Patent Publication Number: US-2022226665-A1

Title: Light therapy diagnostic device and method for operating the same

Description:
TECHNICAL FIELD 
     The present invention relates to a light therapy diagnostic device used for a treatment method using light such as a photodynamic therapy (PDT) and photo-immunotherapy (PIT) and a method for operating the same. 
     BACKGROUND ART 
     Biomedical treatment methods using light such as PDT and PIT are attracting attention, and as described in the following patent literatures, optical measuring devices that are capable of emitting light for grasping a condition of a treatment site prior to the emission of the light for treatment in a living body are known. 
     Patent Literature 1 discloses an optical probe comprising a tubular probe outer cylinder, an optical waveguide member, a first irradiation unit, and a second irradiation unit. The optical waveguide member guides a first light and a second light disposed in an inner space of the probe outer cylinder in an axial direction of the probe outer cylinder. The first irradiation unit irradiates the first light emitted from a tip of the optical waveguide member while scanning on an irradiation target placed outside the probe outer cylinder. The second irradiation unit enables the second light emitted from the tip of the optical waveguide member to be irradiated on the irradiation target placed outside the prove outer cylinder and on a trajectory of the first light formed on the irradiation target when the first irradiation unit irradiates while scanning. When the first light and the second light are simultaneously emitted from the optical waveguide member, the first irradiation unit and the second irradiation unit irradiate the first light and the second light, respectively, to different parts on the irradiation target. 
     Patent Literature 2 discloses an endoscope system comprising an insertion part, an illumination light irradiation unit, a treatment light irradiation unit, a light receiving unit, and a light intensity detection unit. The insertion part is formed to have a tubular shape that can be inserted into a body cavity of a specimen. The illumination light irradiation unit is provided at a tip part of the insertion part, and is configured to irradiate illumination light for illuminating a subject in the body cavity forward of the tip part. The treatment light irradiation unit is provided integrally with or separately from the tip part, and includes a therapeutic light transmission unit that transmits therapeutic light supplied from a therapeutic light supply unit, and a light diffusing unit that diffuses and irradiates the therapeutic light transmitted by the therapeutic light transmission unit into an substantially tubular region forward of the tip part. The light receiving unit receives a return light of the illumination light emitted forward of the tip part and a return light of the therapeutic light emitted into the substantially tubular region forward of the tip part, respectively. The light intensity detection unit detects an intensity of the return light of the therapeutic light received by the light receiving unit. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1 
     Japanese Unexamined Laid-open Patent Application Publication No. 2008-125939 
     Patent Literature 2 
     Japanese Unexamined Laid-open Patent Application Publication No. 2014-104138 
     SUMMARY OF INVENTION 
     Technical Problem 
     Optical devices used in the apparatuses described in the above patent literatures are all very small in diameter, manufactured using microfabrication technologies such as MEMS, for example. Therefore, the amount of light tends to decrease both in illumination optics that illuminates a surface of a living body and in light receiving optics that receives light returned from the surface of the living body, and there is room for improvement in increasing resolution of an observation image. An object of the present invention is to provide a light therapy diagnostic device that reduces the loss due to reduction in the amount of the light used for biological observation, such as, for example, vignetting and aperture eclipse, and that improves efficiency of light utilization, and a method for operating thereof. 
     Solution to Problem 
     One embodiment of the light therapy diagnostic device of the present invention that has achieved the above object is a light therapy diagnostic device comprising: a catheter shaft having a first end and a second end in a longitudinal direction and a lumen extending in the longitudinal direction; an optical waveguide disposed in the lumen of the catheter shaft and being movable forward and backward in the longitudinal direction; and a transparent member disposed in the lumen of the catheter shaft and located distal to the optical waveguide; wherein: the optical waveguide guides a first light and a second light having a wavelength different from that of the first light; the catheter shaft has a lateral emission window located on a lateral part of the catheter shaft and a distal emission window located on a distal end part of the catheter shaft; the lateral emission window allows the first light and the second light to be emitted toward a lateral direction; the distal emission window allows the first light to be emitted toward a distal direction; the optical waveguide includes a core and a clad, wherein a normal of a distal end surface of the core is inclined with respect to an optical axis of the optical waveguide; the first light passes through the transparent member in a state where the optical waveguide is in contact with the transparent member; and the first light guided through the core is reflected at a distal end part of the optical waveguide in a state where the optical waveguide is apart from the transparent member. In the above light therapy diagnostic device, the transparent member is disposed in the lumen of the catheter shaft, the first light guided through the core is reflected at a distal end part of the optical waveguide in the state where the optical waveguide is apart from the transparent member, and the first light passes through the transparent member in the state where the optical waveguide is in contact with the transparent member, and therefore, efficiency of light utilization can be improved by reducing the loss due to reduction in the amount of the light used for biological observation while having an optical system for light therapy. 
     In the above light therapy diagnostic device, it is preferable that the transparent member is a short optical waveguide having a shorter optical path than the optical waveguide, and a normal of a proximal end surface of the short optical waveguide is inclined with respect to the longitudinal direction of the catheter shaft. 
