JP2000325343A - Ultrasonic diagnostic apparatus and wave transmitter/ receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve highly accurate examination, while reducing the frequency of transmissions and receptions, by an ultrasonic diagnostic apparatus for processing a three-dimensional image. SOLUTION: The wave transmitter/receiver 10 is a sparse-array type ultrasonic probe. A thick transmission beam 12 whose cross-section is flat is formed and plural thin receiving beams 14 overlapping with the transmission beam re formed. The transmission beam 12 is luster-scanned in the direction of the array of the receiving beam array 50, so that the echo data are taken in the three-dimensional space. Since the transmission beam 12 is flat, the energy of ultrasonic waves can be concentrated. And as a one-dimensional receiving beam array can be formed by each transmission, the received signal process suitable for the existing B-mode image processing is possible. Oval transmission element area and receiving element area are set on the wave transmitting/ receiving surface of the wave transmitter/receiver 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus and a transducer, and more particularly, to two-dimensional scanning of a transmitting and receiving beam for forming a three-dimensional image.

[0002]

2. Description of the Related Art In order to form a three-dimensional ultrasonic image of a living body, it is necessary to capture echo data in a three-dimensional space. Therefore, an ultrasonic probe for capturing three-dimensional echo data that mechanically scans an electronic scanning type one-dimensional array transducer has been put to practical use. However, in the case of such an ultrasonic probe, since a mechanical scanning mechanism needs to be housed inside, there is a problem that the probe shape becomes large.

[0003] Also, three-dimensional echo data can be taken in using a two-dimensional array transducer. The two-dimensional array vibrator has a large number of vibrating elements arranged two-dimensionally on a plane or a curved surface. In general, each vibrating element functions as a transmitting / receiving element.

However, since the two-dimensional array vibrator is composed of an extremely large number of vibrating elements, the structure is complicated and the production cost is high. In addition, the number of signal lines and the scale of the transmission / reception circuit are significantly increased. For this reason, there are many problems in realizing it.

Therefore, a sparse array vibrator has been proposed. If this array vibrator is briefly described, the array vibrator corresponds to a normal two-dimensional array vibrator obtained by thinning out a number of vibrating elements according to predetermined conditions. According to this sparse array vibrator, while maintaining the function of the two-dimensional array vibrator, the number of vibrating elements can be significantly reduced and the above-mentioned problems can be alleviated.
The technology development is expected.

By the way, in a sparse array transducer or a normal two-dimensional array transducer, if one reception beam is formed for one transmission beam in each direction in a three-dimensional space, all the reception beams are formed. A large number of transmissions and receptions are required before the echo data is captured. Therefore, it is conceivable to form a plurality of reception beams per transmission beam.

FIG. 7 conceptually shows a transmitter / receiver 110 and one transmission beam 114 and a plurality of reception beams 112 formed thereby. Reference numeral 113 denotes a beam central axis, and the transmission beam 114 has a form in which the cross section spreads in a circle around the center. In FIG. 7, the cross section of the transmission beam is shown as a rectangle for convenience.

[0008] The transducer 110 is a two-dimensional array of a plurality of ultrasonic elements. One thick transmit beam 11
For example, 4 × 4 (= 16) thin receive beams 1 per 4
A reception beam array 150 of 12 is formed, that is, for example, 16 reception signals can be obtained in one transmission. The receive beam array 150 is in an overlapping relationship with the transmit beam 114.

As shown in FIG. 8, a transmit beam is formed along the x direction and the y direction, and a receive beam array is formed each time. It is possible to capture three-dimensional echo data over the entire area. Note that reference numeral 200 indicates a virtual plane on which beam scanning is performed, and z indicates a vertical axis passing through the center thereof.

[0010]

However, if a thick transmission beam is simply formed, the ultrasonic energy is diffused accordingly. That is, there is a problem in that the ultrasonic energy per unit area becomes weak when viewed from the direction of the azimuth axis, which causes deterioration in image quality.

Further, when only a B-mode image of a desired cross section in a three-dimensional space is formed using the same ultrasonic probe (transducer), there is a problem that the above transmission / reception system is wasteful. . That is, in that case, for example, 4
Since only one reception beam train along the x direction or the y direction is used among the × 4 reception beams, there is a problem that transmission efficiency and reception efficiency deteriorate. In addition, existing ultrasonic diagnostic apparatuses (particularly digital scan converters) perform processing suitable for a one-dimensional received signal array obtained by scanning an ultrasonic beam in a one-dimensional direction. The problem is that it is difficult to adapt a two-dimensional received signal array.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to realize high-accuracy measurement in an ultrasonic diagnostic apparatus while reducing the number of times of transmission and reception.

