JP2011050537A - Ultrasonic probe and ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus improving the real-time property of the image display by a simple structure and obtaining a clear tomographic image from a shallow region to a deep region. <P>SOLUTION: The ultrasonic probe includes: a plurality of inorganic piezoelectric elements; a plurality of organic piezoelectric elements; an amplifier for amplifying the output of the respective organic piezoelectric elements; and a switching means for connecting a corresponding signal line to one of output terminals of the inorganic piezoelectric elements, the organic piezoelectric elements or the amplifier according to a switch control signal. The ultrasonic probe is configured to transmit drive signals for driving the inorganic piezoelectric elements or organic piezoelectric elements and receiving signals from the inorganic piezoelectric elements or the amplifier via the signal line. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus.

  An ultrasonic diagnostic apparatus is a medical imaging device that obtains a tomographic image of soft tissue in a living body in a minimally invasive manner from the body surface by an ultrasonic pulse reflection method. Compared to other medical imaging equipment, this ultrasound diagnostic device has features such as being smaller and cheaper, without exposure to X-rays, etc., being highly safe, and capable of blood flow imaging by applying the Doppler effect. Yes. Therefore, it is widely used in the circulatory system (cardiac coronary artery), digestive system (gastrointestinal), internal medicine system (liver, pancreas, spleen), urology system (kidney, bladder), and obstetrics and gynecology.

  Conventionally, such an ultrasonic diagnostic apparatus is called a harmonic imaging (HI) method in which a harmonic component generated by nonlinear propagation of ultrasonic waves is taken out, and an ultrasonic image is generated and displayed based on the harmonic component. Have been used.

  The harmonic imaging is a technique for detecting and imaging a harmonic component contained in an ultrasonic reception signal (for example, transmitting a 5 MHz ultrasonic wave and imaging with a 10 MHz harmonic wave). It was developed for the purpose of detecting sonic contrast agents more efficiently.

  The microbubbles have strong nonlinear scattering characteristics, and the scattered signal contains a higher harmonic component than that of the living tissue. Therefore, by detecting only this harmonic component, it is possible to visualize a minute blood flow (perfusion) that is normally buried in an echo from the surrounding tissue (fundamental wave).

  As a specific structure of an array-type ultrasonic probe used for harmonic imaging, an array-type ultrasound that separates the operation during transmission and reception of ultrasonic waves by separating the transmitting piezoelectric element and the receiving piezoelectric element. A probe has been proposed.

  It is desirable that the receiving piezoelectric element used in such an array type ultrasonic probe can receive a harmonic signal with high sensitivity. However, since the transmission / reception frequency of a piezoelectric element made of an inorganic piezoelectric element such as lead zirconate titanate depends on the thickness of the piezoelectric element, it is necessary to process the piezoelectric element more compactly as the received frequency becomes higher. It was difficult.

  In order to solve such a problem, a piezoelectric element for transmission and a sheet-like piezoelectric element for reception having a single layer or laminated structure of sheet-like piezoelectric ceramics are made into a single layer or laminated, and separate transmission and reception piezoelectric elements And a method of obtaining a highly sensitive ultrasonic probe by using a highly sensitive organic piezoelectric element material for reception (see Patent Documents 1, 2, and 3).

  In recent years, tissue harmonic imaging (THI) has attracted attention. This is focused on the image quality improvement effect of the harmonic imaging method, and is characterized in that any patient can obtain a high-contrast B-mode image with reduced noise, and is excellent in rendering the endocardium and the like. In the tissue harmonic imaging method, harmonics generated by so-called non-linearity of propagation in which transmitted ultrasonic waves “propagate” while being distorted in a living body are visualized.

  Since the amplitude of this harmonic is proportional to the propagation distance of the ultrasonic wave and the square of the sound pressure of the fundamental wave, it is concentrated on the central axis of the ultrasonic beam (region with high sound pressure). That is, it is possible to form a sharp ultrasonic beam having a narrow main lobe and a low side lobe level as compared with the case where the fundamental wave is used.

  In this way, in the tissue harmonic imaging method, a beam having a narrow beam width and a low side lobe level can be formed. Therefore, the azimuth resolution is improved by reducing the beam width, and the contrast resolution is improved by reducing the side lobe level. In particular, when a tissue harmonic imaging method is used when diagnosing a relatively deep part of a patient, a clear image with high resolution can be obtained. On the other hand, when the region of interest is in a shallow region from the body surface, it may be difficult to obtain a clear image.

  On the other hand, in the method of transmitting the ultrasonic wave of the fundamental frequency to the subject and visualizing the inside of the subject mainly with the fundamental frequency component included in the reflected wave returned from the subject, it is as much as the tissue harmonic imaging method. Although a high-resolution image cannot be obtained, a clear diagnostic image can be obtained from a shallow part to a deep part in the subject.

  Therefore, a fundamental wave mode for transmitting an ultrasonic wave of the fundamental frequency to the subject and imaging the inside of the subject mainly with the fundamental frequency component included in the reflected wave returned from the subject, A non-fundamental wave mode in which the sound wave is transmitted to the subject and the inside of the subject is imaged mainly with the harmonic component contained in the reflected wave returned from the subject is selected. (For example, see Patent Document 4).

