WO2008068932A1

WO2008068932A1 - Ultrasonic probe

Info

Publication number: WO2008068932A1
Application number: PCT/JP2007/066555
Authority: WO
Inventors: Mitsuhiro Fujiwara
Original assignee: Okusonic Corporation
Priority date: 2006-12-08
Filing date: 2007-08-27
Publication date: 2008-06-12
Also published as: JPWO2008068932A1; JP4932851B2

Abstract

An ultrasonic probe adapted to carry out ultrasonic beam convergence by means of an acoustic lens. In the probe, in a hermetically sealed casing, at least portion constituting an ultrasonic incident and exit surface of which consists of a material ensuring appropriate sound transmission, two types of liquid layers that are mutually insoluble, exhibit different acoustic velocities and are conductive in one layer while insulating in the other layer are accommodated in the state of being superimposed one upon the other in the wave transmitting/receiving direction with an interface formed therebetween. Further, not only is a noncontact electrode covered with an insulating layer disposed around the two types of liquid layers, but also there is disposed a contact electrode brought into conductive contact with the conductive liquid layer. The configuration of the interface can be changed by voltage application between the noncontact electrode and the contact electrode, thereby rendering the focus of the acoustic lens variable.

Description

Specification

Ultrasonic probe

Technical field

[0001] The present invention relates to an ultrasonic probe in which an acoustic lens is arranged in a transmission / reception direction of an ultrasonic transmission / reception unit, and is particularly useful for visualizing and observing a state of a human body or a domestic animal. It relates to what is effective.

Background art

[0002] When diagnosing the inside of a human body or an animal, while transmitting an ultrasonic panel from the ultrasonic probe toward the inside of the body, receiving an ultrasonic reflected wave from the inside of the body, The state of this is being visualized in real time.

[0003] The main part of the ultrasonic probe is composed of an ultrasonic wave transmitting / receiving unit that oscillates ultrasonic waves and receives ultrasonic reflected waves, and an acoustic lens that performs ultrasonic beam convergence. The ultrasonic transmission / reception unit is configured using a piezoelectric vibrator or the like (see Patent Document 1). As the acoustic lens, an acoustic propagation material having a sound velocity different from that of the observation object, for example, a solid material such as silicon resin or epoxy resin formed into a convex shape or a concave shape is used (see Patent Document 2).

FIG. 9 shows a schematic configuration of a conventional ultrasonic probe. In this figure, (a) is an external perspective view of the entire probe, (b) is a sectional view in the direction AA, and (c) is a sectional view in the direction BB.

[0005] The ultrasonic probe shown in the figure includes an ultrasonic transmission / reception unit 10 in which a large number of ultrasonic transducers 11 are arranged in a line, and an ultrasonic wave transmitted from each ultrasonic transducer 11 to each other. An acoustic lens 201 for converging the sound wave to the observation part is used. The acoustic lens 201 is a so-called cylindrical lens, and is formed so as to converge the ultrasonic beam on one axis parallel to the arranged IJ line.

[0006] In the ultrasonic probe, when diagnosing the inside of a human body or an animal, the emission surface 22 of the acoustic lens 201 is brought into close contact with the surface of the observation target. For this reason, the acoustic lens 201 has a low acoustic propagation loss and uses a material having a sound velocity different from that of the observation target. [0007] The acoustic lens 201 shown in the figure uses a soft material 61 such as silicon resin whose sound speed is slower than that of the human body as a lens material, and uses a convex cylindrical cylindrical lens with a lens shape as a lens. To obtain a convex lens effect that converges the ultrasonic beam to a predetermined depth of!

[0008] In an ultrasonic probe that uses the exit surface of the acoustic lens 201 in contact with the observation target, the acoustic lens 201 is a concave surface as shown in FIG. 10 in order to correspond to the surface shape of the observation target. Sometimes it has to be a cylindrical 'lens. In this case, the acoustic lens 201 is formed using a hard material 62 having a high sound speed, for example, an epoxy resin having a sound speed faster than that of the human body.

Patent Document 1: JP 2000-139916

Patent Document 2: JP 2005-245771

Disclosure of the invention

Problems to be solved by the invention

[0009] However, the ultrasonic probe described above has the following problems.

