JP2004181094A - Ultrasonograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic wave observation device carrying out diagnosis by exciting composite piezoelectric elements that can enhance the multi-purpose use of ultrasonograph observation devices by using broad bands and improving ultrasonic wave images at high frequency side, and can also be applied to harmonic images by setting the high frequency band multiple times the low frequency band. <P>SOLUTION: A first switch 11, a first pulse driver 13, a first resonance inductor 15, a first positive pole 21 of an ultrasonic wave oscillator 20, and a first STC circuit 31 constitute a first system A1 corresponding to low frequencies. A second switch 12, a second pulse driver 14, a second resonance inductor 16, a second positive pole 22 of the ultrasonic wave oscillator 20, and a second STC circuit 32 constitute a second system A2 corresponding to high frequencies. The ultrasonograph 1 selects modes for broad bands or modes for improving ultrasonic wave images at high-frequency sides by operating the first and second switches 11 and 12. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus that generates a cross-sectional image by transmitting and receiving ultrasonic waves to and from a subject using a composite piezoelectric vibrator.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an ultrasonic diagnostic apparatus is connected to an ultrasonic endoscope and an ultrasonic probe to create a cross-sectional image of a body cavity, and is used for depth-of-path diagnosis of a lesion, substantial diagnosis of an organ, and the like.
[0003]
An ultrasonic transducer is built in the distal end of the ultrasonic endoscope and the ultrasonic probe. The electric drive pulse transmitted from the ultrasonic diagnostic apparatus is converted into an acoustic ultrasonic pulse by the ultrasonic vibrator, and is applied to the body tissue. Since the reflected wave returns from the body, the ultrasonic transducer converts it into an electrical signal. The ultrasonic diagnostic apparatus is configured to perform signal processing or the like on an electrical signal from an ultrasonic transducer and display the same as an ultrasonic tomographic image.
[0004]
Recently, a wideband vibrator using a CPM (composite piezoelectric element) as the ultrasonic vibrator has appeared (for example, see Patent Document 1).
[0005]
Because the band of the vibrator has been greatly expanded, the elements of the conventional PZT vibrator {two-component piezoelectric ceramics Pb (Ti, Zr) O ₃ } are divided for each frequency, and a plurality of ultrasonic endoscopes exist. Can be realized by one. On the other hand, since one element can cope with multiple frequencies, a problem has arisen when using a high frequency that emphasizes image quality.
[0006]
That is, in the PZT, the Q value is very high, and the low frequency component of the high frequency vibrator can be almost eliminated by the characteristics of the ultrasonic vibrator. On the other hand, in the case of the CPM, the low frequency and the high frequency cannot be distinguished by the ultrasonic vibrator, so that the separation depends on the transmitting / receiving circuit. However, in the current configuration, the low frequency cannot be completely cut, and the resolution degrades due to the low frequency component.
[0007]
Here, conventionally, as an ultrasonic diagnostic apparatus, there is a technique for changing the transmission waveforms of the CPM and the PZT of the ultrasonic transducer. In this case, even if the transmission waveforms of the CPM and the PZT are changed, the CPM does not cover a wide band. (See, for example, Patent Document 2).
[0008]
As an ultrasonic diagnostic apparatus, there is a technique in which a filter for receiving an electric signal from a CPM is switched and used. With this technique, it is possible to realize exactly the same performance as that of the PZT. Cannot receive an image with high image quality at high frequency and create an image with deepness at low distance using long frequency (for example, see Patent Document 3).
[0009]
To cope with this, there is a technique for utilizing the variable filter using a variable capacitor (varicap diode) to exhibit the above-described characteristics of the CPM (for example, see Patent Document 4). However, in this technique, at the limit of the variable capacitance, the Q value is lower than that of the fixed filter, and as a result, the low frequency component cannot be completely removed on the high frequency side.
[0010]
Further, in the conventional PZT, when using a high-frequency ultrasonic vibrator, the aperture is made one size smaller than that of a low-frequency ultrasonic vibrator, so that the focal point is set at a short distance and beam diffusion is prevented. However, in the CPM, since the aperture diameter is constant from low frequency to high frequency, on the high frequency side, the focus shifts to a distant place, the diffusion is fast, and the resolution in the azimuth direction is deteriorated (for example, see Patent Document 3).
