鼻咽癌不同调强放射治疗计划的剂量学比较

Comparative Dosimetric Study of Different Intensity-Modulated Radiotherapy Treatment Planning for Nasopharyngeal Carcinoma

目的:比较不同模式鼻咽癌调强放射治疗计划的剂量学差异。方法:选取同步推量放疗鼻咽癌患者20例,通过医科达Monaco 5.11治疗计划系统分别制定固定野静态调强S&S)、固定野动态调强(DMLC)和容积旋转调强(VMAT)放疗计划,评价三种计划的靶区和危及器官剂量参数、机器跳数和治疗时间。结果:靶区剂量方面,S&S与DMLC放疗计划间无统计学差异(P>0.05),而VMAT计划相较于前两者在靶区剂量均匀性上表现出明显劣势(P<0.05)。对危及器官而言,VMAT计划与固定射野调强计划相比,腮腺、口腔和喉部所受剂量都有明显增加(P<0.05),但靶区外正常组织所受剂量更低(P<0.05)。另外,VMAT计划能大幅缩短治疗时间(P<0.05),极大提高加速器工作效率。结论:VMAT调强治疗能在保证靶区剂量和保护危及器官的前提下,极大提高加速器治疗效率,比固定射野调强治疗更具优势,但须结合患者实际情况选择采用。

Objective:To compare the dosimetric differences between different intensity-modulated radiotherapy treatment planning for nasopharyngeal carcinoma.Methods:Step and shoot(S&S),dynamic multi-leaf collimator(DMLC)and volumetric modulated arc therapy(VMAT)treatment plans for 20 nasopharyngeal carcinoma cases were generated by Elekta Monaco ver 5.11 treatment planning system.The dosimetric parameters of target volume,organ at risk(OAR),the monitor units(MU)and treatment time were compared between the three kinds of IMRT treatment plan.Results:There was no significant difference in the target dose between S&S and DMLC plan(P>0.05).Compared with S&S and DMLC plan,the homogeneity index of VMAT plan for target volume was worse(P<0.05).Although VMAT plan resulted in a dose increase in some OARs such as parotid glands,oral cavity and laryngeal(P<0.05),the dose in undefined normal tissues was decreased(P<0.05).Besides,VMAT plan can significantly shorten the treatment time(P<0.05),greatly improve the efficiency of the accelerator.Conclusions:VMAT plan can ensure the absorbed dose in target volume and the safety of OARs.Although it has some significant benefits comparing with S&S and DMLC plan,the application of VMAT plan needs to be considered in the actual situation of the patients.