12. Radiotherapy and chemotherapy

X-rays were the first form of photon radiation to be used to treat cancer. The higher the energy of the x-ray beam, the deeper x-rays penetrate the target. Radiotherapy (RT) is an extremely effective treatment for oral cancer, both as a primary modality and as an adjuvant following surgery. A range of types is available (Table 1).

A planning session is needed before RT. This includes CT scan and measurements of the area to be treated, as well as skin markings to help treatment positioning. A mask immobilizes the patient's head so that radiation will only be delivered to designated areas. The total radiation dose prescribed by the oncologist is given in small amounts (fractions) usually every day for 10 to 15 minutes, 5 days in a row with a 2 day break each weekend. Most of this time is spent ensuring that blocking devices, which restrict the radiation to the appropriate area, are properly located, and patient and machine properly positioned. The daily dose must be enough to destroy cancer cells while sparing normal tissues of excessive radiation: typically 2Gy is delivered daily to a 64–70Gy total dose.