When treating certain areas in the body, such as the lungs, tumors can move as the patient breathes during treatment. Before the advancement of respiratory therapy, the tumor movement had disabled the doctor's ability to precisely map the tumor location while sparing healthy tissue. By using respiratory gating during treatment, it eliminates the need to apply radiation with such a large margin, instead focusing radiation on the tumor, and sparing more healthy tissue. We are now able to treat at any point in the breathing cycle to keep the tumor in the same position for the entire treatment process.
External beam radiation (also known as traditional or whole breast radiation therapy) uses external beam radiation, like that of a regular x-ray, but the beam is highly focused and targets the cancerous area for two to three minutes. This form of treatment usually involves multiple appointments in an outpatient radiation center — as many as five days a week for five or six weeks. Certain situations may require a slightly higher dose of radiation over a shorter course of treatment, usually three to four weeks (called accelerated radiation.)
Other forms of radiation therapy can target cancer cells even better. One type is called intra-operative radiation therapy. After surgery, small amounts of cancerous cells can still remain in a child's body. So, while the child is still in the operating room and the cancerous area is exposed, doctors use special machines to give a dose of radiation before the area is stitched closed. Another type, proton-beam radiation therapy, better focuses the radiation on the cancerous tissue with the goal of causing less harm to the surrounding healthy tissue.