The proposed work seeks to continue development of a new generation of commercial ultrasound applicators and associated hardware/software capable of improved heating uniformity and controllability at various depths within the body, with specific application to thermal therapy for breast cancer and chest wall recurrence. These new applicator designs are based on extensive clinical experience with the SONOTHERM 1000 multichannel ultrasound hyperthermia system now in clinical use at over 36 sites around the world, as well as earlier Phase I studies. The goal of Phase II is to construct and test applicators and control software specifically for use with the SONOTHERM-TM system which offer (a) higher frequency operation to limit penetration depth where indicated; (b) simultaneous dual frequency operation to provide depth of penetration control over the face of the ultrasound applicator array; and (c) improved means for coupling these new applicators for breast and chest wall treatments. Since development of electronic hardware modifications to implement simultaneous dual frequency operation was completed in Phase I, the present effort will be focused on the implementation of the new applicators and control software, and to their pre-clinical testing. PROPOSED COMMERCIAL APPLICATION: There is presently a resurgence of interest in hyperthermia which is spreading world wide owing to recent reports in Europe of favorable results of randomized trials. With about 2800 cancer therapy sites worldwide, a small number of active clinical hyperthermia sites, the full potential of this therapy has yet to be realized. FDA Pre-Market Approval, and recognized advanced technology, favorably positions Labthermics to benefit from the increased awareness of the effectiveness of modern hypothermia therapy.