  On the other hand, when a high-frequency ultrasonic wave is transmitted to the subject and the reflected wave is received, the vicinity of the surface of the subject can be diagnosed with high resolution. For example, by using a sheet-like piezoelectric element made of an organic piezoelectric material for transmission and reception, a high frequency ultrasonic wave exceeding 20 MHz is transmitted, and a reflected wave (20 MHz) is received, thereby wide bandwidth and high resolution. Is disclosed (see Non-Patent Document 1).

  Since the piezoelectric element made of such an organic material has high output impedance, it is difficult to achieve impedance matching. Therefore, in Non-Patent Document 1, the amplifier is arranged near the piezoelectric element, and the received signal of the piezoelectric element is amplified by the amplifier and then A / D converted, thereby reducing parasitic capacitance and mixing of noise. Yes.

JP 2008-188415 A International Publication No. 2007/145073 Pamphlet International Publication No. 2008/010509 Pamphlet Japanese Patent No. 4116143 S. J Carey, C.I. M Gregory, M.M. P. Brewin, S.M. Ng, J .; V Hatfield, “PVdF Array Charactorization for High Frequency Ultrasonic Imaging” 2004 IEEE Ultrasonics and Frequency Control Joint Ace

  The user can select the optimal video method and obtain a clear image depending on whether the region of interest is a shallow part, deep part, or deep part of the subject. There is a need for an ultrasonic diagnostic apparatus.

  When interested in a deep part in the subject, as disclosed in Patent Documents 1, 2, and 3, a piezoelectric element made of an inorganic material (hereinafter referred to as an inorganic piezoelectric element) has a fundamental frequency (for example, 5 MHz). The ultrasonic wave is transmitted to the subject, the reflected wave returned from the subject is received by a piezoelectric element made of an organic material (hereinafter referred to as an organic piezoelectric element), and the harmonic component contained in the reflected wave is mainly used. It is known that a high-resolution diagnostic image can be obtained by imaging the inside of the subject.

  In addition, when interested in the whole image from a shallow part to a deep part in the subject, an ultrasonic wave of a fundamental frequency (for example, 5 MHz) is transmitted to the subject using an inorganic piezoelectric element for transmission and reception, and a reflected wave. It is known that a clear image can be obtained when the inside of a subject is imaged mainly with the fundamental frequency component included in.

  On the other hand, as in Non-Patent Document 1, when interested in a shallow part in the subject, an organic piezoelectric element is used for transmission and reception, and a high-frequency ultrasonic wave is transmitted to the subject and the reflected wave is received. It is known that a high-resolution diagnostic image can be obtained.

  For these reasons, it is conceivable that an inorganic piezoelectric element and an organic piezoelectric element are arranged on the ultrasonic probe so that the piezoelectric element used for transmission / reception can be selected according to the region of interest.

  However, when an inorganic piezoelectric element and an organic piezoelectric element are provided on the ultrasonic probe, the driving conditions and the like are different, and therefore the wiring between the ultrasonic probe and the ultrasonic diagnostic apparatus main body increases.

  When the organic piezoelectric element is used for reception, it is desirable to amplify the output of the organic piezoelectric element with an amplifier as disclosed in Non-Patent Document 1. Therefore, when used for transmission and reception, it is necessary to separate and wire so that the drive signal applied to the organic piezoelectric element is not applied to the output side of the amplifier.

  Since it is desirable to arrange the amplifier near the organic piezoelectric element of the ultrasonic probe, the amplifier is sent between the amplifier arranged in the ultrasonic probe and the receiving circuit provided in the ultrasonic diagnostic apparatus body. It is necessary to wire separately from the credit wiring. For this reason, the cable between the ultrasonic probe and the ultrasonic diagnostic apparatus main body becomes thick, and operability problems such as difficulty in pressing the ultrasonic probe against a desired part of the subject occur. Further, the possibility of cable breakage or the like increases, and reliability is impaired.

  The present invention has been made in view of the above problems, and is configured to be able to select an optimum piezoelectric element for imaging a desired part, and has an excellent operability and high reliability. An object of the present invention is to provide an ultrasonic diagnostic apparatus having an ultrasonic probe.

  In order to solve the above problems, the present invention has the following characteristics.

1. An ultrasonic probe that transmits and receives ultrasonic waves,
A plurality of inorganic piezoelectric elements made of an inorganic material;
A plurality of organic piezoelectric elements made of organic materials;
A plurality of amplifiers for amplifying reception signals generated by the respective organic piezoelectric elements that have received the ultrasonic waves;
It has switching means each provided with a connection part to a plurality of signal lines for connecting to the ultrasonic diagnostic apparatus body,
The switching means is
A connection configuration in which the inorganic piezoelectric element and the connection portion are directly connected, a connection configuration in which the organic piezoelectric element and the connection portion are directly connected, and a connection between the organic piezoelectric element and the connection portion. An ultrasonic probe having a function of switching and connecting a connection form connected via the amplifier.

  2. 2. The ultrasonic probe according to 1 above, wherein the inorganic piezoelectric element and the organic piezoelectric element are laminated.

3. The organic piezoelectric element is
3. The ultrasonic probe as described in 1 or 2 above, which is formed using a vinylidene fluoride polymer or a vinylidene fluoride copolymer as a material.

4). In an ultrasonic diagnostic apparatus configured to transmit an ultrasonic wave inside a subject, receive a reflected wave, and visualize the inside of the subject,
The ultrasonic probe according to any one of 1 to 3,
Transmitting means for transmitting a drive signal for driving the inorganic piezoelectric element or the organic piezoelectric element via the signal line;
Receiving means for receiving the received signal via the signal line;
A control means for transmitting a switching control signal for switching a connection form of the switching means, and for controlling the switching means;
Have
The control means includes
An ultrasonic diagnostic apparatus, wherein the switching control signal is transmitted according to a setting to switch the connection of the switching means.

