JPH0443957A - Ultrasonic image pickup system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an imaging method of an ultrasound imaging device such as an electronic scanning type medical ultrasound diagnostic device or an ultrasound flaw detection device.
In particular, the present invention relates to an ultrasonic imaging method that is an improved version of the electronic scanning method.

[Conventional technology]

2. Description of the Related Art Conventionally, an ultrasonic imaging apparatus is known that emits ultrasonic pulses into a subject and receives echoes reflected from tissue boundaries to obtain a desired tomographic image on a display such as a cathode ray tube. In addition, by developing the above-mentioned ultrasonic imaging device and repeating the imaging of a tomographic plane obtained by electronic scanning by moving or deflecting it in the thickness direction, ultrasonic imaging is performed to image a three-dimensional region (stereoscopic) inside the subject. Sonic imaging devices have also been proposed. In the probe of such a three-dimensional ultrasound imaging device, lead zirconate titanate (PZT) is used as the transducer that transmits and receives ultrasound waves.
A method has been considered that uses a piezoelectric material such as ceramic porcelain and provides independent wiring for each two-dimensionally divided vibrator. However, this method is difficult to implement because it involves arranging a large number of microscopic vibrators, and the accompanying signal processing circuit system is also large-scale, making it virtually impossible to implement.

Therefore, in order to avoid this problem, as shown in Fig. 2(a), a rectangular electrode array is formed on each main surface of the vibrator flat plate, and the electrode arrays intersect with each other. Ultrasonic probes for this purpose have been proposed. In this vibrator, as shown in FIG. 2(b), the electrode Ai is
, Bj, and drive only the electrode intersection portion as one vibrating element. However, if a vibrator with crossed electrodes is made of piezoelectric material and an attempt is made to transmit and receive ultrasonic waves by driving only the intersecting portions of the electrodes,
Since areas other than the intersection of the transducers in contact with the selected electrodes Ai and Bj are electrically half-selected, there is a problem in that the selectivity of the drive region is reduced as a result, and this problem is difficult to perform in actual ultrasound imaging. When a transducer of this configuration is used, there is a problem in that the resolution of the obtained image is significantly lower than when the transducer is composed of independently two-dimensionally divided transducers.

Furthermore, in order to solve the problem of the decrease in selectivity mentioned above, a second
An ultrasonic probe that improves the selectivity of the drive region by using an electrostrictive material as the transducer material shown in Figure (a) was disclosed in Japanese Patent Application Laid-Open No. 62-8469.
It is disclosed in Publication No. 7. Piezoelectric materials, which are currently widely used as vibrator materials, utilize the property of generating voltage through mechanical displacement caused by the delivery of ultrasonic waves. On the other hand, electrostrictive materials have the property that, like piezoelectric materials, voltage fluctuations due to mechanical displacement occur only in the presence of a bias electric field. Furthermore, since the electromechanical coupling coefficient changes greatly depending on the strength of the bias electric field, the electrostrictive material can be regarded as a piezoelectric material whose electroacoustic conversion efficiency can be controlled by the bias electric field.

Using this electrostrictive material flat plate, as shown in Fig. 2(a),
A transducer 2 is provided with strip-shaped electrode arrays A and B that intersect with each other.
, the electrodes Ai and B selected from each main surface
By applying a bias electric field between j, fI42 diagram (
As shown in b), the electrostrictive material at the cross section with hatching is selected as the vibrating element 21, and ultrasonic waves are transmitted and received using the above-mentioned electrostrictive material vibrator 2 as voltage fluctuation between the electrodes. In an ultrasound imaging device equipped with a probe,
The electrode to which the bias voltage is applied and the electrode to which the ultrasound transmission/reception circuit is connected are selected, and the transducer 2 is selectively driven two-dimensionally to transmit and receive ultrasound, thereby performing three-dimensional imaging of the subject. be able to.

In a three-dimensional ultrasound imaging device that electronically performs ultrasound scanning using a probe equipped with such a transducer, in order to image a three-dimensional scanning area inside a subject with high resolution, it is necessary to
Because the number of times ultrasound is transmitted and received increases dramatically compared to the conventional two-dimensional B-mode tomographic image capture, it takes a relatively long time to complete one three-dimensional image, reducing the immediacy of imaging. There is a problem. From this, the conventional two-dimensional B
Similar to when taking mode tomographic images, when the examiner operates the position and orientation of the ultrasound probe and determines the optimal position while viewing the image on the display in real time, the third Diagram (a)
Pi-brane imaging as shown in Figure 1 is effective.

Pi-plane imaging, for example, alternately images two mutually orthogonal tomographic planes in real time. Figure 3 (b
), when imaging the entire imaging region V that is desired to be imaged within the subject, it is necessary to perform imaging centered on the region of interest O, which is a target or a reference for positional relationship. Therefore, while checking the tomograms of the two B-mode tomographic planes PL and P2 on the display in real time, as shown in the positional relationship shown in FIG. After determining the position and orientation of the probe so as to capture region 0, starting three-dimensional imaging, which requires a relatively long imaging time, is very effective in efficiently performing imaging.

Moreover, as shown in FIG. 3(b), the three-dimensional imaging method is
In the case of a scan in which imaging of tomographic plane PI or P2 is repeated by sequentially moving in the thickness direction, generally, the obtained Anisotropy occurs in the resolution of the entire imaging region V. For this reason, it is necessary to be able to select whether to set the electronic scanning direction toward the tomographic plane PI or P2, which provides higher resolution in three-dimensional imaging, without moving the probe position. become.

A method using a piezoelectric vibrator of the same type as that shown in FIG. 2(a) as an ultrasonic probe that enables the pie-brain imaging described above is
It is disclosed in Japanese Unexamined Patent Publication No. 57-68999. By using this ultrasound probe, two B-mode tomographic planes within the subject that intersect with each other (for example, orthogonal to each other) are imaged,
It is said that it is possible to construct an ultrasonic diagnostic apparatus that enables pie-lane imaging that is alternately displayed on a display in real time.