     In the above light therapy diagnostic device, it is preferable that a proximal part of the optical waveguide is connected to a circumferential rotating member that is configured to stop rotating at a predetermined rotation angle, and a distal end surface of the optical waveguide and a proximal end surface of the short optical waveguide are parallel to each other in a state where the circumferential rotation member is at the predetermined rotation angle. 
     In the above light therapy diagnostic device, it is preferable that the transparent member is made of a material softer than the optical waveguide. 
     In the above light therapy diagnostic device, it is preferable that a distal end surface of the transparent member is perpendicular to the longitudinal direction of the catheter shaft. 
     In the above light therapy diagnostic device, it is preferable that the lateral emission window is disposed over an entire circumference of the catheter shaft. 
     In the above light therapy diagnostic device, it is preferable that a proximal part of the optical waveguide is connected to a circumferential rotating member that rotates the optical waveguide in a circumferential direction of the catheter shaft. 
     In the above light therapy diagnostic device, it is preferable that the optical waveguide includes a first core, a second core disposed outside the first core, and a clad disposed outside the second core, and a refractive index n 1  of the first core, a refractive index n 2  of the second core, and a refractive index n 3  of the clad satisfy the relationship of n 1 &gt;n 2 &gt;n 3 . 
     In the above light therapy diagnostic device, it is preferable that the optical waveguide includes an intermediate clad disposed outside the first core and inside the second core, and the refractive index n 1  of the first core, the refractive index n 2  of the second core, and a refractive index n 4  of the intermediate clad satisfy the relationship of n 1 &gt;n 2 &gt;n 4 . 
     In the above light therapy diagnostic device, it is preferable that the lateral emission window is located at a position corresponding to a non-existent area of the clad. 
     In the above light therapy diagnostic device, it is preferable that the second core has a light diffusion region disposed proximal to the distal end surface of the core. 
     In the above light therapy diagnostic device, it is preferable that surface roughness Ra of an outer surface of the second core in the light diffusion region is larger than surface roughness Ra of an outer surface of the second core in a distal region located distal to the light diffusion region, wherein the surface roughness Ra is determined based on an arithmetic average roughness Ra specified in JIS B 0601 (2001). 
     In the above light therapy diagnostic device, it is preferable that the second core contains light diffusing particles in the light diffusion region. 
     In the above light therapy diagnostic device, it is preferable that a distal end part of the catheter shaft is sharpened. 
     It is preferable that the above light therapy diagnostic device further comprises a light source that generates the first light, and a lens disposed between the light source and the first mirror. 
     In the above light therapy diagnostic device, it is preferable that the catheter shaft includes a balloon connected to the lumen thereof. 
     The present invention also provides a method for operating the above light therapy diagnostic device. One embodiment of a method for operating the light therapy diagnostic device of the present invention comprising the steps of: guiding the first light to the optical waveguide in a state where the core is in contact with the transparent member; guiding the first light to the optical waveguide in a state where the core is apart from the transparent member; and guiding the second light to the optical waveguide to emit the second light from the lateral emission window. 
     Advantageous Effects of Invention 
     According to the above light therapy diagnostic device and its operating method, it is possible to reduce the loss due to reduction in the amount of light used for biological observation while having an optical system for light therapy, and improve efficiency of light utilization. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a lateral view of a light therapy diagnostic device according to an embodiment of the present invention. 
         FIG. 2  shows an enlarged cross-sectional view of a distal part of the light therapy diagnostic device shown in  FIG. 1 , and shows a state in which a first light is emitted toward a lateral direction of the catheter shaft. 
         FIG. 3  shows an enlarged cross-sectional view of the distal part of the light therapy diagnostic device shown in  FIG. 1 , and shows a state in which a first light is emitted toward a distal direction of the catheter shaft. 
         FIG. 4  shows an enlarged cross-sectional view of the distal part of the light therapy diagnostic device shown in  FIG. 1 , and shows a state in which a second light is emitted toward a lateral direction of the catheter shaft. 
         FIG. 5  shows a cross-sectional view of a modified example of the light therapy diagnostic device of  FIG. 2 . 
         FIG. 6  shows a cross-sectional view of a modified example of the light therapy diagnostic device of  FIG. 3 . 
         FIG. 7  shows a cross-sectional view taken along a line VII-VII of the light therapy diagnostic device show in  FIG. 2 . 
         FIG. 8  shows a cross-sectional view of a modified example of the light therapy diagnostic device of  FIG. 7 . 
         FIG. 9  shows a cross-sectional view of a modified example of the light therapy diagnostic device of  FIG. 4 . 
         FIG. 10  shows a cross-sectional view of another modified example of the light therapy diagnostic device of  FIG. 2 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the present invention is specifically explained below based on the following embodiments; however, the present invention is not restricted by the embodiments described below of course, and can be certainly put into practice after appropriate modifications within in a range meeting the gist of the above and the below, all of which are included in the technical scope of the present invention. In the drawings, hatching or a reference sign for a member may be omitted for convenience, and in such a case, the description and other drawings should be referred to. In addition, sizes of various members in the drawings may differ from the actual sizes thereof, since priority is given to understanding the features of the present invention. 
