External Beam Radiation Therapy

What is external beam radiation therapy?

External beam radiation therapy (EBRT) is a commonly used cancer treatment. Radiation is sent from a machine directed at the part of the body where cancer is present. The doctor who oversees the treatment will decide on the type of machine used.

External beam therapy uses a type of radiation called ionizing radiation. This destroys the cancer cells, but it can also harm healthy cells.

To give healthy cells time to heal, you will get small doses of radiation at each treatment session. This helps protect the healthy tissue around the diseased area.

This type of radiation comes from a type of large X-ray machine from outside of your body. The machine may rotate over the area of treatment. The machine makes noise and moves around you. But it doesn't touch you. EBRT is a lot like getting an X-ray, but it takes longer. For this treatment, you see a radiation oncologist. This is a health care provider who has extra training in the use of radiation to kill cancer cells. They decide how often you need radiation, how many sessions you may need and the best dose to treat your cancer.

Treatment Overview

How do I get ready for external beam therapy?

External beam radiation has three parts:

  • Simulation
  • Treatment planning
  • Treatment delivery

During the simulation your treatment team will figure out what position you will be in every time the treatment is given. Devices are made to make sure you are in the exact same position each time. Depending on the area being treated, small marks may be placed on your skin to guide the daily treatments. Marker seeds may be placed in the target tumor or organ. These seeds help the radiation therapist put you in the correct place during each treatment.

During the treatment planning, the treatment team uses a special computer program to set up the radiation dose that will be sent to the tumor. The plan chooses the radiation dose that will have the largest effect on the tumor and cause the least amount of harm to nearby tissues. The actual treatment can start after the simulation and treatment planning are done.

You will most likely have radiation treatment as an outpatient. This means you go home the same day. You may be instructed to modify or refrain from the use of skin products or jewelry in the area of treatment throughout the treatment course. Your treatment team will let you know if you need to do anything special to get ready for your therapy. A typical schedule is to have therapy once a day for five days a week over two to nine weeks.

What happens during external beam radiation therapy?

The treatment process usually takes 10 to 30 minutes each time. Much of the time is spent putting you in the right position. The length of treatment depends on how the radiation is delivered and the size of the dose. Each treatment facility may have its own set of guidelines. But, in general, external beam therapy follows this process:

  • You will usually get external beam therapy four or five times a week over several weeks.
  • Depending on the location of the cancer, you may need to remove clothing. If so, you will be given a gown to wear.
  • You will be carefully positioned so that the area under treatment will get the right amount of radiation. Special molds and other equipment may be used to keep you in the correct position.
  • Once the positioning and shielding have been set up, the treatment will begin. You will need to stay very still during the treatment. This is so the radiation beam will reach the cancer with the correct dose.
  • When EBRT starts, the technologist will closely watch you on a screen in another room.
  • The treatment will be painless and will last for only a few minutes.
  • You will not see, smell or feel the treatment.
  • You will not be radioactive after the treatment.

Benefits and Risks

What are the risks of external beam therapy?

EBRT can harm a growing baby. So it's important for women not to get pregnant while having treatment. Not much is known about the effects of radiation on children conceived by men during radiation therapy. Because of this, health care providers advise men not to get women pregnant during and for some weeks after radiation treatment. Talk with your provider about this issue.

External beam therapy can have side effects. Most of these go away a few weeks or a few months after treatment ends. But some side effects can be lasting and show up months or years later. The location, type and severity of side effects depend on the body part treated and the amount of radiation used. Ask your health care provider about your risk for short-term and long-term side effects from your radiation treatment.

Radiation therapy can slightly increase your risk of getting another cancer. In general, the risk is low. It’s usually outweighed by the benefit of treating the current cancer. But the risk is there. Talk with your treatment team to help decide which kind of treatment is right for you.

As with any medical procedure, there are risks linked to the procedure itself. Ask your treatment team about the risks linked to your specific treatment.

Side Effects

What are the side effects of external beam radiation?

External beam radiation therapy side effects depend on the type of cancer and treatment plan.

Side effects include:

  • Hair loss
  • Headache
  • Incontinence
  • Loss of appetite
  • Nausea and vomiting
  • Shortness of breath
  • Skin irritation, including soreness and redness
  • Tenderness

Management & Support

After each treatment, you may have fatigue, sensitive skin at the radiation site and emotional distress. Plan for extra rest and try to eat a healthy, well-balanced diet. Limit how much sun you get on sensitive skin areas. Use only lotions approved by your health care team. Your treatment team will have information on how to best manage physical side effects.

The radiation oncologist will watch your progress and how the cancer responds to each treatment. They may change the radiation dose, number of treatments or the length of treatment.

Once all treatments in your schedule are done, your health care team will let you know the follow-up schedule. You will need to return for follow-up assessments. These often include imaging tests and blood tests. These tests will tell them if the cancer was cured or if you need more treatment. You will need to make regular follow-up visits if you are cured.

Your health care team can offer you help with post-treatment support after receiving external beam radiation therapy.

Your health care team also includes: