JP5774531B2 - ENDOSCOPE SYSTEM, ENDOSCOPE SYSTEM PROCESSOR DEVICE, ENDOSCOPE SYSTEM OPERATING METHOD, AND IMAGE PROCESSING PROGRAM - Google Patents

Description

The present invention relates to an endoscope system that displays an oxygen saturation image obtained by imaging oxygen saturation of blood hemoglobin as a moving image, a processor device of the endoscope system, an operation method of the endoscope system , and an image processing program. It is.

  In the medical field, endoscopic diagnosis using an electronic endoscope has become widespread. In recent endoscopic diagnosis, special light observation using special light limited to a specific wavelength is performed in addition to normal observation of observing the overall properties of the surface of living tissue under white light. It has come to be.

  There are various types of special light observations. For example, in the endoscope system of Patent Document 1, by using narrowband light in a wavelength range in which there is a difference in the absorption coefficient of oxyhemoglobin and reduced hemoglobin, Based on a spectral image obtained by imaging the reflected light, the oxygen saturation of blood hemoglobin is calculated and imaged. Here, since oxygen saturation is greatly influenced also by the depth of the blood vessel, in Patent Document 1, by using a luminance ratio between predetermined spectral images, noise caused by the depth of the blood vessel is removed, The calculation accuracy of oxygen saturation is improved.

  In the endoscope system of Patent Document 1, as a method for acquiring a plurality of spectral images, a sequential method of sequentially irradiating and imaging a biological tissue with a plurality of narrowband lights is employed. A positional shift between a plurality of spectral images caused by a time difference becomes a problem. With respect to this problem of positional deviation, in Patent Document 1, the position of a blood vessel is aligned between spectral images by pattern matching. In Patent Document 1, frequency filtering processing according to the blood vessel depth is performed in order to increase the accuracy of pattern matching.

JP 2011-194151 A

  As described in Patent Document 1, development of a highly accurate alignment technique is being promoted in order to image accurate oxygen saturation. In the process, as shown below, there is room for technological improvement. There is.

  Since the oxygen saturation image is observed during the examination, it is premised on a moving image display. In the moving image display of the oxygen saturation image, if even a slight misalignment occurs between a plurality of spectral images, the image flickers and the visibility is lowered, which is a cause of lowering the diagnostic ability. On the other hand, accurate alignment processing of a plurality of spectral images (alignment processing that matches not only the central portion of the image but also the peripheral portion) is large because the load on the hardware configuration of the processor device is large. Expensive processing equipment was required.

The present invention has been made in view of the above problems, and reduces the load on the hardware configuration of the processor device that accompanies the alignment processing, and displays an oxygen saturation image in a moving image without flickering, and an endoscope system It is an object of the present invention to provide a processor device, an endoscope system operating method, and an image processing program.

  The endoscope system according to the present invention includes an image acquisition unit that acquires a first image having a broadband component, a correspondence relationship storage unit that previously stores a correspondence relationship between the oxygen saturation of blood hemoglobin and the first image, Oxygen saturation calculation means for obtaining oxygen saturation corresponding to the first image acquired by the image acquisition means from correspondence relationship storage means; and oxygen saturation obtained by imaging the oxygen saturation calculated by the oxygen saturation calculation means And moving image display means for displaying an image as a moving image.

  In addition to the first image, the image acquisition means acquires a second image having wavelength components having different absorption coefficients of oxyhemoglobin and reduced hemoglobin, and the oxygen saturation calculation means includes the first image and the second image. Based on the image, a temporary oxygen saturation calculation unit that calculates provisional temporary oxygen saturation, an association unit that associates the temporary oxygen saturation with the first image, the temporary oxygen saturation and the first image, And the oxygen saturation corresponding to the first image acquired by the image acquisition unit, and the update unit that updates the correspondence stored in the correspondence storage unit It is preferable to have an oxygen saturation calculation unit that is obtained from the correspondence storage means.

  It is preferable that the temporary oxygen saturation calculating unit obtains the temporary oxygen saturation after aligning only the central portion between the first and second images. When the correspondence between the temporary oxygen saturation and the first image does not match the correspondence in the correspondence storage unit, the update unit performs an averaging process based on the correspondence and then performs the correspondence It is preferable to update the relationship storage means.

Preferably, the first image includes a plurality of spectral images having different wavelength components, and the correspondence storage means stores a correspondence between a luminance ratio between predetermined spectral images and the oxygen saturation. The plurality of spectral images are a blue spectral image, a green spectral image, and a red spectral image, and the correspondence storage means includes a first signal ratio between the blue spectral image and the green spectral image, and a red spectral image. It is preferable to store a correspondence relationship between the second signal ratio between the spectral image and the green spectral image and the oxygen saturation.

  Illuminating means for irradiating the subject with white light, and the image acquisition means captures the reflected image of the white light with a color image sensor, thereby the blue spectral image, the green spectral image, and the It is preferable to acquire a red spectral image. The white light preferably includes blue narrow band light and fluorescence obtained by wavelength conversion of the blue narrow band light with a wavelength conversion member. Illuminating means for sequentially irradiating the subject with blue light, green light, and red light, and the image acquisition means sequentially captures reflected images of light of each color with a monochrome image sensor, thereby the blue spectral image, It is preferable to acquire the green spectral image and the red spectral image.

  The present invention prestores a correspondence relationship between oxygen saturation of blood hemoglobin and a first image in a processor device of an endoscope system connected to an electronic endoscope that acquires a first image having a broadband component. Correspondence storage means; oxygen saturation calculation means for obtaining oxygen saturation corresponding to the first image acquired by the electronic endoscope from the correspondence storage means; and oxygen saturation obtained by the oxygen saturation calculation means And a display control means for displaying a moving image of the oxygen saturation image obtained by imaging the degree on the display means.

Operation method of the endoscope system of the present invention, the image acquisition means, the steps that get the first image having a wide band component, the oxygen saturation calculating unit, the oxygen saturation and the first image of the blood hemoglobin A step of obtaining an oxygen saturation corresponding to the first image acquired by the image acquisition means from a correspondence storage means for storing the correspondence relation in advance; and an oxygen saturation obtained by the moving image display means by the oxygen saturation calculation means. And a step of displaying an oxygen saturation image obtained by imaging a moving image.

  According to the present invention, in an image processing program for processing an image acquired by an image acquisition unit of an electronic endoscope, a computer stores in advance a correspondence relationship between a first image having a broadband component and oxygen saturation of blood hemoglobin. Oxygen saturation calculating means for obtaining oxygen saturation corresponding to the first image obtained by the image obtaining means from the correspondence storage means, and oxygen saturation obtained by imaging the oxygen saturation obtained by the oxygen saturation calculating means. The image is caused to function as display control means for displaying a moving image on the display means.

  According to the present invention, the oxygen corresponding to the first image acquired by the image acquisition unit such as an electronic endoscope from the correspondence storage unit that stores in advance the correspondence between the oxygen saturation of blood hemoglobin and the first image. The saturation is obtained, and an oxygen saturation image obtained by imaging the obtained oxygen saturation is displayed as a moving image. Therefore, in the present invention, since the alignment process is simply performed, the load on the hardware configuration of the processor device associated with the alignment process is reduced, and a moving image is displayed based on the first image of one frame. Therefore, flicker does not occur in the video.

