不同体位固定方式对乳腺癌放疗摆位精度的影响

目的:探讨使用4种不同体位固定方式用于乳腺癌放疗定位，并对4种不同的固定方式的摆位精度分析和比较，为临床应用提供参考。方法:选取2018年11月至2019年1月我院收治的乳腺癌放疗患者34例，其中乳腺癌保乳术后患者20例，乳腺癌根治术后（锁骨上下区放疗）患者14例。将乳腺癌保乳术后患者20例分为A、B两组，分别采用负压垫加头膜固定和乳腺托架固定；将乳腺癌根治术后患者14例分为C、D两组，采用颈肩膜固定（C组双手置于体侧）(D组患侧手抓耳)。用Philips Bigbore大孔径CT模拟机进行定位扫描，图像传输到Varian Ecplipse治疗计划系统进行重建，计划设计。对所有参与研究的患者首次治疗完成后，进行CT下复位验证，并将验证图像与计划图像配准，测量治疗中心坐标误差，用SPSS 18.0统计软件对数据进行统计分析，给出摆位误差。结果:A组在X、Y、Z方向上的摆位误差分别为（1.7±1.9） mm、（2.1±2.9） mm、（2.0±1.2） mm；B组在X、Y、Z方向上的摆位误差分别为（2.8±1.1） mm、（3.7±1.1） mm、（4.8±1.3） mm；C组在X、Y、Z方向上的摆位误差分别为（2.1±1.6） mm、（2.1±1.5） mm、（3.6±3.1） mm；D组在X、Y、Z方向上的摆位误差分别为（1.0±0.5） mm、（1.9±1.5） mm、（3.6±1.9） mm。A组在Y、Z方向的摆位误差小于B组（P=0.048、0.038），A、B两组在X方向的摆位误差比较，差异无统计学意义（P>0.05）；C、D两组在X、Y、Z方向的摆位误差比较，差异无统计学意义（P>0.05）。结论:乳腺癌保乳术后患者的放疗，全乳加锁骨上的一体化的调强技术，用负压垫加头膜固定技术比用乳腺托架固定技术减少了摆位误差；乳腺癌根治术后患者放疗，用颈肩膜固定技术的两种体位对摆位误差无太大差异，为了减少相邻野衔接问题引起的剂量误差建议采用手抓耳体位。

Effects of different fixation methods on positioning error of breast cancer radiotherapy

Objective:To investigate the application of four different fixation methods for breast cancer radiotherapy positioning,and analyze the positioning accuracy,so as to provide reference for clinical application.Methods:From November 2018 to January 2019,a total of 34 cases of breast cancer radiotherapy patients were selected,which included 20 cases had breast conserving surgery and 14 cases of breast cancer patients after radical surgery(radiotherapy in the supraclavicular region).20 cases of breast cancer patients after breast conserved surgery were divided into group A and group B,A used vacuum pad and head thermoplastic mask fixation,B used breast bracket.14 cases of breast cancer patients after radical surgery were divided into group C and group D,respectively used neck and shoulder thermoplastic mask(C hands side,D hands grasping ears).We can use Philips Bigbore CT to perform positioning scanning,and transfer images to the Varian Ecplipse treatment planning system for reconstruction and plan design.After the first treatment,patients must complete CT scan,so we can register verified image with the planned image,measure the coordinate error of the treatment center,and then use SPSS18.0 statistical software for statistical analysis of the data,then get the positioning error.Results:The positioning errors of group A in the X,Y and Z directions were(1.7±1.9)mm,(2.1±2.9)mm and(2.0±1.2)mm,respectively.The positioning errors of group B in the X,Y and Z directions were(2.8±1.1)mm,(3.7±1.1)mm and(4.8±1.3)mm,respectively.The positioning errors of group C in the X,Y and Z directions were(2.1±1.6)mm,(2.1±1.5)mm and(3.6±3.1)mm,respectively.The positioning errors of group D in X,Y and Z directions were(1.0±0.5)mm,(1.9±1.5)mm and(3.6±1.9)mm,respectively.The positioning error of group A in the Y and Z directions was smaller than that of group B(P=0.048,0.038),and there was no significant difference in the positioning error of group A and group B in the X direction( P >0.05).There was no significant difference in the positioning error between C group and D group in the X,Y and Z directions( P >0.05). Conclusion: Radiotherapy for breast cancer conserving surgery,the vacuum pad and head thermoplastic mask fixation can reduce the positioning error compared with the breast bracket.For breast cancer patients after radical surgery,there is no significant difference in positioning error between the two fixation techniques by neck and shoulder mold,so it is recommended to use the ear grasping method to reduce the dose error caused by the connection between adjacent fields.