光学表面监测在左侧乳腺癌放疗中的应用

Application of Optical Surface Monitoring in Radiotherapy of Left Breast Cancer

目的评估自由呼吸状态下(FB)配准CBCT和深呼吸屏气(DIBH)时光学表面监测(OSMS)在左侧乳腺癌放疗时的摆位误差和对重要器官剂量的影响。方法回顾性选择2020年5月至2020年8月于四川省肿瘤医院放疗中心采用两种不同呼吸管理治疗的16例左侧乳腺癌患者,随机分为AB两组各8例,A组(FB组)在患者自由呼吸状态下扫描得到CT模拟定位图像,并将获得的图像进行配准,B组(DIBH组)模拟定位体表轮廓与OSMS均在DIBH时获得,并将获得的图像进行配准,分别记录左右(X轴)、头脚(Y轴)、腹背(Z轴)方向的平移摆位误差数据,根据误差调整治疗床位置并治疗,对比二者的配准结果,并对其误差值进行配对t检验,并做出FH和DIBH状态下剂量学分析。结果在X,Y,Z三个方向上A组误差为0.073±0.305 cm、0.159±0.03 cm、-0.152±0.14 cm,B组误差为0.057±0.195 cm,0.057±0.195 cm,-0.106±0.005 cm,按照α=0.05水准,P<0.05,两种呼吸状态下的摆位误差有差别,B组误差<A组误差。B组患者患侧V20,患侧肺MLD,心脏v30和心脏平均受量Dmean均优于A组。结论在DIBH状态下光学表面监测的摆位误差小于FB状态的下扫描cbct摆位误差,DIBH配合光学表面监测系统不但可以减少呼吸运动对靶区的影响,还可以减少危机器官的受照体积的剂量,进而提高放疗精度。而且OSMS本身对患者不附加任何电离辐射,配准时间更快,适合应用于分次间的辅助摆位和分次内的靶区跟踪。

Objective To evaluate the setup error of free breathing(FB)registration CBCT and deep breath hold(DIBH)optical surface monitoring(OSMS)in radiotherapy of left breast cancer and its impact on the dose of important organs.Methods 16 patients with left breast cancer who received two different respiratory management treatments in the radiotherapy center of Sichuan cancer hospital from May 2020 to August 2020 were retrospectively selected patients in group A(FB)were scanned to obtain CT simulation positioning images under free breathing state,and the obtained images were registered.In group B(DIBH group),the simulated body surface contour and OSMS were obtained during DIBH,and the obtained images were registered.The left and right(x axis),head foot(Y axis),abdomen and back(Z axis)were recorded respectively.Results In X、Y、Z directions,the errors in group A were 0.073±0.305 cm,0.159±0.03 cm,-0.152±0.14 cm,and the errors in group B were 0.057±0.195 cm,0.057±0.195 cm,-0.106±0.005 cm,According to the level ofα=0.05,P<0.05,the setup error of two breathing States was different,and the error of group B was less than that of group A.The V20,MLD of lung,V30 of heart and Dmean of heart in group B were better than those of group A.Conclusion The setup error of optical surface monitoring in DIBH state is less than that of CBCT in FB state,DIBH combined with optical surface monitoring system can not only reduce the impact of respiratory movement on the target area,but also reduce the dose of radiation volume of crisis organs,thus improving the accuracy of radiotherapy.Moreover,OSMS itself does not add any ionizing radiation to patients,and the registration time is faster,so it is suitable for auxiliary positioning between fractions and target tracking within fractions.