头颈部肿瘤(如鼻咽癌)是我国高发的恶性肿瘤之一,放射治疗是其主要的治疗手段,其放射治疗成功的关键在于每次实施照射时,靶区都能得到准确的剂量,同时邻近周围正常组织和要害器官得到充分的防护。随着放射治疗技术的发展,各种先进的方法、手段,如三维治疗计划系统、适形放射治 Head and neck cancer (such as nasopharyngeal carcinoma) is one of the high incidence of malignant tumors in our country. Radiation therapy is the main treatment method. The key to the success of radiotherapy is that the target area can get accurate dose for each irradiation. At the same time, the surrounding normal tissues and vital organs are adequately protected. With the development of radiation therapy technology, various advanced methods and means, such as three-dimensional treatment planning system, conformal radiotherapy