WO2014156604A1 - Endoscope system, operational method therefor and processor device - Google Patents

Abstract

Provided are: an endoscope system which accurately calculates oxygen saturation of blood hemoglobin even when there are regions with different brightness in an image; an operational method therefor; and a processor device. A first white light that includes a first blue laser light and a first fluorescence and a second white light that includes a second blue laser light and a second fluorescence are applied into a subject alternately. Out of image signals obtained by imaging the subject with an image sensor, the B1 image signal, G2 image signal, R1 image signal and R2 image signal are used to calculate oxygen saturation. From the B1 image signal and G2 image signal, displacement of the subject is calculated. On the basis of this displacement of the subject, the R1 image signal and R2 image signal are aligned. From the aligned R1 image signal and R2 image signal, a reference signal ratio (R2/R1) is calculated. On the basis of this reference signal ratio, the G2 image signal or R2 image signal is corrected. On the basis of the B1 image signal and the corrected G2 image signal or R2 image signal, the oxygen saturation is calculated.

Description

ENDOSCOPE SYSTEM, OPERATION METHOD THEREOF, AND PROCESSOR DEVICE

The present invention relates to an endoscope system for obtaining biological function information on oxygen saturation of blood hemoglobin from an image signal obtained by imaging in a sample, an operation method thereof, and a processor apparatus.

In the medical field, diagnosis is generally performed using an endoscope system provided with a light source device, an endoscope, and a processor device (JP 2012-125402 A, JP 2013-13656 A) JP-A-2001-218217, JP-A-2011-233844, JP-A-2009-135907, JP-A-2010-227253). Further, in recent years, among the biological function information, diagnosis of a lesioned part using oxygen saturation of blood hemoglobin is being performed. As a method of acquiring the oxygen saturation of blood hemoglobin, the first signal light having different absorption coefficients of oxygenated hemoglobin and reduced hemoglobin and the second signal light of a wavelength range different from the first signal light are alternately displayed in the mucous membrane. The blood vessel is irradiated and the reflected light of the first and second signal light is detected by the image sensor at the tip of the endoscope.

The measurement signal ratio indicating the ratio of the first signal image signal corresponding to the reflected light of the first signal light detected by the image sensor and the second signal image signal corresponding to the reflected light of the second signal light is Under conditions where mirror automatic exposure control (AE) is ideally working, a constant value is maintained if there is no change in oxygen saturation in the blood vessel. On the other hand, if the oxygen saturation changes, the measurement signal ratio changes accordingly. Therefore, the oxygen saturation can be calculated from the measurement signal ratio.

However, when the automatic exposure control becomes unstable, such as when the distance between the tip of the endoscope and the sample suddenly changes, the intensity ratio of the reflected light of the first signal light and that of the second signal light (between frames) The intensity ratio may deviate from the predetermined interframe intensity ratio (reference interframe intensity ratio). In this case, even if there is no change in the oxygen saturation, the measurement signal ratio also changes with the change in the inter-frame intensity ratio. This is one of the factors that reduce the calculation accuracy of the oxygen saturation.

Therefore, in JP 2012-125402 A, even if the inter-frame intensity ratio deviates from the inter-frame intensity ratio due to the destabilization of automatic exposure control, the measurement signal ratio does not fluctuate thereby. The first signal image signal or the second signal image signal is corrected according to the change in the inter-frame intensity ratio.

In JP-A-2012-125402, in order to grasp changes in the intensity ratio between frames, the first reference light (the fluorescence emitted from the fluorescent substance detected by the R pixel of the image sensor at the same time as the first signal light) Component) and the second reference light (the red component detected in the R pixel of the image sensor among the fluorescence emitted from the fluorescent substance) is emitted simultaneously with the second signal light. Then, with reference to the reference signal ratio indicating the ratio between the first reference image signal corresponding to the first reference light and the second reference image signal corresponding to the second reference light, the first signal is generated for each pixel. The image signal for the second signal or the image signal for the second signal is corrected.

The reference signal ratio is calculated from the average value of the first reference image signal and the average value of the second reference image signal. Therefore, if there is a region with greatly different brightness in the image, such as when a partial region in the screen becomes darker than the other regions, correct correction is performed even using the reference signal ratio. You may not be able to In such a situation, when the tip of the endoscope is curved to perform a turning operation (when a part of the area in the screen approaches the sample and the other areas move away), or when the tip of the endoscope is It occurs, for example, when a bump suddenly appears in front. Therefore, even if there are regions of different brightness in the image, it is required to accurately calculate the oxygen saturation by correcting the signal image signal accurately according to the fluctuation of the inter-frame intensity ratio. ing.

An object of the present invention is to provide an endoscope system capable of accurately calculating the oxygen saturation of blood hemoglobin even if there are regions of different brightness in an image, and an operation method and processor apparatus thereof. I assume.

In order to achieve the above object, an endoscope system of the present invention includes a first light source, a second light source, a light source control unit, an imaging unit, a first alignment unit, and a second alignment unit. A reference information calculation unit, a correction unit, and a biological function information calculation unit are provided. The first light source emits a first illumination light including a first signal light and a first reference light. The second light source emits second illumination light including second signal light having a wavelength range different from that of the first signal light and second reference light. The light source control unit controls the irradiation timing of the first illumination light and the second illumination light so that the first illumination light and the second illumination light are alternately irradiated to the subject. The imaging unit copes with the first signal light by imaging the reflected light of the first illumination light into the first signal light and the first reference light while the illumination light illuminates the specimen with the first illumination light. The first signal image signal is output, and the first reference image signal corresponding to the first reference light is output. In addition, the imaging unit separates the reflected light of the second illumination light into the second signal light and the second reference light during imaging of the second illumination light during imaging of the sample by the second illumination light. The second signal image signal corresponding to the second reference light is output, and the second reference image signal corresponding to the second reference light is output. The first alignment unit calculates the amount of positional deviation between the first signal image signal and the second signal image signal, and performs alignment between the signal image signals. The second alignment unit aligns the first reference image signal and the second reference image signal based on the positional shift amount. The reference information calculation unit calculates, for each pixel, reference information related to the intensities of the first and second signal lights based on the first reference image signal and the second reference image signal that have been aligned. The correction unit corrects the first signal image signal or the second signal image signal based on the reference information. The biological function information calculation unit calculates biological function information based on the corrected first signal image signal or the second signal image signal.

The high-frequency component extraction unit for performing high-frequency filtering to extract high-frequency components to the first signal image signal and the second signal image signal is provided, and the first alignment unit is an image signal for the first signal after high frequency filtering It is preferable that the calculation of the positional deviation amount and the alignment be performed on the basis of the second signal image signal. A low frequency component extraction unit for performing low frequency filtering to extract low frequency components to the first reference image signal and the second reference image signal which have been aligned is provided, and the second alignment unit is configured to perform low frequency filtering It is preferable to align the later first reference image signal and the second reference image signal.

Reference points are set in a plurality of areas of one image signal among the first signal image signal and the second signal image signal, and a search point is set at a position corresponding to the reference point in the other image signal. A search condition setting unit for setting is provided, and the first alignment unit performs a detection process for detecting a target point having a feature quantity closest to a reference point by moving a search point within a predetermined search range, and a positional deviation The amount is preferably a movement amount of the search point when the target point is detected.

It is preferable to set a reference point and a search point in a part other than the dark part in the dark area in the dark area where the dark part exists among the plurality of areas. It is preferable to make the search range in the case where the distance to the sample is a certain value or more wider than the search range in the case where the distance is less than a certain value. It is preferable to provide a sample enlargement unit that enlarges the sample, and make the search range when the sample enlargement unit is not used wider than the search range when the sample enlargement unit is used.

The imaging unit includes a plurality of first pixels that receive the first signal light and output a first signal image signal, and a plurality of second pixels that receive a second signal light and output a second signal image signal. It is preferable to have a color image sensor provided with a plurality of third pixels that receive the first or second reference light and output a first reference image signal or a second reference image signal.

Preferably, the first and second signal lights have a wavelength range shorter than that of the first and second reference lights. Preferably, the first reference light and the second reference light have the same waveform, and the intensity ratio of the first reference light and the second reference light is the same at any wavelength.

The biological function information is the oxygen saturation calculated based on the measurement signal ratio between the first signal image signal and the second signal image signal after correction, and the reference information is the first reference image signal It is a reference signal ratio that indicates the ratio between the second reference image signals, and the reference signal ratio is an interframe that indicates the ratio of the intensity of the reflected light of the first illumination light and the intensity of the reflected light of the second illumination light. It is preferable to change in accordance with the intensity ratio.