5). The control means includes
Applying a drive signal to the inorganic piezoelectric element and transmitting an ultrasonic wave toward the inside of the subject, the fundamental frequency of the drive signal included in the reflected wave reflected from the subject received by the inorganic piezoelectric element A first mode for controlling the inside of the subject to be imaged mainly with components;
After applying a drive signal to the inorganic piezoelectric element and transmitting an ultrasonic wave toward the inside of the subject, the switching means is switched, and the organic piezoelectric element receives and reflects from the subject amplified by the amplifier. A second mode for controlling the inside of the subject to be imaged mainly with a non-basic frequency component other than the fundamental frequency included in the reflected wave;
A drive signal having a frequency higher than the fundamental frequency is applied to the organic piezoelectric element to transmit an ultrasonic wave toward the inside of the subject, and the organic piezoelectric element receives and reflects from the subject amplified by the amplifier. A third mode for controlling to image the inside of the subject mainly using the high frequency component included in the reflected wave;
The ultrasonic diagnostic apparatus according to 4 above, wherein the ultrasonic diagnostic apparatus is configured to be settable.

  According to the present invention, switching means for switching a plurality of inorganic piezoelectric elements, a plurality of organic piezoelectric elements, and an amplifier for amplifying the output of each organic piezoelectric element to connect to the signal line on the ultrasonic probe. Therefore, the number of wires connected to the ultrasonic diagnostic apparatus can be reduced.

  Accordingly, there is provided an ultrasonic probe that is configured to be able to select an optimum piezoelectric element for imaging a desired part, has high operability and high reliability, and an ultrasonic diagnostic apparatus having the ultrasonic probe. be able to.

It is a figure which shows the external appearance structure of the ultrasound diagnosing device in embodiment. It is a block diagram which shows the electrical structure of the ultrasonic diagnosing device in embodiment. It is a detailed circuit block diagram of an ultrasonic probe, a transmission processing unit, and a reception processing unit in the embodiment. It is sectional drawing of the head part of the ultrasonic probe in embodiment. It is a figure which shows each focus area | region set by the multistage focus method. It is a figure which illustrates typically until an ultrasonic wave is transmitted to the focus of each focus area | region, and is received. It is a time chart explaining the timing of transmission / reception. It is an example which comprised the switching means combining the single pole single throw analog switch.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiment. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

  FIG. 1 is a diagram illustrating an external configuration of an ultrasonic diagnostic apparatus according to an embodiment.

  The ultrasonic diagnostic apparatus 100 transmits ultrasonic waves (ultrasound signals) to a subject such as a living body (not shown) and reflects the reflected ultrasonic waves (echoes, ultrasonic signals) reflected by the received subject. The internal state in the subject is imaged as an ultrasound image and displayed on the monitor 10.

  The ultrasonic probe 2 transmits an ultrasonic wave (ultrasonic signal) to the subject and receives a reflected wave of the ultrasonic wave reflected by the subject. As shown in FIG. 1, the ultrasonic probe 2 is connected to an ultrasonic diagnostic apparatus main body 14 via a cable 15.

  The input unit 13 includes a switch, a keyboard, and the like. The input of the command for the user to start diagnosis, selection of the first mode, the second mode, or the third mode, which will be described later, and the individual of the subject It is provided to input data such as information.

  The monitor 10 is composed of a liquid crystal panel or the like, and displays an imaged ultrasonic image.

  FIG. 2 is a block diagram showing an electrical configuration of the ultrasonic diagnostic apparatus according to the present embodiment. FIG. 3 is a detailed circuit block diagram of the ultrasonic probe, transmission processing unit, and reception processing unit in the embodiment. FIG. 4 is a cross-sectional view of the head portion of the ultrasonic probe in the embodiment.

  First, the configuration of the ultrasonic probe 2 will be described with reference to FIGS. 2, 3, and 4.

  As shown in FIG. 3, a plurality of inorganic piezoelectric elements 50 a to 50 u arranged in an array for mutual conversion between an electric signal and an acoustic signal are arranged at the tip of the ultrasound probe 2. A plurality of organic piezoelectric elements 51a to 51u arranged are stacked. The inorganic piezoelectric elements 50a to 50u are piezoelectric elements made of an inorganic material, and the organic piezoelectric elements 51a to 51u are piezoelectric elements made of an organic material. In the following description, it is assumed that one piezoelectric element constitutes one channel. Moreover, although the number of elements of each of the inorganic piezoelectric element 50 and the organic piezoelectric element 51 is 21, and an example in which the number is distinguished by a to u will be described, the number of elements is not particularly limited, and the number of elements is about 20 to 200. Used.

  In FIG. 2, the inorganic piezoelectric element array 50 composed of a plurality of inorganic piezoelectric elements 50 a to 50 u and the organic piezoelectric element array 51 composed of a plurality of organic piezoelectric elements 51 a to 51 u are illustrated as one block.

  Since the organic piezoelectric elements 51a to 51u have a very high impedance of several KΩ, they are easily affected by noise. Therefore, the organic piezoelectric elements 51a to 51u are connected to the amplifiers 52a to 52u, respectively. The amplifiers 52a to 52u are electric signals (hereinafter referred to as reception signals) generated by the organic piezoelectric elements 51a to 51u that have received ultrasonic waves. Amplify). The received signals can be transmitted to the ultrasonic diagnostic apparatus main body 14 with high S / N by amplifying the received signals by the amplifiers 52a to 52u and outputting them with low impedance.

