This invention relates to acoustical Doppler velocity estimations and, more specifically, relates to the calculation of body fluid velocity, such as blood velocity and the like, based on the Doppler shift of ultrasonic signals.
Color flow and Doppler imaging in current ultrasound systems are both affected by the same limitation. If a Doppler style processing, such as a Fourier transform for Doppler or an autocorrelation for color flow (or exclusively down-range processing, such as a time domain cross correlation algorithm) are used to measure either blood flow or tissue motion, only the velocity component along the line of the ultrasound beam direction is measured, and any orthogonal component is not usually calculated. Various schemes have been proposed and even implemented to compensate for this problem. In Doppler, the user is typically given the opportunity to position a cursor indicating the direction of blood flow, so that the true velocity vector then can be adjusted by the cosine of the Doppler angle. In color flow, various schemes, including triangulation and lateral cross correlation, have been studied and published in the literature. However, none of the known systems effectively calculates the true velocity of blood flow in a manner which eliminates operator errors. This invention solves that problem.