Patent Publication Number: US-2018042587-A1

Title: Biopsy needle

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of PCT international application Ser. No. PCT/JP2016/065761, filed on May 27, 2016 which designates the United States, incorporated herein by reference, and which claims the benefit of priority from Japanese Patent Application No. 2015-117605, filed on Jun. 10, 2015, incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a biopsy needle for collecting body tissues. 
     2. Related Art 
     Conventionally, biopsy for collecting body tissues is performed for a pathological diagnostic confirmation by puncturing lesion tissue by introducing an elongated biopsy needle to an observed region through a channel for treatment tools for an ultrasound endoscope, using ultrasonic tomogram obtained by an ultrasound endoscope being used as a guide. As a biopsy needle, there is a proposed configuration in which an inner needle having a cutout (notch) for tissue collection formed on a distal end-side side surface is arranged inside a hollow outer needle and the inner needle and the outer needle are configured to advance or retreat by a moving mechanism (for example, refer to WO 2007/110812). In the biopsy, puncture is performed with the biopsy needle to reach the tissue of the biopsy site in a state where the outer needle of the biopsy needle substantially covers the notch of the inner needle, and thereafter, the inner needle is allowed to protrude from the distal end of the outer needle until the notch is exposed. This causes the body tissue to enter the inside of the notch, and thus, while the body tissue that has entered the inside of the notch is cut with the distal end of the outer needle by allowing the outer needle to advance, the notch is covered with the outer needle with the body tissue caught inside the notch. In this state, the biopsy needle is pulled out from the biopsy site, and thereafter, the notch is exposed by retreating the outer needle, and the body tissue inside the notch is collected. 
     SUMMARY 
     In some embodiments, a biopsy needle includes an outer needle being tubular and having a first needle tip at one end of the outer needle in a longitudinal direction, and an inner needle having a pillar shape and configured to be inserted into and movable in the outer needle in the longitudinal direction of the outer needle. The inner needle includes: a distal end portion having a second needle tip at a distal end of the inner needle and having an inclined surface inclined toward the second needle tip at the distal end; a notch portion having a notch on a side surface closer to a proximal end side of the inner needle than the inclined surface to collect body tissues; and a guide portion leading from the distal end portion to the notch portion. 
     The above and other features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram for illustrating a distal end section of a biopsy needle according to a first embodiment; 
         FIG. 2  is a cross-sectional view taken along line A-A in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view taken along line B-B in  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of the distal end section of the biopsy needle illustrated in  FIG. 1  after the body tissue collection, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction and the center of the needle tip of an inner needle; 
         FIG. 5  is a diagram for illustrating a biopsy method implemented by the biopsy needle illustrated in  FIG. 1 ; 
         FIG. 6  is a diagram for illustrating a distal end section of a biopsy needle according to a conventional technique; 
         FIG. 7  is a cross-sectional view taken along line C-C in  FIG. 6 ; 
         FIG. 8  is a cross-sectional view of the distal end section of the biopsy needle according to the conventional technique after the body tissue is collected, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction and the center of the needle tip of the inner needle; 
         FIG. 9  is a cross-sectional view of the distal end section of the biopsy needle according to the conventional technique after the body tissue is collected, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction and the center of the needle tip of the inner needle; 
         FIG. 10  is a cross-sectional view of the distal end section of the biopsy needle according to the conventional technique after the body tissue is collected, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction and the center of the needle tip of the inner needle; 
         FIG. 11  is a cross-sectional view of the biopsy needle according to the first embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction and the center of the needle tip of the inner needle; 
         FIG. 12  is a diagram illustrating a first state and a second state of the biopsy needle illustrated in  FIG. 1 ; 
         FIG. 13  is a diagram illustrating protruding operation of the outer needle and the inner needle in the biopsy needle illustrated in  FIG. 1 ; 
         FIG. 14A  is a diagram illustrating biopsy operation of the biopsy needle illustrated in  FIG. 11 ; 
         FIG. 14B  is a diagram illustrating biopsy operation of the biopsy needle illustrated in  FIG. 11 ; 
         FIG. 14C  is a diagram illustrating biopsy operation of the biopsy needle illustrated in  FIG. 11 ; 
         FIG. 14D  is a diagram illustrating biopsy operation of the biopsy needle illustrated in  FIG. 11 ; 
         FIG. 14E  is a diagram illustrating biopsy operation of the biopsy needle illustrated in  FIG. 11 ; 
         FIG. 14F  is a diagram illustrating biopsy operation of the biopsy needle illustrated in  FIG. 11 ; 
         FIG. 15  is a cross-sectional view of a distal end section of a biopsy needle according to a first modification of the first embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction; 
         FIG. 16  is a cross-sectional view taken along line D-D in  FIG. 15 ; 
         FIG. 17  is a plan view of a distal end section of a biopsy needle according to a second modification of the first embodiment; 
         FIG. 18  is a cross-sectional view of a distal end section of a biopsy needle according to the second modification of the first embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction; 
         FIG. 19  is a diagram for illustrating a distal end section of a biopsy needle according to a second embodiment; 
         FIG. 20  is a cross-sectional view of the distal end section of the biopsy needle according to the second embodiment after body tissue collection, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction; 
         FIG. 21  is a diagram for illustrating a distal end section of a biopsy needle according to a first modification of the second embodiment; 
         FIG. 22  is a perspective view of a distal end portion of the inner needle illustrated in  FIG. 21 ; 
         FIG. 23  is a cross-sectional view taken along line E-E in  FIG. 21 ; 
         FIG. 24  is a plan view of a distal end section of another biopsy needle according to the first modification of the second embodiment; 
         FIG. 25  is a diagram for illustrating a distal end section of a biopsy needle according to a second modification of the second embodiment; 
         FIG. 26  is a schematic view illustrating another example of the distal end section of the biopsy needle according to the second modification of the second embodiment; 
         FIG. 27  is a cross-sectional view taken along line F-F in  FIG. 26 ; 
         FIG. 28  is a schematic view illustrating another example of the distal end section of the biopsy needle according to the second modification of the second embodiment; 
         FIG. 29  is a cross-sectional view of a distal end section of a biopsy needle according to a third embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction; 
         FIG. 30  is a cross-sectional view taken along line G-G in  FIG. 29 ; 
         FIG. 31  is a cross-sectional view of a distal end section of a biopsy needle according to a first modification of the third embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction; 
         FIG. 32  is a cross-sectional view taken along line H-H in  FIG. 31 ; 
         FIG. 33  is a side view of a distal end section of an inner needle according to a second modification of the third embodiment; 
         FIG. 34  is a perspective view of the distal end section of the inner needle illustrated in  FIG. 33 ; 
         FIG. 35  is a cross-sectional view taken along line I-I in  FIG. 33 ; 
         FIG. 36  is a cross-sectional view of a distal end section of another inner needle according to the second modification of the third embodiment, taken along a plane passing through the center axis of the inner needle in the longitudinal direction; 
         FIG. 37  is a perspective view of the distal end section of the inner needle illustrated in  FIG. 36 ; 
         FIG. 38  is a cross-sectional view taken along line J-J in  FIG. 36 ; 
         FIG. 39  is a diagram for illustrating a distal end section of a biopsy needle according to a fourth embodiment; 
         FIG. 40  is a schematic view in the direction of arrow L in  FIG. 39 ; 
         FIG. 41  is a cross-sectional view taken along line K-K in  FIG. 39 ; 
         FIG. 42  is a diagram for illustrating a distal end section of another biopsy needle according to the fourth embodiment; 
         FIG. 43  is a schematic view in the direction of arrow N in  FIG. 42 ; 
         FIG. 44  is a cross-sectional view taken along line M-M in  FIG. 42 ; 
         FIG. 45  is a diagram for illustrating a distal end section of another biopsy needle according to the fourth embodiment; 
         FIG. 46  is a schematic view in the direction of arrow P in  FIG. 45 ; and 
         FIG. 47  is a cross-sectional view taken along line O-O in  FIG. 45 . 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following embodiments. The drawings referred to in the following description merely schematically illustrate the shapes, sizes, and positional relations to such degrees that the contents of the present invention are understandable. Accordingly, the present invention is not limited only to the shapes, sizes, and positional relations exemplified in the individual drawings. While the following description exemplifies a biopsy needle configured to puncture the interior of body tissue of an animal including a human and to collect the body tissue, the present invention is not limited by the embodiments. The same reference signs are used to designate the same elements throughout the drawings. 