[0011]
[Patent Document 1]
JP 2001-46379 A (page 3-4, FIG. 2)
[0012]
[Patent Document 2]
JP 2001-57978 A (page 4-7, FIG. 1-4)
[0013]
[Patent Document 3]
JP 2001-161682 A (page 3-4, FIG. 1)
[0014]
[Patent Document 4]
JP 2001-46379 A (page 5-6, FIG. 6-8)
[0015]
[Problems to be solved by the invention]
In such an ultrasonic diagnostic apparatus using a CPM (composite piezoelectric element) for the conventional ultrasonic vibrator, use of a wide band and cut of a low frequency on a high frequency side, which are characteristics of the CPM, cannot be achieved at the same time. There is a problem that an image having a low depth using a low frequency cannot be formed, or the resolution is deteriorated by a low frequency component on a high frequency side. Further, in the CPM, since the aperture diameter is constant from a low frequency to a high frequency, the focus shifts to a distant place on the high frequency side, the diffusion is fast, and the resolution in the azimuth direction is deteriorated.
[0016]
The present invention has been made in view of the above circumstances, and in an ultrasonic observation apparatus for diagnosing by exciting a composite piezoelectric element vibrator, an ultrasonic wave capable of using a wide band and improving the ultrasonic image quality on a high frequency side. It is intended to provide a diagnostic device.
[0017]
[Means for Solving the Problems]
An ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus according to claim 1 transmits and receives an ultrasonic wave to and from a subject to obtain an ultrasonic echo signal, and a first piezoelectric vibrator of the composite piezoelectric vibrator. A first frequency supply unit capable of supplying a drive signal of a first frequency to a portion, and a second frequency capable of supplying a drive signal of a second frequency to a second portion of the composite piezoelectric vibrator Supply means, one of the first frequency supply means and the second frequency supply means or a transmission selection means selectable at the same time, and the first frequency supply means driving the composite vibrator. First STC processing means for performing STC processing on the obtained ultrasonic echo signal, and second STC processing means for performing STC processing on the ultrasonic echo signal obtained by driving the composite vibrator by the second frequency supply means And the first ST A synthesizing means for synthesizing the output from the processing means and an output from the second STC processing means, characterized by comprising a.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment)
1 to 8 relate to an embodiment of the ultrasonic diagnostic apparatus of the present invention, FIG. 1 is a block diagram showing a circuit configuration of the ultrasonic diagnostic apparatus, FIG. 2 is a plan view showing a positive electrode of the ultrasonic transducer, and FIG. 3 is a graph showing a frequency characteristic of an output pulse of the pulse generation unit, FIG. 4 is a graph showing a frequency characteristic of an output pulse having passed through the first resonance inductor, and FIG. 5 is an output pulse having passed through the second resonance inductor. FIG. 6 is an explanatory diagram showing a first setting of the first and second STC circuits, and FIG. 7 is an explanatory diagram showing a second setting of the first and second STC circuits. FIG. 8 is an explanatory diagram showing a third setting of the first and second STC circuits.
[0019]
(Constitution)
As shown in FIG. 1, the ultrasonic diagnostic apparatus 1 includes a pulse generator 10, first and second switches 11 and 12, first and second pulse drivers 13 and 14, and first and second pulse drivers 13 and 14. , An ultrasonic vibrator 20 using a CPM (composite piezoelectric material) vibrator, first and second Sensitivity Time Control (STC) circuits 31, 32, and a reception synthesis unit. 33, a reception processing unit 34, and a monitor 35.
[0020]
Here, the STC circuit is also called an automatic sound wave attenuation correction circuit in the ultrasonic diagnostic apparatus.
[0021]
Further, the first switch 11, the first pulse driver 13, the first resonance inductor 15, the first positive electrode 21 of the ultrasonic vibrator 20, and the first STC circuit 31 It is a system A1 and corresponds to the low frequency side (for example, about 3 MHz to 10 MHz).
[0022]
The second switch 12, the second pulse driver 14, the second resonance inductor 16, the second positive electrode 22 of the ultrasonic vibrator 20, and the second STC circuit 32 are connected to the second system A2. And corresponds to the high frequency side (for example, about 10 MHz to 25 MHz).
[0023]
Hereinafter, the present embodiment will be described in more detail.
The ultrasonic diagnostic apparatus 1 generates a pulse including the frequency of the first system A1 and the frequency of the second system A2 in the internal pulse generator 10.
[0024]
The output line of the pulse generator 10 branches into two systems and is connected to one terminal of the first and second switches 11 and 12, respectively. The other terminals of the first and second switches 11 and 12 are connected to first and second pulse drivers 13 and 14, respectively.
[0025]
The first and second pulse drivers 13 and 14 amplify pulse signals from the first and second switches 11 and 12, respectively, and output the amplified signals from respective output terminals.
