JP2012081048A - Electronic endoscope system, electronic endoscope, and excitation light irradiation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily carry out AFI (auto fluorescence imaging) without a cost increase even in an electronic endoscope system having only an ordinary light observing function.SOLUTION: The electronic endoscope includes an overtube 13 mounted to the insertion part, and a hood 14 mounted to the tip part. The overtube 13 is provided with first and second optical fibers 38, 39 guiding excitation light emitted from an excitation light source device. First and second light projection units 41, 42 irradiating excitation light toward the body cavity are fixed to the outer peripheral surface of the hood 14. Self-fluorescence is emitted from living tissue in the body cavity by the irradiation of excitation light. Since the overtube 13, the hood 14, the first and second projection units 41, 42 and the excitation light source device are externally fitted to the electronic endoscope, AFI can be easily carried out without the cost increase.

Description

  The present invention relates to an electronic endoscope system, an electronic endoscope, and an excitation light irradiation method for observing autofluorescence emitted from a living tissue in a body cavity.

  In the medical field in recent years, many diagnoses and treatments using an electronic endoscope system have been performed. In an electronic endoscope system, white light having a wavelength ranging from a blue band to a red band is irradiated in a body cavity, and light reflected in the body cavity is imaged by an imaging element such as a CCD. Then, an image obtained by imaging is displayed on the monitor. Thereby, since the image in a body cavity can be confirmed in real time, a diagnosis etc. can be performed reliably.

  Although the entire subject tissue can be roughly grasped from the captured image obtained by irradiating with white light, the microscopic blood vessels, deep blood vessels, pit patterns (gland opening structure), uneven structures such as depressions and bumps, etc. The subject tissue may be difficult to observe clearly. Since there is a possibility that a lesioned part is hidden in such a subject tissue, there is a demand for reliably grasping a fine blood vessel, a depression, a bulge, and the like from a captured image.

  For example, as a method for observing neoplastic lesions such as cancer, as shown in Patent Document 1, excitation light limited to a specific wavelength is irradiated into a body cavity, and from the endogenous fluorescent substance in living tissue by the excitation light. AFI (Auto Fluorescence Imaging) is known in which auto-fluorescence emitted is imaged by an image sensor. In this AFI, taking advantage of the property that the intensity of autofluorescence emitted from a lesion having a neoplastic lesion is weaker than the intensity of autofluorescence emitted from a normal part where there is no tumorous lesion, The part and normal part are displayed in different colors. As a result, it is possible to observe even a lesion that is almost indistinguishable from a normal part.

JP 2009-34224 A

  However, in many medical facilities, an electronic endoscope system having only a normal light observation function using white light is still common, and an electronic endoscope system equipped with an AFI as shown in Patent Document 1 is so widespread. Not. Therefore, it is desired to enable AFI to be performed easily and without cost even in an electronic endoscope system having only a normal light observation function.

  For example, in Patent Document 1, since the self-fluorescence becomes weak when the amount of excitation light is insufficient, the excitation light is separated from the normal illumination window that irradiates the tip of the electronic endoscope with white light or excitation light. A dedicated illumination window is provided, and excitation light is irradiated from each of these two illumination windows so that sufficient excitation light strikes the living tissue. However, an illumination window dedicated to the excitation light is provided at the tip of the electronic endoscope, or a light guide that guides the excitation light to the illumination window dedicated to the excitation light is incorporated in the insertion part of the electronic endoscope. It is extremely expensive to do.

  The present invention has been made in view of the above problems, and an electronic endoscope that can perform AFI simply and without cost even in an electronic endoscope system having only a normal light observation function. An object is to provide a system, an electronic endoscope, and an excitation light irradiation method.

  In order to achieve the above object, an electronic endoscope system of the present invention includes an excitation light source device that emits excitation light for exciting fluorescence from a living tissue in a body cavity, and an insertion portion that is inserted into the body cavity. An electronic endoscope having, an overtube through which an insertion portion of the electronic endoscope is inserted, an excitation light light guide member that is provided in the overtube and guides excitation light emitted from the excitation light source device; A light projecting unit for irradiating the excitation light guided by the excitation light guide member into the body cavity is provided.

  The electronic endoscope is provided at a distal end portion of the insertion portion, and cuts light including an observation window that receives light reflected in the body cavity and light having a wavelength band of excitation light from light before entering the observation window. It is preferable that the hood for mounting | wearing with the front-end | tip part which has an excitation light cut filter is provided, and the said light projection unit is being fixed to the outer peripheral surface of the hood.

  The light projecting unit preferably has two first and second light projecting units provided at symmetrical positions with respect to the observation window. The light projecting unit is provided in the vicinity of the first light projecting unit, and a third light projecting unit in which an excitation light irradiation range is different from an excitation light irradiation range in the first light projecting unit, and the second light projecting unit It is preferable to further include a fourth light projecting unit which is provided in the vicinity of the unit and whose excitation light irradiation range is different from the excitation light irradiation range in the second light projection unit.

  In each light projecting unit, it is preferable that the irradiation range of the excitation light in each light projecting unit is made different by incorporating different light diffusing members, lenses, and protective glasses. It is preferable to include a switching unit that switches the optical path of the excitation light in the light source device of the excitation light so that the excitation light is emitted from a predetermined light projection unit among the first to fourth light projection units.

  The electronic endoscope has an irradiation window that is provided at a distal end portion of the insertion portion and irradiates white light with a wavelength ranging from a blue band to a red band toward a body cavity, and the irradiation range of the excitation light is It is preferable to be within the irradiation range of white light. The light quantity ratio between the excitation light and the white light is preferably kept constant.

  The white light is preferably surface-sequential light that is irradiated in a time-division manner with R light, G light, and B light. The white light is preferably light that is excited and emitted from the phosphor when irradiated with blue light having a specific wavelength.