     One embodiment of the light therapy diagnostic device of the present invention is a light therapy diagnostic device comprising: a catheter shaft having a first end and a second end in a longitudinal direction and a lumen extending in the longitudinal direction; an optical waveguide disposed in the lumen of the catheter shaft and being movable forward and backward in the longitudinal direction; and a transparent member disposed in the lumen of the catheter shaft and located distal to the optical waveguide; wherein: the optical waveguide guides a first light and a second light having a wavelength different from that of the first light; the catheter shaft has a lateral emission window located on a lateral part of the catheter shaft and a distal emission window located on a distal end part of the catheter shaft; the lateral emission window allows the first light and the second light to be emitted toward a lateral direction; the distal emission window allows the first light to be emitted toward a distal direction; the optical waveguide includes a core and a clad, wherein a normal of a distal end surface of the core is inclined with respect to an optical axis of the optical waveguide; the first light passes through the transparent member in a state where the optical waveguide is in contact with the transparent member; and the first light guided through the core is reflected at a distal end part of the optical waveguide in a state where the optical waveguide is apart from the transparent member. In the above light therapy diagnostic device, the transparent member is disposed in the lumen of the catheter shaft, the first light guided through the core is reflected at a distal end part of the optical waveguide in the state where the optical waveguide is apart from the transparent member, and the first light passes through the transparent member in the state where the optical waveguide is in contact with the transparent member, and therefore, efficiency of light utilization can be improved by reducing the loss due to reduction in the amount of the light used for biological observation while having an optical system for light therapy. 
     The configuration of the light therapy diagnostic device is explained with reference to  FIGS. 1 to 4 .  FIG. 1  shows a lateral view of a light therapy diagnostic device according to an embodiment of the present invention, and  FIGS. 2 to 4  show enlarged cross-sectional views of a distal part of the light therapy diagnostic device shown in  FIG. 1 .  FIG. 2  represents a state in which a first light is emitted toward a lateral direction of the catheter shaft,  FIG. 3  represents a state in which a first light is emitted toward a distal direction of the catheter shaft, and  FIG. 4  represents a state in which a second light is emitted toward a lateral direction of the catheter shaft. A light therapy diagnostic device  1  comprises a catheter shaft  10 , an optical waveguide  20  and a transparent member  30 . Hereinafter, the light therapy diagnostic device  1  may be simply referred to as a device  1 , and the catheter shaft  10  may be simply referred to as a shaft  10 . 
     The device  1  can be used for PDT and PIT. In the device  1 , an optical coherence tomography (OCT) method is preferably adopted for observing a living tissue by image diagnosis, however, an ultrasonic imaging method or a fluorescence imaging method may be adopted. 
     The shaft  10  has a first end and a second end that define a longitudinal direction. A distal side of the device  1  and the shaft  10  means a first end side in the longitudinal direction of the shaft  10  (in other words, a longitudinal axis direction of the shaft  10 ) and refers to a treatment target side. A proximal side of the light therapy diagnostic device  1  and the shaft  10  means a second end side in the longitudinal direction of the shaft  10  and refers to a hand side of a user (operator). In  FIG. 1 , the left side represents the distal side, and the right side represents the proximal side. Further, in a radial direction of the shaft  10 , an inner side means a direction toward a center of the longitudinal axis of the shaft  10 , and an outer side means a direction opposite to the inner side, namely a radiation direction. 
     The shaft  10  has a lumen  11  extending in the longitudinal direction. The shaft  10  has a tubular structure to dispose an optical waveguide  20  in the lumen  11 . Since the shaft  10  is inserted into a body, it preferably has flexibility. Examples of the tubular structure of the shaft  10  include: a hollow body formed by arranging one or a plurality of wires in a certain pattern; the hollow body of which at least one of an inner surface and an outer surface thereof is coated with a resin; a cylindrical resin tube; and combination thereof (for example, those connected in the longitudinal direction of the shaft  10 ). As the hollow body in which wires are arranged in a certain pattern, a tubular body having a mesh structure by which wires are simply crossed or knitted, or a coil in which a wire is wound is exemplified. The wire may be one or a plurality of single wires, or may be one or a plurality of stranded wires. The resin tube can be manufactured, for example, by extrusion molding. In the case where the shaft  10  is made of a tubular resin tube, the shaft  10  can be composed of a single layer or a plurality of layers. A part of the shaft  10  in the longitudinal direction or a circumferential direction may be composed of a single layer, and another part of that may be composed of a plurality of layers. As shown in  FIG. 1 , a handle  40  gripped by an operator is preferably connected to a proximal part of the shaft  10 . The device  1  may be incorporated in an endoscope or may be used as a combined device. This enables more detailed observation and treatment of a target site. 
     The shaft  10  can be composed of, for example, a synthetic resin such as a polyolefin resin (for example, polyethylene, polypropylene), a polyamide resin (for example, nylon), a polyester resin (for example, PET), an aromatic polyetherketone resin (for example, PEEK), a polyether polyamide resin, a polyurethane resin, a polyimide resin and a fluororesin (for example, PTFE, PFA, ETFE), or a metal such as stainless steel, carbon steel and nickel-titanium alloy. These may be used alone or in combination of two or more. 