[0026]
The output terminals of the first and second pulse drivers 13 and 14 pass through the first and second resonance inductors 15 and 16 having different values, respectively, and are connected to the first and second resonance inductors 15 and 16 of the ultrasonic transducer 20 inside the ultrasonic endoscope. The first and second positive electrodes 21 and 22 are connected respectively.
[0027]
The first and second positive electrodes 21 and 22 are divided into two at the vibration surface of the ultrasonic transducer 20.
[0028]
The ultrasonic transducer 20 has a structure in which first and second positive electrodes 21 and 22 are formed on one surface of a piezoelectric element 23, and a negative electrode 24 is formed on the other surface of the piezoelectric element 23. The negative electrode 24 is connected to a negative electrode of the pulse generator 10 via a wiring (not shown).
[0029]
A wiring is branched from between the first resonance inductor 15 and the first pulse driver 13, and the input terminal of the first STC circuit 31 is connected to the branched wiring.
[0030]
A wiring is branched from between the second resonance inductor 16 and the second pulse driver 14, and an input terminal of the second STC circuit 32 is connected to the branched wiring.
[0031]
The ultrasonic wave received by the ultrasonic transducer 20 is converted into an electric signal, and from the first and second positive electrodes 21 and 22 through the first and second resonance inductors 15 and 16, respectively, to the first and second positive electrodes 21 and 22, respectively. , And are temporally weighted.
[0032]
Outputs of the first and second STC circuits 31 and 32 are combined into one system by a reception combining unit 33, and signal processing is performed by a reception processing unit 34.
[0033]
The signal processed by the reception processing unit 34 is displayed on a monitor 35.
As shown in FIG. 2, the first and second positive electrodes 21 and 22 of the ultrasonic transducer 20 are divided by concentric circles. The first positive electrode 21 is outside the concentric circle, and the second positive electrode 22 is inside the concentric circle.
[0034]
With such a structure, the ultrasonic vibrator 20 is a composite piezoelectric vibrator that transmits and receives ultrasonic waves to and from a subject to obtain an ultrasonic echo signal. The first and second positive electrodes 21 and 22 of the ultrasonic vibrator 20 are the first and second portions of the composite piezoelectric vibrator, respectively.
[0035]
The first pulse driver 13 and the first resonance inductor 15 are first frequency supply means capable of supplying a first frequency drive signal to the first portion of the composite piezoelectric vibrator. .
[0036]
The second pulse driver 14 and the second resonance inductor 16 serve as second frequency supply means capable of supplying a drive signal of a second frequency to a second portion of the composite piezoelectric vibrator. .
[0037]
The first and second switches 11 and 12 are transmission selection means that can select one of the first frequency supply means and the second frequency supply means or simultaneously.
[0038]
The first STC circuit 31 is a first STC unit that performs an STC process on an ultrasonic echo signal obtained by driving the composite vibrator by the first frequency supply unit.
[0039]
The second STC circuit 32 serves as second STC processing means for performing STC processing on an ultrasonic echo signal obtained by driving the composite vibrator by the second frequency supply means.
[0040]
The reception combining unit 33 is a combining unit that combines the output from the first STC processing unit and the output from the second STC processing unit.
[0041]
(Action)
Hereinafter, the operation of the present embodiment will be described.
S1 shown in FIG. 3 is a frequency characteristic of the output pulse of the pulse generator 10, and indicates that the pulse generator 10 is transmitting a broadband pulse.
[0042]
S2 shown in FIG. 4 is a frequency characteristic after the pulse of the pulse generation unit 10 has passed through the first resonance inductor 15 on the first system A1 side, and has passed through the first resonance inductor 15. This indicates that the subsequent pulse becomes a narrow-band low-frequency pulse.
[0043]
S3 shown in FIG. 5 is a frequency characteristic after the pulse of the pulse generation unit 10 has passed through the second resonance inductor 16 on the second system A2 side, and has passed through the second resonance inductor 16. This indicates that the subsequent pulse becomes a narrow-band high-frequency pulse.
[0044]
That is, FIGS. 4 and 5 show that the first resonance inductor 15 side is set to a low frequency, and the second resonance inductor 16 side is set to a high frequency.
[0045]
Next, a specific operation in the embodiment will be described.
In the first mode (low-frequency mode), the first switch 11 of FIG. 1 is turned on (connected), the second switch 12 is turned off (intermittent), and the first and second STC circuits 31 and 32 are turned on. Are set as shown in FIG. As a result, a low-frequency transmission pulse is transmitted from the outside of the ultrasonic transducer 20 (outside of the dotted line in FIG. 2) by the first resonance inductor 15 of FIG.