  The present invention relates to an electronic endoscope connected to a light source device of excitation light that emits excitation light for exciting fluorescence from a living tissue in a body cavity, and an insertion portion inserted into the body cavity and the insertion portion are inserted An overtube, an excitation light guide member that guides the excitation light emitted from the excitation light source device, and the excitation light guided by the excitation light guide member is directed into the body cavity. And a light projecting unit for irradiating.

  The present invention is an excitation that uses an excitation light source device that emits excitation light for exciting fluorescence from biological tissue in a body cavity, and an electronic endoscope in which an insertion portion that is inserted into the body cavity is inserted through an overtube. In the light irradiation method, the excitation light emitted from the excitation light source device is guided by the excitation light guide member provided in the overtube, and the guided excitation light is directed from the light projecting unit into the body cavity. Irradiating.

  According to the present invention, an excitation light guide member for guiding excitation light for exciting fluorescence such as autofluorescence is provided on an overtube external to the electronic endoscope, and the excitation light Since the light projection unit for irradiating the body cavity with the excitation light guided by the optical member is provided externally to the electronic endoscope in the same manner as the overtube, only the normal light observation function is provided. Even in the electronic endoscope system, the AFI can be performed simply and without cost by simply attaching an excitation light source device, an overtube, a light projecting unit, and the like.

It is the schematic which shows the electronic endoscope system of 1st Embodiment. It is a block diagram which shows the electric constitution in the electronic endoscope system of 1st Embodiment. It is a graph which shows the spectral intensity distribution of excitation light, autofluorescence, and white light. It is a perspective view which shows the front-end | tip part of the electronic endoscope of 1st Embodiment with which the overtube and the hood were mounted | worn. It is explanatory drawing for demonstrating the irradiation range of white light. It is explanatory drawing for demonstrating a rotary shutter when it exists in a white light irradiation period. It is explanatory drawing for demonstrating a rotary shutter when it exists in a white light shielding period. It is explanatory drawing for demonstrating the method to control the light quantity of excitation light according to the light quantity of white light. It is explanatory drawing for demonstrating the irradiation range of excitation light. It is sectional drawing of the 1st light projection unit for excitation light irradiation. It is explanatory drawing for demonstrating the imaging control of CCD in normal light observation mode. It is explanatory drawing for demonstrating the imaging control of CCD in autofluorescence observation mode. It is a block diagram which shows the processing flow in a signal processing part. It is a block diagram which shows the electric constitution in the electronic endoscope system of 2nd Embodiment. It is a perspective view which shows the front-end | tip part of the electronic endoscope of 2nd Embodiment with which the overtube and the hood were mounted | worn. It is a top view of the rotary filter used for irradiation of the field sequential light of RGB. It is a block diagram which shows the electric constitution of the electronic endoscope system in another embodiment. It is sectional drawing of the light projection unit for white light irradiation.

  As shown in FIG. 1, an electronic endoscope system 10 according to a first embodiment of the present invention includes an electronic endoscope 11 that captures an image of a body cavity of a subject using an image sensor such as a CCD, and the electronic endoscope. 11, an overtube 13 through which the insertion portion 20 is inserted, a hood 14 attached to the distal end portion 24a of the insertion portion 20, and a processor device that generates an image of a subject tissue in a body cavity based on a signal obtained by imaging 15, a white light source device 16 that supplies white light to be irradiated into the body cavity, an excitation light source device 17 that supplies excitation light for exciting autofluorescence from within the living tissue, and an image in the body cavity. And a monitor 18 for display.

  The electronic endoscope 11 includes a flexible insertion portion 20 to be inserted into a body cavity, an operation portion 21 provided at a proximal end portion of the insertion portion, an operation portion 21, a processor device 15, and a white light source device. 16 is provided with a universal cord 23 that connects the two. A bending portion 24 is formed at the distal end of the insertion portion 20 by connecting a plurality of bending pieces. The bending portion 24 bends in the up / down / left / right directions by the operation of the angle knob 26 of the operation portion.

  At the distal end of the bending portion 24, a distal end portion 24a incorporating an optical system for in-vivo imaging is provided. The distal end portion 24 a is directed in a desired direction within the body cavity by the bending operation of the bending portion 24. The distal end portion 24a has two first and second illumination windows 57 and 59 (see FIG. 4) that emit white light and excitation light, and an observation window 62 (see FIG. 4) that receives white light and autofluorescence from inside the body cavity. 4), an air supply / water supply nozzle 63 (see FIG. 4) for blowing water or air toward the observation window, and a forceps outlet 64 (see FIG. 4) serving as an outlet of the treatment instrument inserted into the forceps channel in the insertion portion 20. 4).

  The operation unit 21 switches the observation mode to either a normal light observation mode for observing the body cavity using white light or an autofluorescence observation mode for observing autofluorescence emitted from the living tissue using excitation light. A button 28 is provided. Switching information by the observation mode switching button 28 is transmitted to the controller 113 (see FIG. 2) of the processor device.

  Here, when the normal light observation mode is set, a white light image obtained by imaging the white light reflected in the body cavity is displayed on the monitor 18 and the auto fluorescence observation mode is set. The monitor 18 displays an autofluorescence image obtained by imaging autofluorescence or a composite image obtained by synthesizing a white light image and an autofluorescence image.