It is an external view of the endoscope system of the present invention. It is a block diagram which shows the electric constitution of an endoscope system. It is a graph which shows the spectrum of illumination light. It is a graph which shows the spectral characteristic of the color microfilter of an image pick-up element. It is explanatory drawing which shows the irradiation timing and imaging timing of illumination light in normal observation mode. It is explanatory drawing which shows the irradiation timing and imaging timing of illumination light in functional information observation mode. It is a block diagram of a functional image processing part in a 1st embodiment. It is explanatory drawing of simple alignment. It is explanatory drawing which shows a response | compatibility with the absorption spectrum of hemoglobin, and the wavelength of illumination light. It is a graph which shows correlation with luminance ratio S1 / S3, S2 / S3, blood vessel depth, and oxygen saturation. It is explanatory drawing for demonstrating the method of calculating | requiring the coordinate (X *, Y *) in a luminance coordinate system from luminance ratio S1 * / S3 *, S2 * / S3 *. It is explanatory drawing for demonstrating the method of calculating | requiring the coordinate (U *, V *) of the blood-vessel information coordinate system corresponding to coordinate (X *, Y *). It is explanatory drawing explaining matching of white signal ratio data and temporary oxygen saturation data. It is a table | surface which shows the table for temporary oxygen saturation. It is explanatory drawing for demonstrating the update method of a 2nd memory | storage table. It is explanatory drawing for demonstrating an averaging process. It is a table | surface which shows the updated 2nd memory | storage table. It is a graph which shows the relationship between a gain value and oxygen saturation. It is an image figure which shows an oxygen saturation image. It is a flowchart which shows the effect | action of this invention. It is an external view of the endoscope system in 2nd Embodiment. It is explanatory drawing which shows the irradiation timing and imaging timing of illumination light in the function information observation mode of 2nd Embodiment. It is a block diagram of the functional image processing part in 2nd Embodiment. It is a graph which shows the correlation with oxygen saturation and signal ratio B2 / G1, R1 / G1. It is explanatory drawing explaining the method of calculating | requiring oxygen saturation from a signal ratio in the graph of FIG. It is the schematic which shows the light source device which carries out wavelength separation from the broadband of white light sources, such as a xenon lamp, and produces | generates light. It is a figure which shows a rotation filter. It is explanatory drawing for demonstrating the irradiation timing and imaging timing in normal observation mode of another embodiment. It is explanatory drawing for demonstrating the irradiation timing and imaging timing in the functional information observation mode of another embodiment.

[First Embodiment]
As shown in FIG. 1, an endoscope system 10 according to a first embodiment of the present invention includes an electronic endoscope 11 that images an observation site in a subject, and an observation site based on a signal obtained by imaging. A processor device 12 that generates an observation image, a light source device 13 that supplies light for irradiating the observation site, and a monitor 14 that displays the observation image are provided. The processor device 12 is provided with a console 15 that is an operation input unit such as a keyboard and a mouse.

  The endoscope system 10 has two operation modes: a normal observation mode in which an observation site is observed under white light, and a function information observation mode. The function information observation mode is a mode in which information on the oxygen saturation level of blood hemoglobin is acquired, and these are imaged and observed. These observation modes are appropriately switched based on input information input by the changeover switch 16 or the console 15 of the electronic endoscope 11.

  The electronic endoscope 11 includes a flexible insertion portion 17 to be inserted into a subject, an operation portion 18 provided at a proximal end portion of the insertion portion 17, an operation portion 18, a processor device 12, and a light source device. 13 is provided with a universal cord 19 that connects the two.

  The insertion portion 17 includes a distal end portion 20, a bending portion 21, and a flexible tube portion 22 that are continuously provided from the distal end. In addition to the illumination window 23 that irradiates the observation site with illumination light and the observation window 24 that receives the image light reflected by the observation site (see FIG. 2), the distal end surface of the distal end portion 20 is used to clean the observation window 24. An air supply / water supply nozzle for supplying air and water, a forceps outlet for projecting a treatment tool such as a forceps and an electric knife, and the like are provided (not shown). An imaging element 44 (see FIG. 2) and an imaging optical system are built in the back of the observation window 24.

  The bending portion 21 is composed of a plurality of connected bending pieces, and is bent in the vertical and horizontal directions by operating the angle knob 26 of the operation portion 18. As the bending portion 21 is bent, the tip portion 20 is oriented in a desired direction. The flexible tube portion 22 is flexible so that it can be inserted into a tortuous duct such as the esophagus or the intestine. The insertion unit 17 includes a communication cable that communicates a drive signal for driving the image sensor 44 and an image signal output from the image sensor 44, and a light guide 43 that guides illumination light supplied from the light source device 13 to the illumination window 23. (See FIG. 2) is inserted.

  In addition to the amble knob 26, the operation unit 18 is provided with a forceps port for inserting a treatment instrument, an air / water supply button for performing air / water supply operation, a release button for capturing a still image, and the like.

  A communication cable and a light guide 43 extending from the insertion portion 17 are inserted into the universal cord 19. A connector 27 is attached to one end of the universal cord 19 on the processor device 12 and the light source device 13 side. The connector 27 is a composite type connector composed of a communication connector and a light source connector, and one end of a communication cable is disposed on the communication connector, and one end of the light guide 43 is disposed on the light source connector. The electronic endoscope 11 is detachably connected to the processor device 12 and the light source device 13 through the connector 27.

  As shown in FIG. 2, the light source device 13 includes a semiconductor light source unit 31 and a light source control unit 32 that drives and controls them. The light source control unit 32 controls drive timing and synchronization timing of each unit of the light source device 13.

  The semiconductor light source unit 31 includes three laser light sources LD1 to LD3 that respectively emit narrowband light limited to a specific wavelength region in the blue region, and a phosphor 37. As shown in FIG. 3, the laser light source LD1 emits narrowband light N1 whose wavelength range is limited to 440 ± 10 nm, preferably 445 nm. The emitted narrow-band light N1 is incident on a phosphor 37 provided between the laser light source LD1 and the optical fiber 34. In the phosphor 37, a part of the narrow band light N1 is absorbed and the fluorescence FL is excited and emitted, and the rest is transmitted without being absorbed. As a result, white light W obtained by combining the fluorescent light FL and the narrow-band light N1 that has not been absorbed by the phosphor 37 is emitted from the phosphor 37.

As the phosphor 37, for example, a YAG-based or BAM (BgMgAl ₁₀ O ₁₇ ) -based phosphor is used, and preferably has a substantially rectangular parallelepiped shape. In this case, the phosphor 37 may be formed by fixing the phosphor material in a substantially rectangular parallelepiped shape with a binder, or may be formed by mixing a phosphor material in a resin such as inorganic glass in a substantially rectangular parallelepiped shape. . The phosphor 37 is also called “Micro White (MW)” as a trade name.

  The laser light source LD2 emits narrow band light N2 whose wavelength range is limited to 470 ± 10 nm, preferably 473 nm. The laser light source LD3 emits narrow band light N3 whose wavelength range is limited to 400 ± 10 nm, preferably 405 nm. As the laser light sources LD1 to LD3, InGaN-based, InGaNAs-based, and GaNAs-based laser diodes can be used. Further, as the laser light sources LD1 to LD3, a broad area type laser diode having a wide stripe width (waveguide width) capable of increasing output is preferable.