[0010] That is, in ultrasonic diagnosis or the like, a force S that accurately determines a position such as a depth of an observation site and further needs to adjust or change the position S. It is necessary to be able to smoothly variably adjust the beam convergence position.

However, since the above-described ultrasonic probe is configured using a solid-type acoustic lens 201 made of a solid material, the convergence position of the ultrasonic beam within the observation target is determined by the acoustic lens 201. It is fixedly determined by the material, that is, the sound speed, the lens shape, and the sound speed of the observation target. For this reason, there is a problem that it is difficult to adjust or change the convergence position of the ultrasonic beam.

The lens shape of the acoustic lens 201 is determined by the lens material and the sound speed ratio of the observation target. For example, a relatively flexible material such as silicon resin has a slower sound speed than the object to be observed. Therefore, in order to obtain the lens effect of converging ultrasonic waves with an acoustic lens using this material, it is necessary to have a convex lens shape as shown in FIG.

On the other hand, in the diagnosis of a human body or the like, a concave lens shape as shown in FIG. 10 may be more convenient. In this case, in order to obtain the lens effect of focusing the ultrasonic wave, On the contrary, it is necessary to use a material having a higher sound speed than the object to be observed. However, such materials are hard materials such as epoxy resins, and are not suitable for use in close contact with the human body.

[0014] When used in contact with the human body, a relatively flexible material such as silicon resin is preferable, but in this case, it cannot be made concave according to the surface shape of the human body! /, And! / This causes a contradiction.

As described above, the above-described ultrasonic probe has a problem that it is difficult to select and optimize the material and shape of the acoustic lens.

[0015] As a means to vary the convergence position (focus) of an ultrasonic beam, a mechanical drive system using a motor (mechanical 'focusing) has been proposed in the past. This type of mechanical drive system produces acoustic noise. Likely to happen. This noise generation becomes an obstacle when detecting weak ultrasonic reflected waves with high sensitivity and high S / N ratio. This disturbance noise is generated not only when the mechanical drive system is in operation, but also when the drive system is not in operation. It has been found that can be a hindrance to the diagnosis by ultrasonic acoustics.

[0016] The present invention solves the above-described problems, and accurately determines a position such as the depth of an observation site in ultrasonic diagnosis and adjusts the position! / Can be quickly and smoothly performed in real time during observation, and the material and shape of the acoustic lens that can be in contact with the observation target can be optimized according to the state of the observation target. It is an object of the present invention to provide an ultrasonic probe capable of improving the accuracy of diagnosis (S / N ratio) by suppressing the generation of noise, which is a major obstacle.

[0017] Other objects and configurations of the present invention will become apparent from the description of the present specification and the accompanying drawings.

Means for solving the problem

In order to solve the above problem, the present invention provides the following means.

[0019] (1) In an ultrasonic probe in which an acoustic lens is arranged in the transmission / reception direction of the ultrasonic transmission / reception unit so as to perform ultrasonic beam convergence, the acoustic lens includes at least ultrasonic input / output. The surface part has a sealed casing made of a material with good sound transmission. In one singe, two liquid layers, which are insoluble and have different sound speeds, one of which is conductive and the other is insulating, are accommodated in a state where they are stacked in the above transmission / reception direction while forming an interface between them. A non-contact electrode covered with an insulating layer is disposed around the two types of liquid layers, and a contact electrode in conductive contact with the conductive liquid layer is disposed between the non-contact electrode and the contact electrode. An ultrasonic probe characterized in that the focal point of the acoustic lens is varied by changing the interface shape by applying a voltage of.

[0020] (2) In the above means (1), the ultrasonic wave transmitting / receiving unit includes ultrasonic transducers arranged in a line, and the acoustic lens is parallel to an arrangement IJ line of the ultrasonic transducers. An ultrasonic probe characterized by forming a cylindrical lens that converges an ultrasonic beam on one axis.

(3) In the means (2), the ultrasonic contact is characterized in that the non-contact electrode forms a pair of independent electrodes facing each other with the two types of liquid layers interposed therebetween. Tentacles.

