US 6,048,315 AGranted

Method and apparatus for ultrasonic synthetic transmit aperture imaging using orthogonal complementary codes

AssigneeGeneral Electric Company

InventorsRichard Yung Chiao, Lewis Jones Thomas, III

Life of this patent

Estimating the term…

Loading patent…

Abstract

Signal-to-noise ratio in synthetic transmit aperture imaging is significantly increased by encoding the transmit signals in orthogonal complementary codes for multiple point sources to be transmitted simultaneously. A number N of elements of a transducer array are simultaneously activated to transmit unfocused ultrasound waves during each one of N transmit events. For each transmit event, a different set of N code sequences is applied by a controller to N pulsers for the transducers to drive the transducers. The imaging depth is divided into several zones and code lengths are employed which increase with depth. A Hadamard construct of the orthogonal complementary sets, which requires only 2N correlations for decoding, is used.

Claims17

Dependent claims

A system for imaging ultrasound scatterers, comprising:

an ultrasound transducer array including a multiplicity of transducer elements for transmitting ultrasound waves and detecting ultrasound echoes reflected by said ultrasound scatterers;
transmit means coupled to said transducer array for pulsing a first number N of transducer elements, for N transmit events, with signals derived from N orthogonal complementary code sets, each of said code sets comprising N complementary code sequences;
receive means coupled to said transducer array for receiving signals from a second number M of transducer elements of said multiplicity following each of said N transmit events, each set of signals received at said M transducer elements representing a respective received data sequence;
analog-to-digital conversion means for converting each of the N.times.M received signals into a respective digital signal;
means for decoding the N.times.M digital signals by computing the sum of the N received data sequences cross-correlated with the N orthogonal complementary code sequences transmitted from each respective one of said N transducer elements to form a decoded data set for said each respective one of said N transducer elements;
beamforming means for forming a beamformed data set from the decoded data sets;
and
means (24) for displaying an image that is a function of said beamformed data set.

5 more elements

A method for imaging ultrasound scatterers in a field of view, comprising the steps of:

driving a first set of transducer elements of a multiplicity of transducer elements in a transducer array, during each one of a first plurality of transmit events, with pulses derived from a first set of orthogonal complementary code sequences having a first length, each transmit event of said first plurality comprising driving said first set of transducer elements with a respective one of said first set of orthogonal complementary code sequences;
receiving signals from a second set of transducer elements following each of said transmit events of said first plurality to form a first received data set of received data sequences corresponding to ultrasound scatterers located at a first range of depth relative to the transducer array;
converting each of said received data sequences of said first received data set into a respective digital signal to form a first set of digital signals;
decoding said first set of digital signals by computing the sum of the received data sequences of said first received data set cross-correlated with the respective orthogonal complementary code sequences of said first set of orthogonal complementary code sequences to form a first decoded data set for each one of said first set of transducer elements;
forming a first beamformed data set from the first decoded data sets;
and
displaying a first image which is a function of said first beamformed data sets.

4 more elements

Dependencies are inferred from the claim text.