  The light source controller 32 controls turning on / off of the laser light sources LD <b> 1 to LD <b> 3 and the amount of light through the driver 33. White light W emitted from the phosphor 37 when the laser light source LD1 is turned on is guided to the combiner 36 by the optical fiber 34. On the other hand, the light emitted from the laser light sources LD <b> 2 to LD <b> 3 is guided to the combiner 36 by the optical fiber 34. The combiner 36 is an optical member having a function of multiplexing the light from each optical fiber 34 and couples the optical axes of the light from each optical fiber 34 that selectively enters into one.

  In FIG. 2, a condenser lens 38 and a rod integrator 39 are arranged on the downstream side of the combiner 36. The condensing lens 38 condenses the light from the combiner 36 and makes it incident on the rod integrator 39. The rod integrator 39 makes the in-plane light quantity distribution uniform by internally reflecting the incident light, and makes the light enter the incident end of the light guide 43 of the electronic endoscope 11 connected to the light source device 13.

  The electronic endoscope 11 includes a light guide 43, an imaging device 44, an analog processing circuit 45 (AFE: Analog Front End), and an imaging control unit 46. The light guide 43 is a large-diameter optical fiber, a bundle fiber, or the like. When the connector 27 on which the incident end of the light guide 43 is disposed is connected to the light source device 13, the incident end is emitted from the rod integrator 39 of the light source device 13. Opposite the edge.

  An illumination lens 48 that adjusts the light distribution angle of the illumination light is disposed behind the illumination window 23. The light supplied from the light source device 13 is guided to the irradiation lens 48 by the light guide 43 and irradiated from the illumination window 23 toward the observation site. In the back of the observation window 24, an objective optical system 51 and an image sensor 44 are arranged. The image light reflected by the observation site enters the objective optical system 51 through the observation window 24 and is imaged on the imaging surface 44 a of the imaging element 44 by the objective optical system 51.

  The imaging element 44 is composed of a CCD image sensor, a CMOS image sensor, or the like, and has an imaging surface 44a in which a plurality of photoelectric conversion elements constituting pixels such as photodiodes are arranged in a matrix. The image sensor 44 photoelectrically converts the light received by the imaging surface 44a and accumulates signal charges corresponding to the amount of received light in each pixel. The signal charge is converted into a voltage signal by an amplifier and read out. The voltage signal is output as an imaging signal from the imaging device 44, and the imaging signal is sent to the AFE 45.

  The image pickup device 44 is a color image pickup device, and on the image pickup surface 44a, B, G, and R three-color micro color filters having spectral characteristics as shown in FIG. 4 are assigned to each pixel. The B micro color filter has a transmission band of 380 to 560 nm, the G micro color filter has a transmission band of 450 to 630 nm, and the R micro color filter has a transmission band of 580 to 760 nm. The arrangement of the micro color filters is preferably a Bayer arrangement, for example.

  As shown in FIG. 5A, in the normal observation mode, the image sensor 44 performs an accumulation operation for accumulating signal charges and a read operation for reading the accumulated signal charges within an acquisition period of one frame. In the normal observation mode, the laser light source LD1 is turned on in accordance with the accumulation timing, the white light W is irradiated as the illumination light on the observation site, and the reflected light is incident on the image sensor 44. The imaging element 44 sequentially outputs the imaging signals B, G, and R for one frame in which the luminance values of the B, G, and R pixels are mixed according to the frame rate. Such an imaging operation is repeated while the normal observation mode is set.

  In the function information observation mode, as shown in FIG. 5B, the laser light sources LD1, LD2, and LD3 are sequentially turned on in accordance with the accumulation timing. When the laser light source LD1 is turned on, the observation site is irradiated with white light W as in the normal observation mode. When the laser light source LD2 is turned on, the observation region is irradiated with narrowband light N2 as illumination light. When the laser light source LD3 is turned on, the narrow-band light N3 is irradiated to the observation site as illumination light. In the functional information observation mode, as in the normal observation mode, the image sensor 44 sequentially outputs the image signals B, G, and R for one frame in which the luminance values of the B, G, and R pixels are mixed according to the frame rate. To do. Such an imaging operation is repeated while the function information observation mode is set.

  As shown in FIG. 2, the AFE 45 includes a correlated double sampling circuit (CDS), an automatic gain control circuit (AGC), and an analog / digital converter (A / D) (all not shown). The CDS performs correlated double sampling processing on the image signal from the image sensor 44 to remove noise caused by signal charge reset. The AGC amplifies the imaging signal from which noise has been removed by CDS. The A / D converts the imaging signal amplified by AGC into a digital imaging signal having a gradation value corresponding to a predetermined number of bits and inputs the digital imaging signal to the processor device 12.

  The imaging control unit 46 is connected to a controller 56 in the processor device 12 and inputs a drive signal to the imaging element 44 in synchronization with a base clock signal input from the controller 56. The imaging element 44 outputs an imaging signal to the AFE 45 at a predetermined frame rate based on the drive signal from the imaging control unit 46.

  In addition to the controller 56, the processor device 12 includes a DSP (Digital Signal Processor) 57, an image processing unit 58, a frame memory 59, and a display control circuit 60. The controller 56 includes a CPU, a ROM that stores a control program and setting data necessary for control, a RAM that loads the program and functions as a work memory, and the like. To control.

  The DSP 57 acquires an image signal output from the image sensor 44. The DSP 57 separates an imaging signal in which signals corresponding to B, G, and R pixels are mixed into imaging signals of three colors, performs pixel interpolation processing on the imaging signals of each color, and performs B, G, and R A spectral image of each color is generated. In addition, the DSP 57 performs signal processing such as gamma correction and white balance correction on the imaging signals of the B, G, and R spectral images.

  The frame memory 59 stores image data output by the DSP 57 and processed data processed by the image processing unit 58. The display control circuit 60 reads the image processed image data from the frame memory 59, converts it into a video signal such as a composite signal or a component signal, and outputs it to the monitor 14.

  The image processing unit 58 includes a normal image processing unit 61 and a functional image processing unit 62, and performs predetermined image processing on the image signal from the electronic endoscope 11. The normal image processing unit 61 generates a white image W composed of a blue spectral image PB1, a green spectral image PG1, and a red spectral image PR1 based on the image color-separated by the DSP 57 in the normal observation mode.

  In the function information observation mode, the functional image processing unit 62 performs blood hemoglobin based on the three white images W, the spectral image PB2, and the spectral image PB3 that are sequentially acquired in accordance with the irradiation timing of the white light W, N2, and N3. The oxygen saturation of is calculated. As shown in FIG. 6, the functional image processing unit 62 calculates temporary oxygen saturation based on the spectral image PB1, the spectral image PB2, and the spectral image PB3 in the white image W. Unit 63, oxygen saturation is calculated from the correspondence between the white image W and the oxygen saturation, and the correspondence is sequentially updated for each calculation of the temporary oxygen saturation, and the oxygen saturation is calculated. An image generation unit 69 for generating an imaged oxygen saturation image.

