Getting External Beam Radiation Therapy
External radiation is the most common type of radiation therapy used for cancer treatment. You might also hear it called external beam radiation.
For this type of treatment, radiation (high-energy rays or particles) is aimed at the tumor from a machine outside your body. The machine focuses the radiation beam on the exact location of the tumor. It usually happens during outpatient visits to a hospital or treatment center.
Learn more about the types of external radiation therapy and what to expect during and after treatment.
- Beams used in external radiation therapy
- Types of external radiation therapy
- Photon beam radiation therapy
- Particle beam radiation therapy
- How long does external radiation treatment take?
- What happens during each treatment visit?
- Will I be radioactive during or after external radiation treatment?
- Learn more
Beams used in external radiation therapy
External radiation therapy is usually given as photon (x-ray) beams. Less often, particle beams (proton, neutron) or electron beams are used.
These beams are delivered very carefully. Most of the radiation reaches the cancer, and the healthy tissues in your body are damaged as little as possible. The beams are invisible and painless when they pass through your skin to the cancer.
Photon beams are the same type of radiation used during an x-ray, but the beams are much stronger. They can travel deep into your body to reach the tumor, but they can also damage healthy tissue around the tumor.
A machine called a linear accelerator delivers the photon beams. The radiation is released from the machine as a wave of energy.
Particle beams are made up of separate units of energy, such as protons or neutrons. They can travel deep into your body like photon beams, but their energy is only released at a certain distance.
This type of treatment can often deliver more radiation to the tumor while limiting damage to nearby normal tissues.
Special machines called particle accelerators (cyclotron or synchrotron) deliver the particle beams. The radiation is released from the machine as a stream of high-energy particles.
Electron beams are also separate units of energy. They can act like particle beams or be changed into photon beam radiation. Electron beams can be given from