Physical aspects of ultrasound hyperthermia of the chest wall

Recent advances in the development of clinical ultrasound hyperthermia systems to treat superficially located cancerous volumes are presented, with emphasis on the treatment of tissues at high risk or with microscopic cancer, and of recurrent/persistent breast carcinoma on the chest wall. Recent advances in microwaves based systems are also discussed for comparison. In recent years the demand has been for specialized systems, site and disease specific, with a high degree of dynamic power deposition control. A system under development at our institution to allow the simultaneous or sequential delivery of ultrasound hyperthermia and external photon/electron beam radiation is described in detail. The optimization of the system design and key physical parameters to achieve controlled heating in highly acoustically, thermally and physiologically heterogeneous tissues are presented while highlighting the engineering challenges encountered. Both laboratory and numerical modeling data are presented. The major advances achieved are delineated and future R&D efforts proposed