Objective: To compare the difference of displacement between the vacuum bag fixation and the Orfit rack with thermoplastic membrane fixation of the cervical cancer patients, and to explore the individual fixation of the patients. Methods: We retrospectively analyzed the clinical data of 66 patients diagnosed as cervical cancer in Zhangzhou Municipal Hospital of Fujian Province from December 2014 to April 2016. Among them, 33 patients were fixed with vacuum bag, 33 patients were fixed with the Orfit rack with thermoplastic membrane. The cone-beam computed tomography (CBCT) images were acquired daily for the first three times of the radiotherapy, followed by once every other day for a total of 15 times. The CBCT scan images were matched with the CT scan images, and the matching results were recorded and analyzed. Results: The absolute value of the displacement in the left and right directions of the vacuum bag group was (0.28±0.30) cm, significantly lower than (0.38±0.46) cm in the Orfit rack with thermoplastic membrane group(P<0.001). The absolute value of the displacement in the anteroposterior direction of the vacuum bag group was (0.28±0.32) cm, with no significant difference of (0.27±0.23) cm in the Orfit rack with thermoplastic membrane group (P=0.580). The absolute value of the displacement in the up and down directions was (0.33±0.60) cm, with no statistically significant difference of (0.27±0.48) cm in the Orfit rack with thermoplastic membrane group (P=0.150). During the three times of CBCT scans, the differences of displacement in the left and right directions of the vacuum bag group were negligible, while apparently varied in the anteroposterior and up and down directions, however, the differences were not statistically significant (P>0.05). The change of the displacement in the three-dimensional direction in the Orfit rack with thermoplastic membrane group was marginal, and all of the differences were not significant(all P>0.05). Conclusions: Both the vacuum bag fixation and the Orfit rack with thermoplastic membrane fixation are suitable for the cone-beam CT image-guided radiotherapy of cervical cancer patients. However, the displacement in the left and right directions of the vacuum bag fixation is smaller than the Orfit rack with thermoplastic membrane fixation. During the period of treatment, the mean value of the difference of displacement in the anterior and posterior directions of the Orfit rack with thermoplastic membrane fixation is mild, which can be used individually by the patients with a flexible body and good tolerance.
目的： 比较宫颈癌患者采用真空袋固定方式与Orfit架＋热塑体膜固定方式的位移差异，探讨患者个性化的体位固定方式。 方法： 回顾性分析2014年12月至2016年4月福建省漳州市医院收治的66例宫颈癌患者的临床资料，其中33例患者使用真空袋固定，33例患者使用Orfit架＋热塑体膜固定，前3次放疗每天采用锥形束CT(CBCT)进行图像采集，之后隔天进行1次图像采集，共15次扫描，将CBCT扫描图像与CT平扫定位图像在线匹配，记录并分析匹配结果。 结果： 真空袋组患者在左右方向上的位移绝对值为(0.28±0.30)cm，明显低于Orfit架＋热塑体膜组[(0.38±0.46)cm，P<0.001]；真空袋组患者在前后方向上的位移绝对值为(0.28±0.32)cm，与Orfit架＋热塑体膜组[(0.27±0.23)cm]的差异无统计学意义(P＝0.580)；真空袋组患者在上下方向上的位移绝对值为(0.33±0.60)cm，与Orfit架＋热塑体膜组[(0.27±0.48)cm]的差异无统计学意义(P＝0.150)。前、后3次CBCT扫描过程中，真空袋组患者在左右方向上的位移变化差异均较小，在前后和上下方向上的位移变化较大，但差异均无统计学意义(均P>0.05)；而Orfit架＋热塑体膜组患者在三维方向上的位移变化均较小，且差异均无统计学意义(均P>0.05)。 结论： 对于宫颈癌患者，利用锥形束CT行图像引导放射治疗时，真空袋固定和Orfit架＋热塑体膜的固定方式均符合临床需要，但真空袋固定在左右方向上的位移较小；而Orfit架＋热塑体膜固定在治疗前后阶段的位移均值变化差异较小，对于身体灵活、耐受性好的患者，可以个体化使用。.
Keywords: Cervical neoplasms; Cone-beam computed tomography; Displacement; Positioning fixation; Radiotherapy.