[0022] (4) The ultrasonic probe according to any one of the means (1) to (3), wherein water is used for the conductive liquid layer and oil is used for the insulating liquid layer.

[0023] (5) An ultrasonic probe characterized in that, in the means (4), the conductive liquid layer is disposed on the ultrasonic emission surface side.

(6) In any one of the above means (1) to (5), an ultrasonic probe characterized in that an auxiliary acoustic lens comprising a solid material force is installed on the sound axis of the acoustic lens. Child.

[0025] (7) In any one of the above means (1) to (6), an acoustic matching layer is installed between the ultrasonic transmission / reception unit and the acoustic lens, and at least a part of the acoustic matching layer is provided. An ultrasonic probe characterized in that the layer is formed of the casing.

[0026] (8) In any one of the above means (1) to (7), at least the partial force S of the casing located on the emission surface side of the acoustic lens, and the acoustic for matching the acoustic impedance with the observation target An ultrasonic probe characterized in that its material and / or thickness is set so as to form a match.

The invention's effect

[0027] An ultrasonic probe that performs ultrasonic beam focusing with an acoustic lens accurately determines the position of the observation site in ultrasonic diagnosis, etc., with a simple and low-cost configuration. In addition, it is possible to adjust the position and change the position quickly and smoothly in real time during observation, and to optimize the material and shape of the acoustic lens that can be in contact with the observation target according to the state of the observation target. Furthermore, it is possible to improve the diagnostic accuracy (S / N ratio) by suppressing noise generation, which is a major obstacle in ultrasonic diagnosis.

The operation / effect other than the above will be apparent from the description of the present specification and the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a schematic configuration of a first embodiment of an ultrasonic probe to which the technology of the present invention is applied. In the same figure, (a) is an external perspective view of the entire probe, (b) is a cross-sectional view in the direction AA, and (c) is a cross-sectional view in the direction BB.

[0030] The ultrasonic probe shown in the figure includes an ultrasonic transmission / reception unit 10 in which a large number of ultrasonic transducers 11 are arranged in a line, and an ultrasonic wave transmitted from each ultrasonic transducer 11 to each other. The main part is composed of the acoustic lens 20 for converging the sound wave to the observation part. The acoustic lens 20 is a so-called cylindrical lens, and is formed so as to converge an ultrasonic beam on one axis parallel to the array line.

[0031] In this case, although detailed illustration and explanation are omitted, each ultrasonic transducer 11 is acoustically shielded from the surroundings and transmits and receives ultrasonic waves acoustically independently without interfering with each other. The sound absorbing material is installed using a backing material so that it can be performed.

The acoustic lens 20 has a sealed casing 25 made of a hard material with good acoustic transmission, for example, polyimide resin, at least at the portions that become the ultrasonic incident / exit surfaces 21 and 22. The casing 25 is a hard case having a self-holding property, and is formed in a long shape to form a cylindrical lens, and its cross section is formed in a force-like shape. In this casing 25, the two kinds of liquid layers 41 and 42, which are insoluble and have different sound speeds, one of which is conductive and the other is insulating, form the interface (liquid phase interface) between them, and send and receive the above-mentioned transmission and reception. It is housed in a stacked state in the wave direction.

[0033] Since the conductive liquid layer 42 is located on the observation object side such as a human body, water (aqueous solution) is preferable. The insulating liquid layer 41 does not mix even when it comes into contact with the water of the conductive liquid layer 42, and can stably form a clear liquid phase interface without dissolving each other. Oil with slow sound speed is particularly suitable. In this case, the water speed of the conductive liquid layer 42 and the sound velocity in the living body such as a human body are almost the same, and thus the insulating liquid layer 41 exhibits an acoustic lens effect.

[0034] Non-contact electrodes 31 and 32 covered with an insulating layer are arranged around the two types of liquid layers 41 and 42, and a contact electrode 33 that is in conductive contact with the conductive liquid layer 42 is provided. Yes. The non-contact electrodes 31 and 32 are formed by embedding a planar conductor such as a metal plate in the side wall 23 facing the casing 25 in the width direction, thereby surrounding the two liquid layers 41 and 42 through a thin insulating layer. Non-conductive contact. The contact electrode 33 is installed on the inner wall surface at the longitudinal end of the casing 25 and is in direct contact with the conductive liquid layer 42.