  As the amplifiers 52a to 52u, general-purpose amplifiers having high input impedance such as operational amplifiers using FETs (field effect transistors) in the first stage can be used.

  Signal lines 56a to 56u for connecting to the ultrasonic diagnostic apparatus main body 14 are connected to the connection portions 58a to 58u of the switching means 53, respectively.

  The switches 53a to 53u of the switching means 53 are connected in a direct connection between the inorganic piezoelectric elements 50a to 50u and the connection portions 58a to 58u in accordance with a switching control signal transmitted by the switching control signal line 57. A connection configuration in which the piezoelectric elements 51a to 51u and the connection portions 58a to 58u are directly connected, and a connection configuration in which the organic piezoelectric elements 51a to 51u and the connection portions 58a to 58u are connected via the amplifiers 52a to 52u. , Switch to connect.

  The single-pole three-throw switches 53a to 53u shown in FIG. 3 can be configured equivalently by combining a single-pole single-throw analog switch or the like and appropriately turning on or off by a switching control signal. it can.

  FIG. 8 shows an example in which the switching means 53 is configured by combining four single-pole single-throw analog switches 110a, 111a, 112a, and 113a.

  FIG. 8 shows a circuit for one channel corresponding to the switch 53a. Switching control signal lines 57a, 57b, 57c, and 57d are connected to the analog switches 110a, 111a, 112a, and 113a, respectively, and are turned on and off according to the transmitted switching control signal.

  In the state of FIG. 8, the analog switch 110a is on, the analog switches 111a, 112a, and 113a are off, and the inorganic piezoelectric element 50a and the connection portion 58a are directly connected. When the analog switch 110a is turned off, the analog switch 111a and the analog switch 112a are turned on, and the analog switch 113a is turned off by the switching control signal, the organic piezoelectric element 51a and the connection portion 58a can be directly connected.

  Further, when the analog switch 110a is turned off, the analog switch 111a and the analog switch 113a are turned on, and the analog switch 112a is turned off by the switching control signal, the organic piezoelectric element 51a and the connection portion 58a can be connected via the amplifier 52a. .

  Since the wiring between the organic piezoelectric elements 51a to 51u and the amplifiers 52a to 52u and the wiring between the organic piezoelectric elements 51a to 51u and the switches 53a to 53u are high impedance, the wiring length is shortened as much as possible, and a coaxial cable or a shielded cable is used. It is desirable not to be affected by external noise using

  In FIG. 2, the amplifiers 52 a to 52 u are illustrated as blocks of the amplifier 52, and the switches 53 a to 53 u are illustrated as blocks of the switching unit 53.

  The signal lines 56 a to 56 u and the switching control signal line 57 are connected to the connector 54, and are connected to the connector 16 of the ultrasonic diagnostic apparatus main body 14 via the cable 15. As described above, the switching means 53 connects the corresponding signal lines 56a to 56u to any one of the output terminals of the inorganic piezoelectric elements 50a to 50u, the organic piezoelectric elements 51a to 51u, or the amplifiers 52a to 52u. The number of wirings by the cable 15 can be reduced. Thereby, since the cable 15 can be made thin, the operability and reliability of the ultrasonic probe 2 can be improved.

  Next, the configuration of the head portion of the ultrasonic probe will be described with reference to FIG.

  In the following description, description will be made based on the coordinate axes indicated by X, Y, and Z in the drawing. The X direction is the elevation direction (the dicing direction), and the Z-axis positive direction is the direction in which ultrasonic waves are transmitted. The Z-axis direction is the stacking direction.

  The ultrasonic probe 1 shown in FIG. 4 includes a fourth electrode 75, an inorganic piezoelectric film 62, a third electrode 74, an intermediate layer 73, a second electrode 70, an organic piezoelectric film 63, and a first electrode on a backing material 65. 69, the matching layer 66, and the acoustic lens 67 are laminated in this order. The matching layer 66 to the fourth electrode 75 are diced in the X direction to form a plurality of inorganic piezoelectric elements 50a to 50u and organic piezoelectric elements 51a to 51u.

  Hereinafter, each component will be described in the order in which they are stacked.

(Inorganic piezoelectric element array)
The inorganic piezoelectric element array 50 includes inorganic piezoelectric elements 50a to 50 each having a third electrode 74 and a fourth electrode 75 on both surfaces of the inorganic piezoelectric film 62 made of an inorganic material such as lead zirconate titanate, which face each other in the thickness direction. 50u. The thickness of the inorganic piezoelectric film 62 is about 320 μm.

  The third electrodes 74a to 74u of the inorganic piezoelectric elements 50a to 50u are connected to the terminals of the switches 53a to 53u via connectors (not shown), and the fourth electrodes 75a to 75u are grounded.

  When a drive signal is applied to the third electrodes 74a to 74u, the inorganic piezoelectric elements 50a to 50u vibrate, and an ultrasonic wave is transmitted from the inorganic piezoelectric element array 50 in the positive Z-axis direction.

  Further, when the inorganic piezoelectric element array 50 receives and vibrates the reflected ultrasonic wave reflected by the subject, an electrical signal (hereinafter referred to as a received signal) is generated in the third electrodes 74a to 74u according to the reflected wave. .