[0046]
According to the setting in FIG. 6, the amplification degree on the first STC circuit 31 side becomes larger than the amplification degree on the second STC circuit 32 side, so that the ultrasonic wave from the ultrasonic vibrator 20 passes through the first resonance inductor 15 side. The low-frequency signal is amplified, and the high-frequency signal that has passed from the ultrasonic transducer 20 to the second resonance inductor 16 is attenuated. For this reason, the high frequency component is hardly mixed in the signal input to the reception processing unit 34, and an image having a deep depth to the low frequency component can be obtained. Further, the band on the high frequency side is set so as to be an integral multiple of the low frequency side, and the settings of the first and second STC circuits 31 and 32 are shown in FIG. By receiving at an integer multiple (for example, twice) high frequency, it can be applied to harmonic images.
[0047]
In the second mode (broadband mode), both the first and second switches 11 and 12 of FIG. 1 are turned on (connected) simultaneously or almost simultaneously, and the settings of the first and second STC circuits 31 and 32 are changed. The setting is changed to the state shown in FIG. Thereby, low-frequency and high-frequency transmission pulses are simultaneously transmitted from the outside and the inside of the ultrasonic transducer 20 by the first and second resonance inductors 15 and 16 in FIG.
[0048]
According to the setting in FIG. 7, the amplification on the first STC circuit 31 side becomes smaller than the amplification degree on the second STC circuit 32 side in a portion relatively close to the ultrasonic transducer 20, and At a distant site, the amplification of the first and second STC circuits 31 and 32 gradually changes with time so that the amplification on the first STC circuit 31 side becomes larger than the amplification degree on the second STC circuit 31 side. Let it.
[0049]
For this reason, ultrasonic reception uses an image on the high frequency side received near the center of the ultrasonic transducer 20 in a part relatively close to the ultrasonic transducer 20, and uses a low frequency image in a part relatively far from the ultrasonic transducer 20. Use the side image. As a result, a high-resolution image can be obtained at a portion close to the ultrasonic transducer 20 and an image having a deep depth can be obtained.
[0050]
In the third mode (high frequency mode), the first switch 11 of FIG. 1 is turned off (intermittent), the second switch 12 is turned on (connected), and the first and second STC circuits 31 and 32 are turned off. The setting is changed to the state shown in FIG. As a result, a high-frequency transmission pulse is transmitted from the central portion of the ultrasonic transducer 20 (inside of the dotted line in FIG. 2) by the second resonance inductor 16 in FIG. For this reason, the aperture diameter of the ultrasonic transducer 20 can be made smaller than before.
[0051]
8, the amplification on the side of the second STC circuit 32 becomes larger than the amplification on the side of the first STC circuit 31. Therefore, the low frequency passing from the ultrasonic vibrator 20 to the side of the first resonance inductor 15 is reduced. The signal is attenuated, and the high-frequency signal that has passed from the ultrasonic transducer 20 to the second resonance inductor 16 is amplified. Therefore, the low-frequency component is hardly mixed into the signal input to the reception processing unit 34, and the image on the high frequency side is improved.
[0052]
(effect)
As described above, according to the present embodiment, in an ultrasonic observation apparatus that performs diagnosis by exciting a CPM oscillator, it is possible to use a wide band and improve ultrasonic image quality on a high frequency side. The versatility of the ultrasonic observation apparatus that performs diagnosis by performing diagnosis can be improved. By setting the high-frequency band to be an integral multiple of the low-frequency band, it can be applied to harmonic images.
[0053]
FIG. 9 is a circuit diagram showing a modified example of the embodiment of FIG. 1, and shows a part changed from FIG.
[0054]
In the ultrasonic diagnostic apparatus 1 shown in FIG. 1, the first and second resonance inductors 15 and 16 are connected in series to the ultrasonic vibrator 20, but the ultrasonic diagnostic apparatus of this modification shown in FIG. In the device 51, the first and second resonance inductors 55 and 56 are connected in parallel to the ultrasonic vibrator 20.
[0055]
More specifically, as shown in FIG. 9, the output terminals of the first and second pulse drivers 13 and 14 are directly connected to the first and second positive electrodes 21 and 22 of the ultrasonic transducer 20, respectively. At the same time, they are connected to the negative electrode 24 of the piezoelectric element 23 via first and second resonance inductors 55 and 56 having different values.