[0035] Out of the inner wall surface of the casing 25, the three inner wall surfaces excluding the ultrasonic wave emitting surface 22 are provided with water repellency. As shown in the figure, the water repellent effect that acts on the inner wall surface of the casing in a steady state stabilizes the convex portion with a thick central bulge!

In order to efficiently transmit and receive ultrasonic waves, it is necessary to achieve acoustic impedance matching between the ultrasonic transducer 11 and the acoustic lens 20. In order to achieve this matching, an acoustic matching layer is usually installed, but this acoustic matching layer sets the material and thickness of the ultrasonic incident surface 21 part interposed between the ultrasonic transducer 11 and the acoustic lens 10. Similarly, when acoustic impedance matching is required between the acoustic lens 20 and the observation target that can be formed, the material of the ultrasonic output surface 22 part interposed between the two is similarly used. The acoustic matching layer can be formed by setting the thickness.

[0037] As described above, the ultrasonic incident surface 21 and the ultrasonic output surface 22 of the acoustic lens 20 are forces that can be used as at least a part of the acoustic matching layer. If the acoustic wave output surface 22 is formed of two or more layers and the acoustic impedance is changed stepwise, a good acoustic matching layer with little reflection loss can be formed by the casing 25 alone.

FIG. 2 shows the operating state of the ultrasonic probe shown in FIG. 1, particularly the behavior of the acoustic lens.

First, as shown in FIG. 2 (a), in the off state (steady state) in which no voltage is applied between the non-contact electrodes 31 and 32 and the contact electrode 33, the conductive liquid layer 42, which is water, The surface tension of the liquid Due to the water repellency of the inner wall surface of the casing 25, a convex surface state is exhibited. Accordingly, the insulating liquid layer 41, which is oil, exhibits a concave state.

[0040] In this case, the sound velocity of the observation object is almost the same as that of the conductive liquid layer 42, and the sound velocity of the insulating conductor layer 41 is relatively low, so that the concave insulating liquid layer 41 diffuses the acoustic beam. Form a concave lens effect. In other words, the acoustic lens 42 in this case has a negative focal length.

Next, as shown in FIG. 2 (b), when a certain voltage VI is applied between the non-contact electrodes 31 and 32 and the contact electrode 33, the conductive liquid layer 42 and the non-contact electrodes 31 and 32 are connected. By the action of the electric field, a force is applied to the conductive liquid layer 42 to spread over the non-contact electrodes 31 and 32. A so-called electrowetting phenomenon is activated. As a result, the conductive liquid layer 42 flows and deforms from a convex shape to a flat shape, and accordingly, the insulating liquid layer 41 flows and deforms from a concave shape to a flat shape.

Thereby, the concave lens effect in the insulating liquid layer 41 is lost, and the focal length of the acoustic lens 42 becomes infinite. That is, in this case, the ultrasonic wave is transmitted linearly as it is.

[0043] As shown in FIG. 2C, when the applied voltage V1 between the non-contact electrodes 31 and 32 and the contact electrode 33 is increased, the action of the electrowetting phenomenon is caused. As it appears strongly, the conductive liquid layer 42 flows and deforms from a flat shape to a concave surface, and the insulating liquid layer 41 flows and deforms from a flat shape to a convex surface. This deformation causes the insulating liquid layer 41 to form a convex lens effect that converges the acoustic beam. In other words, the acoustic lens 42 in this case has a positive focal length.

As described above, in the above-described ultrasonic probe of the present invention, the ultrasonic beam generated by the acoustic lens 20 can be obtained simply by operating the applied voltage VI between the non-contact electrodes 31 and 32 and the contact electrode 33. The convergence position can be easily variably set.

[0045] Thereby, with a simple and low-cost configuration, it is possible to accurately determine the position such as the depth of the observation site in sonography, etc., and to adjust or change the position quickly and in real time during observation. It becomes possible to carry out smoothly.

