JP2015054062A - Endoscope system, processor device, light source device, and operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce artifact in degree of oxygen saturation occurred in magnified observation.SOLUTION: A light source device 14 of an endoscope system 10 may emit signal light of A emission pattern in which signal light Lhaving center wavelength λand signal light Lhaving center wavelength λare respectively irradiated on a sample and signal light of B emission pattern in which signal light Lhaving center wavelength λand signal light Lhaving center wavelength λare respectively irradiated on the sample. Each of the wavelengths λ, λ, λ, λsatisfy |λ-λ|>|λ-λ|. An oxygen saturation degree image creating part 76 comprises an oxygen saturation degree calculation part 83. The oxygen saturation degree calculation part 83 calculates the degree of oxygen saturation in every pixels based on the ratio between each of image signals in an identical pixel which were obtained with reflected light of the signal light Land the signal light Lin the case of the A emission pattern and reflected light of the signal light Land the signal light Lin the case of B emission pattern. A controlling part 67 executes switch of emission pattern of the light source device 14 between the A emission pattern and the B emission pattern.

Description

  The present invention relates to an endoscope system, a processor device, a light source device, and an operation method for obtaining biological function information related to oxygen saturation of blood hemoglobin from an image signal obtained by imaging in a specimen.

  In the medical field, diagnosis is generally performed using an endoscope system including a light source device, an endoscope, and a processor device. In recent years, lesions are being diagnosed using the oxygen saturation of blood hemoglobin in the biological function information. As a method for obtaining the oxygen saturation level of blood hemoglobin, the first signal light and the second signal light having different wavelength bands and absorption coefficients of oxyhemoglobin and deoxyhemoglobin are alternately irradiated on the blood vessels in the mucous membrane, A method is known in which each reflected light of the first signal light and the second signal light is detected by an image sensor at the distal end of an endoscope (Patent Document 1).

  The ratio of the first signal light image signal corresponding to the reflected light of the first signal light detected by the image sensor and the second signal light image signal corresponding to the reflected light of the second signal light (hereinafter referred to as signal ratio) is A constant value is maintained if there is no change in the oxygen saturation in the blood vessel, but if there is a change in the oxygen saturation, it also changes accordingly. Therefore, the oxygen saturation can be calculated based on the signal ratio between the first signal light image signal and the second signal light image signal.

  In addition, the endoscope system of Patent Literature 1 observes the first signal light and the second signal light irradiated to calculate the oxygen saturation according to the depth of the blood vessel to be observed and the oxygen saturation is calculated. Switching automatically. Specifically, when calculating the oxygen saturation of the superficial blood vessel, two of the three types of narrowband light of 405 nm, 445 nm, and 473 nm are used as the first signal light and the second signal light. In addition, two of the 540 nm, 550 nm, and 580 nm narrowband light are used to calculate the oxygen saturation of the middle layer blood vessel, and two of the 680 nm, 805 nm, and 950 nm narrowband light are used for the deep layer blood vessel. ing.

JP 2012-213550 A

  The calculation of the oxygen saturation is based on the premise that the first and second signal lights are uniformly irradiated on the specimen. For this reason, if the first and second signal lights are non-uniform, the reliability of the calculated oxygen saturation is low, so in an endoscope system that acquires oxygen saturation, the specimen is irradiated almost uniformly. As described above, the irradiation range of the first and second signal lights, the distribution of the light amount, and the like are strictly adjusted in advance.

  However, when observing with normal white light, even when the irradiation range and light intensity distribution are adjusted so that the specimen can be clearly observed in the entire observation range, when oxygen saturation is calculated, In some cases, a large error (hereinafter referred to as artifact) that does not depend on the properties of the specimen appears. Specifically, when switching from non-magnifying observation to magnifying observation (observation in which the tip of the endoscope is very close to the specimen, or observation that magnifies the specimen by operating the zoom lens), it does not appear during non-magnifying observation A low oxygen region or a high oxygen region appears. That is, at the time of magnification observation, an artifact of oxygen saturation that could not occur at the time of non-magnification observation appears. This is because the oxygen saturation is extremely sensitive to the light quantity distribution of the first and second signal lights, and even when the distribution (error) is very small, the oxygen saturation level is increased according to the enlargement ratio at the time of magnification observation. The main cause is that the contribution of

  In order to prevent the oxygen saturation artifact from appearing during magnified observation, the first and second signal lights may be irradiated more uniformly, but of course, it is impossible to achieve uniform uniformity. is there. Even if the oxygen saturation artifact is prevented from appearing during magnification observation at a predetermined magnification, the same problem occurs again if the magnification is increased.

  It is an object of the present invention to provide an endoscope system, a processor device, a light source device, and an operation method that reduce an oxygen saturation artifact that appears during magnified observation and accurately calculate and display the oxygen saturation.

The endoscope system of the present invention includes a light source device, an image sensor, an oxygen saturation calculation unit, and a control unit. Light source device, the central wavelength lambda _A1 of the signal light _{L A1} and the center wavelength lambda _A2 and A luminescent pattern for irradiating a signal light _{L A2} to sample each of the center wavelength lambda _B1 signal light _{L B1} and the center wavelength lambda _B2 signal in Signal light can be emitted with the B light emission pattern for irradiating the specimen with the light L _B2 . The light source device satisfies | λ _A1 −λ _A2 |> | λ _B1 −λ _B2 | with respect to each of the center wavelengths λ _A1 , λ _A2 , λ _B1 , and λ _B2 . The image sensor images the specimen with each reflected light of the signal lights L _A1 , L _A2 , L _B1 , and L _B2 and outputs an image signal. When the light emission pattern of the light source device is the A light emission pattern, the oxygen saturation calculator calculates the pixel based on the ratio of the image signals of the same pixel obtained by the reflected light of the signal light L _A1 and the signal light L _A2. Oxygen saturation is calculated every time, and when the light emission pattern of the light source device is a B light emission pattern, it is based on the ratio of each image signal of the same pixel obtained by the reflected light of the signal light L _B1 and the signal light L _B2 The oxygen saturation is calculated for each pixel. The control unit switches the light emission pattern of the light source device between the A light emission pattern and the B light emission pattern.

A mode table representing the correlation between the ratio of each image signal obtained by the reflected light of the signal light L _A1 and the reflected light L _A2 and the oxygen saturation, and the reflected light of the signal light L _B1 and the signal light L _B2 You may provide the correlation memory | storage part which memorize | stores the ratio of each obtained image signal, and the B mode table showing the correlation of oxygen saturation. In this case, the oxygen saturation calculation unit calculates the oxygen saturation using the A mode table when the light emission pattern of the light source device is the A light emission pattern, and B when the light emission pattern of the light source device is the B light emission pattern. The oxygen saturation is calculated using the mode table.

  You may provide the zoom lens which expands or reduces the image of the test object imaged on an image sensor, and the zoom detection part which monitors operation | movement of a zoom lens. In this case, the control unit switches between the A emission mode and the B emission mode according to the detection result by the zoom detection unit.

  In addition, when performing non-magnification observation in which the image of the specimen is most reduced by the zoom lens, the control unit changes the light emission pattern of the light source device to the A light emission pattern and performs magnified observation in which the specimen image is enlarged by the zoom lens. Moreover, it is preferable that the light emission pattern of the light source device is a B light emission pattern.

  An artifact detection unit that detects an artifact that is an error in oxygen saturation regardless of the property of the specimen may be provided. In this case, the control unit sets the light emission mode of the light source device to the A light emission mode when the artifact detection unit does not detect the artifact, and sets the light emission mode of the light source device to the B light emission mode when the artifact detection unit detects the artifact.

  You may provide the light emission mode switching operation part which switches the light emission mode of a light source device manually. In this case, a control part switches the light emission mode of a light source device with A light emission mode and B light emission mode based on operation of the light emission mode switching operation part.

  Further, a distance measuring sensor that measures the distance between the distal end portion of the endoscope on which the image sensor is mounted and the sample may be provided. In this case, the control unit switches the light emission mode of the light source device between the A light emission mode and the B light emission mode according to the distance between the distal end portion measured by the distance measuring sensor and the sample.

The signal light L _B1 may be narrowband light. Further, the signal light L _B2 may be narrow band light. Narrow band light means light having an extremely narrow wavelength band with a half-value width of about ± 10 nm.

The center wavelengths λ _B1 and λ _B2 of the signal light L _B1 and the signal light L _B2 belong to the same wavelength band, for example. In this case, for example, it is preferable that the center wavelengths λ _B1 and λ _B2 of the signal light L _B1 and the signal light L _B1 both belong to the blue wavelength band. Note that the same color means that when the wavelength band of visible light is divided into blue (380 to 560 nm), green (450 to 630 nm), and red (580 to 760 nm), these wavelength bands belong to the same wavelength band. Say. Blue means a wavelength band of 380 to 560 nm.

The center wavelength lambda _B2 of the signal light L _B2 is, for example, the wavelength of the isosbestic point extinction coefficient of oxyhemoglobin and reduced hemoglobin are equal.

Another endoscope system of the present invention also includes a light source device, an image sensor, an oxygen saturation calculation unit, and a control unit. However, the light source apparatus, the signal light _{L A1} having a wavelength band _{W A1,} and A light-emitting pattern which irradiates the signal light _{L A2} to sample each having a wavelength band _{W A2,} the signal light L having a wavelength band _{W B1 B1} and signal light L _B2 having a wavelength band W _B2 can emit signal light with a B light emission pattern that irradiates the specimen, and the absorption coefficient of hemoglobin is expressed in each wavelength band W _A1 , W _A2 , W _B1 , When the values integrated with W _B2 are S _A1 , S _A2 , S _B1 , and S _B2 , the respective wavelength bands W _A1 , W _A2 , W _B1 , and W _B2 are | S _A1 −S _A2 |> | S _B1 − S _B2 | is satisfied. The image sensor images the specimen with each reflected light of the signal lights L _A1 , L _A2 , L _B1 , and L _B2 and outputs an image signal. When the light emission pattern of the light source device is the A light emission pattern, the oxygen saturation calculator calculates the pixel based on the ratio of the image signals of the same pixel obtained by the reflected light of the signal light L _A1 and the signal light L _A2. Oxygen saturation is calculated every time, and when the light emission pattern of the light source device is a B light emission pattern, it is based on the ratio of each image signal of the same pixel obtained by the reflected light of the signal light L _B1 and the signal light L _B2 The oxygen saturation is calculated for each pixel. The control unit switches the light emission pattern of the light source device between the A light emission pattern and the B light emission pattern.

