JPH02297347A - Ultrasonic wave contactor - Google Patents

Abstract

PURPOSE:To improve durability of a sound lens by increasing the resistiveness for chemicals and oil resistance of the sound lens and reduce the ultrasonic wave transmission loss and improve the sensitivity of the receiving and transmission of the ultrasonic wave by forming the sound lens from the fluorinated rubber consisting of tetrafluoroethylene propylene copolymer. CONSTITUTION:An intermediate layer 3 is installed onto the upper surface of an ultrasonic wave vibrator 2, and a sound lens 4 is installed onto the upper surface of the intermediate layer 3. The sound lens 4 converges the ultrasonic wave beams on a plane crossing at right angle with the arrangement direction of the vibrator element of the ultrasonic vibrator 2 and prevents the existence of an air layer which attenuates the ultrasonic wave beam between an ultrasonic wave generating source and a living body. The sound lens 4 is made of the fluorinated rubber consisting of tetrafluoroethylene propylene copolymer. Therefore, the durability of the sound lens 4 can be improved, and the sensitivity in the receiving/transmission of the ultrasonic wave can be improved by reducing the ultrasonic wave transmission loss.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an ultrasonic probe in which an acoustic lens is fixed to the surface of an ultrasonic transducer. The present invention relates to an ultrasonic probe that can reduce propagation loss and improve the sensitivity of ultrasonic transmission and reception.

[Conventional δ technology]

As a conventional ultrasonic probe, the Japanese Patent Publication No. 60-52823
As described in the publication, there is provided a holding body, ultrasonic transducers arranged on the holding body, and a structure that is fixed to the surface of the ultrasonic transducers so that the outer surface thereof is aligned with the direction in which the ultrasonic transducers are arranged. A device is known that is equipped with an acoustic lens made of silicone rubber and formed into a substantially arcuate shape so as to bulge outward in orthogonal cross sections. In the ultrasonic probe having such a configuration, the ultrasonic beam can be electronically focused in a plane that includes the arrangement direction of the ultrasonic transducers and is perpendicular to the surface of the ultrasonic transducers. The acoustic lens can focus the ultrasound beam in a plane perpendicular to the arrangement direction of the ultrasound transducers, and the acoustic lens also creates an air layer between the ultrasound source and the living body that attenuates the ultrasound beam. intervention was prevented. The acoustic lens in conventional ultrasound probes of this type has a convex surface shape to obtain a lens effect, so the ultrasound propagation speed is slower than that of a living body, and the acoustic impedance with the body surface of the subject is reduced. Silicone rubber is usually used as the material because it achieves acoustic matching and increases the propagation efficiency of ultrasonic waves.

However, conventional acoustic lenses made of silicone rubber cannot be said to have high chemical resistance or oil resistance, and have a problem in that they cannot withstand long-term use under actual conditions of use. In other words, when performing ultrasonic diagnosis, an anti-attenuation agent, such as ultrasonic jelly, liquid paraffin, or olive oil, through which ultrasonic waves easily conduct, is usually applied to the surface of the probe or the surface of the subject. Since the probe is moved and scanned along the surface of the subject, the surface of the acoustic lens is eroded or corroded by the anti-attenuation agent, reducing the life of the probe.

On the other hand, in order to solve the above problems, as described in Japanese Patent Application Laid-open No. 168547/1983,
Acoustic lenses using fluorine-based silicone rubber have been proposed as materials. This fluorine-based silicone rubber is
Its specific gravity is about 1.3 to 1°5, and the speed of sound propagating inside it is about 10 QOm/s, so that a lens effect similar to that of a conventional acoustic lens made of silicone rubber can be obtained.

The acoustic lens made of fluorine-based silicone rubber has good chemical and oil resistance, so it can withstand long-term use without being eroded or corroded by the anti-attenuation agent that adheres to the probe surface. , the lifespan of the probe can be improved.

[Problem to be solved by the invention]

However, in the acoustic lens made of fluorine-based silicone rubber described in JP-A-56-168547, the ultrasonic propagation loss of the fluorine-based silicone rubber is relatively large. When comparing the characteristics of a material with a thickness of 2III11 against sound waves, it was found that the attenuation of the signal was approximately 5 to 6 dB greater during the round trip than with a conventional acoustic lens made of silicone rubber. Therefore, the sensitivity of the ultrasonic probe for transmitting and receiving ultrasonic waves may be reduced.

