Heating characteristics of a 430 MHz microwave heating system with a lens applicator in phantoms and miniature pigs.

Heating experiments on phantoms and miniature pigs were performed using two types of lens applicator and a conventional waveguide applicator fed by a 430 MHz microwave heating system (HTS-100, manufactured by Tokyo Keiki Co., Ltd). Temperature distributions in agar phantoms and miniature pigs were measured at regular intervals during heating. The following results were thus obtained: (1) The effective heating depth varied with the focal length, showing the lens effect. (2) Using a four-aperture lens applicator in miniature pigs, a heating depth of 6 cm was obtained. This almost doubles the depth of conventional waveguide applicator. The heating area was 12 X 6 cm at the depth of 4 cm. (3) Dielectric properties of the buttocks of the miniature pig were virtually identical to those of the agar phantom containing 0.35% NaCl and 0.05% NaN3.