基于4D-CT和Mimics软件模拟分析肺癌肿瘤的呼吸运动规律

目的：利用Mimics10.01软件和4D-CT10个呼吸时相的肺部三维模型,研究肺部肿瘤的呼吸运动规律。方法：选择1例左上肺癌患者,在肿瘤上、中、下部植入3个金标,间隔为6 mm,4D-CT扫描相位排序后重建10个呼吸时相的CT图像。将10个时相的CT图像依次导入Mimics10.01软件中,采用阈值分割、区域生长的方法提取肺部区域,重建左右肺的三维模型。测量10个呼吸时相的左右肺体积和表面积;吸气末与呼气末时相之间左肺三维模型之间的偏差也进行了分析。在每个时相的CT图像上读取植入3个金标的位置坐标,求出金标在X、Y、Z方向上质心的坐标。结果：从吸气末到呼气末左、右肺体积的变化范围分别为12.8%和12.4%,左、右肺表面积的变化范围为6.6%和6.7%。3个金标的质心变化幅度在左右、头脚、前后方向分别为2 mm,1mm和2.7 mm。结论：利用4D-CT的图像和Mimics软件重建得出的肺模型可以方便地计算肺体积以及靶区的运动范围,有利于根据患者的靶区运动特征实现个体化治疗。

Analysis of Tumor Respiratory Motion Based on 4D CT and Mimics Software

Objective：To study the feasibility of constructing a 4D lung motion model due to respiration based on 4D-CT data set and Mimics 10.01 software.Methods：4D-CT scan was performed in cine mode for one upper left lung cancer patient implanted with three gold fiducials at the interval of 6mm in superior-inferior direction.The CT images were sorted in 10 phases and transferred to Mimics 10.01.The left and right lung tissues were extracted by threshold cutting and region growing methods.The volumes and surface areas of the left and right lungs were calculated and recorded following the reconstruction and segmentation of 3 Dlungmodels.The maximum differences between ends of inhalation and exhalation for left lung was evaluated。 The coordinates of three gold fiducials were measured in CT image for all 10 phases,the variations of the mass centroid of three gold fiducials were calculated subsequently.Results：The variations of the volumes from inhalation end to exhalation end for the left and right lungs are 12.8%,12.4%,where surface differences were 6.6% and 6.7%,respectively。 The movements of mass centroid of the 3 markers were 2 mm in lateral,1mm in longitudinal,2.7 mm in vertical directions.Conclusions：The 3D models reconstructed from the 4D-CT image can be used for studying the motion of lung tumors and inner organs during the respiratorycycle.This is helpful to make a patient specific plan in radiotherapy.