The thrust of this project has been to develop high resolution electromagnetic (EM) models that may be used to calculate absorbed energy and its distribution for near-field; whole-body or partial-body exposure conditions. This information is needed in the assessment of safety in the electromagnetic workplace and for patient and operator safety for the expanding biomedical applications of EM energy. During the previous project period we have developed a 3-D, anatomically-realistic impedance model of the human torso which has been used to obtain specific absorption rates (SARs) for a number of situations; namely, leakage magnetic fields from an induction heater, capacitor- and magnetrode -type applicators for cancer therapy and radio frequency (RF) magnetic fields used for NMR imaging. The experimental work on quantification of RF-induced currents in a human has pointed to the extremely high SARs that will result in the ankle cross section at the electric fields recommended in the RF Safety Guideline of the American National Standards Institute. This finding is likely to have an impact on the RF safety standards in the US and elsewhere. In requesting renewal of this project we plan to extend the impedance model to cover the whole human body including a finer subdivision of the regions of the hot spots. The improved model will be used for calculation of SAR distributions, for plane-wave, grounded and ungrounded exposure conditions; for operator safety with RF dielectric sealers; for patient and operator safety for a variety of applicators used in RF hyperthermia and for short-wave diathermy; for RF EM fields used for NMR imaging, etc.
|Gandhi, O P; Wu, D; Chen, J Y et al. (1997) Induced current and SAR distributions for a worker model exposed to an RF dielectric heater under simulated workplace conditions. Health Phys 72:236-42|
|Gandhi, O P; Gao, B Q; Chen, J Y (1992) A frequency-dependent finite-difference time-domain formulation for induced current calculations in human beings. Bioelectromagnetics 13:543-55|
|Chen, J Y; Gandhi, O P (1992) Numerical simulation of annular-phased arrays of dipoles for hyperthermia of deep-seated tumors. IEEE Trans Biomed Eng 39:209-16|
|Chen, J Y; Gandhi, O P (1989) RF currents induced in an anatomically-based model of a human for plane-wave exposures (20-100 MHz). Health Phys 57:89-98|
|Orcutt, N; Gandhi, O P (1988) A 3-D impedance method to calculate power deposition in biological bodies subjected to time varying magnetic fields. IEEE Trans Biomed Eng 35:577-83|
|Zhu, X L; Gandhi, O P (1988) Design of RF needle applicators for optimum SAR distributions in irregularly shaped tumors. IEEE Trans Biomed Eng 35:382-8|
|Gandhi, O P; Chen, J Y; Riazi, A (1986) Currents induced in a human being for plane-wave exposure conditions 0-50 MHz and for RF sealers. IEEE Trans Biomed Eng 33:757-67|