An RF hyperthermia electrode which generates no edge effect.

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Author(s): N. Uchida, M. Moriyama, A. Kawaguchi, M. Yokokawa, S. Ikeda, H. Kitagaki, H. Kato; Shimane University, Izumo, Japan; Okayama University, Okayama, Japan



Background: For local hyperthermia cancer therapy, radio frequency (RF) capacitive heating with a pair of electrodes is one of the most effective methods. RF hyperthermia with a conventional 2-dimensional square plate electrode produces an 'edge effect' - the focusing of the RF current resulting in focal overheating. We designed and propose a novel hemispherical-shaped RF capacitive heating electrode that generates no edge effect.


Methods: A CAD simulation (COMSOL Multiphysics 3.4) was done, and current and specific absorbance ratio (SAR) distributions of both the hemispherical and the conventional square plate shape electrodes were obtained by a 3-D finite element method.


Results: The hemispherical electrode generated no focusing of current distribution, nor overheating with SAR elevation, while the square plate electrode produced an edge effect with local SAR elevation.


Conclusions: The hemispherical electrode showed no edge effect from focal overheating. Our new electrode may be useful for local heating in the oral or vaginal cavity in clinical use. Phantom studies with a prototype electrode should be carried out for further confirmation.