Patent ID: 8852110

Claim:
A method of measuring a velocity of a fluid containing ultrasound scatterers flowing through a lumen based on a Doppler technique, the method comprising: coupling a cylindrical diffraction-grating transducer and a cylindrical non-diffraction-grating transducer such that they are adjacent to each other; exciting from said cylindrical diffraction-grating transducer an ultrasound beam at a predetermined angle with respect to the axis of the cylindrical diffraction-grating transducer; receiving a scattered signal by the scatterers in the fluid at said cylindrical non-diffraction-grating transducer; and determining the velocity of the fluid based on 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 and configured for wavefronts of said ultrasound beam from opposite walls of said cylindrical non-diffraction-grating transducer to form multiple equiphase planes perpendicular to the axis of the cylindrical diffraction-grating transducer, and said determining the velocity is based on the changing phases of the received scattered signal corresponding to the scatterers in the fluid crossing at least one of said equiphase planes.