Versatility of distributed focus ultrasound in treatment of superficial lesions.

In order to study the efficacy of hyperthermia as a cancer treatment modality, it is important to be able to define the specific volume being raised to hyperthermic temperatures corresponding to the selected method of heating. Measurements have been made of temperature distributions in rat mammary tumors during steady state heating with annular focused ultrasound (2.0 MHz). Biological response in terms of growth inhibition is compared with uniformity of induced temperature throughout the tumors as a function of annular focusing dimensions.