JP2001037759A - Method for sealing ultrasonic transmission medium in ultrasonic endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently remove air bubbles and to reduce the generation of them after sealing by immersing a tip cap side opening part for covering the ultrasonic probe at the tip of an insertion part into a heated ultrasonic transmission medium and filling the tip cap with the ultrasonic transmission medium by means of executing sucking from the opening part at the side of an operating part. SOLUTION: The mouth piece part 27 of the connection tube 26 of an ultrasonic endoscope 1 is connected to a sucker 31 via a connection mouth piece 33, a connection tube 34 and a change-over stopcock 35. The ultrasonic transmission medium 30 after removing the bubbles is put into a vessel 40, the medium 30 is heated by a heating device 41, a stopper is removed from the opening part 8 and a tip constituting part 5 is immersed in the medium 30. The sucker 31 is operated to suck the medium 30 into the tip cap 7 and a part between a flexible shaft 15 and a flexible tube 22. Then the change-over stopcock 35 is closed, the stopper is attached to the mouth piece part 27 and screwed onto the opening part 8 to seal the ultrasonic transmission medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing an ultrasonic transmission medium to an ultrasonic endoscope capable of obtaining an ultrasonic image and an image observed by a solid-state image sensor or an image guide.

[0002]

2. Description of the Related Art In recent years, for example, Japanese Patent Application Laid-Open No. 57-52443.
JP, JP-A-58-152549, JP-A-58-152549
As shown in JP-169760B, an ultrasonic endoscope capable of ultrasonic diagnosis has been put to practical use. Various structures have been proposed as the structure of the ultrasonic endoscope. One of the structures is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-1905.
As shown in Japanese Patent Publication No. 52, an ultrasonic probe is rotatably provided at a distal end portion of an insertion portion, and the ultrasonic probe is rotated via a flexible shaft or the like extending from a hand operation portion. There is something that performs a mechanical scan.

[0003] In this type of ultrasonic endoscope, a rotatable ultrasonic probe is supported by bearings or the like inside a tip cap for transmitting and receiving ultrasonic waves. Then, a flexible shaft having one end connected to the ultrasonic probe and a flexible tube surrounding the flexible shaft extend into the insertion portion. The other end of the flexible shaft is connected to a rotary drive source such as a servo motor, and rotates the ultrasonic probe.

[0004] An ultrasonic transmission medium such as liquid paraffin is filled in an ultrasonic window portion where the flexible tube and the ultrasonic probe face each other. It has a structure that also serves as a lubricant for the flexible tube.

When enclosing the ultrasonic transmission medium in the distal end cap, the opening provided in the distal end cap is immersed in the ultrasonic transmission medium, and the opening is opened through the opening of the upper flexible tube (operation section side). Perform suction. Then, when no bubbles are mixed in the tip cap, the opening on the operation unit side is closed, and then the opening of the tip cap is closed to seal the ultrasonic transmission medium.

[0006]

In the operation of sealing the ultrasonic transmission medium, it is important that bubbles are not mixed into the tip cap. If air bubbles are mixed in the tip cap, the ultrasonic beam is attenuated in the air bubbles, which causes problems such as an inability to obtain an ultrasonic image.

[0007] However, in the conventional sealing operation of the ultrasonic medium, there are the following problems due to the high viscosity of the ultrasonic transmission medium. That is, if the clearance between the tip cap and the ultrasonic transducer is reduced, bubbles in the tip cap are difficult to escape, so it is necessary to increase the clearance of the ultrasonic probe of the tip cap, and the tip cap becomes thicker. .

Further, when the clearance between the flexible tube and the flexible shaft is reduced, the time for sealing the ultrasonic transmission medium is lengthened, resulting in poor workability. However, when the clearance is increased, the flexible tube becomes thicker, and as a result, the outer diameter of the insertion portion of the ultrasonic endoscope becomes thicker, and the patient suffers more pain.

Also, bubbles inside the flexible shaft are difficult to escape, and there is a risk that bubbles will come out of the tip cap if the flexible shaft is rotated for a long time. Also, if the suction force is increased to efficiently discharge air bubbles from the opening of the operation unit, the flexible tube will be crushed, friction with the flexible shaft will increase, and poor rotation and perforation of the tube will occur. Was causing it to wake up.