  A connector 30 is attached to the end of the universal cord 23 on the processor device 15 and white light source device 16 side. The connector 30 is a composite type connector composed of a communication connector and a light source connector, and the electronic endoscope 11 is detachably connected to the processor device 15 and the white light source device 16 through the connector 30. The

  A hood 14 including an excitation light cut filter 32 is attached to the distal end portion 24 a of the electronic endoscope 11. The excitation light cut filter 32 covers or covers the observation window 62 (see FIG. 4) provided at the distal end portion 24a, thereby cutting or reducing the light in the wavelength band of the excitation light out of the light before entering the observation window 62. . The excitation light with very high energy is cut in front of the observation window 62 so that the excitation light does not enter the CCD 100 (see FIG. 2) provided on the back side of the observation window 62. It is possible to prevent halation in which the screen becomes white due to the charge saturation.

  The overtube 13 is provided in the tube main body 35, the endoscope main passage 35, the endoscope insertion conduit 37 through which the insertion portion 29 of the electronic endoscope 11 is inserted, and the endoscope insertion conduit 37. Two first and second optical fibers 38 and 39 that are provided around and guide light of excitation light from the light source device 17 of excitation light are provided.

  The endoscope insertion conduit 37 includes a proximal end opening 37 a serving as an insertion port of the insertion unit 20 of the electronic endoscope and a distal end opening 37 b serving as an outlet of the insertion unit 20. Therefore, when the insertion portion 20 is inserted through the endoscope insertion conduit 37, the distal end portion 24a of the electronic endoscope and the hood 14 attached to the distal end portion 24a are exposed from the distal end side opening 37b. When inserting the insertion portion 20 of the electronic endoscope into the body cavity, the insertion portion 20 is inserted through the overtube 13.

  First and second light projecting units 41 and 42 for irradiating the body cavity with excitation light from the first and second optical fibers 38 and 39 are fixed to the outer peripheral surface of the hood 14. In Patent Document 1, in order to increase the amount of excitation light, irradiation is performed with two excitation lights of assist excitation light in addition to normal excitation light. It is necessary to provide a light guide dedicated to assist excitation light and an illumination window dedicated to assist excitation light at the insertion portion of the endoscope.

  On the other hand, in the present invention, the first and second optical fibers for irradiating two excitation lights on the hood externally attached to the electronic endoscope, not inside the insertion portion of the electronic endoscope. In addition, since the first and second light projecting units are provided, the cost required for the irradiation of the two excitation lights can be suppressed as compared with Patent Document 1. Further, in the present invention, since the forceps channel serving as an insertion path for various treatment tools is not used for the installation of the optical fiber used for the excitation light irradiation or the light projecting unit, Treatment or the like can be performed using various treatment tools inserted into the.

  As shown in FIG. 2, a white light source device 16, a white light source 45, an aperture adjustment mechanism 46, a white light control unit 47, a rotary shutter 48, a position detection unit 49, and a rotation control unit 50 are provided. The white light source 45 is always turned on to emit white light when the power source of the white light source device 16 is on. White light is broadband light having a wavelength ranging from a blue band to a red band, and has a wavelength band of 400 nm to 700 nm as shown in FIG. 3, for example. As the white light source 45, for example, a xenon lamp, a halogen lamp, an LED (light emitting diode), a fluorescent light emitting element lamp, or an LD (laser diode) is used. White light emitted from the white light source 45 is collected by the lens 53. The light condensed by the lens 53 is incident on the first and second light guides 55 and 56 via the aperture adjustment mechanism 46.

  The first and second light guides 55 and 56 are constituted by large-diameter optical fibers or the like. The incident side end portions of the first and second light guides 55 and 56 are connected to the light source device 16 for white light. On the other hand, as shown in FIG. 4, the emission side end of the first light guide 55 is directed to the first illumination window 57 of the distal end portion 24 a of the electronic endoscope 11, and the emission side end of the second light guide 55. Is directed to the second illumination window 59 of the tip 24a. White light is emitted from the first and second illumination windows 57 and 59 toward the body cavity.

  The first illumination window 57 and the second illumination window 59 are provided at symmetrical positions with respect to the excitation light cut filter 32 (or the observation window 62) provided in the hood 14. Further, as shown in FIG. 5, the irradiation range WL1 of white light emitted from the first illumination window 57 and the irradiation range WL2 of white light emitted from the second illumination window 59 substantially overlap each other. Therefore, when the distal end portion 24a is directed to the observation target T, the observation target T substantially enters the overlapping region WLR of the irradiation ranges WL1 and WL2. Thereby, it is possible to irradiate the observation target T with white light sufficiently and without uneven illumination.

  The hood 14 covers only the observation window 62 in the distal end portion 24a, and the other portions are exposed from the opening portion 14a into the body cavity. Therefore, the hood 14 does not prevent the white light from being emitted from the first and second illumination windows 57 and 59. Further, air or water from the air / water supply nozzle 63 can be blown to the excitation light cut filter 32 of the hood. Furthermore, the treatment tool can be protruded from the forceps outlet 64 into the body cavity.

  As shown in FIG. 2, the aperture adjustment mechanism 46 is disposed between the lens 53 and the rotary shutter 48 and adjusts the amount of white light emitted from the white light source 45. The aperture adjusting mechanism 46 is composed of, for example, a plurality of aperture blades that vary the aperture diameter, and a motor that moves the aperture blades. The aperture amount of the aperture adjustment mechanism (that is, the amount of white light) is controlled by the white light control unit 47 via the driver 47a. The white light control unit 47 controls the aperture amount (that is, the amount of white light) based on the white light image obtained by the signal processing in the processor device 15.

  As shown in FIGS. 6A and 6B, the rotary shutter 48 has a disk shape and has a sector-shaped cutout part. Of the rotary shutter 48, the cutout portion is a light transmission portion 48a that transmits white light, and the remaining portion is a light shielding portion 48b that blocks white light. The rotary shutter 48 is connected to a rotation shaft 70 a of a motor 70 that is arranged in parallel with the optical axis of the white light source 45. When the rotary shutter 48 is rotated by driving the motor 70, the light transmitting portions 48a and the light shielding portions 48b are alternately positioned on the optical path P of the white light source.

