Anisotropic computational modeling of bony structures from CT data segmentation and analysis

The use of modelling techniques that combine CT data and bone tissue micromechanics is spreading in computational biomechanics. Patient-specific FE models can be developed by assigning orthotropic elastic properties depending on CT attenuations to help the surgical planning of interventions or the prediction of stress and strain fields in many conditions. The model accuracy is crucial in numerical results, as it affects reliability of computations. The key point was to build a model complying with bone anisotropy and material inhomogeneity. For this purpose, a procedure for the automatic assignment of mechanical properties to bony structures was defined. Starting from CT data of the jaw, the voxel-specific elastic properties were computed for defining the mandibular FE model with validated and reliable material properties. A novel procedure is proposed for the calculation of the principal material directions, which is based on the HU gradient around the considered voxel.