External beam radiation therapy uses a high-energy x-ray machine called a linear accelerator (linac) to direct radiation to the tumor. The procedure lasts several minutes, and is typically repeated several times a week over several months. Types of external beam radiation treatments include:
- Three-dimensional conformal radiation therapy — a technique where the beams of radiation used in treatment are shaped to match the tumor.
- Intensity-modulated radiation therapy (IMRT) — a treatment method in which the intensity of the radiation can be changed during treatment. In conventional therapy, intensity is set for the entire treatment session.