DUAL-FREQUENCY ULTRASONIC ARRAY TRANSDUCER AND METHOD OF HARMONIC IMAGING
First Claim
1. A dual-frequency ultrasonic array transducer comprising:
- a first set of piezoelectric elements operable at their center resonant frequency to transmit ultrasonic pulses at a fundamental frequency;
a second set of piezoelectric elements operable at their center resonant frequency to receive ultrasonic pulses at a second frequency which is either twice the fundamental frequency (second harmonic) or half the fundamental frequency (primary subharmonic), wherein said first set of piezoelectric elements and said second set of piezoelectric elements are positioned in a linear alternating sequence;
an acoustic-damping backing layer;
electrical contacts bonded to the front and back of each piezoelectric element; and
an acoustic lens.
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Abstract
An ultrasonic transducer, method, and system are disclosed for performing ultrasonic harmonic imaging in a medium or a living body. The ultrasonic transducer consists of a linear array of alternating long and short elements. A first set of transducer elements is for transmitting and receiving at a fundamental frequency, and a second set of transducer elements is for receiving second harmonic or subharmonic echoes, each set operating at their respective center frequencies. This dual-frequency ultrasonic transducer is coupled to an ultrasound system wherein transmit beamforming is done at the fundamental frequency, and receive beamforming is done at the second harmonic or subharmonic frequency. When receive beamforming at the fundamental frequency is added, the method enables parallel fundamental, harmonic, compound, and difference imaging. These methods may be utilized to improve ultrasonic harmonic imaging of hard-to-image patients by optimizing the transmission of fundamental-frequency ultrasound beams and the receiving of second harmonic or subharmonic echoes, while minimizing harmonic distortion and signal losses.
74 Citations
20 Claims
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1. A dual-frequency ultrasonic array transducer comprising:
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a first set of piezoelectric elements operable at their center resonant frequency to transmit ultrasonic pulses at a fundamental frequency;
a second set of piezoelectric elements operable at their center resonant frequency to receive ultrasonic pulses at a second frequency which is either twice the fundamental frequency (second harmonic) or half the fundamental frequency (primary subharmonic), wherein said first set of piezoelectric elements and said second set of piezoelectric elements are positioned in a linear alternating sequence;
an acoustic-damping backing layer;
electrical contacts bonded to the front and back of each piezoelectric element; and
an acoustic lens. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of performing ultrasonic harmonic imaging comprising the steps of:
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(a) generating electrical pulse sequences at a fundamental frequency;
(b) applying said electrical pulse sequences to a first set of piezoelectric elements with center resonant frequency equal to said fundamental frequency, thereby converting them into acoustic pulses—
said first set of piezoelectric elements being arranged in alternating positions with respect to a second set of piezoelectric elements in a dual-frequency ultrasonic linear array transducer;
(c) introducing said acoustic pulses into an area of a medium or body to be ultrasonically imaged;
(d) receiving echoes at a second harmonic or subharmonic frequency in said second set of piezoelectric elements with center resonant frequency equal to said second harmonic or subharmonic frequency, thereby converting them into a first set of received electrical pulses;
(e) beamforming said first set of received electrical pulses so as to focus on second harmonic or subharmonic echoes originating from a specified depth zone within said medium or said body;
(f) assembling a second harmonic or subharmonic image by scan converting all image vectors comprised of intensities mapped from said first set of received electrical pulses; and
(g) displaying said second harmonic or subharmonic image. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An apparatus comprising:
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a first plurality of ultrasonic transducer element means for transmitting acoustic energy at a first set of frequencies into an area of a subject being scanned;
a second plurality of ultrasonic transducer element means for receiving acoustic energy at a second set of frequencies from an area of a subject being scanned, wherein said first plurality of ultrasonic transducer element means is laid out in an alternating sequence with respect to said second plurality of ultrasonic transducer element means;
an acoustic-damping backing layer means;
electrical connection means; and
an acoustic lens means. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification