The Linac can be programmed to deliver electrons rather than x-rays for certain situations. The Cobalt 60 is a supervoltage machine that uses a radioactive isotope to produce gamma rays. Both machines can be used to deliver radiation to a specific, carefully mapped area of the body. Special lead blocks that fit into the treatment machine may also be customized to shield normal tissue from the radiation beam. Radiation can be delivered to several different fields, or portals, which may require repositioning the patient during the treatment time, or repositioning the treatment machine.
Treatment is given daily, five days a week.
While the consultation and the simulation may take several hours, the actual treatment time takes only several minutes. The duration of radiation therapy varies according to the type and location of the cancer. Breast cancer patients usually undergo about 25 to 30 treatments over 5 to 6 weeks on a Linac, then may receive a 1 or 2 week boost with electrons. The side effects of radiation therapy to the breast or chest wall may include reddening and irritation of the skin, a slight cough or shortness of breath if part of the lung lies in the treatment field, and a general fatigue. Within 2 to 3 weeks of the last treatment, these effects should dissipate.