The full form of EBRT is External Beam Radiation Therapy

External beam radiation therapy comes from a machine that aims radiation at your cancer. It is a local treatment, which means it treats a specific part of your body. For example, if you have cancer in your lung, you will have radiation only to your chest, not to your whole body.

External beam radiation therapy is used to treat many types of cancer.

Radiation beams used in external radiation therapy come from three types of particles:

• Photons
• Protons
• Electrons

Most radiation therapy machines use photon beams. Photons are also used in x-rays, but x-rays use lower doses. Photon beams can reach tumors deep in the body. As they travel through the body, photon beams scatter little bits of radiation along their path. These beams do not stop once they reach the tumor but go into normal tissue past it.

Protons are particles with a positive charge. Like photon beams, proton beams can also reach tumors deep in the body. However, proton beams do not scatter radiation on their path through the body and they stop once they reach the tumor. Doctors think that proton beams might reduce the amount of normal tissue that is exposed to radiation. Clinical trials are underway to compare radiation therapy using proton beams with that using photons beams. Some cancer centers are using proton beams in radiation therapy, but the high cost and size of the machines are limiting their use.

Electrons are particles with a negative charge. Electron beams cannot travel very far through body tissues. Therefore, their use is limited to tumors on the skin or near the surface of the body.