[0046] In the ultrasonic diagnosis, the noise generated by the apparatus itself greatly hinders the diagnosis. However, the ultrasonic probe according to the present invention is a complicated and troublesome maintenance and noise generating device. By not relying on the mechanical drive system, it can be configured simply and at low cost, and it can significantly reduce the noise and greatly improve the diagnostic accuracy (S / N ratio).

[0047] Furthermore, since the ultrasonic probe of the present invention can variably set the convergence position of the ultrasonic beam in real time, the ultrasonic probe is used to observe the affected area while observing the affected area. It is also suitable for use in irradiation treatment. In other words, treatment by local irradiation of ultrasound can be performed while making a diagnosis.

[0048] When the ultrasonic probe is used in contact with the human body, heat generation in the ultrasonic probe becomes a problem. However, if water is used for the conductive liquid layer 42 disposed on the side in contact with the human body, the effect of suppressing the temperature rise at least at the portion in contact with the human body can be obtained due to the water cooling effect.

In addition, since the lens effect of the acoustic lens 20 is obtained by the liquid layers 41 and 42 in the casing 25, the material and shape of the casing 25 can be selected freely. Therefore, for example, as shown in FIG. 3 or FIG. 4, the ultrasonic wave emission surface 22 that comes into contact with an observation target such as a human body can be arbitrarily shaped such as a flat shape or a concave shape without being restricted by the type of material. It is possible to form. As a result, the material and shape of the acoustic lens 20 brought into contact with the observation target can be optimized according to the state of the observation target.

[0050] Convex-shaped acoustic lenses using silicon rubber have the disadvantage that the beam pattern changes due to deformation due to external pressure due to pressing during use and wear due to friction during use. In the acoustic lens according to the invention, since there is no restriction on the material for forming the casing 25 as described above, a hard material is used for the material to prevent deformation due to external pressure and abrasion due to friction. ¾] to obtain the result of preventing the change of the beam pattern.

[0051] Further, as for the overall shape of the ultrasonic probe, for example, a curved shape as shown in FIG. 6 other than a straight shape as shown in FIG. 5 is arbitrarily selected without impairing the acoustic lens effect. It is possible.

FIG. 7 shows a second embodiment of the present invention. The second embodiment is basically the same as the first embodiment, but the non-contact electrodes 31 and 32 are used as a pair of independent electrodes facing each other with the two liquid layers 41 and 42 interposed therebetween. There is a feature. [0053] In this case, as shown in (a) or (b) of the figure, by making the voltages VI and V2 applied to the one 41 and the other 42 of the pair of independent electrodes 41 and 42 different from each other, A force S can be applied to the conductive liquid layer 42 while it is flow-deformed while being biased to one of the non-contact electrodes 31 or 32.

[0054] Thereby, in addition to the focal length for converging the ultrasonic beam, the beam direction, that is, the sound axis direction, can be easily variably set by operating the applied voltages VI and V2.

This is very effective, for example, for changing the observation position and expanding the range, and greatly contributes to improving the accuracy and efficiency of diagnosis using an ultrasonic probe.

FIG. 8 shows a third embodiment of the present invention. As shown in (a) or (b) of the same figure, the ultrasonic probe according to the present invention is an auxiliary sound made of a solid material on the sound axis of the acoustic lens 20 using the liquid layers 41, 42. The lens 202 may be installed and used.

In this case, if the auxiliary acoustic lens 202 is used as a correction lens and the lens accuracy of the acoustic lens 20 is compensated, the accuracy of the ultrasonic probe can be further improved. Alternatively, if the auxiliary acoustic lens 202 has a convex lens effect, it is possible to obtain an optical bias effect in which the convex lens effect starts to appear from the point where the applied voltage is zero.

As described above, the present invention has been described based on the representative examples. However, the present invention can have various modes other than those described above. For example, the present invention can be suitably applied to an ultrasonic probe in which ultrasonic transducers are two-dimensionally arranged.

Industrial applicability

[0058] In an ultrasonic probe that performs ultrasonic beam focusing with an acoustic lens, it is possible to accurately determine a position such as the depth of an observation site in ultrasonic diagnosis or the like with a simple and low-cost configuration, and Position adjustment or change can be performed quickly and smoothly in real time during observation, and the material and shape of the acoustic lens that can be in contact with the observation target can be optimized according to the state of the observation target. It is possible to improve the accuracy (S / N ratio) of the diagnosis by suppressing the generation of noise, which is a major obstacle in ultrasonic diagnosis.