  The temporary oxygen saturation calculation unit 63 includes a simple alignment processing unit 63a, a luminance ratio calculation unit 63b, a first storage table 63c, and a first calculation unit 63d. The simple alignment processing unit 63a performs simple alignment (hereinafter referred to as “simple alignment processing”) between the spectral images PB1, PB2, and PB3. The simple alignment processing unit 63a reads the spectral images PB1, PB2, and PB3 from the frame memory 59. Then, as shown in FIG. 7, the spectral images PB1, PB2, and PB3 are translated and aligned so that the center positions C1, C2, and C3 of the spectral images coincide. Alternatively, a reference point may be provided in the central portion of the spectral images PB1, PB2, and PB3, and the reference points may be translated and aligned so that they coincide between the spectral images PB1, PB2, and PB3. In the case of such alignment of only the central portion, the load on the processor device 12 is greatly reduced.

  The luminance ratio calculation unit 63b reads the spectral images PB1, PB2, and PB3 that have undergone the simple alignment processing from the frame memory 59, obtains the luminance ratio S1 / S3 between the spectral image PB1 and the spectral image PB3, and the spectral image. The luminance ratio S2 / S3 between PB2 and the spectral image PB3 is obtained. Here, S1 represents the luminance value of the pixel of the spectral image PB1, S2 represents the luminance value of the pixel of the spectral image PB2, and S3 represents the luminance value of the pixel of the spectral image PB3. The luminance value S3 represents the brightness level of the observation region, and is a reference signal for normalizing the luminance values S1 and S2 in order to compare the luminance values S1 and S2. The luminance ratio S1 / S3 and the luminance ratio S2 / S3 are calculated for all corresponding pixels between the spectral images PB1, PB2, and PB3.

  The first storage table 63c stores the correlation between the brightness ratios S1 / S3, S2 / S3 and the oxygen saturation. The correlation of the first storage table 63c is mainly determined by the light absorption characteristic represented by the absorption spectrum of hemoglobin in the blood. The first storage table 63c also stores the correlation between the luminance ratios S1 / S3, S2 / S3 and the blood vessel depth.

  Here, as shown in FIG. 8, among hemoglobin in blood, reduced hemoglobin 70a that is not bound to oxygen and oxygenated hemoglobin 70b that is bound to oxygen have different light absorption characteristics and show the same extinction coefficient μa. Except for the isosbestic point (the intersection of the hemoglobins 70a and 70b in FIG. 8), a difference occurs in the extinction coefficient μa. If there is a difference in the extinction coefficient μa, the luminance value changes if the oxygen saturation changes even when the light having the same light intensity and the same wavelength is irradiated.

  Since the spectral image PB1 and the spectral image PB2 have the wavelength components of the narrowband light N1 and N2 in which the absorption coefficient μa is different, the luminance values S1 and S2 of the spectral images PB1 and PB2 are changed according to the change in oxygen saturation. Change. Therefore, the oxygen saturation can be calculated by capturing changes in the luminance values S1 and S2. On the other hand, since the spectral image PB3 has a wavelength component of the narrowband light N3 that does not cause a difference in the absorption coefficient μa, the luminance ratio S3 of the spectral image PB3 does not change even if the oxygen saturation changes.

  In addition to the light absorption characteristics of hemoglobin in the blood as described above, the first storage table 63c includes the light reflection characteristics of living tissue and the analysis of a large number of spectral images accumulated in the diagnosis so far. As shown in FIG. 9, the correlation between the luminance coordinate system 71 representing the luminance ratios S1 / S3 and S2 / S3 and the blood vessel information coordinate system 72 representing the oxygen saturation and the blood vessel depth is stored. The luminance coordinate system 71 is an XY coordinate system having two axes XY, and a luminance ratio S1 / S3 is assigned to the X axis, and a luminance ratio S2 / S3 is assigned to the Y axis.

  The blood vessel information coordinate system 72 is a UV coordinate system having two UV axes provided on the luminance coordinate system 71. The U axis is assigned to the blood vessel depth, and the V axis is assigned to the oxygen saturation. The U-axis indicates that the blood vessel is shallower as it goes to the upper right, and the blood vessel is deeper as it goes to the lower left. On the other hand, the V-axis indicates that the oxygen saturation is lower as it goes diagonally up to the left, and the oxygen saturation is higher as it goes down diagonally to the right. In the blood vessel information coordinate system 72, the U axis and the V axis intersect at an intersection P.

  When the luminance ratios S1 / S3 and S2 / S3 calculated by the luminance ratio calculation unit 63b are input, the first calculation unit 63d refers to the correlation stored in the first storage table 63c and inputs the input luminance The oxygen saturation corresponding to the ratios S1 / S3, S2 / S3 is obtained as a provisional temporary oxygen saturation. Here, the provisional oxygen saturation is performed because the spectral images PB1, PB2, and PB3, which are the basis of the luminance ratios S1 / S3, S2 / S3, are only subjected to the simple alignment process that aligns only the central portion. This is because the calculation accuracy of oxygen saturation is low.

  When the luminance ratio S1 / S3 and the luminance ratio S2 / S3 input to the first calculation unit 63d are respectively set as the luminance ratio S1 * / S3 * and the luminance ratio S2 * / S3 *, the first calculation unit 63d Temporary oxygen saturation is calculated as follows. As shown in FIG. 10A, the first calculation unit 63d specifies coordinates (X *, Y *) corresponding to the luminance ratios S1 * / S3 *, S2 * / S3 * in the luminance coordinate system 71. When the coordinates (X *, Y *) are specified, as shown in FIG. 10B, the specified coordinates (X *, Y *) are projected onto the V axis which is the coordinate axis of the oxygen saturation in the blood vessel information coordinate system 72. Then, the coordinate V * is specified. Thereby, the provisional oxygen saturation V * is obtained for one pixel. The first calculation unit 63d repeats such processing for all pixels for one screen, thereby obtaining temporary oxygen saturation data having temporary oxygen saturation for all pixels. Note that the blood vessel depth information U * may be calculated by projecting the coordinates (X *, Y *) onto the U axis, which is the coordinate axis of the blood vessel depth, and specifying the coordinates U *.

  As shown in FIG. 6, the oxygen saturation calculation unit 64 includes a white signal ratio data generation unit 64a, an association unit 64b, a second storage table 64c, a table update unit 64d, and a second calculation unit 64e. I have. The white signal ratio data generation unit 64a obtains the signal ratio B / G between the spectral image PB1 and the spectral image PG1 for each pixel of the white image W, and calculates the signal ratio R / G between the spectral image PR1 and the spectral image PG1. Ask. Thereby, white signal ratio data having signal ratios B / G and R / G for all pixels is obtained.

  The association unit 64 b associates the white signal ratio data with the temporary oxygen saturation data calculated by the temporary oxygen saturation calculation unit 63. Such association is possible, for example, in the case where the distal end portion of the electronic endoscope 11 is directed to a specific observation part and observed in a stationary manner (time and place are limited). If). In the associating unit 64b, first, as shown in FIGS. 11A and 11B, the signal ratios B / G and R / G for the pixels located at the same position between the white signal ratio data and the temporary oxygen saturation data. And provisional oxygen saturation. For example, in the case of the pixel at the first position, the signal ratios B / G = 0.3, R / G = 0.3 are associated with the temporary oxygen saturation 20%. By performing the same associating process for all the pixels of the white signal ratio data and the temporary oxygen saturation data, a temporary oxygen saturation table as shown in FIG. 11C is obtained. In (C), the percentage value in “()” represents oxygen saturation.

