肺部肿瘤运动的数值模拟

Numerical simulation on lung tumor motion

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 investigate the feasibility of simulating the deformation and displacement of lung tumors by simulating the motion of lung tumors during respiration using finite element method （FEM）. Methods The CAD （computeraided design） surfaces of the lung at multiple inhalation phases were reconstructed from 4D CT images of a patient with lung tumor. The finite element model was established according to the surface at the be ginning of inhalation. Distributed surface loads were defined by the differences between each individual surface and the surface at the beginning of inhalation, and applied to the surface of the model. The motion and deforma tion of lung tumors were then simulated using FEM within the inhalation cycle. Results The numerical simulation indicated that the estimated errors for the lung and the tumor＇ s motion and deformation were less than 2 mm and 1 mm, respectively. The use of linear elastic relationship for tumor with elastic modulus of 50 kPa could achieve higher precision in simulation. Conclusions The deformation of lung and the displacement of lung tumor are pos sible to be simulated accurately by FEM. This research provides references for the Xray free lung tumor tracking method based on numerical simulation.