application of the Doppler effect in ultrasound to detect movement of scatterers (usually red blood cells) by the analysis of the change in frequency of the returning echoes.In many settings, ultrasound has supplanted x-radiography as the imaging method of choice, because it poses no known risk to patients, is noninvasive, and is of moderate cost. Doppler-created ultrasound makes possible real-time viewing of tissues, blood flow, and organs that cannot be observed by any other method. It is particularly valuable in cardiology and obstetrics.