In the present invention, the processor device is connected to the endoscope system. The endoscope system includes a first light source, a second light source, a light source control unit, and an imaging unit. The processor device includes a first alignment unit, a second alignment unit, and reference information calculation. And a correction unit, and a biological function information calculation unit. The first light source emits a first illumination light including a first signal light and a first reference light. The second light source emits second illumination light including second signal light having a wavelength range different from that of the first signal light and second reference light. The light source control unit controls the generation timing of the first illumination light and the second illumination light so that the first illumination light and the second illumination light are alternately irradiated to the subject. The imaging unit copes with the first signal light by imaging the reflected light of the first illumination light into the first signal light and the first reference light while the illumination light illuminates the specimen with the first illumination light. Outputting the first signal image signal and outputting the first reference image signal corresponding to the first reference light, and the imaging unit generates a second illumination signal during illumination of the sample by the second illumination light. The second signal light image signal corresponding to the second signal light is output by separating the light of the reflected light into the second signal light and the second reference light for imaging, and the second light corresponding to the second reference light 2 Output the reference image signal.

The operating method of the endoscope system according to the present invention comprises a control step, an imaging step, a first alignment step, a second alignment step, a reference information calculation step, a correction step, and a biological function information calculation step. Have. In the control step, the light source controller controls the first illumination light including the first signal light and the first reference light, and the second illumination light including the second signal light and the second reference light different in wavelength range from the first signal light. The generation timings of the first illumination light and the second illumination light are controlled so as to occur at different timings. In the imaging step, the imaging unit separates the reflected light of the first illumination light into the first signal light and the first reference light during imaging of the first illumination light to obtain the first light. The first signal image signal corresponding to the signal light is output, and the first reference image signal corresponding to the first reference light is output. In the imaging step, the second signal light is captured by wavelength-dividing the reflected light of the second illumination light into the second signal light and the second reference light during illumination of the sample by the second illumination light. The second signal image signal corresponding to the second reference light is output, and the second reference image signal corresponding to the second reference light is output. In the first alignment step, the first alignment unit calculates the amount of positional deviation between the first signal image signal and the second signal image signal, and performs alignment between the signal image signals. In the second alignment step, the second alignment unit aligns the first reference image signal and the second reference image signal based on the positional shift amount. In the reference information calculation step, the reference information calculation unit refers to the reference information on the intensity of the first and second signal light for each pixel based on the aligned first reference image signal and the second reference image signal. calculate. In the correction step, the correction unit corrects the first signal image signal or the second signal image signal based on the reference information. In the biological function information calculation step, the biological function information calculation unit calculates biological function information based on the corrected first signal image signal or the second signal image signal.

According to the present invention, the image signal for the first or second signal is accurately corrected according to the fluctuation of the intensity ratio of the first and second signal light even if there is a region with different brightness in the image. Thus, the oxygen saturation can be accurately calculated.

It is an external view of an endoscope system. It is a block diagram of an endoscope system of a 1st embodiment. It is a graph which shows the emission spectrum of 2nd white light light-emitted at the time of normal observation mode. It is a graph which shows the emission spectrum of the 1st and 2nd white light which light-emits at the time of special observation mode. It is an explanatory view for comparing the luminescence spectrum of the 1st and 2nd white light. It is a graph which shows the spectral transmission factor of a BGR color filter. It is explanatory drawing which shows the imaging control at the time of the normal observation mode in 1st Embodiment. It is an explanatory view showing image pick-up control at the time of special observation mode in a 1st embodiment. It is a block diagram of an oxygen saturation image generation part. It is explanatory drawing which shows the processing flow in a signal correction | amendment part. It is an explanatory view showing a reference point. It is an explanatory view showing a search point and a goal point. It is explanatory drawing which shows the setting method of the reference point in case the brightness of each area is substantially the same, and a search point. FIG. 6 is a cross-sectional view of the lumen when there is no protrusion in front of the tip of the endoscope. It is explanatory drawing which shows the setting method of the reference point in case there is an area where a dark space exists, and a search point. FIG. 6 is a cross-sectional view of the lumen in the case where a protuberance is present in front of the distal end of the endoscope. 5 is an explanatory view showing a method of setting a search range X. FIG. FIG. 6 is an explanatory view showing a method of setting a search range Y. It is a graph showing correlation with measurement signal ratio B1 / G2, R2 / G2, and oxygen saturation. It is a graph which shows the absorption coefficient of oxyhemoglobin and reduced hemoglobin. It is explanatory drawing which shows the method of calculating oxygen saturation with reference to the correlation of FIG. It is a flowchart showing a series of flows of the present invention. It is a block diagram of the endoscope system by which fluorescent substance was provided in the light source device. It is a block diagram of an endoscope system of a 2nd embodiment. It is explanatory drawing which shows the imaging control at the time of the normal observation mode in 2nd Embodiment. It is an explanatory view showing image pick-up control at the time of special observation mode in a 2nd embodiment. It is a block diagram of an endoscope system of a 3rd embodiment. It is a top view of the rotation filter of a 3rd embodiment. It is a graph which shows the spectral transmission factor of BPF of 3rd Embodiment. It is explanatory drawing which shows the imaging control at the time of the normal observation mode in 3rd Embodiment. It is an explanatory view showing image pick-up control at the time of special observation mode in a 3rd embodiment. It is a block diagram of the endoscope system of a 4th embodiment. It is a top view of the rotation filter of a 4th embodiment. It is a graph which shows the spectral transmission factor of BPF of 4th Embodiment. It is explanatory drawing which shows the imaging control at the time of the normal observation mode in 4th Embodiment. It is an explanatory view showing image pick-up control at the time of special observation mode in a 4th embodiment.

First Embodiment
As shown in FIG. 1, the endoscope system 10 of the first embodiment includes an endoscope 12, a light source device 14, a processor device 16, a monitor 18, and a console 20. The endoscope 12 is optically connected to the light source device 14 and electrically connected to the processor device 16. The endoscope 12 has an insertion portion 21 to be inserted into a sample, an operation portion 22 provided at a proximal end portion of the insertion portion, and a bending portion 23 and a distal end portion 24 provided on the distal end side of the insertion portion 21. doing. By operating the angle knob 22a of the operation unit 22, the bending unit 23 bends. With this bending operation, the tip 24 is oriented in the desired direction.

In addition to the angle knob 22a, the operation unit 22 is provided with a mode switching switch 22b and a zoom operation unit 22c. The mode switching SW 22 b is used to switch between the normal observation mode and the special observation mode. The normal observation mode is a mode in which a normal light image obtained by forming a full color image of the inside of a subject is displayed on the monitor 18. The special observation mode is a mode in which an oxygen saturation image obtained by imaging the oxygen saturation of blood hemoglobin in the sample is displayed on the monitor 18. The zoom operation unit 22 c drives a zooming lens (specimen enlargement unit) 47 (see FIG. 2) in the endoscope 12 and is used for a zoom operation to magnify the specimen.

The processor unit 16 is electrically connected to the monitor 18 and the console 20. The monitor 18 outputs and displays image information and the like. The console 20 functions as a UI (user interface) that receives an input operation such as function setting. Note that an external recording unit (not shown) that records image information and the like may be connected to the processor device 16.

As shown in FIG. 2, the light source device 14 includes a first blue laser light source (473 LD) 34 that emits a first blue laser light having a central wavelength of 473 nm and a second blue laser light source that emits a second blue laser light having a central wavelength of 445 nm. (445 LD) 34 as a light source. The light emission from the semiconductor light emitting elements of each of the light sources 34 and 36 is individually controlled by the light source control unit 40, and the light quantity ratio of the emitted light of the first blue laser light source 34 and the emitted light of the second blue laser light source 36 Is changeable. In the normal observation mode, the light source control unit 40 drives the second blue laser light source 36 to emit the second blue laser light.

On the other hand, in the case of the special observation mode, the first blue laser light source 34 and the second blue laser light source 36 are alternately turned on at an interval of one frame. Thereby, the first blue laser light and the second blue laser light are alternately emitted. The half-width of the first and second blue laser beams is preferably about ± 10 nm. In addition, as the first blue laser light source 34 and the second blue laser light source 36, a broad area type InGaN-based laser diode can be used, and an InGaNAs-based laser diode or a GaNAs-based laser diode can also be used. In addition, a light emitter such as a light emitting diode may be used as the light source.

The laser beams emitted from the light sources 34 and 36 are incident on the light guide (LG) 41 via optical members such as a condenser lens, an optical fiber, and a multiplexer (none of which are shown). The light guide 41 is incorporated in a universal cord (not shown) that connects the light source device 14 and the endoscope 12. The light guide 41 propagates the laser light from each of the light sources 34 and 36 to the tip 24 of the endoscope 12. As the light guide 41, a multimode fiber can be used. As an example, it is possible to use a small diameter fiber cable with a core diameter of 105 μm, a cladding diameter of 125 μm, and a diameter of 0.3 to 0.5 mm including a protective layer to be an outer shell.