That is, the sector-type ultrasonic transmitting/receiving scanning circuit section is connected to the strip-shaped electrode array A on one main surface of the vibrator, and the strip-shaped electrode array on the other surface is connected to the transducer as a common ground side electrode. Drive.

After imaging two B-mode tomographic planes, the B-mode tomographic plane is imaged again with the connection to each electrode array alternated.

[Problem to be solved by the invention] The former of the above-mentioned prior art, that is, JP-A-62-8
Japanese Patent No. 4697 discloses the operating principle or basic configuration of an ultrasonic probe using an electrostrictive material vibrator with a crossed electrode array as an electroacoustic transducer. However, this does not take into consideration the fact that the pie-lane imaging described above is an effective and important method for three-dimensional imaging, and does not take into consideration the fact that the pie-lane imaging described above is an effective and important method for three-dimensional imaging. Three-dimensional imaging methods were not considered.

Moreover, the latter of the above-mentioned conventional techniques, that is,
Publication No. 7-68999 discloses a pie-brain 1! using an ultrasonic probe composed of a piezoelectric material vibrator with a crossed electrode arrangement. Only the image is disclosed, and the electronic scanning direction of an ultrasound probe using electrostrictive material is not considered. Ultimately, these techniques suffer from a decrease in the real-time performance of three-dimensional imaging and a difference in resolution. It is not a technology that takes imaging into account with orientation in mind, but rather an ultrasound imaging method that can easily determine the orientation of the probe with respect to the subject and that can practically perform three-dimensional imaging. There wasn't.

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in the conventional technology, and to use an electrostrictive material provided with crossed electrode arrays A and B in a vibrator. An object of the present invention is to provide an ultrasonic imaging system in which electronic scanning for imaging can be performed in either direction of the electrode arrays A and B in an ultrasonic imaging apparatus equipped with the used ultrasound probe.

Another object of the present invention is to provide the above-mentioned ultrasonic imaging device,
An object of the present invention is to provide an ultrasonic imaging method that can alternately image two tomographic planes that intersect at a certain angle and display them simultaneously in real time. Still another object of the present invention is to perform ultrasonic imaging in which the electronic scanning direction can be selected in consideration of the anisotropy of resolution when performing three-dimensional imaging of a subject in the above-mentioned ultrasonic imaging apparatus. The goal is to provide a method.

f Means for Solving the Problem] The above object of the present invention is to provide a plurality of strip-shaped electrodes that are perpendicular to each other or intersect at a certain angle on both main surfaces of a flat plate of an electrostrictive material in which piezoelectricity is induced by a bias electric field. An ultrasonic probe using an arrangement A and B as a transducer, a wave transmitting circuit connected to the ultrasonic probe, a delivery circuit, and a bias for inducing piezoelectricity in the electrostrictive material. In an ultrasonic imaging device equipped with a voltage application circuit, a switch scanning circuit is added between each of the electrode arrays A and B and the wave transmitting circuit, the delivery circuit, and the bias voltage application circuit, and the switch scanning circuit is connected. This is achieved by an ultrasonic imaging method characterized in that, by modification, electronic scanning of ultrasonic transmission and reception can be performed arbitrarily by either of the electrode arrays A and B.

[Function] As mentioned above, electrostrictive materials have the property of causing voltage fluctuations due to mechanical displacement only under a bias electric field.
It can be regarded as a piezoelectric material whose conversion efficiency can be controlled by a DC bias electric field. As shown in FIG. 2(a), a rectangular electrode array A is arranged so as to intersect (for example, orthogonally) with each other on the main surface of a planar electrostrictive material.

Provide B. Here, the electrode arrays A and B have exactly the same shape except that they intersect with each other. If an ultrasonic pulse transmitting circuit and a receiving circuit are connected to electrode array A through one of the switch circuits for selecting electrodes, and a bias voltage application circuit is connected to electrode array B through the other switch circuit, Depending on the state of the switch circuit connected to electrode arrays A and B, 1! is connected to the bias voltage application circuit. A bias voltage is applied between the pole and the electrode facing it, inducing piezoelectricity, so that only the intersections of the selected electrodes transmit and receive ultrasound.

In the ultrasonic probe equipped in an electronic scanning type ultrasonic imaging device, the transducer is divided in at least one axial direction, and the ultrasonic wave is focused using an electronic focusing method. The circuits connected to arrays A and B can be alternated with each other by the above-mentioned switch circuit.

When converging ultrasonic waves using the electronic focusing method, the azimuth direction in which convergence is possible is determined by the dividing direction of electrode array A or B connected to the wave transmitting circuit and the delivery circuit. Correspondingly, since the electronic scanning direction of one tomographic plane is also determined, the circuits connected to the electrode arrays A and H are alternated by the above-mentioned switch circuit, so that the electronic scanning direction for tomographic imaging is determined. Also, the arrangement directions of electrode arrays A and B form an angle with each other, for example, orthogonal directions. As a result, the tomographic planes to be imaged also intersect with each other, making it possible to image two perpendicular tomographic planes (pie lanes) PI and P2 as shown in FIG. 3(a).

In addition, in the above configuration, as shown in FIG. 3(b), B
When performing three-dimensional imaging by scanning a mode tomographic image in a direction intersecting the plane, in order to image the region V inside the subject, one scans the tomographic plane P1 and the other scans the tomographic plane P2. It is possible to select. By sequentially moving or deflecting the images of the tomographic plane and repeating them multiple times,
Although a three-dimensional region can be imaged, the resolution of each tomographic image differs in the azimuth direction and the thickness direction of the tomographic plane depending on the imaging method. Therefore, the azimuth direction in which the resolution of the obtained three-dimensional area image increases depends on which of the electrode arrays A and B is used to perform electronic scanning of the tomographic plane. , the operator can change the alternate connection state of the switch circuits described above using a changeover switch provided on the ultrasonic probe, the imaging device main body, or an extension of the main body.

