External Radiation Therapy

This information is useful for children, adults, and older adults
A doctor speaks to a patient about External Radiation Therapy.

For a person with cancer, radiation therapy is often part of the treatment plan. If you or a loved one needs radiation therapy for cancer treatment, a radiation oncologist will decide whether external or internal beam radiation therapy is the right option.

External radiation therapy, also called external-beam therapy (EBT), refers to a treatment that uses beams of radiation delivered from a machine outside the body to precisely target a tumor. In contrast, internal-beam radiation—also called brachytherapy—uses radioactive implants, such as seed implants, placed inside the body near a tumor to deliver radiation locally.

External radiation therapy is used to treat a wide variety of cancers, including skin lymphoma, breast, colorectal, esophageal, head and neck, lung, brain tumor and prostate cancers. If you are scheduled to have external beam radiation therapy, you might wonder what to expect and want to learn more about what’s involved in the treatment.

“The radiation used in external beam radiation therapy can come from a variety of sources,” says Yale Medicine’s Lynn Wilson, MD, vice chair and clinical director of the Department of Therapeutic Radiology. “Your doctor may choose to use X-rays, an electron beam or cobalt-60 gamma rays.”

At Yale Medicine, we have highly specialized radiation oncologists who focus on treating one kind of cancer. They work alongside highly trained physicists to ensure radiation therapy is delivered precisely where it will be most effective in treating cancer.