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Numerical electromagnetic techniques for dosimetry and biomedical applications.

机译：剂量学和生物医学应用的数字电磁技术。

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摘要

(EM) fields are increasingly being used for many new and rapidly expanding applications. Along with the growing applications of EM fields, increasingly sophisticated modeling, experimental and modeling techniques have been developed for evaluating and understanding the biological interaction of human tissues and body with EM fields. In this dissertation, we expanded the use of these EM techniques to some new and novel dosimetric and biomedical applications in the following four subjects: (1) We developed a broadband waveguide-based experimental setup and numerical procedures using FDTD method to determine the peak 1- and 10-g SARs, and designed a validation system for the SAR measurement system and/or for E-field probe calibration for the 802.11a frequency band 5.15 to 5.825 GHz. (2) We presented a numerical procedure for compliance testing of EAS systems with ferromagnetic cores, which utilizes the duality of magnetic and electric circuits and a procedure based on three-dimensional (3-D) admittance method to calculate the magnetic fields exposure of such devices. (3) We solved the bioheat equation for anatomically based thermal models of the human heads to determine the heating of various tissues due to EM radiation of typical cellular telephones. Also investigated are the thermal implications of the SAR limits suggested in the various safety guidelines and the relationships between brain temperature elevations and the various 1- and 10-g SARs. (4) MEG and its inversion techniques have a great potential in the noninvasive characterization of brain function and activities. Many reconstruction approaches employ ECDs (Equivalent Current Dipoles) for modeling highly localized stimuli-induced neural current sources in the brain and head shapes modeled with single or multiple concentric spheres for the forward problem. In this thesis, we used a shaped head model and 3-D impedance method to calculate the forward magnetic fields so that the inversion algorithm is based on a more accurate lead field matrix. A statistically-averaged approach of Tikhonov regularization and FOCUSS (FOCal Underdetermined System Solution) iterations were applied to forward-calculation "measurement" data corrupted by high level Gaussian noise (Signal-to-Noise Ratio as low as 2), to locate two to four possible ECDs in the brain with high accuracy.
机译：（EM）领域正越来越多地用于许多新的且快速扩展的应用程序。随着电磁场的不断增长的应用，已开发出越来越复杂的建模，实验和建模技术，用于评估和理解人体组织和人体与电磁场的生物相互作用。在本文中，我们将这些EM技术的应用扩展到以下四个主题的一些新颖的剂量学和生物医学应用中：（1）我们开发了一种基于宽带波导的实验装置和使用FDTD方法确定峰1的数值程序。 -和10 g SAR，并为SAR测量系统和/或用于5.15至5.825 GHz 802.11a频带的电场探头校准设计了验证系统。 （2）我们提出了利用铁磁芯的EAS系统进行顺应性测试的数值程序，该程序利用了磁路和电路的双重性，并基于三维（3-D）导纳方法计算了此类磁场的暴露量。设备。 （3）我们解决了基于人体头部的解剖学热模型的生物热方程，以确定由于典型蜂窝电话的EM辐射而导致的各种组织的发热。还研究了各种安全指南中建议的SAR极限的热影响，以及脑温升高与各种1 g和10 g SAR的关系。 （4）MEG及其反转技术在脑功能和活动的非侵入性表征中具有巨大潜力。许多重建方法都采用ECD（等效电流偶极子）来对大脑和头部形状中高度局限的刺激诱发的神经电流源进行建模，并用单个或多个同心球为正向问题建模。在本文中，我们采用了成形头模型和3-D阻抗方法来计算正向磁场，从而使反演算法基于更精确的引线场矩阵。将Tikhonov正则化和FOCUSS（FOCal欠定系统解决方案）迭代的统计平均方法应用于被高斯高斯噪声（信噪比低至2）破坏的前向计算“测量”数据，以找到两个大脑中四种可能的ECD的准确性很高。

著录项

  • 作者

    Li, Qingxiang.;

  • 作者单位

    The University of Utah.;

  • 授予单位 The University of Utah.;
  • 学科 Engineering Biomedical.; Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 159 p.
  • 总页数 159
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;无线电电子学、电信技术;
  • 关键词

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