C Embodiment] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

For example, compositions (1
! The vibrator material is a rectangular plate of a strain-strain type ceramic composition, or a composite in which the space between arranged columnar objects of the porcelain composition is filled and held with a resin or the like.

Then, the material is processed into a vibrator so that the resonant frequency in the thickness direction corresponds to the frequency of the ultrasonic waves to be emitted or received. As shown in FIG. 2(a), electrode arrays A and B each divided into a plurality of strips are formed on each main surface of the rectangular plate of the electrostrictive vibrator 2 created as described above. .

The electrodes may be formed, for example, by electroless plating of copper, nickel, or the like, or vapor deposition of gold, copper, or the like. The electrode arrays A and B formed on both main surfaces are formed such that the electrode dividing directions on the two surfaces are perpendicular to each other. Further, the shapes of the electrodes A and B are completely the same.

FIG. 1 is a configuration diagram of the vicinity of an ultrasound probe in an ultrasound imaging apparatus according to an embodiment of the present invention.

In the electrostrictive vibrator 2 provided with the above-described electrode arrays A and B, the electrode arrays A and B are connected to electronic scanning type switch scanning circuits 14a and +4b, respectively. Transmitting circuit II, receiving circuit 12. Each of the bias voltage application circuits 13 is a switch scanning circuit 14a.

+4b. Transmitting circuit +1 and receiving circuit 12
And the bias voltage application circuit 13 is set to 1! in either one of the switch scanning circuits 14a and 1.4b. Polar arrangement A
or B, and the switch scanning circuit 14a,
Depending on the operating state of 14b, the connection to electrode array A or B can be alternated. Further, the wave transmitting circuit 11 and the wave receiving circuit 12 are connected to the same electrode arrangement. Note that the switch scanning circuits 14a and 14b as described above are, for example,
For each electrode in electrode array A or B, transmitter circuit 11.
Delivery circuit 12. The receiver is realized by providing a plurality of arrays of 1×3 channel multiplexer circuits that enable connection with each circuit of the bias voltage application circuit 13, and a matrix switch that enables electronic scanning using an electrode array. A signal processing circuit unit is further connected to the wave circuit 12, and image pickup is performed by performing signal processing compatible with various electronic scanning methods.

In this electronic scanning type ultrasonic imaging device, when transmitting or receiving waves, electronic focusing of the ultrasound is performed with at least one of the electrode arrangement directions set as the azimuth direction of the tomographic plane on which the Wk image is performed. 11 and receiving circuit 1
Since the dividing direction of the electrode array A or B connected to the pole array A or B determines the orientation direction of the obtained tomographic plane, the circuits connected to the pole array A or B are alternated by the switch scanning circuits 14a and 14b. By W! The two tomographic planes to be imaged are formed so that their azimuths are at an angle made by the arrangement directions of electrode arrays A and B, that is, perpendicular to each other. 6 When the electron scanning method is sector scanning, as shown in Fig. 3 ( a) PI
, P2, fan-shaped orthogonal pie-lane imaging is realized.

In such imaging, piezoelectricity is applied to the electrostrictive vibrator 2 in the following manner. Now, bias voltage application circuit 1 is applied to electrode arrangement A of electrostrictive vibrator 2 shown in FIG. 2(a).
3 is connected by switch scanning circuit 14a, and for electrode arrangement B, transmitting circuit 1 is connected by switch scanning circuit +4b.
As shown in FIG. 1 (b), the electrode Ai of the 1i-pole array A is selected to apply a bias voltage, and the other electrodes are grounded. It is also assumed that electrode Bj is selected from electrode array B and the wave transmitting circuit 11 and wave receiving circuit 12 are in a connected state. At this time, a bias electric field is applied to the portion of the electrostrictive vibrator sandwiched between the electrode A1 and the facing electrode array B, and piezoelectricity is induced. At this time, 1! Switch scanning circuit +4b on pole Bj
When a transmission signal voltage is applied through the oscillator, the bias voltage and signal voltage are simultaneously applied to the hatched area in Fig. 2(b), so due to the properties of the electrostrictive material, it cannot be driven as a vibrator. and emits ultrasonic waves. Furthermore, when ultrasonic waves are received in this connected state, a reception voltage is generated at the electrode Bj, and the reception voltage is also transmitted to the reception circuit 12 via the switch scanning circuit +4b.
becomes the input signal. When the electronic scanning method for imaging is a sector-type electronic scanning method and ultrasonic transmission and reception is performed using a phased array method, a bias voltage is applied to all the electrodes of the electrode array A, and the entire surface of the electrostrictive vibrator 2 becomes piezoelectric. It becomes sex. It goes without saying that the selection operation of these electrodes can be similarly performed by alternating the connections between the switch scanning circuits 14a, 14b and other circuits.

FIG. 3 shown above is a conceptual diagram showing the relationship between pie-lane imaging and three-dimensional imaging. FIG. 3(a) shows the positional relationship between the imaging regions of two sector-shaped B-mode tomograms (pie lanes) PI and P2 that are perpendicular to each other and the region of interest inside the subject, using the ultrasound probe T. It is shown along with the location. The tip surface of the ultrasonic probe T is parallel to the main surface of the electrostrictive vibrator 2.

When the electrode array A of the electrostrictive vibrator is used for electronic focusing of transmitting or receiving waves, a semicircular B-mode tomographic image P1
is obtained, the switch scanning circuits 14a and 14b cause the wave transmitting circuits 11. By changing the connection between the wave receiving circuit 12 and the electrode array A to the electrode array B, the imaging plane
It is changed from Pl to P2. B-mode tomographic plane PI, P2
The images are taken alternately, and the two tomographic planes are alternately displayed on the display of the ultrasound imaging device at high speed (this is called "contingency").
By displaying the region of interest 0 in the subject in the vicinity of the center of both tomographic images, the size of the region of interest ○ can be estimated, the positional relationship, etc. can be easily determined.

