摘要
目的:研究两种规格(等中心处投影0.5和1.0 cm)多叶准直器(MLC)在鼻咽癌调强放射治疗(IMRT)计划中的区别,从剂量学方面探究MLC的宽度对患者靶区和危及器官的影响。方法:随机选取已完成治疗的31例鼻咽癌患者计划,在放疗处方和物理优化参数不变的情况下分别使用两种规格MLC的加速器射野模型进行重新优化计算,统计靶区及主要危及器官的体积剂量、平均剂量(D_(mean))、适形度指数(CI)、均匀性指数(HI)等参数,分析其差异性。结果:全样本分析显示,所有靶区HI和部分靶区(PGTVnx、PCTV2)CI差异有统计学意义(P<0.05),0.5 cm MLC优于1.0 cm MLC;危及器官中,右侧视神经和视交叉最大剂量(Dmax)、左侧颞叶和右侧颞颌关节D_(mean)、左右腮腺V_(30)、气管和脊髓D_(mean)差异有统计学意义(P<0.05),0.5 cm MLC优于1.0 cm MLC,其他危及器官无统计学差异(P>0.05);在Pinnacle^(3)和Monaco计划系统中得到了相似结果,两种MLC在靶区适形度和均匀性方面及部分危及器官受量差异有统计学意义(P<0.05)。结论:0.5 cm MLC在鼻咽癌调强计划中能有效提高靶区适形度和均匀性,也能有效降低部分危及器官受量,可以更好地保护与靶区邻近或有重叠的一些危及器官,推荐有条件的医院使用。
Objective To study the dosimetric differences between multileaf collimators(MLC)of different leaf widths(projected 0.5 cm leaf width and 1.0 cm leaf width at the isocenter)in intensity-modulated radiotherapy of nasopharyngeal carcinoma(NPC),and to explore the dosimetric effect of the leaf width of MLC on target areas and organs-at-risk.Methods The treatment plans of 31 randomly selected NPC cases in Meizhou People's Hospital(Huangtang Hospital)were re-optimized by accelerator beam models using MLC of different leaf widths under the condition of unchanged radiotherapy prescription and physical optimization parameters.The dosimetric parameters of target areas and main organs-at-risk,such as dose volume parameters,mean dose,conformity index and homogeneity index,were analyzed for discussing the dosimetric differences between 0.5 cm MLC and 1.0 cm MLC.Results The analysis of the whole sample showed that the homogeneity index of all target areas and the conformity index of some target areas(PGTVnx,PCTV2)in treatment plans using 0.5 cm MLC were better than those in treatment plans using 1.0 cm MLC,with statistical differences(P<0.05).No significant difference between 0.5 cm MLC and 1.0 cm MLC was found in the dosimetric parameters of organs-at-risk(P>0.05),except for some dosimetric parameters which were significantly lower in treatment plans using 0.5 cm MLC(P<0.05),including the maximum doses of right optic nerve and optic chiasm,the mean dose of left temporal lobe and right temporomandibular joint,the V_(30) of right and left parotid glands,and the mean dose of trachea and spinal cord.Similar results were obtained in both Pinnacle^(3) and Monaco planning systems,and there were statistically significant differences between 0.5 cm MLC and 1.0 cm MLC in target dose conformation and homogeneity,as well as dose delivered to some organs-at-risk(P<0.05).Conclusion In intensity-modulated radiotherapy of NPC,0.5 cm MLC can effectively improve target dose conformation and homogeneity,and also can significantly reduce the dose delivered to some organsat-risk,so as to better protect some organs-at-risk adjacent to or overlapping with target areas.Therefore,0.5 cm MLC is recommended to be used in qualified hospitals.
作者
马天斌
蒋振东
俞海东
张汉雄
胡丹
陈意标
MA Tianbin;JIANG Zhendong;YU Haidong;ZHANG Hanxiong;HU Dan;CHEN Yibiao(Department of Radiation Oncology,Meizhou People's Hospital(Huangtang Hospital),Meizhou 514031,China)
出处
《中国医学物理学杂志》
CSCD
2021年第3期302-307,共6页
Chinese Journal of Medical Physics
基金
梅州市科技计划项目(2016B020)。
关键词
鼻咽癌
多叶准直器
适形度指数
均匀性指数
nasopharynx cancer
multileaf collimator
conformal index
homogeneity index