  This temporary oxygen saturation table is composed of two-dimensional coordinates in which the signal ratio B / G is assigned to the ordinate and the signal ratio R / G is assigned to the abscissa, and is associated with a predetermined signal ratio on the two-dimensional coordinates. The calculated temporary oxygen saturation is plotted. The temporary oxygen saturation table can also be obtained as a LUT (Look Up Table) as shown in FIG.

  The second storage table 64c stores a correspondence relationship between the signal ratios B / G and R / G of the white image obtained by the diagnosis so far and the oxygen saturation. The table update unit 64d updates the correspondence relationship of the second storage table 64c based on the temporary oxygen saturation table obtained by the association unit 64b. As shown in FIG. 13, when the correspondence relationship in the temporary oxygen saturation table matches (or substantially matches) the correspondence relationship in the second storage table 64c, the correspondence relationship is updated in the second storage. The table 64c is not updated. For example, for the signal ratios B / G = 0.4 and R / G = 0.4, both the temporary oxygen saturation table and the second storage table 64c match at an oxygen saturation of 25%. Do not do. Further, when the correspondence relationship of the temporary oxygen saturation table does not exist on the second storage table 64c, the correspondence relationship is written in the second storage table 64c.

  On the other hand, when the correspondence relationship of the temporary oxygen saturation table does not match the correspondence relationship of the second storage table 64c, the second storage table 64c is updated after performing the averaging process. For this averaging process, the temporary oxygen saturation table and the second storage table 64c have two patterns: the case where the oxygen saturation is the same and the signal ratio is different, and the case where the signal ratio is the same and the oxygen saturation is different. Conceivable. Hereinafter, the former pattern averaging process will be described, but the latter pattern is also the same as the former pattern, and the description thereof will be omitted.

  For example, as shown in FIGS. 14A and 14B, when the oxygen saturation is 30%, the signal ratio in the temporary oxygen saturation table is B / G = 0.5 and R / G = 0. In contrast, the second storage table 64c is different from the signal ratio B / G = 0.3 and R / G = 0.9. In this case, as shown in FIG. 14C, the signal ratios B / G = 0.5 and R / G = 0.7 on the temporary oxygen saturation table and the signal ratio B / G on the second storage table 64c. By averaging G = 0.3 and R / G = 0.9, averaged signal ratios B / G = 0.4 and R / G = 0.8 are obtained. The obtained averaged signal ratios B / G = 0.4 and R / G = 0.8 are associated with the oxygen saturation of 30%. Then, this correspondence (oxygen saturation 30% when B / G = 0.4 and R / G = 0.8) is written in the second storage table 64c.

  Further, as shown in FIG. 14C, with this writing, the correspondence when oxygen saturation is 30% stored on the second storage table 64c is the second storage table 64c after the averaging process. Is erased from Thereby, the correspondence regarding oxygen saturation 30% is updated on the second storage table 64c. The updated second storage table 64c is, for example, the table shown in FIG.

  The second calculation unit 64e calculates the oxygen saturation for each pixel using the white signal ratio data and the updated second storage table 64c. In the second calculation unit 64e, the oxygen saturation corresponding to the signal ratios B / G and R / G of the white signal ratio data is obtained with reference to the correspondence relationship stored in the second storage table 64c. For example, when the second storage table 64c is the case of FIG. 15, the oxygen saturation corresponding to the signal ratio B / G = 0.6 and the signal ratio R / G = 0.8 of the white signal ratio data is “32”. % ". The second calculation unit 64e generates oxygen saturation data having oxygen saturation for all pixels by performing such processing for all pixels.

  As shown in FIG. 6, the image generation unit 69 includes a BGR gain table 76 and a gain value calculation unit 77. As shown in FIG. 16, the BGR gain table 76 has a horizontal axis of oxygen saturation and a luminance value of a blue spectral image PB1, a luminance value of a green spectral image PG1, and a red spectral image PR1 of the white image W. It is composed of an LUT in which gain values gb, gg, and gr for luminance values are assigned to the vertical axis. In the BGR gain table 76, the gain values gb, gg, and gr are all set to 1 when the oxygen saturation is 100% to 60%. On the other hand, when the oxygen saturation is less than 60%, the gain value gr gradually decreases as the oxygen saturation decreases, and the gain values gb and gg gradually increase as the oxygen saturation decreases.

  The gain value calculator 77 reflects the oxygen saturation information on the white image W using the oxygen saturation data generated by the oxygen saturation calculator 64 and the BGR gain table 76. First, a gain value corresponding to the oxygen saturation on the oxygen saturation data is obtained from the BGR gain table 76. The gain value is calculated for all pixels. Then, the calculated gain value is multiplied by the luminance value of the spectral image PB1 of the white image W, the luminance value of the spectral image PG1, and the luminance value of the spectral image PR1. Thereby, an oxygen saturation image is obtained. The generated oxygen saturation image is stored in the frame memory 59 again.

  Since the oxygen saturation image is based on a white image, as shown in FIG. 17, the oxygen saturation image is displayed in a color suitable for a living body in a region 78 where the oxygen saturation is normal, whereas the oxygen saturation is not normal. In the region 79, the color tone of the white image becomes a color that cannot be a living body according to the oxygen saturation. In the present embodiment, since the BGR gain table 76 whose gain value increases or decreases from 1 when the oxygen saturation level is less than 60% is used, the oxygen saturation image has an oxygen saturation level of particularly less than 60% (normal digestion). In 70% of the pixels of the tubal mucosa, the color tone changes to cyan as the oxygen saturation level decreases. The oxygen saturation in a normal state is about 100% for arteries and about 70% for veins.

  In the present embodiment, the gain value is changed when the oxygen saturation is less than 60%. However, the present invention is not limited to this, and the gain value is set to a value lower than 60%. It may be emphasized. On the contrary, it may be set to a value slightly higher than 60% to emphasize a region suspected of being hypoxic as much as possible.

  Note that the oxygen saturation image may reflect color information based on the spectral images PB1, PB2, and PB3 and their combined images instead of the white image. The image generation unit 69 can also generate a blood vessel depth image, similar to the oxygen saturation image, based on the blood vessel depth information obtained by the temporary oxygen saturation calculation unit 63. In this case, it is preferable that a color that can be clearly distinguished is assigned according to the degree of the blood vessel depth.

  In the present embodiment, the pixel value of the white image W is changed according to the oxygen saturation, but the color characteristic values of the white image such as hue, lightness, and saturation are not according to the oxygen saturation but the entire pixel value. May be changed. When changing the hue, lightness, and saturation according to the oxygen saturation, instead of the BGR gain table 76, conversion for converting the oxygen saturation and the pixel value of the white image into hue, lightness, and saturation A hue matrix, a lightness matrix, and a saturation matrix that associate values are used.

  In the above example, the color tone is changed by multiplying the gain value by the image signal. However, an offset value corresponding to the gain value may be added to the log-converted image signal.