As described above, conventionally, the workability of sealing the ultrasonic transmission medium is poor, and air bubbles are generated in the tip cap after sealing, which may adversely affect the ultrasonic image. JP-A-62-179439 has an air vent for removing air bubbles generated in a window material filled with an acoustic medium, and an elastic bag communicating with the window material. A technique is disclosed in which a stopper is provided in a part of an elastic bag, through which a sound medium can enter and exit by inserting a needle, and stops the flow of the acoustic medium after the needle is removed, and air is removed to prevent generation of bubbles. . However, even if this technique is applied, bubbles in the tip cap and the flexible shaft are difficult to escape, and the above-mentioned problems cannot be solved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to improve the sealing operation of an ultrasonic transmission medium, to remove air bubbles easily, and to generate less air bubbles after sealing. It is an object to provide a method for sealing an ultrasonic transmission medium in a mirror.

[0012] The present invention further has a high defoaming effect, very little dissolution of bubbles in the ultrasonic transmission medium, and even if the ultrasonic endoscope is used for a long time, bubbles are not mixed into the tip cap. It is an object of the present invention to provide a method for sealing an ultrasonic transmission medium in an ultrasonic endoscope with a small number.

The present invention further provides a method of sealing an ultrasonic transmission medium in an ultrasonic endoscope, which can increase suction force and can easily perform sealing work even with a highly viscous ultrasonic transmission medium. It is intended to be.

Another object of the present invention is to provide a method of sealing an ultrasonic transmission medium in an ultrasonic endoscope, which can prevent the temperature of the ultrasonic transmission medium from decreasing during the sealing operation.

[0015]

According to the present invention, there is provided a method for sealing an ultrasonic transmission medium in an ultrasonic endoscope, comprising the steps of: forming an opening on a tip cap side for covering an ultrasonic probe provided at a distal end of an insertion portion; And filling the inside of the distal end cap with the ultrasonic transmission medium by immersing the ultrasonic transmission medium in a heated ultrasonic transmission medium and performing suction from the opening on the operation unit side.

Further, for example, before the ultrasonic transmission medium is filled in the tip cap, the ultrasonic transmission medium is defoamed while being heated. Immediately after the defoaming, suction is performed, and Fill the ultrasonic transmission medium.

Further, for example, when the ultrasonic wave transmitting medium is filled in the tip cap, suction is performed from the opening on the operation section side and pressure is applied from the tip cap side. Also,
For example, when filling the front end cap with the ultrasonic transmission medium, the insertion portion is heated.

The heating temperature of the ultrasonic transmission medium is, for example, 40 ° C. or higher. The heating temperature of the insertion portion is, for example, 40 ° C. or more. Further, the ultrasonic transmission medium,
For example, liquid paraffin, castor oil, olive oil, or mixtures thereof.

[0019]

According to the present invention, a heated ultrasonic transmission medium is filled in the distal end cap from the opening on the distal end cap side by performing suction from the opening on the operating section side. The viscosity of the ultrasonic transmission medium is reduced by heating.

Before filling the tip cap with the ultrasonic transmission medium, the ultrasonic transmission medium is defoamed while being heated.
By performing suction immediately after the defoaming, the ultrasonic transmission medium in which bubbles are extremely little dissolved is sealed.

Further, when the ultrasonic transmission medium is filled in the distal end cap, the inside of the distal end cap is pressurized by performing suction from the opening on the operation section side and applying pressure from the distal end cap side.

In addition, when the ultrasonic transmission medium is filled in the distal end cap, the temperature of the ultrasonic transmission medium is prevented from lowering by heating the insertion portion.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to a first embodiment of the present invention, FIG. 1 is an explanatory view showing a method of sealing an ultrasonic transmission medium, and FIG. 2 is a partial cross-sectional view showing a configuration of an ultrasonic endoscope. As shown in FIG. 2, an ultrasonic endoscope 1 to which the present embodiment is applied includes an elongated and flexible insertion section 2, and a large-diameter operation section connected to the rear end of the insertion section 2. Unit 3. The distal end of the insertion section 2 is provided with a rigid distal end component 5.

