JP2013048933A - Ultrasonic endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic endoscope equipped with an ultrasonic probe to improve insertability into a body cavity by reducing a distal end rigid length.SOLUTION: The ultrasonic endoscope has the ultrasonic probe 12 which is provided at the distal end side of a distal end hard section 2a that constitutes the distal end section out of a flexible tube section and a bend section and the distal end rigid portion 2a constituting an insertion section, and a treatment instrument outlet 24 which is a hole 27 used for treatment and formed in the distal end rigid portion 2a. The ultrasonic probe 12 is made up of ultrasonic vibrators 9 arranged in a convex, circular arc shape. The center of curvature of the plurality of ultrasonic vibrators 9 is disposed closer to the proximal end side than the treatment instrument outlet 24.

Description

  The present invention relates to a convex probe ultrasonic endoscope in which an observation optical system, a treatment instrument outlet, and a plurality of ultrasonic transducers are arranged at the distal end of an insertion portion of an endoscope.

  2. Description of the Related Art An ultrasonic endoscope having a convex ultrasonic probe at the tip of an endoscope is known as an endoscope that performs ultrasonic treatment in a body cavity or treatment and treatment using treatment tools. Yes. The convex ultrasonic probe is configured by arranging a plurality of ultrasonic transducers in a convex arc shape.

  As an ultrasonic endoscope having a convex-type ultrasonic probe, for example, Patent Document 1 and Patent Document 2 (see FIG. 19) are shown. In these ultrasonic endoscopes, an observation optical system is provided at the distal end hard portion in the vicinity of the ultrasonic probe, and the observation optical system has an optical axis in the front perspective direction.

  In an ultrasonic endoscope, a positional relationship for observing the inside of an observation site as an ultrasonic tomographic image while visually recognizing with an observation optical system is essential. In order to confirm the insertion depth of the treatment tool from the ultrasonic tomographic image, an ultrasonic scanning range in consideration of the operation range of the treatment tool is necessary.

  Therefore, as shown in Patent Documents 1 and 2, when the observation optical system is a front perspective, by providing an ultrasonic probe on the distal end side of the distal rigid portion, the optical axis of the front perspective and the operation range of the treatment tool Can be accommodated within the ultrasonic scanning range.

JP-A-8-131442 JP 2004-350700 A

  However, in the ultrasonic endoscope described in Patent Document 1, the structure including the ultrasonic probe in addition to the distal end rigid portion is a hard length of a so-called endoscope insertion portion. For this reason, compared with the normal endoscope which is not equipped with an ultrasonic probe, the distal end rigid length is longer in the ultrasonic endoscope. Thus, skilled techniques are required for inserting the ultrasonic endoscope into the body cavity.

  In the structure described in Patent Document 2, a slope is provided on the hard tip portion, and an ultrasonic probe is mounted on the slope. For this reason, the distal end hard length is shorter than that of the ultrasonic endoscope described in Patent Document 1. However, a semicircular ultrasonic probe having an ultrasonic scanning range of 180 degrees is provided in order to allow the therapeutic instrument derived from the treatment instrument outlet to be within the ultrasonic scanning range. Therefore, in addition to the distal end rigid portion, a structure including a length twice as long as the radius of curvature of the ultrasonic probe is the distal end rigid length. As a result, since the distal end rigid length of the ultrasonic endoscope is longer than that of a normal endoscope, a skillful technique is required for inserting the ultrasonic endoscope into the body cavity.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an ultrasonic endoscope including an ultrasonic probe that shortens the distal end rigid length and improves insertion into a body cavity. I have to.

  An ultrasonic endoscope according to an aspect of the present invention includes a distal rigid portion to be inserted into a subject, a distal end surface of the distal rigid portion, a treatment instrument insertion channel disposed in the distal rigid portion, and the treatment. An opening on the distal end side of the instrument insertion channel, and a treatment instrument outlet port disposed on the distal end surface and a treatment instrument derived from the treatment instrument outlet port on the distal end surface is disposed at an observable position And a plurality of ultrasonic transducers arranged in a convex arc shape so that the center of curvature is on the base end side with respect to the treatment instrument outlet.

