12.1 - Properties Of Sealed Sources

A sealed source is a radioactive compound that is:

  • Sealed within an impermeable container (eg. 125I)
  • A solid material that is unable to be dispersed (eg. 192Ir)

Specific Sealed Sources

Uncommon and Historical Sources


Radium-226 was the first source used in brachytherapy. It has a complex decay chain, including gaseous 222Rn, which presents a health hazard. It has fallen out of favour due to safer sources such as 192Ir and 137Cs.


Cobalt-60, perhaps more famous for use in external beam teletherapy, was also used in low dose rate form for intracavity and interstitial brachytherapy, similar to iridium, caesium and radium.