A Partially Ferrites Loaded Waveguide Applicator for Local Heating of Tissues

Yoshio NIKAWA  Yasunori TOYOFUKU  Fumiaki OKADA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E78-B   No.6   pp.836-844
Publication Date: 1995/06/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Medical Applications of Electromagnetic Techniques)
Category: 
Keyword: 
microwave hyperthermia,  ferrites loaded waveguide,  waveguide applicator,  microwave heating,  heating pattern control,  

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Summary: 
A partially ferrites and dielectric loaded water filled waveguide applicator is presented which can be used for microwave heating of tissues. The applicator can change its heating pattern by changing the external DC magnetic field applied to the ferrites. The electromagnetic (EM) field distribution inside the applicator is obtained theoretically and the simulated EM field inside the applicator is checked experimentally using 430MHz. Furthermore, on the basis of the EM field distribution inside the applicator, simulations of SAR distribution inside lossy homogeneous human tissue as muscle are performed using finite difference time domain (FD-TD) method. Simulated data of Specific Absorption Rate (SAR) distribution is compared with the experimental ones. Simulations of temperature distribution are also performed using heat transfer equation. Simulated data of temperature elevation distribution is compared with the experimental ones. The simulated results agree well with the experimental ones and it is confirmed that the heating pattern can be changed by external DC magnetic field applied to the applicator. The results obtained here show that the partially ferrites and dielectric loaded water filled waveguide applicator which operates at 430 MHz can change its heating pattern without changing its setup and can heat local target on the human body for hyperthermia treatment.