An Analytical Procedure of Calibration for the Pulsed Ultrasonic Doppler Flow Meter

Abstract

The use of Doppler ultrasonics provides one of the few, if not the only, methods of noninvasive measurement of blood flow and velocity in the body. In terms of overall accuracy the pulsed ultrasonic Doppler flow meter, operating in a radar-like range-gated manner, currently offers the best solution. However, under certain circumstances this device suffers from an inherent lack of spatial resolution, resulting in the distortion of the measured velocity profiles. The device is modeled as a convolution integral, incorporating the physical characteristics of the flow meter, and those of the velocity field, as established in previous work. The distortion of the measured velocity profile is corrected by solving the integral equation, or “deconvolving” using the discrete Fourier transforms implemented on a digital computer. The methods discussed for obtaining the “true” velocity profile require only a knowledge of the flow meter characteristics and its output. No assumptions as to the nature of the true profile are necessary.