     First Embodiment 
       FIG. 1  is a diagram for illustrating a distal end section of a biopsy needle according to a first embodiment. (1) of  FIG. 1  is a plan view of the distal end section of the biopsy needle according to the first embodiment, and (2) of  FIG. 1  is a side view of the distal end section of the biopsy needle according to the first embodiment.  FIG. 2  is a cross-sectional view taken along line A-A in  FIG. 1 .  FIG. 3  is a cross-sectional view taken along line B-B in  FIG. 1 . 
     As illustrated in  FIGS. 1 to 3 , a biopsy needle  100  according to the first embodiment includes a tubular outer needle  110  and an inner needle  120  that is solid and columnar. The outer needle  110  extends in a longitudinal direction. The inner needle  120  is configured to be inserted into and movable in the outer needle  110  in the longitudinal direction of the outer needle. As described below, the biopsy needle  100  further includes an operating unit (not illustrated) internally housing a proximal end of the outer needle  110  and the inner needle  120  and having a moving mechanism for sliding the outer needle  110  and the inner needle  120  independently in the longitudinal direction. 
     The outer needle  110  has a tubular shape with a pointed distal end, and includes a needle tip  111  (first needle tip) at the distal end in the longitudinal direction. The outer needle  110  is formed of a biocompatible material, for example, metal such as stainless steel, titanium, aluminum, or a resin such as a fluororesin. 
     Similarly to the outer needle  110 , the inner needle  120  is formed of a biocompatible material and includes a distal end portion and a notch portion  123 . The distal end portion includes a needle tip  121  (second needle tip) and an inclined surface  122 . The needle tip  121  is formed at the distal end of the inner needle. The inclined surface  122  is inclined toward the needle tip  121  at the distal end. The notch portion  123  includes a notch for collecting body tissue formed on the side surface on more proximal end side compared with the inclined surface  122 . The needle tip  121  is located on a plane passing through the center axis of the inner needle  120  in the longitudinal direction. When viewing in the transverse direction, the distal end of the inner needle  120  is cut so as to form a top portion on an opposite side of the inclined surface  122 , whereby the needle tip  121  is tapered. The inclined surface  122  is formed by a processing method such as a lancet, a back cut, a ceramic set, or flat grinding. In the notch portion  123 , a notch is formed by cutting out the columnar portion along the longitudinal direction so as to form a cutout surface into a flat surface at a section on more proximal end side compared with the inclined surface  122  (refer to  FIG. 3 ). In the notch portion  123 , the distal end surface and the proximal end surface are inclined from the bottom surface toward the upper portion of the notch portion  123  in side view. The inner needle  120  may have a prismatic shape in addition to a columnar shape. 
     Furthermore, the inner needle  120  includes a groove  124  (guide portion) communicating from the distal end portion to the notch portion  123 . As illustrated in  FIGS. 1 and 2 , the groove  124  is formed by cutting on the inner needle  120  in a V shape beginning from the proximal end of the inclined surface  122  to the distal end surface of the notch portion  123 . In the examples of  FIGS. 1 to 3 , the depth of the groove  124  is set to be shallower than the depth of the notch portion  123 . The notch portion  123  and the groove  124  are located on the side opposite to the formation portion (top portion) of the needle tip  121  in the transverse direction. 
       FIG. 4  is a cross-sectional view of the distal end section of the biopsy needle  100  after the body tissue collection, taken along a plane passing through the center axis of the biopsy needle  100  in the longitudinal direction and the center of the needle tip  121  of the inner needle  120 . When body tissue is punctured, the body tissue naturally enters the groove  124  on the distal end side by energy at the time of ejection of the inner needle  120 , and by further ejecting the inner needle  120 , the body tissue is introduced to the notch portion  123  on more proximal end side compared with the groove  124 , via the groove  124 . Moreover, even in a case where the notch portion  123  has not reached a body tissue collection target region, the collection target body tissue can be accommodated in the groove  124  as long as the groove  124  has reached the body tissue collection target region. As illustrated in  FIG. 4 , the biopsy needle  100  can accommodate body tissue  2   b  in both the distal end-side groove  124  and the proximal end-side notch portion  123 . Accordingly, it is possible to collect a large amount of body tissue compared with the configuration without the groove  124 . 
       FIG. 5  is a diagram for illustrating a biopsy method implemented by the biopsy needle  100  illustrated in  FIG. 1 . As illustrated in  FIG. 5 , using the ultrasonic tomogram by an ultrasound endoscope as a guide, an insertion unit  10  of the ultrasound endoscope is allowed to reach a prostate  2  as a biopsy target via a urethra  3  of the patient. The distal end of the biopsy needle inserted into the treatment tool channel of the insertion unit  10  is caused to protrude from an opening  11  at the distal end of the insertion unit  10 , and the prostate  2  is punctured by the outer needle  110  and the inner needle  120 . In this case, the distal end of the inner needle  120  is caused to protrude from the outer needle  110  until at least the groove  124  is exposed. With protrusion of the inner needle  120 , body tissue is sequentially introduced via the groove  124  to the notch portion  123  on more proximal end side compared with the groove  124 . Thereafter, the outer needle  110  is caused to advance in the distal end direction, and while the body tissue that has entered the groove  124  and the notch portion  123  is cut by the distal end of the outer needle  110 , the groove  124  and the notch portion  123  are covered with the outer needle  110  in a state where the body tissue is caught inside the groove  124  and the notch portion  123 . In this state, the biopsy needle is pulled out of the body via the treatment tool channel, and thereafter, the body tissue caught in the groove  124  and the notch portion  123  is collected. A bladder  4  is located behind the prostate  2 . 
