Radiation therapy can be given using different techniques. External beam radiation is where a machine outside your body aims radiation at cancer cells. This is generally given every day over a few weeks. Internal beam radiation (also known as brachytherapy) is where a radiation source is put closer to areas at risk (for example placed intravaginally). This is generally given in three to five short treatments. Sometimes patients require both forms of radiation therapy. New techniques, such as IMRT and 3-D conformal radiation therapy allow your doctor to aim higher doses of radiation at your cancer while reducing the radiation to nearby healthy tissue with the assistance of technology.
Radiation therapy does not kill cancer cells right away. It takes days or weeks of treatment before cancer cells start to die. Cancer cells continue to die for weeks or months after radiation therapy ends.
Radiation not only kills and slows the growth of cancer cells; it can also affect nearby healthy cells. The healthy cells almost always recover after treatment is over. There are many techniques used to minimize the effects of radiation on your healthy normal tissues.