Therapeutic ultrasound an overview.

Therapeutic ultrasound is defined as the use of ultrasound for the treatment of diseased or injured organs or bodily structures and is quite distinct from diagnostic ultrasound. There were many early attempts in the past to use ultrasound in therapy for a variety of applications and while some of these have not been pursued others have led on to clinical applications which are now used routinely. Such progress has been made possible by a number of factors including advances in transducer design, more accurate measurement and calibration of acoustic power and careful experiments to determine the precise nature of chemical processes taking place during and following the exposure of tissue to ultrasound. Major advances have been made in some fields where ultrasound is used such as physiotherapy, surgical instruments, chemotherapy, drug delivery and more recently, high intensity focused ultrasound (HIFU). The last of these has seen enormous activity leading to the formation of the International Society of Therapeutic Ultrasound and a number of very well attended regular specialist meetings. In this review some historical perspectives of therapeutic ultrasound and progress in the field since the early 1990's will be presented.