<title>Doppler analysis of blood flow using a phased array beam steering</title>

Abstract

This paper presents an analysis of the Doppler shift and spread caused by moving blood flows using only a phased array beam steering. A mathematical system model provides the exact phase information without using approximation, which a conventional beam steering and focusing is based on. The target's movement relates to the beam steering time known, as slow time. We assume that the target is stationary when the beam at a certain steering angle interacts with the target under the beam propagation time known, as fast time. The velocity component in the beam direction relates to Doppler shift. The other velocity component perpendicular to the beam propagation direction corresponds to Doppler spread. The true velocity vector of the region of interest (ROI) can be estimated with a single phased array that is based on measurement of the Doppler shift and spread in the spatial domain. In our analysis, we suppose that the ROI contains multiple velocity vectors where each vector has a different magnitude and direction. In fact, the maximum and mean velocity of the ROI can be acquired under laminar flows. If the ROI is with turbulent flows it hardly estimates ROI's mean velocity. However, it is possible to indicate whether it is a laminar or turbulent flow. The numerical simulation results will be shown.