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目的模拟肺部肿瘤在呼吸作用下的运动,探索有限元分析方法模拟肺的变形和肺部肿瘤运动的可行性。方法利用四维CT影像获得病人从吸气开始到结束各相位的图像,以计算机辅助设计表面重建方法提取吸气过程中的肺表面形态。根据吸气开始时刻表面建立有限元模型。根据各相位表面与吸气开始时刻表面的差异,提取位移载荷。将位移载荷施加到模型表面,通过有限元计算,模拟肿瘤在呼吸过程中的运动和变形。结果数值模拟表明,肺变形的误差在2 mm以内,肿瘤位移和变形的误差在1 mm以内。肿瘤在弹性模量为50 kPa时,模拟的位移和变形精度更高。结论采用有限元法可实现肺部和肺内肿瘤运动模拟,本研究为基于数值模拟的肺部肿瘤非射线追踪方法提供了依据。
Objective To simulate the movement of lung tumor under the action of respiration and to explore the feasibility of finite element analysis to simulate the deformation of the lung and lung tumor movement. Methods Four-dimensional computed tomography (CT) images were used to obtain the images of the patients from the start of inhalation to the end of each phase. Computer-aided design of the surface reconstruction method was used to extract the lung surface morphology during inhalation. The finite element model is established according to the surface at the start of inhalation. The displacement load is extracted based on the difference between the surface of each phase and the surface at the start of inhalation. The displacement load is applied to the surface of the model, and the movement and deformation of the tumor in the process of breathing are simulated through the finite element calculation. Numerical simulation results show that the error of lung deformation is within 2 mm, and the error of tumor displacement and deformation is within 1 mm. When the elastic modulus of tumor is 50 kPa, the displacement and deformation accuracy of the simulation are higher. Conclusion The finite element method can be used to simulate lung and lung tumor movement. This study provides a basis for non-ray tracing of lung tumors based on numerical simulation.