The distal end component 5 has a distal end body 6 and a distal end cap 7 provided on the distal end side of the distal end body 6. The distal end cap 7 is provided at its distal end with an opening 8 communicating with the inside of the distal end cap 7, and a plug 9 that fits into and closes the opening 8.

An ultrasonic probe 11 is provided in the tip cap 7. The ultrasonic probe 11 is attached to a shaft 12 rotatably supported by the distal end body 6 via a bearing. One end of a hollow flexible shaft 15 is connected to the shaft 12.
The flexible shaft 15 is inserted into the insertion section 2, and the other end is connected to a hard shaft 16 provided in the operation section 3. For example, a servo motor 17 is provided in the operation unit 3 as a rotation drive source, and a pulley 18 attached to a drive shaft of the servo motor 17 includes:
A belt 20 is wound around a pulley 19 attached to the hard shaft 16. The ultrasonic probe 11 is rotated by the servo motor 17 to perform a mechanical scan.

In the flexible shaft 15, one end of a signal cable (not shown) connected to the ultrasonic probe 11 is inserted. The other end of the signal cable is connected to an ultrasonic observation device (not shown). Then, the ultrasonic probe 11 emits an ultrasonic pulse in accordance with the drive pulse supplied from the ultrasonic observation device, and an echo of the ultrasonic pulse from the living body is received by the ultrasonic probe 11. You. The output signal of the ultrasonic probe 11 is subjected to signal processing by the ultrasonic observation device, and an ultrasonic image is displayed on a monitor.

A flexible tube 22 surrounding the flexible shaft 15 is provided in the insertion portion 2.
Is inserted. The distal end of the flexible tube 22 is fixed to the distal end body 6, and the rear end is connected to an oil reservoir 23 surrounding the connection between the flexible shaft 15 and the hard shaft 16. The hard shaft 16 passes through the rear end of the oil sump 23, and the outer periphery of the hard shaft 16 and the oil sump 2
3, a seal member 24 is provided.

The space between the flexible shaft 15 and the flexible tube 22 and the inside of the distal end cap 7 are filled with an ultrasonic transmission medium 30. The ultrasonic transmission medium 30 is, for example, liquid paraffin, castor oil, olive oil, or a mixture thereof. The ultrasonic transmission medium 30 also functions as an ultrasonic beam transmitter and a lubricant for the flexible shaft 15 and the flexible tube 22. And the ultrasonic transmission medium 3
The seal on the distal end side of 0 is performed by the plug 9 of the distal end cap 7, and the seal on the operation section 3 side is performed by the seal member 24.

From the oil reservoir 23, a connection tube 26 for connecting to a suction device 31 as shown in FIG. A base 27 is provided at an end of the connection tube 26, and a stopper 28 is attached to the base 27 by, for example, screwing.

Although not shown, the distal end portion 5 is provided with an observation window and an illumination window. An objective lens system is provided inside the observation window, and a distal end surface of an image guide is arranged at an image forming position of the objective lens system. This image guide is inserted through the insertion section 2,
It extends to an eyepiece provided at the rear end of the operation unit 3. The subject image formed by the objective lens system is transmitted to an eyepiece by an image guide, and is observed from the eyepiece.

It should be noted that instead of the image guide, CC
A solid-state imaging device such as D may be provided to display a subject image on a monitor. A light distribution lens is provided inside the illumination window. A light guide is continuously provided at the rear end of the light distribution lens. The light guide is inserted through the insertion section 2, the operation section 3, and a universal cord extending from the operation section 3, and is connected to a light source device (not shown).

Next, the ultrasonic endoscope 1 having the above configuration will be described.
In contrast, a method for sealing the ultrasonic transmission medium 30 and an apparatus for realizing the method will be described. As shown in FIG. 1, as an apparatus for realizing the sealing method, a container 40 for containing the ultrasonic transmission medium 30 is provided. A heating device 41 is integrally attached to the container 40, and the temperature can be adjusted by the heating device 41.

When the ultrasonic transmission medium 30 is sealed, the suction device 31 is connected to the base 27 of the connection tube 26 of the ultrasonic endoscope 1 via the connection base 33, the connection tube 34, and the switching cock 35. Connect.

