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US 6,443,897 B1Granted
Refraction delay error correction using agile beamformer
AssigneeGE Medical Systems Global Technology Company, LLC
InventorsDavid T. Dubberstein, Steven C. Miller
Life of this patent
Estimating the term…
Abstract
A method and an apparatus for correcting refraction delay errors on curved probes for all ranges using cordic rotation. The angle φ from the normal of an element to the focus is determined as a function of the angle of cordic rotation. Then a delay error correction is indexed using this angle φ. The angular correction method is efficient in that it uses the inherent property of cordic rotation to calculate the only range-dependent variable required for the correction. Thus the additional hardware required to calculate the corrections is minimal, as the remaining correction variables are vector and range independent.
Claims31
A beamforming system comprising:
- a transducer array comprising a multiplicity of transducer elements;
- a multiplicity of receive channels respectively operatively coupled to said multiplicity of transducer elements;
- a cordic rotator connected to calculate respective hypotenuses for each transducer element to a focal position, said calculation being performed for each of a multiplicity of focal positions, each hypotenuse being a function of focal position data representing a respective focal position and transducer element position data representing the position of a respective transducer element;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said cordic rotator;
- and
- a time delay generator for applying respective time delays to respective receive channels, each time delay being a function of a respective hypotenuse calculation result output by said cordic rotator and a respective delay adjustment output by said angular refraction correction circuit.
3 more elements
A beamforming system comprising:
- a transducer array comprising a multiplicity of transducer elements arranged in a plane having x and z coordinate axes;
- and
- a beamformer comprising:
- a multiplicity of receive channels respectively operatively coupled to said multiplicity of transducer elements;
- first memory storing x and z coordinates of a focal position;
- second memory storing respective sets of coordinates of respective positions of said multiplicity of transducer elements, each coordinate set comprising an x coordinate and a z coordinate;
- a first adding/subtracting circuit connected to said first and second memories for forming respective x coordinate differences between said x coordinate of said focal position and respective x coordinates of said element positions;
- a second adding/subtracting circuit connected to said first and second memories for forming respective z coordinate differences between said z coordinate of said focal position and respective z coordinates of said element positions;
- a cordic rotator connected to said first and second adding/subtracting circuits for performing coordinate transformations of the outputs of said first and second adding/subtracting circuits;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said cordic rotator;
- and
- a time delay generator for applying respective time delays to respective receive channels, each time delay being a function of a respective hypotenuse calculation result output by said cordic rotator and a respective delay adjustment out by said angular refraction correction circuit.
9 more elements
A beamforming system comprising:
- a transducer array comprising a multiplicity of transducer elements;
- a multiplicity of receive channels respectively operatively coupled to said multiplicity of transducer elements;
- first and second cordic rotators connected in series to calculate respective hypotenuses for each transducer element to a focal position, said calculation being performed for each of a multiplicity of focal positions, each hypotenuse being a function of focal position data representing a respective focal position and transducer element position data representing the position of a respective transducer element;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said first and second cordic rotators;
- and
- a time delay generator for applying respective time delays to respective receive channels, each time delay being a function of a respective hypotenuse calculation result output by said second cordic rotator and a respective delay adjustment output by said angular refraction correction circuit.
3 more elements
A beamforming system comprising:
- a transducer array comprising a multiplicity of transducer elements;
- a multiplicity of pulsing circuits respectively operatively coupled to said multiplicity of transducer elements;
- a cordic rotator connected to calculate respective hypotenuses for each transducer element to a focal position, said calculation being performed for each of a multiplicity of focal positions, each hypotenuse being a function of focal position data representing a respective focal position and transducer element position data representing the position of a respective transducer element;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said cordic rotator;
- and
- a time delay generator for applying respective time delays to respective pulsing circuits, each time delay being a function of a respective hypotenuse calculation result output by said cordic rotator and a respective delay adjustment output by said angular refraction correction circuit.
3 more elements
A beamforming system comprising:
- a transducer array comprising a multiplicity of transducer elements arranged in a plane having x and z coordinate axes;
- and
- a beamformer comprising:
- a multiplicity of pulsing circuits respectively operatively coupled to said multiplicity of transducer elements;
- first memory storing x and z coordinates of a focal position;
- second memory storing respective sets of coordinates of respective positions of said multiplicity of transducer elements, each coordinate set comprising an x coordinate and a z coordinate;
- a first adding/subtracting circuit connected to said first and second memories for forming respective x coordinate differences between said x coordinate of said focal position and respective x coordinates of said element positions;
- a second adding/subtracting circuit connected to said first and second memories for forming respective z coordinate differences between said z coordinate of said focal position and respective z coordinates of said element positions;
- a cordic rotator connected to said first and second adding/subtracting circuits for performing coordinate transformations of the outputs of said first and second adding/subtracting circuits;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said cordic rotator;
- and
- a time delay generator for applying respective time delays to respective pulsing circuits, each time delay being a function of a respective hypotenuse calculation result output by said cordic rotator and a respective delay adjustment out by said angular refraction correction circuit.
