Flow Measurement Apparatus and Method
AssigneeDvx, LLC
InventorDavid Vilkomerson
Life of this patent
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Abstract
The velocity of fluids containing particles that scatter ultrasound can be measured by determining the Doppler shift of the ultrasound scattered by the particles in the fluid. Measuring fluid flow in cylindrical vessels such as blood vessels is an important use of Doppler ultrasound. This invention teaches using various configurations of cylindrical diffraction-grating transducers and cylindrical non-diffraction-grating transducers that suppress the Doppler shift from non-axial components of fluid velocity while being sensitive to the Doppler shift produced by axial velocity components. These configurations thus provide accurate measurement of the net flow down the vessel, even when the fluid flow is curved or not parallel to the vessel wall.
Claims20
An ultrasonic transducer apparatus for measuring a velocity of a fluid containing ultrasound scatterers flowing through a lumen, the apparatus comprising:
- a cylindrical non-diffraction-grating transducer adapted to be wrapped around the circumference of the lumen and coupled to a predetermined number of electrode elements for exciting an ultrasound beam perpendicular to the axis of said cylindrical non-diffraction-grating transducer;
- a cylindrical diffraction-grating transducer disposed in a close proximity to the cylindrical non-diffraction-grating transducer and adapted to be wrapped around the circumference of the lumen, wherein said cylindrical diffraction-grating transducer is coupled to a predetermined number of electrode elements for (1) receiving scattered signals having changing phases with respect to the ultrasound beam and (2) connecting to a circuit for determining the velocity of the fluid based on the changing phases of the received scattered signals.
A method of measuring a velocity of a fluid containing ultrasound scatterers flowing through a lumen based on a Doppler technique, the method comprising:
- disposing a cylindrical diffraction-grating transducer in a close proximity to a cylindrical non-diffraction-grating transducer;
- exciting from said cylindrical non-diffraction-grating transducer an ultrasound beam perpendicular to the axis of the cylindrical non-diffraction-grating transducer;
- receiving a scattered signal by the scatterers in the fluid at said cylindrical diffraction-grating transducer;
- and
- determining the velocity of the fluid based on the changing phases of the received scattered signal;
- whereby said cylindrical diffraction-grating transducer and said cylindrical non-diffraction-grating transducer are adapted to be wrapped around the circumference of the lumen.
An ultrasonic transducer apparatus for measuring a velocity of a fluid containing ultrasound scatterers flowing through a lumen, the apparatus comprising:
- a cylindrical diffraction-grating transducer adapted to be wrapped around the circumference of the lumen;
- a first cylindrical non-diffraction-grating transducer disposed in a close proximity to one side of the cylindrical diffraction-grating transducer and adapted to be wrapped around the circumference of the lumen and coupled to a predetermined number of electrode element for exciting at a first frequency a first ultrasound beam perpendicular to the axis of said first cylindrical non-diffraction-grating transducer;
- and
- a second cylindrical non-diffraction-grating transducer disposed in a close proximity to the opposite side of the cylindrical diffraction-grating transducer from the first cylindrical non-diffraction-grating transducer and adapted to be wrapped around the circumference of the lumen and coupled to a predetermined number of electrode element for exciting at a second frequency a second ultrasound beam perpendicular to the axis of said second cylindrical non-diffraction-grating transducer, wherein the second frequency is different from the first frequency;
- whereby said cylindrical diffraction-grating transducer is coupled to a predetermined number of electrode elements for receiving scattered signals having changing phases with respect to the first and second ultrasound beam and connecting to a circuit for determining the velocity of the fluid based on the changing phases of the received scattered signals.
An ultrasonic transducer apparatus for measuring a velocity of a scattering fluid flowing through a lumen, the apparatus comprising:
- a cylindrical non-diffraction-grating transducer adapted to be wrapped around the circumference of the lumen and coupled to a predetermined number of electrode elements for exciting an ultrasound beam perpendicular to the axis of said cylindrical non-diffraction-grating transducer;
- a first cylindrical diffraction-grating transducer and a second cylindrical diffraction-grating transducer each disposed in a close proximity to each side of the cylindrical non-diffraction-grating transducer and adapted to be wrapped around the circumference of the lumen and coupled to a predetermined number of electrode elements for (1) receiving scattered signals having changing phases with respect to said ultrasound beam and (2) connecting to a circuit for determining the velocity of the fluid based on the changing phases of the received scattered signals.
An ultrasonic transducer apparatus for measuring a velocity of a fluid containing ultrasound scatterers flowing through a lumen, the apparatus comprising:
- a cylindrical diffraction-grating transducer coupled to a predetermined number of electrode elements spacing at a distance d for exciting an ultrasound beam at a predetermined angle θ with respect to an axis of the cylindrical diffraction-grating transducer, wherein said cylindrical diffraction-grating transducer is adapted to be wrapped around the circumference of the lumen and sin θ=λ/d, wherein λ is the wavelength of said ultrasound beam;
- a cylindrical non-diffraction-grating transducer disposed in a close proximity to the cylindrical diffraction-grating transducer and adapted to be wrapped around the circumference of the lumen, wherein said cylindrical non-diffraction-grating transducer is coupled to an electrode element for receiving scattered signals having changing phases with respect to the ultrasound beam and connecting to a circuit for determining the velocity of the fluid based on the changing phases of the received scattered signals;
- whereby at least a portion of wavefronts of said ultrasound beam from opposite walls of said cylindrical diffraction-grating transducer cross at a region inside the cylindrical non-diffraction-grating transducer.
Dependencies are inferred from the claim text.