When this ultrasonic imaging device is a medical ultrasonic introductory device, the region of interest ◯ corresponds to an organ or an affected part of the human body. By such pie-lane imaging, three-dimensional positional relationships can be easily grasped in a pseudo manner. Furthermore, as shown in FIG. 3(b), when scanning the B-mode tomographic image PI or P2 in a direction orthogonal to the plane to perform three-dimensional imaging over the entire region V inside the subject, the above-mentioned method is applied. Through such an operation, it is possible to optimally position the probe using pie-lane imaging in advance, and then to start capturing the entire three-dimensional image.

When imaging the entire region V mentioned above with high resolution, the number of times ultrasound is transmitted and received increases dramatically compared to when imaging a conventional B-mode tomographic image, so the imaging time becomes longer. The real-time nature of diagnostic images is significantly reduced. Therefore, as mentioned above, using pie-lane imaging, which requires about twice the imaging time as conventional methods, the probe is positioned so that the center position of the entire area V is at the optimal position, and then three-dimensional imaging is performed. If this is done, imaging can be performed extremely efficiently.

Furthermore, with the above-described device configuration, it is possible to select between imaging performed by scanning the tomographic plane PI and imaging performed by scanning the tomographic plane P2. Fault plane PI.

Since the resolution in the azimuth direction of P2 and the resolution in the thickness direction of the surface generally do not match, the switch scanning circuit 14
The configuration of the present invention, in which the connections of a and +4b can be alternated, allows the electron scanning direction, which increases the resolution of the imaging area, to be set to P of the tomographic plane.
It is possible to select which direction to set, I or P2, without rotating the position of the probe. A switch is provided on the ultrasound probe, the imaging device body, or an extension of the body so that the operator can easily switch between pie-brane imaging and 3D imaging and select the scanning direction for 3D imaging. It is configured so that it can be changed using the trigger input of the switch.

FIG. 4 is a block diagram showing a specific example of the configuration of the ultrasonic imaging device according to the present invention. Electrode arrangement A1 of electrostrictive vibrator 2
~An is the electrode arrangement B, ~B in the switch scanning circuit 14a.
n is a switch scanning circuit! 4b. Transmission circuit 1
1. Delivery circuit 12. The bias voltage application circuit I3 is connected to both switch scanning circuits 14 a and +4 b. Transmission circuit 11. Delivery circuit! 2 is a signal line group corresponding to the number of channels used simultaneously in linear scanning, sector scanning, etc. by electronic focusing, and is a switch scanning circuit +
4a and +4b.

In the case of a linear electronic scanning system, the switch scanning circuits +4a and 14b are the transmitting circuit II, the receiving circuit! It has the function of connecting a series of signal line groups from 2 to the same number of electrode groups in A, ~An, or B1 to Bn, and sequentially moving and scanning them. Output of bias voltage application circuit 13 and electrodes A1 to A
n or B1 to Bn, for example, the wave transmitting circuit +1. When the wave receiving circuit 12 is connected to the electrode array A, it is connected to part or all of the electrode array B, and is always connected to the wave transmitting circuit 11. This is performed for the electrode arrangement on the facing side accompanying the connection operation of the transfer circuit 12. A signal processing circuit 41 is connected to the wave receiving circuit 12 and converts the signal into a signal for displaying the image price. The converted signal is displayed by the image display section 42,
It is displayed to the measurer as a B-mode tomographic image, pie-lane tomographic image, C-mode tomographic image, three-dimensional image, etc.

These series of imaging operations are controlled by the control circuit 43. The control circuit 43 performs a switching operation between a pie-brain tomographic image and a three-dimensional image in response to a trigger input from a switch 44 provided on the ultrasound probe, the imaging device main body, or an extension thereof.
Alternatively, an operation of switching the scanning direction of the three-dimensional image is performed.

Hereinafter, imaging by aperture synthesis will be specifically described as an imaging method according to the present invention.

FIG. 5(a) is a conceptual diagram for explaining the imaging operation by aperture synthesis. First, in the configuration of this embodiment,
The strip-shaped electrode array A provided on the upper main surface of the electrostrictive vibrator 2 and the electrode array B provided on the lower main surface are used to connect the switch scanning circuits 14a and 14b to other circuits. For alternating imaging operations, the shapes are configured equivalently.

In FIG. 5(a), the bias voltage application circuit 13 and the electrode array A are connected to the transmitter circuit 11. Indicates that the transfer circuit 12 and the electrode array B are in a connected state. To the polar array Each electrode is connected to the bias voltage application circuit 13 or grounded by the switch scanning circuit 14a. Further, a part of the electrode array B is connected to the wave transmitting circuit 11 and the wave receiving circuit 12 by another switch scanning circuit +4b.

Here, the wave transmitting circuit 11 includes an excitation pulse generation circuit 11a and a delay circuit 11b. The delay circuit 11b realizes electronic focusing by generating a group of transmission pulse signals with different delay times based on the transmission pulses generated by the excitation pulse generation circuit 11a, so that the ultrasonic pulses are delivered to a desired region within the subject. Excite the oscillator so that it converges. Further, at this time, the output of the wave transmitting circuit II is insulated so that it does not become an input to the wave receiving circuit 12.

When receiving ultrasonic echoes, the transmitter circuit +1 is insulated,
The reception signal voltage from the vibrator is amplified by the delivery circuit 12. The amplified signal group is transmitted to a signal processing unit that performs phasing and summation (electronic focusing during delivery) so that it becomes a received signal of an echo from a desired region within the subject. Excitation pulse generation circuit 11a.

The connection relationship between the delay circuit 11b and the wave receiving circuit 12 is not limited to the illustrated configuration.
A configuration may also be adopted in which several JE channels are connected to each terminal of the switch scanning circuit +4b, and each excitation pulse generation circuit outputs a transmission pulse signal by a trigger input having a different delay time for electronic focusing.

