External beam radiation therapy

External beam radiation therapy (EBRT) directs a beam of radiation from outside the body at cancerous tissues inside the body. It is a cancer treatment option that uses doses of radiation to destroy cancerous cells and shrink tumors.

What is external beam radiation therapy?

Using a special X-ray machine called a linear accelerator, EBRT delivers high-energy rays to tumors. The machine delivers radiation from any angle and shapes radiation beams to the contour of the tumor. The machine moves around the body without touching the patient, aiming radiation at the cancer. Some types of focused EBRT target a tumor with higher, more precise doses of radiation, while reducing damage to healthy tissue and nearby organs. As a result, EBRT may help reduce the risk of side effects associated with traditional radiation treatment.

What should I expect during my external beam radiation therapy?

Every patient’s experience during EBRT varies depending on the type of cancer, the size and location of the tumor and the type of therapy being used. But there are some general rules and expectations most patients should consider. For instance:

  • You may be asked to change into a hospital gown for your therapy, so wear clothes that are easy to remove. If a hospital gown is not necessary, you still may be asked to expose the area being treated, so you should wear clothes that are loose-fitting and comfortable. Do not wear jewelry.
  • A mold of the part of the body that is being treated may be required to help keep you still during treatment. If you are undergoing radiation therapy to the head and neck area, you may be fitted for a mesh mask designed to keep your head from moving during treatment.
  • Your skin may be marked with dots to identify the treatment area. These dots should remain on your skin for the duration of your treatment. If a mold or mask is required, it will also be marked.
  • You will need to remain still during your treatment, which will only take a few minutes.
  • EBRT is painless.
  • Patients do not become radioactive during or after EBRT treatments.

How long does external beam radiation therapy last?

EBRT treatments are typically outpatient procedures. The length of your treatment depends on many factors, including your type and stage of cancer. EBRT may be administered over a period of two to 10 weeks. Patients typically receive treatment once a day for five days in a row, generally Monday through Friday. The actual treatments last only a few minutes, but each session requires time to set up equipment and ensure the patient is in the correct position for treatment.

What are the different types of external beam radiation therapy?

Types of EBRT include:

3-D conformal radiation: This radiation therapy technique allows doctors to sculpt radiation beams to the shape of a tumor and is typically used on tumors with irregular shapes or that lie close to healthy tissues and organs, and may limit radiation exposure to surrounding healthy tissue. 3-D conformal radiation also allows doctors to view tumors in three dimensions. Based on these images, the radiation beams are delivered to the tumor from several angles.

Intensity-modulated radiation therapy (IMRT): Advanced software plans a precise dose of radiation, based on tumor size, shape and location. A computer-controlled device delivers the radiation in sculpted doses that match the 3-D geometrical shape of the tumor, including concave and complex shapes. The intensity of radiation beams can be adjusted across the treatment area in fractioned, separate beams as precision accuracy. This means higher doses of radiation can be delivered than traditional radiation therapy methods, while reducing exposure to healthy tissues. Because of its greater degree of accuracy, IMRT may be a treatment option for patients who have reached the maximum allowable dose of conventional radiation therapy and have a recurrent tumor in the treated area.

Image-guided radiation therapy (IGRT): Tumors can shift inside the body, because of breathing and other movement. Image guided radiation therapy (IGRT) may allow doctors to locate and track tumors at the time of treatment and deliver more precise radiation treatment. This technology also allows our radiation oncologists to make technical adjustments when a tumor moves outside of the planned treatment range. As a result, the radiation treatment is targeted to the tumor as much as possible, helping to limit radiation exposure to healthy tissue and reduce common radiation side effects.

TomoTherapy®: TomoTherapy combines a form of intensity modulated radiation therapy (IMRT), with the accuracy of computed tomography (CT) scanning technology, in one machine. With this technology, we sculpt radiation doses to match complex tumor shapes while avoiding sensitive structures. Using built-in CT scanning to confirm the shape and position of the tumor before each treatment, TomoTherapy may reduce radiation exposure to healthy tissues and organs. Before every treatment, scanning technology provides a 3D image of the treatment area, so the radiation beams can be targeted according to the size, shape and location of the tumor(s) on that specific day. The “slice therapy” approach treats tumors one layer at a time. Side effects are often reduced because less radiation reaches healthy tissues and organs. Many cancer patients who have reached their maximum tolerance dose of traditional radiation may be a candidate for TomoTherapy radiation.

Stereotactic radiation procedures: These procedures are designed to deliver, precise, highly concentrated doses of radiation to small areas in the body, allowing our radiation oncologists to reduce exposure to surrounding healthy tissue and limit the number of treatment sessions required. We use two types of stereotactic procedures: stereotactic radiosurgery and stereotactic body radiation therapy.

What types of cancer are treated with EBRT?

External beam radiation therapy is used to treat many cancer types, including some of the most common cancers:

What side effects are caused by external beam radiation therapy?

Standard radiation therapy treatments may damage some healthy cells, often causing unpleasant side effects. The side effects of EBRT may vary depending on the length of treatment and the part of the body being treated. Side effects may include:

  • Skin changes
  • Fatigue
  • Nausea
  • Hair loss
  • Swelling
  • Difficulty swallowing
  • Tenderness and inflammation

At Cancer Treatment Centers of America® (CTCA), we understand that many patients do not realize how the side effects of cancer treatments may affect them. That’s why we take the time to educate patients—before, during and after treatment—about how their bodies will respond and provide an array of supportive care therapies designed to help them maintain their strength, stamina and quality of life. Evidence-informed therapies that may help manage the side effects of EBRT include: