Internal Radiation Therapy

Internal Radiation Therapy

Internal radiation therapy refers to treatments in which a radioactive substance is placed inside your body so it can release radiation from within. Often the substance is a small implant, which may be left in for only minutes or for days. It may also be left in permanently. Internal radiation therapy can be taken in pill form by mouth or as a fluid that you get intravenously.


Brachytherapy is radiation therapy that’s delivered by implanting a small radioactive source—such as a seed, pellet, wire, needle, or capsule—inside your body. A doctor places the source next to or inside the tumor using a tube-like applicator. Depending on your specific situation, you might need a high-dose radiation source that’s inserted for a short time (and then removed) on several occasions. Or you might need a low-dose radiation source that’s inserted once and left for weeks, for months, or permanently.

Systemic Radiation Therapy

Radioactive medicines can be taken by mouth or injected in a vein. These medicines travel throughout the body, collect where there’s cancer, and give off radiation to kill cancer cells. One example is radioactive iodine therapy, used to treat thyroid cancer.