6D治疗床对原发宫颈癌放疗摆位误差及靶区边界的影响  

Assessments setup errors and target margin by 6D couch for primary cervical cancer

作　　者：曹倩倩[1] 朱丽红[1] 王俊杰[1] 曲昂[1] 姚丽红[1] 周舜[1] 姜树坤[1] 孙海涛[1] 林蕾[1] 

机构地区：[1]北京大学第三医院肿瘤治疗中心放疗科 ,100191

出　　处：《中华医学杂志》2015年第9期689-692,共4页National Medical Journal of China

摘　　要：目的 利用锥体束CT（CBCT）联合HexaPOD evo RT 6D床分析原发宫颈癌根治性放疗分次间及分次内摆位误差,推算临床靶区（CTV）的外放边界,为临床治疗提供依据.方法 2013年5月至2014年4月北京大学第三医院放疗科顺序入组16例原发宫颈癌患者,采用Elekta AXESSETM影像引导立体定向治疗系统,分别于校正前、6D床在线校正后、治疗后行kV-CBCT扫描,获得X线容积影像与计划CT图像自动像素-解剖结构密度配准,得出3个平移方向左右（X）、头脚（Y）、前后（Z）以及3个绕轴旋转方向Rx、Ry、Rz摆位误差,分析分次间、分次内摆位误差及CTV外放边界.结果 CBCT联合6D床在线校正明显降低了分次间X（t=3.87,P=0.000）、Z（t=-7.92,P=0.000）、Rx（t =3.05,P=0.003）、Ry（t=-6.87,P=0.000）4个方向的摆位误差,差异有统计学意义.治疗后Ry方向摆位误差较治疗前增大,差异有统计学意义（t=3.242,P=0.002）.考虑分次内摆位误差影响,6D床校正后CTV外扩边界在平移方向分别为2.74、3.90、2.87 mm.结论 CBCT联合6D床在线校正明显减小原发宫颈癌根治性放疗的平移及旋转方向摆位误差,缩小靶区外放边界,减小正常组织受量,提高放疗精确性.Objective To explore the inter and intra-fractional setup variations of HexaPOD evo RT 6-degree-of-freedom treatment couch plus kilovoltage （KV） cone-beam computed tomography （CBCT） in patients with primary cervical cancer and calculate the proper margins of CTV for clinical use.Methods From May 2013 to April 2014,16 consecutive patients with primary cervical cancer were enrolled.Elekta AXESSETM image guided radiation therapy （IGRT） modalities and vacuum pad were employed.All patents were treated in a prone position after Lac light correction.Then daily CBCT scans prior to were performed treatment delivery,another CBCT scan after 6D couch online correction and a third one after each treatment.After automatic registration to planning CT,three translational X,Y,Z and three rotational Rx,Ry,Rz shifts were analyzed for intra and inter-fraction assessments and CTV margins.Results CBCT plus 6D couch could reduce the inter-fraction errors of X （t =3.87,P =0.000）,Z （t =-7.92,P =0.000）,Rx （t =3.05,P =0.003）,Ry （t =-6.87,P =0.000） statistically and Ry was significantly different between pre and post-treatment （t =3.242,P =0.002）.As to intra-fraction variations,the CTV margins were 2.74 mm,3.9 mm and 2.87 mm on X,Y and Z directions respectively.Conclusion Corrections with CBCT and HexaPOD evo RT 6D may considerably reduce the translational and rotational setup variations and gain lower PTV volume for intact cervical cancer.Thus it protects normal tissues better and improves the accuracy of high-precision treatments.

关 键 词：放射疗法 计算机辅助 宫颈肿瘤 摆位误差 外放边界 

分 类 号：R737.33[医药卫生—肿瘤]