Interstitial radiation therapy
Radiation therapy: Radiation treatment given by placing radioactive material directly into the target, often a tumor.
For example, in treating prostate cancer, radioactive seeds are implanted in the prostate gland.
The seeds might be titanium-encased pellets containing the radioisotope iodine-125. Interstitial radiation therapy is also called seed implantation or brachytherapy (brachys being Greek for short).