Further, the degassing ultrasonic transmission medium 30 is put in the container 40. Then, the ultrasonic transmission medium 30 is heated by the heating device 41 to reduce
Heat above 0 ° C. In addition, the stopper 9 is removed from the opening 8 and the distal end component 5 is connected to the ultrasonic transmission medium 3 of the container 40.
Soak in 0.

Then, the ultrasonic transmission medium 30 is sucked into the distal end cap 7 and between the flexible shaft 15 and the flexible tube 22 by operating the suction device 31. At this time, the suction can be more smoothly performed by rotating the flexible shaft 15 by hand. That is, by rotating the flexible shaft 15, the air bubbles inside the flexible tube 22 easily flow toward the operation unit 3. After sufficient suction, the switching cock 35 is closed, the stopper 28 is attached to the mouthpiece 27, and the tip component 5 is connected to the container 40.
The ultrasonic transmission medium 30 is sealed by screwing a stopper 9 into the opening 8.

As described above, according to the present embodiment, since the viscosity of the ultrasonic transmission medium 30 is reduced by heating, the flow of the ultrasonic transmission medium 30 in the flexible tube 22 is improved, and The workability of sealing the transmission medium 30 is improved, and the work time can be reduced.

Also, by reducing the viscosity of the ultrasonic transmission medium 30, even if the clearance between the tip cap 7 and the ultrasonic probe is small, the escape of air bubbles is improved,
The tip cap 7 can be made smaller.

Also, even if the clearance between the flexible tube 22 and the flexible shaft 15 is small,
Air bubbles are well removed, and the time for sealing the ultrasonic transmission medium 30 does not become long. Therefore, the outer diameter of the insertion section 2 can be reduced.

In addition, the air bubbles inside the flexible shaft 15 are easily released, and the air bubbles do not come out of the tip cap 7 after the ultrasonic transmission medium 30 is sealed. In addition, the sealing operation can be performed efficiently and in a short time without increasing the suction force.

FIG. 3 is an explanatory view showing a method of sealing an ultrasonic transmission medium according to a second embodiment of the present invention. As a device for realizing the sealing method of the present embodiment, a defoaming container 50 in which a heating device 51 is integrally provided is newly provided. A vacuum pump 52 and a liquid sending pump 55 are connected to the defoaming container 50. The ultrasonic transmission medium 30 is contained in the defoaming container 50. Further, the discharge side of the liquid sending pump 55 is connected to the container 40 whose temperature can be adjusted by the heating device 41. Other configurations are the same as in the first embodiment.

In this embodiment, in the defoaming container 50, the ultrasonic transmission medium 30 is heated to 100 ° C. or higher by the heating device 51, and the defoaming is further promoted by the vacuum pump 52. Here, immediately after the defoaming is completed, the defoamed ultrasonic transmission medium 30 is transferred to the container 4 by the liquid feed pump 55.
Send to 0. Further, after the temperature is properly adjusted in the container 40,
As in the first embodiment, the ultrasonic transmission medium 30 is sucked from the opening 8 of the distal end cap 7 of the ultrasonic endoscope 1,
The inside of the tip cap 7 and between the flexible shaft 15 and the flexible tube 22 are sealed.

According to the present embodiment, the ultrasonic transmission medium 30
Is heated while defoaming, the defoaming effect is high, and the time from defoaming to sealing can be reduced, so that the dissolution of bubbles in the ultrasonic transmission medium 30 is extremely reduced, Even when the sonic endoscope 1 is used for a long time, air bubbles do not enter the distal end cap 7.

Other functions and effects are the same as those of the first embodiment. FIG. 4 is an explanatory view showing a method for sealing an ultrasonic transmission medium according to the third embodiment of the present invention.

The device for realizing the sealing method of this embodiment is the same as that of the second embodiment described above, except that a sealing member 57 is provided between the opening of the container 40 and the distal end component 5 of the ultrasonic endoscope 1. Is added.

