Review: Radiation Therapy
Two major types of radiation therapy are external beam radiation therapy and internal radiation therapy. External beam radiation therapy delivers radiation from a source at a distance from the body and is directed at the cancer site. Internal radiation therapy places radiation sources as close as possible to the tumor site. There are several sub-categories of internal radiation therapies based on the way radiation is placed inside the body: interstitial, intracavitary, intraluminal, and intravenously.
As an adjuvant therapy, radiation therapy is used to destroy microscopic cancer cells before and after other therapies. Lower doses of radiation are given to cancer patients for palliative purposes, most often given to bony metastases.