Another object of the present invention is to provide an efficient transmission / reception system suitable for both three-dimensional image processing and tomographic image processing.

[0014]

(1) In order to achieve the above object, the present invention provides a transmitter / receiver having a plurality of transmitting elements and a plurality of receiving elements arranged in a predetermined pattern; Means for controlling the supply of a transmission signal to the transmission elements, wherein the transmission beam forming means forms a thick transmission beam having a flat cross section, and a phasing addition process is performed on the reception signals from the plurality of reception elements. Means to do
Receiving beam forming means for forming a receiving beam array comprising a plurality of narrow receiving beams arranged in the long axis direction of the flat cross section in a relationship overlapping with the transmitting beam.

According to the above configuration, a thick transmission beam having a flat cross section is formed, and a plurality of reception beams arranged in the long axis direction of the flat cross section are formed so as to overlap with the transmission beam. Preferably, the plurality of receiving beams form a one-dimensional receiving beam train.

According to the present invention, a plurality of received signals can be obtained per transmission, so that the total number of transmission / reception can be reduced. Further, since the transmission beam has a flat cross section, a beam having a simple circular cross section can be formed. The ultrasonic energy can be concentrated as compared with the above. That is, advantages of both reduction of transmission / reception time and improvement of image quality can be obtained.

In particular, since a received signal array arranged in the longitudinal direction can be acquired, for example, when a three-dimensional echo data acquisition probe combining the above-described electronic scanning and mechanical scanning is used. The received signal group can be acquired in the same arrangement as the obtained arrangement of the received signal groups. Therefore, various conventional image processing methods can be applied as they are, or even if the method needs to be changed, the changed contents are minimized. Can be stopped.

Preferably, the receiving beam forming means comprises:
It has a plurality of phasing addition sections provided for each reception beam. According to this configuration, it is possible to process received signals acquired in parallel and simultaneously.

Preferably, the transmitting beam forming means performs two-dimensional scanning of the transmitting beam, the receiving beam forming means forms a row of receiving beams for each transmitting beam, and obtains a plurality of rows obtained by the two-dimensional scanning. Image processing means for forming a three-dimensional image on the basis of the received signal. As the three-dimensional image processing method, various methods can be cited. For example, an image processing method based on a volume rendering method may be used. In this case, sequential image processing may be performed on the echo data along the ultrasonic beam.

Preferably, the transmission beam forming means performs a raster scan of the transmission beam in parallel with a longitudinal direction of the flat section. According to this configuration, the received signals can be acquired in the same order as in the case where the B-mode tomographic plane is scanned in parallel or oscillating.

Preferably, a plurality of transmitting elements are dispersedly arranged in a transmitting element area extending in a direction orthogonal to a long axis direction of the flat section on the transducer. Preferably,
On the transducer, a plurality of receiving elements are dispersedly arranged in a receiving element area extending from the center of the transmitting element area. Preferably, transmission elements and reception elements are densely arranged in an overlapping area of the transmission element area and the reception element area. Preferably, the plurality of transmission elements and the plurality of reception elements are transmission-only and reception-only elements, respectively.

(2) In order to achieve the above object, the present invention provides a transducer in which a plurality of transmitting elements and a plurality of receiving elements are arranged, wherein the plurality of transmitting elements are axes passing through an origin. And the plurality of receiving elements are dispersed in a receiving element area extending from the origin.

Preferably, the plurality of transmitting elements and the plurality of receiving elements are arranged in a pattern having no line symmetry.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the concept of the transmission / reception system according to the present invention. In FIG. 1, a transducer 10 is configured by arranging a plurality of transmitting elements and a plurality of receiving elements on a transmitting and receiving surface. Here, the arrangement pattern of the transmitting element and the receiving element will be described later with reference to FIGS.

The virtual plane 200 is a virtual plane for explaining the two-dimensional scanning of the ultrasonic beam, and is drawn as a plane parallel to the transmitting / receiving surface of the transmitter / receiver 10.