  The display control circuit 60 sequentially acquires the oxygen saturation images generated as described above, and displays the sequentially acquired images on the monitor 14 as an oxygen saturation moving image. Since the oxygen saturation movie is generated based on the information on the oxygen saturation obtained from the white image W of one frame, flicker due to positional deviation between frames does not occur, and oxygen in the movie Information about saturation is also accurately displayed.

  Functional information such as oxygen saturation and blood vessel depth may be displayed as text information instead of or in addition to the image. In addition, oxygen saturation is imaged, but the oxygen saturation image may be expressed as “blood volume (sum of oxidized hemoglobin and reduced hemoglobin) × oxygen saturation in place of or in addition to the form shown in the above example. (%) "Which includes an image of an oxygenated hemoglobin index obtained from"% ".

  Next, the operation of the present invention will be described with reference to the flowchart of FIG. When the function information observation mode is set, first, white light W is irradiated into the subject. The reflected image of the subject is picked up by the image pickup device 44 including B pixels, G pixels, and R pixels. As a result, a white image W including the blue spectral image PB1, the green spectral image PG1, and the red spectral image PR1 is obtained.

  Next, narrow band light N2 having a center wavelength of 473 nm is irradiated into the subject, and a reflection image thereof is picked up by the image pickup device 44. Thereby, an image including the spectral image PB2 is obtained. Next, narrow band light N3 having a center wavelength of 405 nm is irradiated into the subject, and a reflected image thereof is picked up by the image pickup device 44. Thereby, an image including the spectral image PB3 is obtained.

  When the image PB3 for the above three frames is obtained, simple alignment between the three spectral images PB1, PB2, and PB3 is performed. By this simple alignment, only the central part of the spectral images PB1 to PB3 is aligned. Next, the luminance ratios S1 / S3 and S2 / S3 between the spectral images that are simply aligned are obtained. The luminance ratio is obtained for all pixels. When the luminance ratio is obtained, the oxygen saturation corresponding to the luminance ratios S1 / S3 and S2 / S3 is obtained as a provisional temporary oxygen saturation from the correlation stored in the first storage table 63c. By obtaining the temporary oxygen saturation for all the pixels, temporary oxygen saturation data is obtained.

  Next, signal ratios B / G and R / G between the spectral images of the white image W are obtained. White signal ratio data is obtained by obtaining the signal ratio of the white image for all the pixels. And white signal ratio data and provisional oxygen saturation data are matched. This association is possible, for example, when it is limited to the same observation site at the same time. By associating the signal ratio of the white image W with the temporary oxygen saturation for all the pixels, the temporary oxygen saturation table is obtained.

  Next, the correspondence relationship in the second storage table 64c is updated based on the temporary oxygen saturation table. In the second storage table 64c, the signal ratio of the white image obtained by the diagnosis so far and the relationship between B / G, R / G and oxygen saturation are stored. Then, the oxygen saturation corresponding to the signal ratios B / G and R / G of the white signal ratio data is obtained from the updated second storage table 64c.

  When the oxygen saturation is obtained for all the pixels, the gain value corresponding to the oxygen saturation of each pixel is specified from the BGR gain table 76. The gain value is specified for all pixels. When the gain value in each pixel is specified, the gain value is multiplied by the luminance value of the spectral image PB1, the luminance value of the spectral image PG1, and the luminance value of the spectral image PR1. Multiplication of gain values is performed for all pixels. Thereby, an oxygen saturation image is obtained. The obtained oxygen saturation image is displayed on the monitor 14 as a moving image.

  In this embodiment, since the alignment of a plurality of spectral images is simply performed, the load on the hardware configuration of the processor device is reduced. Moreover, since the oxygen saturation is calculated from the white image W of one frame and the oxygen saturation image is generated based on the oxygen saturation, a moving image can be displayed without flickering.

[Second Embodiment]
In the above embodiment, the inside of the subject is illuminated using the three laser light sources LD1 to LD3 that respectively emit narrowband light limited to a specific wavelength region in the blue region. The mirror system 91 performs illumination using two laser light sources LD1 and LD2. In this case, instead of the endoscope system 10, for example, an endoscope system 91 shown in FIG. 19 is used. The endoscope system 91 has the same configuration as the endoscope system 10 except that the light source device 92 and the functional image processing unit 102 of the processor device are different. Therefore, in the following, the configuration of the light source device 92 and the functional image processing unit 102 and the related parts will be described, and the description of other configurations will be omitted.

  The light source device 92 includes a semiconductor light source unit 93 and a light source control unit 94 that drives and controls them. The light source control unit 94 controls drive timing and synchronization timing of each unit of the light source device 92.

  The semiconductor light source unit 93 includes two laser light sources LD1 and LD2 that respectively emit narrowband light limited to a specific wavelength region in the blue region. The laser light source LD1 emits narrow band light N1 whose wavelength range is limited to 440 ± 10 nm, preferably 445 nm. The laser light source LD2 emits narrow band light N2 whose wavelength range is limited to 470 ± 10 nm, preferably 473 nm. As the laser light sources LD1 and LD2, InGaN-based, InGaNAs-based, and GaNAs-based laser diodes can be used. Further, as the laser light sources LD1 and LD2, a broad area type laser diode having a wide stripe width (waveguide width) capable of increasing output is preferable.

  The light source control unit 94 controls turning on / off of the laser light sources LD1 and LD2 and the amount of light through the driver 95. The light emitted from the laser light sources LD 1 and LD 2 is guided to the combiner 36 by the optical fiber 96. The combiner 36 is an optical member having a function of multiplexing the light from each optical fiber 96, and couples the optical axes of the light from each optical fiber 96 that selectively enters into one. A phosphor 37 is provided on the downstream side of the combiner 36.

  In the present embodiment, in the normal observation mode, the laser light source LD1 is turned on in accordance with the accumulation timing, and the white light comprising the narrowband light N1 and the fluorescence excited by the phosphor 37 by the narrowband light N1 as illumination light. Light is irradiated onto the observation site, and the reflected light enters the image sensor 44. The imaging element 44 sequentially outputs the imaging signals B, G, and R for one frame in which the luminance values of the B, G, and R pixels are mixed according to the frame rate. Such an imaging operation is repeated while the normal observation mode is set.

  On the other hand, in the functional information observation mode, as shown in FIG. 20, first, the laser light source LD1 is turned on in the first frame, and the narrow band light N1 as illumination light and the fluorescent light excited by the phosphor 37 by the narrow band light N1. The observation site is irradiated with white light W1 (445 nm + phosphor) consisting of the following, and the reflected light is incident on the image sensor 44. Next, the laser light source LD2 is turned on in the second frame, and white light W2 (473 nm + phosphor) composed of narrowband light N2 and fluorescence excited and emitted by the phosphor 37 by the narrowband light N2 is observed as illumination light. The part is irradiated and the reflected light enters the image sensor 44. The imaging element 44 sequentially outputs the imaging signals B, G, and R for one frame in which the luminance values of the B, G, and R pixels are mixed according to the frame rate. Such an imaging operation is repeated while the function information observation mode is set.