     A conventional biopsy needle will now be described.  FIG. 6  is a diagram for illustrating a distal end section of a biopsy needle according to a conventional technique. (1) of  FIG. 6  is a plan view of the distal end section of the biopsy needle according to the conventional technique, and (2) of  FIG. 6  is a side view of the distal end section of the biopsy needle according to the conventional technique.  FIG. 7  is a cross-sectional view taken along line C-C in  FIG. 6 .  FIGS. 8 to 10  are cross-sectional views of the distal end section of the biopsy needle according to the conventional technique after the body tissue collection, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction and the center of the needle tip of the inner needle. 
     As illustrated in  FIGS. 6 and 7 , a conventional biopsy needle  100 P is configured, in order to collect body tissue, to include solely a notch portion  123 P obtained by cutting out the side surface on the distal end side of an inner needle  120 P so as to obtain a semicircular cross-section. Accordingly, the region between the proximal end of an inclined surface  122 P and the notch portion  123 P has a solid cylindrical shape (refer to  FIG. 7 ). Therefore, in a case where the biopsy needle  100 P is used, there is a need to cause the inner needle  120 P to protrude from an outer needle  110 P until the notch portion  123 P is exposed, in order to collect body tissue  2   b  into the notch portion  123 P as illustrated in  FIG. 8 . In addition, in the conventional biopsy needle  100 P, in order to reliably cover a portion up to the distal end of the notch portion  123 P with the outer needle  110 P so as not to allow the body tissue to be released from the notch portion  123 P after the body tissue collection, there is a need, as illustrated in  FIG. 9 , to allow a certain margin by increasing a length P 1  from a needle tip  121 P of the inner needle  120 P to the notch portion  123 P to a length of about 5 to 6 mm. For this reason, with the conventional biopsy needle  100 P, there is a need to puncture to reach a depth 5 to 6 mm deeper than the depth of the site including the tissue to be collected with the needle tip  121 P of the inner needle  120 P. Moreover, as an attempt to perform tissue collection without inserting the needle deeply into the tissue, as in a biopsy needle  100 P′ illustrated in  FIG. 10 , there is an examined configuration in which a notch portion  123 P′ is extended in the distal end direction to the vicinity of the proximal end of an inclined surface  122 P′, having a length P 2  of an inner needle  120 P′ protruding from the tissue collection target site being reduced to about 2 to 3 mm. In the configuration illustrated in  FIG. 10 , however, the notch portion  123 P′ extends to the vicinity of the proximal end of the inclined surface  122 P′, and this might reduce the strength of the distal end portion of the inner needle  120 P′, leading to bending of the inner needle  120 P′ in a case where the inner needle  120 P′ punctures hard tissue. 
     In contrast, the inner needle  120  according to the first embodiment merely includes the groove  124  communicating from the distal end portion to the notch portion  123 , with the notch portion  123  being arranged at a same position. This configuration makes it possible to maintain the strength of the portion from the distal end portion to the notch portion  123  and to easily transmit puncture force to the needle tip  121 , and thus, can avoid bending of the inner needle  120  even when the inner needle  120  punctures the hard tissue. 
     Moreover, in the first embodiment, the groove  124  leading from the distal end portion to the notch portion  123  is formed, and the body tissue can be collected when at least the groove  124  reaches the body tissue collection target region. Therefore, according to the first embodiment, it is sufficient, at the time of biopsy, that the groove  124  on more distal end side compared with the notch portion  123  reaches the body tissue collection target region, and there is no need to cause the inner needle  120  to protrude to a degree to allow the notch portion  123  on the proximal end side to reach the inner needle  120 . Accordingly, it is possible to collect the body tissue in the vicinity of the needle tip  121  into the groove  124  and the notch portion  123  while reducing the protruding length of the inner needle  120 . Moreover, according to the first embodiment, the body tissue  2   b  can be accommodated in both the distal end-side groove  124  and the proximal end-side notch portion  123 , and thus, a large amount of body tissue can be collected. 
     Next, an overall configuration of the biopsy needle  100  will be described.  FIG. 11  is a cross-sectional view of the biopsy needle  100 , taken along a plane passing through the center axis of the biopsy needle  100  in the longitudinal direction and the center of the needle tip of the inner needle  120 . As illustrated in  FIG. 11 , in addition to the outer needle  110  and the inner needle  120 , the biopsy needle  100  further includes an operating unit  130  internally housing proximal ends of the outer needle  110  and the inner needle  120  and having a moving mechanism for sliding the outer needle  110  and the inner needle  120  independently in the longitudinal direction. 
     The operating unit  130  has a configuration with portions to achieve a function as a moving mechanism, including a trigger button  132 , an inner needle charging coil spring  133 , an inner needle slider  134 , an inner needle knob  135 , an inner needle stopper  136 , an outer needle fixing hook release lever  137 , an outer needle charging coil spring  138 , an outer needle slider  139 , an outer needle knob  140 , and an outer needle stopper  141 , being assembled onto a hollow and pillar-shaped operating unit main body  131 . 
     The operating unit main body  131  includes: a Luer fitting portion  131   a  provided at the distal end; a spring assembly protrusion  131   b  provided at the inner proximal end; a trigger button hole  131   c  provided at the upper portion of the spring assembly protrusion  131   b ; an inner needle knob groove  131   d  dug in the longitudinal direction provided at the proximal end-side bottom; and an outer needle knob groove  131   e  dug in the longitudinal direction provided at the distal end-side bottom. The distal ends of the outer needle  110  and the inner needle  120  protrude from the Luer fitting portion  131   a  in the distal end direction. A proximal end of an inner needle charging coil spring  133  described below is assembled to the spring assembly protrusion  131   b . A proximal end of a trigger button  132  described below protrudes from the trigger button hole  131   c . An inner needle knob  135  described below is slidable in the longitudinal direction in the inner needle knob groove  131   d . An outer needle knob  140  described below is slidable in the longitudinal direction in the outer needle knob groove  131   e . 
     The trigger button  132  serves as a trigger for advancing operation of the inner needle  120 , and both ends alternately rise and fall about a fulcrum  132   a  connected to the inside of the operating unit main body  131 . An inner needle fixing hook  132   b  to be caught in a recess of the inner needle slider  134  described below is provided at the distal end of the trigger button  132 . 
     The inner needle charging coil spring  133  has its proximal end being assembled to a proximal end portion of the spring assembly protrusion  131   b  and has its distal end being assembled to a proximal end-side surface of the inner needle slider  134  described below. The inner needle charging coil spring  133  is extended after compression (charging), thereby biasing the inner needle slider  134  toward the distal end direction. 
