Frequently Asked Questions about Radiation Therapy

What is radiation therapy?

Radiation is a special kind of energy carried by waves or a stream of particles. It can come from special machines or from radioactive substances. Many years ago doctors learned how to use this energy to see inside the body and find disease. You've probably seen a chest X-ray or X-ray pictures of your teeth or your bones. When radiation is used at high levels (many times those used for X-ray exams) this energy can be used to treat cancer and other illnesses. Special equipment is used to aim the radiation at tumors or areas of the body where there is disease. The use of high-energy rays or particles to treat disease is called radiation therapy. Sometimes it's called radiotherapy, X-ray therapy, cobalt therapy, electron beam therapy, or irradiation.

How does radiation therapy work?

High levels of radiation can kill cells or keep them from growing and dividing. Radiation therapy is a useful tool for treating cancer because cancer cells are growing and dividing more rapidly than many of the normal cells around them. In addition, most normal cells appear to recover more fully from radiation effects than cancer cells. Doctors carefully limit the intensity of treatments and the amount of normal tissue being treated so that the cancer will be harmed more than you will.

What are the benefits of radiation therapy?

Radiation therapy is an effective way to treat many kinds of cancer in almost any part of the body. Half of all people with cancer are treated with radiation, and the number of cancer patients who have been cured is rising every day. For many patients, radiation is the only kind of treatment needed. Thousands of people are free of cancer after having radiation treatments alone or in combination with surgery, chemotherapy, and biological therapy.

Doctors can use radiation before surgery to shrink a tumor. After surgery, radiation therapy may be used to stop the growth of any cancer cells that remain. In some cases, instead of surgery, doctors use radiation along with anticancer drugs to destroy the cancer.

Even when curing the cancer is not possible, radiation therapy can still bring relief. Many patients find the quality of their lives improved when radiation therapy is used to shrink tumors and reduce pressure, bleeding, pain, or other symptoms of cancer. This is called palliative treatment.

Are there risks involved?

As with many other treatments for disease, there are risks for patients who are receiving radiation therapy. The brief, high-level doses of radiation that damage or destroy cancer cells can also hurt normal cells. When this happens, the patient has side effects. The risk of side effects is usually less than the benefits of killing cancer cells.

Your doctor will not advise you to have any treatment unless the benefits—control of disease and relief from symptoms—are greater than the known risks. Although it will be many years before scientists know all of the possible risks of radiation therapy, they now know that it can control cancer and help prevent its spread throughout the body.

How is radiation therapy given?

Radiation therapy can be in either of two forms: external or internal. Some patients have both forms, one after the other.

Most people who receive radiation therapy for cancer have the external type. It is usually given during outpatient visits to-a hospital or treatment center. In external therapy, a machine directs the high-energy rays or particles at the cancer and a margin of normal tissue near it.

One type of machine that is used for radiation therapy is called a linear accelerator. This machine uses the effects of electricity on subatomic particles to produce high-energy radiation for treatment. High-energy rays may also come from a machine that contains a radioactive substance such as cobalt-60.

The various machines used for external radiation work in slightly different ways. Some are better for treating cancers near the skin surface; others work best on cancers deeper in the body.

When internal radiation therapy is used, a radioactive substance, or source, is sealed in small containers such as thin wires or tubes called implants. The implant is placed directly into a tumor or inserted into a body cavity. Sometimes after a tumor has been removed by surgery, implants are put into the area around the incision to kill any tumor cells that may remain.

Another type of internal radiation therapy uses unsealed radioactive sources. The source is either taken by mouth or is injected into the body. If you have this type of treatment, you will probably need to stay in the hospital for several days.

What is radiation simulation?

Before you receive your first radiation treatment, your treatment will be planned in the radiation treatment center. This planning is called a Simulation." The simulation makes sure that the radiation will treat exactly the parts of the body where the cancer tumor is. The simulation also makes sure areas of the body that do not need radiation will be protected.

The doctor will decide where you are to receive the radiation. He or she will decide what kind of radiation will be used. Your skin will be marked with small ink dots or even a tattoo so the doctor will know exactly where to direct the radiation. A block or shield will be placed on the radiation machine to keep the radiation from treating normal tissue that needs to be protected. Finally, you will be positioned. It is very important that your body be in the same position every time Plaster casts and other devices may be used to hold you in place. This will allow the exact same areas to be treated every time you receive radiation.

The simulation is a practice run for your first radiation treatment. After the simulation is finished, everyone will be ready to start the treatment.

Notes:

Source: Radiation Therapy and You. ~ Guide to Sell-Help During Treatment, U.S. Department of Health and Human Services. Public Health Service, National Institutes of Health, National Cancer Institute. 1992.

Source: Copyright 2001, Aspen Publishers, Inc.