  Which of the light transmission part 48a and the light shielding part 48b is located on the optical path P is detected by a position detection part 49 constituted by a photosensor or the like. Here, in FIGS. 2 and 6A and 6B, the position detection unit is arranged in the vicinity of the outer periphery of the rotary shutter, but the arrangement position may be other than that, for example, inside the rotary shutter.

  As shown in FIG. 6A, while the light transmitting portion 48a is positioned on the optical path P, white light is incident on the first and second light guides 55 and 56, so that white light is irradiated into the body cavity. This period is a white light irradiation period below. On the other hand, as shown in FIG. 6B, while the light shielding portion 48b is positioned on the optical path P, white light is not incident on the first and second light guides 55 and 56, so that the white light is shielded in the body cavity. It becomes. This period is hereinafter referred to as a white light blocking period. The position detection unit 49 appropriately transmits information on whether the white light irradiation period or the white light blocking period is present to the excitation light control unit 75 in the excitation light source device and the controller 113 of the processor device.

  The white light irradiation period and the white light blocking period differ depending on the observation mode, and each period in the autofluorescence observation mode is set to twice that in the normal light observation mode. Therefore, the rotation control unit 50 shown in FIG. 2 performs rotation control so that the rotation speed of the rotary shutter 48 is half of the rotation speed in the normal light observation mode in the auto fluorescence observation mode. The rotation control unit 50 controls the rotation speed of the rotary shutter 48 via a driver 50 a connected to the motor 70.

  As shown in FIG. 2, the excitation light source device 17 includes first and second laser light sources 72 and 73 and an excitation light control unit 75. The first and second laser light sources 72 and 73 are composed of light emitting diodes and the like, and emit excitation light having a wavelength of 405 ± 10 nm as shown in FIG. By irradiating the body cavity with excitation light having such a wavelength range, autofluorescence having a wavelength of 420 nm to 650 nm is emitted from the endogenous fluorescent substance in the living tissue.

  When the first and second laser light sources 72 and 73 are set to the autofluorescence observation mode, excitation light is always emitted. Thereby, autofluorescence is always emitted from the living tissue. As shown in FIG. 3, the excitation light returning to the distal end portion 24a of the electronic endoscope is cut by an excitation light cut filter, and the amount of autofluorescence is weaker than that of white light. Therefore, even if a white light image is acquired in a state where not only white light but also excitation light and autofluorescence exist in the body cavity, the excitation light and autofluorescence do not affect the acquired white light image at all.

  The excitation light control unit 75 controls the amount of excitation light of the first and second laser light sources 72 and 73 via the drivers 75a and 75b. The excitation light control unit 75 is connected to the white light control unit 47 and controls the amount of excitation light according to the white light amount control by the white light control unit 47. The amount of excitation light is controlled so that the white light and the excitation light have a predetermined correlation, for example, the ratio of the amount of excitation light to the amount of white light is maintained at 1/10. Change the amount of light.

  Even if the amount of white light is changed in this way, the amount of excitation light is automatically changed by the excitation light control unit following this, so the white light image and the autofluorescence image The exposure balance can always be maintained in an appropriate state. In addition, the light amount control of the excitation light is not performed in conjunction with the light amount control of the white light, but when the white light irradiation period is switched to the white light shielding period as shown in FIG. The excitation light may be controlled to have a predetermined correlation.

  The excitation light emitted from the first laser light source 72 enters the first optical fiber 38 of the overtube. The excitation light emitted from the other second laser light source 73 is incident on the second optical fiber 39 of the overtube. As shown in FIG. 4, the excitation light EL in the first optical fiber 38 is emitted from the first light projection unit 41 of the hood 14, and the excitation light EL in the second optical fiber is emitted from the second light projection of the hood 14. The light is emitted from the unit 42.

  The first and second light projecting units 41 and 42 are respectively symmetrical with respect to the excitation light cut filter 32 (or the observation window 62) of the hood 14 similarly to the first and second illumination windows 57 and 59 of the distal end portion 24a. In the position. Further, as shown in FIG. 8, the irradiation range EL1 of the excitation light emitted from the first light projecting unit 41 and the irradiation range EL2 of the excitation light emitted from the second light projection unit 42 substantially overlap (overlapping). Area ELR). Further, the overlapping area ELR is included in the overlapping area WLR in which the two white light irradiation ranges overlap.

  Since the irradiation ranges EL1 and EL2 are as described above, the observation target T almost enters the overlapping area ELR of the irradiation ranges EL1 and EL2 when the distal end portion 24a is directed to the observation target T. Thereby, it is possible to irradiate the observation target T with excitation light sufficiently and without illumination unevenness. Therefore, for example, when the entire observation target T is a normal part, autofluorescence with substantially the same intensity is emitted from the entire area of the observation target. Furthermore, since the overlap area ELR where the two excitation light irradiation ranges overlap is included in the overlap area WLR of the two white light irradiation ranges, the amount of white light and excitation light in the entire observation target T The ratio is kept constant.

  As shown in FIG. 9, the first light projecting unit 41 includes a light diffusing member 90, a cylindrical sleeve member 91 that covers the outer periphery of the light diffusing member, and a protective glass 92 that seals one end of the sleeve member 91. And a ferrule 93 that is inserted into the sleeve member and holds the first optical fiber 38. In addition, a flexible sleeve 95 that covers the outer side of the outer sheath is inserted between the sleeve member 91 and the first optical fiber 38 that is covered with the outer shell and extends from the rear end side of the ferrule 93. Since the second light projecting unit is the same as the first light projecting unit, description thereof is omitted.