     The inner needle slider  134  is connected to the proximal end of the inner needle  120  and advances in the distal end direction by the biasing in the distal end direction by the inner needle charging coil spring  133 , and together with this, causes the inner needle  120  to advance in the distal end direction. A recess into which the inner needle fixing hook  132   b  fits is formed on the upper surface of the inner needle slider  134 . 
     The inner needle knob  135  is slidable along the inner needle knob groove  131   d  in the longitudinal direction. The upper surface of the inner needle knob  135  is connected to the bottom surface of the inner needle slider  134 . The lower portion of the inner needle knob  135  protrudes from the inner needle knob groove  131   d . The inner needle knob  135  advances in the inner needle knob groove  131   d  together with the advance of the inner needle slider  134 . Moreover, an operator of the biopsy needle  100  can retreat the inner needle slider  134  and the inner needle  120  toward the proximal end side by retreating the inner needle knob  135  toward the proximal end side along the inner needle knob groove  131   d . In a case where the inner needle knob  135  is retreated to the proximal end of the inner needle knob groove  131   d , the inner needle fixing hook  132   b  fits into the recess of the inner needle slider  134 , and the inner needle  120  is fixed at a position to be arranged at the most proximal end side. 
     The inner needle stopper  136  stops the advance operation of the inner needle slider  134 , and together with this stops the advance operation of the inner needle  120 . 
     Both ends of the outer needle fixing hook release lever  137  rise and fall about a fulcrum  137   a  connected to the inner needle stopper  136 . An outer needle fixing hook  137   b  to be caught in a recess of the outer needle slider  139  described below is provided at the distal end of the outer needle fixing hook release lever  137 . 
     The outer needle charging coil spring  138  has its proximal end being assembled to a distal end-side side surface of the inner needle stopper  136  and has its distal end being assembled to a proximal end-side side surface of the outer needle slider  139  described below, and extended after compression (charging), thereby biasing the outer needle slider  139  toward the distal end direction. 
     The outer needle slider  139  is connected to the proximal end of the outer needle  110  and advances in the distal end direction by the biasing in the distal end direction by the outer needle charging coil spring  138 . Together with this, the outer needle slider  139  causes the outer needle  110  to advance in the distal end direction. A recess into which the outer needle fixing hook  137   b  fits is formed on the upper surface of the outer needle slider  139 . 
     The outer needle knob  140  is slidable along the outer needle knob groove  131   e  in the longitudinal direction. The upper surface of the outer needle knob  140  is connected to the bottom surface of the outer needle slider  139 . The lower portion of the outer needle knob  140  protrudes from the outer needle knob groove  131   e . The outer needle knob  140  advances in the outer needle knob groove  131   e  together with the advance of the outer needle slider  139 . Moreover, the operator of the biopsy needle  100  retreats the outer needle slider  139  and the outer needle  110  toward the proximal end side by retreating the outer needle knob  140  toward the proximal end side along the outer needle knob groove  131   e  In a case where the outer needle knob  140  is retreated to the proximal end of the outer needle knob groove  131   e , the outer needle fixing hook  137   b  fits into the recess of the outer needle slider  139 , and the outer needle  110  is fixed at a position where it is arranged at the most proximal end side. 
     The outer needle stopper  141  is provided at the distal end portion of the operating unit main body  131 , stops the advance operation of the outer needle slider  139 , and together with this stops the advance operation of the outer needle  110 . 
     A length L 1  of the outer needle knob groove  131   e  in the longitudinal direction that is, the stroke (maximum slidable distance) L 1  of the outer needle  110  toward the distal end direction is set to be greater than a length L 2  of the inner needle knob groove  131   d  in the longitudinal direction, that is, a stroke L 2  of the inner needle  120  toward the distal end direction. The stroke L 2  is set so as to allow at least the groove  124  to be exposed from the needle tip  111  of the outer needle  110  to such a degree to enable tissue collection. 
     The biopsy needle  100  according to the present embodiment is configured to form the groove  124  leading from the distal end portion to the notch portion  123 , to define a first state and a second state and allow switching between the first state and the second state, thereby reliably reducing the protruding length of the inner needle  120  from the collection target at the time of biopsy to avoid penetration of the capsule  2   a  of the prostate  2  from the inside to the outside by the needle tip of the inner needle  120 , and enabling collection of the body tissue into the groove  124  and the notch portion  123 . The biopsy needle  100  defines the first state and the second state by setting the longitudinal stroke L 1  of the outer needle  110  greater than the longitudinal stroke L 2  of the inner needle  120 . Next, the first state and the second state of the biopsy needle  100  will be described. 
       FIG. 12  is a diagram illustrating the first state and the second state of the biopsy needle  100  illustrated in  FIG. 1 , being a cross-sectional view of the distal end section of the biopsy needle  100  taken along a plane passing through the center axis of the biopsy needle  100  in the longitudinal direction and passing through the needle tip  121  of the inner needle  120 .  FIG. 12  (a) is a diagram illustrating the first state. The first state is a charging state in which both the inner needle charging coil spring  133  and the outer needle charging coil spring  138  are compressed and charging energy for extension. In other words, the first state is a state of charging the energy for causing the outer needle  110  and the inner needle  120  to protrude, and the state in which the outer needle  110  and the inner needle  120  puncture the biopsy site. As illustrated in (a) of  FIG. 12 , the needle tip  121  of the inner needle  120  is located on more distal end side of the needle tip  111  compared with the outer needle  110  in the first state. Moreover, the needle tip  111  of the outer needle  110  is ideally located, in the first state, at more distal end side compared with the distal end of the groove  124  so as to prevent the body tissue other than the collection target from entering the groove  124  before reaching the collection target body tissue. 
     In  FIG. 12 , (b) is a diagram illustrating the second state of the biopsy needle  100 , being a cross-sectional view of the distal end section of the biopsy needle  100  taken along a plane passing through the center axis in the longitudinal direction and passing through the needle tip  121  of the inner needle  120 . The second state is a state in which the inner needle  120  and the outer needle  110  have slid to the biopsy site in the distal end direction and the biopsy collection is completed. In the second state, the needle tip  111  of the outer needle  110  is located on more distal end side compared with the needle tip  121  of the inner needle  120 . That is, the outer needle  110  covers the entire groove  124  of the inner needle  120 . 
     Next,  FIG. 13  is a diagram illustrating the protruding operation of the outer needle  110  and the inner needle  120  in the biopsy needle  100  illustrated in  FIG. 1 .  FIG. 13  illustrates a case where the inner needle  120  and the outer needle  110  protrude in the x-axis direction. Moreover,  FIG. 13  is a cross-sectional view of the distal end section of the biopsy needle  100  taken along a plane passing through the center axis of the biopsy needle  100  in the longitudinal direction and passing through the needle tip  121  of the inner needle  120 . 
