When an ultrasonic beam is radiated into the bloodvessel by a transducer placed on the surface of the skin, the reflected waves are produced from the blood-flow. Hence they can be detected as a kind of tone by means of a sensitive receiver. Because the intensity and the frequency character of this tone is proportional to the velocity of the blood-flow, it is possible to investigate the behavior of the blood-flow through this method. Tones are consisted of two kinds, one of them being produced by the carotid arterial system while the other produced by the limbs arterial system. The author suggests to make a diagnosis of Arterial sclerosis utilizing this method.