     The optical waveguide  20  is disposed in the lumen  11  of the shaft  10  and can move forward and backward in the longitudinal direction of the shaft  10 . The optical waveguide  20  guides a first light  51  and a second light  52  having a wavelength different from that of the first light  51 . Since the optical waveguide  20  is disposed so as to be movable forward and backward in the longitudinal direction of the shaft  10 , it is possible to switch between contact and non-contact between the optical waveguide  20  and the transparent member  30 . The optical waveguide  20  has a core  21  and a clad  23 , and a normal of a distal end surface  22  of the core  21  is inclined with respect to an optical axis of the optical waveguide  20 . Examples of the optical waveguide  20  include an optical fiber. A light source is preferably connected to a proximal part of the optical waveguide  20 . Thereby, the first light  51  and the second light  52  can enter the optical waveguide  20 . 
     By moving the optical waveguide  20  in the lumen  11  of the shaft  10  in the longitudinal direction of the shaft  10 , a position of the optical waveguide  20  relative to the shaft  10  can be changed. Thereby, a user can switch between a lateral observation mode, in which a lateral side of the device  1  is observed by emitting the first light  51  from a lateral emission window  12 , and a forward observation mode, in which a front of the device  1  is observed by emitting the first light  51  from a distal emission window  13 . A risk of the device  1  puncturing a blood vessel can be reduced when puncturing the device  1  into a body by switching it to the forward observation mode. After inserting the device  1  to a predetermined position, a target site can be observed by switching it to the lateral observation mode. 
     It is preferable that the first light  51  is an observation light for grasping a condition of a treatment site or its surrounding site, and the second light  52  is a treatment light. Thereby, both grasping a condition of a treatment site and providing treatment with one device  1  can be conducted, and it is possible to perform diagnosis and treatment at the same time, which has been difficult in the past. By observing a target site with the observation light after irradiation of the treatment light, a result of treatment of the target site can be confirmed. As a result, procedure time and treatment period can be shortened. 
     For the observation of a living tissue by OCT, the first light  51  is preferably near-infrared light, and more preferably infrared light. As a result, passability of the first light  51  to the living tissue is increased. The light source of the first light  51  may be a super luminescent diode light source, a super continuum light source, or a wavelength sweep laser. The wavelength (center wavelength) of the first light  51  may be, for example, 1.3 μm or longer, 1.35 μm or longer, or 1.4 μm or longer, and may also be allowable to be 1.8 μm or shorter, 1.75 μm or shorter, or 1.7 μm or shorter. 
     The second light  52  is preferably a laser beam which irradiates a living tissue and has a wavelength suitable for phototherapy such as PDT and PIT. The wavelength of the second light  52  is preferably shorter than the wavelength of the first light  51 . The wavelength of the second light  52  may be, for example, 0.64 μm or longer, 0.65 μm or longer, or 0.66 μm or longer, and may also be allowable to be 0.72 μm or shorter, 0.71 μm or shorter, or 0.7 μm or shorter. 
     The first light  51  and the second light  52  may be emitted from one light source, or the first light  51  and the second light  52  may be emitted from different light sources from each other. 
     It is preferable that the device  1  comprises a light source  42  that generates the first light  51  and a lens (not shown) disposed between the light source  42  and a distal end surface  22  of the core  21 . The first light  51  can enter the optical waveguide  20  by the light source  42  and the lens focuses the first light  51 , whereby it is possible to obtain an image of a living tissue on a lateral side of the lateral emission window  12  or an image of a living tissue on a distal side of the distal emission window  13 . The lens may be located proximal to the optical waveguide  20 , may be located in the optical waveguide  20 , or may be located distal to the optical waveguide  20 . As the lens, a so-called GRIN lens, which is composed of a continuously changing refractive index, is preferably used. 
     The shaft  10  has the lateral emission window  12  located on a lateral part of the shaft  10  and the distal emission window  13  located on a distal end part of the shaft  10 . The lateral emission window  12  allows the first light  51  and the second light  52  to be emitted toward a lateral direction therefrom, and the distal emission window  13  allows the first light  51  to be emitted toward a distal direction therefrom. By providing the emission windows on the shaft  10  in this manner, the lights can be emitted from the emission windows. 
     The lateral emission window  12  is preferably formed on a sidewall of the shaft  10 . The lateral emission window  12  is preferably disposed so as to extend in a circumferential direction of the shaft  10 , and more preferably disposed over an entire circumference of the shaft  10 . Thereby, the second light  52  can be emitted over a wide area at once, so that a burden on a patient can be reduced. 
     The lateral emission window  12  is preferably located proximal to a distal end of the shaft  10 . A proximal end of the lateral emission window  12  can be placed, for example, within 10 cm from the distal end of the shaft  10 . 
     The distal emission window  13  is preferably formed on a distal end surface of the shaft  10 . This makes it easier to emit the first light  51  toward a distal direction from the distal emission window  13 . The distal end surface of the shaft  10  may be a flat surface or a curved surface. As a result, the distal emission window  13  can also be formed in a flat surface or a curved surface. 
