A Combined Electromagnetic and Thermal Analysis of Current Sheet Hyperthermia Applicators

Abstract

In this contribution we present results for a combined electromagnetic and thermal model which calculates the three-dimensional time-temperature distributioln as a1function of electromagnetic energy dissipation. In this paper an enhanced version of the Finite-Difference Time-Domain (FDTD) method is used in conjunction with a heat transfer model specifitally for the thermal analysis of current sheet hyperthermia applicators. However, the general algorithm is applicable; to a wide range of industrial, scientific, medical and communication applications which involve high frequency electromagnetic waves.

Coupled thermal-electromagnetic model for microwave heating of temperature-dependent dielectric media

“…where the Kernel is given by (13) The solution for the inhomogeneous problem (11) is (14) The time dimension is discretized in order to solve the coupled microwave-heating problem iteratively. The temperature distribution found in each iterative step is used as an initial condition for the successive step in (12).…”

“…Each layer is characterized by parameters of diffusion coefficient, density, and specific heat. The microwave heat production results in the evolution of the local temperature For the numerical simulation, (13) and (16) are discetized in space and time, and (17) is solved numerically. The expressions are used in Section III to simulate microwave heating processes in various conditions.…”

“…In FDTD methods, the partial differential equations are substituted by a set of difference equations. FDTD methods have been used to solve two-dimension [7], [13], [20], [21] and three-dimension 0093-3813/99$10.00 © 1999 IEEE [8], [10], [11], [20], [22] configurations. Ray-tracing methods are used for millimeter-wave heathing models [23].…”

“…Typically, three iterative steps are used to solve the coupling between the EM and thermal processes [4], [5], [7], [8], [10], [12], [13], [15]- [18]. First, the EM propagation in the medium is calculated.…”

“…In order to reduce the needs for these resources, algorithms use the diffused time-scale assumption. According to this assumption, the EM field attains a steady state [4], [5], [7], [8], [13], [16], [18], and therefore its time scale is much smaller than the heat diffusion. Other approximations reduce computation by temperature-distribution correction methods [7].…”