鼻咽癌图像引导放射治疗配准方法对体位校正的影响

The effect of registration method of image-guided radiotherapy for nasopharyngeal carcinoma on position correction

目的:研究并分析鼻咽癌进行图像引导放射治疗时不同配准方法对体位校正的影响。方法:选取40例鼻咽癌患者,按照随机数表法将其分为4组,即自动图像配准组、自动椎体中点配准组、手动图像配准组和手动椎体中点配准组,每组10例。4组患者分别采用4种不同配准方法,所有患者进行图像引导放射治疗,并收集此过程中所获取的52对电子射野影像,以及计划系统生成的数字重建图像。结果:自动图像配准组配准方法的靶区在X轴与Y轴方向上的摆位误差均值以及标准差分别为(1.0±3.8)mm和(-1.5±0.3)mm;自动椎体中点配准组配准方法的靶区在X轴与Y轴方向上的摆位误差均值以及标准差分别为(-1.1±4.6)mm和(-4.5±4.7)mm;手动图像配准组配准方法的靶区在X轴与Y轴方向上的摆位误差均值以及标准差分别为(1.4±3.1)mm和(-1.9±4.4)mm;手动椎体中点配准组配准方法的靶区在X轴与Y轴方向上的摆位误差均值以及标准差分别为(1.8±3.2)mm和(-3.0±3.8)mm。自动图像配准组与自动椎体中点配准组的靶区在X轴与Y轴方向上的摆位误差对比,差异均有统计学意义(t=3.572,t=5.719;P<0.05);自动椎体中点配准组与手动椎体中点配准组的靶区在X轴与Y轴方向上的摆位误差对比,差异均有统计学意义(t=-4.502,t=-2.916;P<0.05)。结论:鼻咽癌患者进行图像引导放射治疗时,选择第一颈椎体前缘中点为配准点予以自动配准最为适宜。

Objective： To study and analyze the effects of various registration method on position correction of imageguided radiotherapy for patient with nasopharyngeal carcinoma. Methods： 40 patients with nasopharyngeal carcinoma were divided into 4 groups which included automatic image registration group（AIR group, 10 cases）, automatic centrum midpoint registration group（ACMR group, 10 cases）, manual operation image registration（MOIR group, 10 cases） and manual operation centrum midpoint registration group（MOCMR group, 10 cases）. Patients of four groups respectively were implemented 4 registration methods, and all of patients received imaged-guided radiotherapy. And 52 pairs electron beam images that were obtained in the process and the digital reconstruction images that generated by plan system were collected. Results： The mean and standard deviation of position errors of target area of AIR group on the X axis and Y axis were（1.0±3.8） mm and（-1.5±0.3） mm. And they were（-1.1±4.6） mm and（-4.5±4.7） mm in ACMR group, and they were（1.4±3.1） mm and（-1.9±4.4） mm in MOIR group, and they were（1.8±3.2） mm and（-3.0±3.8） mm in MOCMR group. The differences of position errors on X axis and Y axis between AIR group and ACMR group were significant（t=3.572, t=5.719, P〈0.05）, and the differences of position errors on X axis and Y axis between MOIR group and MOCMR group also were significant（t=-4.502, t=-2.916, P〈0.05）. Conclusion： In imageguided radiotherapy for patients with nasopharyngeal carcinoma（NPC）, it is most suitable to choose the midpoint in front of hem of first cervical vertebra as the registration point to implement automatic registration