  According to this configuration, the centers of curvature of the plurality of ultrasonic transducers are retracted from the proximal end side of the treatment instrument outlet, that is, from the treatment instrument outlet. Therefore, the maximum protruding amount from the treatment instrument outlet of the ultrasonic probe toward the distal end is less than the radial dimension.

  ADVANTAGE OF THE INVENTION According to this invention, the ultrasonic endoscope provided with the ultrasonic probe which shortens a front-end | tip hard length and improves the insertion property in a body cavity is realizable.

The figure explaining the structure of an ultrasonic endoscope The perspective view explaining the structure of the front-end | tip part of an ultrasonic endoscope The front view which looked at the front-end | tip part shown in FIG. 2 from the front AA line sectional view of FIG. The figure explaining the relationship between the ultrasonic probe comprised by arranging a plurality of ultrasonic transducers, the ultrasonic observation region of the ultrasonic probe, and the treatment instrument derived from the treatment instrument outlet Figure showing an example of an ultrasound image with artifacts The figure which shows the example of an ultrasonic image drawn with the ultrasonic probe shown in FIG. The figure explaining the relationship between the tissue contact surface of the nosepiece and the acoustic lens surface of the ultrasonic probe Diagram explaining the presence of a lesion near the boundary of the ultrasound observation area of an ultrasound endoscope The figure which shows the ultrasonic image in the observation state shown in FIG. Front view of the tip with an ultrasonic probe with continuously changing elevation width as seen from the front BB sectional view of FIG. Front view of a front end portion including an ultrasonic probe provided with a portion in which a part of the elevation width changes continuously. It is CC sectional view taken on the line of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 14 relate to an embodiment of the present invention, FIG. 1 is a diagram for explaining the configuration of an ultrasonic endoscope, and FIG. 2 is a perspective view for explaining the configuration of a distal end portion of the ultrasonic endoscope. 3 is a front view of the tip shown in FIG. 2 as viewed from the front, FIG. 4 is a cross-sectional view taken along line AA of FIG. 3, and FIG. 5 is an ultrasonic probe configured by arranging a plurality of ultrasonic transducers. FIG. 6 is a diagram for explaining the relationship between the ultrasound observation region of the ultrasound probe and the treatment instrument derived from the treatment instrument outlet, FIG. 6 is a diagram showing an example of an ultrasound image in which artifacts appear, and FIG. FIG. 8 is a diagram showing an example of an ultrasound image drawn by the ultrasound probe shown in FIG. 5, FIG. 8 is a diagram for explaining the relationship between the tissue contact surface of the nosepiece and the acoustic lens surface of the ultrasound probe, 9 is a diagram for explaining a state in which a lesion exists near the boundary of the ultrasonic observation region of the ultrasonic endoscope, and FIG. 10 is an ultrasonic image in the observation state shown in FIG. FIG. 11 is a front view of a front end portion provided with an ultrasonic probe whose elevation width continuously changes, as viewed from the front, FIG. 12 is a sectional view taken along line BB in FIG. 11, and FIG. FIG. 14 is a cross-sectional view taken along the line CC of FIG. 13, and FIG. 14 is a cross-sectional view taken along the line CC in FIG. 13.

  As shown in FIG. 1, an ultrasonic endoscope (hereinafter also referred to as an endoscope) 1 according to the present embodiment is provided at an elongated insertion portion 2 to be inserted into a body cavity and a proximal end of the insertion portion 2. And the universal cord 4 extending from the side portion of the operation unit 3. An endoscope connector 5 is provided at the other end of the universal cord 4. An ultrasonic cable 6 extends from the side of the endoscope connector 5. An ultrasonic connector 7 is provided at the other end of the ultrasonic cable 6.

