Ultrasonic harmonic imaging system and method

In a method for imaging a target, said method comprising the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency, the improvement wherein step (a) comprises the steps of:

• (a1) generating a transmit waveform;
• and
• (a2) filtering the transmit waveform with a filter adapted to reduce ultrasonic energy in the transmit waveform at the harmonic of the fundamental frequency to at least -30 dB with respect to the fundamental frequency.

The method for imaging a target, said method comprising the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency, the improvement wherein step (a) comprises the step of:

• (a1) generating a transmit waveform with a programmable waveform generator such that ultrasonic power in the transmit waveform at the harmonic of the fundamental frequency is reduced by at least -30 dB with respect to ultrasonic power in the transmit waveform at the fundamental frequency.

In a method for imaging a target, said method comprising the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency, the improvement wherein step (a) comprises the step of:

• (a1) focusing ultrasonic energy in a transmit beam having a line focus.

In a method for imaging a target, said method comprising the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency, the improvement wherein step (a) comprises the step of:

• (a1) focusing ultrasonic energy in a transmit beam having an elongated high power region by focusing at least first selected frequency components from at least a first plurality of transducer elements at a first range and focusing at least second frequency components from at least a second plurality of transducer elements at a second range.

In a method for imaging a target, said method comprising the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency, the improvement wherein step (a) comprises the step of:

• (a1) transmitting ultrasonic energy in power bursts, each power burst characterized by a respective frequency spectrum having a respective center frequency, a respective peak amplitude, and a respective bandwidth, the bandwidth of each power burst being at least about 30% of the respective center frequency at points -6.8 dB with respect to the respective peak amplitude, said frequency spectra reduced at the harmonic by more than -30 dB with respect to the peak amplitude.

In a method for imaging a target, said method comprising the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency, the improvement wherein step (a) comprises the step of:

• (a1) transmitting ultrasonic energy in power bursts, each power burst characterized by a respective frequency spectrum having a respective peak amplitude near the fundamental frequency, said frequency spectrum reduced within a first bandwidth greater than or equal to .+-.X% of the harmonic of the fundamental frequency by more than -YdB with respect to the peak amplitude, where X is equal to 5 and Y is equal to 30.

In an ultrasonic imaging system comprising a transmit beamformer operative to transmit energy at a fundamental frequency, and a receive beamformer responsive to ultrasonic energy at a harmonic of the fundamental frequency, the improvement comprising:

• means, included in the transmit beamformer, for transmitting ultrasonic energy in power bursts, each power burst comprising a respective envelope shape, each envelope shape rising gradually to a respective maximum value and falling gradually from the respective maximum value.

In an ultrasonic imaging system comprising a transmit beamformer operative to transmit energy at a fundamental frequency, and a receive beamformer responsive to ultrasonic energy at a harmonic of the fundamental frequency, the improvement comprising:

• means, included in the transmit beamformer, for generating a transmit waveform;
• and
• a filter, responsive to the transmit waveform, to reduce ultrasonic energy in the transmit waveform at the harmonic of the fundamental frequency by at least -30 dB with respect to the fundamental frequency.

In an ultrasonic imaging system comprising a transmit beamformer operative to transmit energy at a fundamental frequency, and a receive beamformer responsive to ultrasonic energy at a harmonic of the fundamental frequency, the improvement comprising:

• a programmable waveform generator, included in the transmit beamformer, operative to generate a transmit waveform in which ultrasonic power in the transmit waveform at the harmonic of the fundamental frequency is reduced by at least -30 dB with respect to ultrasonic power in the transmit waveform at the fundamental frequency.

In an ultrasonic imaging system comprising a transmit beamformer operative to transmit energy at a fundamental frequency, and a receive beamformer responsive to ultrasonic energy at a harmonic of the fundamental frequency, the improvement comprising:

• means, included in the transmit beamformer, for focusing ultrasonic energy in a transmit beam having a line focus.

In an ultrasonic imaging system comprising a transmit beamformer operative to transmit energy at a fundamental frequency, and a receive beamformer responsive to ultrasonic energy at a harmonic of the fundamental frequency, the improvement comprising:

• means, included in the transmit beamformer, for focusing ultrasonic energy in a transmit beam having an elongated high power region by focusing at least first selected frequency components from at least a first plurality of transducer elements at a first range and focusing at least second frequency components from at least a second plurality of transducer elements at a second range.

In an ultrasonic imaging system comprising a transmit beamformer operative to transmit energy at a fundamental frequency, and a receive beamformer responsive to ultrasonic energy at a harmonic of the fundamental frequency, the improvement comprising:

• means, included in the transmit beamformer, for transmitting ultrasonic energy in power bursts, each power burst characterized by a respective frequency spectrum having a respective center frequency, a respective peak amplitude, and a respective bandwidth, the bandwidth of each power burst being at least about 30% of the respective center frequency at points -6.8 dB with respect to the respective peak amplitude, said frequency spectra reduced at the harmonic by more than -30 dB with respect to the peak amplitude.

In an ultrasonic imaging system comprising a transmit beamformer operative to transmit energy at a fundamental frequency, and a receive beamformer responsive to ultrasonic energy at a harmonic of the fundamental frequency, the improvement comprising:

• means, included in the transmit beamformer, for transmitting ultrasonic energy in power bursts, each power burst characterized by a respective frequency spectrum having a respective peak amplitude near the fundamental frequency, said frequency spectrum reduced within a first bandwidth greater than or equal to .+-.X% of the harmonic of the fundamental frequency by more than -YdB with respect to the peak amplitude, where X is equal to 5 and Y is equal to 30.