The distal end portion 24 of the endoscope 12 has an illumination optical system 24 a and an imaging optical system 24 b. A fluorescent body 44 and an illumination lens 45 are provided in the illumination optical system 24 a. The laser light from the light guide 41 is incident on the phosphor 44. In the fluorescent substance 44, the fluorescent substance 44 emits fluorescence by being irradiated with the first or second blue laser light. In addition, part of the first or second blue laser light passes through the phosphor 44 as it is. The light emitted from the phosphor 44 is irradiated into the sample through the illumination lens 45.

Here, in the normal observation mode, since the second blue laser light is incident on the phosphor 44, the second white light as shown in FIG. 3 is irradiated into the sample. The second white light is composed of the second blue laser light and the green to red second fluorescence excited and emitted from the phosphor 44 by the second blue laser light. Therefore, the second white light has a wavelength range extending to the entire visible light range.

On the other hand, in the special observation mode, when the first blue laser light and the second blue laser light are alternately incident on the phosphor 44, as shown in FIG. 4, the first white light and the second white light are alternately emitted. Do. The alternately emitted first and second white light is irradiated into the sample. The first white light is composed of a first blue laser light and a first fluorescence of green to red which is excited to emit light from the phosphor 44 by the first blue laser light. Therefore, the signal light has a wavelength range extending to the entire visible light range. The second white light is similar to the second white light emitted in the normal observation mode. As shown in FIG. 5, the first fluorescence and the second fluorescence have the same waveform. Further, the interframe intensity ratio (I2 (λ) / I1 (λ)), which indicates the ratio of the intensity of the first fluorescence (I1 (λ)) to the intensity of the second fluorescence (I2 (λ)), has any wavelength λ Also substantially the same (for example, I2 (λ1) / I1 (λ1) = I2 (λ2) / I1 (λ2)).

Here, since the interframe intensity ratio (I2 (λ) / I1 (λ)) affects the calculation accuracy of the oxygen saturation, the reference interframe intensity ratio set in advance by the light source control unit 40 It is controlled with high precision so as to maintain. However, since the light source control unit 40 performs control based on the image signal acquired by the image sensor 48 after the emission of the first and second white light, the distance between the tip 24 of the endoscope 12 and the specimen changes rapidly In such cases, control by the light source control unit 40 may be unstable. In the present embodiment, as described above, even when the control by the light source control unit 40 becomes unstable, the processor device 16 performs image processing to eliminate the instability.

In the present invention, the “first signal light” corresponds to the “first blue laser light”, and the “first reference light” is a “red component to be received by the R pixel of the image sensor 48 in the first fluorescence”. It corresponds to "light of". Therefore, the “first light source” of the present invention includes the first blue laser light source 34 and the phosphor 44. Further, in the present invention, the “second signal light” corresponds to “the light of the green component received by the G pixel of the image sensor 48 in the second fluorescence”, and the “second reference light” corresponds to the “second fluorescence”. Of the red component light received by the R pixel of the image sensor 48. Therefore, the “second light source” of the present invention includes the second blue laser light source 36 and the phosphor 44.

Note that the phosphor 44 absorbs a part of the first and second blue laser light, and emits plural colors of green to red (for example, YAG-based phosphor or BAM (BaMgAl ₁₀ O ₁₇ )). Etc.) are preferably contained. When the semiconductor light emitting element is used as an excitation light source of the phosphor 44 as in this configuration example, high intensity first and second white light can be obtained with high luminous efficiency, and the intensity of the white light can be easily adjusted. In addition, changes in color temperature and chromaticity can be reduced.

As shown in FIG. 2, the imaging optical system 24 b of the endoscope 12 has an objective lens 46, a zooming lens 47, and an image sensor 48. Reflected light from the subject is incident on the image sensor 48 through the objective lens 46 and the zooming lens 47. Thereby, a reflection image of the subject is formed on the image sensor 48. The zooming lens 47 moves between the tele end and the wide end by operating the zoom operation unit 22 c. When the zooming lens 47 moves to the tele end side, the reflection image of the subject is enlarged, while by moving to the wide end side, the reflection image of the subject is reduced.

An image sensor (imaging unit) 48 is a color image sensor, which captures a reflection image of a subject and outputs an image signal. Preferably, the image sensor 48 is a charge coupled device (CCD) image sensor, a complementary metal-oxide semiconductor (CMOS) image sensor, or the like. The image sensor used in the present invention is an RGB image sensor having RGB pixels in which RGB color filters are provided on the imaging surface, and photoelectric conversion is performed on each channel to obtain R, G, B image signals of three colors. Output.

As shown in FIG. 6, the B color filter has a spectral transmittance of 380 to 560 nm, the G color filter has a spectral transmittance of 450 to 630 nm, and the R color filter has a spectrum of 580 to 760 nm. It has a transmittance. Therefore, when the second white light is irradiated into the sample in the normal observation mode, part of the green component of the second blue laser light and the second fluorescence is incident on the B pixel, and the second fluorescence is on the G pixel A part of the green component of R.sub.2 is incident, and the red component of the second fluorescence is incident to the R pixel. However, since the second blue laser light has a significantly higher emission intensity than the second fluorescence, most of the B image signal output from the B pixel is occupied by the reflected light component of the second blue laser light.

On the other hand, when the first white light is irradiated into the sample in the special observation mode, part of the green component of the first blue laser light and the first fluorescence is incident on the B pixel and the first fluorescence is on the G pixel A part of the green component of R.sub.1 is incident, and the red component of the first fluorescence is incident to the R pixel. However, since the first blue laser light has extremely higher emission intensity than the first fluorescence, most of the B image signal is occupied by the reflected light component of the first blue laser light. The light incident component at the BGR pixel when the second white light is irradiated into the sample in the special observation mode is the same as that in the normal observation mode.

The image sensor 48 may be a so-called complementary color image sensor provided with complementary color filters of cyan (C), magenta (M), yellow (Y) and green (G) on the imaging surface. In the case of a complementary color image sensor, an image signal of three colors RGB can be obtained by color conversion from an image signal of four colors CMYG. In this case, any of the endoscope 12, the light source device 14 or the processor device 16 needs to be provided with color conversion means for performing color conversion of the CMYG four color image signals to the RGB three color image signals. is there.

The imaging control unit 49 performs imaging control of the image sensor 48 according to the observation mode. As shown in FIG. 7A, in the normal observation mode, the inside of the sample illuminated by the second white light is imaged by the color image sensor 48 every period of one frame. Thus, the image sensor 48 outputs RGB image signals for each frame. As shown in FIG. 7B, in the special observation mode, the inside of the sample illuminated with the first white light is imaged by the color image sensor 48 in the first frame, and the second white light is imaged in the second frame. The illuminated sample is imaged by a color image sensor 48. Thereby, in the first frame, the R1 image signal, the G1 image signal, and the B1 image signal are output from the image sensor 48, and in the second frame, the R2 image signal, the G2 image signal, and the B2 image signal from the image sensor 48. Output. The period for one frame of the image sensor 48 includes an accumulation period for photoelectrically converting and accumulating the reflected light from the sample and a readout period for reading out the charges accumulated thereafter and outputting an image signal.

As shown in FIG. 2, the image signal output from the image sensor 48 is transmitted to the CDS / AGC circuit 50. The CDS-AGC circuit 50 performs correlated double sampling (CDS) and automatic gain control (AGC) on an image signal which is an analog signal. A gamma conversion unit 51 performs gamma conversion on the image signal that has passed through the CDS-AGC circuit 50. Thereby, an image signal having a gradation suitable for an output device such as the monitor 18 can be obtained. The image signal after gamma conversion is converted into a digital image signal by an A / D converter (A / D converter) 52. The A / D converted digital image signal is input to the processor unit 16.

The processor device 16 includes a receiving unit 54, an image processing switching unit 60, a normal light image processing unit 62, a special light image processing unit 64, and an image display signal generating unit 66. The receiving unit 54 receives the digital image signal from the endoscope 12. The receiving unit 54 includes a DSP (Digital Signal Processor) 56 and a noise removing unit 58. The DSP 56 performs color correction processing on the digital image signal. The noise removing unit 58 removes noise from the digital image signal by performing noise removing processing (for example, moving average method, median filter method, and the like) on the digital image signal subjected to color correction processing and the like by the DSP 56. The digital image signal from which the noise has been removed is transmitted to the image processing switching unit 60.

