摘要
A simple procedure to plan, verify and implement craniospinal irradiation（CSI） with patients supine is presented. Treatment is conducted with a single posterior spinal field abutting two lateral cranial fields. The opposed lateral fields are half-blocked and the inferior line is perpendicular. The posterior field uses some fixed field parameters so that the cephalad edge of the posterior field is coplanar with the caudal edges of the lateral fields and it is independent of the height of the couch. A steel-shot ball is used to measure the size of overlap or gap at the junction using portal images of an electron portal image device or portal films. The results of analyzing the portal images show that the errors of the junction are within ± 1 mm. The dose-volume histograms （DVHs）show that there are not unbearable hot or cold spots in the clinic target volumes （CTVs）. Supine craniospinal treatment is a reliable and convenient alternative to treatment in the prone position and avoids the technical difficulties of the latter. The use of fixed field geometry greatly facilitates treatment planning and effectively reduces the amount of time of setup, verification and treatment.
提出了一种全新的仰卧位全中枢神经系统放射治疗技术,包括计划、验证和执行.治疗采用2个侧向全颅野加一个背侧的全脊髓野,2侧全颅野采用半野技术,下界共面并垂直于地面;固定全脊髓野一些参数以方便设计及摆位,并且上界与全颅野下界共面.贴一4mm直径的金属小球在衔接处,通过射野摄片确定衔接野的误差.结果显示衔接野误差小于1mm.剂量体积直方图表明在临床靶体积内没有不可接受的剂量热点和冷点.仰卧位全中枢神经系统放射治疗技术方便可靠,完全可以替代传统的俯卧位技术,解决了俯卧位技术无法解决的剂量冷、热点问题.固定射野参数大幅度降低了计划设计的难度,并且有效减少了患者摆位、验证和治疗的时间.
