Leaks in standard sealed teletherapy sources.

Abstract

Teletherapy sources encapsulated in the United States and Canada from 1954 to 1959 were generally of the standard, single capsule, sealed type. One feature of the standard capsule was believed to be its tight seal and its ability to maintain tais integrity. Late in 1958, a standard capsule source at the Oak Ridge Institute of Nuclear Studies (encapsulated 1.5 years earlier with Co/sup 60/ metal pellets) developed a leak. This leak resulted in from 30 to 100 mc of activity being released before it was detected. Subsequent investigation of other sealed sources in the United States revealed that thirteen of 200 standard teletherapy capsules had developed leaks. A review of the possible causes of leakage, and of the standard capsule design, fabrication, sealing and initial and subsequent leak testing, has resulted in recommended changes to reduce the probability of future capsule failures. The incidence of failures already encountered, however, has made apparent the importance of routine leak testing of encapsulated sources. (auth)