The image processing switching unit 60 transmits the digital image signal to the normal light image processing unit 62 when the normal observation mode is set by the mode switching SW 22 b, and when the special observation mode is set, the image processing switching unit 60 The image signal is transmitted to the special light image processing unit 64. In the present invention, for distinction, a digital image signal before image processing by the normal light image processing unit 62 and the special light image processing unit 64 is referred to as an image signal, and a digital image signal after image processing is referred to as image data. To

The normal light image processing unit 62 includes a color conversion unit 68, a color emphasizing unit 70, and a structure emphasizing unit 72. The color converter 68 allocates the input B, G, and R image signals for one frame to R image data, G image data, and B image data, respectively. These RGB image data are further subjected to color conversion processing such as 3 × 3 matrix processing, tone conversion processing, three-dimensional LUT processing, etc., and converted to color converted RGB image data.

The color emphasizing unit 70 performs various color emphasizing processing on the color converted RGB image data. The structure emphasizing unit 72 performs structure emphasizing processing such as spatial frequency emphasizing on the color emphasizing processed RGB image data. The RGB image data subjected to the structure emphasizing process by the structure emphasizing unit 72 is input from the normal light image processing unit 62 to the image display signal generating unit 66 as a normal light image.

The special light image processing unit 64 generates an oxygen saturation image based on the input two frames of B1 and R1 image signals and G2 and R2 image signals, and an oxygen saturation image generation unit 76. And a structure emphasizing unit 78 that performs structure emphasizing processing such as spatial frequency emphasizing. The RGB image data subjected to the structure emphasis processing by the structure emphasis unit 78 is input from the special light image processing unit 64 to the image display signal generation unit 66 as a special light image.

The image display signal generation unit 66 converts the normal light image or the special light image input from the normal light image processing unit 62 or the special light image processing unit 64 into a display image signal for displaying as a displayable image on the monitor 18. Do. The monitor 18 displays a normal light image or a special light image based on the converted display image signal. As a special light image, an oxygen saturation image of one frame is displayed from RGB image signals of two frames.

As shown in FIG. 8, the oxygen saturation image generation unit 76 includes a signal correction unit 80, a measurement signal ratio calculation unit 81, a correlation storage unit 82, and an oxygen saturation calculation unit (biological function information calculation unit). 83 and an image generation unit 84. The signal correction unit 80 includes a search condition setting unit 80 a, a position alignment unit 80 b, a reference signal ratio calculation unit (reference information calculation unit) 80 c, and a correction unit 80 d. The image signal, the G2 image signal, and the R2 image signal are corrected to be equivalent to the image signal obtained under the reference inter-frame intensity ratio.

In the signal correction unit 80, first, the search condition setting unit 80a sets various conditions (search conditions) of the search point used for alignment processing in the first and second alignment units 80b and 80c. After setting the search conditions, as shown in FIG. 9, the first alignment unit 80b calculates the amount of displacement of the sample between the B1 image signal and the G2 image signal, and the sample between the B1 image signal and the G2 image signal Align the image. In the first alignment unit 80b, the B1 image signal after alignment is set as a “B1a image signal” in order to deform the B1 image signal and align it with the G2 image signal.

Then, the second alignment unit 80c aligns the sample image between the R1 image signal and the R2 image signal based on the positional shift amount calculated by the first alignment unit 80b. Then, the reference signal ratio calculation unit 80d calculates the reference signal ratio used to correct the G2 image signal and the R2 image signal from the aligned R1 image signal and the R2 image signal. Finally, based on the reference signal ratio, the correction unit 80e corrects the G2 image signal and the R2 image signal to be equal to the image signal obtained under the reference inter-frame intensity ratio. Thereby, the G2a image signal and the R2a image signal are obtained. The B1a image signal, the G2a image signal, and the R2a image signal obtained by the above-described series of processes are used to calculate the oxygen saturation.

The search condition setting unit 80a performs, as a search condition, position setting of a reference point, position setting of a search point, and setting of a search range. As shown in FIG. 10A, reference points P1 to P9 are provided at predetermined positions of nine areas A1 to A9 (3 × 3) in the B1 image signal. The search points D1 to D9 are provided at the same pixel positions as the reference points P1 to P9 in nine areas A1 to A9 (3 × 3) in the G2 image signal, as shown in FIG. 10B. These search points D1 to D9 are translated (searched) in the X direction or the Y direction within a predetermined search range within nine areas A1 to A9 in the G2 image signal. By searching for the search points D1 to D9, a pixel or pixel area (target point T) having a feature quantity (for example, pixel value or pixel value distribution) closest to the reference points P1 to P9 is detected. The reference points P1 to P9 may be set in the G2 image signal, and the search points D1 to D9 may be set in the B1 image signal.

The reference points P1 to P9 and the search points D1 to D9 are set at the centers of the areas A1 to A9 when the brightness of the areas A1 to A9 is almost the same as shown in FIG. 11A. As described above, in the case where the brightnesses of the respective areas A1 to A9 are substantially the same, for example, as shown in FIG. 11B, in the lumen, a protuberance or the like in front of the distal end portion 24 of the endoscope 12 It is possible that there is no case.

On the other hand, as shown in FIG. 12A, when there is a dark area (“area A5” in FIG. 12A) in which the dark part BP where the pixel value is equal to or less than the fixed value is present in areas A1 to A9. A reference point P5 and a search point D5 are set in a part other than the dark part BP in the dark area. This is because when the reference point P5 and the search point D5 are set in the dark part BP, the target point T is detected immediately after the search, so that the alignment can not be accurately performed. As shown in FIG. 12B, for example, as shown in FIG. 12B, it may be considered that a protrusion 86 appears in front of the distal end portion 24 of the endoscope 12 in the lumen as a case where the partial area becomes dark. In addition, the brightness of each area is calculated | required from the average value of the pixel value of each area. In addition, it is not necessary to set the reference point and the search point for an area where there are few landmarks required for alignment such as blood vessel structure.

Regarding the search range, in the case of no movement state where there is little movement of the tip part 24 of the endoscope 12 and the specimen, as shown in FIG. 13, the first search with the movement range of the search points D1 to D9 narrowed. Set to range X. This is because in the case of no movement, detection of the target point T is possible without searching far. On the other hand, when the distal end portion 24 of the endoscope 12 is largely bent or when the specimen has a large movement such as when there is a large movement, as shown in FIG. The range of the search points D1 to D9 is set to a second search range Y which is broadened. This is because it is difficult to detect the target point T without searching far in the case of the motion presence state.

The following method can be considered as a method of determining which of the non-motion state or the motion state. For example, when the zooming lens 47 is not operated as in screening, it is considered that there is movement in the specimen because the frequency of moving the tip 24 of the endoscope 12 is large. Therefore, when the zooming lens 47 is not in operation, it is determined that there is a movement. On the other hand, when operating the zooming lens 47 as in the case of magnified observation, it is considered that the frequency of movement of the distal end portion 24 of the endoscope 12 in a substantially stationary state is low. Conceivable. Therefore, when the zooming lens 47 is operated, it is determined that there is no movement. Further, the mode switching switch 22b may switch between the non-motion state and the motion state.

When the distance between the tip of the endoscope 12 and the sample is less than a certain value, as in the case of the magnified observation, while searching is performed in the first search range X having a narrow search range, When the inter-specimen distance is equal to or more than a predetermined value, it is preferable to conduct the search in the second search range Y where the search range is wide. The inter-specimen distance is preferably determined based on the exposure amount of the image sensor 48. That is, when the exposure amount is small, the inter-specimen distance is far, and when the exposure amount is large, the inter-specimen distance is close.

The first alignment unit 80 b includes a high frequency filtering unit (high frequency component extraction unit) HF that performs high frequency frequency filtering processing on the B1 image signal and the G2 image signal. Information of high frequency components such as landmarks (for example, blood vessel structure) serving as landmarks at the time of alignment is sharply extracted from the B1 image signal and G2 image signal in high frequency frequency filtering processing, so the target by the search points D1 to D9 The point T can be detected with high accuracy.

Then, the first alignment unit 80b sets nine reference points P1 to P9 in the B1 image signal and sets nine search points D1 to D9 in the G2 image signal in accordance with the set search condition. Then, each search point D1 to D9 is searched within a predetermined search range. Then, the movement amount of the search points D1 to D9 when the search points D1 to D9 detect the target point T is calculated for each area. The amount of movement of the search points D1 to D9 in each of these areas is the amount of positional deviation of the specimen image in each area of the B1 image signal and the G2 image signal. The first alignment unit 80b may normalize the B1 image signal and the G2 image signal with predetermined image signals, convert the normalized signals into pyramid images, and then calculate the amount of positional deviation.

Then, based on the positional deviation amount for each area, the pixel value of each pixel of the B1 image signal is interpolated to deform the specimen image. By this deformation process, the position of the sample image of the B1 image signal is aligned with the position of the sample image of the G2 image signal. Thereby, the alignment between the G2 image signals of the B1 image signal is completed. Here, the B1 image signal after alignment is taken as a B1a image signal. In addition, when the movement amount of the search point in the predetermined area deviates largely from the movement amount of the search point in the other area, the movement amount of the search point in the predetermined area is the movement of the search point in the other area It is preferable to make corrections based on the amount. The sample image of the G2 image signal may be aligned with the position of the sample image of the B1 image signal by interpolating the pixel value of each pixel of the G2 image signal to deform the sample image.