Under such a configuration, at the time when scanning of the ultrasound beam is started, the bias voltage application circuit I3 is connected to the endmost part 1iai A selected from the electrode array A by the switch scanning circuit 14a, A bias electric field is applied between the opposing electrode array B.

The other electrodes of the electrode array A that were not selected are grounded. In the diagram, the intersections indicated by black circles in the matrices of the switch scanning circuit +4a are in a connected state. Also, at the same time, switch scanning circuit! Among the matrix switch sections 4b, a series of intersections indicated by white circles are connected.

In this state, switch scanning circuit! The intersection of the vibrator sandwiched between the electrode A1 selected in step 4a and the series of electrodes of electrode arrangement B selected in switch scanning circuit 14b is
The output of the excitation pulse generation circuit 11a, which is induced by the bias electric field and becomes piezoelectric and functions as an electro-acoustic FF converter, becomes a series of signals having different delay times by the delay circuit 11b. It is connected to a selected series of electrodes in the electrode array B via the switch scanning circuit 14b.

At this time, the delay circuit 11b is the switch scanning circuit +4b
For a series of electrodes partially selected from the 1i-pole array B, the longest delay time is given to the signal output to the electrode at the center of the series, and the shortest delay is given to the electrodes at both ends. By giving time, electronic focusing is performed so that the wavefront of the ultrasonic pulse generated by excitation of the vibrator corresponding to each electrode is formed in an arc shape.The wavefront of the ultrasonic pulse emitted at this time is The shape of the electrode A, viewed from the X-axis direction in the figure, within a plane parallel to the longitudinal direction, is an arc whose radius is a certain focal length determined by the distribution of delay times of the transmitted pulse group.

In addition, since the width of each strip-shaped electrode in electrode array A in the dividing direction (X-axis direction) is sufficiently narrow compared to the length direction, and the directivity of the vibrator is close to omnidirectional, The shape of the sound wave beam becomes fan-shaped. Therefore, when viewed from the y-axis direction, the convergence region of the ultrasonic beam due to electronic focusing in this case exists near a circular arc whose radius is the focal length determined by the conditions of the delay circuit 11b. After transmitting the ultrasonic pulse in this way, when receiving an echo from inside the object, only the piezoelectrically induced portion of the vibrator causes voltage fluctuation due to excitation, and the received wave passes through the switch scanning circuit +4b. A group of received signals is input to the circuit 12 .

At this time, the signal processing circuit connected subsequent to the wave receiving circuit 12 is located on an arc a whose radius is a certain focal length viewed from the y-axis direction, in a process opposite to the electronic focusing during wave transmission. The received signal values are added by assuming a delay time distribution for the received signal group sequentially so that the sum of the signals from the reflection sources is the sum of the signals from the reflection sources. That is, the delay time distribution is sequentially assumed in correspondence with the focal length from the shallowest part to the deepest part of the imaging region, and the phasing and addition process is performed.

Furthermore, on the storage circuit connected subsequent to the signal processing circuit,
A two-dimensional storage space sufficient to hold all the signal values necessary for imaging at least one tomographic plane is provided corresponding to the space in the actual subject, and the signal processing circuit outputs it by phasing and addition processing. The signal values are added and held as signal values at points on a circular arc whose radius is the focal length determined by the delay time distribution at that time. This series of ultrasonic transmission/reception and addition/holding operations of the phased addition value of the received signal group in the storage space is repeated every time the switch scanning circuit 14a sequentially moves the electrode to which the bias voltage is applied.

As shown in FIG. 5(a), when there is a reflection source C inside the subject, when the distribution of delay times corresponding to the arc a is given by the phasing and addition process, the reflection source in the corresponding storage space A large value is added and held to a group of points on the arc that includes C. The switch scanning circuit 14a sequentially switches the electrodes selected from the electrode array A, and even when electrode A is selected, a distribution of delay times corresponding to a circular arc including the reflection source C is assumed in the phasing and addition process. Then, a large value is added and held on the arc in the corresponding storage space. At this time, the point corresponding to the reflection source C in the storage space is the intersection of the arcs a and b, and the value added and held at the corresponding point in the storage space increases greatly. By repeating this operation for all the electrodes in the am array A, the integrated values of the phasing addition values developed in the storage space are reinforced at the position corresponding to the reflection source C.

As a result of the increase in the integrated value due to such sequential addition for all the reflection sources in the imaging region within the subject, one piece of tomographic image information is formed in the storage space. Furthermore, the electrodes selected from electrode array A during transfer and connected to the bias application circuit do not need to be the same as the electrodes selected during wave transmission; other electrodes may also apply bias during transfer for the same wave transmission condition. The circuit may be connected to perform a receiving operation, and the operation may be repeated for all other electrodes of electrode array A one after another.

When imaging a three-dimensional area, the switch scanning circuit +4b repeats scanning to obtain one tomographic image by switching and moving the selected electrode groups at the same time using the aperture synthesis method. By opening a group of connections indicated by white circles and connecting a group of intersections indicated by black circles among the intersection points of the matrix portion of +4b, the selected portion of electrode array B is moved by one position in the scanning direction. .

By this operation, the position of the tomographic plane obtained by the above-described aperture synthesis method is moved in parallel in the arrangement direction of the electrode array B, that is, in the y-axis direction, in units of the division width of the electrode array B.

Furthermore, the storage space provided on the storage circuit is 3, which is sufficient to hold the signal values of the number of tomographic planes to be scanned and imaged in the y-axis direction.
It is necessary to secure dimensional storage space. In an actual imaging device, the number of electrode divisions is sufficiently larger than the number shown in FIG. 5(a), and three-dimensional imaging is performed by repeating this operation many times to scan successive tomographic planes. In the case of pi-brane imaging, the electrode group selection by the switch scanning circuit +4b is performed by selecting a group of electrodes at the center of the electrode array B and the transmitting circuit 11. After connecting the wave receiving circuit 12 and imaging one tomographic plane, switch scanning circuits 14a and +4
By alternating connections between b and other circuits, imaging of tomographic planes in the orthogonal direction is performed.

