Present and Future Applications of Ultrasonics in Biomedicine

The current importance of ultrasonic energy for the investigation and modification of biological systems is reviewed and the immediately foreseeable potential apparent to the author is predicted. The uses of ultrasound in basic research studies of biological systems and medical applications are conveniently grouped into two major categories: passive uses, or those in which the acoustic field does not significantly modify either permanently or temporarily structure and/or function of the system, and active uses, or those in which modification of the system is the objective. Included within the first category are: absorption spectroscopy of solutions of macromolecular species, microscopy of cells and tissues, absorption characteristics of gross tissue, and visualization of soft tissue structure and its dynamics. The second category includes: the use of ultrasound in neuroanatomical and neurophysiological studies and the treatment of neurological disorders by the production of selective permanent or temporary changes in arrays of sites in the central nervous system, destruction of carcinogenic tissue, modification of endocrine glands, investigation of contractile and other properties of muscle, and the potentiation of ionizing radiation by simultaneous application of ultrasound. Applications of ultrasound in the biomedical field of a primarily technological nature are either mentioned only briefly or omitted entirely from the review. The "socioeconomic" factors which determine the level of financial support, and thus the rate of scientific progress, for a field are also briefly mentioned.