Objective:To explore the application value of image guided technique in radiotherapy for patients with peripheral lung cancer,and to provide reference for improving radiotherapy accuracy,reducing radiotherapy damage and improving radiotherapy effect.Methods:The data of 42 cases of peripheral lung cancer patients were choosed as he research object from October 2014 to October 2016 in in our hospital.Using Varian Clinical Ⅸ medical accelerator for hypofractionated radiotherapy,tumor total dose to the planning target volume was 42 ～ 56 Gy,6 ～ 8 Gy/times,next time.There were 7 times within 2 weeks of radiotherapy.Before radiotherapy by CT scanning and enhancement scanning in patients with tumor and surrounding tissue three-dimensional images,and transmits it to the Varian eclipse planning system for radiotherapy plan design.Before the radiotherapy,the CBCT scan was used to obtain the positioning reference image,and then matched with the radiotherapy plan.According to the positioning parameters online to carry out on-line patient setup calibration,then CBCT scan data,the system comes with software,image and scanning data,obtain the location parameter matching scheme for off-line calibration parameters.Compare X,Y,Z three directions off-line calibration error and online calibration error.Using the group error algorithm of VanHerk to calculate the range of external expansion of two calibration methods.Results:Error X,online correction Y,Z three directions respectively were:X (0.1 ± 1.8) mm,Y (-0.3 ± 1.3) mm,Z (-0.6 ±-3.1) mm;Offiine three direction calibration calibration errors were:X(-0.1 ± 1.1) mm,Y(-0.2-±0.6) mm,Z(-0.9 ± 1.9) mm.Y,Z to the offline proofreading precision were significantly higher than the online correction precision.The difference was statistically significant(t =6.372,P =0.003,t =1 1.305,P =0.000).An expanding community school offline range (4.0 ～ 4.6) mm,online correction extended value (5.9 ～ 8.9) mm,the school expanded a off-line threshold range of online correction is obviously narrow.Conclusion:Image guided technique can significantly improve the positioning error of peripheral lung cancer patients in radiotherapy,and reduce the distance from the target to expand the boundary,and improve the accuracy of radiotherapy,which have high clinical value.%目的:探讨图像引导技术在周围型肺癌患者放疗中的应用价值,为提高周围型肺癌患者放疗精确度、降低放疗损伤、提高放疗疗效提供参考.方法:选择2014年10月至2016年10月我院收治的42例周围型肺癌患者作为研究对象,均采用瓦里安Clinical Ⅸ医用加速器,行大分割放射治疗,肿瘤计划靶体积总剂量为42 ～ 56 Gy,6～8 Gy/次,隔天一次,所有患者2周内行7次放疗.放疗前采用CT平扫和增强扫描,获得患者肿瘤及周围组织三维图像,并将其传输到瓦里安eclipse计划系统进行放疗方案计划设计.患者放疗前,采用CBCT扫描获取定位参考图像,再与放疗计划进行匹配,该匹配方案获取的定位参数设为在线校准参数.根据在线匹配的定位参数对患者进行在线摆位校准,再行CBCT扫描获取数据,采用系统自带软件完成图像与扫描数据的匹配,该匹配方案获取的定位参数为离线校准参数.比较X、Y、Z三个方向的离线校位误差和在线校位误差.采用VanHerk的群体性误差算法计算两种校位方法外扩界值范围.结果:在线校位X、Y、Z三个方向的误差分别为:X(0.1±1.8) mm,Y(-0.2±1.3)mm,Z(-0.5±3.1)mm;离线校位三个方向的校位误差分别为:X(-0.1±1.1)mm,Y(-0.2 ±0.6)mm,Z(-0.9±1.9)mm,Y、Z向在线校位精度均明显高于离线校位精度,比较差异有统计学意义(t=6.372,P=0.003,t=11.305,P =0.000).离线校位外扩界值范围为(4.0～4.6) mm,在线校位外扩界值为(5.9～8.9) mm,离线校位外扩界值范围明显较在线校位窄.结论:图影像引导技术可明显改善周围型肺癌患者放疗中的摆位误差,降低靶区外扩边界距离,提高放疗精度,具有较高的临床价值.
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