Therefore, the present invention solves these problems and provides an ultrasonic probe that can improve the durability of the acoustic lens, reduce ultrasonic propagation loss, and improve the sensitivity of ultrasonic transmission and reception. The purpose is to

j- [Means for Solving the Problems] In order to achieve the above object, the ultrasonic probe according to the present invention has a composition on the surface of the ultrasonic transducer that has a composition whose ultrasonic propagation velocity is lower than the propagation velocity in the living body. In an ultrasonic probe to which an acoustic lens made of a substance is fixed, the acoustic lens is made of fluororubber of tetrafluoroethylene/propylene copolymer.

[For production]

In the ultrasonic probe constructed in this way, the acoustic lens is made of fluororubber, which is a tetrafluoroethylene propylene copolymer, and the properties of this fluororubber improve the durability of the acoustic lens and improve the propagation of ultrasonic waves. It is possible to reduce the loss and improve the sensitivity of ultrasonic transmission and reception.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an internal structural diagram showing an embodiment of an ultrasonic probe according to the present invention. In the figure, a holder 1 serves as a base member for arranging ultrasonic transducers 2, which will be described later, and is formed into a flat plate shape with an appropriate thickness. Ultrasonic transducers 2 are arranged on the upper surface of the holder 1. This ultrasonic transducer 2 transmits an ultrasonic beam toward a subject and receives reflected echoes from a target part of the subject. A narrow rod-shaped transducer element is attached to the holder 1 A large number of them are arranged perpendicularly to the longitudinal direction. An intermediate layer 3 is provided on the upper surface of the ultrasonic transducer 2 . This intermediate layer 3 is for acoustic matching between the ultrasound transducer 2 and a living body as a subject, and is made of a material having an acoustic impedance intermediate between that of the ultrasound transducer 2 and the living body. The thickness thereof is formed to correspond to 1/4 of the wavelength of the ultrasonic waves used. An acoustic lens 4 is provided on the upper surface of the intermediate layer 3. This acoustic lens 4 focuses the ultrasonic beam in a plane perpendicular to the arrangement direction of the transducer elements of the ultrasonic transducer 2, and also provides air between the ultrasonic generation source and the living body to attenuate the ultrasonic beam. This prevents the intervention of the layer, and is made of a material whose ultrasonic propagation velocity is slower than that in the living body, so that its outer surface bulges outward in a cross section perpendicular to the arrangement direction of the transducer elements. It is formed almost in the shape of an arc.

In the present invention, the acoustic lens 4 is made of fluororubber, which is a tetrafluoroethylene/propylene copolymer. This fluororubber is made of tetrafluoroethylene (C
It is a copolymer of 2F4) and propylene (C3HG) arranged almost alternately due to their monomer reactivity, and has a structure as shown in Figure 2. Because the methyl groups of propylene are randomly coordinated, this copolymer has poor quality and exhibits rubber elasticity despite the regular alternating heptad arrangement. In addition, almost all propylene units are sandwiched between tetrafluoroethylene units, making the polymer thermally and chemically stable.

This fluororubber is commercially available under the trade name Aflas (registered trademark). Table 1 shows a comparison of the chemical resistance and oil resistance between this fluororubber under the trade name Aflas and conventional silicone rubber. Table 2 also shows a comparison of gas permeability.

Table 1 (Comparison of Volume Change Rate %) Table 2 [Unit: (cc-am/af-see
・anHg) It can be seen that it is superior to silicone rubber in most items, including oil resistance and gas permeability.

In this way, the acoustic lens 4 made of fluororubber of tetrafluoroethylene/propylene copolymer has a sound velocity of about 1135 m/s in the fluororubber, which is about 150 m/s.
0m/s), and the acoustic impedance (specific gravity x speed of sound) is ρc = 1.59 x 10' kg/I・S
can be made almost equal to that of a living body.

In addition, the propagation loss of ultrasonic waves is 1
Approximately 7 compared to 8 to 24 dB/■ (frequency f = 2M ratio)
It is as small as dB/am (f = 2 Mm). Note that when the frequency of ultrasonic waves becomes high, for example f = 7.5 MHz, the ultrasonic propagation loss of fluorine-based silicone rubber increases from 30 to 100 dB.
/■, whereas in the case of the fluororubber of the present invention, it is as small as about 23 dB / mark, and the difference becomes large.