     The lateral emission window  12  and the distal emission window  13  may be made of a material that transmits the first light  51  or the second light  52 . It is preferable that a constituent material of the lateral emission window  12  and the distal emission window  13  has a higher transmittance than a constituent material of a part of the shaft  10  where the emission window is not formed. Regarding the material constituting the lateral emission window  12  and the distal emission window  13 , the description of the constituent materials of the shaft  10  and the below-described transparent material  30  can be referred to. The material constituting the lateral emission window  12  and the distal emission window  13  may be the same or different from each other. 
     As shown in  FIG. 2 , the transparent member  30  is disposed in the lumen  11  of the shaft  10  and is located distal to the optical waveguide  20 . A normal of the distal end surface  22  of the core  21  of the optical waveguide  20  is inclined with respect to the optical axis of the optical waveguide  20 . Therefore, as shown in  FIG. 2 , in the state where the optical waveguide  20  is apart from the transparent member  30 , the first light  51  guided through the core  21  is reflected at a distal end part of the optical waveguide  20 . As a result, the first light  51  can be emitted from the side emission window  12  toward a lateral direction, and so it becomes possible to grasp a condition of a living tissue on a lateral side of the shaft  10 . In OCT, a tomographic image is created based on the reflected light when the first light  51  is irradiated to a living tissue. In detail, the reflection of the first light  51  at the distal end part of the optical waveguide  20  is caused by difference between a refractive index of the core  21  of the optical waveguide  20  and a refractive index of the air present in the lumen  11  of the shaft  10 . For example, when the refractive index of the core  21  is set to 1.45, sin θc=1/1.45=0.6896 according to Snell&#39;s law is derived, since the refractive index of air is about 1, and so the critical incident angle θc comes to be about 43.6°. Therefore, by making the angle between the normal of the distal end surface  22  of the core  21  and the optical axis of the optical waveguide  20  larger than 43.6°, the first light  51  incident on the reflection interface from the core  21  side can be emitted toward a lateral direction through the lateral emission window  12 . The above refractive index indicates are values for light of wavelength 589.3 nm (D ray of sodium). 
     Meanwhile, as shown in  FIG. 3 , in the case where the optical waveguide  20  is in contact with the transparent member  30 , the first light  51  transmits through the transparent member  30 . As a result, the first light  51  can be emitted toward the distal direction from the distant emission window  13 , and so it becomes possible to grasp a condition of a living tissue on a distal side of the device  1 . In detail, it is preferable to set the refractive indexes of the core  21  of the optical waveguide  20  and the transparent member  30  to the same value or close to each other. Since reflection does not occur at the interface between the core  21  and the transparent member  30  when the core  21  and the transparent member  30  are in contact with each other, the first light  51  incident from the core  21  side passes through the transparent member  30 . As a result, the first light  51  can be emitted in the distal direction of the shaft  10 . 
     By making the optical waveguide  20  and the transparent member  30  contact or non-contact as described above, the emission direction of the first light  51  can be easily switched between the lateral direction and the distal direction. Therefore, according to the device  1 , efficiency of light utilization can be improved by reducing the loss due to reduction in the amount of the light used for biological observation while having an optical system for light therapy. 
     As shown in  FIG. 4 , in the state where the optical waveguide  20  is apart from the transparent member  30 , the second light  52  guided through the core  21  is preferably reflected at a distal end part of the optical waveguide  20 . As a result, the second light  52  can be emitted in the lateral direction from the side emission window  12 . By irradiating the second light  52  to a living tissue on a lateral side of the shaft  10 , treatment of living using the light can be performed. 
     The distal end surface  22  of the core  21  is preferably a flat surface. Thereby, in the state where the optical waveguide  20  is apart from the transparent member  30 , the first light  51  guided through the core  21  is easily reflected on the distal end surface  22  of the core  21 . 
     The inclination angle of the normal of the distal end surface  22  of the core  21  with respect to the optical axis of the optical waveguide  20  can be appropriately set in relation with the refractive indexes of the core  21  of the optical waveguide  20  and the transparent member  30 . The inclination angle may be, for example, 40 degrees or larger, 41 degrees or larger, or 42 degrees or larger, and may also be allowable to be 47 degrees or smaller, 46 degrees or smaller, or 45 degrees or smaller. 
     The refractive index of the core  21  of the optical waveguide  20  may be larger than the refractive index of the clad  23 , and may be, for example, 1.4 or more, 1.41 or more, 1.43 or more, or 1.45 or more, and may also be allowable to be 1.7 or less, 1.6 or less, or 1.5 or less. 
     The transparent member  30  may be made of a material which the first light  51  is capable of transmitting. It is preferable that the refractive indexes of the core  21  of the optical waveguide  20  and the transparent member  30  are the same or close to each other. Thereby, in the state where the core  21  of the optical waveguide  20  is in contact with the transparent member  30 , the first light  51  can be reliably emitted in the distal direction. Therefore, the refractive index of the transparent member  30  is preferably 1.4 or more, more preferably  1 . 41  or more, even more preferably 1.43 or more, still even more preferably 1.45 or more, and may be also allowable to be 1.7 or less, 1.6 or less, or 1.5 or less. 
