Heating system with a lens applicator for 430 MHz microwave hyperthermia.

To attain deep and localized heating for hyperthermic treatment of cancers, metal plate lens applicators that can converge microwave electromagnetic (EM) energy in the lossy medium such as human muscle with a computer-controlled heating system have been developed. This paper describes a system operating at 430 MHz. Results of an electric-field distribution calculation and a heating experiment made on a saline solution phantom show that the maximum heating depth is over 60 mm using the lens applicator, which is twice as deep as that obtained with a conventional waveguide applicator. The experimental results agree well with the theoretical ones. A computer-controlled heating system has been developed using the applicator. Experimental results show that fluctuations in temperature at locations in the heating region of the saline phantom were maintained within +/- 0.3 degrees C of the present temperatures. These results indicate that the system can be used for the clinical hyperthermia treatment of cancer.