     In  FIG. 13 , (a) illustrates the first state (charging state) in which the needle tip  121  of the inner needle  120  is located on more distal end side compared with the needle tip  111  of the outer needle  110 , being the state before puncturing a site in the vicinity of the capsule  2   a  of the prostate  2  as a biopsy site. 
     In  FIG. 13 , (b) illustrates a state in which the inner needle  120  alone protrudes in the x-axis direction on the distal end side with the movement of the inner needle  120  by the moving mechanism to collect the tissue in the vicinity of the capsule  2   a  of the prostate  2 . In this case, the inner needle  120  protrudes in the x-axis direction by the stroke L 2  as compared with the first state. Accordingly, the needle tip  121  of the inner needle  120  reaches a position B 2  in the close proximity of the capsule  2   a , the position moved in the x-axis direction by the stroke L 2  from a position B 1  in the first state. With this configuration, the groove  124  is sufficiently exposed, and the tissue of the prostate  2  enters the groove  124 . Furthermore, the tissue of the prostate  2  enters the notch portion  123  via the groove  124 . 
     In  FIG. 13 , (c) illustrates a state in which the outer needle  110  has also protruded and the biopsy operation has been finished, that is, in the second state. The outer needle  110  protrudes more in the x-axis direction by the stroke L 1  compared with the first state. This stroke L 1  is greater than the stroke L 2 . Accordingly, the needle tip  111  of the outer needle  110  located at a position B 3  on more proximal end side compared with the needle tip  121  of the inner needle  120  in the first state exceeds the notch portion  123  and the groove  124  of the inner needle  120 , and then, reaches a position B 4  beyond the needle tip  121  of the inner needle  120 . By the protrusion of the outer needle  110 , while the tissue of the prostate  2  that has entered the notch portion  123  and the groove  124  is cut by the needle tip  111  of the outer needle  110 , the notch portion  123  and the groove  124  can be completely covered with the outer needle  110  in a state where the body tissue  2   b  is caught inside the notch portion  123  and the groove  124 . 
     In this manner, in the biopsy needle  100  according to the present embodiment, by setting the longitudinal stroke L 1  of the outer needle  110  greater than the longitudinal stroke L 2  of the inner needle  120 , it is possible to switch between the first state as a charging state in which the needle tip  121  of the inner needle  120  is located on more distal end side than the needle tip  111  of the outer needle  110  and a second state in which the needle tip  111  of the outer needle  110  is located on more distal end side than the needle tip  121  of the inner needle  120  as a result of sliding of the inner needle  120  and the outer needle  110  in the distal end direction. This configuration makes it possible to reliably collect the body tissue  2   b  into the notch portion  123  and the groove  124 . Moreover, as described above, the biopsy needle  100  has the protruding length of the inner needle  120  at the time of biopsy formed to be shorter than the length in the conventional case. Accordingly, penetration of the capsule  2   a  of the prostate  2  from the inside to the outside with the needle tip  121  of the inner needle  120  is significantly less likely to occur. 
     The biopsy operation of the biopsy needle  100  will be described in more detail.  FIGS. 14A to 14F  are diagrams for illustrating the biopsy operation of the biopsy needle  100  illustrated in  FIG. 11 , being a cross-sectional view of the biopsy needle  100  taken along a plane passing through the center axis of the biopsy needle  100  in the longitudinal direction and passing through the center of the needle tip of the inner needle  120 . 
       FIG. 14A  is a diagram illustrating the first state of the biopsy needle  100  described above. As illustrated in  FIG. 14A , in the first state, the inner needle fixing hook  132   b  is caught in the recess of the inner needle slider  134 , and the outer needle fixing hook  137   b  is caught in the recess of the outer needle slider  139 , and the inner needle charging coil spring  133  and the outer needle charging coil spring  138  are compressed and charging energy for extension. 
     As illustrated by arrow Ya in  FIG. 14B , when the trigger button  132  is pressed, the inner needle fixing hook  132   b  at the distal end portion is raised about the fulcrum  132   a  and disengaged from the recess of the inner needle slider  134 . As illustrated in  FIG. 14C , the compressed inner needle charging coil spring  133  extends in the distal end direction, and the inner needle slider  134  is biased by the extension of the inner needle charging coil spring  133  and slides in the distal end direction as indicated by arrow Yb. Together with this, the inner needle  120  also slides in the distal end direction as indicated by arrow Yc. 
     Then, as illustrated in  FIG. 14D , the inner needle slider  134  and the inner needle knob  135  slide in the distal end direction by the biasing of the inner needle charging coil spring  133  until the inner needle slider  134  and the inner needle knob  135  abut the inner needle stopper  136 . With this operation, the inner needle  120  protrudes in the x-axis direction by the stroke L 2 . Furthermore, when the inner needle slider  134  presses the outer needle fixing hook release lever  137  from the proximal end as indicated by arrow Yd by the biasing of the inner needle charging coil spring  133 , the outer needle fixing hook  137   b  at the distal end portion is raised about the fulcrum  137   a  as indicated by arrow Ye and disengaged from the recess of the outer needle slider  139 . With this operation, as illustrated in  FIG. 14E , the compressed outer needle charging coil spring  138  extends in the distal end direction. Biased by the extension of the outer needle charging coil spring  138 , the outer needle slider  139  and the outer needle knob  140  move in the distal end direction until they abut the outer needle stopper  141  as illustrated by arrow Yf. With this configuration, as illustrated by arrow Yg, the outer needle  110  protrudes in the x-axis direction by the stroke L 1  while cutting the tissue that has entered the notch portion  123  by the needle tip  111 , and then, the biopsy needle  100  is switched to the second state illustrated in  FIG. 14F . 
     The operator of the biopsy needle  100  extracts the biopsy needle  100  from the biopsy site in this state. Subsequently, by moving the outer needle knob  140  to the proximal end of the outer needle knob groove  131   e , the outer needle  110  is retreated ( FIG. 14D ), the body tissue inside the notch portion  123  is collected after the notch portion  123  is exposed. Thereafter, the inner needle knob  135  is moved to the proximal end of the inner needle knob groove  131   d  ( FIG. 14A ), thereby switching the biopsy needle  100  to the first state. 
     As described above, the biopsy needle  100  includes the moving mechanism in which the longitudinal stroke L 1  of the outer needle  110  is set to be longer than the longitudinal stroke L 2  of the inner needle  120  and configured to slidably move the outer needle  110  and the inner needle  120  independently in the longitudinal direction. With this configuration, it is possible to switch between the first state and the second state. 
     First Modification of First Embodiment 
       FIG. 15  is a cross-sectional view of a distal end section of a biopsy needle according to a first modification of the first embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction.  FIG. 16  is a cross-sectional view taken along line D-D in  FIG. 15 . As illustrated by an inner needle  120 A in  FIGS. 15 and 16 , a groove  124 A that allows communication between the distal end portion and the notch portion  123  may have a semicircular cutout shape. 
