Abstract

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

Author(s):: LEI Jinyan; HE Yang; LUO Huanli; YAN Tingcan; LI Jianfeng; PENG Haiyan; JIN Fu; Department of Radiation Oncology, Chongqing Cancer University Cancer Hospital/Chongqing Cancer Institute/Chongqing Cancer Hospital, Chongqing 400030, China

Keywords:: ; Keywords: cervical cancer; Tomotherapy; aspect ratio; setup error

Abstract:: 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.