恶性肿瘤放射治疗设计照射野要求包括全部需要照射的瘤组织,同时尽量保护周围正常组织,以提高治疗比率。头颈部的某些肿瘤由于与中枢神经系统相近,尤需注意保护。近年新兴的模拟定位装置以及治疗计划系统(TPS)即电子计算机联合治疗设计装置,为此做出了显著贡献。 我院使用的加拿大制Therasim720型模拟定位机,主要有300MAX线球管与影象增强电视系统,可透视和拍定位片,有助于精心设计射野。1975年以来,用于鼻咽癌放疗耳前野的定位观察。 观察方法及结果对不同年龄、期别及分型(指晚期的上行型、下行型和上下行型)30余例做为观察对象。拍片条件为60—64千伏,曝光150毫安秒,时间为0.8～1秒。球管中心线束对准射野中心或定位标记中心,一般在颞颌关节前方(使鼻咽腔 Radiation fields designed for the treatment of malignant tumors require all the tumor tissues that need to be irradiated, and at the same time try to protect the surrounding normal tissues to increase the treatment rate. Some tumors of the head and neck are closely related to the central nervous system and need special care. In recent years, an emerging analog positioning device and a treatment planning system (TPS), which is an electronic computer combined therapy design device, have made significant contributions to this end. The Canadian-made Therasim 720 analog positioning machine used in our hospital mainly includes a 300-mm line tube tube and video-enhanced television system, which can see through and photograph the positioning sheet, which helps to carefully design the field. Since 1975, it has been used for the observation of localization of nasopharyngeal cancer radiotherapy. Observation methods and results More than 30 cases of different ages, stages, and types (referring to the late ascending, descending, and ascending and descending types) were observed. Filming conditions are 60-64 kV, exposure 150 mA seconds, time is 0.8 to 1 second. The center line of the tube is aligned with the center of the field or the center of the positioning mark, generally in front of the temporomandibular joint (making the nasopharyngeal cavity