ABSTRACT
You know from experience that sound travels through human tissue because you can hear a heartbeat simply by placing your ear against another person's chest. Medical diagnostic ultrasound imaging uses the body's transparency to sound to “see” within. Because of its safety, diagnostic ultrasound is the only imaging technology favored for routine use in obstetrics, where it provides physicians and parents with images of the fetus within the womb. Figure 4.1a shows such an ultrasound image (or sonogram) taken of a fetus. Before discussing the science behind this technology, let us first explore some of its most frequent applications.