  In this functional information observation mode, a white image W1 is obtained by capturing a reflected image of white light W1 in the first frame, and a white image W2 is obtained by capturing a reflected image of white light W2 in the second frame. It is done. The functional image processing unit 102 calculates oxygen saturation based on the green spectral image PG1 and the red spectral image PR1 in the white image W1 and the blue spectral image PB2 in the white image W2. Perform imaging.

  As illustrated in FIG. 21, the functional image processing unit 102 is the same as the functional image processing unit 62 except for the luminance value calculation unit 103, the first storage table 104, and the first calculation unit 105. Therefore, the description of the same part as the functional image processing unit 62 is omitted. In the second embodiment, the white signal ratio data generation unit 64a of the functional image processing unit 102 generates white signal ratio data based on the white image W1.

  The luminance ratio calculation unit 103 calculates the luminance ratio B2 / G1 between the luminance value G1 of the spectral image PG1 and the luminance value B2 of the spectral image PB2 that are simply aligned in the simple alignment processing unit 63a, and is simply aligned. The luminance ratio R1 / G1 between the luminance value G1 of the spectral image PG1 and the luminance value R1 of the spectral image PR1 is calculated. The luminance ratio is calculated for all pixels.

  The first storage table 104 stores a correlation between the signal ratio B2 / G1 and the signal ratio R1 / G1 and the oxygen saturation in the blood vessel. The correlation of the first storage table 104 is obtained from the diagnosis results so far, and is stored in a two-dimensional table in which oxygen saturation contour lines are defined in a two-dimensional space, as shown in FIG. Yes. The positions and shapes of the contour lines are obtained by a physical simulation of light scattering, and are defined to change according to the blood volume. For example, when there is a change in blood volume, the interval between the contour lines becomes wider or narrower. The signal ratios B2 / G1 and R1 / G1 are stored on a log scale.

  The first calculation unit 105 uses the correlation stored in the first storage table 104 and the signal ratio B2 / G1 and the signal ratio R1 / G1 obtained by the luminance ratio calculation unit 103 to provisionally store each pixel. Obtain the provisional oxygen saturation. As shown in FIG. 23, corresponding points P corresponding to the signal ratios B2 * / G1 * and R1 * / G1 * obtained by the luminance ratio calculation unit 103 are specified from the correlation stored in the first storage table 104. When the corresponding point P is between the oxygen saturation = 0% lower limit line 97 and the oxygen saturation = 100% upper limit line 98, the percentage value indicated by the corresponding point P is set as the temporary oxygen saturation level. And For example, in the case of FIG. 23, since the corresponding point P is located on the contour line of 60%, the temporary oxygen saturation is 60%.

  On the other hand, when the corresponding point P is off between the lower limit line 97 and the upper limit line 98, the temporary oxygen saturation is set to 0% when the corresponding point P is located above the lower limit line 97, and the corresponding point P is set to the upper limit. When located below the line 98, the temporary oxygen saturation is set to 100%.

  In the above embodiment, a laser light source composed of a laser diode is exemplified as the semiconductor light source. However, white light source such as a xenon lamp or halogen lamp and white light from the white light source are split into narrowband light N1, N2, and N3. A combination of a spectral filter and a rotary filter having a spectral filter that splits white light into blue B4 light, green G4 light, and red R4 light may be used. In this case, the light source device 201 of the endoscope system 200 shown in FIG. 24 is used instead of the light source device 13 of the endoscope system 10 in the first embodiment. The light generated by the light source device 201 is supplied to the electronic endoscope 202.

  The electronic endoscope 202 has substantially the same configuration as that of the electronic endoscope 11 of the first embodiment, except that a monochrome image sensor 203 without a color filter is used as the image sensor. . The narrow band lights N1, N2, and N3, the blue B4 light, the green G4 light, and the red R4 light are sequentially irradiated in synchronization with the rotation of the rotary filter, and the reflected image is monochrome for each irradiation. Images are taken sequentially by the image sensor 203.

  The light source device 201 includes a white light source 210 that emits broadband light BB (400 to 700 nm), a rotation filter 212 that separates the broadband light BB from the white light source 210 into light of three colors B, G, and R, and a rotation filter 212. A motor 213 that rotates the rotary filter 212 at a constant rotation speed, and a shift unit 214 that shifts the rotary filter 212 in the radial direction.

  The white light source 210 includes a light source body 210a that emits the broadband light BB and a diaphragm 210b that adjusts the amount of the broadband light BB. The light source body 210a includes a xenon lamp, a halogen lamp, a metal halide lamp, and the like. The opening degree of the aperture 210b is adjusted by a light amount control unit (not shown).

  As shown in FIG. 25, the rotary filter 212 rotates about the rotation axis connected to the motor 213 as the rotation center. The rotation filter 212 is provided with a first filter region and second filter regions 220 and 221 along the radial direction in order from a rotation center with a rotation axis. One of the first and second filter regions 220 and 221 is set on the optical path of the broadband light BB depending on the mode. The first filter region 220 is set on the optical path of the broadband light BB in the normal observation mode, and the second filter region 221 is set on the optical path of the broadband light BB in the function information observation mode. Switching between the filter regions 220 and 221 is performed by causing the shift unit 214 to shift the rotary filter 212 in the radial direction.

  In the first filter region 220, a B filter portion 220a, a G filter portion 220b, and an R filter portion 220c are provided in a fan-shaped region having a central angle of 120 °, respectively. The B filter unit 220a transmits B light in the blue band (380 to 500 nm) from the broadband light BB, and the G filter unit 220b transmits G light in the green band (450 to 630 nm) from the broadband light BB, and the R filter unit 220c. Transmits the R light in the red band (580 to 760 nm) from the broadband light BB. Therefore, B light, G light, and R light are sequentially emitted from the rotary filter 212 by the rotation of the rotary filter 212. These B light, G light, and R light are incident on the ride guide 43 through the condenser lens 216.

  The second filter region 221 includes a B4 filter unit 221a, a G4 filter unit 221b, an R4 filter unit 221c, a B3 filter unit 221d, a B1 filter unit 221e, and a B2 filter unit 221f. The B3 filter unit 221d transmits blue narrowband light N3 having a wavelength range of 400 ± 10 nm from the broadband light BB. The B1 filter unit 221e transmits the blue narrowband light N1 having a wavelength range of 440 ± 10 nm from the broadband light BB. The B2 filter unit 221f transmits the blue narrowband light N2 having a wavelength range of 470 ± 10 nm from the broadband light BB.

  On the other hand, the B4 filter unit 221a, the G4 filter unit 221b, and the R4 filter unit 221c are similar to the B filter unit 220a, the G filter unit 220b, and the R filter unit 220c, and the B4 filter unit 221a is B4 in the blue band (380 to 500 nm). The G4 filter unit 221b transmits G4 light in the green band (450 to 630 nm), and the R4 filter unit 221c transmits R4 light in the red band (580 to 760 nm). Therefore, as the rotary filter 112 rotates, B4 light, G4 light, R4 light, and blue narrowband light N3, N1, and N2 are sequentially emitted from the rotary filter 212. Each of these lights enters the ride guide 43 through the condenser lens 216.