     Second Modification of First Embodiment 
       FIG. 17  is a plan view of the distal end section of the biopsy needle according to a second modification of the first embodiment.  FIG. 18  is a cross-sectional view of the distal end section of the biopsy needle according to the second modification of the first embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction. ( 1 ) of  FIG. 18  is a diagram illustrating the first state of the biopsy needle according to the second modification of the first embodiment, and ( 2 ) of  FIG. 18  illustrates the second state of the biopsy needle according to the second modification of the first embodiment. 
     As illustrated in  FIG. 17 , an outer needle  110 B may be turned upside down in the radial direction with respect to the inner needle  120 . That is, the cutout at the distal end of the outer needle  110 B and the inclined surface  122  may be parallel to each other. In this case, as illustrated in ( 1 ) of  FIG. 18 , the outer needle  110 B does not need to cover the entire groove  124  in the first state as long as a needle tip  111 B of the outer needle  110 B reaches part of the inclined surface  122 . That is, there is no problem with puncture of the biopsy needle into the body tissues as long as a region obtained by projecting the needle tip  111 B of the outer needle  110 B onto the transverse direction of the outer needle  110 B and the inner needle  120  overlaps with the inclined surface  122  of the inner needle  120 . Also in the second modification of the first embodiment, in the second state as illustrated in ( 2 ) of  FIG. 18 , there is a need to locate the needle tip  111 B of the outer needle  110 B on more distal end side than the needle tip  121  of the inner needle  120  to cover, with the outer needle  110 B, the distal end of the groove  124  of the inner needle  120  and to reliably catch the body tissues into the notch portion  123  and the groove  124 . 
     Second Embodiment 
     Next, a second embodiment will be described.  FIG. 19  is a diagram for illustrating a distal end section of a biopsy needle according to the second embodiment. ( 1 ) of  FIG. 19  is a plan view of the distal end section of the biopsy needle according to the second embodiment, and ( 2 ) of  FIG. 19  is a side view of the distal end section of the biopsy needle according to the second embodiment.  FIG. 20  is a cross-sectional view of the distal end section of biopsy needle according to the second embodiment after the body tissue collection, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction. 
     As illustrated in ( 1 ) of  FIG. 19  and ( 2 ) of  FIG. 19 , the biopsy needle according to the second embodiment includes an inner needle  220  from which a distal end section D 1  of the inner needle  120 A illustrated in  FIG. 15  has been cut out. The inner needle  220  has a shape in which the distal end section D 1  of the inner needle  120 A is cut out so that an inclined surface  222  is formed on a side opposite to the inclined surface  122  of the inner needle  120 A. The inclined surface  222  is set such that the inclined surface  222  of the inner needle  220  and an inclined surface  112  of the outer needle  110  are substantially parallel to each other. Therefore, the needle tip of the inner needle  220  is divided into two needle tips  221   a  and  221   b  from a position C 1 . 
     Since the inclined surface  222  of the inner needle  220  and the inclined surface  112  of the outer needle  110  are substantially parallel to each other, as illustrated in  FIG. 20 , it is possible to store the needle tips  221   a  and  221   b  of the inner needle  220  in the outer needle  110  merely by causing the needle tip  111  of the outer needle  110  to slightly protrude to the distal end side of the needle tip  221   a  of the inner needle  220 . Moreover, the groove  124  is formed in the inner needle  220  so as to communicate with the notch portion  123  from the position C 1  between the needle tips  221   a  and  221   b . Therefore, the body tissue  2   b  can be collected by substantially the distal end of the inner needle  220 , and it is also possible to collect the body tissue in a state where the needle tips  221   a  and  221   b  of the inner needle  220  do not protrude from the body tissue collection target region. Since the needle tips  221   a  and  221   b  of the inner needle  220  can also be stored inside the outer needle  110  merely by causing the needle tip  111  to slightly protrude to the distal end side of the needle tip  221   a  of the inner needle  220 . Accordingly, the needle tip  111  of the outer needle  110  has substantially no protrusion from the body tissue collection target region, and thus, there is no possibility of damaging a section outside the collection target region. 
     In the second embodiment, the groove formed in the inner needle is not limited to the V-shaped groove  124 , but may be a groove  124 A (refer to  FIG. 16 ) in a semicircular cutout shape. 
     First Modification of Second Embodiment 
       FIG. 21  is a diagram for illustrating the distal end section of the biopsy needle according to a first modification of the second embodiment.  FIG. 21  illustrates, for the purpose of explanation, the outer needle in a cross-section taken along a plane passing through the center axis of the outer needle in the longitudinal direction.  FIG. 22  is a perspective view of the distal end portion of the inner needle illustrated in  FIG. 21 .  FIG. 23  is a cross-sectional view taken along line E-E in  FIG. 21 . 
     As illustrated by an inner needle  220 A in  FIGS. 21 to 23 , D cutting is performed on two surfaces  225 A such that a needle tip  221 A is formed at the position C 1 , and then, a section including the needle tips  221   a  and  221   b  of the inner needle  220  illustrated in  FIG. 19  are cut off. With this shape, the groove  124  directly leads to the notch portion  123  from the needle tip  221 A (position C 1 ), and thus, the body tissue  2   b  can be collected by the most distal end of the inner needle  220 A. Accordingly, it would be sufficient with substantially no protrusion of the inner needle  220 A and the outer needle  110  from the body tissue collection target region. Moreover, the configuration of the inner needle  220 A with the needle tip that is not divided into two reduces the resistance at the time of puncture, and achieves easy transmission of the force of puncture to the needle tip  221 A, making it possible to perform puncture with less force. 
       FIG. 24  is a plan view of the distal end section of another biopsy needle according to the first modification of the second embodiment. As an inner needle  220 B illustrated in  FIG. 24 , it is also possible to adopt a shape obtained by cutting off a needle tip  221   b  section of the inner needle  220  illustrated in  FIG. 19  by D cutting performed on a surface  225 B Since this shape of the inner needle  220 B with the needle tip is not divided into two, the resistance at the time of puncture is reduced, and easy transmission of the force of puncture to the needle tip  221   a  is achieved, making it possible to perform puncture with less force. 
     Second Modification of Second Embodiment 
     Next, second modification the second embodiment will be described.  FIG. 25  is a diagram for illustrating a distal end section of a biopsy needle according to a second modification of the second embodiment. ( 1 ) of  FIG. 25  is a plan view of the distal end section of the biopsy needle according to the second modification of the second embodiment, and ( 2 ) of  FIG. 25  is a side view of the distal end section of the biopsy needle according to the second modification of the second embodiment. For the purpose of explanation, the outer needle is illustrated in a cross-sectional state taken along a plane passing through the center axis of the outer needle in the longitudinal direction. A groove  224 C of an inner needle  220 C in  FIG. 25  is formed such that the bottom of the groove  224 C is inclined from the position C 1  of the distal end portion toward a center C 2  of a connecting portion with the notch portion  123 , as compared with the groove  124  of the inner needle  220  illustrated in  FIG. 19 . In other words, the groove  224 C is formed so that its depth becomes shallower toward the distal end portion. In this case, the protrusion of the inner needle  220 C allows the body tissue to enter the groove  224 C in a state where the needle tip side is thinner than the notch portion  123  side. This configuration makes it is easier to perform cutting by the distal end of the outer needle  110  and makes it possible to reliably gather the body tissue into the grooves  224 C and the notch portion  123 . Of course, similarly to the second embodiment, the body tissue can be collected by the substantially distal end of the inner needle  220 C. 