     The transparent material  30  may be made of a material which the first light  51  transmits. The transparent member  30  can be made of a synthetic resin such as (meth)acrylic resin (for example, polymethylmethacrylate (PMMA)), polycarbonate resin (for example, polydiethylene glycol bisallyl carbonate (PC)), polystyrene resin (for example, methyl methacrylate/styrene copolymer resin (MS), acrylonitrile styrene resin (SAN)), polyamide resin (for example, nylon), and polyolefin resin. These may be used alone or in combination of two or more. 
     As shown in  FIGS. 2 to 4 , the transparent member  30  is preferably a resin lump  31 . This makes it easier to place the transparent member  30  inside the shaft  10 . The resin lump  31  preferably closes the lumen  11  of the shaft  10 . Thereby, a contact area is secured when the optical waveguide  20  and the resin lump  31  come into contact. 
     It is preferable that the transparent member  30  is made of a material softer than the optical waveguide  20 . When the optical waveguide  20  and the transparent member  30  come into contact, the transparent member  30  can easily adhere to the optical waveguide  20 , thereby facilitating irradiation of the first light  51  in the distal direction. 
     It is preferable that a distal end surface of the transparent member  30  is perpendicular to the longitudinal direction of the shaft  10 . Thereby, reflection loss of the first light  51  at the distal end surface of the transparent member  30  is suppressed, and the first light  51  is easily emitted in the distal direction. 
       FIGS. 5 and 6  show an example where the transparent member  30  is a short optical waveguide  32 . As shown in  FIG. 5 , the transparent member  30  may be a short optical waveguide  32  having a shorter optical path than the optical waveguide  20 . The short optical waveguide  32  may have a core  33  and a clad  34 . Also by configuring the transparent member  30  in this manner, the emission direction of the first  51  can be easily switched. For example, as shown in  FIG. 5 , in the state where the optical waveguide  20  and the short optical waveguide  32  (in detail, the core  21  of the optical waveguide  20  and the core  33  of the short optical waveguide  32 ) are separated from each other, the first light  51  guided through the core  21  is reflected at the distal end part of the optical waveguide  20 . Also, as shown in  FIG. 6 , in the state where the optical waveguide  20  and the short optical waveguide  32  are in contact with each other, the optical waveguide  20  and the short optical waveguide  32  function as one waveguide, and so it becomes possible to emit the first light  51  in the distal direction. 
     It is preferable that a normal of a proximal end surface  35  of the short optical waveguide  32  is inclined with respect to the longitudinal direction of the shaft  10 . This makes it easier to bring the distal end surface  22  of the core  21  of the optical waveguide  20  into contact with the proximal end surface  35  of the short optical waveguide  32 . As a result, it becomes easy to connect the optical waveguide  20  to the short optical waveguide  32 , and the first light  51  is easily emitted in the distal direction. 
     In the state that the device  1  is viewed from the longitudinal direction of the shaft  10 , it is preferable that the core  21  of the optical waveguide  20  and the core  33  of the short optical waveguide  32  are arranged so as to overlap with each other, and more preferably, the optical axis of the short optical waveguide  32  is arranged so as to overlap with the optical axis of the optical waveguide  20 . Thereby, when the optical waveguide  20  is brought into contact with the short optical waveguide  32 , the first light  51  can easily enter the short optical waveguide  32  from the optical waveguide  20 . 
     As shown in  FIGS. 2 to 6 , the transparent member  30  is preferably disposed in contact with the distal emission window  13 , but may be disposed adjacent to the distal emission window  13 . 
     The configuration of the optical waveguide  20  is explained with reference to  FIGS. 7 to 8 . The optical waveguide  20  may have one or more single-core fibers in which one core is disposed in one clad, or may have one or more multi-core fibers in which a plurality of cores are disposed in one clad. 
     As shown in  FIG. 7 , the optical waveguide  20  preferably includes a first core  21 A, a second core  21 B disposed outside the first core  21 A, and a clad  23  disposed outside the second core  21 B. Here, a refractive index n 1  of the first core  21 A, a refractive index n 2  of the second core  21 B, and a refractive index n 3  of the clad  23  satisfy the relationship of n 1 &gt;n 2 &gt;n 3 . By disposing the second core  21 B on an outer circumference of the first core  21 A in this manner, the second light  52  can be easily emitted from the entire circumference of the shaft  10 , so that it can be emitted over a wide range at once. The first core  21 A, the second core  21 B and the clad  23  are preferably arranged concentrically. As a result, the first light  51  can be guided by the first core  21 A, and the second light  52  can be guided by the first core  21 A and the second core  21 B, while the clad  23  prevents the lights from leaking. 