  In the normal observation mode, as shown in FIG. 26A, image light of three colors B, G, and R is sequentially imaged and electric charges are accumulated, and surface sequential imaging signals B, G, and R are based on the accumulated electric charges. Are output sequentially. This series of operations is repeated while the normal observation mode is set. On the other hand, in the functional information observation mode, as shown in FIG. 28B, the image light of blue narrowband light N3, N1, N2, B4 light, G4 light, and R4 light is sequentially imaged and electric charges are accumulated. Based on the charges, the surface sequential imaging signals N3, N1, N2, B4, G4, and R4 are sequentially output. Such an operation is repeated while the function information observation mode is set.

  The normal light image processing unit 61 in the processor device 12 generates a white image W based on the frame sequential imaging signals B, G, and R. On the other hand, the functional image processing unit 62 generates an oxygen saturation image based on the white image generated from the frame sequential imaging signals B4, G4, and R4 and the frame sequential imaging signals N3, N1, and N2. Here, N1 / N3 is used as the luminance ratio corresponding to the luminance ratio S1 / S3 of the first embodiment, and N2 / N3 is used as the luminance ratio corresponding to the luminance ratio S2 / S3 of the first embodiment. Accordingly, the first storage table 63c stores the correlation between the luminance ratios N1 / N3 and N2 / N3 and the oxygen saturation. Further, among the signal ratios of the white image W, B4 / G4 is used as the signal ratio corresponding to the signal ratio B / G of the first embodiment, and the signal ratio corresponding to the signal ratio R / G of the first embodiment. , R4 / G4 is used. Accordingly, the correspondence relationship between the signal ratios B4 / G4 and R4 / G4 and the oxygen saturation is stored in the second storage table 64c. Other than that, processing is performed in the same procedure as in the first embodiment.

  In the above embodiment, the correspondence between the white image and the oxygen saturation is stored in advance in the second storage table, but this correspondence may vary greatly depending on the patient. At the start, it is preferable to reset all the correspondences stored in the second storage table.

  In the above embodiment, the second storage table is updated every time the temporary oxygen saturation is calculated. However, the second storage table may not be updated under specific conditions. In this case, irradiation and imaging of the narrow band lights N2 and N3 are not performed, and only irradiation and imaging of the white light W are performed. That is, the oxygen saturation is calculated and imaged using only the white image W and the second storage table.

  In the above embodiment, the example in which the light source device and the processor device are configured separately has been described, but the two devices may be configured integrally. The present invention also relates to a system comprising an ultrasonic endoscope in which an image sensor and an ultrasonic transducer are built in the tip and a processor device for performing image processing, a system comprising a capsule endoscope and a processor device for performing image processing, etc. The present invention can also be applied to other types of endoscope systems.

10, 91, 200 Endoscope system 14 Monitor 31, 93 Semiconductor light source unit 32, 94 Light source controller 44 Image sensor 62, 102 Functional image processor 63 Temporary oxygen saturation calculator 63a Simple alignment processor 64 Oxygen saturation Calculation unit 64a White signal ratio data generation unit 64b association unit 64c second storage table 64e second calculation unit

Claims (12)

Image acquisition means for acquiring a first image having a broadband component;
Correspondence storage means for preliminarily storing the correspondence between the oxygen saturation of blood hemoglobin and the first image;
Oxygen saturation calculation means for obtaining oxygen saturation corresponding to the first image acquired by the image acquisition means from the correspondence storage means;
An endoscope system comprising: a moving image display unit that displays a moving image of an oxygen saturation image obtained by imaging the oxygen saturation obtained by the oxygen saturation calculating unit. The image acquisition means acquires, in addition to the first image, a second image having wavelength components having different absorption coefficients of oxyhemoglobin and reduced hemoglobin,
The oxygen saturation calculating means includes
A temporary oxygen saturation calculating unit that calculates temporary oxygen saturation based on the first image and the second image;
An association unit for associating the temporary oxygen saturation with the first image;
An update unit that updates the correspondence stored in the correspondence storage unit by reflecting the correspondence between the temporary oxygen saturation and the first image in the correspondence storage unit;
The endoscope system according to claim 1, further comprising: an oxygen saturation calculation unit that obtains an oxygen saturation corresponding to the first image acquired by the image acquisition unit from the correspondence storage unit.   The endoscope system according to claim 2, wherein the temporary oxygen saturation calculating unit obtains the temporary oxygen saturation after aligning only a central portion between the first and second images.   When the correspondence between the temporary oxygen saturation and the first image does not match the correspondence in the correspondence storage unit, the update unit performs an averaging process based on the correspondence and then performs the correspondence 4. The endoscope system according to claim 2, wherein the relation storage means is updated. The first image includes a plurality of spectral images having different wavelength components,
The endoscope system according to any one of claims 1 to 4, wherein the correspondence relationship storage unit stores a correspondence relationship between a luminance ratio between predetermined spectral images and the oxygen saturation. The plurality of spectral images are a blue spectral image, a green spectral image, and a red spectral image,
The correspondence storage means stores the correspondence between the first signal ratio between the blue spectral image and the green spectral image, the second signal ratio between the red spectral image and the green spectral image, and the oxygen saturation. 6. The endoscope system according to claim 5, wherein the endoscope system is stored. Provided with illumination means for irradiating the subject with white light,
The image acquisition means acquires the blue spectral image, the green spectral image, and the red spectral image by capturing the reflected image of the white light with a color imaging device. Item 5. The endoscope system according to Item 6.   8. The endoscope system according to claim 7, wherein the white light includes blue narrow band light and fluorescence obtained by wavelength conversion of the blue narrow band light by a wavelength conversion member. Provided with illumination means for sequentially irradiating the subject with blue light, green light, and red light,
The image acquisition means acquires the blue spectral image, the green spectral image, and the red spectral image by sequentially capturing a reflected image of light of each color with a monochrome imaging device. The endoscope system according to claim 6. In a processor device of an endoscope system connected to an electronic endoscope that acquires a first image having a broadband component,
Correspondence storage means for preliminarily storing the correspondence between the oxygen saturation of blood hemoglobin and the first image;
Oxygen saturation calculating means for obtaining oxygen saturation corresponding to the first image acquired by the electronic endoscope from the correspondence storage means;
A processor device for an endoscope system, comprising: a display control means for displaying an oxygen saturation image obtained by imaging the oxygen saturation obtained by the oxygen saturation calculation means on a display means. Image acquisition means, the steps of get the first image having a wide band component,
The oxygen saturation calculation means obtains the oxygen saturation corresponding to the first image acquired by the image acquisition means from the correspondence storage means for previously storing the correspondence relation between the oxygen saturation of blood hemoglobin and the first image. Steps,
A method of operating an endoscope system , wherein the moving image display means includes a step of displaying a moving image of an oxygen saturation image obtained by imaging the oxygen saturation obtained by the oxygen saturation calculating means. In an image processing program for processing an image acquired by an image acquisition means of an electronic endoscope,
Computer
Oxygen saturation for obtaining oxygen saturation corresponding to the first image acquired by the image acquisition means from correspondence storage means for storing in advance the correspondence between the first image having a broadband component and the oxygen saturation of blood hemoglobin An image processing program that functions as a display control unit for displaying an oxygen saturation image obtained by imaging the oxygen saturation obtained by the calculation unit and the oxygen saturation calculation unit on the display unit as a moving image.

Images