【摘要】 目的根据螺旋断层放射治疗(TOMO)过程中每日进行的兆伏(MV)级CT扫描的图像研究鼻咽癌患者外体形变化和摆位误差变化的相关性。方法入组10例行TOMO的鼻咽癌患者,每例患者每次治疗前进行MV级CT扫描,共有千伏(KV)级CT图像10组,MV级图像322组,然后进行图像配准获得摆位误差。分别在MV级CT图像和模拟CT图像上勾画出患者的头部外轮廓,并将所有MVCT上的外轮廓通过配准映射至KVCT图像上,分别计算相应重叠的体积,根据体积数据分析体形变化与摆位误差的相关性。结果在放射治疗整个过程中,10例患者中7例有消瘦的情况发生,主要开始在治疗15~20次之间。相关分析中,10例患者中仅3例Y轴平移有相关性,患者编号为1,3,10,相关系数为0.622,-0.76,-0.53(P<0.05)。结论从螺旋断层放射治疗前到放射治疗15~20次期间,鼻咽癌患者头部有明显体积变化,但体积变化与摆位误差没有强相关性。更多还原

【Abstract】 Objective To study correlation between variations of facial contours and setup errors for patients with nasopharyngeal carcinoma based on daily megavoltage coreputed tomography(MVCT) during helical tomotherapy. Methods 10 patients with nasopharyngeal carcinoma treated with helical tomotherapy were enrolled in this study. Each patient underwent pre-fraction MVCT in five fractions a week. The numbers of kilovoltage computed tomography(KVCT) and MVCT images were totally 10 and 322, respectively. Setup error was obtained using image registration. External facial contour for each patient was delineated on MVCT and KVCT images. For each patient, all the facial contours on MVCT were then mapped onto KVCT based on image registration. The overlapped facial volume on each MVCT and KVCT images was computed. Finally, correlation between variations of facial contours and setup errors was analyzed. Results Facial shrinkage was observed in 7 of 10 cases and occurred mainly from 15 th to 20 th fraction. Correlation between facial shrinkage and set-up translation on y axis was found in 3 cases(No.1,3,10) with a coefficient of 0.622,-0.76,-0.53(P<0.05), respectively. Conclusion Compared with the facial volume of patients with nasopharyngeal carcinoma before tomotherapy treatment, significant volumetric shrinkage occurred from 15 th to 20 th fraction. But there is no strong correlation between volumetric changes and setup errors.更多还原