JP2004024464A - Ultrasonic search unit and ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a plurality of focal points in a direction of elevation orthogonal to an electronic scanning direction and to improve adhesiveness with a living body in this case. <P>SOLUTION: In an acoustic lens 12, a center portion 16 of a surface 15 has a shape projecting gently to a side of a living body, and a rear surface 20 of the acoustic lens 12 has a shape projecting gently to a side opposite to the side of the living body. When making ultrasonic waves pass through the center portion of the acoustic lens 12, a short distance focal point F1 can be formed. When making the ultrasonic waves pass through the whole of the acoustic lens 12, both of the short distance focal point F1 and a long distance focal point F2 can be formed. Each oscillation element constituting an ultrasonic oscillator 24 is divided into a plurality of elements 25a, 25b and 25c, which are made to operate selectively in order to switch over a transmission and reception port. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus, and more particularly, to forming a plurality of focal points (ultrasonic focus points).
[0002]
[Prior art]
The ultrasonic probe includes an ultrasonic vibrator (single vibrator or array vibrator), one or more matching layers provided on the upper surface thereof, an acoustic lens provided on the upper surface thereof, and an ultrasonic transducer. A backing layer provided on the lower surface side of the vibrator.
[0003]
Conventionally, acoustic waves passing through the acoustic lens are focused, thereby acoustically forming an ultrasonic beam. Specifically, in the case of the array transducer, the ultrasonic beam is focused by the electronic focus control in the electronic scanning direction, but the ultrasonic beam is basically focused by the acoustic lens in the elevation direction orthogonal thereto. You. Conventionally, such an acoustic lens has only one focal point. For example, the surface curvature of the acoustic lens is set such that the focal point is positioned at the center of the depth range to be observed. The back surface of the acoustic lens is formed flat, and the matching layer and the piezoelectric body also have a flat plate shape.
[0004]
As described above, if the focal point at one point is fixedly set in the elevation direction, there is a problem that the spatial resolution is inevitably reduced in the vicinity or deep portion of the ultrasonic probe. Therefore, it has been proposed to partially increase the curvature of the central portion of the curvature of the upper surface of the Kamaboko-shaped acoustic lens, that is, to impart two curvatures to the acoustic lens (Japanese Patent Laid-Open No. 6-245931). ).
[0005]
[Problems to be solved by the invention]
However, according to the above proposals, the center of the acoustic lens is raised and the end is more recessed from the living body side, so that the entire acoustic lens (particularly, the end) is in close contact with the surface of the living body. It will be difficult. On the other hand, in the related art, the shape of the lower surface side of the acoustic lens is flat, and the shape is not actively used.
[0006]
The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to make it possible to form a plurality of focal points with an acoustic lens while improving the adhesion to a living body as much as possible.
[0007]
It is another object of the present invention to be able to switch focus forming conditions.
[0008]
Another object of the present invention is to utilize the shape of the lower surface side or the shape of the vibrator of the acoustic lens.
[0009]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention provides a second shape in which a surface on the living body side has a first shape forming a first focal length, and a back surface on the non-living body side forms a second focal length. And a transmission / reception unit provided on the back side of the acoustic lens and having a shape along the second shape.
[0010]
According to the configuration, the front surface of the acoustic lens has a first shape for forming a first focal length, and the back surface of the acoustic lens has a second shape for forming a second focal length. In addition to the shape of the front surface, the shape of the back surface can also be used for ultrasonic beam formation. Here, the wave transmitting / receiving portion also has a shape along the back surface of the acoustic lens, and the shape of the back surface of the acoustic lens can be used for forming an ultrasonic beam together with the shape of the wave transmitting / receiving portion.
[0011]
Desirably, the first shape is formed in a first partial region in a region through which an ultrasonic wave passes, and is a convex shape toward the living body having a first curvature, and the second shape is a region through which an ultrasonic wave passes. It is formed over the entire area and has a concave shape toward the living body having the second curvature.
