Analysis of energy coupling into spheroidal ferritic implants for hyperthermia applications

Author

Cottis, P.G. ; Melas, A.I. ; Uzunoglu, N.K.

Author_Institution

Dept. of Electr. Eng., Nat. Tech. Univ. of Athens, Greece

Volume

38

Issue

9

fYear

1990

fDate

9/1/1990 12:00:00 AM

Firstpage

1259

Lastpage

1267

Abstract

The coupling of energy of RF power into lossy tissues using a needle-shaped ferromagnetic implant excited by an externally applied current loop is analyzed theoretically. The ferritic implant is assumed to be of prolate spheroidal shape, while the tissue medium is modeled as a lossy sphere. The electromagnetic fields inside the ferritic implant, the surrounding lossy tissue, and the free space are appropriately expressed in terms of spherical and spheroidal wave functions. Application of the boundary conditions results in an infinite system of equations for the unknown field expansion coefficients. This system is truncated and solved and the electromagnetic field is computed numerically. Absorbed power density inside the implant and the surrounding medium is computed, and the efficiency of the method in producing in-depth energy deposition is examined

Keywords

biothermics; RF power; absorbed power density; boundary conditions; efficiency; electromagnetic fields; energy coupling; externally applied current loop; field expansion coefficients; hyperthermia applications; in-depth energy deposition; infinite system of equations; lossy sphere; lossy tissues; needle-shaped ferromagnetic implant; prolate spheroidal shape; spheroidal ferritic implants; spheroidal wave functions; Boundary conditions; Electromagnetic fields; Equations; Heating; Humans; Hyperthermia; Implants; Radio frequency; Shape; Wave functions;

fLanguage

English

Journal_Title

Microwave Theory and Techniques, IEEE Transactions on

Publisher

ieee

ISSN

0018-9480

Type

jour

DOI

10.1109/22.58652

Filename

58652