Teletherapy Source (ca. 1950s)

Teletherapy Source (ca. 1950s)

The above is a source capsule of the type that was used in medical teletherapy units. The gamma rays emitted by the source were used to treat cancer. The radioactive source material, over 1000 curies of Co-60 or Cs-137, was contained in a doubly encapsulated stainless steel cylinder approximately one inch in diameter (shown in the lower right hand corner of the photograph on the right). The rest of the capsule (approximately two inches in diameter) consisted of a tungsten alloy housing threaded to fit into the teletherapy unit. The top of the housing contained an opening through which the stainless steel source container could be seen.

Pre-1955 cobalt 60 teletherapy source capsules came in all sorts of sizes and shapes. This made replacing the old sources a complex and time consuming process. In October of 1953, representatives of 14 X-ray equipment manufacturers met with representatives of the U.S. Atomic Energy Commission, Atomic Energy of Canada Limited, Oak Ridge National Laboratory and the Oak Ridge Institute of Nuclear Studies (ORINS) at the ORINS Medical Division to discuss the issue. As a result of this meeting, the source capsule shown here was developed and adopted as the standard configuration. 

This particular example came from Oak Ridge Associated Universities, which used to be known as the Oak Ridge Institute for Nuclear Studies. As such, it might date from the period when the design was being standardized.


  • Marshall Brucer. A Standard Cobalt 60 Teletherapy Source Capsule. British Journal of Radiology. XXVII, No. 319. July 1954.
  • Marshall Brucer. Standardized Co-60 Source Capsule for Teletherapy. Nucleonics June 1954, page 58-59.