[0012]
According to the above configuration, an effect of converging the ultrasonic beam on both the front surface and the back surface of the acoustic lens can be exerted (provided that the acoustic velocity of the acoustic lens is lower than the acoustic velocity of the living body (1530 m / s)). is there). Since the first shape is formed in the partial region on the front surface and the second shape is formed on the entire back surface, the focus forming condition can be switched by selecting the operation range of the wave transmitting and receiving unit. For example, a single focal point can be formed by transmitting / receiving only at the center of the transmitting / receiving section, and a plurality of focal points can be formed by transmitting / receiving the entire transmitting / receiving section.
[0013]
Preferably, the first focal length is smaller than the second focal length. That is, the radius of curvature of the second shape is set to be larger than the radius of curvature of the first shape. As a result, the first focal length becomes a short distance, and the second focal length becomes a long distance.
[0014]
Preferably, the wave transmitting and receiving unit has an entire shape curved at the second curvature along the second shape. According to this configuration, the ultrasonic beam can be focused by the shape of the wave transmitting / receiving unit itself. That is, to be precise, an acoustic focusing effect can be exerted by the shape of the joint surface between the back surface of the acoustic lens and the upper surface of the wave transmitting / receiving unit.
[0015]
Preferably, a backing layer having an upper surface curved along the shape of the back surface of the wave transmitting / receiving section is provided. According to this configuration, unnecessary backside radiation from the wave transmitting and receiving unit can be effectively absorbed.
[0016]
Preferably, the wave transmitting / receiving unit includes a plurality of piezoelectric elements aligned in an electronic scanning direction, and the first shape and the second shape are curved in an elevation direction orthogonal to the electronic scanning direction.
[0017]
According to this configuration, the electronic focusing technique is applied in the electronic scanning direction as in the related art, while focusing can be performed in the elevation direction by using the shapes of the front and back surfaces of the acoustic lens.
[0018]
Preferably, each of the piezoelectric elements is constituted by a group of divided elements arranged in the elevation direction. According to this configuration, the focus condition can be switched by appropriately selecting the operation range in the elevation direction in the transmission / reception unit.
[0019]
(2) According to another aspect of the present invention, there is provided an ultrasonic diagnostic apparatus including an apparatus main body and an ultrasonic probe connected to the apparatus main body, wherein the ultrasonic probe has a surface on a living body side. A central portion has a first shape forming a near focal length, an acoustic lens having a second shape in which the entire back surface on the non-living body side forms a long focal length, and is provided on the back surface side of the acoustic lens, A vibrator having a shape along the second shape, wherein the vibrator is composed of a plurality of piezoelectric elements aligned in the electronic scanning direction, and each piezoelectric element is in an elevation direction orthogonal to the electronic scanning direction. The apparatus main body is composed of aligned divided element groups, and when the near-focus processing is formed, the central portion of the divided element group constituting each of the piezoelectric elements is transmitted and received by the transmitting and receiving operation to form a long focal length. Divided into the piezoelectric elements Characterized in that it comprises an opening control unit for operating transducing the entire pixel group.
[0020]
According to the above configuration, it is possible to control the transmission / reception aperture in the elevation direction, and when the transmission / reception is performed using only the central part in the divided element group constituting each piezoelectric element, the transmission / reception is performed there. Since the ultrasonic waves pass through the center of the acoustic lens, the propagation characteristics mainly according to the first shape of the center of the acoustic lens are formed. On the other hand, when transmitting and receiving is performed using the entire divided element group constituting each piezoelectric element, the ultrasonic waves transmitted and received there pass through the entire acoustic lens. And the second shape on the back surface of the acoustic lens forms a propagation characteristic. In the latter case, two focal points are formed.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a cross-sectional view illustrating a main configuration of an ultrasonic probe according to the present invention. Here, the sectional view shows an elevation direction orthogonal to the electronic scanning direction.