In the present embodiment, when the ultrasonic transmission medium 30 is supplied into the container 40 by the liquid supply pump 55, the internal pressure of the container 40 increases due to the provision of the seal member 57, and the tip cap is closed. To the opening 8 of the ultrasonic transmission medium 30
Is pushed. At the same time, suction is performed by the suction unit 31 from the operation unit 3 side.

According to this embodiment, since the inside of the tip cap 7 and the inside of the flexible tube 22 are pressurized through the opening 8 of the tip cap 7, even if the suction force of the suction device 31 is increased, the flexible tube 22 is It is hard to be crushed, and the suction force can be increased. Accordingly, the sealing operation can be easily performed even with the ultrasonic transmission medium 30 having high viscosity.

Other functions and effects are the same as those of the above-described second embodiment. 5 and 6 relate to a fourth embodiment of the present invention, FIG. 5 is an explanatory view showing a method of sealing an ultrasonic transmission medium, and FIG. 6 is an enlarged view showing a cross section taken along line BB ′ of FIG. It is.

The present embodiment is different from the first to third embodiments in that a heating device 61 for the ultrasonic endoscope 1 is provided.
Is added. As shown in FIG. 6, the heating device 61 is provided with a notch 62 so as to be divided for attachment and detachment. This heating device 61 is, as shown in FIG.
The ultrasonic endoscope 1 is fixed to the outer periphery of the insertion section 2 by a peelable tape 63 such as a magic tape. Further, the heating device 61 has a temperature of 40 ° C. or more, for example, 70 ° C.
It is set to heat to ° C.

In this embodiment, while the ultrasonic endoscope 1 is heated to 70 ° C. by the ultrasonic endoscope heating device 61, the ultrasonic endoscope 1 is heated in the same manner as in the first to third embodiments. The sound transmission medium 30 is sealed.

According to the present embodiment, when the heated ultrasonic transmission medium 30 flows through the flexible tube 22, the temperature of the ultrasonic transmission medium 30 does not decrease, and the sealing can be performed more efficiently. Becomes

The heating temperature in the present invention is a temperature at which the viscosity (viscosity) of the ultrasonic transmission medium 30 becomes sufficiently small. As shown in FIG. 7, each ultrasonic transmission medium (liquid paraffin, castor oil, olive oil) is used. Etc.). In addition, the heat resistance of the flexible tube 22 and the tip cap 7,
The upper limit of the heating of the ultrasonic transmission medium 30 is determined by the heat resistance and the like of the ultrasonic endoscope 1 itself.

The present invention is not limited to the above embodiments. For example, the heating device 41 for heating the ultrasonic transmission medium 30 is not integrated with the container 40 but the ultrasonic transmission medium in the container 40. You may put in 30. Further, a container having a high heat retaining effect may be used as the container 40, and the heated ultrasonic transmission medium 30 may be put in the container 40.

Further, according to the present invention, an ultrasonic probe is fixed,
The present invention can also be applied to an ultrasonic endoscope that performs a mechanical scan by rotating an ultrasonic mirror. [Appendix] As described above, according to the present embodiment, the following embodiments can be obtained. That is, (1) an insertion section having an ultrasonic probe and a distal end cap covering the ultrasonic probe at a distal end, and an operating section provided at a rear end of the insertion section; And the operation unit side, respectively, in an ultrasonic endoscope provided with an opening communicating with the inside of the distal end cap, a method of sealing an ultrasonic transmission medium in the distal end cap,
The opening on the tip cap side is immersed in a heated ultrasonic transmission medium, suction is performed from the opening on the operation unit side, and the ultrasonic transmission medium is filled in the tip cap.
A method of sealing an ultrasonic transmission medium in an ultrasonic endoscope, comprising: (2) Before filling the tip transmission cap with the ultrasonic transmission medium, degassing is performed while heating the ultrasonic transmission medium,
The method for sealing an ultrasonic transmission medium in an ultrasonic endoscope according to the above (1), wherein suction is performed immediately after the defoaming to fill the distal end cap with an ultrasonic transmission medium. (3) When filling the tip end cap with the ultrasonic transmission medium, suction is performed from the opening on the operation unit side, and
The method for sealing an ultrasonic transmission medium in an ultrasonic endoscope according to the above (1), wherein pressure is applied from the end cap side. (4) The sealing of the ultrasonic transmission medium in the ultrasonic endoscope according to (1), wherein the insertion section is heated when filling the ultrasonic transmission medium into the distal end cap. Method. (5) The method for sealing an ultrasonic transmission medium in an ultrasonic endoscope according to (1), wherein a heating temperature of the ultrasonic transmission medium is set to 40 ° C. or higher. (6) The method for sealing an ultrasonic transmission medium in an ultrasonic endoscope according to (4), wherein a heating temperature of the insertion portion is set to 40 ° C. or higher. (7) The method for sealing an ultrasonic transmission medium in an ultrasonic endoscope according to (1), wherein the ultrasonic transmission medium is liquid paraffin, castor oil, olive oil, or a mixture thereof. .