       FIG. 26  is a diagram illustrating another example of the distal end section of the biopsy needle according to the second modification of the second embodiment.  FIG. 26  illustrates, for the purpose of explanation, the outer needle in a cross-section taken along a plane passing through the center axis of the outer needle in the longitudinal direction.  FIG. 27  is a sectional view taken along line F-F in  FIG. 26 . 
     As illustrated by an inner needle  220 D in  FIGS. 26 and 27 , it is allowable to provide a step on the bottom of the groove such that a groove  224 D- 1  on the distal end portion side is shallower than a groove  224 D- 2  on the connecting portion side with the notch portion  123 . Also in this case, the body tissue enters the grooves  224 D- 1 , and  224 D- 2  in a state where the needle tip side is thinner than the notch portion  123  side, making it easier to perform cutting by the distal end of the outer needle  110 . 
       FIG. 28  is a diagram illustrating another example of the distal end section of the biopsy needle according to the second modification of the second embodiment. Similarly,  FIG. 28  illustrates, for the purpose of explanation, the outer needle in a cross-section taken along a plane passing through the center axis of the outer needle in the longitudinal direction. As in the inner needle  220 E illustrated in  FIG. 28 , a protrusion  224 E may be provided in the middle of the groove  124 . With this protrusion  224 E, the body tissue that has entered the groove  124  becomes thinner in the middle, achieving smooth cutting by the distal end of the outer needle  110 . Since the body tissue is likely to be cut at the position of the protrusion  224 E, it is preferable to arrange the protrusion  224 E on more distal end side rather than the proximal end side of the groove  124  in order to increase the amount of body tissue to be collected in the groove  124 . 
     Third Embodiment 
     Next, a third embodiment will be described.  FIG. 29  is a cross-sectional view of a distal end section of the biopsy needle according to the third embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction. In  FIG. 29 , the distal end shape of the inner needle before formation of the cutout portion is indicated by broken line La.  FIG. 30  is a cross-sectional view taken along line G-G in  FIG. 29 . 
     As illustrated in  FIGS. 29 and 30 , in the third embodiment, the inner needle  320  includes a cutout portion  324  (guide portion) formed instead of the groove  124  illustrated in  FIG. 1 . The cutout portion  324  is formed by cutting out a section from the proximal end of the inclined surface  122  of the distal end portion to the notch portion  123  in the longitudinal direction. Even in a case where the cutout portion  324  is formed, body tissue naturally enters the cutout portion  324  by energy at the time of ejection of the inner needle  320  when the body tissue is punctured. Subsequently, by allowing the inner needle  320  to further eject, the body tissue is introduced to the notch portion  123  via the cutout portion  324 . Therefore, even in the case where the cutout portion  324  is formed, as long as cutout portion  324  reaches the body tissue collection target region, the cutout portion  324  guides entry of body tissue into the notch portion  123 , making it possible to accommodate the collection target body tissue in the notch portion  123 . 
     First Modification of Third Embodiment 
     Next, a first modification the third embodiment will be described.  FIG. 31  is a cross-sectional view of the distal end section of the biopsy needle according to the first modification of the third embodiment, taken along a plane passing through the center axis of the biopsy needle in the longitudinal direction. In  FIG. 31 , the distal end shape of the inner needle before forming the cutout portion is indicated by broken line Lb.  FIG. 32  is a cross-sectional view taken along line H-H in  FIG. 31 . As illustrated in an inner needle  320 A in  FIGS. 31 and 32 , a cutout surface of a cutout portion  324 A may be inclined from a proximal end  326  of the inclined surface  122  as the distal end portion toward a connecting portion  327  with the notch portion  123 . Even in this case, similarly to the groove  224 C of the inner needle  220 C illustrated in  FIG. 25 , a gap between the inner needle  320 A and the outer needle  110  becomes narrower toward the distal end portion. This makes it easier to perform cutting by the distal end of the outer needle  110 , making it possible to reliably gather the body tissue into the cutout portion  324 A and the notch portion  123 . 
     Second Modification of Third Embodiment 
     Next, a second modification of the third embodiment will be described.  FIG. 33  is a side view of the distal end section of the inner needle according to the second modification of the third embodiment. In  FIG. 33 , the distal end shape of the inner needle before forming the cutout portion is indicated by broken line Lc.  FIG. 34  is a perspective view of the distal end section of the inner needle illustrated in  FIG. 33 .  FIG. 35  is a cross-sectional view taken along line I-I in  FIG. 33 . 
     While the inner needle  320  illustrated in  FIG. 29  has a configuration in which the notch portion  123  and the cutout portion  324  are located on the side different from the needle tip  121  at the distal end of the inclined surface  122  in the transverse direction, an inner needle  320 B according to the second modification of the third embodiment illustrated in  FIGS. 33 to 35  is configured to arrange the notch portion  123  and the cutout portion  324  on the same side as a needle tip  321 B at the distal end of an inclined surface  322 B in the transverse direction. With this shape, the cutout portion  324  starts directly from the needle tip  321 B, and thus, the body tissue can be collected by the distal end of the inner needle  320 B. Accordingly, it would be sufficient with substantially no protrusion of the inner needle  320 B and the outer needle  110  from the body tissue collection target region. Furthermore, the inner needle  320 B is formed such that the side of the needle tip  321 B undergoes D cutting from both sides on a surface  325 B to taper the needle tip  321 B, achieving easy transmission of the force of puncture to the needle tip  321 B. 
       FIG. 36  is a cross-sectional view of a distal end section of another inner needle according to the second modification of the third embodiment taken along a plane passing through the center axis of the inner needle in the longitudinal direction.  FIG. 37  is a perspective view of the distal end section of the inner needle illustrated in  FIG. 36 .  FIG. 38  is a sectional view taken along line J-J in  FIG. 36 . While the inner needle  320 A illustrated in  FIG. 31  has a configuration in which the notch portion  123  and the cutout portion  324 A are positioned on the side different from the needle tip  121  formation portion (top portion) at the distal end of the inclined surface  122  in the transverse direction, an inner needle  320 C illustrated in  FIGS. 36 to 38  is configured to arrange the notch portion  123  and the cutout portion  324 A on the same side as a formation portion of a needle tip  321 C at the distal end of an inclined surface  322 C in the transverse direction. Also in this case, the cutout portion  324 A leads directly from the needle tip  321 C to the notch portion  123 , and thus, the body tissue can be collected by the distal end of the inner needle  320 C. Accordingly, it would be sufficient with substantially no protrusion of the inner needle  320 C and the outer needle  110  from the body tissue collection target region. In the inner needle  320 C, since the cutout surface of the cutout portion  324 A has a shape that is inclined from the needle tip  321 C toward the proximal end, the distal end of the inner needle  320 C is not cut out. Accordingly, the needle tip  321 C can maintain the pointed shape and there is no need to perform D cutting on the side surface of the distal end portion. 