Operation method of the endoscope system of the present invention, the A light emission pattern that emits signal light L _A2 of the signal light L _A1 and the center wavelength lambda _A2 of the central wavelength lambda _A1, the signal light L _B1 and the center wavelength of the center wavelength lambda _B1 is capable of emitting signal light and the B light-emitting pattern which emits signal light _{L B2} of lambda _B2, respective central wavelength _{λ A1, λ A2, λ B1} , with respect to _{λ B2 | λ A1 -λ A2 |} > | λ B1 -λ _A light source device that satisfies _B2 |, an image sensor that images a specimen with each reflected light of each of the signal lights L _A1 , L _A2 , L _B1 , and L _B2 and outputs an image signal, and a light emission pattern of the light source device emits A light In the case of the pattern, the oxygen saturation is calculated for each pixel based on the ratio of the image signals of the same pixel obtained by the reflected light of the signal light L _A1 and the signal light L _A2 , and the light emission pattern of the light source device is B in the case of the emission pattern, the signal light L _B In operation method of the endoscope system provided with an oxygen saturation calculating unit for calculating oxygen saturation for each pixel based on the ratio of the image signals of the same pixel obtained by the reflected light of the signal light L _B2 and A first light emission pattern switching step for switching the light emission pattern of the light source device from the A light emission pattern to the B light emission pattern is provided.

  Moreover, the 2nd light emission pattern switching step which switches the light emission pattern of a light source device from B light emission pattern to A light emission pattern is provided.

A light source device of the present invention, the A light emission pattern for irradiating a signal light L _A2 of the signal light L _A1 and the center wavelength lambda _A2 of the central wavelength lambda _A1 to sample each center wavelength lambda _B1 signal light L _B1 and the center wavelength lambda _B2 of the signal light _{L B2} is capable of emitting signal light and the B light emission pattern to be irradiated to the specimen, respectively, each center wavelength _{λ A1, λ A2, λ B1} , with respect to _{λ B2 | λ A1 -λ A2 |} > | λ _B1 −λ _B2 | is satisfied.

Processor device of the present invention, the A light emission pattern that emits signal light _{L A2} of the signal light _{L A1} and the center wavelength lambda _A2 of the central wavelength lambda _A1, the center wavelength lambda _B1 signal light _{L B1} and the center wavelength lambda _B2 signal light of A light source that can emit signal light with a B light emission pattern that emits L _B2 and satisfies | λ _A1 −λ _A2 |> | λ _B1 −λ _B2 | with respect to each of the center wavelengths λ _A1 , λ _A2 , λ _B1 , and λ _B2. A processor device of an endoscope system including a device and an image sensor that images a specimen with each reflected light of each of the signal lights L _A1 , L _A2 , L _B1 , and L _B2 and outputs an image signal When the light emission pattern of the device is the A light emission pattern, the oxygen saturation is calculated for each pixel based on the ratio of each image signal of the same pixel obtained by the reflected light of the signal light L _A1 and the signal light L _A2. , Light emission pattern of light source device In the case of B emission pattern signal light L _B1 and the signal light L oxygen saturation calculating unit for calculating oxygen saturation for each pixel based on the ratio of the image signals of the same pixel obtained by the reflected light _B2 Is provided.

  According to the endoscope system, processor device, and operation method of the present invention, it is possible to reduce the oxygen saturation artifact during magnified observation and accurately calculate and display the oxygen saturation.

It is an external view of an endoscope system. It is a block diagram of an endoscope system. It is a top view of a rotation filter. It is a graph which shows the spectral transmittance of a RGB color filter. It is explanatory drawing which shows the imaging control at the time of normal observation mode. It is explanatory drawing which shows the imaging control in the case of performing special observation mode by A mode. It is explanatory drawing which shows the imaging control in the case of performing special observation mode by B mode. It is a block diagram of an oxygen saturation image generation part. It is a graph which shows the correlation of signal ratio B1 ₍₄₇₀₎ / G2, R2 / G2 memorize | stored in the A mode table, and oxygen saturation. It is a graph which shows the correlation with signal ratio B1 ₍₄₇₀₎ / G2, R3 / G3 memorize | stored in B mode table, and oxygen saturation. It is a graph which shows the light absorption coefficient of oxygenated hemoglobin and reduced hemoglobin. It is explanatory drawing which shows the method of calculating oxygen saturation. It is a flowchart which shows the effect | action of an endoscope system. It is explanatory drawing which shows the oxygen saturation image produced | generated by A mode and B mode. It is a block diagram of the endoscope system of a 2nd embodiment. It is a block diagram of the endoscope system of the modification which provided the ranging sensor. It is a top view of the rotation filter of a 3rd embodiment. It is a graph which shows the spectral transmittance of a band pass filter. It is explanatory drawing which shows the imaging control of B mode in the case of using the rotation filter of 3rd Embodiment. It is a block diagram of the endoscope system of a 4th embodiment. It is a block diagram of the endoscope system of a 5th embodiment. It is a graph which shows the spectrum of 1st-3rd white light. It is explanatory drawing which shows the imaging control in the normal mode and A mode of 5th Embodiment. It is explanatory drawing which shows the imaging control of B mode of 5th Embodiment.

[First Embodiment]
As shown in FIG. 1, the endoscope system 10 according to 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 includes an insertion portion 21 to be inserted into a specimen, an operation portion 22 provided at a proximal end portion of the insertion portion 21, a bending portion 23 and a distal end portion 24 provided on the distal end side of the insertion portion 21. have. By operating the angle knob 22a of the operation unit 22, the bending unit 23 performs a bending operation. With this bending operation, the distal end portion 24 is directed in a desired direction.

  In addition to the angle knob 22a, the operation unit 22 is provided with a mode switching SW (mode switching switch) 22b and a zoom operation unit 22c.

  The mode switching SW 22b is used for switching operation between two types of modes, a normal observation mode and a special observation mode. The normal observation mode is a mode in which a normal light image in which the inside of the specimen is converted into a full color image 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 specimen is displayed on the monitor 18. The endoscope system 10 further includes two sub modes (hereinafter referred to as A mode and B mode) as special observation modes. A mode and B mode differ in the wavelength band of the light irradiated to the specimen and the method of calculating the oxygen saturation. The endoscope system 10 automatically switches between the A mode and the B mode. For this reason, the doctor who uses the endoscope system 10 is appropriately switched between the A mode and the B mode only by setting the special observation mode by the mode switching SW 22b, and an appropriate oxygen saturation image is displayed on the monitor 18. The

  The zoom operation unit 22c is used for a zoom operation for driving the zoom lens 47 (see FIG. 2) in the endoscope 12 to enlarge the specimen.

  The processor device 16 is electrically connected to the monitor 18 and the console 20. The monitor 18 displays images such as normal light images and oxygen saturation images, and information related to these images (hereinafter referred to as image information and the like). The console 20 functions as a UI (user interface) that receives input operations such as function settings. Note that a recording unit (not shown) for recording image information or the like may be connected to the processor device 16.

  As shown in FIG. 2, the light source device 14 includes a broadband light source 31, a rotary filter 32, and a filter control unit 33. The broadband light source 31 includes, for example, a xenon lamp, a white LED, and the like, and emits white light whose wavelength band ranges from blue to red. White light emitted from the broadband light source 31 is incident on a light guide (LG) 41 via an optical member (all not shown) such as a condenser lens, an optical fiber, and a multiplexer.

  The rotary filter 32 is detachably provided on the white light path incident on the light guide 41 from the broadband light source 31. When the rotary filter 32 is inserted on the white light path, the rotation filter 32 adjusts the frame rate of imaging by the image sensor 48. It is rotated synchronously. More specifically, in the normal observation mode, it is retracted from the white light optical path, and in the special observation mode, it is inserted into the white light optical path. For this reason, in the normal observation mode, the white light emitted from the broadband light source 31 is directly incident on the light guide 41 without being limited in wavelength band, and is irradiated onto the specimen. On the other hand, in the special observation mode, white light emitted from the broadband light source 31 may be incident on the light guide 41 with the wavelength band limited by the rotary filter 32. In this case, the sample is irradiated with light in a part of the wavelength band included in the white light.

  As shown in FIG. 3, the rotary filter 32 includes an A mode filter 32a and a B mode filter 32b. When the special observation mode is set, either the A mode filter 32 a or the B mode filter 32 b is arranged on the optical path of white light emitted from the broadband light source 31. That is, in the special observation mode, the light source device 14 switches between the two light emission modes of the A light emission mode and the B light emission mode depending on whether the A mode filter 32a or the B mode filter 32b is arranged on the optical path of the broadband light source 31. Is possible. The A light emission mode is a light emission mode in which the A mode filter 32 a is disposed on the optical path of the broadband light source 31, and the B light emission mode is a light emission mode in which the B mode filter 32 b is disposed on the optical path of the broadband light source 31. Note that, when the endoscope system 10 executes the special observation mode in the A mode, the light emission mode of the light source device 14 is controlled to the A light emission mode, and the endoscope system 10 executes the special observation mode in the B mode. In addition, the light emission mode of the light source device 14 is controlled to the B light emission mode.

  The A mode filter 32a is provided, for example, on the inner peripheral portion of the rotary filter 32, and includes a first narrowband light transmitting portion 33a that selectively transmits first narrowband light (470 ± 10 nm) having a center wavelength of 470 nm, and a wavelength band. And an aperture 33b that allows the entire wavelength band of white light to pass therethrough. For this reason, in the A emission mode, the light applied to the specimen is alternately switched for each frame between the white light and the first narrowband light.

In the A mode in which the light source device 14 is controlled to the A emission mode, a signal between an image signal obtained by imaging with the first narrowband light and an image signal obtained by imaging in the green wavelength band included in the white light. Oxygen saturation is calculated based on the ratio. That is, the first narrowband light wavelength (wavelength band) is a first signal light (A-mode first signal light) L _A1 used for calculating the oxygen saturation in the A mode, the image signal obtained specimens The wavelength varies depending on the oxygen saturation. The light in the green wavelength band included in the white light (broadband green light having a center wavelength of about 560 nm and about 450 to 630 nm) is the second signal light L _B1 for A mode.

