Ultrasonic techniques are becoming increasingly important in medicine, both as a diagnostic took and as a therapeutic modality. Although, ultrasound has been in medicine since the 1930's, it is only recently that these techniques have been widely used and their potential fully recognized. Medical ultrasonic is now in a period of rapid growth and is on the verge of making a significant impact on clinical medicine. The field provides challenging and important engineering problems, which are unique to medicine and biology. It is an open proving ground to many techniques developed for other applications and gives inspiration to the development of new technological advances. This review outlines some of the basic principles of ultrasonics, discusses the acoustical properties of biological tissues, provides a historical perspective of the use of ultrasound in medicine, describes ultrasonic techniques presently
used in the clinic as well as those now under development, and reports on the standardization of medical ultrasonic procedures and measurements.