In the present embodiment, the transmitter / receiver 10 forms a thick transmission beam 12 having a flat cross section. In addition, a plurality of narrow receiving beams 14 are formed at the same time so as to overlap the transmitting beam 12. By the way, the formation of each ultrasonic beam can be easily realized by using a so-called electronic focusing technique. In this case, when forming a plurality of reception beams simultaneously, a plurality of reception circuits provided in parallel with each other as described later are used. Used.

In FIG. 1, for convenience, the transmission beam 12 has a fan beam shape, but in this embodiment, the cross section of the transmission beam 12 has a flat elliptical shape, which will be described later. 2 will be described.

In the present embodiment, for one transmission beam 12, a reception beam array 50 as, for example, eight one-dimensional reception beams included therein is formed, and in FIG. Receive beam array 50
Are formed. The transmission beam 12 is electronically scanned in the array direction of the reception beam array 50, that is, in the x direction,
When transmission / reception of one scan line along one x direction on the virtual plane 200 is completed, the scan line of the transmission beam 12 shifts by one step in the y direction, and the same transmission / reception as described above is performed, and this is repeated. That is, the transmission beam is raster-scanned on the virtual plane 200.

Therefore, the transmission beam 1 in the x direction
A B-mode tomographic plane can be formed by one scan of 2, and a plurality of B-mode tomographic planes can be formed in the y direction by the above-described raster scanning. That is, it is possible to form a three-dimensional echo data capturing space.

FIG. 2 is a conceptual diagram showing a cross section of a transmission beam and a reception beam. FIG. 2A shows FIG.
8 shows a beam cross section according to the transmission and reception system of the comparative example shown in FIG. 8, and FIG. 2B shows the concept of a beam cross section according to the transmission and reception system of the present embodiment.

In the comparative example, as shown in FIG.
A circular thick transmitting beam section 112A is formed, and, for example, 4 × 4 receiving beam sections 114A are set therein.

On the other hand, in the present embodiment, an elongated elliptical transmission beam cross section 1 which is flat along one direction is provided.
2A is formed, and a plurality of reception beam cross sections 14A are set while being included therein.

Incidentally, in FIG. 2, the direction perpendicular to the plane of the drawing coincides with the central axis (Z direction) of the transmission beam 12, where the X direction is the azimuth direction, which coincides with the x direction shown in FIG. ing. The Y direction is the elevation direction, and the projection of the Y direction on the virtual plane 200 is the y direction. The X and Y directions represent two axes orthogonal to the beam axis of the transmission beam.

As is apparent from the above description, according to the present embodiment, a plurality of received signals can be acquired per transmission, so that the number of transmission / reception times is smaller than when transmission / reception is performed once for each direction. It is possible to significantly reduce it. Also, as shown in the comparative example, the transmission power can be concentrated along one direction instead of spreading the transmission beam evenly, so that the problem of sensitivity deterioration due to dispersion of ultrasonic energy can be dealt with. It is. In addition, since the finally obtained reception signal array has the same arrangement as that of the conventional B-mode tomographic plane, the reception signal processing and image processing performed in the existing ultrasonic diagnostic apparatus are basically performed. This has the advantage that the method can be applied as is.

By the way, the transducer 10 shown in FIG.
It is constituted by an ultrasonic probe in which a plurality of vibrating elements are two-dimensionally arranged. Here, since the number of the vibrating elements constituting the transducer 10 is large, the transmission / reception processing becomes considerably complicated. Therefore, in the present embodiment, the above-described sparse type transducer 10 is used, and the arrangement pattern of the transmitting element and the receiving element according to the principle is shown in FIG. 3 in comparison with a comparative example.

In FIG. 3A, a transmitter / receiver area 110 and a receiver area 124 are set on a transmitting / receiving surface 120 of a transmitter / receiver 110 of the comparative example. The transmission element area 122 is a circular area having a small radius, and a plurality of transmission elements are dispersed and arranged inside the transmission element area 122.

The receiving element area 124 is the transmitting element area 1
It has a diameter larger than 22, in which a plurality of receiving elements are distributed. By the way, the transmitting element area 12
2 overlaps with the central part of the receiving element area 124.
The transmission beam 12 and the plurality of reception beams 14 as shown in FIG.
Is formed.