       FIG. 8  shows a cross-sectional view of a modified example of the optical waveguide  20  shown in  FIG. 7 . As shown in  FIG. 8 , the optical waveguide  20  preferably includes an intermediate clad  24  disposed outside the first core  21 A and inside the second core  21 B. Here, the refractive index n 1  of the first core  21 A, the refractive index n 2  of the second core  21 B, and a refractive index n 4  of the intermediate clad  24  satisfy the relationship of n 1 &gt;n 2 &gt;n 4 . Thereby, the light guided by the first core  21 A can be confined by the intermediate clad  24 , and the light guided by the second core  21 B can be confined by the intermediate clad  24  and the clad  23 . As a result, leakage of the light from the optical waveguide  20  can be prevented. The refractive index n 4  of the intermediate clad  24  may be the same as or different from the refractive index n 3  of the clad  23 . 
       FIG. 9  shows a cross-sectional view of a modified example of the device  1  of  FIG. 4 . As shown in  FIG. 9 , the lateral emission window  12  is preferably located at a position corresponding to a non-existing region  23   a  of the clad  23 . Thereby, the first light  51  or the second light  52  guided by core  21  can be emitted toward the lateral direction from the non-existing region  23   a  of the clad  23 . Specifically, it is preferable that the second light  52  is emitted toward the lateral direction from the non-existing region  23   a  of the clad  23 . That the lateral emission window  12  is located at a position corresponding to the non-existing region  23   a  of the clad  23  means that the non-existing region  23   a  of the clad  23  and the lateral emission window  12  of the shaft  10  overlaps with each other at least in part when the optical waveguide  20  is located at a certain position of the shaft  10 . 
     The non-existing region  23   a  of the clad  23  is a region in which the core  21  (the first core  21 A or the second core  21 B, preferably the second core  21 B) inside the clad  23  is exposed to the outside due to the absence of the clad  23 . Examples of a method of forming the non-existing region  23   a  of the clad  23  in this manner include a method of mechanically or chemically removing the clad  23 , and for example, laser processing and etching processing are mentioned. 
     The non-existing region  23   a  of the clad  23  is preferably disposed so as to extend in the circumferential direction, and more preferably disposed over the entire circumference of the optical waveguide  20 . Thereby, the second light  52  can be emitted over a wide area at once. 
     As shown in  FIG. 9 , the second core  21 B preferably has a light diffusion region  21 Ba proximal to the distal end surface  22  of the core  21 . By providing the light diffusion region  21 Ba in the second core  21 B in this manner, the second light  52  can be suitably diffused, so that the second light  52  can be emitted over a wide range at once. 
     It is preferable that the surface roughness Ra of an outer surface of the second core  21 B in the light diffusion region  21 Ba is larger than the surface roughness Ra of an outer surface of the second core  21 B in a distal region distal to the light diffusion region  21 Ba. Here, the surface roughness Ra is determined based on an arithmetic average roughness Ra specified in JIS B 0601 (2001). By setting the surface roughness in this manner, the second light  52  can be efficiently diffused from the light diffusion region  21 Ba, so that it can be emitted over a wide range at once. 
     Examples of a method of roughening the outer surface of the second core  21 B in the light diffusion region  21 Ba include a method of mechanically or chemically roughening the surfaces, and for example, etching, blasting, scribing, wire-brushing, a method of using sandpaper, and the like are mentioned. 
     It is preferable that the second core  21 B contains light diffusing particles in the light diffusion region  21 Ba. Thereby, the second light  52  can be efficiently diffused in the light diffusion region  21 Ba, so that it can be emitted over a wide range at once. Examples of the light diffusing particles include inorganic particles such as titanium oxide, barium sulfate and calcium carbonate, and organic particles such as crosslinked acrylic particles and crosslinked styrene particles. 
     It is preferable that the length of the light diffusion region  21 Ba of the second core  21 B or the length of the non-existing region  23   a  of the clad  23  in the longitudinal direction of the shaft  10  is shorter than that of the lateral emission window  12 . This makes it easier to emit the second light  52  toward the lateral direction of the shaft  10  without loss. 
     As shown in  FIGS. 2 to 6 , it is preferable that a distal end of the shaft  10  is closed. Thereby, liquids such as body fluids are prevented from entering the lumen  11  of the shaft  10 . A normal of a distal end surface of the shaft  10  may be parallel to the optical axis of the optical waveguide  20 . 
     Although it is not shown in the drawings, the shaft  10  may be composed of a plurality of members. For example, the shaft  10  may include a cylindrical shaft body having an opening at a distal end thereof, and a cap provided at a distal end part of the shaft body and closing the opening of the shaft body. In that case, the distal emission window  13  may be formed on the cap. Thereby, a part of the distal emission window  13  and the shaft  10 , where the emission window is not formed, can be easily composed of a different material. Regarding a material constituting the cap, the description of the constituent material of the shaft  10  can be referred to. 
       FIG. 10  shows a cross-sectional view of a modified example of the device  1  of  FIG. 2 . As shown in  FIG. 10 , in a cross section along the longitudinal direction of the shaft  10 , a distal end part of the shaft  10  may be formed in a sharp shape formed by one line or may be formed in a sharp shape formed by two or more lines. A distal end of the shaft  10  may be located at an outer end of the shaft  10  in a radial direction or may be located at a center of the longitudinal axis of the shaft  10 . In this manner, it is preferable that the distal end part of the shaft  10  is sharpened. Since the distal end part of the shaft  10  can be punctured into a tissue, a position of the shaft  10  in a body can be fixed. As a result, it becomes easy to emit the first light  51  and the second light  52  for image diagnosis and treatment. 