  The wavelength of the first narrowband light is suitable for the case where oxygen saturation is calculated by imaging from a distant view without enlarging the specimen. In other words, the purpose of obtaining oxygen saturation information during non-magnifying observation is often to examine the overall properties of the specimen, not about fine tissue units such as surface blood vessels, middle blood vessels, and deep blood vessels. The first narrow-band light has a certain degree of depth, and the wavelength band is selected so that the oxygen saturation that reflects not only the surface layer but also the oxygen saturation of blood vessels in the middle to deep layers can be calculated.

  The B-mode filter 32b is provided, for example, on the outer periphery of the rotary filter 32, and has a second narrowband light transmitting portion 34a that selectively transmits second narrowband light (440 ± 10 nm) having a center wavelength of 440 nm, and a center wavelength of 450 nm. The third narrow-band light transmitting portion 34b that selectively transmits the third narrow-band light (450 ± 10 nm), and an opening 34c that allows the entire wavelength band of white light to pass through without limiting the wavelength band. For this reason, in the B emission mode, the light irradiated to the specimen is switched in turn for each frame of the second narrowband light, the third narrowband light, and the white light.

In the A mode in which the light source device 14 is controlled to the A light emission mode, the light source device 14 calculates the oxygen saturation based on the signal ratio of the image signal by the first narrowband light and the image signal by the green broadband light. In the B mode controlled to the B emission mode, the oxygen saturation is calculated based on the signal ratio of the image signal based on the second narrowband light and the image signal based on the third narrowband light. That is, the second narrowband light is the first signal light L _B1 for B mode, and the wavelength (wavelength band) of the second narrowband light is a wavelength at which the obtained image signal changes according to the oxygen saturation of the specimen. It is stipulated in. The third narrowband light is the second signal light L _B2 for B mode. The wavelength 450 nm of the third narrowband light is a wavelength at an isosbestic point where the absorption coefficients of oxyhemoglobin and reduced hemoglobin are substantially equal (see FIG. 11).

However, each wavelength band of the second narrowband light and the third narrowband light, which are the first and second signal lights L _B1 and L _B2 for the B mode, has an accurate oxygen saturation when the specimen is magnified. It is determined so that it can be calculated. That is, when the specimen is enlarged and observed by zooming with an optical system or by bringing the tip of the endoscope close, an artifact may appear in the oxygen saturation, but the second narrowband light and the third narrowband Each wavelength band of light calculates accurate oxygen saturation by reducing artifacts compared to the case of calculating oxygen saturation using A-mode first narrowband light and green broadband light at least during magnified observation Chosen to be able to.

Specifically, the center wavelength of the first narrowband light that is the first signal light L _A1 in the A emission mode is λ _A1 (= 470 nm), and the center wavelength of the green wavelength band that is the second signal light L _A2 is λ _A2. (≈560 nm), the central wavelength of the second narrowband light that is the first signal light L _B1 in the B emission mode is λ _B1 (= 440 nm), and the central wavelength of the third narrowband light that is the second signal light L _B2 When λ _B2 (= 450 nm), the second narrowband light and the third wavelength are set so that each of these center wavelengths λ1 to λ4 satisfies the relationship | λ _A1 −λ _A2 |> | λ _B1 −λ _B2 |. The center wavelengths λ _B1 and λ _{B2 of the} narrowband light are determined.

  Artifacts that appear during magnified observation are due to the distribution (non-uniformity) of the light amounts of the first and second signal lights irradiated to calculate the oxygen saturation, and this distribution appears in accordance with the wavelength. Is different. For example, when two wavelength bands having a large center wavelength are used, such as the first narrow-band light in A mode and the green broadband light in white light, the amount of light in the blue wavelength band and the green wavelength band is large during observation. The difference in distribution is likely to be noticeable. For this reason, artifacts appear when the oxygen saturation is calculated based on the signal ratio of the image signals obtained with the first narrowband light and the green broadband light in the white light during the magnification observation.

  On the other hand, when the first and second signal lights having the center wavelength satisfying the above relationship and the close wavelength bands are used as in the second narrow band light and the third narrow band light in the B mode, depending on the wavelength band by the enlarged observation. Even if different distributions of light quantity or the like appear, the difference is reduced as compared with the A mode. For this reason, compared with the case of carrying out magnified observation using the 1st narrow band light and green broadband light whose center wavelengths are far like A mode, an artifact can be suppressed small. In particular, by using the second narrowband light of 440 nm and the third narrowband light of 450 nm as the first and second signal lights for the B mode, artifacts are almost completely suppressed even during magnified observation, and accurate oxygen saturation is achieved. The degree can be calculated.

  In the present embodiment, in the B mode, the second narrowband light and the third narrowband light are used as signal lights for the calculation of oxygen saturation, but instead of these narrowband lights, wavelength bands are used. It is also possible to use broadband light having a wavelength exceeding ± 10 nm.

Further, in the B mode of the present embodiment, it is assumed that the cause of the artifact in oxygen saturation is the distribution of the light amount of the signal light to be irradiated, and the center wavelengths λ of the second and third narrowband lights irradiated in the B mode. _B1, close to lambda _B2, by slightly differences in the distribution of such these light amount, but to suppress artifacts oxygen saturation during magnified observation, artifacts appearing in oxygen saturation during magnified observation It can also be understood that the difference occurs in the distribution of the light amount of the reflected light (light that has been absorbed by the specimen) of the two first and second signal lights used for calculating the oxygen saturation.

  As described above, the difference in distribution of the amount of light generated in the reflected light of the first and second signal lights is caused by the non-uniformity of the first signal light and the second signal light applied to the specimen, as well as the first and second signal lights. This is considered to be caused by a difference in light absorption characteristics between the first signal light and the second signal light. Therefore, if the light-absorbing characteristics of the first signal light and the light-absorbing characteristics of the second signal light are brought close to each other, it is possible to reduce the difference in the distribution of the amount of light generated in the reflected light of the first and second signal lights. That is, if the first signal light and the second signal light are made uniform when they are reflected by the specimen, the oxygen saturation artifact can be eliminated.

The following can be considered as a method for bringing the light absorption characteristics of the first signal light and the light absorption characteristics of the second signal light close together during magnified observation (that is, in the B mode). For example, the value obtained by integrating the absorption coefficient μa (λ) of hemoglobin at the wavelength λ in the wavelength band W is S _W = ∫ _W (μa (λ)) dλ, and an image signal that changes in accordance with the oxygen saturation in the A mode is obtained. The wavelength bands of the first signal light L _A1 and the second signal light L _A2 for A mode to be obtained are W _A1 and W _A2, and B for obtaining an image signal that changes in accordance with oxygen saturation in the B mode. The wavelength bands of the first signal light L _B1 and the second signal light L _B2 for mode are denoted as W _B1 and W _B2 . In addition, the integrated values in the respective wavelength bands W _A1 , W _A2 , W _B1 , and W _B2 are S _A1 , S _A2 , S _B1 , and S _B2 . In this case, the first signal light L _B1 for the B mode and so as to satisfy | S _A1 −S _A2 | >> | S _B1 −S _B2 | for each wavelength band W _A1 , W _A2 , W _B1 , W _B2 and determining the respective wavelength bands _{W B1, W B2} of the second signal light _{L B2.} Thus, by determining the wavelength bands W _A1 , W _A2 , W _B1 , and W _B2 , the difference in the light absorption characteristics of the first and second signal lights in the B mode becomes smaller than that in the A mode. As a result, the reflected light of the first signal light and the second signal light has a slight difference in distribution of the light amount and the like, so that an artifact appearing in the oxygen saturation can be reduced.

Note that the relationship between the integrated values S _A1 , S _A2 , S _B1 , and S _B2 of the wavelength bands W _A1 , W _A2 , W _B1 , and W _B2 is that the normal value of venous oxygen saturation is 60 to 80%. It is sufficient if the above relationship is satisfied within this range, and for example, it is sufficient if the above relationship is satisfied with a central oxygen saturation of 70%.

  The filter control unit 33 inserts and removes the rotary filter 32, switches between the A mode filter 32a and the B mode filter 32b, and the frame rate of the image sensor 48 based on the control signal input from the mode switching SW 22b or the control unit 67. The rotation timing is controlled in accordance with the control.

  The imaging optical system 24b of the endoscope 12 includes an imaging lens 46, a zoom lens 47, and an image sensor 48 (see FIG. 2). Reflected light from the specimen enters the image sensor 48 via the imaging lens 46 and the zoom lens 47. As a result, a reflected image of the specimen is formed on the image sensor 48. The zoom lens 47 moves between the tele end and the wide end by operating the zoom operation unit 22c. When the zoom lens 47 moves to the wide end side, the reflected image of the specimen is enlarged. On the other hand, as the zoom lens 47 moves to the tele end side, the reflected image of the specimen is reduced. Note that when not magnifying observation (non-magnifying observation), the zoom lens 47 is disposed at the telephoto end. When zoom operation is performed by operating the zoom operation unit 22c, the zoom lens 47 is moved from the tele end to the wide end side.

  The image sensor 48 is a color image sensor, captures a reflected image of the specimen, and outputs an image signal. The image sensor 48 is, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor. The image sensor 48 has RGB pixels having an RGB color filter provided on the imaging surface, and outputs R, G, and B image signals by performing photoelectric conversion on the RGB pixels. To do.

  As shown in FIG. 4, 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 spectral transmission of the R color filter 580 to 760 nm. Have a rate. Therefore, when the white light emitted from the broadband light source 31 is irradiated without being limited, the B pixel, G pixel, and R pixel receive light in the wavelength band of the corresponding color filter. In the special observation mode, the specimen is irradiated with the first narrowband light in the A mode, and the second and third narrowband lights in the B mode. Light is received by the B pixel.

  As the image sensor 48, a so-called complementary color image sensor provided with complementary color filters of C (cyan), M (magenta), Y (yellow), and G (green) on the imaging surface may be used. When a complementary color image sensor is used as the image sensor 48, any of the endoscope 12, the light source device 14, and the processor device 16 is used as a color conversion unit that performs color conversion from four CMYG image signals to three RGB image signals. You should set it up. In this way, even when a complementary color image sensor is used, it is possible to obtain RGB three-color image signals by color conversion from the four-color CMYG image signals.

  The imaging control unit 49 performs imaging control of the image sensor 48. As shown in FIG. 5, a period of one frame of the image sensor 48 includes an accumulation period for photoelectrically converting reflected light from the specimen and accumulating charges, and a readout period for reading the accumulated charges and outputting an image signal thereafter. It consists of. In the normal observation mode, the specimen irradiated with white light is imaged by the image sensor 48 for each frame period. Thus, RGB image signals are output from the image sensor 48 for each frame.