On the other hand, in the present embodiment, FIG.
As shown in (B), a transmission element area 22 and a reception element area 24 as shown are set on the transmission / reception plane 20 of the transmitter / receiver 10. Here, as understood from the comparison with FIG. 2B, the transmission element area 22 extends along the short axis direction orthogonal to the long axis of the flat transmission beam cross section, that is, the transmission beam cross section. Corresponds to the long axis direction of the transmission element area 22. In other words, the longitudinal direction of the cross section of the transmission beam and the transmission element area 2
2 coincides with the short axis direction. As is well known, when focusing an ultrasonic beam by electronic focusing technology,
It is desirable to set a wide aperture in a direction to enhance the convergence, and the above-mentioned elliptical cross relationship is set. Although the transmission element area 22 is set to be substantially elliptical in the present embodiment, various forms can be considered such as making the transmission element area 22 closer to a rectangular shape.

The elliptical receiving element area 24 shown in FIG. 3B has its major axis direction set along the array direction of the receiving beam array 50 shown in FIG. 1, that is, the X direction, and its x direction. The y-axis direction orthogonal to the above is the short-axis direction. On the y-axis direction, the receiving element area 24
Is set to be smaller than the length of the transmitting element area 22 in the major axis direction. Incidentally, as shown, the midpoints of both areas 22 and 24 coincide.

FIG. 4 shows an example of the arrangement of elements when the transducer shown in FIG. 2B is specifically realized. In FIG. Indicates a receiving element. Here, for example, each of the transmitting element and the receiving element is 48 elements, and in this case, each element is formed of a piezoelectric material, and the pitch thereof is 0.35 mm. As shown in the figure, the transmitting element and the receiving element are densely arranged in the overlapping part of the transmitting element area 22 and the receiving element area 24 shown in FIG. Are arranged separately.

In this embodiment, each of the vibrating elements is a receiving-only element and a transmitting-only element.
A part thereof may be used as an element for both transmission and reception.

In FIG. 4, according to the principle of the sparse scheme, both the transmission element pattern and the reception element pattern are asymmetric with respect to the horizontal axis and the vertical axis.
This is because side lobes are emphasized if there is symmetry.

Next, an ultrasonic diagnostic apparatus according to this embodiment to which the above-described transmission / reception method is applied will be described with reference to FIG. FIG. 5 is a block diagram showing the entire configuration. The transducer 10 is constituted by an ultrasonic probe inserted into a body surface or a body cavity, and the transducer 10 is constituted by a transmission element group 30 and a reception element group 32 as described above. Is done. Each element is disturbed on the wave transmitting / receiving surface as shown in FIG. 4, but in FIG. 5, they are separately shown for convenience.

The transmission circuit 34 is a circuit for supplying a transmission signal to the transmission element group 30. Specifically, the transmission circuit 34
By setting a predetermined delay time for each transmission signal output from the transmission circuit 34 under the control of No. 6, a desired transmission beam pattern can be formed in a desired direction. Here, the transmission beam 12 is raster-scanned on the virtual plane 200 as shown in FIG.

In the present embodiment, a plurality of receiving circuits 38 are provided by the number of receiving beams formed per transmission.
Are provided in parallel. That is, the receiving element group 32
The received signal array composed of a plurality of received signals output from the receiver is input to each of the receiving circuits 38 in parallel, and each receiving circuit 38 forms a receiving beam in charge. Specifically, each receiving circuit 38 is configured by a circuit that performs phasing addition of the received signal, and is configured by amplifiers and delay circuits provided in the same number as the received signal, an adder that combines the delayed received signal, and the like. You. of course,
It is also possible to form a plurality of reception beams as a result by switching and using one reception circuit in a time division manner.

The selector 40 is a circuit for selecting a reception signal after phasing and addition output from each reception circuit 38 and outputting it to the 3D memory 42. That is, the 3D memory 42
Stores the respective echo data acquired in the three-dimensional data acquisition space. The storage image is shown in FIG.
Is shown in

In FIG. 6, the 3D memory space 42A is
The scanning plane 202 is constituted by a plurality of scanning planes 202, and each scanning plane 202 is constituted by a plurality of receiving beam arrays 50. The receiving beam arrays 50 are aligned along the x direction. When the transmitting beams are scanned in the x direction, the receiving beam arrays 50 are formed by the number of the transmitting beams. Thereby, one scanning plane 202 is configured. When the scanning line of the transmission beam is shifted in the y direction according to the raster scanning, the scanning surface 202 is formed in the same manner as described above,
When a plurality of scanning planes 202 are finally formed, the capture of all echo data in the three-dimensional space is completed.