FIG. 3 is an external view showing an example in which the ultrasonic probe having the internal structure shown in FIG. 1 is applied to a surgical ultrasonic probe 5. As shown in FIG.

In FIG. 3, the case 6 exposes only the outer surface of the acoustic lens 4 shown in FIG. 1 and covers all other parts.

The conducting wire connected to the ultrasonic transducer 2 within the case 6 is taken out to the outside via a cable 7. Ultrasonic diagnostic equipment equipped with such a surgical ultrasound probe 5 is considerably smaller than other diagnostic imaging equipment, and can be easily carried into the operating room, taking advantage of its real-time performance. , intraoperative application has become widespread. That is, the surgical ultrasonic probe 5 has come to be applied directly to an organ during surgery to be used to locate the affected area and determine the surgical method. When used in this way, the ultrasonic probe is sterilized before use by applying a chemical solution or leaving it in pressurized gas (usually ethylene oxide gas). .

For such sterilization treatment, it is preferable that the acoustic lens 4 has high chemical resistance, low swelling property, and sufficiently low gas permeability. And as shown in Table 2, those properties are provided. The case 6 is usually made of a different material from the acoustic lens 4, but the case 6 is not limited to this, and like the acoustic lens 4, the case 6 is also made of fluororubber made of tetrafluoroethylene-propylene copolymer. Alternatively, the acoustic lens 4 and the case 6 may be formed into an integral structure.

4 and 5 are explanatory diagrams showing an example in which the ultrasound probe having the internal structure shown in FIG. 1 is applied to an ultrasound probe 8 for use in a body cavity. FIG. 4 is an external view showing the entire device, in which the ultrasonic transducer 2 shown in FIG. 1 and other parts are housed inside a case 9 at the distal end, and
The conductive wire connected to is taken out to the outside by a cable 10, and a connector 11 is provided for connecting the cable 10 to the main body of the ultrasonic diagnostic apparatus (not shown). Also, the fifth
Figures (a) and (b) show the tip of the intracorporeal ultrasound probe 8 that is inserted into the body cavity of a subject along the fingertip of a doctor, etc.; It is a side view showing a state in which the fingertip 12 of a doctor or the like is placed along the back side of the case 9 at the tip, and FIG.
9 is a bottom view showing a state in which the outer surface of the case 9 is exposed from the case 9. FIG. Such an intrabody cavity ultrasound probe 8 is also sterilized in the same manner as the surgical ultrasound probe 5 because its tip is inserted into the body cavity of the subject.

In FIG. 1, the ultrasonic transducer 2 is shown as having a large number of narrow rod-shaped transducer elements arranged perpendicularly to the longitudinal direction of the holder 1, but the present invention is not limited to this. For example, the present invention can be similarly applied to a single disk-shaped ultrasonic transducer 2.

〔Effect of the invention〕

Since the present invention is constructed as described above, by forming the acoustic lens 4 with fluororubber of tetrafluoroethylene/propylene copolymer, the properties of this fluororubber make the acoustic lens 4 resistant to chemicals and oil. It is possible to increase the durability and improve the durability, and also to reduce the ultrasonic propagation loss and improve the sensitivity of ultrasonic transmission and reception. Therefore, for example, the surgical ultrasonic probe 5 or the intracorporeal ultrasonic probe 8 can be sufficiently sterilized, and the lifespan of these ultrasonic probes can be improved. can.

[Brief explanation of drawings]

Figure 1 is an internal structure diagram showing an embodiment of the ultrasonic probe according to the present invention, Figure 2 is an explanatory diagram showing the chemical structure of fluororubber, which is a tetrafluoroethylene propylene copolymer, and Figure 3 is 1
An external view showing an example in which the ultrasonic probe with the internal structure shown in the figure is applied to a surgical ultrasonic probe. FIG. 2 is an explanatory diagram showing an example in which the probe is applied to an ultrasound probe for use in a body cavity. 1...Holding body, 2...Ultrasonic vibrator, 3...
Intermediate layer, 4...Acoustic lens, 6,9...Case, 7゜10...Cable.

Claims (1)

[Claims] In an ultrasonic probe in which an acoustic lens made of a substance whose ultrasonic propagation velocity is slower than that in a living body is fixed to the surface of an ultrasonic transducer, the acoustic lens is made of tetrafluoroethylene propylene copolymer. An ultrasonic probe characterized by being made of fluororubber.