     As shown in  FIG. 1 , a proximal part of the optical waveguide  20  is preferably connected to a circumferential rotating member  41  that rotates the optical waveguide  20  in the circumferential direction of the shaft  10 . More preferably, the optical waveguide  20  rotates with respect to the shaft  10  around its optical axis. Since the optical waveguide  20  can be rotated around its optical axis, the emission position of the light from the lateral emission window  12  in the circumferential direction of the shaft  10  can be adjusted. 
     It is preferable that the proximal part of the optical waveguide  20  is connected to the circumferential rotating member  41 , the circumferential rotating member  41  is configured to stop rotating at a predetermined rotation angle, and the distal end surface of the optical waveguide  20  (preferably the distal end surface  22  of the core  21 ) and the proximal end surface  35  of the short optical waveguide  32  come to be parallel to each other in the state where the circumferential rotating member is at the predetermined rotation angle. By rotating the circumferential rotating member  41 , it is possible to switch between contact and non-contact between the optical waveguide  20  and the short optical waveguide  32 . In addition, by forming the distal end surface of the optical waveguide  20  and the proximal end surface  35  of the short optical waveguide  32  parallel to each other, it becomes easy to bring the optical waveguide  20  into contact with the short optical waveguide  32 . 
     Although it is not shown in the drawings, the shaft  10  may be provided with a balloon on a distal part thereof. In particular, the shaft  10  may include a balloon connected to the lumen thereof. The balloon may be located so as to cover the lateral emission window  12  or may be located distal to or proximal to the lateral emission window  12 , in relation to the lateral emission window  12  provided on the shaft  10 . Alternatively, the balloon may cover the distal emission window  13  or both the lateral emission window  12  and the distal emission window  13 . It is preferable that the balloon is attached to the shaft  10  so that an attaching part of the balloon to the shaft  10  does not overlap with the lateral emission window  12  and the distal emission window  13 . In the case where the light can pass through the balloon, the balloon may be attached to the shaft  10  so as to overlap with the lateral emission window  12 . By providing the balloon on the shaft  10 , the device  1  can be fixed in a body cavity, and the light can be stably emitted from the lateral emission window  12 . In the case where the balloon is arranged on the shaft  10  so as to cover the lateral emission window  12 , the balloon is preferably made of a highly transparent material to prevent attenuation of the light emitted from the lateral emission window  12 . 
     Each of the above preferred embodiments can be combined as necessary to form a part of the configuration of the light therapy diagnostic device of the present invention. 
     The present invention also provides a method for operating the above light therapy diagnostic device  1 . One embodiment of the method for operating the light therapy diagnostic device  1  of the present invention comprises steps of: guiding the first light  51  to the optical waveguide  20  in the state where the core  21  is in contact with the transparent member  30 ; guiding the first light  51  to the optical waveguide  20  in the state where the core  21  is apart from the transparent member  30 ; and guiding the second light  52  to the optical waveguide  20  to emit the second light  52  from the lateral emission window  12 . 
     The first light  51  is guided to the optical waveguide  20  in the state where the core  21  is in contact with the transparent member  30 . Thereby, the first light  51  can be emitted from the distal emission window  13  toward a distal direction, and therefore, a condition of a living tissue located on a distal side of the device  1  can be grasped. 
     The first light  51  is guided to the optical waveguide  20  in the state where the core  21  is apart from the transparent member  30 . Thereby, the first light  51  can be emitted from the lateral emission window  12  toward a lateral direction, and therefore, a condition of a living tissue located on a lateral side of the device  1  can be grasped. 
     The second light  52  is guided to the optical waveguide  20  and the second light  52  is emitted from the lateral emission window  12 . Thereby, the second light  52  can be emitted to a tissue located on a lateral side of the shaft  10 , and therefore, treatment of living using the light can be conducted. 
     This application claims priority to Japanese Patent Application No. 2019-109903, filed on Jun. 12, 2019. All of the contents of the Japanese Patent Application No. 2019-109903, filed on Jun. 12, 2019, are incorporated by reference herein. 
     REFERENCE SIGNS LIST 
       1 : light therapy diagnostic device 
       10 : catheter shaft 
       11 : lumen 
       12 : lateral emission window 
       13 : distal emission window 
       20 : optical waveguide 
       21 : core 
       21 A: first core 
       21 B: second core 
       21 Ba: light diffusion region 
       22 : distal end surface of core 
       23 : clad 
       23   a:  non-existent region of clad 
       24 : intermediate clad 
       30 : transparent member 
       31 : resin lump 
       32 : short optical waveguide 
       33 : core of short optical waveguide 
       34 : clad of short optical waveguide 
       35 : proximal end surface of short optical waveguide 
       40 : handle 
       41 : circumferential rotating member 
       42 : light source 
       51 : first light 
       52 : second light