Numerical Methods

  • Om P. Gandhi


Knowledge of the SAR and temperature distributions in the human body in response to electromagnetic exposures is of basic interest in the assessment of biological effects and medical applications of electromagnetic energy. Several methods have been described in the literature for numerical calculations of SAR distributions (Taflove and Brodwin, 1975b; Chen and Guru, 1977; Hagmann et al., 1979). While experiments must be done to verify the accuracy of any theoretical procedure, the numerical methods do allow a detailed modeling of the anatomically-relevant inhomogeneities for a human that are not easy to model experimentally. A couple of excellent review articles summarize the status of the field (Durney, 1980; Spiegel, 1984), though these are somewhat outdated at the present time. Maxwell’s equations have been solved in both the integral and differential equation form for the distribution of electric and magnetic fields and mass-normalized rates of energy deposition (specific absorption rates or SARs). For temperature calculations the bioheat equation is solved for a cylindrical thermal model where the human body is represented by six cylindrical segments for the head, torso, arms, hands, legs and feet (Stolwijk, 1970; Stolwijk and Hardy, 1977 and Stolwijk, 1980). Each segment consists of four concentric cylinders representing layers of skin, fat, muscle and core tissue. Recognizing that such formulations are incapable of properly accounting for the painstakingly-obtained SAR distributions, we have developed an inhomogeneous thermal block model of man using heterogeneous thermal properties obtained from the anatomic data for 476 cells (Chatterjee and Gandhi, 1983). Since SARs are now available with a higher degree of resolution than ever in the past, a 5432-cell inhomogeneous thermal model of the human body has also been developed recently (Gandhi and Hoque — to be published).


Impedance Method Microwave Theory Incident Plane Wave Specific Absorption Rate FDTD Method 
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Copyright information

© Plenum Press, New York 1989

Authors and Affiliations

  • Om P. Gandhi
    • 1
  1. 1.Electrical Engineering DepartmentUniversity of UtahSalt Lake CityUSA

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