An advanced boundary element method (BEM) implementation for the forward problem of electromagnetic source imaging

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2004-11-07

Author

Akahn-Acar, Z
Gençer, Nevzat Güneri

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The forward problem of electromagnetic source imaging has two components: a numerical model to solve the related integral equations and a model of the head geometry. This study is on the boundary element method (BEM) implementation for numerical solutions and realistic head modelling. The use of second-order (quadratic) isoparametric elements and the recursive integration technique increase the accuracy in the solutions. Two new formulations are developed for the calculation of the transfer matrices to obtain the potential and magnetic field patterns using realistic head models. The formulations incorporate the use of the isolated problem approach for increased accuracy in solutions. If a personal computer is used for computations, each transfer matrix is calculated in 2.2 h. After this pre-computation period, solutions for arbitrary source configurations can be obtained in milliseconds for a realistic head model. A hybrid algorithm that uses snakes, morphological operations, region growing and thresholding is used for segmentation. The scalp, skull, grey matter, white matter and eyes are segmented from the multimodal magnetic resonance images and meshes for the corresponding surfaces are created. A mesh generation algorithm is developed for modelling the intersecting tissue compartments, such as eyes. To obtain more accurate results quadratic elements are used in the realistic meshes. The resultant BEM implementation provides more accurate forward problem solutions and more efficient calculations. Thus it can be the firm basis of the future inverse problem solutions.

Subject Keywords

Radiological and Ultrasound Technology, Radiology Nuclear Medicine and imaging

URI

https://hdl.handle.net/11511/37908

Journal

PHYSICS IN MEDICINE AND BIOLOGY

DOI

https://doi.org/10.1088/0031-9155/49/21/012

Collections

Department of Electrical and Electronics Engineering, Article

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Citation Formats

Z. Akahn-Acar and N. G. Gençer, “An advanced boundary element method (BEM) implementation for the forward problem of electromagnetic source imaging,” PHYSICS IN MEDICINE AND BIOLOGY, pp. 5011–5028, 2004, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/37908.