Some Recent Applications of FDTD for EM Dosimetry: ELF to Microwave Frequencies
For short nanosecond pulses with ultrawide bandwidths, a frequency-dependent FDTD has been formulated, which uses frequency-variable properties of the various tissues using the best-fit two-relaxation-constant Debye equations.
The FDTD code has been modified and used for specific absorption rate (SAR) calculations for radiofrequency (RF) magnetic fields typical of new and emerging magnetic resonance imaging (MRI) techniques.
Using scaled higher quasi-static frequencies, the FDTD method has been used for calculations of internal fields and induced current densities in an anatomically based model of the human body for electric, magnetic, or combined electromagnetic (EM) fields at power-line frequencies.
We also describe a new convolution method to alleviate the problem of having to run computer-memory-intensive anatomically based models repeatedly as the incident fields are varied in time and/or space domains. In this method, the impulse response of the heterogeneous model in time and space domains is obtained and stored. This may then be convolved with the prescribed time and/or space variations of the incident fields. Since convolution integrals are relatively easy to calculate and do not need a large computer memory, high-resolution dosimetric calculations should be possible using smaller computers or PCs.
KeywordsSpace Domain Electromagnetic Pulse Incident Field Heterogeneous Model Microwave Theory
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