Analysis of Temperature Distribution within the Human Body in Electromagnetic Hyperthermia

在这个研究项目中，对于非常实用的模型，完成了一个计算人体内电磁场和功率损失分布的算法，这些模型与由非均匀人体区域、水丸区域和波导多应用系统组成的真实模型几乎相同。在该算法中，完成了以下关键技术：1.有针对性地考虑了位于波列加速器内部的柱子的激励机制，以适应FD-TD分析。推导了适用于人体等有耗介质中吸收边界的新的吸收边界条件，并完成了在电磁波辐射功率损失以及人体内外各种冷却效应影响下，随时间变化的人体内温度分布的计算算法。该算法采用了隐式交替方向法，并且通过对各种数值结果的仔细检验，得到了一些新的结果。典型的是1。对于热疗多用器系统，TE(横电)波型应用系统优于TM(横磁)波型系统，因为前者比后者更好地集中了人体纵向的功率损耗分布。水丸剂应该在关注的加热区域附近的有限区域使用，因为水区域往往会不必要地扩大热区域。

In this research project, an algorithm has been completed for calculating electromagnetic fields and power loss distributions within the human body for very practical models which are almost the same as the real models consisting of inhomogeneous human body regions, water bolus regions and waveguide multi-applicator systems. In this algorithm, the following important techniques are accomplished :1. Excitation mechanism by a post situated inside the wavequide applicator is pertinently taken into account to accommodate itself to FD-TD analyzing.2. New absorbing boundary conditions are derived which are useful for the absorbing boundaries located in lossy media such as the human body regions.Also completed in the project is the algorithm for calculating the temperature distributions within the human body changing time-dependently under the influence of the power loss induced by electromagnetic wave irradiation as well as the influence of various cooling effects inherent in the human body and coming from outside the body. An Implicit Alternating Direction method is employed in this algorithm.Moreover, several new findings have been obtained from careful examinations of various numerical results. Typical ones are1. For the hyperthermia multi-applicator system, the TE(Transverse Electric)wave type applicator system is superior over the TM(Transverse Magnetic)wave type system, because better concentration of the power loss distribution in the longitudinal direction of the body is attained by the former system than the latter.2. The water bolus should be used in the limited region near around the heated regions of interest because the water region tends to expand the hot regions unnecessarily.