In our previous study, a non-invasive heating method was proposed which could utilize a re-entrant type resonant cavity applicator for deep-seated tumors. For the first time, a prototype heating system using a cylindrical resonant cavity applicator was developed, and results from the experimental heating of agar phantoms and animals were discussed. In the proposed method, as a whole human body was set in the cylindrical resonant cavity applicator to heat the targeted area, there was a risk of heating healthy human tissues.

In the present paper, a new method using a rectangular resonant cavity is proposed to non-invasively heat the targeted area without physical contact to the subject. Dimensions of the rectangular resonant cavity applicator were 60 cm in height, 70 cm in width and 20 cm in length. In this method, since the targeted area is placed inside the rectangular resonant cavity applicator, the risk of heating the healthy tissue is minimized.

Here, the measured temperature distributions of the heated agar phantom with the developed system was described. First, a setup of the proposed resonant cavity applicator was presented. Second, the results of heating human shaped agar phantom were presented. Finally, the results of computer simulations and experiments with the developed prototype heating system were discussed.

From these results, it was found that the proposed rectangular resonant cavity applicator could be useful in controlling a small heated area without contact to the human body, and could be applicable for treating various tumors.