[0023]
In FIG. 1, the distal end cover section 10 is roughly composed of an acoustic lens 12 and a skirt section 14. The acoustic lens 12 is brought into contact with the surface of the living body and exerts an ultrasonic wave focusing action in the elevation direction. The skirt 14 is formed integrally with the end of the acoustic lens 12 and surrounds the side surface of the tip of the ultrasonic probe. Incidentally, the distal end cover portion 10 is entirely made of a material such as resin. Here, it is desirable to use, for example, a material having acoustic impedance equivalent to that of a living body.
[0024]
The acoustic lens 12 will be described. The surface 15 of the acoustic lens 12 is a surface that comes into contact with the surface of a living body, and the central portion 16 has a gentle convex shape. In the present embodiment, the curvature of the central portion 16 is the same in the electronic scanning direction, and has a cylindrical shape as a whole. Flat portions 18 are formed on both sides of the central portion 16. In this embodiment, the flat portion 18 forms a plane along the elevation direction (and the electronic scanning direction). Incidentally, the edge of the acoustic lens 12 is rounded.
[0025]
On the other hand, the back surface 20 of the acoustic lens 12 has a gentle convex shape toward the non-living body side. Here, the radius of curvature of the back surface 20 is larger than the radius of curvature of the central portion 16 of the front surface 15. Accordingly, the central portion 16 exerts an ultrasonic focusing effect having a focal point F1 at a short distance as indicated by reference numeral 100 in the figure, while the back surface 20 exerts an ultrasonic focusing effect of forming a focal point F2 at a long distance. Incidentally, as shown in FIG. 1, the bulge of the central portion 16 is not so large as the whole surface 15, and when the surface 15 is brought into contact with the living body surface, the whole surface 15 can be brought into close contact with the living body surface. . That is, if the flat portion 18 instead of the flat portion 18 has a form withdrawn into the non-living body side, the adhesion to the living body is reduced in the portion, but this embodiment solves such a problem. be able to.
[0026]
In the present embodiment, the focal length of the focal point F1 is, for example, 4 mm, and the focal length of the focal point F2 is, for example, 9 mm.
[0027]
The wave transmitting / receiving section 26 and the backing layer 27 are housed inside the front end cover section 10. Here, the wave transmitting / receiving section 26 is configured by the matching layer 22 and the ultrasonic vibrator 24 in the present embodiment, and the acoustic lens 12, the matching layer 22, and the ultrasonic vibrator 24 are respectively superposed. The matching layer 22 has a form that has a gently convex shape toward the non-living body side, and similarly, the ultrasonic transducer 24 also has a form that has a gently convex shape toward the non-living body side. . The curvature of each member matches the curvature of the back surface 20 of the acoustic lens 12. The surface on the non-living body side of the ultrasonic transducer 24 is joined to the upper surface of the backing layer 27, and the upper surface of the backing layer 27 has a gentle concave surface on the living body side. Incidentally, the curvature of each member is the same at each position in the electronic scanning direction.
[0028]
The ultrasonic transducer 24 constitutes an array transducer composed of a plurality of transducers. FIG. 2 conceptually shows the configuration of the ultrasonic vibrator 24. The ultrasonic vibrator 24 includes a plurality of vibrating elements 25 arranged in the electronic scanning direction. Are composed of the elements 25a, 25b, 25c.
[0029]
As shown in FIG. 1, the element 25a at the center has a size corresponding to the range of the center 16 of the acoustic lens 12 in the elevation direction, and the elements 25b and 25c at both ends of each vibrating element 25 are flat. It has a size corresponding to the size of the portion 18. In the present embodiment, each vibration element 25 is constituted by three elements 25a, 25b and 25c, but may be constituted by more elements.
[0030]
As described above, since each vibration element 25 is divided into a plurality of elements in the elevation direction, there is an advantage that the transmission and reception aperture in the elevation direction can be switched as described later.
