WO2022202051A1 - Biological observation system, biological observation method, and irradiation device - Google Patents

Abstract

[Problem] To provide a biological observation system, a biological observation method, and an irradiation device with which information on deeper parts of a living body can be obtained. [Solution] According to the present disclosure, a biological observation system comprises: an irradiation unit that irradiates an observation site of a living body with coherent light through a diaphragm having a light-blocking portion that blocks light and an opening that transmits light; a pixel signal acquisition unit that acquires a pixel signal including a region of the observation site irradiated with the coherent light; and an image generation unit that generates a first image on the basis of a pixel signal of a dark region in the pixel signal, wherein the dark region is not irradiated with the coherent light.

Description

Living body observation system, living body observation method, and irradiation device

The present disclosure relates to a living body observation system, a living body observation method, and an irradiation device.

Conventionally, techniques have been developed for observing biological tissues, etc. by irradiating them with laser light and detecting speckle patterns. Observation of living tissue based on such speckle patterns is expected to be applied in various scenes such as surgical operation and medical diagnosis, and a technique capable of exhibiting high accuracy is required.

Japanese Patent Application Publication No. 2016-509509

However, when irradiating a biological tissue or the like with a laser beam, the reflected light from the surface of the biological body becomes strong. For this reason, there is a possibility that observation of the underlying tissue may become difficult.

Therefore, the present disclosure provides a living body observation system, a living body observation method, and an irradiation device capable of acquiring information on deeper parts of a living body.

In order to solve the above problems, according to the present disclosure, an irradiation unit that irradiates an observation site of a living body with coherent light through a diaphragm having a light shielding portion that shields light and an opening that transmits light;
a pixel signal acquisition unit that acquires pixel signals including a region of the observation site irradiated with the coherent light;
an image generating unit that generates a first image based on pixel signals in a dark area not irradiated with the coherent light in the pixel signals;
A living body observation system is provided, comprising:

The light shielding part may be made of a metal that does not transmit light.

The pixel signals of the dark region may be based on light that is part of the coherent light that is directly applied to the living body and is scattered by blood flow under the tissue of the observation site.

Further comprising a pixel range setting unit for setting a predetermined pixel value range based on a profile, which is a pixel row with respect to a positional change on the image based on the pixel signal,
The image generator may generate the first image based on the predetermined pixel value range.

It may further include an image generation unit that generates a second image based on pixel signals in the bright area irradiated with the coherent light.

A speckle calculator that calculates speckle data based on at least one of the first image and the second image may be further provided.

The speckle data includes speckle contrast,
The speckle calculator may generate an observation image based on the speckle contrast.

The pixel signal acquisition unit acquires a plurality of pixel signals obtained by changing the region of the observation site irradiated with the coherent light,
The first image generator may generate the first image based on the plurality of pixel signals.

The apparatus may further include an irradiation control unit that controls the irradiation intensity of the coherent light based on the speckle contrast value in the observation image.

The irradiation control unit may control the irradiation intensity of the coherent light based on pixel values of at least one of the dark region and the bright region in the pixel signal.

The aperture is a variable aperture, and further includes an aperture control unit that sets a width of an aperture and a width between apertures based on pixel values in the dark region and the bright region in the pixel signal. may

The aperture control unit may set the width between the openings so that a ratio of predetermined pixel values in the dark area and the bright area is within a predetermined range.

A blood flow meter device using the biological observation system may be used.

A microscope device using the biological observation system may be used.

A midoscope device using the living body observation system may be used.

In order to solve the above problems, according to the present disclosure, an irradiation step of irradiating an observation site of a living body with coherent light through a diaphragm having a light shielding portion for shielding light and an opening for transmitting light;
a pixel signal acquiring step of acquiring a pixel signal including a region of the observation site irradiated with the coherent light;
a first image generating step of generating a first image based on the pixel signals in the dark area not irradiated with the coherent light in the pixel signals;
A living body observation method is provided.

In order to solve the above problems, according to the present disclosure, a light source that generates coherent light;
A movable diaphragm having a light shielding portion that shields the coherent light and an opening that transmits the light,
The width of the light shielding portion and the width of the opening are determined based on pixel signals of a dark region not directly irradiated with the coherent light in an image including the region of the observation site in the living body irradiated with the coherent light. An illumination device is provided, at least one of which is controlled.