The second alignment unit 80c includes a low frequency filtering unit (low frequency component extraction unit) LF that performs low frequency frequency filtering on the R1 image signal and the R2 image signal. The high frequency components of the R1 image signal and the R2 image signal after low-frequency frequency filtering are image signals that contain a lot of brightness information. For each area of R1 image signal and R2 image signal, the pixel value of the pixel of each area is interpolated based on the positional deviation amount for each area calculated by the first alignment unit 80b, and the specimen image is deformed. . Thereby, the alignment between the R1 image signal and the R2 image signal is completed.

Here, the position shift amount between the B1 image signal and the G2 image signal is used for alignment between the R1 image signal and the R2 image signal for the following reason. The R1 image signal and the R2 image signal have many red wavelength components that have a low absorption coefficient of the mucous membrane absorber (hemoglobin), so they contain much information on the amount of light, but they can be alignment landmarks There are not many images of structures. Therefore, for the R1 image signal and the R2 image signal, it is difficult for the search point D to detect the target point T, so the movement amount of the search point D, that is, the positional shift amount can not be accurately calculated in many cases.

On the other hand, B1 image signal and G2 image signal have many blue wavelength components with high absorption coefficient of the absorber (hemoglobin) of mucous membrane, so there are many images of structures that can be land marks such as blood vessel structure. include. Therefore, for the B1 image signal and the G2 image signal, the detection of the target point T by the search point D is easy, so the movement amount of the search point D, that is, the positional shift amount can be accurately obtained. Therefore, for positional alignment between the R1 image signal and the R2 image signal, not the positional displacement amount of the R1 image signal and the R2 image signal but the positional displacement amount between the B1 image signal and the G2 image signal is used.

The reference signal ratio calculation unit 80d calculates a reference signal ratio C indicating the ratio (R2 / R1) between the aligned R1 image signal and the R2 image signal for each pixel. The reference signal ratio C increases or decreases in conjunction with the actual inter-frame intensity ratio (I2 (λ) / I1 (λ)) for the following three reasons (1) to (3).
(1): The first fluorescence and the second fluorescence have the same waveform, and the inter-frame intensity ratio (I2 (λ) / I1 (λ)) of the first fluorescence and the second fluorescence is at any wavelength. It is identical (see FIG. 5).
(2): The R pixel of the image sensor 48 is sensitive only to the long wavelength side of the first and second fluorescence (see FIG. 6)
(3): From (1) and (2), the R1 image signal and the R2 image signal both have almost the same information on the living tissue to be the subject.

From the above, the reference signal ratio C almost accurately represents the actual inter-frame intensity ratio. Here, since the R1 image signal and the R2 image signal used for calculation of the reference signal ratio C are accurately aligned, even if there is a region with different brightness in the image, it will be in each pixel The reference signal ratio C accurately indicates the actual inter-frame intensity ratio. The reference signal ratio under the condition that the light amount control by the light source control unit 40 is ideally operated is stored in advance in a memory (not shown) as the reference signal ratio “Ca”.

The correction unit 80e corrects the G2 image signal and the R2 image signal using the reference signal ratio C and the reference signal ratio Ca calculated by the reference signal ratio calculation unit 80d. The G2 image signal and the R2 image signal are corrected based on the following equations to become the G2a image signal and the R2a image signal. The correction is performed for each pixel of the G2 image signal and the R2 image signal.
R2a = R2 / C × Ca
G2a = G2 / C × Ca
In this equation, "R2" and "G2" indicate "R2 image signal" and "G2 image signal" before correction, "R2a" and "G2a" indicate "G2a image signal" after correction, "R2a image signal" is shown. The G2a image signal and the R2a image signal are corrected to be equal to the image signal obtained under the reference interframe intensity ratio. That is, when the light source control (AE) in the light source control unit 40 is ideally operated, the reference signal ratio C matches the reference signal ratio Ca, so the G2 image signal before correction and after correction And R2 image signal values are almost the same.

On the other hand, when AE is destabilized, the actual inter-frame intensity ratio may deviate from the reference inter-frame intensity ratio. For example, when the actual inter-frame intensity ratio becomes larger than the reference inter-frame intensity ratio (ie, in the case of reference signal ratio C> reference reference signal ratio Ca), G2 is canceled so as to cancel this increase. Reduce the pixel values of the image signal and the R2 image signal. On the contrary, when the actual inter-frame intensity ratio becomes smaller than the reference inter-frame intensity ratio (that is, in the case of reference signal ratio C <reference signal ratio Ca), this reduction is canceled out. The pixel values of the G2 image signal and the R2 image signal are increased. As a result, even if the AE becomes unstable and the actual inter-frame intensity ratio changes from the reference inter-frame intensity ratio, the AE operates ideally by correcting the image signal so as to cancel out this fluctuation. It is possible to obtain the same image signal as when

In addition, since the reference signal ratio C that accurately represents the inter-frame intensity ratio of each pixel is used for correction of the G2 image signal and the R2 image signal, there is temporarily an area having different brightness in the image. Also, appropriate brightness correction is performed in each area. That is, for bright areas in the image, correction is performed to reduce the brightness by reducing the pixel values of the G2 image signal and the R2 image signal, and for dark areas in the image, the G2 image signal and the R2 image By increasing the pixel value of the signal, correction is made to increase the brightness.

The measurement signal ratio calculation unit 81 sets the measurement signal ratio B1 / G2 between the B1a image signal and the G2a image signal and the measurement signal ratio R2 / G2 between the G2a image signals G2 and R2a image signal for each pixel. Ask. Here, “B1a image signal, G2a image signal, R2a image signal” used for calculation of the measurement signal ratios B1 / G2 and R2 / G2 are corrected by the signal correction processing in the signal correction unit 80, and therefore The oxygen saturation can be accurately calculated by the measurement signal ratios B1 / G2 and R2 / G2.

The correlation storage unit 82 stores the correlation between the measurement signal ratios B1 / G2 and R2 / G2 and the oxygen saturation. This correlation is stored as a two-dimensional table in which isolines of oxygen saturation are defined in the two-dimensional space shown in FIG. The position and shape of this contour line are obtained by physical simulation of light scattering, and are defined to change according to blood volume. For example, when there is a change in blood volume, intervals between contour lines become wide or narrow. The measurement signal ratios B1 / G2 and R2 / G2 are stored in log scale.

The above correlation is closely related to the light absorption characteristics and the light scattering characteristics of oxygenated hemoglobin and reduced hemoglobin as shown in FIG. In FIG. 16, a graph 90 shows the absorption coefficient of oxygenated hemoglobin and a graph 91 shows the absorption coefficient of reduced hemoglobin. For example, at a wavelength with a large difference in absorption coefficient, such as the central wavelength 473 nm of the first blue laser light, it is easy to obtain information on oxygen saturation. However, a B1a image signal including a signal corresponding to 473 nm light is highly dependent not only on oxygen saturation but also on blood volume. Therefore, in addition to the B1a image signal, the measurement signal ratio B1 / obtained from the R2a image signal corresponding to the light that changes mainly depending on the blood volume, and the G2a image signal serving as the reference signal of the B1a image signal and the R2a image signal By using G2 and R2 / G2, oxygen saturation can be accurately determined without depending on blood volume.

The oxygen saturation calculation unit 83 refers to the correlation stored in the correlation storage unit 82, and the oxygen saturation corresponding to the measurement signal ratios B1 / G2 and R2 / G2 determined by the measurement signal ratio calculation unit 81. Find the degree. The oxygen saturation is calculated for each pixel. The oxygen saturation calculation unit 83 calculates the oxygen saturation as follows. For example, when the measurement signal ratio at a predetermined pixel is B1 ^* / G2 ^* and R2 ^* / G2 ^* , referring to the correlation as shown in FIG. 17, the measurement signal ratio B1 ^* / G2 ^* , The oxygen saturation corresponding to R2 ^* / G2 ^* is "60%". Therefore, the oxygen saturation is calculated as “60%”.

The measurement signal ratios B1 / G2 and R2 / G2 are calculated based on the B1 image signal and the G2a image signal and the R2a image signal corrected by the signal correction unit 80. The ratios B1 / G2 and R2 / G2 hardly increase or decrease very little. That is, the measurement signal ratios B1 / G2 and R2 / G2 are higher than the lower limit line 93 of 0% of oxygen saturation or lower than the upper limit line 94 of 100% of oxygen saturation in correlation. There is almost nothing.