  In the special observation mode, the imaging control unit 49 causes the image sensor 48 to perform the accumulation period and the readout period in the same manner as in the normal observation mode. Thereby, in the case of the A mode of the special observation mode, the image sensor 48 receives the first narrowband in the first frame in response to the first narrowband light and the white light being alternately irradiated as shown in FIG. The specimen is imaged with light, and in the next second frame, the specimen is imaged with white light and an image signal is output. Since the light emitted in the first frame is only the first narrowband light, the B pixel receives the reflected light of the first narrowband light, but the G pixel and the R pixel do not receive the reflected light from the specimen. Therefore, a significant image signal output from the image sensor 48 in the first frame is substantially a B image signal obtained from B pixels. On the other hand, since the second frame is irradiated with white light including all the blue, green, and red wavelength ranges, the B image signal obtained with the B pixel, the G image signal obtained with the G pixel, and the R pixel are obtained. Each R image signal is output.

In this specification, each image signal is described with a frame number. Further, the image signal obtained by the reflected light of the narrow band light is described with the center wavelength of the narrow band light. What does not have a center wavelength notation is an image signal by broadband light. Therefore, in the A mode, the image sensor 48 outputs a B1 ₍₄₇₀₎ image signal in the first frame, and outputs a B2 image signal, a G2 image signal, and an R2 image signal in the second frame.

As shown in FIG. 7, in the B mode of the special observation mode, the second narrowband light, the third narrowband light, and the white light are sequentially emitted for each frame. The specimen is imaged with the second narrowband light, and a B1 ₍₄₄₀₎ image signal is output. In the next second frame, the specimen is imaged with the third narrowband light, and a B2 ₍₄₅₀₎ image signal is output. In the third frame, the specimen is imaged with white light, and a B3 image signal, a G3 image signal, and an R3 image signal are output.

  The image signals of the respective colors output from the image sensor 48 are transmitted to a CDS (correlated double sampling) / AGC (automatic gain control) circuit 50 (see FIG. 2). The CDS / AGC circuit 50 performs correlated double sampling (CDS) and automatic gain control (AGC) on the analog image signal output from the image sensor 48. The image signal that has passed through the CDS / AGC circuit 50 is converted into an image signal having a gradation suitable for an output device such as the monitor 18 by being subjected to gamma conversion by the gamma conversion unit 51. The image signal after the gamma conversion is converted into a digital image signal by the A / D converter 52. The digitized image signal is input to the processor device 16.

  The processor device 16 includes a receiving unit 54, an image processing switching unit 60, a normal observation image processing unit 62, a special observation image processing unit 64, an image display signal generation unit 66, and a control unit 67. . The receiving unit 54 receives an image signal input from the endoscope 12. The receiving unit 54 includes a DSP (Digital Signal Processor) 56 and a noise removing unit 58, and the DSP 56 performs digital signal processing such as color correction processing on the received image signal. The noise removal unit 58 performs noise removal processing by, for example, a moving average method or a median filter method on the image signal that has been subjected to color correction processing or the like by the DSP 56. The image signal from which the noise has been removed is input to the image processing switching unit 60.

  The image processing switching unit 60 inputs an image signal to the normal observation image processing unit 62 when the mode switching SW 22b is set to the normal observation mode. On the other hand, when the mode switching SW 22 b is set to the special observation mode, the image processing switching unit 60 inputs an image signal to the special observation image processing unit 64.

  The normal observation image processing unit 62 includes a color conversion unit 68, a color enhancement unit 70, and a structure enhancement unit 72. The color conversion unit 68 generates RGB image data in which the input RGB image signals for one frame are assigned to R pixels, G pixels, and B pixels, respectively. The RGB image data is further subjected to color conversion processing such as 3 × 3 matrix processing, gradation conversion processing, and three-dimensional LUT processing.

  The color enhancement unit 70 performs various color enhancement processes on the RGB image data that has been subjected to the color conversion process. The structure enhancement unit 72 performs structure enhancement processing such as spatial frequency enhancement on the RGB image data that has been subjected to color enhancement processing. The RGB image data subjected to the structure enhancement process by the structure enhancement unit 72 is input to the image display signal generation unit 66 as a normal observation image.

  The special observation image processing unit 64 includes an oxygen saturation image generation unit 76 and a structure enhancement unit 78. The oxygen saturation image generation unit 76 calculates the oxygen saturation and generates an oxygen saturation image representing the calculated oxygen saturation.

  The structure enhancement unit 78 performs structure enhancement processing such as spatial frequency enhancement processing on the oxygen saturation image input from the oxygen saturation image generation unit 76. The oxygen saturation image that has undergone the structure enhancement processing by the structure enhancement unit 72 is input to the image display signal generation unit 66.

  The display image signal generation unit 66 converts the normal observation image or the oxygen saturation image into a display format signal (display image signal) and inputs it to the monitor 18. As a result, the normal observation image or the oxygen saturation image is displayed on the monitor 18.

  The control unit 67 operates when the special observation mode is set by the mode switching SW 22b, determines whether to execute the special observation mode in the A mode or the B mode, and corresponds to the determined sub mode. The operation is performed by the light source device 14 and the oxygen saturation image generation unit 76.

  Specifically, the control unit 67 includes a zoom detection unit 67a. The zoom detection unit 67a monitors the operation of the zoom operation unit 22c and detects the operation of the zoom lens (that is, whether or not magnified observation is performed). Then, the light emission mode of the light source device 14 is switched between the A light emission mode and the B light emission mode according to the detection result by the zoom detection unit 67a. Specifically, when the zoom operation is not detected, the control unit 67 controls the filter control unit 33 to set the light emission mode of the light source device 14 to the A light emission mode. On the other hand, when a zoom operation is detected, the control unit 67 controls the filter control unit 33 to set the light emission mode of the light source device 14 to the B light emission mode. Note that the control unit 67 also switches the processing mode of each unit of the oxygen saturation image generation unit 76 according to the detection result by the zoom detection unit 67a. Specifically, when the zoom operation is not detected, the processing mode of each unit of the oxygen saturation image generation unit 76 is set to the A processing mode, and when the zoom operation is detected, the B processing mode is set.

As shown in FIG. 8, the oxygen saturation image generation unit 76 includes a signal ratio calculation unit 81, a correlation storage unit 82, an oxygen saturation calculation unit 83, and an image generation unit 84. Among these, the signal ratio calculation unit 81 and the oxygen saturation calculation unit 83 perform different operations depending on whether the special observation mode is executed in the A mode or the B mode. That is, the signal ratio calculation unit 81 and the oxygen saturation calculation unit 83 perform the A processing mode when the special observation mode is executed in the A mode and the B when the special observation mode is executed in the B mode. The processing mode can be switched between processing modes. When the special observation mode is executed in the A mode, the oxygen saturation image generation unit 76 stores the B1 ₍₄₇₀₎ image signal acquired in the first frame, the B2 image signal and the G2 image acquired in the second frame. Signal and R2 image signal are input. When the special observation mode is executed in the B mode, the oxygen saturation image generation unit 76 has a B1 ₍₄₄₀₎ image signal acquired in the first frame, a B2 ₍₄₅₀₎ image signal in the second frame, The B3 image signal, G3 image signal, and R3 image signal of the third frame are input as one set.

The signal ratio calculation unit 81 calculates a signal ratio of image signals used for calculating oxygen saturation. Specifically, when the special observation mode is executed in the A mode, the signal ratio calculation unit 81 performs the signal ratio B1 ₍₄₇₀₎ / G2 between the B1 ₍₄₇₀₎ image signal and the G2 image signal, the R2 image signal, and the G2 The signal ratio R2 / G2 of the image signal is calculated for each pixel (A processing mode). On the other hand, when the special observation mode is executed in the B mode, the signal ratio calculation unit 81 calculates the signal ratio B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ between the B1 ₍₄₄₀₎ image signal and the B2 ₍₄₅₀₎ image signal. The signal ratio R3 / G3 between the R3 image signal and the G3 image signal is calculated for each pixel (B processing mode).

  The correlation storage unit 82 stores a table representing the correlation between the signal ratio calculated by the signal ratio calculation unit 81 and the oxygen saturation. Corresponding to the special observation mode being executed in one of the two sub-modes of the A mode and the B mode, the correlation storage unit 82 stores the A mode table 82a for the A mode and the B mode for the B mode. Two tables 82b are stored.

As shown in FIG. 9, the A mode table 82a is an isoline showing the correlation between the two signal ratios B1 ₍₄₇₀₎ / G2, R2 / G2 calculated in the A mode and the oxygen saturation in a two-dimensional space. Is a two-dimensional table defined in The signal ratio B1 ₍₄₇₀₎ / G2 and the signal ratio R2 / G2 and the position and shape of the oxygen saturation isolines are obtained in advance by a physical simulation of light scattering. It varies depending on the amount (signal ratio R2 / G2). The correlation between the signal ratio B1 ₍₄₇₀₎ / G2 and the signal ratio R2 / G2 and the oxygen saturation is stored on a log scale.

As shown in FIG. 10, the B-mode table 82b is a two-dimensional space that shows the correlation between the two signal ratios B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ and R3 / G3 calculated in the B mode and the oxygen saturation. It is a two-dimensional table defined with isolines above. The B mode table 82b is different from the A mode table 82a in that the oxygen saturation increases as the signal ratio B1 ₍₄₇₀₎ / G2 increases. This is because the absorption coefficient of oxyhemoglobin is larger than that of reduced hemoglobin at the wavelength of the first narrowband light used in the A mode, whereas oxyhemoglobin is expressed at the wavelength of the second narrowband light used in the B mode. This is because the extinction coefficient of is smaller than that of reduced hemoglobin (see FIG. 11). Other than this, it is the same as the A mode table 82a, and the positions and shapes of the isolines of the B mode table 82b are obtained in advance by a physical simulation of light scattering. It varies according to the signal ratio R3 / G3). Further, the correlation between the signal ratio B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ and the signal ratio R3 / G3 and the oxygen saturation is stored in a log scale.