  The light diffusing member 90 is made of a translucent resin material that diffuses excitation light from the first optical fiber 38. In addition to the translucent resin material, for example, translucent ceramics or glass can be used. The light diffusing member 90 has a configuration in which a light diffusing layer in which fine irregularities and particles (fillers, etc.) having different refractive indexes are mixed on the surface, intermediate layer, or the like, or a configuration using a translucent material. It is good. Thereby, the light quantity of the excitation light emitted from the light diffusing member 90 is made uniform by the polarization action and diffusion action of light. Therefore, by appropriately changing the material and amount of the light diffusing member, the irradiation range and the light amount of the excitation light can be adjusted in the first light projecting unit. In addition, the irradiation range and light quantity of the light within a 1st light projection unit can be adjusted also by changing a lens and protective glass suitably other than a light-diffusion member.

  As shown in FIG. 2, the electronic endoscope 11 includes a CCD 100, an analog processing circuit 104 (AFE: Analog Front End), and an imaging control unit 106. The CCD 100 receives the light transmitted through the excitation light cut filter 32, the observation window 62, and the condenser lens 102 by the imaging surface 100a. The CCD 100 photoelectrically converts the light received by the imaging surface 100a to accumulate signal charges, and reads the accumulated signal charges as imaging signals. The read imaging signal is sent to the AFE 104.

  The CCD 100 is a color CCD, and three pixels of R, G, and B pixels provided with R, G, and B color filters are arranged on the imaging surface 100a. Here, since the wavelength range of white light extends from the blue band to the red band, when white light is incident on the CCD imaging surface, all of the R pixel, G pixel, and B pixel are sensitive. Accordingly, the image pickup signal obtained when receiving white light includes three types of image pickup signal output from the R pixel, image pickup signal output from the G pixel, and image pickup signal output from the B pixel.

  On the other hand, autofluorescence has a main wavelength region in the green band, and a part extends to the blue band or the red band. For this reason, when the autofluorescence enters the imaging surface 100a of the CCD, the G pixel is surely sensitive to autofluorescence. Therefore, the imaging signal obtained at the time of receiving autofluorescence includes the imaging signal output from the G pixel.

  The AFE 104 includes a correlated double sampling circuit (CDS) and an automatic gain control circuit (AGC). The CDS performs correlated double sampling processing on the image pickup signal from the CCD to remove noise generated by driving the CCD 100. The AGC amplifies the imaging signal from which noise has been removed by CDS.

  The imaging control unit 106 performs imaging control of the CCD 44. In accordance with the imaging control of the imaging control unit 106, an imaging signal is output from the AFE 45 at a predetermined frame rate. The imaging control unit 106 is connected to the controller 113 in the processor device 15, and the imaging control unit 106 changes the control method as appropriate depending on the observation mode recognized by the controller 113 at the time of imaging.

  Here, as shown in FIG. 10A, when the normal light observation mode is set, a step of photoelectrically converting white light and accumulating signal charges is performed during the white light irradiation period. When the white light irradiation period is switched to the white light shielding period, an imaging signal readout pulse is transmitted from the imaging control unit 106 to the CCD 100. When the CCD 100 receives the imaging signal readout pulse, the signal charge accumulated in the CCD 100 is output to the AFE 104 as an imaging signal. Then, when the white light shielding period is switched to the white light irradiation period, a step of photoelectrically converting the white light and accumulating signal charges is performed again. The series of operations described above are repeated while the normal light image mode is set.

  On the other hand, when the autofluorescence observation mode is set, as shown in FIG. 10B, during the white light irradiation period, a step of photoelectrically converting white light and accumulating signal charges is performed. When the white light irradiation period is switched to the white light shielding period, an imaging signal readout pulse is transmitted from the imaging control unit 106 to the CCD 100. When the CCD 100 receives the imaging signal readout pulse, the signal charge accumulated in the CCD 100 is output to the AFE 104 as an imaging signal. Almost simultaneously with this, a step of photoelectrically converting autofluorescence to accumulate signal charges is performed. Although the autofluorescence is weak, it is possible to form an autofluorescence image by making the autofluorescence observation mode twice that of the autofluorescence observation mode, that is, the autofluorescence observation period in the normal light observation mode. Can be reliably received by the CCD 100.

  Then, after a lapse of a fixed time after switching from the white light irradiation period to the white light shielding period, an imaging signal readout pulse is transmitted from the imaging control unit 106 to the CCD 100. In response to this, the signal charge accumulated in the CCD 100 is output to the AFE 104 as an imaging signal. Then, when the white light shielding period is switched to the white light irradiation period, a step of photoelectrically converting the white light and accumulating signal charges is performed again. The above series of operations is repeated while the autofluorescence observation mode is set.

  As shown in FIG. 2, the processor device 15 is electrically connected to the electronic endoscope 11, the white light source device 16, the excitation light source device 17, the monitor 18, a keyboard (not shown), a printer (not shown), and the like. To control the overall operation of the electronic endoscope system 10 in an integrated manner. The processor device 15 includes a signal processing unit 110, a frame memory 112, and a controller 113.

  The signal processing unit 110 performs various processes on the imaging signal output from the AFE 104 of the electronic endoscope 11 by the A / D conversion unit 115, the color tone correction unit 116, and the image processing unit 117, thereby the monitor 18. A video signal that can be displayed is generated. Various images are displayed on the monitor 18 based on the video signal. Note that the color tone correction unit 116 and the image processing unit 117 are configured by, for example, software that performs corresponding processing and a storage device such as an EPROM (rewritable ROM) that stores the software. The digital image data after A / D conversion and the video signal after image processing in the image processing unit are stored in the frame memory 112 temporarily or each time processing is performed.