However, if the measurement signal ratios B1 / G2 and R2 / G2 are positioned above the lower limit line 93 in correlation, the oxygen saturation is 0%, and the measurement signal ratios B1 / G2 and R2 / G2 are When positioned below the upper limit line 94, the oxygen saturation is set to 100%. If the corresponding point is out of the range between the lower limit line 93 and the upper limit line 94, the reliability of the oxygen saturation in the pixel may be lowered and not displayed.

The image generation unit 84 generates an oxygen saturation image in which the oxygen saturation is imaged, using the oxygen saturation calculated by the oxygen saturation calculation unit 83, and the B2 image signal, the G2 image signal, and the R2 image signal. . The image generation unit 84 applies a gain according to the oxygen saturation to the B2 image signal, the G2 image signal, and the R2 image signal. For example, when the oxygen saturation is 60% or more, the same gain "1" is applied to all of the B2 image signal, the G2 image signal, and the R2 image signal. On the other hand, when the oxygen saturation is less than 60%, a gain less than "1" is applied to the B2 image signal, while "1" is applied to the G2 image signal and the R2 image signal. More gain is applied. The B2 image signal, the G2 image signal, and the R2 image signal after the gain processing are allocated to the BGR image data.

The oxygen saturation image displayed on the monitor 18 on the basis of these BGR image data is a B2 image signal with a gain of “1” and a G2 in the high oxygen region (region where the oxygen saturation is 60 to 100%). Since the pixel values of the image signal and the R2 image signal do not change, they are displayed in the same color as the normal light image. On the other hand, in the low oxygen region where the oxygen saturation is below a certain value (the region where the oxygen saturation is 0 to 60%), the gain is less than "1" or exceeds "1" according to the oxygen saturation. Is displayed in a color different from the light image, that is, a pseudo color. In the image generation unit, only the low oxygen area is displayed in pseudo color, but not only the low oxygen area but also the high oxygen area (60 to 100%) may be displayed in pseudo color.

Next, a series of flows in the present embodiment will be described along the flowchart of FIG. First, in the normal observation mode, screening is performed from the distant view state. In the normal observation mode, a normal light image is displayed on the monitor 18. At the time of this screening, when a site having a possibility of a lesion such as a brownish area or redness (lesion likely site) is detected, the mode switching SW 22b is operated to switch to the special observation mode. In this special observation mode, it is diagnosed whether or not the lesion-prone site is in hypoxia.

In the special observation mode, the first and second white lights are alternately emitted. Then, the image sensor 48 picks up an image of the sample illuminated by the first white light, whereby the image sensor 48 outputs the B1 image signal, the G1 image signal, and the R1 image signal, and the sample illuminated by the second white light By capturing an image with the image sensor 48, the image sensor 48 outputs a B2 image signal, a G2 image signal, and an R2 image signal. These two frames of image signals are used to create one frame of oxygen saturation image.

Next, for each of the areas A1 to A9 in the B2 image signal and the G2 image signal, based on the exposure amount when acquiring the image signal for two frames of alignment, the operating condition of the zooming lens, the movement amount of the specimen, etc. The reference points P1 to P9 and the search points D1 to D9 are set, and the search range of the search points D1 to D9 is set. Then, in each of the areas A1 to A9, the search points D1 to D9 are searched within the set search range. Then, the amount of movement when the search points D1 to D9 detect the target point T is taken as the amount of positional deviation between frames. The alignment between the B1 image signal and the G2 image signal is performed based on the positional deviation amount between the frames.

Next, based on the positional deviation amount between the B1 image signal and the G2 image signal, alignment between the R1 image signal and the R2 image signal is performed. Then, a reference signal ratio C is calculated based on the aligned R1 image signal and R2 image signal. Then, the G2 image signal and the R2 image signal are corrected using the reference signal ratio C and the reference signal ratio Ca. As a result, G2a image signal and R2a image signal which are image signals similar to those when AE is ideally operated can be obtained. Then, based on the aligned B1a image signal, the G2a image signal, and the R2a image signal, the oxygen saturation is calculated. An oxygen saturation image is generated based on the calculated oxygen saturation, the B2 image signal, the G2 image signal, and the R2 image signal.

The generated oxygen saturation image is displayed on the monitor 18 as a special light image. Based on the oxygen saturation image displayed on the monitor 18, the doctor confirms whether or not the lesion site is hypoxic. The display of the oxygen saturation is continuously displayed until the normal observation mode is switched. Then, when the diagnosis is finished, the insertion portion 21 of the endoscope 12 is extracted from the inside of the sample.

In the first embodiment, the phosphor 44 is provided at the distal end portion 24 of the endoscope 12. However, instead of this, as shown in the endoscope system 100 of FIG. A phosphor 44 may be provided. In this case, the phosphor 44 is provided between the first blue laser light source (473 LD) 34 and the second blue laser light source (445 LD) 36 and the light guide 41. The first blue laser light source 34 or the second blue laser light source 36 irradiates the phosphor 44 with the first blue laser light or the second blue laser light. Thereby, the first white light or the second white light is emitted. The first or second white light is irradiated into the sample through the light guide 41. Except for this, the endoscope system 100 is similar to the endoscope system 10.

In the first embodiment, the first and second blue laser beams are incident on the same phosphor 44. However, the first blue laser beam and the second blue laser beam may be respectively separated into the first phosphor and the second phosphor. (2) The light may be incident on the phosphor. In this case, of the fluorescence emitted from the first phosphor, the light of the first red component incident on the R pixel of the image sensor 48 and the fluorescence emitted from the second phosphor enter the R pixel of the image sensor 48 It is necessary to make the same waveform for the second red component light. In addition, it is necessary to make the intensity ratio of the light of the first red component and the light of the second red component constant regardless of the wavelength. This is to interlock the reference signal ratio C with the increase and decrease of the actual inter-frame intensity ratio.

Second Embodiment
As shown in FIG. 20, in the light source device 14 of the endoscope system 200, instead of the first and second blue laser light sources 34 and 36 and the light source controller 40, an LED light source unit 202 and an LED light source controller A light source control unit 204 is provided. In addition, the fluorescent body 44 is not provided in the illumination optical system 24 a of the endoscope 200. Other than that, it is the same as that of endoscope system 10 of a 1st embodiment.

The LED light source unit 202 has four LEDs as light sources that emit light limited to a specific wavelength range. Specifically, the LED light source unit 202 includes an LED (B) that emits blue band light B (hereinafter referred to simply as blue light) in the blue region of 400 to 500 nm, and a blue narrow band light limited to 473 nm ± 10 nm. An LED (473) that emits Nb, an LED (G) that emits green band light G (hereinafter simply referred to as green light) in the green range of 480 to 620 nm, red band light R in the red range of 600 to 720 nm Hereinafter, it has LED (R) which light-emits only red light. The LED light source unit 202 may be provided with a plurality of LEDs that emit narrow band light with slightly different wavelength ranges so that each LED emits light in a broad wavelength range.

In the present invention, the “first signal light” corresponds to the “blue narrowband light Nb”, and the “first reference light” corresponds to the “red light R”. Therefore, the "first light source" of the present invention includes the LED (473) and the LED (R). In the present invention, the "second signal light" corresponds to the "green light G", and the "second reference light" corresponds to the "red light R". Therefore, the "second light source" of the present invention includes the LED (G) and the LED (R).

The LED light source control unit 204 controls each of the LEDs of the LED light source unit 202 individually. Further, the LED light source control unit 204 drives the LEDs (B), (G) and (R) in the normal observation mode. On the other hand, in the case of the special observation mode, in a state in which the LEDs (G) and (R) are always lit, the LED (473) and the LED (B) are controlled to be alternately lit. .

The imaging control unit 49 performs the following imaging control for each observation mode. As shown in FIG. 21A, in the normal observation mode, the color image sensor 48 captures an image of the inside of the subject simultaneously illuminated with blue light B, green light G and red light R every period of one frame, ie, blue light A step of accumulating charges obtained by photoelectric conversion of B, green light G and red light R, and a step of reading out the accumulated charges as a B image signal, a G image signal, and an R image signal are performed. Such an operation is repeatedly performed while the normal observation mode is set. Then, based on the image signals for one frame, a normal light image is generated by the same method as the first embodiment.

On the other hand, as shown in FIG. 21B, in the special observation mode, in the first frame, a step of accumulating charges obtained by photoelectric conversion of blue narrowband light Nb, green light G, and red light R; Reading out as the B1 image signal, the G1 image signal, and the R1 image signal, and storing the charge obtained by photoelectrically converting the blue light B, the green light G and the red light R in the next second frame; The step of reading out the accumulated charges as the B2 image signal, the G2 image signal, and the R2 image signal is performed. Such operation is repeated while being set in the special observation mode. Then, based on the image signals for these two frames, an oxygen saturation image is generated in the same manner as in the first embodiment.