Note that, as shown in FIG. 11, the correlation is closely related to the light absorption characteristics and light scattering characteristics of oxyhemoglobin (graph 90) and reduced hemoglobin (graph 91). For example, information on oxygen saturation is easy to handle at wavelengths where the difference in the extinction coefficient between oxyhemoglobin and reduced hemoglobin is large, such as the center wavelength 470 nm of the first narrowband light and the center wavelength 440 nm of the second narrowband light. However, each image signal (B1 ₍₄₇₀₎ image signal, B1 ₍₄₄₀₎ image signal) including signals corresponding to the center wavelength of the first narrowband light of 470 nm and the center wavelength of the second narrowband light of 440 nm is oxygen It is highly dependent not only on saturation but also on blood volume. Therefore, in addition to the B1 ₍₄₇₀₎ image signal and the B1 ₍₄₄₀₎ image signal, the signal ratios R2 / G2 and R3 / G3 corresponding to the light that changes mainly depending on the blood volume are used to depend on the blood volume. And the oxygen saturation can be determined accurately.

The oxygen saturation calculation unit 83 refers to the A mode table 82a or the B mode table 82b stored in the correlation storage unit 82 depending on whether the special observation mode is executed in the A mode or the B mode. Then, the oxygen saturation corresponding to the signal ratio calculated by the signal ratio calculation unit 81 is calculated for each pixel. When the special observation mode is executed in the A mode, the oxygen saturation calculation unit 83 refers to the A mode table 82a to calculate the oxygen saturation (A processing mode), and the special observation mode is executed in the B mode. If so, the oxygen saturation is calculated with reference to the B mode table 82b (B processing mode). Specifically, in the A processing mode, when the signal ratio B1 ₍₄₇₀₎ / G2 and the signal ratio R2 / G2 at a predetermined pixel are B1 ₍₄₇₀₎ ^* / G2 ^* and R2 ^* / G2 ^* , respectively, FIG. As shown in the figure, referring to the A mode table 82a, the oxygen saturation corresponding to the signal ratio B1 ₍₄₇₀₎ ^* / G2 ^* and the signal ratio R2 ^* / G2 ^* is “60%”. Therefore, the oxygen saturation calculation unit 83 calculates the oxygen saturation of this pixel as “60%”. The B processing mode is the same as that in the A mode except that the table to be referenced is the B mode table 82b.

For example, in the A processing mode, the signal ratio B1 ₍₄₇₀₎ / G2 and the signal ratio R2 / G2 are hardly increased or decreased extremely. That is, the values of the signal ratio B1 ₍₄₇₀₎ / G2 and the signal ratio R2 / G2 are above the lower limit line 93 with an oxygen saturation of 0%, and conversely below the upper limit line 94 with an oxygen saturation of 100%. rare. However, when the calculated oxygen saturation falls below the lower limit line 93, the oxygen saturation calculation unit 83 sets the oxygen saturation to 0%. When the calculated oxygen saturation exceeds the upper limit line 94, the oxygen saturation is set to 100. %. In addition, when the points corresponding to the signal ratio B1 ₍₄₇₀₎ / G2 and the signal ratio R2 / G2 deviate from between the lower limit line 93 and the upper limit line 94, the reliability of oxygen saturation in the pixel may be low. It is possible to make the display so that it can be understood or not calculate the oxygen saturation. The same applies to the B mode.

  The image generation unit 84 uses the oxygen saturation calculated by the oxygen saturation calculation unit 86 and the image signals of RGB colors obtained by imaging with white light to form an oxygen saturation image obtained by imaging oxygen saturation. Is generated. Specifically, when the special observation mode is executed in the A mode, the image generation unit 84 applies a gain corresponding to the oxygen saturation to the B2 image signal, the G2 image signal, and the R2 image signal of the second frame. RGB image data is generated using a B2 image signal, a G2 image signal, and an R2 image signal applied to each pixel and gained. For example, the image generation unit 84 multiplies all of the B2 image signals by the same gain “1” for pixels having oxygen saturation of 60% or more. On the other hand, for pixels with oxygen saturation less than 60%, the B2 image signal is multiplied by a gain less than “1”, and the G2 image signal and the R2 image signal are multiplied by a gain of “1” or more. . The RGB image data generated using the B1 image signal, G2 image signal, and R2 image signal after the gain processing is an A-mode oxygen saturation image.

  When the special observation mode is executed in the B mode, the image generation unit 84 applies a gain corresponding to the oxygen saturation to the B3 image signal, the G3 image signal, and the R3 image signal in the third frame for each pixel. RGB image data is generated using the B3 image signal, the G3 image signal, and the R3 image signal that have been applied and gained. The gain is applied in the same manner as in the A mode, and the RGB image data generated using the B3 image signal, G3 image signal, and R3 image signal after gain processing is an oxygen saturation image in the B mode.

  The oxygen saturation image generated by the image generation unit 84 is expressed in the same color as the normal observation image in a high oxygen region (region where the oxygen saturation is 60 to 100%). On the other hand, a low oxygen region where the oxygen saturation is lower than a predetermined value (region where the oxygen saturation is 0 to 60%) is represented by a color (pseudo color) different from that of the normal observation image.

  In the present embodiment, the image generation unit 84 multiplies the gain for pseudo-coloring only the low oxygen region, but the gain corresponding to the oxygen saturation is applied even in the high oxygen region, and the entire oxygen saturation image is obtained. A pseudo color may be used. Further, although the low oxygen region and the high oxygen region are separated by oxygen saturation 60%, this boundary is also arbitrary.

  Next, the flow of observation by the endoscope system 10 of this embodiment will be described along the flowchart of FIG. First, in the normal observation mode, screening is performed from the farthest view state (S10). In the normal observation mode, a normal observation image is displayed on the monitor 18. At the time of this screening, if a site (hereinafter, referred to as a possible lesion) such as a brownish area or redness is found (S11), the mode switching SW 22b is operated to switch to the special observation mode. (S12). Then, in this special observation mode, a diagnosis is made as to whether or not the likely lesion site is in a hypoxic state.

In the special observation mode, it is automatically executed in one of two types of sub-modes, A mode and B mode, depending on whether the zoom operation unit 22c is operated and magnified observation is performed (S13). First, when non-magnifying observation is performed with the zoom lens 47 at the telephoto end without operating the zoom operation unit 22c, the A mode filter 32a of the rotation filter 32 is arranged on the optical path of white light emitted from the broadband light source 31. Therefore, in synchronization with the frame rate of the image sensor 48 (S14), the first narrowband light having the center wavelength of 470 nm and the white light are alternately irradiated on the specimen. By imaging the specimen under each of these lights, a B1 ₍₄₇₀₎ image signal is acquired in the first frame, and a B2 image signal, a G2 image signal, and an R2 image signal are acquired in the second frame. (S15).

Then, among these image _{signals, B1 (470)} the signal ratio _{B1 (470)} of the image signal and the G2 image signal / G2 and oxygen saturation based on the signal ratio R2 / G2 of the R2 image signal and G2 image signals The degree is calculated (S16). Thereafter, RGB image data is generated using the B2 image signal, the G2 image signal, and the R2 image signal multiplied by the gain corresponding to the calculated oxygen saturation, whereby the oxygen saturation in which the low oxygen region is displayed in a pseudo color. An image is generated (S17) and displayed on the monitor 18 (S18).

  Then, based on the non-enlarged oxygen saturation image displayed on the monitor 18, the doctor confirms whether or not the lesion possibility site is in a hypoxic state. Such display of the oxygen saturation is continuously performed until the normal observation mode is switched (S25). When the diagnosis is finished, the insertion portion 21 of the endoscope 12 is extracted from the sample (S26).

On the other hand, as shown in FIG. 14, when an oxygen saturation image 91 generated and displayed at the time of non-magnifying observation is displayed as a hypoxic region 92 in which a lesion possibility site is pseudo-colored, a doctor is discovered. The low oxygen region 92 is enlarged and observed by operating the zoom operation 22c. When the operation of the zoom operation unit 22c is detected by the zoom detection unit 67a (S13), the control unit 67 switches the light emission mode of the light source device 14 to the B light emission mode. That is, the filter control unit 33 arranges the B mode filter 32b of the rotary filter 32 on the optical path of white light emitted from the broadband light source 31 (S20). When magnified observation is detected and the sub-mode of the special observation mode is switched from the A mode to the B mode, the second narrowband light having the center wavelength of 440 nm, the third narrowband light having the center wavelength of 450 nm, and the white light are Irradiation is sequentially performed in synchronization with the frame rate of the image sensor 48. Therefore, a B1 ₍₄₄₀₎ image signal is acquired in the first frame, a B2 ₍₄₅₀₎ image signal is acquired in the second frame, and a B3 image signal, a G3 image signal, and an R3 image signal are acquired in the third frame. Obtained (S21).

Among these image signals, the signal ratio B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ of the B1 ₍₄₄₀₎ image signal and the B2 ₍₄₅₀₎ image signal, and the signal ratio R3 / G3 of the R3 image signal and the G3 image signal. Based on the above, the oxygen saturation is calculated (S22). Thereafter, RGB image data is generated using the B3 image signal, the G3 image signal, and the R3 image signal multiplied by the gain corresponding to the calculated oxygen saturation, whereby the oxygen saturation in which the hypoxic region is displayed in a pseudo color. An image is generated (S23) and displayed on the monitor 18 (S24).

At the time of magnified observation, for example, using the first narrowband light of A mode, the oxygen saturation is calculated based on the B1 ₍₄₇₀₎ image signal by the first narrowband light and the G2 image signal by the green wavelength band light in the white light. When the oxygen saturation image 93 is generated by calculation, an artifact 94 appears in the oxygen saturation image 93 reflecting the distribution of the amount of light of each light (see FIG. 14). For this reason, by carrying out magnified observation, an inaccurate oxygen saturation is displayed rather than being able to observe the hypoxic region 92 in detail.

On the other hand, in the B mode, the second narrowband light and the third narrowband light are used, and the signal ratio B1 _{(440 )} of the B1 ₍₄₄₀₎ image signal and the B2 ₍₄₅₀₎ image signal by these second and third narrowband lights. _{) Since} the oxygen saturation is calculated based on / B2 ₍₄₅₀₎ and the oxygen saturation image 96 is generated, no artifact 94 appears in the generated oxygen saturation image 96 (see FIG. 14). For this reason, the oxygen saturation image 96 generated and displayed in the B mode calculates an accurate oxygen saturation without being affected by the distribution of the amount of signal light, etc., even though the specimen is magnified. And the oxygen saturation of the hypoxic region 92 can be closely observed.

