| Parkinson's disease (PD) is a common neurodegenerative disease. The clinical signs of PD include resting tremor, bradykinesia, rigidity, and postural instability. Because of its reversibility and adjustability, deep brain stimulation (DBS) has become a widely accepted and recognized treatment for PD patients. However, in despite of the well known clinical effect, the mechanism under action of DBS is still under investigation. This thesis constructed the finite element model of DBS to study the electric distribution of deep brain electrode areas.In this thesis, a three-dimensional realistic head model are reconstructed with two layers including the head and brain based on MRI medical image data and mesh system is created for DBS analysis. Firstly, the cranial MR images are processed by MIMICS software for image segmentation and 3D reconstruction. Then the 3D surface model is imported into Geomagic Studio software to generate three-dimensional solid model. Finally, the finite element model is constructed including the two layers with the realistic head and brain tissue using COMSOL Multiphysics software. The three-dimensional numerical model of head is applied to numerical calculation, and it is a foundation for the electric field analysis of DBS. At the end, we made use of the 3D model constructed the DBS model with COMSOL, and analyzed the distribution of electric field based on the principle of DBS at deep brain electrodes area by monopolar stimulation and bipolar stimulation, respectively. Compare the electric filed distribution of four layers concentric sphere to that of real head model, the results show the consistent electric distribution at deep brain electrodes area by monopolar stimulation and bipolar stimulation, respectively. At the same time, we analyzed the effect of the electrode contact spacing on the electric field in the brain tissue by the bipolar stimulation, it will useful to provide a theoretical basis for clinical application of DBS. |
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