  The third electrode 74 and the fourth electrode 75 are formed by vapor deposition or photolithography on both surfaces of the inorganic piezoelectric element array 50 using a metal material such as gold, silver, or aluminum.

(Middle layer)
The intermediate layer 73 vibrates the organic piezoelectric element array 51 so that the inorganic piezoelectric element array 50 does not resonate and vibrate when the organic piezoelectric element array 51 receives and vibrates the reflected ultrasonic wave reflected by the subject. Is provided to absorb.

  Such an intermediate layer 73 can be formed by molding a resin material. Examples of the resin material used for the intermediate layer 73 include polyvinyl butyral, polyolefin, polyacrylate, polyimide, polyamide, polyester, polysulfone, epoxy, and oxetane.

  The thickness of the intermediate layer 73 is selected depending on the required sensitivity and frequency characteristics, and is, for example, about 180 to 190 μm.

  Note that the intermediate layer 73 may be omitted depending on the sensitivity and frequency characteristics to be obtained.

(Organic piezoelectric element array)
The organic piezoelectric element array 51 includes a plurality of organic piezoelectric elements 51a to 51u having first electrodes 69a to 69u and second electrodes 70a to 70u on both surfaces of an organic piezoelectric film 63 made of an organic material facing in the thickness direction. It is composed of

  As an organic material used for the organic piezoelectric film 63, for example, a polymer of vinylidene fluoride can be used. Further, for example, a vinylidene fluoride (VDF) copolymer can be used for the organic piezoelectric film 63. This vinylidene fluoride copolymer is a copolymer (copolymer) of vinylidene fluoride and other monomers. Examples of other monomers include ethylene trifluoride (TrFE) and tetrafluoroethylene (TeFE). Perfluoroalkyl vinyl ether (PFA), perfluoroalkoxyethylene (PAE), perfluorohexaethylene, and the like can be used.

  In general, a piezoelectric element made of a piezoelectric material such as lead zirconate titanate can receive only an ultrasonic wave having a frequency band about twice the frequency of the fundamental wave. For example, ultrasonic waves in a frequency band of about 3 to 5 times the frequency can be transmitted and received, which is suitable for widening the reception frequency band.

  The thickness t of the organic piezoelectric film 63 is appropriately set depending on the frequency of the ultrasonic wave to be received, the type of the organic piezoelectric material, and the like.

  Such an organic piezoelectric film 63 is cast from a solution of an organic piezoelectric material to form a film having a predetermined thickness, heated to be crystallized, and then molded into a sheet having a predetermined size. Make it.

  A first electrode 69 and a second electrode 70 are formed on both surfaces of the organic piezoelectric film 63 facing each other in the thickness direction (Z-axis direction).

  The first electrodes 69a to 69u of the organic piezoelectric elements 51a to 51u are respectively connected to the terminals of the switches 53a to 53u via connectors not shown, and the second electrodes 70a to 70u are grounded.

  When a drive signal is applied to the first electrodes 69a to 69u, the organic piezoelectric elements 51a to 51u vibrate, and ultrasonic waves are transmitted from the organic piezoelectric element array 51 in the positive direction of the Z axis.

  Further, when the organic piezoelectric element array 51 receives and vibrates the reflected wave of the ultrasonic wave reflected by the subject, an electrical signal is generated in the first electrodes 69a to 69u according to the reflected wave.

(Matching layer)
The matching layer 66 has an acoustic impedance intermediate between the acoustic impedance of the human body, which is one of the subjects, and the organic piezoelectric element array 51, and matches the acoustic impedance. The matching layer 66 can be formed by molding a resin material, for example.

  The material used for the matching layer 66 is preferably a material having an acoustic impedance of about 1.7 to 1.8 and a sound speed of 1300 m / sec to 2200 m / sec, which is close to that of the human body. For example, polymethylpentene can be used.

(Acoustic lens)
The acoustic lens 67 converges the ultrasonic wave transmitted from the inorganic piezoelectric element array 50 to a predetermined distance.

  Thus, since the inorganic piezoelectric element array 50 and the organic piezoelectric element array 51 are laminated, the ultrasonic probe 2 can be reduced in size.

  The explanation of the ultrasonic probe 2 has been described above.

  Next, the electrical configuration of the ultrasonic diagnostic apparatus main body 14 will be described with reference to FIGS.

  The signal lines 56a to 56u of the ultrasonic probe 2 are connected to the transmission processing unit 1 and the reception processing unit 3 through the connector 54, the cable 15, and the connector 16 as shown in FIGS. The switching control signal line 57 is connected to the control unit 99 as shown in FIGS. 2 and 3 via the connector 54, the cable 15, and the connector 16. The transmission processing unit 1 is a transmission unit of the present invention, and the reception processing unit 3 is a reception unit of the present invention.

  The control unit 99 includes a CPU 98 (central processing unit), a storage unit 96, and the like, reads a program stored in the storage unit 96 into the RAM 97, and controls each unit of the ultrasound diagnostic apparatus 100 according to the program. The storage unit 96 includes a RAM (Random Access Memory), a ROM (Read Only Memory), and the like.

  The control unit 99 sets the mode (first mode, second mode, or third mode) input from the input unit 13 by the operator in the transmission processing unit 1 and the reception processing unit 3.

