Affiliations: Precision and Intelligence Laboratory, Tokyo Institute
of Technology, Yokohama, 226-8503, Japan. E-mail: mut-work@u01.gate01.com | Cardiovascular Center, Tohoku Employee's Pension
Welfare Hospital, Sendai, 983-8512, Japan
Abstract: In order to observe and estimate the flow of fluid in
three-dimensional space, the pulsed Doppler method has been used widely.
However, the velocity information acquired is only the velocity component in
the beam direction of the wave even if an observation plane is formed by beam
scanning. Accordingly, it is difficult to know the velocity distribution in the
observation plane in tree-dimensional flow. In this paper, the new idea for
processing the velocity distribution in the beam direction on an observation
plane for transposing to flux distribution (flow function method) has been
introduced. Further, the flow in an observation domain is divided into two
kinds of flows, viz., the base flow which indicates the directivity of the flow
in the observation domain and the vortex which is considered a two-dimensional
flow. By applying the theory of a stream function to the two-dimensional flow,
and by using the physical feature of a streamline to the base flow, the
velocity component v which intersects perpendicularly to the beam direction is
estimated. The flow velocity distribution in a scanning plane (observation
plane) can be known from these two components of velocity, viz., beam direction
component u and perpendicular component to the beam direction v. The principle
was explained by an example of the blood flow measurement in normal and
abnormal heart chamber, by the ultrasonic Doppler method.
