Physiological and biomechanical model of patient specific lung motion based on 4D CT images

Prediction of respiratory motion has the potential to substantially improve cancer radiation therapy. Tumor motion during irradiation reduces the target coverage and increases dose to healthy tissues. In this paper, we have developed a new dynamic biomechanical model of the respiratory system, permitting the simulation of a complete cycle of respiratory motion, based on the finite element method (FEM), including the real boundary conditions of the organs (the diaphragm, the thorax, mediastinum and skin behaviors) to predict the lung tumor displacement and deformation. The model is monitored by two muscles: the diaphragm and the rib kinematics. We validate our approach with real 4D CT images. The results demonstrate that the proposed approach is able to predict the respiratory motion with an average error less than 2.0 mm in the different lobes.