  When the ultrasonic wave is transmitted, the control unit 99 switches the signal lines 56a to 56u to either the inorganic piezoelectric elements 50a to 50u or the organic piezoelectric elements 51a to 51u according to the set mode. Make it connected.

  The control unit 99 switches the switches 53a to 53u so that the signal lines 56a to 56u are connected to the inorganic piezoelectric elements 50a to 50u in the first mode and the second mode, and in the third mode, the signal line 56a. To 56u are connected to the organic piezoelectric elements 51a to 51u.

The transmission processing unit 1 is a drive subjected to delay processing so as to form an ultrasonic wave in a beam shape at a timing corresponding to the mode set by the control unit 99 and to converge at an arbitrary depth to form a focal point. A signal is applied to each channel of the ultrasonic probe 2 via the signal lines 56a to 56u. The transmission processing unit 1 applies a drive signal having a fundamental frequency f ₀ in the first mode and the second mode, and applies a drive signal higher than the fundamental frequency f ₀ in the third mode. In this embodiment, it is assumed that 3f _0, which is three times the fundamental frequency f ₀ , is applied to simplify the description.

  The ultrasonic wave generated by the ultrasonic probe 2 is transmitted to the subject, propagates inside the subject, is reflected by a discontinuous surface of the acoustic impedance in the middle thereof, and is echoed to the ultrasonic probe 2 as an echo. Come back.

  After transmitting the ultrasonic wave toward the subject, the echoes returned to the ultrasonic probe 2 are the inorganic piezoelectric elements 50a to 50u and the organic piezoelectric elements 51a to 51u arranged on the ultrasonic probe 2. Is mechanically vibrated to generate a weak received signal.

  When receiving the ultrasonic wave, the control unit 99 switches the switches 53a to 53u according to the set mode so that the signal lines 56a to 56u are the inorganic piezoelectric elements 50a to 50u or the organic piezoelectric elements 51a to 51u or the amplifiers 52a to 52a. 52u is connected.

  In the first mode, the control unit 99 causes the signal lines 56a to 56u to be connected to the inorganic piezoelectric elements 50a to 50u as they are even when the switches 53a to 53u receive signals. In the second mode and the third mode, the control unit 99 53a to 53u are switched so that the signal lines 56a to 56u are connected to the amplifiers 52a to 52u.

  The signals of the signal lines 56a to 56u at the time of ultrasonic reception are taken into the reception processing unit 3, amplified by the preamplifiers 42a to 42u, and then subjected to the reception beam former 41 subjected to the same delay processing as at the time of transmission. The addition unit 43 adds the values.

In the first mode, the received signal has a fundamental band pass filter whose pass band is set to a predetermined band centered on the fundamental frequency f ₀ in order to mainly extract a fundamental wave component from the received signal. (BPF) 4 is sent to the B-mode processing unit 6.

In the second mode and the third mode, the harmonic band-pass filter (BPF) 5 whose pass band is set to a predetermined band centered on, for example, a frequency that is three times the fundamental frequency f ₀ is used. And sent to the B-mode processing unit 6.

In the second mode, non-fundamental wave components other than the fundamental frequency f ₀ generated by so-called non-linearity of propagation are used, in which the ultrasonic waves included in the echo are 'propagated' while distorting the inside of the subject (living body). . Among the non-fundamental component, twice the second harmonic component of the fundamental frequency f _0, but a like three times the third harmonic component can be used for image formation for diagnosis, in the embodiment In the following description, it is assumed that a third harmonic component having a triple frequency 3f ₀ is used.

In the third mode, the present embodiment will be described on the assumption that an ultrasonic wave having a frequency 3f ₀ that is three times the fundamental frequency f ₀ is transmitted to the subject and the component having the same frequency 3f ₀ is used. .

The B mode processing unit 6 generates a normal B mode image based on the component of the fundamental frequency f ₀ from the fundamental band pass filter 4 in the first mode, and in the second mode and the third mode. In the mode, an image is generated based on a 3f ₀ component that is three times the fundamental frequency from the harmonic band-pass filter 5. These images are reconstructed by a digital scan converter (DSC) 9, converted into a video signal, and displayed on the monitor 10.

  Next, the multistage focus method will be described with reference to FIGS. 5, 6, and 7.

  FIG. 5 is a diagram illustrating an example of each focus region set by the multistage focus method, and FIG. 6 is a diagram schematically illustrating the process of transmitting and receiving ultrasonic waves to the focus of each focus region. FIG. 7 is a time chart for explaining an example of the transmission timing.

  In the present embodiment, a case will be described in which images of four focus areas E1, E2, E3, and E4 that are equally spaced in the depth direction of the living body (subject) shown in FIG. 5 are obtained.

  The transmission processing unit 1 forms ultrasonic waves in a beam shape, and sequentially applies drive signals that have been subjected to delay processing so as to form focal points in the focus regions E1, E2, E3, and E4, or inorganic piezoelectric elements 50a to 50u or organic piezoelectric elements. Applied to the elements 51a to 51u. The focus of the focus area E1 is F1, the focus of the focus area E2 is F2, the focus of the focus area E3 is F3, and the focus of the focus area E4 is F4. In the example of FIG. A focal point is formed on the center axis of 50u or organic piezoelectric elements 51a to 51u. The ultrasonic beams transmitted from the inorganic piezoelectric elements 50a to 50u or the organic piezoelectric elements 51a to 51u are spread again after converging at the positions of the respective focal points as shown in FIG.