[0054]

As described above, according to the present invention, since the ultrasonic transmission medium is heated to lower the viscosity and then sucked, the sealing operation of the ultrasonic transmission medium can be improved.
There is an effect that bubbles are well removed and the number of bubbles after sealing is reduced.

Before filling the tip cap with the ultrasonic transmission medium, the ultrasonic transmission medium is defoamed while being heated.
By performing suction immediately after the defoaming, the defoaming effect is high, the dissolution of bubbles in the ultrasonic transmission medium is extremely reduced, and even if the ultrasonic endoscope is used for a long time, bubbles are mixed into the tip cap. This has the effect of reducing

Also, when filling the ultrasonic transmission medium into the distal end cap, the inside of the distal end cap is pressurized by performing suction from the opening on the operation section side and applying pressure from the distal end cap side. This has the effect that the suction force can be increased and the sealing operation can be easily performed even with a highly viscous ultrasonic transmission medium.

Further, when filling the ultrasonic transmission medium into the tip cap, by heating the insertion portion, it is possible to prevent the temperature of the ultrasonic transmission medium from decreasing during the sealing operation.
There is an effect that sealing can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a method for sealing an ultrasonic transmission medium according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating a configuration of an ultrasonic endoscope according to the first embodiment of the present invention.

FIG. 3 is an explanatory view showing a method for sealing an ultrasonic transmission medium according to a second embodiment of the present invention.

FIG. 4 is an explanatory view showing a method for sealing an ultrasonic transmission medium according to a third embodiment of the present invention.

FIG. 5 is an explanatory view showing a method for sealing an ultrasonic transmission medium according to a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an enlarged cross section taken along line BB ′ in FIG. 5;

FIG. 7 is a table showing a relationship between temperature and viscosity of an ultrasonic transmission medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic endoscope 2 ... Insertion part 3 ... Operation part 5 ... Tip construction part 7 ... Tip cap 8 ... Opening 11 ... Ultrasonic probe 15 ... Flexible shaft 22 ... Flexible tube 30 ... Ultrasonic transmission medium 31 ... Suction device 40 ... Container 41 ... Heating device

Claims (3)

[Claims] 1. An insertion unit having an ultrasonic probe at a distal end thereof and a distal end cap covering the ultrasonic probe, and an operating unit provided at a rear end of the insertion unit, wherein the distal end cap is provided. And the operation unit side, respectively, in an ultrasonic endoscope provided with an opening communicating with the inside of the distal end cap,
A method of sealing an ultrasonic transmission medium in the tip cap, wherein the opening on the tip cap side is immersed in a heated ultrasonic transmission medium, and suction is performed from the opening on the operation unit side. Filling the distal end cap with an ultrasonic transmission medium. A method of sealing an ultrasonic transmission medium in an ultrasonic endoscope, comprising: 2. Before filling the tip transmission cap with the ultrasonic transmission medium, the ultrasonic transmission medium is defoamed while being heated. Immediately after the defoaming, suction is applied to the inside of the tip cap. 2. The method for sealing an ultrasonic transmission medium in an ultrasonic endoscope according to claim 1, wherein the ultrasonic transmission medium is filled with the ultrasonic transmission medium. 3. The method according to claim 1, wherein when the ultrasonic transmission medium is filled in the tip cap, suction is performed from an opening on the operation section side and pressure is applied from the tip cap side. A method for sealing an ultrasonic transmission medium in an ultrasonic endoscope according to the present invention.