[0031]
Incidentally, the matching layer 22 is constituted by a plurality of matching elements arranged in the electronic scanning direction. Here, each matching element corresponds to each vibration element 25. Each matching element is divided into three elements 23a, 23b, and 23c as shown in FIG. 1, and the respective elements 23a, 23b, and 23c are superposed with a size corresponding to the elements 25a, 25b, and 25c. ing. Incidentally, as shown in FIG. 1, the boundaries between the elements 25a, 25b, 25c and 23a, 23b, 23c are formed in parallel with the direction orthogonal to the elevation direction and the electronic scanning direction in the figure. However, it is also possible to form the boundary obliquely toward the direction of the focus point. As described above, since each of the vibration elements and each of the matching elements are divided into a plurality of elements, it is possible to effectively solve the problem of the ultrasonic wave wraparound or crosstalk in the elevation direction. Of course, as long as such a problem does not occur, each matching element can be made of a single material.
[0032]
Further, in the embodiment shown in FIG. 1, each vibration element 25 is divided into a plurality of elements, but each vibration element 25 may be configured as a single element. In this case, two focal points can be formed when transmitting and receiving ultrasonic waves using the respective vibration elements.
[0033]
FIG. 2 is a conceptual diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to the present embodiment. This ultrasonic diagnostic apparatus is roughly composed of an ultrasonic probe 30 and an apparatus main body 32.
[0034]
Describing the apparatus main body 32, the transmission unit 34 is a circuit that supplies a transmission signal to the elements 25a, 25b, and 25c that constitute each of the vibration elements 25, and forms a transmission beam in the electronic scanning direction. It has a function of switching the transmission / reception aperture in the elevation direction. Of course, electronic beam forming control may be performed in the elevation direction instead of or together with the transmission / reception aperture control.
[0035]
The receiving unit 36 has a function of receiving a received signal from an element constituting each of the vibration elements 25, executing a phasing addition process, and thereby forming a received beam. Similarly to the transmitting unit 34, the receiving unit 36 executes the electronic scanning control of the received beam in the electronic scanning direction, and executes the switching control of the transmission / reception aperture in the elevation direction. Of course, in this case, control regarding reception beam forming may be performed in the elevation direction. The control unit 38 is means for switching the operating conditions of the transmitting unit 34 and the receiving unit 36. The input unit 40 is configured by an operation panel or the like, and can switch a focus forming condition or a beam forming condition by a user. Of course, such switching of the conditions may be automatically performed according to the transmission / reception mode or the diagnosis depth.
[0036]
The image processing unit 42 is a circuit that forms an ultrasonic image such as a B-mode image (two-dimensional tomographic image) based on the reception signal after the phasing addition output from the receiving unit 36. The display unit 44 displays such an ultrasonic image.
[0037]
When the ultrasonic probe 30 is brought into contact with the surface of a living body and an ultrasonic diagnosis is performed on a region near the body surface in that state, the vibration of each vibration is controlled by the operation of the transmission unit 34 and the reception unit 36 under the control of the control unit 38. Only the element 25a in the central part of the element 25 performs the wave transmitting / receiving operation. Then, the ultrasonic wave passes through only the central portion of the acoustic lens 12, and in this case, the ultrasonic focusing action of the central portion 16 on the surface 15 becomes dominant. That is, the focus F1 at a short distance is set. On the other hand, when performing an ultrasonic diagnosis over a deep part from the body surface or from a short distance to a long distance, all elements in each of the vibration elements 25 transmit and receive by the action of the transmission unit 34 and the reception unit 36, and the As a result, the ultrasonic wave passes through the entire acoustic lens 12. Therefore, the focal point F1 at a short distance is formed by the ultrasonic waves passing through the central portion, and the focal point F2 is formed at a long distance by the ultrasonic waves passing through both sides of the central portion. That is, a plurality of focal points are formed at the same time, and the spatial resolution can be improved over a wide range from a short distance to a long distance. Of course, in some cases, only the elements 25b and 25c may be subjected to the wave transmitting / receiving operation to form only the long-distance focal point F2. Alternatively, the focus formation condition may be switched between transmission and reception. Incidentally, in the electronic scanning direction, since focusing is performed electronically, this is performed in the same manner as in the related art. Specifically, at the time of transmission, transmission multi-stage focus is executed as needed, and at the time of reception, reception dynamic focus is applied as needed.