FIG. 5(b) shows the switch scanning circuit 14a of this embodiment,
14b is composed of a matrix switch section 51 for electronic scanning and a multiplexer section S2. The matrix switch section 51 includes an electrode connection terminal group 51. .about.51n and the multiplexer portion 52 are opened and closed at the intersections of the matrices. In the switch scanning circuit 14a, the 1i-pole connection terminal groups 51, to 51n are connected to each of the electrodes A1 to An of the electrode array A, and in the switch scanning circuit 14b, they are connected to each of the electrodes B1 to Bn of the electrode array B.

The multiplexer part 52 is the matrix switch part 51
A 1×4 channel multiplexer 52, to 52n is connected to each row-direction signal line. Here, each terminal of the multiplexers 52, to 52n is connected to a wave transmitting circuit 1.
1. Delivery circuit 12. A bias voltage application circuit 13 and a connection terminal to a ground point are provided.

These switches are opened and closed according to the operations during wave transmission and delivery.

FIG. 6 is a diagram showing the relationship between the electronic focus and the tomographic scanning direction based on phasing and addition of signal groups during wave reception. Figure 6 (
5(a) is a side view of the vibrator viewed from the X-axis direction in the connected state shown in FIG. 5(a), and FIG. 5(b) is a side view of the vibrator viewed from the Ry-axis direction. Electrode arrangement A shown in FIG. 6(b)
A DC bias voltage is applied to electrode A, and the other bias electrodes are grounded. In addition, in FIG. 6(a), for some electrodes 85 to B of the electrode array B, the wave transmitting circuit 11 and the wave receiving circuit 12 of FIG. 5(a) are connected to the switch scanning circuit +4
connected by b.

The electrostrictive vibrator 2 is vibrated by applying excitation pulse voltages with different delay times to the electrodes 81 to B so that the ultrasonic pulses converge on a certain circular arc region within the subject. After transmitting an ultrasound pulse into the subject, the delivery circuit 12 amplifies the received echo signal, and the signal processing section then performs phasing and addition processing, that is, electronic focusing.

The broken line in FIG. 6(a) indicates that due to the above-mentioned electronic focus,
The movement of the vibrator from a near focal point R1 inside the subject to a far focal point R is shown in a plane perpendicular to the main surface of the vibrator and along the length direction of the electrode A. This is what is shown. As a result, 1! perpendicular to the main surface of the vibrator! Aperture synthesis processing of the tomographic plane H1 along the length direction of the polar array B is performed. In addition, the thick white arrow indicates that since three-dimensional imaging is performed by repeatedly imaging the tomographic plane, the connection area of the switch scanning circuit +4b moves, and accordingly, the position of the tomographic plane to be imaged also changes.
It shows how it moves in parallel to Hk via H, on the way.

FIG. 6(b) shows imaging of the tomographic plane H1 by aperture synthesis processing, viewed from the arrangement direction of the electrode arrangement B. Since the width of the electrodes in the electrode array A is small, the convergence of the electronic focus is nearly non-directional in this plane, and the convergence of the electronic focus is almost non-directional in this plane, as shown in R and
,R,,R, has an arc shape centered on the electrode A.

The electrodes to which the bias voltage is applied are A,,A,,A,,”・
, Al, . . . tAn, one tomographic image is obtained by aperture synthesis in which the received signal intensities are expanded and added in the storage space and held, and as shown in FIG. 6(a), the electrode array B is The electrodes to be simultaneously selected from are B and -Bi. ,,
By sequentially switching and moving as B, Y3 to B i+vyB, □ to B, +@, . . . , a plurality of tomographic images are scanned and three-dimensional imaging is performed.

In the 6th rgj (b), when the width of the ii pole A1 is small, the directivity approaches omnidirectionality, so the convergence area of the ultrasonic pulse becomes an arc, but when the width of the electrode is small, When the same excitation pulse voltage is applied, the radiation intensity of the ultrasonic wave decreases, which causes a practical problem when imaging a subject with large attenuation. Therefore, a method can be considered in which a bias voltage is simultaneously applied to a plurality of electrodes in the electrode array A to increase the IR intensity of the ultrasonic wave. In this case, the shape of the convergence zone of the ultrasonic pulse in the 6th CW (b) becomes so directional that it cannot be approximated by a circular arc. By developing and adding and retaining in the storage space, aperture synthesis of tomographic images can be performed in the same way.

The three-dimensional imaging area within the subject obtained by such scanning is rectangular when viewed from the direction of Figure 6(a), but the area viewed from the direction of Figure 6(b) is not shaped by aperture synthesis. Depending on whether the received signal is spread over the storage space, the area can be a rectangular area or a fan-shaped area. Note that the number of electrodes that perform transmission or reception simultaneously and the number of electrodes that simultaneously apply DC bias voltage are arbitrary (not limited to this embodiment).

Furthermore, when performing aperture synthesis of one tomographic image, the order in which electrodes to which bias voltages are applied may be selected, and in the case where multiple tomographic images are scanned, the order in which each tomographic image is scanned may be in any order. In addition, in the connection state of the electrodes and the circuit shown in FIG. 6(b), the number of electrodes selected from electrode array B at the same time is sequentially changed during transmission and reception of ultrasonic waves to change the aperture of the vibrating part, so that the focus is on the vibrator. It is also possible to improve the resolution by setting a small aperture for reception from a part close to the surface of the plane and a large aperture for reception from a far part.

The ultrasonic scanning means in the electrode arrangement direction in FIGS. 5(a) and 6(a) corresponds to linear electronic scanning in a conventional electronic scanning imaging device. On the other hand, it is also possible to use the ultrasonic scanning means in the electrode arrangement direction as equivalent to sector-type electronic scanning.

