Radiation therapy is a cancer treatment that uses high doses of radiation to kill cancer cells and stop them from spreading. At low doses, radiation is used as an x-ray to see inside the body and take pictures, such as x-rays of teeth or broken bones. Radiation in cancer treatment works in much the same way, except that it is given at a higher dose.
Radiation therapy can be external beam (using a machine outside the body aiming radiation at cancer cells) or internal radiation (when radiation is put inside the body, in or near the cancer cells.)
Many people with cancer need radiation therapy. More than half (about 60 percent) of people with cancer get radiation therapy. Given in high doses, radiation kills or slows the growth of cancer cells. Radiation therapy does not kill cancer cells right away. It takes days or week of treatment before cancer cells start to die. Then, cancer cells keep dying for weeks or months after radiation therapy ends.
Just like chemotherapy, radiation not only kills or slows the growth of cancer cells, it can also affect nearby healthy cells.The healthy cells most always recover after treatment is over. In order to avoid killing healthy cells, the radiation oncologist uses the lowest does of radiation possible to balance between being high enough to kill cancer cells, yet low enough to limit damage to healthy cells. Radiation is spread out over several weeks allowing normal cells to recover while cancer cells die. The radiation oncologist also aims the radiation at a precise part of the body using new techniques such as IMRT and 3-D conformal radiation therapy.
Radiation therapy does not hurt while it is being given. The side effects that people get from radiation can cause pain or discomfort. They include fatigue, skin changes, diarrhea, hair loss in the treatment area, mouth problems, nausea and vomiting (depending on the area being treated), swelling, trouble swallowing, urinary and bladder changes.
External beam radiation therapy comes from a machine that aims radiation at the cancer area. The machine is large and makes various noises as it moves around. It does not touch the body, but rotates around, sending radiation to the body from different directions.
Most people get external beam radiation therapy once a day, 5 days a week, Monday through Friday. Treatment lasts for 2 to 10 weeks, depending on the type of cancer a person has and the goal of treatment.
At the beginning of treatment, the oncologist will define the treatment area. A CT scan is done to define this area and decide how much of the body will be radiated. Small tattoos are put on the skin to mark the treatment area. The radiation therapist uses the tattoos each day to make sure the body is in the correct position. A mold is also made for the neck and head area so that each day during treatment, the head and neck are held in the exact position to keep the person being treated from moving. Red lazer beams guide the radiation therapist to line up the body to the exact measurements and positions as prescribed by the radiation oncologist.
Every day the person being treated will report to the radiation area, change clothes into a hospital gown to expose the area being treated. The patient will then lie down on the radiation table while the radiation therapists get the body into the exact position to treat the same area every day during the course of treatment. At actual beam of radiation to the body lasts anywhere from 15 seconds to several minutes, depending on the type of cancer being treated.
