OSMS在乳腺癌术后放疗临床应用中体位固定方式优选研究

目的光学体表监测系统(Optical Surface Monitoring System,OSMS)在乳腺癌术后放疗应用中,通过对比真空垫和颈胸膜两种固定方式条件下锥形束CT(Cone Beam CT,CBCT)的摆位误差和OSMS相对于CBCT方式的摆位一致性,确定优选固定方式。方法回顾性分析52例利用OSMS系统摆位的乳腺癌患者病例数据,其中真空垫固定组(A组)24例,颈胸膜固定组(B组)28例,将CBCT与定位CT配准误差记为摆位误差;取OSMS得到的六维配准误差与CBCT配准结果的差值,绝对化后用于量化摆位一致性。比较两种固定方式的摆位误差和摆位一致性的差异及其累积分布情况。结果摆位误差除z方向外,A组均优于B组,x、z方向差异有统计学意义(P<0.05);摆位一致性除z方向外,A组均优于B组,x、y、z、Pitch、Roll方向差异有统计学意义(P<0.05);摆位误差累积分布除z方向外,A组均优于B组,z方向具有统计学差异(P<0.05);摆位一致性累积分布除z方向外,A组均优于B组,x、y、Rtn、Pitch、Roll方向具有统计学差异(P<0.05);6维方向摆位一致性累积分布A组优于B组(P<0.05)。结论乳腺癌术后放疗OSMS摆位两种体位固定方式均可满足临床要求;相对于OSMS摆位颈胸膜固定,真空垫固定方式的摆位一致性整体优于前者,一定程度上减小了摆位误差,并可在治疗中实时监测,可使患者受益,应予以优先使用。

Study on Optimal Postural Immobilization Method of OSMS in Clinical Application of Postoperative Radiotherapy for Breast Cancer

Objective In the application of optical surface monitoring system(OSMS)in postoperative radiotherapy for breast cancer,the optimal postural immobilization method is determined by comparing the setup error of cone beam CT(CBCT)and the consistency of OSMS relative to CBCT under the conditions of vacuum pad fixation and neck and thorax thermoplastic mask fixation.Methods The data of 52 breast cancer patients who were placed by the OSMS system were retrospectively analyzed,including vacuum pad fixation group(group A,n=24)and neck and thorax thermoplastic mask fixation group(group B,n=28).The registration error between CBCT and CT was recorded as setup error,and the difference between six-dimensional registration error obtained by OSMS and CBCT registration result was used to quantify the consistency of setup after absolutization.The difference and cumulative distribution of setup error and position consistency of the two fixed modes were compared.Results Except for the z direction,the setup error in group A was better than group B,and there was significant difference between x and z direction(P<0.05).Except for the z direction,the consistency of setup was better in group A than in group B,and there was significant difference in x,y,z,Pitch and Roll direction(P<0.05).Except for the cumulative distribution of the setup error in the z direction,group A was basically better than group B,and there was a significant difference in the z direction(P<0.05).Except for the z direction,the consistent cumulative distribution of setup in group A was better than group B,and there were significant differences in x,y,Rtn,Pitch,and Roll directions(P<0.05).The consistent cumulative distribution of six-dimensional setup in group A was better than group B(P<0.05).Conclusion Two immobilization techniques of OSMS setup can meet the clinical requirements in postoperative radiotherapy for breast cancer patients.Compared with OSMS setup neck and thorax thermoplastic mask fixation,the setup consistency of OSMS setup vacuum pad fixation is better than the former,which reduces the setup error to a certain extent,and can be used real-time monitoring in treatment and bring benefit to patients,so it should be used in priority.