宫颈癌放疗中患者体型改变的特征量与摆位误差的关联

目的:评估宫颈癌患者在螺旋断层放疗（TOMO）中耻骨联合上缘层面的横纵轴宽度比值（简称横纵比）与摆位误差的关联。 方法:选取行TOMO的宫颈癌患者30例，采用热塑体膜固定，利用图像引导系统获取分次摆位MVCT图像，并与定位kVCT图像进行配准，记录左右、腹背、头脚方向上的摆位误差。记录每分次患者的横纵比，并将其与摆位误差进行Pearson相关性分析。 结果:对于横纵比稳定性>0.8的18例患者，其横纵比与头脚和腹背方向上的随机误差、年龄、体质量指数都呈显著负相关，关联系数R分别为-0.621、-0.488、-0.560、-0.552（P=0.006、0.040、0.016、0.017）。横纵比稳定性<0.8的12例患者中，其年龄、体质量指数与δ横纵比的相关性系数R分别为-0.796、-0.566（P=0.002、-0.055）。结论:在宫颈癌患者TOMO中，横纵比可以作为一个临床观测指标，评估摆位误差的大小。

Correlation between the characteristic variation of body shape and setup errors in radiotherapy for cervical cancer

Abstract: Objective To evaluate the correlation between the characteristic variation (the aspect ratio) of superior margin of pubic symphysis and setup errors during Tomotherapy for cervical cancer. Methods Thirty cervical cancer patients treated with Tomotherapy were enrolled in this study. After the initial positioning with thermoplastic membrane, the online registration between MVCT images and original kVCT positioning image was performed, and the setup errors in left-right, anterior-posterior, and superior-inferior directions were recorded. Meanwhile, the aspect ratio were also recorded in every faction and then compared with the setup error using Pearson correlation analysis. Results The aspect ratio of 18 patients (aspect ratio stability>0.8) had significant negative correlations with setup errors in superior-inferior and anterior-posterior directions, age and body mass index; and the correlation coefficients were -0.621, -0.488, -0.560, -0.552 (P=0.006, 0.040, 0.016, 0.017). For the other 12 patients (aspect ratio stability<0.8), the corresponding correlation coefficients between δaspect ratio and age, body mass index were -0.796, -0.566 (P=0.002, -0.055). Conclusion For cervical cancer patients treated with Tomotherapy, the aspect ratio can be used as a clinical observation index to assess the setup error.