Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-02-23
2002-06-25
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S459000
Reexamination Certificate
active
06409667
ABSTRACT:
BACKGROUND
This invention relates to a medical diagnostic ultrasound transducer system and method for harmonic imaging. In particular, a transducer system providing increased bandwidth for imaging with harmonic echoes from tissue, fluid or added contrast agents is provided.
Acoustic energy is transmitted into a patient at fundamental transmit frequencies. Acoustic energy is reflected off of tissue, fluid or other structures within the patient. The reflections include energy at the fundamental frequency band as well as energy generated at harmonic frequencies of the fundamental frequency band. The transducer converts the acoustic energy into an electrical signal.
Transducer bandwidth may limit the actual response, reducing the information content at harmonic or other frequencies. Manufacturing transducers with a 6 dB bandwidth or better exceeding 80% of the desired frequency range is difficult and expensive. For harmonic imaging, a 6 dB bandwidth exceeding 100 or 140% is preferably provided. For example, the transducer may transmit energy in a 3 to 5 MHz frequency range and receive information of interest in the 6 to 9 MHz range.
Larger bandwidth transducers are generally desirable for any type of ultrasonic diagnostic imaging. For example, transducers with a wide bandwidth are used for obtaining information at different fundamental frequencies during a same or different imaging sessions. Various techniques have been suggested for providing wide bandwidth transducers. For example, T. R. Gururaja et al in ‘Medical Ultrasonics Transducers With Switchable Frequency Bands Centered about f
0
and 2f
0
’, 1997 IEEE Ultrasonic Symposium, pp. 1659-1662, disclose an electrostrictive transducer element using two layers. A selected bias is applied to one layer, and a transmit waveform is applied to an electrode between the two layers for wide bandwidth transmission. As another example, J. Hossack et al. in Improving the Characteristics of A Transducer Using Multiple Piezoelectric Layers, IEEE Transactions On Ultrasonics, Ferroelectrics and Frequency Control, Vol. 40, No. 2, March 1993, disclose a two-layer piezoelectric single element transducer. A different waveform is applied to each of the layers on transmit, and phasing or delays are applied to signals from one of the layers relative to another layer on receive. As another example, different materials in a single layer transducer element may be used to extend the frequency range of the transducer.
U.S. Pat. No. 5,957,851, the disclosure of which is incorporated herein by reference, discloses an ultrasound transducer with multiple piezoelectric layers for use in harmonic imaging. Diodes or a transistor is used to isolate one layer from the other during transmit or receive. The same transducer is used to transmit at a fundamental frequency and receive at a harmonic frequency. For this passive switching system, the same transmit and receive processing is performed for each layer when each layer is being used.
BRIEF SUMMARY
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiments described below include a method and transducer system for harmonic imaging. At least one transducer element is provided. The transducer element comprises two stacked piezoelectric layers. The layers are stacked in the height or thickness direction which is perpendicular to an elevation-azimuth plane (i.e. azimuth is X direction, elevation is Y direction and range is Z direction). Information from each of the layers is independently processed during one of a transmit event, a receive event, and both of transmit and receive events. Information from the transducer element is provided to a filter. The filter isolates harmonic information for imaging. By providing a multi-layer transducer element with independent processing for each layer, a wide bandwidth transducer for harmonic imaging is provided. The null associated with most transducers at the second harmonic of a fundamental frequency is removed or lessened.
Further aspects and advantages of the invention are described below in conjunction with the preferred embodiments.
REFERENCES:
patent: 4096756 (1978-06-01), Alphonse
patent: 4240003 (1980-12-01), Larson, III
patent: 4276491 (1981-06-01), Daniel
patent: 4354132 (1982-10-01), Borburgh et al.
patent: 4356422 (1982-10-01), van Maanen
patent: 4427912 (1984-01-01), Bui et al.
patent: 5115809 (1992-05-01), Saitoh et al.
patent: 5311095 (1994-05-01), Smith et al.
patent: 5410205 (1995-04-01), Gururaja
patent: 5415175 (1995-05-01), Hanafy et al.
patent: 5438998 (1995-08-01), Hanafy
patent: 5446333 (1995-08-01), Ishida et al.
patent: 5630420 (1997-05-01), Vaitekunas
patent: 5675554 (1997-10-01), Cole et al.
patent: 5685308 (1997-11-01), Wright et al.
patent: 5690608 (1997-11-01), Watanabe et al.
patent: 5724976 (1998-03-01), Mine et al.
patent: 5740128 (1998-04-01), Hossack et al.
patent: 5825117 (1998-10-01), Ossmann et al.
patent: 5920972 (1999-07-01), Palczewska et al.
patent: 5957851 (1999-09-01), Hossack
patent: 5984869 (1999-11-01), Chiao et al.
patent: 6005827 (1999-12-01), Hossack et al.
Bouakaz et al., 2000, “Improved harmonic imaging with a new pahsed array transducer”, ultrasound in Medicine and Biology, v 26 n SUPPL. 2 2000., p. A58.*
John A. Hossack et al.,Multiple Layer Transducers for Broadband Applications; 1991 Ultrasonics Symposium; pp. 605-610.
John A. Hossack et al., Improving the Characteristics of a Transducer Using Multiple Piezoelectric Layers; IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, vol. 40, No. 2; pp. 131-139.
John A. Hossack et al., Improving Transducer Performance Using Multiple Active Layers; SPIE vol. 1733 (1992); pp. 284-296.
T. R. Gururaja et al., Medical Ultrasound Transducers with Switchable Frequency Bands Centered About f0and 2f0; 1997 IEEE Ultrasonics Symposium; pp. 1659-1662.
Jie Chen et al., DC-Biased Electrostrictive Materials and Transducers for Medical Imaging; 1997 IEEE Ultrasonics Symposium; pp. 1651-1658.
L. B. Russell et al., Thickness-Mode Modeling of Active Multi-Layered Piezoelectric Transducers and the Application to “SMART” Sensor Design; 1994 IEEE Ultrasonics Symposium; pp. 615-618.
Acuson Corporation
Brinks Hoffer Gilson & Lione
Imam Ali M.
Lateef Marvin M.
Summerfield Craig A.
LandOfFree
Medical diagnostic ultrasound transducer system and method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Medical diagnostic ultrasound transducer system and method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Medical diagnostic ultrasound transducer system and method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2897816