  The A / D conversion unit 115 converts the imaging signal from the AFE 104 into digital image data. The image data includes a B image obtained from the imaging signal output from the B pixel of the CCD 100, a G image obtained from the imaging signal output from the G pixel, and an R image obtained from the imaging signal output from the R pixel. It is. In addition, the image data after A / D conversion includes image data of a white light image acquired in the normal light observation mode or the autofluorescence observation mode, and image data of an autofluorescence image acquired in the autofluorescence observation mode. .

  The color tone correction unit 116 and the image processing unit 117 perform processing according to the flow shown in FIG. The color tone correction unit 116 supplements the component of the B image that is cut or reduced by the excitation light cut filter 32 in the white light image. As shown in FIG. 3, the electronic endoscope 11 performs imaging through an excitation light cut filter 32 that cuts or attenuates a component of a wavelength band of 415 nm or less, and therefore, among the white light image and the B image of the autofluorescence image Part of the low wavelength side is cut. Therefore, the color correction unit 116 corrects the cut image.

The correction of the B image of the white light image is performed as follows. First, the following correction equations (1) and (2) are obtained before using the endoscope. Here, when the excitation light cut filter is not attached, the B light amount of the white light image is B ′, and when the excitation light cut filter is attached, the B ′ image light amount of the white light image is B. , B and B ′ are expressed by the following equation (1).
B = B ′ × α (1)
Here, α is a light amount cut rate by the excitation light cut filter. Therefore, B ′ can be obtained by the following equation (2).
B ′ = B / α (2)

  As shown in Expression (2), when the relationship between B and B ′ is a linear relationship, the light quantity B of the B image of the white light image obtained when the excitation light cut filter is attached is expressed by a coefficient α. By dividing, the light amount B ′ of the portion cut by the excitation light cut filter is obtained. Then, by replacing the light amount B of the cut portion of the white light B image with the light amount B ′, a white light image similar to the case where the excitation light cut filter is not attached can be obtained.

  When the relationship between B and B ′ is not a linear relationship, the amount of light corresponding to the cut portion of the B image can be increased by, for example, arithmetic processing such as multiplication, addition, and matrix conversion. . Further, the components of the G image and the R image may be reduced by the component corresponding to the cut component of the B image. Furthermore, when some components on the low frequency side of the G image are cut by the excitation light cut filter, it is preferable to perform color tone correction in the same manner as in the case of the B image.

  The image processing unit 117 illustrated in FIG. 2 performs balance adjustment processing, high sensitivity processing, and display gradation processing on the image data that has been subjected to color tone correction. The balance adjustment process is a process for adjusting the balance between the white light image and the autofluorescence image using the calibration data when the autofluorescence observation mode is set. The calibration data is obtained from a white light image and an autofluorescence image captured in advance for a lesion part (an occurrence part of early cancer, etc.) and a normal part of an unspecified subject.

  By performing balance adjustment using the calibration data, for example, the contrast between the lesioned part and the normal part in the white light image is equal to the contrast between the lesioned part and the normal part in the autofluorescence image. For example, when the contrast of the autofluorescence image is 1/5 with respect to the contrast of the white light image, the color tone correction unit 116 adjusts the balance to make the contrast of the autofluorescence image 5 times based on the calibration data. To do. As described above, the balance adjustment is performed with higher accuracy because the light quantity ratio between the white light and the excitation light is kept constant.

  Since the balance between the white light image and the autofluorescence image depends on the characteristics of the CCD or the like, the balance adjustment should be performed at least before shipping the electronic endoscope system to the factory or before using the electronic endoscope system for the first time. It is preferable to carry out once.

  High sensitivity processing includes processing such as digital gain, frame addition, and digital binning. By performing this sensitivity enhancement process, the sensitivity of the autofluorescence image can be enhanced. Digital gain is a process of amplifying digital image data with a predetermined amplification factor. Frame addition is a process for obtaining image data for one frame by adding image data of a plurality of consecutive frames. Digital binning is a process for increasing the sensitivity of a CCD by increasing the light receiving area by setting a plurality of adjacent images in the CCD as one set and outputting an imaging signal in units of the set. The sensitivity enhancement process may be performed not only on the autofluorescence image but also on the white light image.

  The display gradation processing is processing for converting a white light image or an autofluorescence image into a video signal that can be displayed on a monitor. This display gradation processing includes γ correction processing and gradation correction processing corresponding to the monitor. In this display gradation processing, when the normal light observation mode is set, among the white light images, the B image is the B channel signal of the video signal, the G image is the G channel signal of the video signal, R An image is assigned to the R channel signal.

  On the other hand, when the auto-fluorescence observation mode is set, the B image of the white light image is assigned to the B channel signal of the video signal, and the R image of the white light image is assigned to the R channel signal of the video signal. The G image is assigned to the G channel signal of the video signal. Thereby, a composite image in which the white light image and the autofluorescence image are combined is obtained. By displaying such a composite image on the monitor 18, the normal part is displayed in green and the lesioned part is displayed in magenta.

  Note that the brightness level of the autofluorescence is lowered due to the fact that the imaging distance is increased in addition to the lesion. Therefore, the image processing unit compares the brightness levels of the G image of the white light image and the G image of the autofluorescence image before displaying the magenta color on the monitor. If both are low as a result of the comparison, it is determined that the brightness level is low because the imaging distance is far and not the lesion, and the display is displayed in green instead of magenta. On the other hand, when the brightness level of the G image of the white light image is high and the brightness level of the autofluorescence image is low, the white light image is determined to be a lesion and displayed in magenta.

