External Beam Radiation Therapy

External beam radiation therapy, EBRTExternal beam radiation therapy, or EBRT, is the oldest and most common method of administering radiation. It uses a complex device called a linear accelerator to aim the treatment beam at the breast area from several angles. The reason to use several angles is to minimize the effect of the beam on the skin, while achieving the highest concentration of radiation inside the breast, where the beams intersect.


Treatment Planning

The goal of effective radiation therapy is to deliver the optimal dose of cancer-damaging radiation to the breast area, with the least impact on the surrounding normal tissues. This requires an approach carefully tailored to each case.

Using special computer analysis, the radiation oncology team will determine the best angles for the beam. Then they will outline the treatment ports—places on your body where the beam will be aimed. These ports will be temporarily marked with colored ink. Don’t wash these marks off until you’re told to do so. Later, they may be replaced by tiny tattoos. These markings will ensure that the beam is aimed accurately every treatment session.

How External Beam Radiation Treatment is Given

The treatments are given by a radiation therapist in accordance with the plan developed for you by the team.

Typically, you will arrive at the facility at the appointed time each day. You may want to bring a friend for moral support during the first session or two. You may also want to bring an iPod or a book to read in case you have to wait.

schleencot-at-linacThe first external beam radiation therapy session will take longer than the others, in order to make sure the position matches the angles that were worked out during simulation.

Don’t use deodorant, because deodorants contain aluminum that may interfere with the radiation beam. Use cornstarch, or a prescription deodorant recommended by your physician. Wear a two-piece outfit so you can change easily into a patient gown from the waist up.

A external bear radiation therapy session

The treatment is given in a room that has thick concrete walls and lead-lined doors, to protect those who are outside the treatment area from radiation. The device used to deliver radiation is called a linear accelerator. At first the whole set up may seem complex and intimidating. But don’t be alarmed. A TV monitor lets the staff keep you in sight at all times, in case you need anything.

The radiation therapist will adjust the position of the machine according to the previously determined settings, then step out of the room. During the actual exposure you must remain as still as possible. The unit will be repositioned one or two times to change the angle of the beam. Each exposure lasts only a few minutes and you won’t see or feel anything.

The full course of treatment runs about five to seven weeks, with sessions from Monday through Friday, and rest and recovery periods during weekends. If you have to miss a day or two, discuss the situation with your doctor or nurse. You can make up the days at the end, but the efficiency of the treatment depends on having as few delays as possible.


The start of your therapy will depend on whether you are also undergoing chemotherapy. You may have chemotherapy and radiotherapy simultaneously, or be started on chemotherapy, then treated with radiation, then again with chemotherapy. Sometimes the delay may be as long as several weeks or several months. There is little danger of the cancer cells spreading during this delay.

During the final week you may also receive an additional dose of radiation, called the “boost”. The boost may be done with a different form of radiation, called an electron beam.

Side Effects of External Beam Radiation Therapy

Radiation therapy is a safe, proven treatment with few unwanted side effects. Most of them are not serious and disappear quickly. The most common are fatigue and skin changes. You will not have nausea or lose your hair, as you might with chemotherapy, and you certainly won’t be radioactive. Most people find that they can go through radiation therapy while maintaining their normal work schedule and lifestyle.


Stress related to your illness, daily trips for treatment, and the effects of radiation on normal cells may lead to fatigue. Most people begin to feel tired after a few weeks of radiation therapy. You can help yourself by not trying to do too much. If you feel tired, limit your activities, use your leisure time in a restful way, and try to get more sleep at night.

If you continue working a full-time job while undergoing radiation therapy, talk with your employer about adjusting your work schedule, or try working at home for a period of time.

Skin Changes

The energy waves used in external beam radiation therapy have an effect on the skin that resembles the effect of intense sunlight. Some skin irritation and redness, similar to a sunburn, may develop by the third or fourth week of treatment. Don’t rub or scratch the affected area. Use mild soap, being careful not to wash off port markings, if you have any. Wear soft clothing, preferably cotton, and protect the treated area from sunlight. Advise your doctor or nurse at once if your skin cracks or blisters, so that they can instruct you on proper care.


Other Side Effects

Radiation therapy may cause breast swelling and tenderness, so you may find sleeping on your stomach uncomfortable. Try using pillows to create a comfortable position. The swelling will subside after treatment.

In addition, you may have tenderness in the breast and chest area for up to a year, but seldom will it be severe enough to require pain medication. On a long term basis, the breast may become slightly smaller or larger. The breast may also become slightly firmer, but significant hardening is rare.

Who Should Receive Radiation Therapy?

Years ago studies showed that lumpectomy was as effective as a mastectomy, but only if the lumpectomy was combined with radiation therapy. Today, lumpectomy is almost always followed by radiation therapy. Radiation therapy is also used to treat very large cancers, or cancers that are very close to the chest wall, or lymph nodes that have cancer cells.

What to Avoid During Radiation Therapy

Certain vitamins, such as vitamins C, A, D, and E, have antioxidant properties that help cells heal. However, this healing works against the action of radiation therapy, which works by damaging cancer cells.

A well-balanced diet will give you all the vitamins that you need in amounts that will not interfere with the treatment. You can resume the supplements after you complete your course of radiation therapy.