Calculation of the SAR Induced in Head Tissues Using a High-Order DGTD Method and Triangulated Geometrical Models

The great majority of numerical calculations of the specific absorption rate (SAR) induced in human tissues exposed to microwaves are performed using the finite difference time-domain (FDTD) method and voxel-based geometrical models. The straightforward implementation of the method and its computational efficiency are among the main reasons for FDTD being currently the leading method for numerical assessment of human exposure to electromagnetic waves. However, the rather difficult departure from the commonly used Cartesian grid and cell size limitations regarding the discretization of very detailed structures of human tissues are often recognized as the main weaknesses of the method in this application context. In particular, interfaces between tissues where sharp gradients of the electromagnetic field may occur are hardly modeled rigorously in these studies. We present here an alternative numerical dosimetry methodology which is based on a high order discontinuous Galerkin time-domain (DGTD) method and adapted geometrical models constructed from unstructured triangulations of tissue interfaces, and discuss its application to the calculation of the SAR induced in head tissues.

[1]  K. Yee.  Numerical solution of initial boundary value problems involving maxwell's equations in isotropic media , 1966 .

[2]  P. George,et al.  Automatic mesh generator with specified boundary , 1991 .

[3]  L. Paul Chew,et al.  Guaranteed-quality mesh generation for curved surfaces , 1993, SCG '93.

[4]  William E. Lorensen,et al.  Marching cubes: a high resolution 3D surface construction algorithm , 1996 .

[5]  Carey M. Rappaport,et al.  FDTD verification of deep-set brain tumor hyperthermia using a spherical microwave source distribution , 1996 .

[6]  J. Camart,et al.  Modeling of various kinds of applicators used for microwave hyperthermia based on the FDTD method , 1996 .

[7]  Vipin Kumar,et al.  Parallel Multilevel k-way Partitioning Scheme for Irregular Graphs , 1996, Proceedings of the 1996 ACM/IEEE Conference on Supercomputing.

[8]  Joe Wiart,et al.  A subgridding scheme based on mesh nesting for the FDTD method , 1999 .

[9]  Vipin Kumar,et al.  Parallel Multilevel series k-Way Partitioning Scheme for Irregular Graphs , 1999, SIAM Rev..

[10]  James C. Lin,et al.  Computer simulation and experimental studies of SAR distributions of interstitial arrays of sleeved-slot microwave antennas for hyperthermia treatment of brain tumors , 2000 .

[11]  S. Pisa,et al.  Specific absorption rate and temperature increases in the head of a cellular-phone user , 2000 .

[12]  Pascal Frey,et al.  YAMS A fully Automatic Adaptive Isotropic Surface Remeshing Procedure , 2001 .

[13]  Amir Yefet,et al.  A staggered fourth-order accurate explicit finite difference scheme for the time-domain Maxwell's equations , 2001 .

[14]  S. Pisa,et al.  Power absorption and temperature elevations induced in the human head by a dual-band monopole-helix antenna phone , 2001, IMS 2001.

[15]  J. Hesthaven,et al.  Convergent Cartesian Grid Methods for Maxwell's Equations in Complex Geometries , 2001 .

[16]  J. Hesthaven,et al.  Staircase-free finite-difference time-domain formulation for general materials in complex geometries , 2001 .

[17]  O. Gandhi,et al.  Temperature rise for the human head for cellular telephones and for peak SARs prescribed in safety guidelines , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[18]  Chi Hou Chan,et al.  An explicit fourth-order orthogonal curvilinear staggered-grid FDTD method for Maxwell's equations , 2002 .

[19]  J. Hesthaven,et al.  Nodal high-order methods on unstructured grids , 2002 .

[20]  James D. Westwood.  Medicine meets virtual reality 11 : NextMed : health horizon , 2003 .

[21]  Jan S. Hesthaven,et al.  High-order accurate methods in time-domain computational electromagnetics: A review , 2003 .

[22]  Y. Rahmat-Samii,et al.  Implanted antennas inside a human body: simulations, designs, and characterizations , 2004, IEEE Transactions on Microwave Theory and Techniques.

[23]  Qing Huo Liu,et al.  A Staggered Upwind Embedded Boundary (SUEB) method to eliminate the FDTD staircasing error , 2004, IEEE Transactions on Antennas and Propagation.

[24]  Steve Oudot,et al.  Provably good sampling and meshing of surfaces , 2005, Graph. Model..

[25]  L. Fezoui,et al.  Convergence and stability of a discontinuous galerkin time-domain method for the 3D heterogeneous maxwell equations on unstructured meshes , 2005 .

[26]  T. Fouquet,et al.  Conservative space-time mesh refinement methods for the FDTD solution of Maxwell's equations , 2006 .

[27]  Gary Cohen,et al.  A spatial high-order hexahedral discontinuous Galerkin method to solve Maxwell's equations in time domain , 2006, J. Comput. Phys..

[28]  J. Wiart,et al.  Variability analysis of SAR from 20 MHz to 2.4 GHz for different adult and child models using finite-difference time-domain , 2008, Physics in medicine and biology.

[29]  H. Fahs.  Development of a hp-like discontinuous Galerkin time-domain method on non-conforming simplicial meshes for electromagnetic wave propagation , 2009 .

[30]  Stéphane Lanteri,et al.  An implicit discontinuous Galerkin time‐domain method for two‐dimensional electromagnetic wave propagation , 2010 .

[31]  Stéphane Lanteri,et al.  Locally implicit discontinuous Galerkin method for time domain electromagnetics , 2010, J. Comput. Phys..