Here, since the red light R of the first frame and the red light R of the second frame emit light from the same LED (R), their respective waveforms are the same, and their intensity ratio is the wavelength It is the same regardless. Therefore, the reference signal ratio C indicating the ratio between the R1 image signal obtained at the first frame red light emission and the R2 image signal obtained at the second frame red light emission interlocks with the actual inter-frame intensity ratio. Increase or decrease. Therefore, also in the second embodiment, the reference signal ratio C accurately represents the actual inter-frame intensity ratio.

In the second embodiment, in the special observation mode, the red light R in the first frame and the red light R in the second frame emit light from the same LED (R), but emit light from separate LEDs (R). May be However, in this case, the first red light emitted from the first LED (R) in the first frame and the second red light emitted from the second LED (R) in the second frame have the same spectrum. The intensity ratio at each wavelength needs to be the same. This is to interlock the reference signal ratio C with the increase and decrease of the actual inter-frame intensity ratio.

Third Embodiment
As shown in FIG. 22, in the light source device 14 of the endoscope system 300, instead of the first and second blue laser light sources 34 and 36, and the light source control unit 40, a broadband light source 302, a rotation filter 304, and a filter switching unit 305 is provided. Other than that, it is the same as that of endoscope system 10 of a 1st embodiment.

The broadband light source 302 is a xenon lamp, a white LED, or the like, and emits white light in a wavelength range ranging from blue to red. The rotation filter 304 rotates around the rotation axis 304a, and includes a normal observation mode filter 308 provided inside and a special observation mode filter 309 provided outside (see FIG. 23). . The filter switching unit 305 moves the rotary filter 304 in the radial direction, and inserts the normal observation mode filter 308 of the rotary filter 304 into the optical path of the white light when the mode switching switch 22 b is set to the normal observation mode. When the special observation mode is set, the special observation mode filter 309 of the rotary filter 304 is inserted into the light path of the white light. The rotating shaft 304a is supported by two support rods 304b.

As shown in FIG. 23, the normal observation mode filter 308 is provided with an opening 308 a that transmits white light as it is. Therefore, in the normal observation mode, white light is irradiated into the sample. In the special observation mode filter 309, a band pass filter (BPF) 309a for transmitting band-limited light (473, GR) of a predetermined band of white light along the circumferential direction, and an opening for transmitting the white light as it is 309b is provided. Therefore, in the special observation mode, the band-limited light (473, GR) and the white light are alternately irradiated into the sample by rotating the rotary filter 304. In the third embodiment, the rotation filter 304 and a drive unit (not shown) that controls the rotation speed of the rotation filter 304 constitute the “light source control unit” of the present invention.

As shown in FIG. 24, the band pass filter 309a has transparency at 473 nm ± 10 nm and 500 to 700 nm (green region to red region), and blocks the other wavelengths. Therefore, the band-limited light (473, GR) has wavelengths of 473 nm ± 10 nm and 500 to 700 nm.

In the present invention, the “first signal light” corresponds to “the light which enters the B pixel of the image sensor 48 in the band-limited light”, and the “first reference light” corresponds to the “image sensor 48 in the band-limited light”. Light corresponding to the R pixel of Therefore, the "first light source" of the present invention includes the broadband light source 302 and the band pass filter 309a. Further, in the present invention, the “second signal light” corresponds to “the light which is incident on the G pixel of the image sensor 48 in the white light”, and the “second reference light” corresponds to the “R” of the image sensor 48 in the white light. Corresponds to the light incident on the pixel. Thus, the “second light source” of the present invention will have a broadband light source 302.

The imaging control unit 49 performs the following imaging control for each observation mode. As shown in FIG. 25A, in the normal observation mode, a step of accumulating charges obtained by photoelectric conversion of white light every period of one frame, and the accumulated charges in B image signal, G image signal, R image signal The step of reading out is performed. Such an operation is repeatedly performed while the normal observation mode is set. Then, based on the image signals for one frame, a normal light image is generated by the same method as the first embodiment.

On the other hand, as shown in FIG. 25B, in the special observation mode, in the first frame, a step of accumulating charges obtained by photoelectric conversion of band-limited light (473, GR), accumulated charges B1 image signal, G1 A step of reading out as an image signal and an R1 image signal is performed, and in the next second frame, a step of accumulating a charge obtained by photoelectric conversion of white light, and a stored charge is a B2 image signal, a G2 image signal, R2 A step of reading out as an image signal is performed. Such operation is repeated while being set in the special observation mode. Then, based on the image signals for these two frames, an oxygen saturation image is generated in the same manner as in the first embodiment.

Here, the red light component received by the R pixel of the image sensor in the band-limited light of the first frame and the red light component received by the R pixel of the white light of the second frame are emitted from the same broadband light source 302 Therefore, the respective waveforms are the same, and their intensity ratios are the same regardless of the wavelength. Therefore, the reference signal ratio C indicating the ratio between the R1 image signal obtained at the time of band-limited light emission of the first frame and the R2 image signal obtained at the time of white light emission of the second frame interlocks with the actual inter-frame intensity ratio. To increase or decrease. Therefore, also in the third embodiment, the reference signal ratio C represents the inter-frame intensity ratio.

Fourth Embodiment
In the third embodiment, an example of the endoscope system 300 provided with the broadband light source 302, the rotation filter 304, and the filter switching unit 305 has been described, but as shown in FIG. 26, the endoscope system of the fourth embodiment The rotary filter 404, the semiconductor light source LD (473) 406, the semiconductor light source control unit 408, and the light merging unit 410 may be provided in 400. Other than that, it is the same as that of endoscope system 300 of a 3rd embodiment.

As shown in FIG. 27, the rotation filter 404 rotates around the rotation axis 404a, and includes a normal observation mode filter 412 provided inside and a special observation mode filter 413 provided outside. ing. The normal observation mode filter 412 is provided with an opening 412 a that transmits white light as it is. Therefore, in the normal observation mode, white light is irradiated into the sample. The rotating shaft 404a is supported by two support rods 404b.

The filter for special observation mode 413 includes a band pass filter (BPF) 413a for transmitting band-limited light (GR) of a predetermined band of white light and an opening 413b for transmitting white light as it is along the circumferential direction. It is provided. Therefore, in the special observation mode, the band-limited light (GR) and the white light are alternately irradiated into the sample by rotating the rotary filter 404. As shown in FIG. 28, the band pass filter 413a is transparent in the wavelength range of 500 to 700 nm, and blocks the other wavelengths. Thus, the band limited light (GR) has a wavelength of 500 to 700 nm.

The semiconductor light source LD (473) 406 emits blue narrow band light Nb of 473 nm ± 10 nm. The semiconductor light source control unit 408 acquires a detection signal from an image sensor (not shown) that detects the rotation of the rotation filter 404, and according to the acquired detection signal, the driving timing and synchronization timing of the semiconductor light source LD (473) 406, Control such as lighting and extinguishing. Thus, the semiconductor light source control unit 408 does not emit the blue narrow band light Nb within the irradiation period in which the white light is irradiated into the sample, and within the irradiation period in which the band limited light (GR) is irradiated into the sample. Emits blue narrow band light Nb. In the fourth embodiment, the rotation filter 404, a drive unit (not shown) for controlling the rotation speed of the rotation filter 404, and the semiconductor light source control unit 408 constitute the “light source control unit” of the present invention. .

The light merging portion 410 is formed of a dichroic mirror, transmits the light from the rotation filter 404 to be incident on the LG 41, reflects the light from the blue semiconductor light source LD (473) 406, and causes the light to be incident on the LG 41.

In the present invention, the “first signal light” corresponds to the “blue narrowband light Nb”, and the “first reference light” corresponds to the “light that enters the R pixel of the image sensor 48 in the band-limited light”. Do. Therefore, the “first light source” of the present invention includes the broadband light source 302, the semiconductor light source LD (473) 406, and the band pass filter (BPF) 413a. Further, in the present invention, the “second signal light” corresponds to “the light which is incident on the G pixel of the image sensor 48 in the white light”, and the “second reference light” corresponds to the “R” of the image sensor 48 in the white light. Corresponds to the light incident on the pixel. Thus, the “second light source” of the present invention will have a broadband light source 302.

As shown in FIG. 29A, in the normal observation mode, a step of accumulating charges obtained by photoelectric conversion of white light every period of one frame, and the accumulated charges in B image signal, G image signal, R image signal The step of reading out is performed. Such an operation is repeatedly performed while the normal observation mode is set. Then, based on the image signals for one frame, a normal light image is generated by the same method as the first embodiment.

