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[目的]分析采用个体化加长真空垫+热塑网状头颈肩膜体位固定技术实施调强放疗的鼻咽癌患者放疗期间摆位误差的大小及其体重的变化趋势。[方法]鼻咽癌患者23例,整个疗程1～6个周次中每周拍摄正侧位EPID图像一次并测量患者体重。将EPID图像与计划CT所生成的DRR图像进行配准,利用获得的配准差值分析摆位误差的大小及其在不同周次间的差异,同时分析患者体重的变化对摆位误差的影响。[结果]不分周次的情况下,头脚、腹背、左右三个方向的摆位误差分别为0.165±0.121cm、0.064±0.122cm、0.038±0.135cm。按不同周次进行划分,头脚、腹背、左右各个方向在6个不同周次的摆位误差无明显差别(P均>0.05)。Bivariate相关分析结果显示头脚、腹背、左右三个方向上的偏移幅度与体重变化均无关(r=0.147,P=0.152;r=0.102,P=0.321;r=0.114,P=0.267)。[结论 ]采用个体化加长真空垫+热塑网状头颈肩膜体位固定技术实施调强放疗的鼻咽癌患者在整个疗程中的摆位具有较好的准确性与重复性,患者体重的变化对摆位误差无明显影响。
[Objective] To analyze the variation of setting error and body weight during radiotherapy in patients with nasopharyngeal carcinoma treated by intensity-modulated radiotherapy with an individualized elongated vacuum pad and thermoplastic mesh head and neck shoulder and shoulder position fixation. [Methods] Twenty-three patients with nasopharyngeal carcinoma (NPC) were enrolled. The EPID images were taken once a week and the body weight of the patients were measured weekly. The registration of the EPID image and the DRR image generated by the planning CT was used to analyze the difference of the setup error and the difference between the different weeks by using the obtained registration difference and the influence of the change of the patient weight on the setup error . [Results] The setup errors of head, back, left and right were 0.165 ± 0.121cm, 0.064 ± 0.122cm and 0.038 ± 0.135cm, respectively. Divided by different weeks, the head, abdomen, left and right in all directions in six different weeks set error was no significant difference (P all> 0.05). The results of Bivariate correlation analysis showed that the amplitude of head, abdomen, left and right directions had no relation with body weight changes (r = 0.147, P = 0.152; r = 0.102, P = 0.321; r = 0.114, P = 0.267). [Conclusion] The localization of the patients with nasopharyngeal carcinoma treated by intensity-modulated radiotherapy by using the individualized and extended vacuum pad + thermoplastic mesh head and neck shoulder-and-shoulder immobilization technique has good accuracy and repeatability during the whole course of treatment. The change of body weight No significant effect on setting error.