  FIGS. 6B to 6E schematically illustrate the maximum time from when an ultrasonic wave is transmitted to each focal point until a harmonic generated near the focal point is received in the second mode. It shows. Harmonics are generated only in the focus area near the focal position. Since the generated harmonics have a higher attenuation factor than the fundamental wave, they do not travel and reflect deeper areas. Therefore, the maximum time is the time until the fundamental wave of the transmitted ultrasonic wave travels to the deeper boundary of each focus region, and the harmonic generated at the boundary returns to the ultrasonic probe 2.

  FIG. 6E shows a case where the wave is transmitted to the deepest focal point F4, where t is the maximum time until a harmonic generated near the deeper boundary of the focus region E4 is received. FIG. 6D shows a case where waves are transmitted to the focal point F3. When the focus areas are equally spaced, the maximum time required to receive harmonics generated near the deeper boundary of the focus area E3 is 3 /. 4t.

  Similarly, FIG. 6C shows a case where the wave is transmitted to the focal point F2, and FIG. 6B shows a case where the wave is transmitted to the focal point F1, and the harmonics generated near the deeper boundary of the focus region E2. Is 2/4 × t, and the maximum time until a harmonic generated near the deeper boundary of the focus area E1 is 1/4 × t.

  FIG. 7 is a time chart for explaining the transmission timing. The horizontal axis in FIG. 7 is a time axis and shows timing pulses generated by the transmission processing unit 1. A drive signal is transmitted to the inorganic piezoelectric elements 50a to 50u or the organic piezoelectric elements 51a to 51u at the rising edge of the timing pulse for each period t, and an ultrasonic wave is transmitted. T is a period for forming one screen.

  The transmission processing unit 1 applies a drive signal to the inorganic piezoelectric elements 50a to 50u or the organic piezoelectric elements 51a to 51u at the transmission timing shown in FIG.

  First, the transmission / reception timing in the first mode will be described.

  The controller 99 connects the switches 53a to 53u so that the signal lines 56a to 56u are connected to the inorganic piezoelectric elements 50a to 50u, and then the ultrasonic wave is converged to the closest focus F1 at the rising edge of the timing pulse of F1. Send a wave. During the period in which the reflected wave from the focus area E1 indicated by E1 in FIG. 7 is received, the signal received by the inorganic piezoelectric elements 50a to 50u is caused to be subjected to the same delay processing as that at the time of wave transmission. Similarly, ultrasonic waves are transmitted so as to converge to the focal points F2, F3, and F4 at the rising edges of the timing pulses of F2, F3, and F4.

  As described above, the signals received by the inorganic piezoelectric elements 50a to 50u during the periods E1, E2, E3, and E4 are added by the reception processing unit 3 through the same delay processing as that at the time of transmission, so that the bandpass filter for harmonics is used. 5, only the harmonic component is sent to the B-mode processing unit 6 to generate an image.

  Next, transmission / reception timing in the second mode will be described.

  The controller 99 connects the switches 53a to 53u so that the signal lines 56a to 56u are connected to the inorganic piezoelectric elements 50a to 50u, and then the ultrasonic wave is converged to the closest focus F1 at the rising edge of the timing pulse of F1. Send a wave. After about 1 μS after transmission, the control unit 99 switches the switches 53a to 53u so that the signal lines 56a to 56u are connected to the amplifiers 52a to 52u, and the signals received by the organic piezoelectric elements 51a to 51u during the period E1. The reception processing unit 3 is caused to perform the same delay processing as that during transmission.

  Next, the control unit 99 switches the switches 53a to 53u so that the signal lines 56a to 56u are connected to the inorganic piezoelectric elements 50a to 50u, and then converges to the focal point F2 at the rising edge of the timing pulse of F2. Send ultrasonic waves. After about 1 μS after transmission, the control unit 99 switches the switches 53a to 53u so that the signal lines 56a to 56u are connected to the amplifiers 52a to 52u, and the signals received by the organic piezoelectric elements 51a to 51u during the period E2. The reception processing unit 3 is caused to perform the same delay processing as that during transmission. Similarly, ultrasonic waves are transmitted from the inorganic piezoelectric elements 50a to 50u so as to converge to the focal points F3 and F4 at the rising edges of the timing pulses of F3 and F4, respectively, and during the period of E3 and E4, the reception processing unit 3 performs the amplifier 52a. Control to process ~ 52u output.

  In this way, the signals received by the organic piezoelectric elements 51a to 51u during the periods E1, E2, E3, and E4 are added by the reception processing unit 3 through the same delay processing as that at the time of transmission, and the harmonic band-pass type Through the filter 5, only the harmonic component is sent to the B-mode processing unit 6 to generate an image.

  Next, the transmission / reception timing in the third mode will be described.

  The control unit 99 causes the switches 53a to 53u to connect the signal lines 56a to 56u to the organic piezoelectric elements 51a to 51u, and then causes the ultrasonic waves to converge to the closest focus F1 at the rising edge of the F1 timing pulse. Send a wave. After about 1 μS after transmission, the control unit 99 switches the switches 53a to 53u to connect the signal lines 56a to 56u to the amplifiers 52a to 52u, and signals received by the organic piezoelectric elements 51a to 51u during the period E1. The reception processing unit 3 is caused to perform the same delay processing as that during transmission.