On the other hand, as shown in FIG. 29B, in the special observation mode, the step of accumulating the charge obtained by photoelectrically converting the blue narrowband light Nb and the band limited light (GR) in the first frame; A step of reading out as an image signal, a G1 image signal, and an R1 image signal is performed, and in the next second frame, a step of accumulating a charge obtained by photoelectric conversion of white light; A step of reading as an image signal and an R2 image signal is performed. Such operation is repeated while being set in the special observation mode. Then, based on the image signals for these two frames, an oxygen saturation image is generated in the same manner as in the first embodiment.

Here, the red light component received by the R pixel of the image sensor in the band-limited light of the first frame and the red light component received by the R pixel of the white light of the second frame are emitted from the same broadband light source 302 Therefore, the respective waveforms are the same, and their intensity ratios are the same regardless of the wavelength. Therefore, the reference signal ratio C indicating the ratio between the R1 image signal obtained at the time of band-limited light emission of the first frame and the R2 image signal obtained at the time of white light emission of the second frame interlocks with the actual inter-frame intensity ratio. To increase or decrease. Therefore, also in the fourth embodiment, the reference signal ratio C accurately represents the inter-frame intensity ratio.

Although the oxygen saturation is generated from the two measurement signal ratios B1 / G2 and R2 / G2 in the above embodiment, the oxygen saturation may be calculated only from the measurement signal ratio B1 / G2. In this case, the correlation storage unit storing the correlation between the measurement signal ratio B1 / G2 and the oxygen saturation is used to calculate the oxygen saturation.

In the above-described embodiment, the imaging of the oxygen saturation degree is performed. However, in addition to this, the imaging of the blood volume may be performed. The blood volume has a correlation with the measurement signal ratio R2 / G2 obtained by the measurement signal ratio calculation unit. Therefore, by assigning different colors according to the measurement signal ratio R2 / G2, it is possible to create a blood volume image in which the blood volume is imaged.

In the above embodiment, the oxygen saturation, which is the ratio of oxygenated hemoglobin in the blood volume (sum of oxygenated hemoglobin and reduced hemoglobin), is calculated, but instead of or in addition to this, “blood volume × oxygen saturation Other biological function information such as an oxygenated hemoglobin index obtained from (%) or a reduced hemoglobin index obtained from “blood volume × (100−oxygen saturation) (%)” may be calculated.

Claims (13)

A first light source that emits a first illumination light including a first signal light and a first reference light;
A second light source for emitting a second illumination light including a second signal light having a wavelength range different from that of the first signal light and a second reference light;
A light source control unit configured to control an irradiation timing of the first illumination light and the second illumination light such that the first illumination light and the second illumination light are alternately irradiated to the specimen;
During illumination of the specimen by the first illumination light, the first signal light is captured by wavelength-dividing the reflected light of the first illumination light into the first signal light and the first reference light. And outputting a first reference image signal corresponding to the first reference light, and during illumination of the sample by the second illumination light, A second signal image signal corresponding to the second signal light is output by wavelength-dividing the reflected light of the illumination light into the second signal light and the second reference light, and the second reference light is output. An imaging unit that outputs a second reference image signal corresponding to light;
A first alignment unit that calculates an amount of positional deviation between the first signal image signal and the second signal image signal, and performs alignment between the signal image signals;
A second alignment unit that aligns the first reference image signal and the second reference image signal based on the positional shift amount;
A reference information calculation unit that calculates reference information on the intensity of the first and second signal light for each pixel based on the first reference image signal and the second reference image signal that have been aligned;
A correction unit that corrects the first signal image signal or the second signal image signal based on the reference information;
A biological function information calculation unit which calculates biological function information based on the first signal image signal or the second signal image signal after correction;
An endoscope system comprising: A high frequency component extraction unit for performing high frequency filtering for extracting high frequency components on the first signal image signal and the second signal image signal;
The first alignment unit performs the calculation of the positional deviation amount and the alignment based on the first signal image signal and the second signal image signal after the high frequency filtering. The endoscope system according to claim 1. The low-frequency component extraction unit performs low-frequency filtering to extract low-frequency components on the first reference image signal and the second reference image signal that have been aligned.
3. The endoscope according to claim 1, wherein the second alignment unit aligns the first reference image signal and the second reference image signal after the low frequency filtering. Mirror system. Reference points are respectively set in a plurality of areas of one of the first signal image signal and the second signal image signal, and search is made at a position corresponding to the reference point in the other image signal. It has a search condition setting unit to set points,
The first alignment unit performs a detection process of detecting a target point having a feature amount closest to the reference point by moving the search point within a predetermined search range,
The endoscope system according to claim 1, wherein the positional deviation amount is a movement amount of the search point when the target point is detected. The endoscope system according to claim 4, wherein the reference point and the search point are set in a part other than the dark part in the dark area for the dark area in which the dark part is present among the plurality of areas. The endoscope system according to claim 4 or 5, wherein a search range when the distance to the sample is a predetermined value or more is made wider than a search range when the distance is less than a predetermined value. A sample enlargement unit for enlarging the sample;
The endoscope system according to claim 4 or 5, wherein a search range when the sample enlargement unit is not used is made wider than a search range when the sample enlargement unit is used. The imaging unit receives a plurality of first pixels that receives the first signal light and outputs the first signal image signal, and receives the second signal light and outputs the second signal image signal. A color image provided with a plurality of second pixels and a plurality of third pixels that receive the first or second reference light and output the first reference image signal or the second reference image signal The endoscope system according to claim 1, wherein the endoscope system is a sensor. The endoscope system according to claim 1, wherein the first and second signal lights have a wavelength range shorter than that of the first and second reference lights. The first reference light and the second reference light have the same waveform, and the intensity ratio of the first reference light and the second reference light is the same at any wavelength. Endoscope system. The biological function information is oxygen saturation calculated based on the measurement signal ratio between the first signal image signal and the second signal image signal after correction.
The reference information is a reference signal ratio indicating the ratio between the first reference image signal and the second reference image signal,
The reference signal ratio is changed according to an inter-frame intensity ratio indicating a ratio of the intensity of the reflected light of the first illumination light to the intensity of the reflected light of the second illumination light. Endoscope system. A first light source emitting a first illumination light including a first signal light and a first reference light; a second illumination light including a second signal light having a wavelength range different from the first signal light; and a second reference light A light source control unit that controls generation timings of the first illumination light and the second illumination light such that the first illumination light and the second illumination light are alternately emitted to the subject; During illumination of the specimen by the first illumination light, the first signal light is captured by wavelength-dividing the reflected light of the first illumination light into the first signal light and the first reference light. And outputting a first reference image signal corresponding to the first reference light, and during illumination of the sample by the second illumination light, By separating the reflected light of the illumination light into the second signal light and the second reference light for imaging, the second light can be obtained. And it outputs a second signal for the image signal corresponding to the issue light, and the processor unit of the endoscope system and an image pickup unit that outputs a second reference picture signal corresponding to the second reference beam,
A first alignment unit that calculates an amount of positional deviation between the first signal image signal and the second signal image signal, and performs alignment between the signal image signals;
A second alignment unit that aligns the first reference image signal and the second reference image signal based on the positional shift amount;
A reference information calculation unit that calculates reference information on the intensity of the first and second signal light for each pixel based on the first reference image signal and the second reference image signal that have been aligned;
A correction unit that corrects the first signal image signal or the second signal image signal based on the reference information;
A biological function information calculation unit which calculates biological function information based on the first signal image signal or the second signal image signal after correction;
A processor unit of an endoscope system comprising: The light source control unit is configured to differ a first illumination light including a first signal light and a first reference light, and a second illumination light including a second signal light and a second reference light different in wavelength range from the first signal light. A control step of controlling generation timings of the first illumination light and the second illumination light so as to occur at timings;
The imaging unit separates the reflected light of the first illumination light into the first signal light and the first reference light during imaging of the reflected light of the first illumination light during imaging of the sample by the first illumination light. An image signal for the first signal corresponding to the first signal light is output, and an image signal for the first reference corresponding to the first reference light is output, and during illumination of the sample by the second illumination light, An image signal for a second signal corresponding to the second signal light is output by wavelength-dividing the reflected light of the second illumination light into the second signal light and the second reference light; An imaging step of outputting a second reference image signal corresponding to the second reference light;
A first alignment step in which a first alignment unit calculates an amount of positional deviation between the first signal image signal and the second signal image signal and performs alignment between the signal image signals;
A second alignment step in which a second alignment unit aligns the first reference image signal and the second reference image signal based on the positional shift amount;
A reference information calculation unit calculates reference information on the intensity of the first and second signal light for each pixel based on the first reference image signal and the second reference image signal that have been aligned. Information calculation step;
A correction step of correcting the first signal image signal or the second signal image signal based on the reference information;
A biological function information calculating step of calculating biological function information based on the corrected first signal image signal or the second signal image signal, the biological function information calculation unit;
A method of operating an endoscope system comprising:

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