As described above, the artifact 94 is reduced in the B mode because the second and third narrowband lights are closer in center wavelength than the first narrowband light in the A mode and the green wavelength band in the white light. by. That is, even if different light intensity distributions are different between the second narrowband light and the third narrowband light by the enlarged observation, if the central wavelengths of the second and third narrowband lights are close, the respective light intensity distributions. The differences are small. For example, even if the light signal distribution of the second narrowband light and the third narrowband light changes to the image signal multiplied by the coefficients α ₂ and α ₃ , if the respective light amount distributions appearing are substantially equal (α ₂ ≈α ₃ ), and the signal ratio B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ for calculating the oxygen saturation is (α ₁ B1 ₍₄₄₀₎ ) / (α ₂ B2 ₍₄₅₀₎ ) ≈B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ , and the influence of the light amount distribution and the like is reduced. In the case of this embodiment, since the center wavelengths of the second narrowband light (440 nm) and the third narrowband light (450 nm) are particularly close, the artifact 94 can be suppressed. Of course, the artifact 94 can be reduced for the same reason when using broadband light or wavelength bands of other colors instead of the second and third narrowband lights.

  In the B mode, the zoom lens 47 is moved to the wide end by the operation of the zoom operation unit 22c, and is repeatedly performed until the magnification observation is finished (returning to the non-magnification observation) (S25).

  In the first embodiment, after the low oxygen region 92 is confirmed in the A mode at the time of non-magnification observation, the low oxygen region 92 is magnified, but the low oxygen region 92 is not detected at the time of non-magnification observation. In some cases, the zoom operation unit 22c is operated to switch to magnified observation. Also in this case, if the operation of the zoom operation unit 22c, that is, the shift to the enlarged observation is detected by the zoom detection unit 67a, the control unit 67 automatically switches to the B mode.

[Second Embodiment]
In the endoscope system 10 of the first embodiment, the zoom operation is monitored to switch between executing the special observation mode in the A mode or the B mode, but instead of monitoring the zoom operation. The A mode and the B mode may be switched by detecting the artifact 94 from the generated oxygen saturation image.

  In this case, as in the endoscope system 200 shown in FIG. 15, the control unit 67 is provided with an artifact detection unit 67b instead of the zoom detection unit 67a. Other configurations are the same as those of the endoscope system 10 of the first embodiment.

  The artifact detection unit 67b acquires the oxygen saturation image from the image generation unit 84, and detects the artifact 94 from the acquired oxygen saturation image. The artifact 94 that appears in the magnification observation is expressed in the structure of the endoscope 12 such as the arrangement of the illumination optical system 24a and the imaging optical system 24b in the distal end portion 24 (distribution, intensity, etc.), and the magnification rate of the specimen (or The distance between the tip 24 and the specimen) is almost determined. For this reason, the artifact detection unit 67b detects whether or not the artifact 94 appears by monitoring the pixel value at an arbitrary point or a plurality of points in the oxygen saturation image.

  For example, when monitoring a pixel at a position where an artifact appears to make it appear to be in a low oxygen state, the B pixel value is compared with a first threshold value, and the B pixel value is equal to or less than the first threshold value due to gain. If this is the case (if it is a hypoxia pseudo-color), the artifact 94 is detected. There may be a case where the sample itself is not an artifact 94 but a really hypoxic state in the pixel being monitored, but the artifact 94 is generally larger than the hypoxic state according to the properties of the sample, so the first threshold is increased to some extent. If set, the artifact 94 can be detected without erroneous detection.

  In addition, you may monitor the pixel of the position where it always appears in a high oxygen state when the artifact 94 appears. In addition, if the pixel values are monitored at a plurality of points, the detection accuracy is improved. Therefore, it is preferable to monitor the pixel values at two or more points. Furthermore, the detection method of the artifact 94 is arbitrary. Instead of comparing the pixel value with the threshold value, the artifact 94 may be detected by extracting the frequency component of the artifact 94.

  When the artifact 94 is not detected from the oxygen saturation image, the control unit 67 sets the light emission mode of the light source device 14 to the A light emission mode, and operates each unit of the oxygen saturation image generation unit 76 in the A processing mode. That is, if the artifact 94 is not detected, the endoscope system 200 operates in the A mode. On the other hand, when the artifact 94 is detected from the oxygen saturation image, the control unit 67 sets the light emission mode of the light source device 14 to the B light emission mode, and operates each unit of the oxygen saturation image generation unit 76 in the B processing mode. . That is, when the artifact 94 is detected, the endoscope system 200 operates in the B mode.

  As described above, when the artifact 94 is detected from the oxygen saturation image and the special observation mode is switched between the A mode and the B mode depending on whether the artifact 94 is detected, the endoscope 12 does not depend on the zoom operation. Even when close-up observation is performed with the distal end portion 24 close to the specimen, an oxygen saturation image without artifact 94 can be generated and displayed.

  Note that the first and second embodiments may be combined. Specifically, as in the first embodiment, when the zoom operation is monitored, artifacts are also detected and the zoom operation is performed, and it is predicted that the artifacts appear, or when the artifacts already appear In any case, the special observation mode may be executed in the B mode. As described above, according to the endoscope system in which the first and second embodiments are combined, the distal end portion 24 of the endoscope 12 is brought close to the specimen when performing magnified observation by the zoom operation and without performing the zoom operation. Thus, an accurate oxygen saturation image can be generated and displayed both in the case of magnifying observation.

  In the endoscope system 200 according to the second embodiment, the artifact detection unit 67b detects the artifact 94 from the oxygen saturation image, but the artifact 94 may be detected from the calculated oxygen saturation data.

  In the first and second embodiments, the mode switching SW 22b is for switching between the normal observation mode and the special observation mode, and the A mode and the B mode of the special observation mode depend on the presence or absence of zoom operation or artifacts. Although the automatic switching is automatically performed, the special observation mode may be manually switched between the A mode and the B mode by operating the mode switching SW 22b. In this case, the mode switching SW 22b functions as a light emission mode switching operation unit that switches the light emission mode of the light source device and a processing mode switching operation unit that switches the processing mode of each unit of the oxygen saturation image generation unit 76. In addition to the mode switching SW 22b, an operation unit such as a button or a switch for switching the special observation mode between the A mode and the B mode may be provided.

  In the first and second embodiments, the zoom operation and the artifact are detected, and the A mode and the B mode of the special observation mode are switched. However, the A mode and the B mode according to other than these (for example, the exposure amount). May be switched. Further, for example, as in the endoscope system 250 shown in FIG. 16, a distance measuring sensor 251 for measuring the distance between the distal end portion 24 and the sample is provided in the distal end portion 24, and the control unit 67 The light emission mode of the light source device 14 and the processing mode of each part of the oxygen saturation image generation unit 76 may be switched according to the distance between the tip 24 measured by the above and the specimen. This distance measuring sensor may be used by being inserted into a forceps channel.

  In the first and second embodiments, the table referred to by the oxygen saturation calculation unit 83 is switched between the A mode table 82a and the B mode table 82b in accordance with the switching between the A mode and the B mode. A predetermined function may be used instead of the table switching. For example, only the A mode table 82a is stored in the correlation storage unit 82, and in the case of the B mode, the oxygen saturation calculated with reference to the A mode table 82a is calculated using a function determined in advance through experiments or the like. The corrected oxygen saturation value may be used as the oxygen saturation in the B mode. Conversely, only the B mode table 82b may be stored in the correlation storage unit 82, and in the A mode, the oxygen saturation calculated using the B mode table 82b may be corrected with a predetermined function. In addition, the correlation storage unit 82 stores a function that associates the signal ratio calculated in each mode with the oxygen saturation instead of the A mode table 82a and the B mode table 82b, and oxygen saturation based on the function. The degree may be calculated.

[Third Embodiment]
In the first and second embodiments, the B-mode filter 42b uses the rotary filter 32 divided into three sections of the second narrowband light transmission part 34a, the third narrowband light transmission part 34b, and the opening 34c. Instead of the rotary filter 32, a rotary filter 301 shown in FIG.

  The rotary filter 301 has the same A mode filter 32a as the rotary filter 32 of 1st, 2nd embodiment in an inner peripheral part. On the other hand, a B-mode filter 301b provided on the outer periphery of the rotary filter 301 includes a second narrowband light transmitting section 304 that selectively transmits second narrowband light (440 ± 10 nm) having a center wavelength of 440 nm, and a bandpass. A filter 305 is provided. The characteristics of the second narrowband light transmission part 304 are the same as those of the second narrowband light transmission part 34a provided in the rotary filter 32 of the first and second embodiments. As shown in FIG. 18, the bandpass filter 305 transmits third narrowband light (450 ± 10 nm) having a center wavelength of 450 nm and green-red broadband light (for example, 530 to 700 nm).

As shown in FIG. 19, when the rotary filter 301 is used, in the B mode, the second narrowband light is irradiated in the first frame, and a B1 ₍₄₄₀₎ image signal is obtained. Further, in the second frame of the B mode, the third narrowband light and the green / red broadband light are irradiated simultaneously, so that B2 ₍₄₅₀₎ image signals, G2 image signals, and R2 image signals corresponding to these are obtained. Therefore, similarly to the endoscope systems 10 and 200 of the first and second embodiments, the signal ratio B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ between the B1 ₍₄₄₀₎ image signal and the B2 ₍₄₅₀₎ image signal, and R2 The oxygen saturation can be calculated based on the signal ratio R2 / G2 between the image signal and the G2 image signal. In this case, compared with the case where the rotary filter 32 of the first and second embodiments is used, the time required to generate one oxygen saturation image in the B mode is reduced from 3 frames to 2 frames. The oxygen saturation image can be quickly generated and displayed.

[Fourth Embodiment]
In the first to third embodiments, the first to third narrowband light and the white light are generated using the broadband light source 31 and the rotary filters 32 and 301, but instead of the broadband light source 31 and the rotary filters 32 and 301. Alternatively, an LED (Light Emitting Diode) light source may be used.

  For example, as illustrated in FIG. 20, the light source device 14 of the endoscope system 400 includes an LED light source unit 401 and a light source control unit 402. The configuration other than the light source device 14 is the same as that of the endoscope system 10 of the first embodiment.