  Next, the control unit 99 switches the switches 53a to 53u so that the signal lines 56a to 56u are connected to the organic piezoelectric elements 51a to 51u, and then converges to the focal point F2 at the rising edge of the timing pulse of F2. Send ultrasonic waves. After about 1 μS after transmission, the control unit 99 switches the switches 53a to 53u so that the signal lines 56a to 56u are connected to the amplifiers 52a to 52u, and the signals received by the organic piezoelectric elements 51a to 51u during the period E2. The reception processing unit 3 is caused to perform the same delay processing as that during transmission. Similarly, ultrasonic waves are transmitted from the organic piezoelectric elements 51a to 51u so as to converge to the focal points F3 and F4 at the rising edges of the timing pulses of F3 and F4, respectively, and during the period of E3 and E4, the reception processing unit 3 performs the amplifier 52a. Control to process ~ 52u output.

  As described above, the signals received by the organic piezoelectric elements 51a to 51u during the periods E1, E2, E3, and E4 are added by the reception processing unit 3 through the same delay processing as that at the time of transmission, and the bandpass filter for harmonics is used. 5, only the harmonic component is sent to the B-mode processing unit 6 to generate an image.

  In the present embodiment, an example in which the first mode, the second mode, and the third mode are switched when the operator performs a mode switching operation with the input unit 13 has been described. You may make it switch automatically whenever it scans once, or whenever it transmits / receives once.

  For example, the shallowest focus area E1 may perform transmission / reception in the third mode, the focus areas E2, E3, and E4 may perform transmission / reception in the second mode, and the received signals may be added to generate an image. In this way, the shallow region transmits and receives in the third mode in which the high resolution is obtained in the shallow region, and the deep region transmits and receives in the second mode in which the high resolution is obtained in the deep region. A tomographic image is obtained.

  As described above, according to the present invention, an ultrasonic probe that is configured to be able to select a piezoelectric element that is optimal for imaging a desired part, has high operability and high reliability, and the ultrasonic probe. It is possible to provide an ultrasonic diagnostic apparatus having

DESCRIPTION OF SYMBOLS 1 Transmission processing part 2 Ultrasonic probe 3 Reception processing part 4 Bandpass filter for fundamental waves 5 Bandpass filter for harmonics 6 B mode processing part 9 Digital scan converter 10 Display part 13 Input part 14 Ultrasonic diagnostic apparatus Body 15 Cable 50 Inorganic piezoelectric element array 50a to 50u Inorganic piezoelectric element 51 Organic piezoelectric element array 51a to 51u Organic piezoelectric element 52 Amplifier 53 Switching means 53a to 53u Switch 56 Signal line 57 Switching control signal line 69 First electrode 70 Second electrode 74 3rd electrode 75 4th electrode 96 Memory | storage part 98 CPU
99 control unit 100 ultrasonic diagnostic apparatus

Claims (5)

An ultrasonic probe that transmits and receives ultrasonic waves,
A plurality of inorganic piezoelectric elements made of an inorganic material;
A plurality of organic piezoelectric elements made of organic materials;
A plurality of amplifiers for amplifying reception signals generated by the respective organic piezoelectric elements that have received the ultrasonic waves;
It has switching means each provided with a connection part to a plurality of signal lines for connecting to the ultrasonic diagnostic apparatus body,
The switching means is
A connection configuration in which the inorganic piezoelectric element and the connection portion are directly connected, a connection configuration in which the organic piezoelectric element and the connection portion are directly connected, and a connection between the organic piezoelectric element and the connection portion. An ultrasonic probe having a function of switching and connecting a connection form connected via the amplifier.   The ultrasonic probe according to claim 1, wherein the inorganic piezoelectric element and the organic piezoelectric element are laminated. The organic piezoelectric element is
3. The ultrasonic probe according to claim 1, wherein the ultrasonic probe is formed by using a vinylidene fluoride polymer or a vinylidene fluoride copolymer as a material. In an ultrasonic diagnostic apparatus configured to transmit an ultrasonic wave inside a subject, receive a reflected wave, and visualize the inside of the subject,
The ultrasonic probe according to any one of claims 1 to 3,
Transmitting means for transmitting a drive signal for driving the inorganic piezoelectric element or the organic piezoelectric element via the signal line;
Receiving means for receiving the received signal via the signal line;
A control means for transmitting a switching control signal for switching a connection form of the switching means, and for controlling the switching means;
Have
The control means includes
An ultrasonic diagnostic apparatus, wherein the switching control signal is transmitted according to a setting to switch the connection of the switching means. The control means includes
Applying a drive signal to the inorganic piezoelectric element and transmitting an ultrasonic wave toward the inside of the subject, the fundamental frequency of the drive signal included in the reflected wave reflected from the subject received by the inorganic piezoelectric element A first mode for controlling the inside of the subject to be imaged mainly with components;
After applying a drive signal to the inorganic piezoelectric element and transmitting an ultrasonic wave toward the inside of the subject, the switching means is switched, and the organic piezoelectric element receives and reflects from the subject amplified by the amplifier. A second mode for controlling the inside of the subject to be imaged mainly with a non-basic frequency component other than the fundamental frequency included in the reflected wave;
A drive signal having a frequency higher than the fundamental frequency is applied to the organic piezoelectric element to transmit an ultrasonic wave toward the inside of the subject, and the organic piezoelectric element receives and reflects from the subject amplified by the amplifier. A third mode for controlling to image the inside of the subject mainly using the high frequency component included in the reflected wave;
The ultrasonic diagnostic apparatus according to claim 4, wherein the ultrasonic diagnostic apparatus is configured to be settable.

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