鼻咽癌调强放疗计划中脊髓分区限制剂量的研究

Limited Dose of Intensity Modulated Radiation Therapy in Spinal Cord for Nasopharyngeal Carcinoma

目的:研究鼻咽癌调强放疗计划设计时,如何在确保肿瘤靶区剂量的同时,利用分区限制剂量保护脊髓的方法降低脊髓剂量。方法:选取100例不同T分期的鼻咽癌患者,根据离靶区距离远近,将脊髓分区勾画感兴趣区域,并分别给出剂量限制优化条件,设计出满足临床需求的调强放疗计划。结果:按T分期进一步研究,各分期均值的95%置信区间上限分别为2 473cGy、2 606cGy、2 624cGy和2 956cGy,相应的终身累计剂量余量分别为3 377cGy、3 244cGy、3 226cGy和2 894cGy,未达或接近脊髓终身累计剂量限制的1/2。结论:通过分区限制剂量保护脊髓的方法可以有效降低脊髓最大剂量,减轻脊髓放射性损伤,提高患者生活质量,并为鼻咽癌复发再程放疗留有足够的脊髓余量。

Objective:To study the feasibility of an intensity modulated radiation therapy(IMRT)plan when treating nasopharyngeal carcinoma,by limiting dose to protect the spinal cord,while ensuring enough dose in the tumor target area.Methods:Totally 100 nasopharyngeal carcinoma patients in different T stages were selected for this study.We partitioned the spinal cord and delineated the areas of interest according to their distances from the target area.Then we imposed dose limit optimization conditions to each area and designed an IMRT plan that meets clinical needs.Results:In each stage,the upper limit of 95%confidence interval for the spinal cord were 2,473cGy,2,606cGy,2,624cGy and 2,956cGy,and the remain lifetime cumulative dose were 3,377cGy,3,244cGy,3,226cGy,2,894cGy,less than or close to half of the lifetime cumulative dose for spinal cord.Conclusion:Partitioning the spinal cord to limit dosage use to protect the spinal cord can effectively reduce the maximum dose used,therefore reduce the radiation damage to the spinal cord.As a result,this improves the life quality of patients and also leaves sufficient spinal cord margin for radiotherapy for recurrent nasopharyngeal carcinoma.