  Next, the operation of the present invention will be described. First, the auto fluorescence observation mode is set by the observation mode switching button 28. In the auto-fluorescence observation mode, in addition to the white light source device 16 being always turned on, the excitation light source device 17 is also always turned on. In the light source device 16 for white light, white light is incident on the first and second light guides 55 and 56 during the white light irradiation period, while white light is incident on the first and second light guides 55 and 56 during the white light blocking period. 56 does not enter. On the other hand, in the excitation light source device 17, the excitation light from the first laser light source 72 is always incident on the first optical fiber 38 and the excitation light from the second laser light source 73 is always incident on the second optical fiber 39. To do.

  White light in the first light guide 55 is emitted from the first illumination window 57 of the distal end portion 24a toward the body cavity, and white light in the second light guide 56 is emitted from the second illumination window 59 of the distal end portion 24a into the body cavity. It is emitted toward When the distal end portion 24a is directed to the observation target T from the arrangement positions of the first and second illumination windows 57 and 59 in the distal end portion 24a and the white light irradiation ranges WL1, WL2, and WLR, the observation target T has white light. Is sufficiently and evenly illuminated.

  On the other hand, the excitation light in the first optical fiber 38 is emitted from the first light projecting unit 41 fixed to the hood 14 toward the body cavity, and the excitation light in the second optical fiber 39 is fixed to the hood 14. 2 The light is emitted from the light projecting unit 42 into the body cavity. When the distal end portion 24a is directed to the observation target T from the arrangement positions of the first and second light projecting units 41 and 42 and the irradiation ranges EL1, EL2, and ELR of the excitation light, the observation target T has sufficient excitation light. Moreover, it is irradiated without illumination unevenness. Thereby, for example, when the entire observation target T is a normal part, substantially the same autofluorescence is emitted from the entire area of the observation target T. In addition, since the overlap area ELR of the two excitation light irradiation ranges is included in the overlap area WLR of the two white light irradiation ranges, the light quantity ratio of the white light and the excitation light in the entire observation target T is Held constant.

  The electronic endoscope 11 uses a color CCD 100 including B pixels, G pixels, and R pixels to capture a white light image when in the white light irradiation period and an autofluorescence image when in the white light shading period. To do. The imaging signals acquired by these imaging are sent to the processor device 15.

  In the processor device 15, the A / D conversion unit 115 converts the imaging signal into digital image data. Thereby, the image data including the B image obtained from the imaging signal output from the B pixel of the CCD 100, the G image obtained from the imaging signal output from the G pixel, and the R image obtained from the imaging signal output from the R pixel. Is obtained.

  Then, based on the obtained image data, the tone correction unit 116 corrects the B image. Thereafter, the image processing unit 117 performs balance adjustment using the calibration data, high sensitivity processing, and display gradation processing. Through these processes, a composite image obtained by combining the white light image and the autofluorescence image is obtained. Then, this composite image is displayed on the monitor 18.

  In the autofluorescence observation mode, the white light amount control is performed by the white light control unit 47 and the excitation light amount control is performed by the excitation light control unit 75. For example, the white light control unit 47 calculates the average value of the luminance of the G image of the white light image, and controls the amount of white light so that the average value becomes a predetermined luminance set in advance. Further, the excitation light control unit 75 controls the light amount of the excitation light according to the light amount control of the white light in the white light control unit 47 so that, for example, the light amount ratio between the excitation light and the white light is maintained at 1/10 or the like. .

  As shown in FIGS. 12 and 13, the electronic endoscope system 200 according to the second embodiment of the present invention is a light projecting unit that irradiates excitation light, and the first and second light projections shown in the first embodiment. In addition to the light units 41 and 42, third and fourth light projecting units 202 and 203 are provided in the hood 14, and excitation is performed from two of the four first to fourth light projecting units 41, 42, 202, and 203. Light is irradiated into the body cavity. Since the rest is the same as in the first embodiment, the description thereof is omitted below. In the second embodiment, excitation light irradiation is performed by two light projecting units. However, the present invention is not limited to this, and may be performed by three or four light projecting units.

  The third light projecting unit 202 is provided in the vicinity of the first light projecting unit 41, and the fourth light projecting unit 203 is provided in the vicinity of the second light projecting unit 42. Further, the light diffusing member, the lens, and the protective glass used in the third and fourth light projecting units 202 and 203 are different from those used in the first and second light projecting units 41 and 42. Therefore, the irradiation range of the excitation light irradiated from the third light projection unit 202 is different from the irradiation range of the first light projection unit 41 in the vicinity thereof, and the irradiation range of the excitation light irradiated from the fourth light projection unit 203. Is different from the irradiation range of the second light projecting unit 42 in the vicinity thereof. By utilizing the difference in irradiation range in the first to fourth light projecting units 41, 42, 202, and 203, the irradiation pattern can be changed flexibly according to the observation situation.

  The switching mirrors 207 and 208 in the excitation light source device 206 are configured so that the excitation light is emitted from desired light projection units 41, 42, 202, and 203 among the first to fourth light projection units. The optical path of the excitation light is switched in the light source device. The switching mirror 207 reflects the excitation light from the first laser light source 72 and the retracted position where the excitation light from the first laser light source 72 is incident on the first optical fiber 38 as it is, and the reflected light is third projected. It is movable between an insertion position for entering the third optical fiber 210 connected to the unit 202. The other switching mirror 208 reflects the excitation light from the second laser light source 73 and the retracted position where the excitation light from the second laser light source 73 is directly incident on the second optical fiber 39, and reflects the reflected light to the first optical fiber 39. It is movable between the insertion position for incidence on the fourth optical fiber 211 connected to the four light projecting unit 203.

