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Mooney-Rivlin Biomechanical Modeling of Lung with Inhomogeneous Material Property


J Nasehi Tehrani

J Nasehi Tehrani1*, X Guo2 , J Wang1 , (1) UT Southwestern Medical Center, Dallas, Texas, (2) University of Texas, Richardson, Texas

Presentations

TU-G-CAMPUS-J-2 (Tuesday, July 14, 2015) 4:30 PM - 5:00 PM Room: Exhibit Hall


Purpose: The Mooney-Rivlin material with hyperelastic strain energy has been proposed for realistic biomechanical modeling of lung. In this study, the lung is modeled as an inhomogeneous Mooney-Rivlin material with the incompressibility factors being optimized to improve the tumor center of mass (TCM) motion simulation accuracy during respiration.
Method: ITK-SNAP was used to segment lungs of eight lung cancer patients from the 4D-CT images and tetrahedral volume meshes of the lungs in phase 50% were created by using adaptive mesh generation toolkit. The interphase deformation vector fields (DVFs) are calculated by demons deformable registration algorithm and the barycentric coordinate system of tetrahedral elements is obtained from the resulted DVFs. Mooney-Rivlin hyperelastic material is used to model the lung volume. Each element is considered unique where the incompressibility factor (k-factor) for each element is assumed to be proportional to the magnitude of normalized DVF. The incompressibility factor for each element was optimized by minimizing the tumor center of mass motion simulation error.
Results: If lung is considered as a homogenous material in Mooney-Rivlin modeling, the average TCM motion simulation error is 2.26 mm. By considering inhomogeneous properties of lung in the proposed strategy, the average TCM motion simulation error is reduced to 2.04 mm.
Conclusions: We proposed a method for assigning the inhomogeneous biomechanical material in the Mooney-Rivlin model of lung based on the lung regional deformation vector fields. Inhomogeneous material property of lung improves the simulation accuracy.



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