0M7 (a) is the same as FIG. 6, which shows the case where imaging is performed by making the ultrasonic scanning in the arrangement direction of the electrode array B in FIG. 6(a) correspond to sector-type electronic scanning. 5(b) is a side view of the connection state shown in FIG. 5(a) viewed from the X-axis direction.
is a side view seen from the same y-axis direction. As in the case of the linear similar scan in FIG. 6, electrode A of the electrode array A shown in FIG. 7(b).

A DC bias voltage is applied to the electrode, and the other electrodes are grounded. In FIG. 7(a), all electrodes B of electrode arrangement B
, ~Bn has a transmitting circuit +1. A wave receiving circuit 12 is connected.

In this connected state, a group of excitation pulse signals with a delay time distribution are generated for the electrodes B1 to Bn so that the ultrasonic pulses converge on a circular arc region in a plane parallel to the electrode arrangement B. is added and transmitted. The delay time distribution at this time is
This is similar to the phased array method in sector type scanning.

The delivery circuit 12 amplifies the echo signal, and then the phasing and addition section performs electronic focusing. The broken line in FIG. 7 (8) shows the length of the electrode A as it moves from a focal point S close to the vibrator to a focal point S far away by phased array electronic focusing during reception. The figure is shown in a plane parallel to the transducer direction and perpendicular to the main surface of the vibrator. This shows how aperture synthesis is performed on the tomographic plane G1 parallel to the length direction of the electrode array B, and how multiple tomographic planes are scanned in the direction of the arrows G, GJ to Gk for three-dimensional scanning. Show the situation.

Moreover, FIG. 7(b) shows the convergence region s,' on the fault plane G,
, s,', s,' as seen from the arrangement direction of electrode array B. Since the width of the electrodes in electrode array A is small, the directivity at fault plane G, is close to omnidirectional, and s,',
Since s, , S, ' are arcuate with the electrode Ai at the center, one tomographic image can be obtained by aperture synthesis similar to the case in FIG. 6. In addition, even with a method of increasing the radiation intensity of ultrasound by simultaneously applying bias voltage to multiple electrodes in the t-pole array A, it is possible to expand and integrate the received signals in the storage space while taking into account the directivity function. This allows aperture synthesis of similar tomographic images.

The electrodes to which the bias voltage is applied are A, , A, , A,.

By sequentially moving from 2A, . By changing the delay time distribution of the phased array method as shown by the arrows in Figure 7(a), if the angle is sequentially changed, multiple tomographic images can be scanned and three-dimensional imaging can be performed. be exposed. In this case, the area inside the subject that is imaged is
When viewed from the direction of Figure 7 (a), it looks like a fan, but in the same direction (b)
The area viewed from the direction can also be fan-shaped.

Note that even in this sector-like scanning, the number of signal electrodes that perform transmission or reception at the same time and the number of bias electrodes that simultaneously apply DC bias voltage are not limited to the case of this embodiment, and are arbitrary. In addition, the order in which electrodes to which bias voltages are applied are selected by the switch scanning circuit for aperture synthesis of one tomographic image, and the delay time distribution in Figure 7 (a) given when multiple tomographic planes are scanned are also discussed. The setting order is
Needless to say, it can be anything.

8th [1! I is a diagram showing another example of the configuration of the ultrasonic imaging device according to the present invention. Electrode arrays A, ~A that intersect with each other
The electrostrictive vibrator 2 equipped with the transmitter circuit 11, the transfer circuit +2 . A bias voltage application circuit 13 is connected.

A wave transmitting circuit 11 and a wave receiving circuit 12 are connected to one of the electrode arrays A and B, and a bias voltage applying circuit 13 is connected to the other. In the case of pie-brain imaging, the control circuit 43
Accordingly, the imaging operation is performed by alternating the connections between the switch scanning circuits 14a and 14b and each circuit.

Now, it is assumed that the wave transmitting circuit 11 and the wave receiving circuit 12 are connected to the electrode array B by the switch scanning circuit 14b, and the bias voltage application circuit 13 is connected to the electrode array A by the switch scanning circuit 14a. Based on the logic signal output from the control circuit 43, the switch scanning circuit 14a selects an electrode to which a bias voltage is applied from the electrode arrays A to ArI, and induces piezoelectricity in the driving portion of the electrostrictive vibrator 2 by a bias electric field. . The excitation pulse generation circuit +1a generates a transmission pulse voltage and serves as an input to the delay circuit 11b. The delay time group of the delay circuit 11b is set by the logic signal of the control circuit 43. Further, the excitation pulse signal group having the delay time distribution is input to the switch scanning circuit +4b, and is applied to a series of electrodes selected by the logic signal of the control circuit 43 among the electrode arrays B, to Bn.

The echoes of the ultrasonic pulses thus transmitted.

It is received by the piezoelectric induction part of the electrostrictive vibrator and sent as a received signal to the transfer circuit 12 via the switch scanning circuit +4b.
becomes the input. The received signal group amplified by the wave receiving circuit 12 undergoes electronic focusing of the received wave by the phasing and addition circuit 81 to become a signal for aperture synthesis, is A/D converted, and is sequentially added to the storage space on the storage circuit 82.・It is expanded while being maintained. The control circuit 43 switches the connection with the electrode of the switch scanning circuit +4a on the bias voltage application side, repeats the ultrasonic transmission/reception operation and the expansion of the received signal value to the memory circuit 82, and performs the operation for all electrode arrays A1 to An. end the scan,
The 0 display circuit 83, which completes the aperture synthesis to obtain two tomographic images, converts the aperture synthesis value in the storage space held by the memory circuit 82 into a signal, converts it into a signal, and outputs the signal voltage to the display. and display the tomographic image.

In the case of pie-brane imaging, a series of electrodes in the center of the electrode array connected to the switch scanning circuit +4b or the entire electrode array is used to capture a tomographic plane perpendicular to the main surface of the electrostrictive vibrator 2 and located in the center. Imaging is performed, and the connection of the switch scanning circuits 14a and 14b is alternated by the logic signal output of the control circuit 43, and the same scanning is repeated again.
can be output on the display.

