Method and apparatus for adjustable frequency scanning in ultrasound imaging

A method for scanning a field of view with a plurality of ultrasonic transmit beams, at least a first and a second of which traverse different paths through said field of view, comprising the steps of:

• providing at least one baseband waveform for different ones of said transmit beams;
• modulating each of said baseband waveforms for each given one of said transmit beams to an ultrasonic frequency for said given transmit beam, the ultrasonic frequency for said first transmit beam being higher than the ultrasonic frequency for said second transmit beam;
• for each given one of said transmit beams, exciting each respective transducer in an array of ultrasonic transducers with a respective excitation signal which is responsive to a respective one of said modulated baseband waveforms for the given transmit beam;
• forming a plurality of ultrasonic receive beams, each of said receive beams being represented with a plurality of input waveforms received from corresponding transducers in said array of transducers and containing ensonified object responses for a plurality of ranges along the receive beam, at least a first and a second one of said receive beams traversing different paths through said field of view;
• and
• demodulating the input waveforms with a respective demodulation frequency to form demodulated baseband waveforms for each of said receive beams the demodulation frequency for said first receive beam at a given range being higher than the demodulation frequency for said second receive beam at said given range.

Apparatus for scanning a field of view with a plurality of ultrasonic transmit beams, including a first and a second of said beams, comprising:

• an array of ultrasonic transducers having a surface;
• modulation circuitry for modulating of at least one baseband waveform for each of said transmit beams to an ultrasonic frequency for said each transmit beam, the ultrasonic frequency for said first transmit beam being higher than the ultrasonic frequency for said second transmit beam;
• and
• excitation circuitry which, for each of said transmit beams, excites each transducer in an array of ultrasonic transducers with an excitation signal which is responsive to said modulated baseband waveforms for the transmit beams, said first and second transmit beams being produced from said array with different paths through said field of view.

Apparatus for scanning a field of view with a plurality of ultrasonic receive beams including a first and a second of said receive beams, each of said receive beams being represented with a plurality of input waveforms received from corresponding transducers in an array of transducers and containing information at a plurality of ranges, comprising:

• an array of transducers having a surface;
• beamformation apparatus forming said receive beams, at least said first and second receive beams traversing different paths through said field of view;
• and
• demodulation circuitry for demodulating the input waveforms to demodulated baseband waveforms for each of said receive beams with a respective demodulation frequency for each receive beam, a demodulation frequency for said first receive beam at a given range being higher than a demodulation frequency for said second receive beam at said given range.

Apparatus for scanning a field of view with a plurality of ultrasonic transmit beams including a first and a second of said transmit beams, and a plurality of ultrasonic receive beams including a first and a second of said receive beams, each of said receive beams being represented with a plurality of input waveforms received from corresponding transducers in an array of transducers containing ensonified object responses at a plurality of ranges, comprising:

• an array of ultrasonic transducers having a surface;
• modulation circuitry for modulating of at least one baseband waveform for each of said transmit beams to an ultrasonic frequency for said transmit beam, the ultrasonic frequency for said first transmit beam being higher than the ultrasonic frequency for said second transmit beam;
• and
• excitation circuitry which, for each one of said transmit beams, excites each transducer in said array of ultrasonic transducers with a respective excitation signal which is responsive to one of said modulated baseband waveforms for the transmit beam, said first and second transmit beams being produced from said array with different paths through said field of view;
• beamformation apparatus forming said receive beams, at least said first and second receive beams traversing different paths through said field of view;
• and
• demodulation circuitry for demodulating the input waveforms for each of said receive beams with a respective demodulation frequency for each receive beam, a demodulation frequency for said first receive beam at a given range being higher than a demodulation frequency for said second receive beam at said given range.

Apparatus for scanning a field of view with a plurality of ultrasonic transmit beams including a first and a second one of said transmit beams, comprising:

• an array of ultrasonic transducers having a surface;
• means for exciting multiple elements of said array of transducers with appropriate time delays to produce said first transmit beam with a first ultrasonic frequency, said first transmit beam extending at a first angle relative to a normal to said surface of said array and having a first point of intersection with said surface of said array;
• means for exciting said array of transducers to produce said second transmit beam with a second ultrasonic frequency, said second transmit beam extending at said first angle relative to a normal to said surface of said array and having a second point of intersection with said surface of said array,
• wherein said second point of intersection is different from said first point of intersection, and wherein said second ultrasonic frequency is below said first ultrasonic frequency.

A method for scanning a field of view with a plurality of ultrasonic transmit beams, at least a first and a second of which traverse different paths through said field of view, comprising the steps of:

• generating a set of waveform samples for each of said transmit beams at an ultrasonic frequency, the ultrasonic frequency for said first transmit beam being higher than the ultrasonic frequency for said second transmit beam;
• for each of said transmit beams, exciting each respective transducer in an array of ultrasonic transducers with a respective excitation signal which is responsive to a respective one set of said generated waveform samples to produce the transmit beam;
• forming a plurality of ultrasonic receive beams, each of said receive beams being represented with a plurality of input waveforms received from corresponding transducers in said array of transducers and containing information for a plurality of ranges along the receive beam, at least a first and a second one of said receive beams traversing different paths through said field of view;
• and
• demodulating the input waveforms to form demodulated baseband waveforms for each of said receive beams with a respective demodulation frequency, a demodulation frequency for said first receive beam at a given range being higher than a demodulation frequency-for said second receive beam at said given range.

Apparatus for scanning a field of view with a plurality of ultrasonic transmit and receive beams, including with a first and a second transmit beam, and first one or more receive beams corresponding to said first transmit beam and second one or more receive beams corresponding to said second transmit beam comprising:

• an array of ultrasonic transducers;
• and
• circuitry for modulating waveforms to create transmit excitation waveforms associated with transmit beams, and for demodulating waveforms associated with receive beams, said circuitry including means for producing excitation waveforms at a higher ultrasonic frequency associated with said first transmit beam and a lower ultrasonic frequency associated with a second transmit beam;
• wherein said first and second transmit beams are produced from said array along different paths through said field of view.