The insertion portion 2 has a distal end rigid portion 2a formed of a hard member in order from the distal end side, a bending portion 2b configured to be bendable, and a long length from the proximal end of the bending portion 2b to the distal end of the operation portion 3. The flexible tube portion 2c having flexibility is configured to be connected.
The operation unit 3 is provided with an angle knob 3a for performing a bending operation. Further, the operation unit 3 is provided with an air / water supply button 3b for performing air supply and water supply operations, and a suction button 3c for performing suction. Further, the operation unit 3 is provided with a treatment instrument insertion port 3d for guiding the treatment instrument into the body cavity.

  Reference numeral 10 denotes an ultrasonic unit comprising an ultrasonic probe having a convex type ultrasonic scanning surface. The ultrasonic unit 10 forms an ultrasonic scanning range 10A that scans the front direction with respect to the endoscope insertion axis direction.

  As shown in FIGS. 2 and 3, the distal end rigid portion 2 a of the insertion portion 2 is provided with an ultrasound unit 10 for obtaining acoustic image information by ultrasound. The ultrasonic unit 10 includes a nose piece 11 that is a casing and an ultrasonic probe 12. The ultrasonic probe 12 is integrally disposed in a notch formed at a substantially central portion of the nosepiece 11. As shown in this figure, the tissue contact surface 11a constituting the nosepiece 11 and the acoustic lens surface 12a of the ultrasonic probe 12 are configured to protrude from the distal end surface 21 of the distal rigid portion 2a. .

  As shown in FIGS. 4 and 5, the ultrasonic probe 12 includes, for example, a plurality of ultrasonic transducers 9 and an acoustic lens 12a. The plurality of ultrasonic transducers 9 are arranged so as to form a convex arc.

  On the other hand, on the distal end surface 21 of the distal rigid portion 2a, as shown in FIGS. 2 and 3, an observation window 22a constituting the observation optical system 22, an illumination window 23a constituting the illumination optical system 23, a puncture needle, etc. A treatment instrument outlet 24 from which the treatment instrument is derived, an air / water supply nozzle 25 that ejects fluid such as water and air toward the observation window 22a, and a sub-water supply channel 26 for supplying water forward. Is provided. Instead of providing the auxiliary water supply channel port 26, the auxiliary water supply channel port 26 may be configured as a second treatment instrument outlet.

  The central axis of the treatment instrument outlet 24 is the center of the ultrasonic probe 12 so that the treatment instrument derived from the treatment instrument outlet 24 is within the ultrasonic scanning range 10A obtained by the ultrasonic probe 12. They are arranged on the same straight line as the line L2.

  The observation window 22a, the illumination window 23a, and the air / water supply nozzle 25 are arranged together, for example, on the right side in the figure with respect to the treatment instrument outlet 24, and are arranged outside the ultrasonic scanning range 10A. In the observation window 22a, the arrangement position of the air / water supply nozzle 25 among the illumination window 23a and the air / water supply nozzle 25 is set to be a position farthest from the ultrasonic observation region 10A. Further, in the present embodiment, the arrangement positions of the illumination window 23a, the observation window 22a, and the air / water supply nozzle 25 are improved in observation performance, improvement in washability, and reduction in the outer diameter of the endoscope distal end. In consideration of the purpose to be achieved, they are arranged in a straight line.

  The observation window 22a has an observation visual field range of the observation optical system 22 (see the range of reference numeral 22A indicated by a one-dot chain line in FIG. 4). The illumination window 23a has an illumination light irradiation range of the illumination optical system 23 (see the range of reference numeral 23A indicated by a two-dot chain line in FIG. 4). The observation visual field range 22A and the illumination light irradiation range 23A are configured so that the ultrasonic probe 12 is not included in the range.

