Closely related to SRS, stereotactic radiation therapy (SRT) consists of multiple or “fractionated” doses of focused radiation. Treatment takes place over the course of several days or even weeks of treatment delivery sessions.
SRT is commonly used when a tumor is near an anatomical structure that is especially sensitive to high doses of radiation. In any radiation therapy technique, a small area of healthy cells around the tumor, known as the margin, receives some degree of radiation.
Each time a cell receives radiation, the cell is damaged. Healthy cells, however, are far better equipped to repair this damage than the abnormal tissue of tumor cells. The SRT treatment uses less radiation at any given time, and is spread out over a longer duration to allow these healthy cells time to repair while delivering adequate doses of radiation to destroy tumor cells.