  In the first and second embodiments, the body cavity is irradiated with white light as it is, but instead of this, surface sequential light consisting of R color light, G color light, and B color light is emitted into the body cavity. May be irradiated. In order to irradiate the surface sequential light, a rotary filter 220 as shown in FIG. 14 is used instead of the rotary shutter 48 shown in FIGS. 6A and 6B. The rotary filter 220 includes a light shielding unit 221 similar to the light shielding unit 48 b of the rotary shutter 48, an R color filter 223 r that transmits R light among white light from the white light source 45, and the white light source 45. A G color filter 223g that transmits G light in the white light and a B color filter 223b that transmits B light in the white light from the white light source 45 are provided along the circumferential direction. It has been. By rotating the rotary filter 220 around the rotation shaft 220a, R light, G light, and B light are irradiated in this order in the body cavity during the white light irradiation period.

  In the first and second embodiments, the white light emitted into the body cavity is generated by the white light source in the white light source device. Instead, the electronic endoscope system in FIG. As shown at 300, white light may be generated by the blue laser light source 304 in the white light source device and the light projecting units 306 and 307 provided in the distal end portion 24a of the electronic endoscope. The blue laser light source 304 emits blue laser light having a center wavelength of 445 nm. The emitted blue laser light is emitted from the light projecting units 306 and 307 toward the inside of the body cavity via the light guides 55 and 56. The blue laser light source 304 is controlled by the blue laser light control unit 305 through the driver 305a.

As shown in FIG. 16, the light projecting unit 306 has the same configuration as the first and second light projecting units 41 and 42 except that a phosphor 310 is provided instead of the light diffusing member. The phosphor 310 absorbs a part of the blue laser light from the light guide 55 and emits green to yellow excitation light (for example, YAG phosphor, BAM (BaMgAl ₁₀ O ₁₇ ), etc.). Phosphor). As a result, green to yellow excitation light that uses blue laser light as excitation light and blue laser light that is transmitted without being absorbed by the phosphor 310 are combined to generate white light. The light projecting unit 307 is also the same as the light projecting unit 306, and a description thereof will be omitted.

  In the first and second embodiments, the case where the AFI for observing the autofluorescence emitted from the endogenous fluorescent substance in the living tissue by irradiation with the excitation light has been applied to the present invention. The present invention can also be applied to PDD (Photo Dynamic Diagnosis) in which fluorescence observation is performed using a fluorescent agent.

10, 200, 300 Electronic endoscope system 11 Electronic endoscope 13 Overtube 14 Hood 16, 302 White light source device 17, 206 Excitation light source device 20 Insertion portion 24a Tip portion 32 Excitation light cut filters 38, 39 First and second optical fibers 41 and 42 First and second light projecting units 202 and 203 Third and fourth light projecting units 210 and 211 Third and fourth optical fibers

Claims (12)

A light source device for excitation light that emits excitation light for exciting fluorescence from living tissue in the body cavity;
An electronic endoscope having an insertion portion to be inserted into a body cavity;
An overtube through which the insertion part of the electronic endoscope is inserted;
An excitation light guide member that is provided in an overtube and guides excitation light emitted from the excitation light source device;
An electronic endoscope system comprising a light projecting unit that irradiates the excitation light guided by the excitation light guide member toward a body cavity. The electronic endoscope is:
An observation window provided at the distal end of the insertion portion and receiving the light reflected in the body cavity;
A hood for attaching a tip having an excitation light cut filter that cuts light including the wavelength band of excitation light among light before entering the observation window;
The electronic endoscope system according to claim 1, wherein the light projecting unit is fixed to an outer peripheral surface of the hood.   3. The electronic endoscope system according to claim 2, wherein the light projecting unit includes two first and second light projecting units provided at symmetrical positions with respect to the observation window.   The light projecting unit is provided in the vicinity of the first light projecting unit, and a third light projecting unit in which an excitation light irradiation range is different from an excitation light irradiation range in the first light projecting unit, and the second light projecting unit. The electronic endoscope system according to claim 3, further comprising a fourth light projecting unit provided in the vicinity of the unit and having an excitation light irradiation range different from the excitation light irradiation range in the second light projection unit. .   5. The irradiation range of excitation light in each light projecting unit is made different by incorporating different light diffusion members, lenses, and protective glasses in each light projecting unit. Electronic endoscope system.   A switching unit that switches an optical path of the excitation light in the light source device of the excitation light is provided so that excitation light is emitted from a predetermined light projection unit among the first to fourth light projection units. Item 5. The electronic endoscope system according to Item 4. The electronic endoscope is:
Provided at the distal end of the insertion portion, and having an irradiation window for irradiating white light with a wavelength ranging from a blue band to a red band into the body cavity
The electronic endoscope system according to claim 1, wherein the excitation light irradiation range is within the white light irradiation range.   The electronic endoscope system according to claim 7, wherein a light amount ratio between the excitation light and the white light is kept constant.   9. The electronic endoscope system according to claim 7, wherein the white light is a surface sequential light that is irradiated in a time-division manner with light of R color, light of G color, and light of B color.   The electronic endoscope system according to any one of claims 7 to 9, wherein the white light is light that is excited and emitted from the phosphor when the phosphor is irradiated with blue light having a specific wavelength. In an electronic endoscope connected to a light source device of excitation light that emits excitation light for exciting fluorescence from biological tissue in a body cavity,
An insertion part to be inserted into the body cavity;
An overtube through which the insertion portion is inserted;
An excitation light guide member that is provided in an overtube and guides excitation light emitted from the excitation light source device;
An electronic endoscope comprising a light projecting unit that irradiates the excitation light guided by the excitation light guide member toward a body cavity. In an excitation light irradiation method using an excitation light source device that emits excitation light for exciting fluorescence from a living tissue in a body cavity, and an electronic endoscope in which an insertion portion inserted into the body cavity is inserted through an overtube ,
Excitation light emitted from the excitation light source device is guided by an excitation light guide member provided on an overtube, and the guided excitation light is irradiated from the light projecting unit into the body cavity. Excitation light irradiation method.

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