What you can expect

External beam radiation therapy is usually conducted using a linear accelerator — a machine that directs high-energy beams of radiation into your body.

As you lie on a table, the linear accelerator moves around you to deliver radiation from several angles. The linear accelerator can be adjusted for your particular situation so that it delivers the precise dose of radiation your doctor has ordered.

You typically receive external beam radiation on an outpatient basis five days a week over a certain period of time. In most instances, treatments are usually spread out over several weeks to allow your healthy cells to recover in between radiation therapy sessions.

Expect each treatment session to last approximately 10 to 30 minutes. In some cases, a single treatment may be used to help relieve pain or other symptoms associated with more-advanced cancers.

During a treatment session, you'll lie down in the position determined during your radiation simulation session. You might be positioned with molds to hold you in place.

The linear accelerator machine may rotate around your body to reach the target from different directions. The machine makes a buzzing sound.

You'll lie still and breathe normally during the treatment, which takes only a few minutes. For some patients with lung or breast cancer, you might be asked to hold your breath while the machine delivers the treatment.

Your radiation therapy team stays nearby in a room with video and audio connections so that you can talk to each other. You should speak up if you feel uncomfortable, but you shouldn't feel any pain during your radiation therapy session.