Brief Description of Drawings

[0059] FIG. 1 is a perspective view and a cross-sectional view showing a schematic configuration of the ultrasonic probe according to the first embodiment of the present invention. FIG.

2 is a cross-sectional view showing the operation of the ultrasonic probe shown in FIG.

FIG. 3 is a cross-sectional view showing an example in which an ultrasonic wave emission surface is formed flat in the present invention.

FIG. 4 is a cross-sectional view showing an example in which an ultrasonic wave emission surface is formed in a concave shape in the present invention.

FIG. 5 is a cross-sectional view showing an example in which the entire ultrasonic probe has a straight shape in the present invention.

FIG. 6 is a cross-sectional view showing an example in which the entire ultrasonic probe is bent in the present invention.

FIG. 7 is a sectional view showing another operation example of the ultrasonic probe according to the present invention.

FIG. 8 is a cross-sectional view showing a waist portion of an ultrasonic probe according to a second embodiment of the present invention.

FIG. 9 is a perspective view and a cross-sectional view showing a schematic configuration of a conventional ultrasonic probe.

FIG. 10 is a cross-sectional view showing an example in which the emission surface is formed in a concave shape in a conventional ultrasonic probe.

Explanation of symbols

10 Ultrasonic transducer

11 Ultrasonic transducer

20 Acoustic lens (liquid layer)

201 Acoustic lens (solid material)

202 Auxiliary acoustic lens

21 Ultrasonic incident surface

22 Ultrasonic output surface

23 Side wall

25 Casing

31, 32 Non-contact electrode

33 Contact electrode

41 Insulating liquid layer

42 Conductive liquid layer

61 Soft materials such as silicone resin

62 Hard materials such as epoxy resin VI, V2 applied voltage

Claims

The scope of the claims

[1] In an ultrasonic probe in which an acoustic lens is arranged in the transmission / reception direction of the ultrasonic transmission / reception unit to perform ultrasonic beam convergence, the acoustic lens is at least an ultrasonic incident / exit surface The casing has a sealed casing made of a material with good sound transmission, and in this casing there are two types of liquid layers that are insoluble, differ in sound speed, and one is conductive and the other is insulating. In addition, a non-contact electrode covered with an insulating layer is disposed around the two types of liquid layers, while being stacked in the transmission / reception direction while forming an interface. A contact electrode that is in conductive contact with the liquid layer is provided, and the focal point of the acoustic lens is made variable by changing the interface shape by applying a voltage between the non-contact electrode and the contact electrode. Sonic probe.

[2] In Claim 1, the ultrasonic transmission / reception unit includes ultrasonic transducers arranged in a line, and the acoustic lens has ultrasonic waves on one axis parallel to the arranged IJ line of the ultrasonic transducers. Ultrasonic probe characterized by forming a cylindrical 'lens that converges waves

Yes

[3] The ultrasonic probe according to claim 2, wherein the non-contact electrode forms a pair of independent electrodes facing each other with the two types of liquid layers interposed therebetween.

[4] The ultrasonic probe according to any one of claims 1 to 3, wherein water is used for the conductive liquid layer and oil is used for the insulating liquid layer.

[5] The ultrasonic probe according to claim 4, wherein the conductive liquid layer is disposed on an ultrasonic wave emission surface side.

6. The ultrasonic probe according to any one of claims 1 to 5, wherein an auxiliary acoustic lens made of a solid material is installed on the sound axis of the acoustic lens.

[7] Claim: In any one of! To 6, an acoustic matching layer is installed between the ultrasonic transmission / reception unit and the acoustic lens, and at least a part of the acoustic matching layer is formed by the casing. An ultrasonic probe characterized by being formed.

[8] The material according to any one of claims 1 to 7, wherein the material is formed so as to form acoustic matching for acoustic impedance matching with at least a partial force observation target of the casing located on the emission surface side of the acoustic lens. And / or thickness is set Ultrasonic probe.