As can be understood from the above description, if the transmission beam is scanned only once in the x direction, for example, one scanning plane 202 similar to the conventional B-mode tomographic plane can be formed, and the B-mode tomographic plane can be formed as it is. Images and the like can be formed and displayed. Therefore, it is possible to maintain the conventional signal processing method as it is and further extend it to three-dimensional data processing. Such an image is being executed by the image processing unit 44 shown in FIG.
Is composed of a digital scan converter (DSC) and an image processing unit. The image processing unit 44 forms a desired tomographic image, a three-dimensional image, and the like.
In the three-dimensional image processing, various methods can be applied. Here, for example, it is possible to construct a three-dimensional image viewed from the viewpoint set by the viewpoint setting device 45. In that case, image processing based on a volume rendering method or the like may be applied. The ultrasonic image thus formed is displayed on the display unit 46.

[0049]

As described above, according to the present invention,
In the ultrasonic diagnostic apparatus, highly accurate measurement can be realized while reducing the number of times of transmission and reception. Further, according to the present invention, it is possible to realize an efficient transmission / reception method compatible with both three-dimensional image processing and tomographic image processing.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the concept of a transmission / reception system according to the present invention.

FIG. 2 is a conceptual diagram showing an ultrasonic beam cross section.

FIG. 3 is a conceptual diagram showing a transmitting element area and a receiving element area on a transmitting and receiving wave surface.

FIG. 4 is a diagram showing an arrangement pattern of a transmitting element and a receiving element in the transducer according to the present embodiment.

FIG. 5 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to the embodiment.

FIG. 6 is a conceptual diagram showing a data space in a 3D memory.

FIG. 7 is a conceptual diagram showing a transmission / reception method in a comparative example.

FIG. 8 is a conceptual diagram illustrating a transmission / reception method in a comparative example.

[Explanation of symbols]

10 transducers, 12 transmit beams, 14 receive beams, 50 receive beam arrays, 200 virtual planes.

Claims (10)

[Claims] 1. A transmitter / receiver having a plurality of transmission elements and a plurality of reception elements arranged in a predetermined pattern, and means for controlling supply of a transmission signal to the plurality of transmission elements, wherein Transmission beam forming means for forming a thick transmission beam, and means for performing phasing addition processing on reception signals from the plurality of reception elements, wherein the long axis of the flat cross section has a relationship overlapping with the transmission beam. And a receiving beam array forming means for forming a receiving beam array composed of a plurality of thin receiving beams arranged in a direction. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein said reception beam array forming means has a plurality of phasing addition sections provided for each reception beam. 3. The apparatus according to claim 1, wherein the transmitting beam forming means performs two-dimensional scanning of the transmitting beam, the receiving beam array forming means forms a receiving beam array for each transmitting beam, and the two-dimensional scanning. An ultrasonic diagnostic apparatus, comprising: an image processing unit that forms a three-dimensional image based on a plurality of reception signals acquired in accordance with (1). 4. An ultrasonic diagnostic apparatus according to claim 1, wherein said transmission beam forming means raster-scans the transmission beam in parallel with a longitudinal direction of said flat section. 5. The device according to claim 1, wherein a plurality of transmitting elements are dispersedly arranged in a transmitting element area extending in a direction orthogonal to a major axis direction of the flat cross section on the transducer. Ultrasound diagnostic device characterized by the following. 6. The ultrasonic diagnostic apparatus according to claim 5, wherein a plurality of receiving elements are dispersedly arranged in a receiving element area extending from a center of the transmitting element area on the transducer. apparatus. 7. The ultrasonic diagnostic apparatus according to claim 6, wherein transmitting elements and receiving elements are densely arranged in an overlapping area between the transmitting element area and the receiving element area. 8. The ultrasonic diagnostic apparatus according to claim 7, wherein the plurality of transmission elements and the plurality of reception elements are transmission-only and reception-only elements, respectively. 9. A transducer in which a plurality of transmitting elements and a plurality of receiving elements are arranged, wherein the plurality of transmitting elements are dispersedly arranged in a transmitting element area extending along a predetermined axis passing through an origin. The transmitter / receiver, wherein the plurality of receiving elements are dispersedly arranged in a receiving element area extending from an origin. 10. The transducer according to claim 9, wherein the plurality of transmitting elements and the plurality of receiving elements are arranged in a pattern having no line symmetry.