[0056]
A wiring is branched from between the first resonance inductor 55 and the first pulse driver 13, and an input terminal of the first STC circuit 31 is connected to the branched wiring.
[0057]
A wire is branched from between the second resonance inductor 56 and the second pulse driver 14, and the branched wire is connected to the input terminal of the second STC circuit 32.
[0058]
The other configuration of the ultrasonic diagnostic apparatus 51 is the same as that of the ultrasonic diagnostic apparatus 1 shown in FIG.
[0059]
With the ultrasonic diagnostic apparatus 51 of such a modified example, the same effects as those of the ultrasonic diagnostic apparatus 1 shown in FIG. 1 can be obtained.
[0060]
[Appendix]
According to the embodiment of the present invention described in detail above, the following configuration can be obtained.
[0061]
(Additional Item 1) A CPM (composite piezoelectric body) vibrator that transmits and receives ultrasonic waves to and from the subject to obtain ultrasonic echo signals,
First frequency supply means capable of supplying a drive signal of a first frequency to the CPM vibrator;
Second frequency supply means capable of supplying a drive signal of a second frequency to the CPM vibrator;
Any one of the first frequency supply means and the second frequency supply means or a transmission selection means selectable simultaneously;
First STC means for performing STC processing on an echo signal obtained by driving the CPM vibrator by the first frequency supply means;
A second STC unit for performing a second STC process for performing an STC process on an echo signal obtained by driving the CPM vibrator by the second frequency supply unit;
Combining means for combining the output from the first STC means and the output from the second STC means;
An ultrasonic diagnostic apparatus comprising:
[0062]
(Additional Item 2) The positive electrode of the CPM vibrator is divided into two systems, one of which is connected to the first frequency supply means, and the other is connected to the second frequency supply means. Ultrasonic diagnostic equipment.
[0063]
【The invention's effect】
As described above, according to the present invention, in an ultrasonic observation apparatus that performs a diagnosis by exciting a composite piezoelectric element vibrator, it is possible to use a wide band and improve ultrasonic image quality on a high frequency side. Versatility can be improved. By setting the high-frequency band to be an integral multiple of the low-frequency band, it can be applied to harmonic images.
[Brief description of the drawings]
FIG. 1 is a block diagram of a transmission / reception unit inside an ultrasonic endoscope according to an embodiment of the present invention.
FIG. 2 is a plan view showing a positive electrode of the ultrasonic transducer according to the embodiment of the present invention.
FIG. 3 is a graph illustrating frequency characteristics of output pulses of a pulse generation unit according to a second embodiment of the present invention.
FIG. 4 is a graph showing frequency characteristics of an output pulse passing through a first resonance inductor according to the embodiment of the present invention.
FIG. 5 is a graph showing frequency characteristics of an output pulse passing through a second resonance inductor according to the embodiment of the present invention.
FIG. 6 is an explanatory diagram showing a first setting of first and second STC circuits according to the embodiment of the present invention.
FIG. 7 is an explanatory diagram showing a second setting of the first and second STC circuits according to the embodiment of the present invention.
FIG. 8 is an explanatory diagram showing a third setting of the first and second STC circuits according to the embodiment of the present invention.
FIG. 9 is a circuit diagram showing a connection between a resonance inductor and an ultrasonic transducer according to a modification of the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic diagnostic apparatus 10 ... Pulse generation parts 11 and 12 ... 1st and 2nd switch 13, 14 ... 1st and 2nd pulse driver 15, 16 ... 1st and 2nd resonance inductor 20 ... Ultra Sound transducers 21 and 22 First and second positive electrodes 23 Piezoelectric elements 24 Negative electrodes 31 and 32 First and second STC circuits 33 Reception synthesis unit 34 Reception processing unit 35 Monitor

Claims (1)

A composite piezoelectric vibrator for transmitting and receiving ultrasonic waves to and from the subject to obtain ultrasonic echo signals,
First frequency supply means capable of supplying a first frequency drive signal to a first portion of the composite piezoelectric vibrator;
Second frequency supply means capable of supplying a drive signal of a second frequency to a second portion of the composite piezoelectric vibrator;
A transmission selection unit that can select any one of the first frequency supply unit and the second frequency supply unit or simultaneously;
First signal amplifying means for amplifying an ultrasonic echo signal obtained by driving the composite vibrator by the first frequency supply means;
Second signal amplifying means for amplifying an ultrasonic echo signal obtained by driving the composite vibrator by the second frequency supply means;
Combining means for combining an output from the first signal amplifying means and an output from the second signal amplifying means;
An ultrasonic diagnostic apparatus comprising:

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