Brachytherapy is a treatment utilizing small radioactive sources. Typical radioactive sources include Cs-137, Ir-192, I-125, and Pd-109. Brachytherapy can be intracavity or interstitial.
Intracavity brachytherapy utilizes externally loaded applicators which are inserted into the body via a body cavity. This types of implants are usually temporary and are removed after a few days.
Interstitial implants are both temporary and permanent. For permanent implants, the radioactive sources are left in the body indefinately where they deposit all of their radiation.