鼻咽癌患者放疗期间鼻咽部与颈部线性摆位误差的差异  

Differences of Linear Setup Error Between Nasopharynx and Neck During Radiotherapy for Nasopharyngeal Carcinoma Patients

作　　者：许健柱 罗经杰 邓源 邝倍 林耿贤 叶锡渠 邹金华[1] Xu Jianzhu;Luo Jingjie;Deng Yuan;Kuang Bei;Lin Gengxian;Ye Xiqu;Zou Jinhua(Department of Radiation Oncology,Nanfang Hospital of Southern Medical University,Guangzhou Guangdong 510515,China)

机构地区：[1]南方医科大学南方医院放疗科,广东广州510515

出　　处：《医疗装备》2021年第9期1-3,共3页Medical Equipment

摘　　要：目的利用锥形束CT(CBCT)图像引导系统,分段统计鼻咽癌患者放疗线性摆位误差,分别计算鼻咽部临床靶区CTV1及颈部临床靶区CTV2到计划靶区(PTV)的外扩边界(MPTV),总结影响鼻咽癌放疗线性摆位误差的因素。方法选择2019年4—8月在南方医科大学南方医院接受瓦里安Trilogy直线加速器治疗的99例鼻咽癌患者,在首次治疗前及在疗程中每隔1周行1次摆位后CBCT获取图像,将其与定位时的kV CT图像分别进行CTV1及CTV2感兴趣区域配准,分别记录X、Y、Z轴上的线性摆位误差且行t检验及Q检验,并利用MPTV=2.5Σ+0.7δ计算MPTV。结果CTV2线性摆位误差>2.0 mm的频数明显多于CTV1;CTV1的MPTV基本保持在0.30 mm以内;CTV2的MPTV略大于CTV1,总体在0.50 mm以内;CTV1与CTV2在3个方向上的线性摆位误差比较,差异均有统计学意义(P<0.05);CTV1及CTV2在3个方向上不同扫描时间的线性摆位误差比较,差异均无统计学意义(P>0.05)。结论鼻咽癌患者CTV1与CTV2在3个方向上的MPTV略有差异,故CTV-PTV外扩应分开CTV1与CTV2两个感兴趣区域;由于CTV1及CTV2在3个方向上不同扫描时间的线性摆位误差无明显差异,故建议在医嘱上适当增加CBCT扫描次数。Objective Using cone beam computed tomography(CBCT)image-guided system,the linear setup errors of nasopharyngeal carcinoma patients underwent radiotherapy were counted by segments,and the margin of planning target volume(MPTV)from the nasopharyngeal clinical target volume(CTV),defined as CTV1,and neck CTV,defined as CTV2,to the planned target volume(PTV)were calculated respectively.Then the factors influencing the linear setup errors of nasopharyngeal carcinoma radiotherapy were summarized.Methods From April to August in 2019,99 patients with nasopharyngeal carcinoma who were treated by Varian Trilogy linear accelerator in Nanfang Hospital of Southern Medical University were selected.CBCT images were obtained before the first treatment and after positioning biweekly during course of treatment,and then the images were registered with the kV CT images at positioning of CTV1 and CTV2 regions of interest respectively.The linear setup errors on X,Y and Z axes were recorded,and t-test and Q-test were performed.MPTV was calculated according to the equation of MPTV=2.5Σ+0.7δ.Results The frequency of positioning error>2.0 mm of CTV2 was significantly more than that of CTV1;The MPTV of CTV1 was basically kept within 0.30 mm;The MPTV of CTV2 was within 0.50 mm,slightly larger than that of CTV1.When the linear setup errors of CTV1 and CTV2 were compared on 3 axes,all the differences were statistically significant(P<0.05);When the linear setup errors in three directions at different scan times were compared,all the differences were not statistically significant(P>0.05).Conclusion The MPTV of CTV1 and CTV2 of nasopharyngeal carcinoma patients are slightly different in three directions,so CTV-PTV expansion should separate CTV1 from CTV2 regions of interest;Since there is no significant difference in the linear setup errors of CTV1 and CTV2 at different scan times in three directions,it is suggested that the number of CBCT scanning should be appropriately increased in the doctors'orders.

关 键 词：鼻咽癌 锥形束CT 线性摆位误差 计划靶区外扩边界 

分 类 号：R730.55[医药卫生—肿瘤]