When performing three-dimensional imaging, first, in the case of scanning similar to a linear type, the control circuit 43 is a switch scanning circuit +4b.
, select a series of electrode groups that have moved one position from the time of the previous tomographic scan from electrode arrays B and ~B, and
Again, repeat aperture synthesis to obtain one tomographic image 3
In addition, in the case of sector-like scanning, @polar array 81~
Phased array electronic focusing is performed using all of B, and thereby a tomographic image with a different deflection angle from the main surface of the transducer than the previous tomographic plane scanning time is captured.

In this way, the aperture composite values of continuous tomographic planes are held in the storage space of the memory circuit 82, and the monitor display circuit 83 displays arbitrary tomographic planes and recombined three-dimensional stereoscopic images. At this time as well, by alternating the electrode arrays A and B in response to a logic signal from the control circuit 43, it is possible to select the imaging direction of the tomographic plane in directions orthogonal to each other. Switching between pie-brane imaging and three-dimensional imaging and switching of the traveling direction of three-dimensional imaging are performed by a trigger input to a changeover switch 44 provided on the ultrasound probe, the imaging apparatus main body, or an extension thereof.

In the above imaging, for example, the wave transmitting circuit +1 and the wave receiving circuit 12
While fixing the settings of the switch scanning circuit +4b on the side to which the bias voltage is applied,
A is scanned repeatedly to aperture synthesize one tomographic image, but conversely, while the switch scanning circuit 14a on the bias voltage application side is fixed, the switch scanning circuit +4b on the ultrasonic transmitting/receiving circuit side is It is also possible to perform electronic scanning and perform aperture synthesis of multiple tomographic planes simultaneously.

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to realize an ultrasonic imaging method in which tomographic images or three-dimensional image information inside a subject can be obtained by ultrasonic echography. By implementing an imaging device based on this imaging method, an examiner can easily and quickly estimate the three-dimensional structure and tissue inside a subject.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the configuration of a peripheral circuit connected to an electrostrictive vibrator, Figure 2 is a diagram explaining a crossed electrode type electrostrictive vibrator, and Figure 3 is a diagram explaining pipe lane imaging and three-dimensional imaging. A diagram explaining the relationship, FIG. 4 is a diagram explaining the configuration of the ultrasonic imaging device,
FIG. 5 is a diagram explaining the imaging method using aperture synthesis and the configuration and function of the circuit means connected to the transducer; FIG. 6 is a diagram explaining the aperture synthesis method in the case of electronic scanning similar to a linear type; FIG. FIG. 8 is a diagram illustrating an aperture synthesis method in the case of electronic scanning similar to a sector type, and FIG. 8 is a block diagram illustrating the configuration of an imaging apparatus using the aperture synthesis method. A, B: electrode array, 11: wave transmitting circuit, lla: excitation pulse generation circuit, llb: delay circuit, 12: wave receiving circuit, 13
: Bias voltage application circuit, 14a, +4b : Switch scanning circuit, 2:1! Strain oscillator, 21: oscillator selection part, PI, P2: B-mode tomographic plane, 0. region of interest, V: entire imaging region, T: distorted ultrasound probe, 41: signal processing circuit, 42: image display section, 43: control circuit, 44: changeover switch, R1 to R, , S, to s ,,s,'~S,':
Convergence area by electronic focus, 81: Phasing addition circuit,
82: Memory circuit, 83: Display circuit. Figure (a) (a) Figure (Part 1) Figure (Part 2) Figure (Part 2) Figure (Part 2) (b) Figure (Part 1) (a) Figure (at

Claims (1)

[Claims] 1. A plurality of strip-shaped electrode arrays A and B that are perpendicular to each other or intersect at a certain angle are provided on both main surfaces of a flat plate of electrostrictive material whose piezoelectricity is induced by a bias electric field. an ultrasonic probe that uses an ultrasonic probe as a transducer, a wave transmitting circuit, a wave receiving circuit connected to the ultrasonic probe, and a bias voltage application circuit for inducing piezoelectricity in the electrostrictive material. In the acoustic wave imaging device, a switch scanning circuit is added between each of the electrode arrays A and B and the wave transmitting circuit, the wave receiving circuit, and the bias voltage application circuit, and by changing the opening/closing state of the switch scanning circuit, ultrasonic An ultrasonic imaging system characterized in that electronic scanning for transmitting and receiving sound waves can be performed arbitrarily by either of the electrode arrays A and B. 2. The ultrasonic imaging method according to claim 1, wherein two B-mode tomographic planes that are perpendicular to each other or intersect at a certain angle can be imaged alternately by changing the opening/closing state of the switch scanning circuit. 3. A claim characterized in that imaging of a three-dimensional region can be performed in any scanning direction by repeatedly scanning one tomographic plane by moving or deflecting it in the arrangement direction of the electrode array A or B. The ultrasonic imaging method according to item 1. 4. In addition to the above-mentioned means, a switch for the operator to switch the scanning direction is provided on the ultrasound probe or imaging device body or an extension of the main body, and the operator can change the scanning direction with the changeover switch. The ultrasonic imaging system according to claim 3, characterized in that: 5. An imaging method that alternately images two tomographic planes that are perpendicular to each other or intersect at a certain angle, and 3. Repeated scanning by moving or deflecting the image of one tomographic plane in the arrangement direction of the electrode array A or B. The dimensional domain imaging method and
2. The ultrasonic imaging method according to claim 1, wherein an operator of the imaging device can select the method. 6. In addition to the above-mentioned means, a switch for the operator to change the imaging method is provided on the ultrasound probe or the imaging device body or an extension of the main body, and the operator can change the imaging method using the changeover switch. The ultrasonic imaging system according to claim 5, characterized in that: 7. The ultrasonic imaging method according to claim 1, wherein the imaging is performed by performing aperture synthesis processing of the received ultrasonic signals in the arrangement direction of the electrode array A or B.