Unstructured mesh generation for modelling human exposure to electromagnetic fields </head> <body> <h1>Unstructured mesh generation for modelling human exposure to electromagnetic fields </h1> <hr> <DL> <DT> <B>Where : </B> <BR> <DD> <B> <a href="http://www.inria.fr"> INRIA </a>,<A href="http://www-sop.inria.fr/"> Unité de Sophia Antipolis</A> </B> <BR> Team <a href="http://www-sop.inria.fr/geometrica/"> Geometrica </a> and <a href="http://www-sop.inria.fr/geometrica/"> Caiman </a> <BR> BP 93 <BR> 06902 <A HREF="http://pubweb.parc.xerox.com/map/border=1/color=1/grid=0/ht=25.00/lat=43.70/lon=7.25/mark=43.73,7.28/proj=rect/river=1/wd=70.00?258,130"> Sophia Antipolis </A> <BR> FRANCE <BR> <BR> <DT> <B>Information:</B> <BR> <DD> <TABLE WIDTH=100%> <TR ALIGN=TOP> <TD><A HREF="http://www-sop.inria.fr/geometrica/team/Mariette.Yvinec/"> <B> Mariette Yvinec</B> </a> <B> Tel :</B> +33 4 92 38 77 49 <B>e-mail:</B> <A HREF="mailto:Mariette. Yvinec@sophia.inria.fr"><Mariette.Yvinec@sophia.inria.fr></A> <BR> <A HREF="http://www-sop.inria.fr/caiman/team/Stephane.Lanteri "> <B> Stéphane Lantéri </B></a> <B> Tel :</B> +33 4 92 38 77 34 <B>e-mail:</B> <A HREF="mailto:Stephane.Lanteri@sophia.inria.fr"><Stephane.Lanteri@sophia.inria.fr></A> </TD> </TABLE> </DL> <hr> <DL> <DT> <B> Description:</B> <DD> Beside industrial applications (both civilian and military), computer simulation of electromagnetic wave propagation is nowadays increasingly applied to societal questions. Of particular interest is the area concerned with the interaction of electromagnetic wave with humans or, more precisely, living tissues. There are at least two situations that are concerned with this subject: the study of potential adverse effects of electromagnetic waves and, the use electromagnetic waves for medical applications. A classical example in relation with the first point is the study of the propagation of an electromagnetic wave emitted by a mobile phone in the tissues of the user head. <p> Biological effects of mobile phone radiation radiation have been investigated both from the experimental and numerical viewpoints. Concerning numerical modeling, the power absorption in a user head is computed using discretized models built from clinical MRI (Magnetic Resonance Images) data. The great majority of such numerical studies have been conducted using the Finite Difference Time Domain (FDTD) method which is based on structured (catesian) meshes for solving the Maxwell equations. Due to the possible straightforward implementation of the algorithm and the availability of computational power, FDTD is currently the leading method for numerical assessment of human exposure to electromagnetic waves. However, the FDTD method still suffers from limitations. Most of those limitations come from the use of rectilinear uniform grids which, within reasonable size, fail to modelize very detailed structures of head tissues that may be essential for reliable compliance testing. So far, little attention has been put to the application of numerical methods able to deal with unstructured meshes that is, FETD Finite Element Time Domain) and FVTD (Finite Volume Time DomainD) methods. <p> Unstructured mesh based numerical methods were at the heart of the <a href="http://www-sop.inria.fr/caiman/personnel/Stephane.Lanteri/headexp/headexp.html"> HeadExp </a> cooperative research action of INRIA, that started on January 2003 for a duration of 2 years. This project aimed at filling the gap between medical images of the head and the efficient and accurate numerical modeling of the interaction of electromagnetic waves emitted by mobile phones with biological tissues. This has required the development of specific image analysis tools and automated unstructured mesh generation tools for the construction of realistic discretized human head models based on unstructured, locally refined, tetrahedral meshes. For this purpose, the HeadExp project involved specialists of medical image processing, geometrical modeling and numerical modeling. The Caiman and Geometrica project-teams have taken part to the HeadExp project <p> The accomplishments of the HeadExp project [scarella-etal:05] have clearly demonstrated the benefits of using unstructured mesh based numerical methods for numerical dosimetry studies of electromagnetic waves. However they have also raised a number of issues that motivate further investigations especially for what concern the construction of geometrical models. In particular, two points deserve attention: a) the simultaneous generation of surfacic (triangular) and volumic (tetrahedral) meshes for several tissues (e.g skin, external and internal skull, brain, etc.) with different resolutions. b) the local refinment of volumic meshes. <p> This subject proposes to run further investigations on unstructured mesh generation from medical imaging data. The goal would be in a first step to improve the numerical models of the head obtained in the HeadExp project and then to obtain reliable numerical models of the whole human body taking into account different tissues. Those studies will be perform using the mesh generation tool provided by the library CGAL. Based on Delaunay refinement, this unstructed mesh generation tool offers wide possibilities for the handling of several surfaces in the volume to be meshed and the respect of non uniform sizing field [oudot-etal:05]. The tool is able to work on three dimensional images resulting from medical imaging data. This tool is a powerfull, recently developped tool and its use in such a project would contribute to its final tuning. <BR><BR> <DT><B>Tools : </B> <DD> PC Linux, <BR> langage C++, <br> Bibliothèque géométrique <A HREF="http://www.cgal.org"> CGAL</A> <BR> <BR><BR> <DT><B> Bibliography :</B> <DD> <UL> <LI> Geometry and Topologie for mesh generation. Herbert Edelsbrunner, Cambridge university press, 2001 <li> J. D. Boissonnat and S. Oudot. Provably good surface sampling and approximation. Proceedings of International Symposium on computational Geometry (2003). <li> Meshing Volumes Bounded by Smooth Surfaces. Steve Oudot, Laurent Rineau and Mariette Yvinec. Proc. 14th International Meshing Roundtable, 2005, pp 203-219 <li> [scarella-etal:05] G. Scarella and O. Clatz and S. Lanteri and G. Beaume and S. Oudot and J.-P. Pons and S. Piperno and P. Joly and J. Wiart. Realistic numerical modeling of human head tissues exposure to electromagnetic waves from mobiles phones. 7th International Conference on Mathematical and Numerical Aspects of Wave Propagation, Brown University, Rhode Island, USA, June 20-24, 2005. </UL> </DL> <BR><BR> <A HREF="./"> <I> Retour aux autres stages</I></A> <p> <address><a href="mailto:yvinec@moustique.inria.fr">Mariette Yvinec</a></address>   Last modified: Thu Mar 2 09:21:53 CET 2006  </body> </html> --------------070809020007010305090803--