  Note that the observation window 22a and the illumination window 23a are provided in the observation portion distal end surface 21a configured to slightly protrude from the distal end surface 21. Further, the auxiliary water supply channel port 26 is the other surface side opposite to the one surface side across the treatment instrument outlet port 24 where the observation window 22a, the illumination window 23a, and the air / water supply nozzle 25 are arranged, It is arranged outside the ultrasonic scanning range 10A. When this sub-water supply channel port 26 is configured as the second treatment instrument outlet, the diameter size is set in accordance with the treatment tool that uses the channel diameter.

  This makes it possible to perform a procedure using two treatment tools under endoscopic observation. For this reason, a treatment tool that protrudes from the second treatment tool outlet and is used under endoscopic observation, and a treatment tool that protrudes from the treatment tool outlet 24 and is used under ultrasonic diagnosis are combined efficiently. , A configuration for performing diagnosis and treatment becomes possible.

  As shown in FIG. 4, a distal bending piece 8a constituting the bending portion 2b is connected and fixed to the proximal end side of the distal rigid portion 2a. A plurality of bending pieces (not shown) are connected to the distal bending piece 8a. A straight line connecting the centers of the bending portions 2b formed by connecting these bending pieces is the endoscope insertion axis L1.

  At the predetermined position of the distal bending piece 8a, the distal ends of the bending wires 8w for up, down, left and right are fixed. Therefore, when the surgeon appropriately operates the angle knob 3a, the bending wire 8w corresponding to the operation is pulled and loosened, and the bending portion 2b is bent. The plurality of bending pieces are covered with a bending rubber 8g. The distal end portion of the curved rubber 8g is integrally fixed by a bobbin adhering portion 8h provided on the distal end hard portion 2a.

  The distal end surface 21 of the distal end rigid portion 2a and the distal end surface 21a for the observation unit are configured to be orthogonal to the endoscope insertion axis L1. A treatment instrument insertion channel hole (hereinafter, abbreviated as a treatment instrument hole) 27 and an arrangement hole 30 that constitute the treatment instrument outlet 24 are formed in the distal end rigid portion 2a.

  In addition to the holes 27 and 30, the distal end rigid portion 2a is ejected from a through hole provided with an observation optical system, a through hole provided with an illumination optical system, and an air / water supply nozzle 25. Are provided with a through hole for supplying air and water, a through hole constituting the auxiliary water supply channel port 26, and the like.

  The central axis L4 in the longitudinal direction of the treatment instrument hole 27 is formed substantially parallel to the endoscope insertion axis L1. A central axis L5 in the longitudinal direction of the arrangement hole 30 is formed substantially parallel to the endoscope insertion axis L1. In addition, the optical axis L6 of the observation optical system provided in the ultrasonic endoscope 1 and the optical axis L7 of the illumination optical system are also parallel to the endoscope insertion axis L1.

  Therefore, the observation optical system provided in the ultrasonic endoscope 1 of the present embodiment is a so-called direct-view type in which the observation visual field is set to the front front, in other words, the insertion direction that is the front side of the endoscope insertion axis L1. It is.

  One end of a tube connection pipe 28 that is inclined by a predetermined amount is communicated with the proximal end side of the treatment instrument hole 27. In the tube connection pipe 28, one end portion of the channel tube 29 constituting the treatment instrument insertion channel is communicated with the other end portion. The other end of the channel tube 29 communicates with the treatment instrument insertion port 3d.

  Then, the treatment instrument inserted through the treatment instrument insertion port 3 d smoothly moves through the channel tube 29, the tube connection pipe 28, and the treatment instrument hole 27 and is led out from the treatment instrument outlet port 24. The treatment tool led out from the treatment tool lead-out port 24 is led out parallel to the endoscope insertion axis L1 toward the front which is the insertion direction of the insertion portion 2.

