Radiation Therapy

Radiotherapy, also called radiation therapy, is the treatment of cancer and other diseases with ionizing radiation. Ionizing radiation deposits energy that injures or destroys cells in the area being treated (the target tissue) by damaging the genetic material (DNA) in the individual cells, making it impossible for them to continue to grow.



Although radiation damages both cancer cells and normal cells, normal, healthy cells are able to repair themselves and return to proper functioning.Radiotherapy may be used to treat localized solid tumors, such as those cancers associated with the oral environment. It can also be used to treat leukemia and lymphoma (cancers of the blood-forming cells and lymphatic system, respectively).



Prior to starting radiation therapy treatments a planning session, or simulation, is conducted. This involves special x-rays or CAT scan pictures and measurements of the area to be treated, as well as markings (long lasting, but not permanent tattoos) being placed on the patient's skin to help with positioning during the actual treatments. This planning session may take up to an hour to complete, but is essential in providing data for optimal treatment planning. For oral cancers, as well as most head and neck cancers, a porous mesh mask will be made during this procedure. When used in the radiation treatment room, the mask immobilizes the patients' head during treatment. This is very important so that radiation will only be delivered to the designated areas.



The total dose of radiation therapy prescribed by the radiation oncologist is broken down into small amounts (fractions) which are given on a daily basis, usually five days in a row with a two day break each week. It has been found that patients better tolerate the smaller daily doses while still receiving the maximum benefit of the treatments. Normally, each daily treatment lasts about 10 to 15 minutes, with the majority of this time spent making sure the radiation blocking devices, which limit the radiation to the appropriate area are properly in place, and the patient and machine are properly positioned. It actually takes more time to set up the machine and the patient than it does to deliver the dose of radiation. The staff members who are responsible for managing the daily radiation therapy treatments have received specialized education and certification and are called radiation therapists.



The reason that the treatment course for some cancers is so relatively long (2-8 weeks) is to allow for normal tissue repair after each exposure to radiation, and to minimize permanent injury. (Tissue repair can also be helped by proper nutrition and a positive mental state. See recommendations for nutrition during treatment elsewhere on this site.) The daily dose must also be great enough to destroy the cancer cell while sparing the normal tissues of excessive levels of radiation. This balancing act forms the basis of modern radiation therapy.