9 more elements
A beamforming system comprising:
- a transducer array comprising a multiplicity of transducer elements;
- a multiplicity of pulsing circuits respectively operatively coupled to said multiplicity of transducer elements;
- first and second cordic rotators connected in series to calculate respective hypotenuses for each transducer element to a focal position, said calculation being performed for each of a multiplicity of focal positions, each hypotenuse being a function of focal position data representing a respective focal position and transducer element position data representing the position of a respective transducer element;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said first and second cordic rotators;
- and
- a time delay generator for applying respective time delays to respective pulsing circuits, each time delay being a function of a respective hypotenuse calculation result output by said second cordic rotator and a respective delay adjustment output by said angular refraction correction circuit.
3 more elements
An imaging system comprising:
- a transducer array comprising a multiplicity of transducer elements arranged in a plane;
- a delay calculator for calculating a set of respective receive time delays as a function of a focal position and respective positions of a set of said transducer elements;
- a transmit beamformer programmed to activate said transducer array to transmit a focused ultrasound beam;
- a receive beamformer comprising a set of receive channels for converting respective analog signals from said set of transducer elements into respective vectors of digital samples, a channel control bus for applying said set of respective receive time delays to said respective vectors of digital samples in said set of receive channels, and a beamsummer for summing at least said time-delayed vectors of digital samples from said set of receive channels to produce a net receive signal;
- a processor for deriving an image signal from said net receive signal;
- and
- a display device for displaying an image having an image portion which is a function of said image signal,
- wherein said delay calculator comprises:
- a cordic rotator connected to calculate respective hypotenuses for each transducer element of said set to a focal position, said calculation being performed for each of a multiplicity of focal positions, each hypotenuse being a function of focal position data representing a respective focal position and transducer element position data representing the position of a respective transducer element;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said cordic rotator;
- and
- a time delay generator for applying respective time delays to respective receive channels of said set, each time delay being a function of a respective hypotenuse calculation result output by said cordic rotator and a respective delay adjustment output by said angular refraction correction circuit.
9 more elements
An imaging system comprising:
- a transducer array comprising a multiplicity of transducer elements arranged in a plane;
- a delay calculator for calculating a set of respective receive time delays as a function of a focal position and respective positions of a set of said transducer elements;
- a transmit beamformer programmed to activate said transducer array to transmit a focused ultrasound beam;
- a receive beamformer comprising a set of receive channels for converting respective analog signals from said set of transducer elements into respective vectors of digital samples, a channel control bus for applying said set of respective receive time delays to said respective vectors of digital samples in said set of receive channels, and a beamsummer for summing at least said time-delayed vectors of digital samples from said set of receive channels to produce a net receive signal;
- a processor for deriving an image signal from said net receive signal;
- and
- a display device for displaying an image having an image portion which is a function of said image signal,
- wherein said delay calculator comprises:
- first and second cordic rotators connected in series to calculate respective hypotenuses for each transducer element of said set to a focal position, said calculation being performed for each of a multiplicity of focal positions, each hypotenuse being a function of focal position data representing a respective focal position and transducer element position data representing the position of a respective transducer element;
- an angular refraction correction circuit for outputting a delay adjustment which is a function of rotation angle data from said first and second cordic rotators;
- and
- a time delay generator for applying respective time delays to respective receive channels of said set, each time delay being a function of a respective hypotenuse calculation result output by said second cordic rotator and a respective delay adjustment output by said angular refraction correction circuit.
9 more elements
A method for correcting for time delay errors due to refraction during ultrasound beamforming, comprising the steps of:
- storing geometry parameters of a transducer array having a multiplicity of transducer elements;
- storing vector parameters for forming a focused beam having a focal position;
- calculating respective hypotenuses representing the distances from said focal position to said respective transducer elements as a function of said geometry parameters and said vector parameters using multiple stages of cordic rotation to derive each hypotenuse;
- determining a delay adjustment which is a function of said geometry parameters and rotation angle data used in said multiple stages of cordic rotation;
- generating respective time delays as a function of said respective calculated hypotenuses and said respective delay adjustments;
- and
- forming a beam using said respective time delays.
4 more elements
A method for correcting time delays errors due to refraction during ultrasonic beamforming, comprising the steps of:
- calculating a hypotenuse representing the distance from a focal position to a transducer element using cordic rotation;
- calculating an angle φ from the normal of the transducer element to the focal position as a function of an angle of said cordic rotation;
- generating a delay error correction as a function of said angle φ;
- and
- generating a time delay as a function of said calculated hypotenuse and said delay error correction.
2 more elements
Dependencies are inferred from the claim text.