  That is, in the state where the distal end portion of the puncture needle is disposed as the treatment instrument in the treatment instrument hole 27, for example, the needle tube constituting the puncture needle is protruded. Then, the needle tube protrudes from the treatment instrument outlet 24 toward the front front side that is observed through the observation window 22a substantially parallel to the endoscope insertion axis L1.

  On the other hand, the arrangement | positioning hole 30 is provided in the front-end | tip hard part 2a. The ultrasonic unit 10 is fitted into the arrangement hole 30, and the contact surface of the nosepiece 11 and the abutting surface 36 of the distal end hard portion 2a are in contact with each other, thereby positioning the ultrasonic unit 10 with respect to the arrangement hole 30. Is called. An ultrasonic cable 34 connected to the ultrasonic probe 12 is led out from the other end side of the ultrasonic unit 10.

  The outer shape (surface 11b in FIG. 2) from the abutting surface 36 of the distal end rigid portion 2a to the distal end includes the elevation width W of the ultrasonic probe 12 and the contact surface 11a, and is shown in FIG. Thus, it is set to be substantially the same size as the tip outer dimension of the tip rigid portion 2a.

  Therefore, when the ultrasonic unit 10 is pressed against the body tissue during ultrasonic observation, the ability of the operator holding the operation unit 3 in the direction of the endoscope insertion axis L1 is reliably transmitted to the ultrasonic unit 10. Is done. As a result, as shown in FIG. 8, the tissue contact surface 11a and the acoustic lens surface 12a can be brought into close contact with the body tissue substantially uniformly. In this way, a good ultrasonic observation image can be obtained by pressing the tissue contact surface 11a and the acoustic lens surface 12a of the ultrasonic unit 10 against the body tissue in a stable state.

  The ultrasonic probe 12 shown in FIGS. 4 and 5 is configured by arranging a plurality of ultrasonic transducers 9 in which, for example, a backing material, a piezoelectric transducer, a matching layer, and an acoustic lens are stacked. The plurality of ultrasonic transducers 9 are arranged most proximally with respect to the treatment instrument protruding port, and the final ultrasonic wave farthest from the first ultrasonic transducer 9F that emits an ultrasonic wave is counted from the treatment tool protruding port. The transducers 9L are arranged at a predetermined interval p. Then, as shown in FIG. 5, the center of curvature O1 of the arc of the ultrasound probe 12 is configured to be located closer to the base end side than the opening surface 24a of the treatment instrument outlet 24 provided in the distal end rigid portion 2a. Has been. The ultrasonic transducer 9 may be a MUT (Micromachined Ultrasound Transducer) element instead of a piezoelectric element.

  Thus, by providing the center of curvature O1 of the arc of the ultrasound probe 12 on the proximal side from the opening surface 24a of the treatment instrument outlet 24, the distal end hard length of the endoscope 1 is shortened. For this reason, the insertion property of the endoscope into the body cavity is improved. Further, since the ultrasonic probe 12 is not arranged within the observation visual field range of the endoscope 1, the problem that a part of the endoscopic image is lost by the ultrasonic probe 12 is solved. Furthermore, since the ultrasonic probe 12 does not enter the illumination light irradiation range of the endoscope 1, a part of the illumination light is not blocked by the ultrasonic probe 12 and the observation of the endoscope 1 is performed. Illumination light spreads within the field of view and a good endoscopic image can be obtained.

  In the ultrasonic probe 12, the direction of the central axis LF of the sound ray of the first ultrasonic transducer 9F is set to the distal end surface 21 of the distal rigid portion 2a (specifically, the distal end surface 21 including the treatment instrument outlet 24). Is set to be inclined toward the tip side by an angle θ1 with respect to the tip surface 21.