  The LED light source unit 401 includes a white LED 403, a first narrow band LED 404, a second narrow band LED 405, and a third narrow band LED 406. The white LED 403 emits white light including blue, green, and red wavelength bands. The first narrowband LED 404 emits first narrowband light having a center wavelength of 470 nm (470 ± 10 nm), and the second narrowband LED 405 emits second narrowband light having a center wavelength of 440 nm (440 ± 10 nm). The third narrow band LED 406 emits third narrow band light having a center wavelength of 450 nm (450 ± 10 nm).

  The light source control unit 402 controls the timing of turning on (and turning off) the LEDs 403 to 406 of the LED light source unit 401, the amount of light emission, and the like based on the control signal input from the mode switching SW 22b or the control unit 67.

  Specifically, when the normal observation mode is set by the mode switching SW 22b, the light source control unit 402 turns on only the white LED 403 and turns off the first to third narrowband LEDs 404 to 406. For this reason, in the normal observation mode, white light emitted from the white LED 403 enters the light guide 41 and irradiates the specimen. Therefore, in the normal observation mode of the endoscope system 400, the B image signal, the G image signal, and the R image signal are obtained for each frame, as in the normal mode of the first embodiment (see FIG. 5). The normal observation image is generated by using this.

In addition, when the special observation mode is set by the mode switching SW 22b, when the control signal indicating that the special observation mode is executed in the A mode is input from the control unit 67, the light source control unit 402 causes the first narrowband. The LED 404 and the white LED 403 are alternately turned on every frame. In the frame in which the first narrow band LED 404 is turned on, the white LED 403 and the second and third narrow band LEDs 405 and 406 are turned off, and in the frame in which the white LED 403 is turned on, the first to third narrow band LEDs 404 to 406 are turned off. Let For this reason, the first narrowband light is irradiated to the specimen in the first frame, and white light is irradiated to the second frame. Therefore, when the endoscope system 400 executes the special observation mode in the A mode, the B1 ₍₄₇₀₎ image signal is obtained in the first frame as in the A mode (see FIG. 6) of the first embodiment. In the second frame, a B2 image signal, a G2 image signal, and an R2 image signal are obtained. The oxygen saturation calculation method using these image signals and the oxygen saturation image generation method are the same as those in the first embodiment.

When a control signal indicating that the special observation mode is executed in the B mode is input from the control unit 67, the light source control unit 402 sequentially turns the second narrowband LED 405, the third narrowband LED 406, and the white LED 403 for each frame. Light up. In each frame, the other LEDs are turned off. Therefore, the second narrowband light is irradiated to the first frame, the third narrowband light is irradiated to the second frame, and the white light is irradiated to the third frame. Therefore, when the endoscope system 400 executes the special observation mode in the B mode, as in the B mode (see FIG. 7) of the first embodiment, the B1 ₍₄₄₀₎ image signal is 2 frames in the first frame. A B2 ₍₄₅₀₎ image signal is obtained for the eyes, and a B3 image signal, a G3 image signal, and an R3 image signal are obtained for the third frame. The oxygen saturation calculation method using these image signals and the oxygen saturation image generation method are the same as those in the first embodiment.

  Note that the endoscope system 400 according to the fourth embodiment includes a zoom detection unit 67a in the control unit 67 as in the endoscope system 10 according to the first embodiment, detects a zoom operation, and executes the special observation mode. Although the mode is switched to the B mode, the execution mode of the special observation mode may be switched by detecting an artifact as in the endoscope system 200 of the second embodiment.

[Fifth Embodiment]
In the fourth embodiment, an LED light source is used instead of the broadband light source 31 and the rotary filters 32 and 301 of the first to third embodiments, but a laser diode (LD) may be used instead of the rotary filter 32. .

  For example, as illustrated in FIG. 21, the light source device 14 of the endoscope system 500 includes an LD unit 501 and a light source control unit 502. Further, the illumination optical system 24a includes a phosphor 503. Other than that, it is the same as the endoscope system 10 of the first embodiment.

  The LD unit 501 includes a first LD 504, a second LD 505, and a third LD 506 as a light source. The first LD 504 emits first blue laser light having a center wavelength of 470 nm (470 ± 10 nm). The second LD 505 emits second blue laser light having a center wavelength of 440 nm (440 ± 10 nm). The third LD 506 emits third blue laser light having a center wavelength of 450 nm (450 ± 10 nm). Each of these LDs 504 to 506 can use a broad area type InGaN laser diode, and can also use an InGaNAs laser diode or a GaNAs laser diode. Further, a light emitter such as a light emitting diode may be used as the light source.

  The light emission timing, the light emission amount, and the like of each of the LDs 504 to 506 are individually controlled by the light source control unit 502. The light source control unit 502 controls the light emission timings of the LDs 504 to 506 based on control signals input from the mode switching SW 22 b and the control unit 67. In the normal observation mode, the light source control unit 502 causes the first LD 504 to emit the first blue laser light, and the second LD 505 and the third LD 506 are turned off. When executing the special observation mode in the A mode, the light source control unit 502 emits the first blue laser light from the first LD 504 as in the normal observation mode. On the other hand, when the special observation mode is executed in the B mode, the light source control unit 502 causes the second LD 505 and the third LD 506 to alternately emit the second blue laser light and the third blue laser light for each frame.

  Blue laser light emitted from the LDs 504 to 506 is incident on the phosphor 503 through an optical member (all not shown) such as a condenser lens, an optical fiber, and a multiplexer, and the light guide 41. The phosphor 503 excites and emits green to red fluorescence when the first to third blue laser beams are incident thereon. Further, part of the first to third blue laser beams incident on the phosphor 503 passes through the phosphor 503. For this reason, the specimen is irradiated with white light composed of any one of the first to third blue laser beams transmitted through the phosphor 503 and green to red fluorescence emitted from the phosphor 503.

  As shown in FIG. 22, when the first blue laser light is incident on the phosphor 503, the sample is irradiated with the first white light 510. The first white light is composed of first narrowband light 510a and first fluorescence 510b. The first narrow band light 510a is a component in which the first blue laser light is transmitted through the phosphor 503, and the first fluorescence 510b is fluorescence emitted from the phosphor 503 by the first blue laser light.

  When the second blue laser light is incident on the phosphor 503, the specimen is irradiated with the second white light 511. The second white light is composed of second narrowband light 511a and second fluorescence 511b. The second narrow band light 511a is a component in which the second blue laser light is transmitted through the phosphor 503, and the second fluorescence 511b is fluorescence emitted from the phosphor 503 by the second blue laser light.

  Similarly, when the third blue laser light is incident on the phosphor 503, the specimen is irradiated with the third white light 512. The third white light 512 includes a third narrow-band light 512a that is a transmission component of the third blue laser light, and a third fluorescence 512b that is excited and emitted by the third blue laser light.

The components of the phosphor 503 are adjusted so that the spectral shapes of the respective fluorescences 510b to 512b included in the first to third white lights 510 to 512 are substantially equal. Such a phosphor 503 can be formed of, for example, a YAG phosphor or BAM (BaMgAl ₁₀ O ₁₇ ).

As shown in FIG. 23, in the normal observation mode, the first white light 510 is irradiated on the specimen. In this case, part of the blue components of the first narrowband light 510a and the first fluorescence 510b is incident on the B pixel of the image sensor 48. Since the first narrowband light 510a has a light intensity much higher than the blue component of the first fluorescence 510b, the B image signal output from the B pixel is substantially due to the reflected light of the first narrowband light 510a. Further, the green wavelength band component and the red wavelength band component of the broadband first fluorescence 510b are incident on the G pixel and the R pixel of the image sensor 48, respectively. Therefore, in the normal observation mode of the endoscope system 505, a B1 ₍₄₇₀₎ image signal, a G1 image signal, and an R1 image signal are obtained for each frame, and a normal observation image is generated and displayed using these.

When the special observation mode is executed in the A mode, the sample is irradiated with the first white light 510 as in the normal observation mode. However, when the special observation mode is executed in the A mode, the signal ratio B1 ₍₄₇₀₎ / G1 and the signal ratio are obtained using the B1 ₍₄₇₀₎ image signal, the G1 image signal, and the R1 image signal obtained from the image sensor 48. The oxygen saturation is calculated based on R1 / G1. As the A mode table used at this time, the A mode table 82a of the first embodiment can be used as it is. Then, an oxygen saturation image is generated by multiplying the B1 ₍₄₇₀₎ image signal, the G1 image signal, and the R1 image signal by a gain corresponding to the oxygen saturation.

On the other hand, as shown in FIG. 24, when the special observation mode is executed in the B mode, the specimen is alternately irradiated with the second white light 511 and the third white light 512 for each frame. The B image signal when the second white light 511 is irradiated is substantially the same as the B image signal when the first white light 510 is irradiated, and the B image signal is substantially the second reflected light of the first narrowband light 510a. This is due to the reflected light of the narrow band light 511a, and the B image signal when the third white light 512 is irradiated is substantially due to the reflected light of the third narrow band light 512a. Therefore, the B1 ₍₄₄₀₎ image signal, the G1 image signal, and the R1 image signal are obtained in the first frame of the B mode, and the B2 ₍₄₅₀₎ image signal, the G2 image signal, and the R2 image signal are obtained in the second frame. It is done. The oxygen saturation can be calculated using the B mode table 82b of the first embodiment based on the signal ratio B1 ₍₄₄₀₎ / B2 ₍₄₅₀₎ and, for example, the signal ratio R2 / G2. For example, the oxygen saturation image can be generated by multiplying the B2 ₍₄₅₀₎ image signal, the G2 image signal, and the R2 image signal in the second frame by a gain corresponding to the oxygen saturation.

  In the first to fifth embodiments, when the special observation mode is executed in the B mode, the signal ratio between the B image signal obtained by the second narrowband light and the B image signal obtained by the third narrowband light. Is used to calculate the oxygen saturation, but the oxygen saturation may be calculated based on the signal ratio obtained by the B image signal obtained by the first narrowband light and the third narrowband light. The oxygen saturation may be calculated based on the signal ratio between the B image signal obtained from the first narrowband light and the B image signal obtained from the second narrowband light.

In the first to fifth embodiments, narrowband light of 440 ± 10 nm and 450 ± 10 nm is used as the first and second signal light for B mode, respectively. However, the center wavelengths λ _B1 (440 nm) are used. ), Λ _B2 (450 nm) is only an example. For example, the first signal light for B mode preferably has a center wavelength of 445 nm (wavelength band is 445 ± 10 nm).

