锥形束CT测量食管癌放射治疗的摆位误差  

Setup errors in radiotherapy on esophageal carcinoma analyzed by CBCT

作　　者：谢志原[1] 林育毅[2] 王永川[1] 吴君心[3] 陈辉林[1] 邵林东[3] 陈素真[1] 潘建基[3] 

机构地区：[1]福建省安溪县医院,安溪362400 [2]厦门市第二医院 [3]福建医科大学教学医院福建省肿瘤医院放疗科

出　　处：《中国癌症防治杂志》2011年第2期125-129,共5页CHINESE JOURNAL OF ONCOLOGY PREVENTION AND TREATMENT

基　　金：福建省卫生教育联合攻关计划项目(WKJ2008-2-47-1)

摘　　要：目的利用锥形束CT在线研究食管癌放疗时的摆位误差,计算CTV到PTV的外放边界(MPTV)。方法应用医科达Synergy系统对食管癌患者治疗11例148次,分别在首次摆位后、摆位误差纠正后及治疗后行CBCT扫描,共获取444个CBCT信息,通过系统配有的匹配功能,获取的CBCT图像与计划CT图像相匹配,获取患者左右(X)、头脚(Y)和前后(Z)等3个方向的线性摆位误差,分析其摆位误差。结果 11例患者共行444次CBCT,首次摆位后CBCT扫描,系统误差(均数)±随机误差(标准差)在X、Y、Z方向上分别为(-0.17±3.62)、(1.82±3.97)、(-2.34±2.10)mm,误差纠正后再次行CBCT,结果显示摆位误差明显缩小(P<0.05)。与纠正后比较,治疗后摆位误差增大,差异有统计学意义(P<0.05)。纠正前X、Y、Z轴上MPTV分别为8.49、9.09、5.67mm,纠正后X、Y、Z方向的MPTV分别为1.80、2.47、2.21mm。结论本组病例食管癌放疗时Y方向摆位误差最大,X方向次之,Z方向最小;分次内误差在食管肿瘤治疗过程中变化明显,这在设计治疗计划时应予以考虑;通过CBCT获取食管癌患者的摆位误差并对其进行纠正,能显著降低分次间的摆位误差,提高放疗精确度,减小PTV外放边界。Objective To analyze the setup errors in radiotherapy on esophageal carcinoma by CBCT.Methods Patients received a total of 444 CBCT scans after the initial setup,re-positioning and radiation delivery.The CBCT images were registered to the planning CT images,and the setup errors on axe axes X,Y and Z were analyzed.Results a total of 11 patients received 444 CBCT.The setup errors were larger in the left-fight and superior-inferior directions comparing to the anterior-posterior direction.Compared with the initial setup errors,the re-positioning setup errors decreased significantly in all six axes（P〈0.05）.The setup errors after radiation delivery were significantly increase comparing to the re-positioning setup errors（P〈0.05）.Without real-time correction of setup errors,the estimated margins required for CTV-PTV was 8.49 mm in X-axis,9.09 mm in Y-axis and 5.67 mm in Z-axis.While with the real-time correction,the margins were only required 1.80 mm,2.47 mm and 2.21 mm in X,Y and Z axis,respectively.Conclusions The spatial distributions of setup errors were smallest in the anterior-posterior direction,moderate in the left-right direction and largest in the superior-inferior direction.The variations of intra-fractional setup error are obvious in esophageal tumors and should be taken into account during treatment planning.Real-time online correction of setup errors by CBCT can reduce the inter-fractional error,improve the precise of radiotherapy in patients with esophageal carcinoma,and reduce the CTV-PTV margin significantly.

关 键 词：食管肿瘤 锥形束CT 摆位误差 外放边界 

分 类 号：R735.1[医药卫生—肿瘤]