While a number of new imaging techniques have been introduced during the last few years, diagnostic ultrasound has proved to be one of the most clinically useful. The technique involves the use of high frequency, relatively low intensity sound waves for imaging of deep organs of the body.
Two formats of information are obtained by ultrasound. Static image scanners create a single, large field-of-view image of a portion of the anatomy, whereas real-time scanners produce a live-action or fluoroscopiclike image. The latter technique has the advantage of ease of operation and visualization of dynamic activity and the disadvantage of a smaller field of view than conventional "B-scan" or staticimage scans.
Both techniques use similar instrumentation, beginning with a transducer that "rings" with a characteristic frequency when a voltage is applied. For conventional diagnostic purposes, frequencies in the range of 2.5 to 7.5 million cps (megahertz) are used. The audible range
Neiman HL, Vogelzang RL. Diagnostic UltrasoundA Review of the State of the Art. Arch Dermatol. 1984;120(2):248-253. doi:10.1001/archderm.1984.01650380108024