[0038]
As described above, according to the ultrasonic diagnostic apparatus of the present embodiment, it is possible to switch the focus formation condition only by switching the size of the transmission / reception wave aperture in the elevation direction. , Or the spatial resolution can be improved from a short distance to a long distance. Of course, by applying the electronic focus control in the elevation direction together with the operation of the acoustic lens 12, it is also possible to realize various beam controls in the elevation direction. In the embodiment shown in FIGS. 1 and 2, in the electronic scanning direction, the respective vibrating elements 25 are linearly arranged to realize electronic linear scanning. Sector scanning may be performed, or each of the transducers 25 may be arranged in an arc to form an electronic convex ultrasonic probe. Also in this case, various focus forming conditions can be set by making the shapes of the front surface 18 and the rear surface 20 of the acoustic lens 12 as desired as described above.
[0039]
In the above embodiment, the so-called array vibrator has been described. However, the above principle can be applied to a circular single vibrator or a circular annular array vibrator. The acoustic lens is used, but multi-focus can be realized by appropriately setting the curvature of the central portion of the front surface and the entire curvature of the rear surface.
[0040]
【The invention's effect】
As described above, according to the present invention, it is possible to set a plurality of focal points in the elevation direction while improving the adhesion to the living body.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main configuration of an ultrasonic probe according to the present invention.
FIG. 2 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Front cover part, 12 acoustic lens, 14 skirt part, 15 surface, 16 center part, 18 flat part, 20 back surface, 22 matching layer, 24 ultrasonic transducer (array transducer), 26 transmitting / receiving part, 27 backing layer .

Claims (8)

An acoustic lens having a first shape whose front surface on the living body side forms a first focal length and a second shape whose back surface on the non-living body side forms a second focal length;
A wave transmitting / receiving unit provided on the back side of the acoustic lens and having a shape along the second shape;
An ultrasonic probe comprising: The ultrasonic probe according to claim 1,
The first shape is formed in a first partial region in a region where ultrasonic waves pass, and has a first curvature and is convex toward the living body,
The ultrasonic probe is characterized in that the second shape is formed over the entire area through which the ultrasonic wave passes, and has a second curvature and is concave toward the living body. The ultrasonic probe according to claim 1 or 2,
The ultrasonic probe according to claim 1, wherein the first focal length is smaller than the second focal length. The ultrasonic probe according to claim 2,
The ultrasonic probe according to claim 2, wherein the transmitting / receiving section has an overall shape curved at the second curvature along the second shape. The ultrasonic probe according to claim 4,
An ultrasonic probe comprising a backing layer having an upper surface curved along the shape of the back surface of the wave transmitting and receiving unit. The ultrasonic probe according to claim 1,
The transmitting and receiving unit includes a plurality of piezoelectric elements aligned in the electronic scanning direction,
The ultrasonic probe according to claim 1, wherein the first shape and the second shape are curved in an elevation direction orthogonal to the electronic scanning direction. The ultrasonic probe according to claim 4,
An ultrasonic probe, wherein each of the piezoelectric elements is constituted by a group of divided elements arranged in the elevation direction. In an ultrasonic diagnostic apparatus including an apparatus main body and an ultrasonic probe connected thereto,
The ultrasonic probe,
An acoustic lens having a first shape for forming a near focal length at the center of the front surface on the living body side, and a second shape for forming the far focal length on the entire back surface on the non-living body side;
A vibrator provided on the back side of the acoustic lens and having a shape along the second shape;
Including
The vibrator is composed of a plurality of piezoelectric elements aligned in the electronic scanning direction, each piezoelectric element is composed of a group of divided elements aligned in an elevation direction orthogonal to the electronic scanning direction,
The apparatus body is configured to transmit and receive a central portion of the element group constituting each of the piezoelectric elements when performing near focus processing, and configure each of the piezoelectric elements when forming a long focal length. An ultrasonic diagnostic apparatus, comprising: an aperture control unit for transmitting and receiving the entire element group.

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