  In the first to fifth embodiments, narrowband light in the blue wavelength band is used to calculate the oxygen saturation, but narrowband light in the green wavelength band and red wavelength band may be used. For example, as the first signal light for B mode and the second signal light for B mode, both narrow band light in the green wavelength band may be used. In addition, broadband light may be used as long as the amount of light absorbed by oxyhemoglobin and deoxyhemoglobin can be detected.

  In the first to fifth embodiments, the oxygen saturation is calculated based on the signal ratio reflecting the blood volume (for example, the signal ratio R2 / G2). A saturation value may be calculated.

  In the first to fifth embodiments, an oxygen saturation image obtained by imaging oxygen saturation is generated and displayed. In addition, a blood volume image obtained by imaging blood volume is generated and displayed. May be. Since the blood volume has a correlation with the signal ratio between the R image signal and the G image signal (for example, the signal ratio R2 / G2), the blood volume image obtained by imaging the blood volume by assigning a different color according to the signal ratio. Can be created.

  In the first to fifth embodiments, the oxygen saturation is calculated, but instead of or in addition to this, “blood volume (signal ratio R2 / G2) × oxygen saturation (%)”. Other biological function information such as an oxyhemoglobin index obtained or a reduced hemoglobin index obtained from “blood volume × (1−oxygen saturation) (%)” may be calculated.

10, 200, 250, 400, 500 Endoscope system 12 Endoscope 14 Light source device 16 Processor device 18 Monitor 31 Broadband light source 32, 301 Rotating filter 33 Filter control unit 67 Control unit 67a Zoom detection unit 67b Artifact detection unit 91, 93,96 Oxygen saturation image 92 Hypoxic region

Claims (17)

And A light-emitting pattern of irradiation center wavelength lambda _A1 of the signal light _{L A2} of the signal light _{L A1} and the center wavelength lambda _A2 to sample each signal light _{L B2} of the signal light _{L B1} and the center wavelength lambda _B2 of the central wavelength lambda _B1 Each of the central wavelengths λ _A1 , λ _A2 , λ _B1 , and λ _B2 can emit signal light with the B light emission pattern that irradiates the specimen, and | λ _A1 −λ _A2 |> | λ _B1 −λ _B2 | A light source device satisfying
An image sensor that images the specimen with each reflected light of the signal lights L _A1 , L _A2 , L _B1 , and L _B2 and outputs an image signal;
When the light emission pattern of the light source device is the A light emission pattern, for each pixel based on the ratio of each image signal of the same pixel obtained by the reflected light of the signal light L _A1 and the signal light L _A2 When oxygen saturation is calculated and the light emission pattern of the light source device is the B light emission pattern, the ratio of the image signals of the same pixel obtained by the reflected light of the signal light L _B1 and the signal light L _B2 An oxygen saturation calculator for calculating oxygen saturation for each pixel based on
A controller that switches a light emission pattern of the light source device between the A light emission pattern and the B light emission pattern;
An endoscope system comprising: An A mode table representing the correlation between the ratio of each image signal obtained by the reflected light of the signal light L _A1 and the reflected light of the signal light L _A2 and oxygen saturation, the signal light L _B1 and the signal light L _B2 A correlation storage unit that stores a ratio of each image signal obtained by the reflected light of B and a B-mode table representing a correlation between oxygen saturation levels,
When the light emission pattern of the light source device is the A light emission pattern, the oxygen saturation calculation unit calculates the oxygen saturation using the A mode table, and when the light emission pattern of the light source device is the B light emission pattern The endoscope system according to claim 1, wherein oxygen saturation is calculated using the B-mode table. A zoom lens for enlarging or reducing the image of the specimen formed on the image sensor;
A zoom detection unit for monitoring the operation of the zoom lens,
The endoscope system according to claim 1, wherein the control unit switches between the A light emission mode and the B light emission mode according to a detection result by the zoom detection unit.   When performing non-magnification observation in which the image of the specimen is most reduced by the zoom lens, the control unit changes the light emission pattern of the light source device to the A light emission pattern, and the image of the specimen is enlarged by the zoom lens. The endoscope system according to claim 3, wherein when performing magnified observation, the light emission pattern of the light source device is changed to the B light emission pattern. An artifact detection unit that detects an artifact that is an error in the oxygen saturation regardless of the nature of the specimen;
The control unit sets the light emission mode of the light source device to the A light emission mode when the artifact detection unit does not detect the artifact, and sets the light emission mode of the light source device when the artifact detection unit detects the artifact. The endoscope system according to claim 1 or 2, wherein the B light emission mode is set. A light emission mode switching operation section for manually switching the light emission mode of the light source device;
The endoscope system according to claim 1, wherein the control unit switches a light emission mode of the light source device between the A light emission mode and the B light emission mode based on an operation of the light emission mode switching operation unit. A distance measuring sensor that measures the distance between the distal end of the endoscope on which the image sensor is mounted and the sample;
The said control part switches the light emission mode of the said light source device with the said A light emission mode and the said B light emission mode according to the distance of the said front-end | tip part measured by the said ranging sensor and the said sample. The endoscope system described. The endoscope system according to any one of claims 1 to 7, wherein the signal light L _B1 is narrowband light. The endoscope system according to any one of claims 1 to 8, wherein the signal light _LB2 is narrowband light. The endoscope system according to any one of claims 1 to 9, wherein the center wavelengths λ _B1 and λ _B2 of the signal light L _B1 and the signal light L _B2 belong to a wavelength band of the same color. The endoscope system according to claim 10, wherein each of the center wavelengths λ _B1 and λ _B2 of the signal light L _B1 and the signal light L _B1 belongs to a blue wavelength band. The endoscope system according to any one of claims 1 to 11, wherein the center wavelength λ _B2 of the signal light L _B2 is a wavelength at an isosbestic point where the absorption coefficients of oxyhemoglobin and reduced hemoglobin are equal. The signal light _{L A1} having a wavelength band _{W A1,} and A light-emitting pattern which irradiates the signal light _{L A2} to sample each having a wavelength band _{W A2,} the signal light _{L B1} having a wavelength band _{W B1,} the wavelength band _{W B2} The signal light can be emitted by the B light emission pattern for irradiating the specimen with the signal light L _B2 having the above, and the absorption coefficient of hemoglobin is integrated in each of the wavelength bands W _A1 , W _A2 , W _B1 , and W _B2 . When the values are S _A1 , S _A2 , S _B1 , and S _B2 , each of the wavelength bands WA ₁ , WA ₂ , W _B1 , and W _B2 is | S _A1 −S _A2 | >> | S _B1 −S _B2 | A light source device that is defined to satisfy,
An image sensor that images the specimen with each reflected light of the signal lights L _A1 , L _A2 , L _B1 , and L _B2 and outputs an image signal;
In the case of the A emission pattern, oxygen saturation is calculated based on the ratio of each image signal obtained by the reflected light of the signal light L _A1 and the signal light L _A2 for each pixel of the image sensor, In the case of the B emission pattern, the oxygen saturation is calculated for each pixel of the image sensor based on the ratio of each image signal obtained by the reflected light of the signal light L _B1 and the signal light L _B2. A calculation unit;
A controller that switches a light emission pattern of the light source device between the A light emission pattern and the B light emission pattern;
An endoscope system comprising: B illumination pattern emitted and A emitting pattern which emits signal light _{L A2} of the signal having a center wavelength lambda _A1 light _{L A1} and the center wavelength lambda _A2, the signal light _{L B2} of the signal light _{L B1} and the center wavelength lambda _B2 of the central wavelength lambda _B1 And a light source device that satisfies | λ _A1 −λ _A2 |> | λ _B1 −λ _B2 | with respect to each of the center wavelengths λ _A1 , λ _A2 , λ _B1 , and λ _B2 , and each of the signals When the specimen is imaged with each reflected light of light L _A1 , L _A2 , L _B1 , L _B2 and an image signal is output, and the light emission pattern of the light source device is the A light emission pattern, The oxygen saturation is calculated for each pixel based on the ratio of the image signals of the same pixel obtained by the reflected light of the signal light L _A1 and the signal light L _A2 , and the light emission pattern of the light source device is the B light emission pattern. In the case of An endoscope comprising an oxygen saturation calculating unit for calculating oxygen saturation for each of the pixels based on the ratio of the image signals of the same pixel obtained by the reflected light of the light L _B1 and the signal light L _B2, the In the method of operating the system,
An operating method of an endoscope system comprising a first light emission pattern switching step of switching a light emission pattern of the light source device from the A light emission pattern to the B light emission pattern.   The operation method of the endoscope system according to claim 14, further comprising a second light emission pattern switching step of switching the light emission pattern of the light source device from the B light emission pattern to the A light emission pattern. And A light-emitting pattern of irradiation center wavelength lambda _A1 of the signal light _{L A2} of the signal light _{L A1} and the center wavelength lambda _A2 to sample each signal light _{L B2} of the signal light _{L B1} and the center wavelength lambda _B2 of the central wavelength lambda _B1 Each of the central wavelengths λ _A1 , λ _A2 , λ _B1 , and λ _B2 can emit signal light with the B light emission pattern that irradiates the specimen, and | λ _A1 −λ _A2 |> | λ _B1 −λ _B2 | A light source device that satisfies the requirements. B illumination pattern emitted and A emitting pattern which emits signal light _{L A2} of the signal having a center wavelength lambda _A1 light _{L A1} and the center wavelength lambda _A2, the signal light _{L B2} of the signal light _{L B1} and the center wavelength lambda _B2 of the central wavelength lambda _B1 And a light source device that satisfies | λ _A1 −λ _A2 |> | λ _B1 −λ _B2 | with respect to each of the center wavelengths λ _A1 , λ _A2 , λ _B1 , and λ _B2 , and each of the signals In a processor apparatus of an endoscope system, comprising: an image sensor that images the specimen with each reflected light of light L _A1 , L _A2 , L _B1 , and L _B2 and outputs an image signal;
When the light emission pattern of the light source device is the A light emission pattern, for each pixel based on the ratio of each image signal of the same pixel obtained by the reflected light of the signal light L _A1 and the signal light L _A2 When oxygen saturation is calculated and the light emission pattern of the light source device is the B light emission pattern, the ratio of the image signals of the same pixel obtained by the reflected light of the signal light L _B1 and the signal light L _B2 A processor device comprising an oxygen saturation calculation unit for calculating oxygen saturation for each pixel based on the above.

Images