| Popis: |
We present work on the computational modeling of electromagnetically induced heating in the hyperthermic treatment of cancer using ∞uid-dispersed magnetic nanoparticles. Magnetic nanoparticle hyperthermia can be used as a complement to chemotherapy or for direct targeting and destruction of tumors through heat treatment. The ability of nanoscale materials to provide an extremely localized therapeutic efiect is a major advantage over traditional methods of treatment. When an AC magnetic fleld is applied to a ferro∞uid, Brownian rotation and Neel relaxation of induced magnetic moments result in power dissipation. In order to achieve appreciable volumetric heating, while maintaining safe values of frequency and magnetic fleld strength, and to reduce the risk of spot heating of healthy tissue, it is necessary to determine an ideal range of input parameters for the driving magnetic fleld as well as the complex susceptibility of the ferro∞uid. We do this by the coupling of the solution of Maxwell's equations in a model of the tumor and surrounding tissue as input to the solution to the Pennes' Bioheat Equation (PBE). In this study, we solve both sets of equations via the Finite Difierence Time Domain (FDTD) method as implemented in the program SEMCAD X (by SPEAG, Schmid & Partner Engineering). We use a multilayer model of the human head made up of perfused dermal and skeletal layers and a grey-matter region surrounding a composite region of tumor tissue and the magnetic nanoparticle ∞uid. The tumor/ferro∞uid composite material properties are represented as mean values of the material properties of both constituents, assuming homogeneity of the region. The AC magnetic excitation of the system (within 100kHz{2MHz frequency range) is provided by square Helmholtz coils, which provide a uniform magnetic fleld in the region of interest. The power density derived from the electromagnetic fleld calculation serves as an input term to the bioheat equation and therefore determines the heating due to the ferro∞uid. Results for several variations of input parameters will be presented. |
