious mechanical or electrical failures. The energy of the radiation treatment machines increased even more and eventually exceeded the 10MV. For the first time radiation treatment machines were producing both X-ray and neutron radiation. Neutrons behaved completely different compared to an X-ray beam and resulted in the use of massive doors for rooms with no or short mazes or a combination of an X-ray and a Neutron door with complex interlock systems to prevent accidents due to human error or safety equipment failure. Again some cancer organizations decided that complexity could be avoided by designing rooms with a longer maze having neutron absorbent materials in its walls. The inherent safety of a longer maze often allowed a light wooden door or a maze with no door at all. The majority of cancer centres in Canada have doorless entry systems for their radiation treatment rooms. This avoids the many safety and maintenance concerns related to heavy doors. The president of ISTAVA Inc has been involved for the last 15 years in the design and installation of doorless entry systems in Canada. As an active member of a provincial design team, he has advocated doorless and treatment room universality. The sophistication of the doorless interlock system has grown from a simple relay circuit with warning lights and a couple of sensors to a dual computer system with safety redundancies, self diagnostic programs, LCD displays, interfaces to 3rd party supplied devices and the ability to monitor adjacent unshielded rooms.

Canadian postal stamp celebrating 50 years Cobalt treatments.