  Further, when the direction of the central axis LF of the sound ray of the first ultrasonic transducer 9F is set to be inclined by the angle θ1, the directivity angle θ2 of the first ultrasonic transducer 9F is taken into consideration. Specifically, at least a part of the tip rigid portion 2a made of a material capable of reflecting ultrasonic waves within a directivity angle surrounded by a two-dot chain line in FIG. 5, for example, metal or hard resin, or an air / water supply nozzle 25. The angle θ1 is set so that at least a part of the angle does not enter. The angle θ1 is set to be larger than at least half of the directivity angle θ2.

  When the distal end rigid portion 2a is within the directivity angle range, an artifact 42 as shown in FIG. 6 appears. However, according to the configuration of the present embodiment, no artifact appears, and the treatment instrument ultrasonic image 41a is clearly depicted in the ultrasonic image 40 as shown in FIG. That is, the treatment instrument ultrasonic image 41 a from the state where the treatment instrument 41 is slightly protruded from the treatment instrument outlet 24 until the treatment instrument 41 is punctured into the lesioned part 43 is clearly depicted in the ultrasound image 40. The Such good visibility can be obtained, and the treatment instrument 41 can be accurately introduced into the lesioned part 43.

  On the other hand, the direction of the central axis LL of the sound ray of the final ultrasonic transducer 9L is set so as to expand in parallel with the endoscope insertion axis L1 or as it goes forward by an angle θ3.

  As a result, when the treatment instrument 41 projecting from the treatment instrument outlet 24 is projected forward in a direction substantially parallel to the endoscope insertion axis L1, the treatment instrument 41 is near the center of the ultrasonic scanning range 10A. Keep moving. Further, even when the endoscope 1 has moved before puncturing due to pulsation or the like and the lesioned part 43 exists outside the endoscope insertion axis L1 as shown in FIG. When the lesioned part 43 is positioned at the edge of the acoustic scanning range 10A, the lesioned part 43 is displayed at the edge in the ultrasonic image 40 as shown in FIG.

  That is, even when the relative position between the endoscope 1 and the lesioned part 43 is deviated, the ultrasound scanning range 10A exists up to an angle exceeding the endoscope insertion axis L1, and thus the lesioned part 43 is lost. It is prevented. Therefore, the operator can easily correct the positional deviation between the endoscope 1 and the lesioned part 43 by performing a hand operation. Thereafter, the treatment tool 41 is introduced into the lesioned part 43.

  In the embodiment described above, the elevation width of the ultrasonic probe 12 is set with the dimension W as shown in FIG. In other words, the elevation width of the plurality of ultrasonic transducers 9 constituting the ultrasonic probe 12 is unified with the dimension W. On the other hand, in the ultrasonic probe 12A having the configuration shown in FIGS. 11 and 12, the elevation width WF of the first ultrasonic transducer 9F and the elevation width WL of the final ultrasonic transducer 9L are different dimensions. It is set to.

  Specifically, the elevation width of the ultrasonic transducer 9 gradually increases from the first ultrasonic transducer 9F toward the final ultrasonic transducer 9L, that is, from A to B in FIG. ) Is a narrow setting. Therefore, as shown in FIG. 11, the ultrasonic probe 12A is smaller than the ultrasonic probe 12 shown in FIG. 3 indicated by a two-dot chain line, and is formed in a trapezoidal shape when viewed from the front.

  In the ultrasonic unit 10A that constitutes the ultrasonic probe 12A as described above, in principle, the emitted ultrasonic beam becomes more easily diffused and the sensitivity decreases as the elevation width becomes narrower. To do. However, in the present embodiment, the shape of the nosepiece 11A is set to be small in accordance with the change in the elevation width of the ultrasonic probe 12A.

  Accordingly, the nose piece 11A is smaller than the outer shape of the nose piece 11 shown in FIG. 3 shown by the two-dot chain line, and the diameter of the distal end portion of the endoscope 1 can be reduced. As a result, the insertion property of the endoscope can be improved.

