Radiation therapy is a common treatment for cancer. X-rays, gamma rays, and other types of radiation are directed towards the cancer cells and tumors. These rays attack the cancer cells' DNA, either directly or indirectly by creating damaging free radicals within the cancer calls. When the cancer cells are damaged, they stop reproducing and die off. The body disposes of the waste. There are three main types of radiation therapy: external-beam radiation therapy, internal radiation therapy (brachytherapy), and systematic radiation therapy. Which method is used will be determined by a variety of factors including: what kind of cancer the patient is suffering from, where the cancer is located in the body, what other treatments the patient has been given, what other ailments the patient has or had, and many other variables.
Different Types of Radiation Therapy
External-beam radiation therapy is usually administered through the use of a linear accelerator machine. During external-beam radiation, photons are directed towards the affected area and some of the normal tissue around it (because there is a chance cancer cells have begun to spread to nearby regions). There are several types of external-beam radiation: 3-dimensional conformal, intensity-modulated, image-guided, and stereotactic, to name a few. Most often, the radiation will be administered in small doses on a daily basis, for a period of a few weeks. This minimizes radiation damage to the unaffected parts of the body and also increases the probability that all the cancer cells will be affected by the treatment.
Internal radiation therapy, or brachytherapy, is just what it sounds like; radioactive materials are inserted into the body. Sometimes the radioactive material is placed inside the tumor (interstitial brachytherapy) and sometimes the material is positioned in a cavity close to the tumor (intracavitary brachytherapy). Internal radiation therapy can be administered using needles and catheters. Sometimes the radioactive sources are sealed in the body for good. This is called permanent brachytherapy. Eventually the material ceases to be radioactive. The patient will not be affected by the remaining material. If temporary brachytherapy is administered, the radioactive sources will be removed.
Systematic radiation therapy moves through the blood, killing cancer cells. It can be taken orally (either as a drink or capsules) or by injection into the vein itself. Some of the radiation will expel from the patient's body in the form of saliva, urine, and sweat. Because of the high levels of radioactivity in the first few days of this treatment, patients are usually confined in a special hospital room. If a patient is at home during systematic radiation treatment, the patient will have to be careful to avoid contact with children and pregnant women.
Like most medications and medical treatments, radiation therapy has its side effects. Fatigue, nausea, skin irritation, hair loss, bowel damage, and memory loss can occur after radiation therapy is administered.