     Fourth Embodiment 
     Next, a fourth embodiment will be described.  FIG. 39  is a diagram for illustrating a distal end section of a biopsy needle according to the fourth embodiment.  FIG. 39  illustrates, for the purpose of explanation, the outer needle in a cross-section taken along a plane passing through the center axis of the outer needle in the longitudinal direction.  FIG. 40  is a schematic view in the direction of arrow L in  FIG. 39 .  FIG. 41  is a cross-sectional view taken along line K-K in  FIG. 39 . 
     In comparison with the inner needle  220 A in  FIGS. 21 to 23 , an inner needle  420  of the fourth embodiment illustrated in  FIGS. 39 to 41  is configured to include a rib  428  provided in a notch portion  423  to reinforce the inner needle strength. With this configuration, the inner needle  420  achieves easier transmission of the puncture force for the needle tip  221 A, making it possible to puncture harder tissue. In addition, it is also possible to extend the notch portion  423  further to the distal end, compared with the inner needle  220 A in  FIGS. 21 to 23 . 
       FIG. 42  is a diagram for illustrating a distal end section of another biopsy needle according to the fourth embodiment.  FIG. 42  illustrates, for the purpose of explanation, the outer needle in a cross-section taken along a plane passing through the center axis of the outer needle in the longitudinal direction.  FIG. 43  is a schematic view in the direction of arrow N in  FIG. 42 .  FIG. 44  is a cross-sectional view taken along line M-M in  FIG. 42 . For the inner needle  320 B illustrated in  FIGS. 33 to 35 , as the case of an inner needle  420 A illustrated in  FIGS. 42 to 44 , it is also allowable to provide the rib  428  in the notch portion  423  to reinforce the inner needle strength, thereby further extending the notch portion  423  to the distal end side. 
       FIG. 45  is a diagram for illustrating a distal end section of another biopsy needle according to the fourth embodiment.  FIG. 45  illustrates, for the purpose of explanation, the outer needle in a cross-section taken along a plane passing through the center axis of the outer needle in the longitudinal direction.  FIG. 46  is a schematic view in the direction of arrow P in  FIG. 45 .  FIG. 47  is a sectional view taken along line O-O in  FIG. 45 . As illustrated in an inner needle  420 C in  FIGS. 45 to 47 , it is allowable to extend the cutout portion  324  at the distal end of the inner needle  420 A illustrated in  FIGS. 42 to 44  and to form a cutout portion  424 C obtained by cutting out an upper portion of a rib  428 C from distal end to the proximal end of the rib  428 C. According to the inner needle  420 C with this configuration, it is possible to increase the amount of body tissue to be collected by the amount of formation of the cutout portion  424 C, enabling communication between the notch portions  423  partitioned by the rib  428 C with the cutout portion  424 C. Accordingly, it is possible to take out almost all of the collected body tissue from one of the notch portions  423 , leading to achieving an effect of reducing the number of times of operation of taking out the body tissue from the biopsy needle to once. 
     Although the tissue of the prostate  2  is collected using the biopsy needle  100  in the embodiments, the biopsy needle  100  may also be used to collect tissues of any other site. Moreover, although the distal end of the biopsy needle  100  is allowed to reach the biopsy site via the treatment tool channel of the insertion unit  10  of the ultrasound endoscope in the embodiments, it is possible to perform puncture by the biopsy needle  100  from outside of the body without going through the treatment tool channel of the ultrasonic endoscope, depending on the biopsy site. 
     A biopsy needle according to some embodiments includes an outer needle being tubular and having a first needle tip at one end of the outer needle in a longitudinal direction, and an inner needle having a pillar shape and configured to be inserted into and movable in the outer needle in the longitudinal direction of the outer needle. The inner needle includes a distal end portion having a second needle tip at a distal end of the inner needle and having an inclined surface inclined toward the second needle tip at the distal end, a notch portion having a notch on a side surface closer to a proximal end side of the inner needle than the inclined surface to collect body tissues, and a guide portion leading from the distal end portion to the notch portion. With this structure, it is possible to reliably collect the tissues via the guide portion. Since the guide portion leads to the distal end portion, it is possible to reduce a length of the biopsy needle protruding from a tissue collection target site at the time of collecting the tissues. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 
     REFERENCE SIGNS LIST 
     
         
           2  PROSTATE 
           2   a  CAPSULE 
           3  URETHRA 
           4  BLADDER 
           10  INSERTION UNIT 
           11  OPENING 
           100 ,  100 P,  100 P′ BIOPSY NEEDLE 
           110 ,  110 B,  110 P OUTER NEEDLE 
           111 ,  111 B,  111 P,  121 ,  121 P,  221   a ,  221   b ,  221 A,  321 B,  321 C NEEDLE TIP 
           112 ,  122 ,  122 P,  122 P′,  222 ,  322 B,  322 C INCLINED SURFACE 
           120 ,  120 A,  120 P,  120 P′,  220 ,  220 A,  220 B,  220 C,  220 D,  220 E,  320 ,  320 A,  320 B,  320 C,  420 ,  420 A,  420 C INNER NEEDLE 
           123 ,  123 P,  123 P′,  423  NOTCH PORTION 
           124 ,  124 A,  224 C,  224 D- 1 ,  224 D- 2  GROOVE 
           130  OPERATING UNIT 
           131  OPERATING UNIT MAIN UNIT 
           131   a  LUER FITTING PORTION 
           131   b  SPRING ASSEMBLY PROTRUSION 
           131   c  TRIGGER BUTTON HOLE 
           131   d  INNER NEEDLE KNOB GROOVE 
           131   e  OUTER NEEDLE KNOB GROOVE 
           132  TRIGGER BUTTON 
           132   a ,  137   a  FULCRUM 
           132   b  INNER NEEDLE FIXING HOOK 
           133  INNER NEEDLE CHARGING COIL SPRING 
           134  INNER NEEDLE SLIDER 
           135  INNER NEEDLE KNOB 
           136  INNER NEEDLE STOPPER 
           137  OUTER NEEDLE FIXING HOOK RELEASE LEVER 
           137   b  OUTER NEEDLE FIXING HOOK 
           138  OUTER NEEDLE CHARGING COIL SPRING 
           139  OUTER NEEDLE SLIDER 
           140  OUTER NEEDLE KNOB 
           141  OUTER NEEDLE STOPPER 
           224  PROJECTION E 
           324 ,  324 A,  424 C CUTOUT PORTION 
           428 ,  428 C RIB