Dielectric properties of body tissues

The need for extensive data on the dielectric properties of human tissues is often and strongly felt among scientists and researchers involved in the interactions of electromagnetic (EM) fields and biological systems. Numerical dosimetry, for instance, (the discipline devoted to calculate, by means of numerical algorithms, current densities and specific absorption rates (SARs) in tissues and organs of individuals exposed to EM fields) deals with digitized 2D or 3D human models each element of which (pixel in 2D and voxel in 3D models) has to be recognized as being constituted by a given, well defined tissue and thus must have assigned unique dielectric properties, consisting of a pair of values, one for the relative permittivity and one for the electrical conductivity at each frequency of interest. This application is aimed to calculate the dielectric properties of human body tissues in the frequency range from 10 Hz to 100 GHz using the parametric model and the parameter values developed by C.Gabriel and collegues (see Credits and References below). It is based on a client-server approach. The server program runs in background on a central system and is responsible for the management of the parameter database (14 parameters for each defined tissue) and for the calculation of the dielectric properties of requested tissues at requested frequencies. These properties comprise the relative permittivity, the electrical conductivity and a few significant derived quantities: the loss tangent, the wavelength and the penetration or "skin" depth. The client program is executed by the user on a remote system connected to the server by a Local or a Wide Area Network supporting the TCP/IP protocol; the client program implements the user interface and translates user requests into commands for the server; it also has to deal with reception and display of the requested data. The main advantage of the client/server approach consists in the centralized management of the tissue parameters, allowing new tissues to be defined or parameter values to be changed without having to redistribute software to the users. The users, on their sides, get also rid of the need to implement the code for the calculation of the dielectric properties from the parameter values. The availability of the server documentation makes it possible, for users who need it and can afford it, to develop their own applications devoted to specific tasks or platforms. The reverse of the medal obviously is the need of a TCP/IP link between the client and the server.