  In the ultrasonic probe 12B having the configuration shown in FIGS. 13 and 14, the first ultrasonic transducer 9F to the nth ultrasonic transducer 9n are set to the same size. That is, the elevation width in the range from C to D in FIG. In contrast, the (n + 1) th ultrasonic transducer 9 (n + 1) and the final ultrasonic transducer 9L have different elevation widths. Specifically, the elevation width of the ultrasonic transducer 9 from the (n + 1) th ultrasonic transducer 9 (n + 1) to the final ultrasonic transducer 9L, that is, from E to F in FIG. Is a setting that gradually becomes narrower. Therefore, as shown in FIG. 13, the ultrasonic probe 12B is smaller than the ultrasonic probe 12 shown in FIG. 3 shown by a two-dot chain line, and is formed into a home base shape when viewed from the front.

This makes it possible to reduce the diameter of the distal end portion of the endoscope 1 by making the nose piece 11B smaller than the outer shape of the nose piece 11 shown in FIG. Further, in the ultrasonic unit 10B constituting the ultrasonic probe 12B, the elevation width is the same dimension in the range of the elevation width from A to B. Therefore, an ultrasonic image having the same image quality as that of the ultrasonic unit 10 is used. Can be obtained.
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 ... Ultrasound endoscope 2a ... Tip rigid part 9, 9F, 9L ... Ultrasonic transducer 10 ... Ultrasonic unit 10A ... Ultrasound scanning range 11 ... Nose piece 11a ... Tissue contact surface 12 ... Ultrasonic probe Child 12a ... Acoustic lens surface 21 ... Tip surface 22 ... Observation optical system 22a ... Observation window 22A ... Observation field range 23 ... Illumination optical system 23a ... Illumination window 23A ... Illumination light irradiation range 24 ... Treatment instrument outlet 25 ... Air supply / water supply Nozzle 27 ... treatment tool hole 41 ... treatment tool

Claims (7)

A distal rigid portion to be inserted into the subject;
A distal end surface of the distal rigid portion;
A treatment instrument insertion channel disposed in the distal rigid portion;
An opening on the distal end side of the treatment instrument insertion channel, and a treatment instrument outlet port disposed on the distal end surface;
Arranged in a convex arcuate shape so that the treatment instrument derived from the treatment instrument outlet is observable on the distal end surface, and the center of curvature is on the proximal side of the treatment instrument outlet A plurality of ultrasonic transducers,
An ultrasonic endoscope comprising:   The ultrasonic endoscope according to claim 1, wherein a central axis in a longitudinal direction of the treatment instrument insertion channel is set in parallel to an endoscope insertion axis.   The ultrasonic endoscope according to claim 1, wherein the distal end surface is perpendicular to an endoscope insertion axis.   The central axis of the sound ray of the first ultrasonic transducer disposed on the most proximal side among the plurality of ultrasonic transducers is more than the line passing through the center of curvature and perpendicular to the endoscope insertion axis. The ultrasonic endoscope according to claim 1, wherein the ultrasonic endoscope is set to be inclined in a distal direction. The relationship between the angle θ1 formed by the central axis of the sound ray of the first ultrasonic transducer and the tip surface, and the directivity angle θ2 of the ultrasonic wave radiated from the first ultrasonic transducer, At least θ1> θ2 / 2
The ultrasonic endoscope according to claim 4, wherein:   The central axis of the sound ray of the final ultrasonic transducer farthest from the first ultrasonic transducer arranged on the most proximal side among the plurality of ultrasonic transducers is set to the endoscope insertion axis. The ultrasonic endoscope according to claim 1, wherein the ultrasonic endoscope is set in parallel. When the plurality of ultrasonic transducers form an arc shape, the final ultrasonic transducer farthest from the first ultrasonic transducer arranged on the most proximal side passes through the center of curvature. Place the ultrasonic transducer until it crosses the line parallel to the endoscope insertion axis,
The ultrasonic endoscope according to claim 1, wherein a central axis of a sound ray of the final ultrasonic transducer is set to intersect with the endoscope insertion axis.

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