1 is a block diagram showing a configuration example of an observation system according to an embodiment of the present technology; FIG. FIG. 4 is a diagram showing a configuration example of a laser irradiation unit; Top view of the aperture. FIG. 4 is a schematic diagram showing the distribution of laser light on the exit-side surface of the diaphragm; FIG. 2 is a block diagram showing the configuration of an irradiation control unit; FIG. 4 is a diagram showing the relationship between the speckle contrast and the average luminance value of pixel signals; FIG. 2 is a block diagram showing the configuration of an arithmetic processing unit; FIG. 4 is a diagram showing an example of a pixel value profile generated by a profile generator; FIG. 4 is a diagram schematically showing laser light in a direct region and reflected and scattered light; FIG. 4 is a diagram schematically showing laser light in a global area and reflected and scattered light; FIG. 4 is a diagram schematically showing a processing example of a pixel value range generation unit; FIG. 4 is a diagram showing a correspondence relationship between an extracted pixel value range and a two-dimensional image acquired by an image acquiring unit; FIG. 5 is a diagram showing an example of an image generated by the first image generation unit based on the extracted pixel value range; FIG. 10 is a diagram showing an example of a D (direct image) image generated by a second image generation unit; FIG. 4 is a diagram schematically showing brightness values of pixels 43 included in a 3×3 cell 42 by light and shade; FIG. 4 is a schematic diagram for explaining a calculation example of speckle contrast within an effective area; FIG. 4 is a diagram for explaining the characteristics of a speckle pattern; The figure which shows the structural example of the laser irradiation part of a comparative example. FIG. 4 shows a G (global) image of a comparative example and a G (global) image according to the present disclosure; 4 is a flowchart showing an example of processing of the observation system; FIG. 10 is a side cross-sectional view of a diaphragm according to a second embodiment; The block diagram of the irradiation control part which concerns on 2nd Embodiment. 4A and 4B are diagrams for explaining a control example of a diaphragm control unit; FIG. FIG. 4 is another diagram for explaining a control example of the aperture control unit; FIG. 7 is a diagram for explaining still another control example of the aperture control unit; 5 is a flow chart showing an example of processing by an aperture control unit;

(First embodiment)
[Biological observation system]
FIG. 1 is a block diagram showing a configuration example of a biological observation system according to an embodiment of the present technology. The living body observation system 100 is used, for example, for observation of an operating field in surgery, observation of the inside of a patient's body in medical diagnosis, and the like. More specifically, the living body observation system 100 is used for a blood flow meter device, a microscope device, an endoscope device, and the like. In addition, the present technology can be applied when observing any living tissue.

This biological observation system 100 includes a laser irradiation unit 10, a camera 20, and a controller 30.

The laser irradiation unit 10 is arranged to face the observed region 2 of the patient, and irradiates the observed region 2 with laser light 11, which is coherent light. FIG. 1 schematically shows a laser beam 11 irradiated toward a patient's hand (observation site 2). The observation site 2 corresponds to a living tissue in this embodiment. Also, the laser irradiation unit 10 according to the present embodiment corresponds to the irradiation device.

A configuration example of the laser irradiation unit 10 will be described based on FIGS. 2A, 2B, and 3. FIG. FIG. 2A is a diagram showing a configuration example of the laser irradiation unit 10. As shown in FIG. FIG. 2B is a top view of the diaphragm 102. FIG.

As shown in FIG. 2A, the laser irradiation unit 10 has a laser 90 and a diaphragm 102. A laser 90 emits highly coherent light through an illumination optical system. As shown in FIG. 2B, the diaphragm 102 has a light blocking portion 102a and a slit-shaped opening 102b. The light blocking portion 102a is made of metal, for example, and does not transmit light. On the other hand, the opening 102b is configured to transmit light.

FIG. 3 is a schematic diagram showing the distribution of the laser light 11 on the surface of the aperture 102 on the exit side. The vertical axis indicates brightness, and the horizontal axis corresponds to the position of a line that crosses the diaphragm 102. FIG. Thus, the light intensity of the light shielding portion 102a of the diaphragm 102 can be regarded as 0 except for the boundary portion of the aperture. As a result, as shown in FIG. 2A, a striped projected optical image of bright portions, dark portions, and bright portions is projected onto the surface of the observation site 2 . No laser light is projected onto the dark portion, and the projected light amount of the laser light onto the dark portion is zero. In addition, in this embodiment, in order to simplify the description, an example of one opening may be described, but the present invention is not limited to this.

Based on such a pixel value Ld based on the pixel signal of the bright area (see FIG. 2A) and the pixel value Lg based on the pixel signal of the dark area (see FIG. 2A), generally the equations (1) and (2) The formula defines D (direct image) and G (global image).

In a comparative example (which will be described later with reference to FIG. 15), dark areas are also irradiated with laser light that is lower in intensity than laser light that is irradiated onto bright areas. Here, b=(brightness of dark area)/(brightness of bright area).

On the other hand, since the light shielding portion 102a according to the present embodiment does not transmit light, the projected light amount in the dark region can always be zero. Therefore, when the diaphragm 102 according to the present embodiment is used, b is always 0 even if the alignment of the irradiation optical system of the laser irradiation unit 10 is changed, and the D (direct image) image and the G (global image) ) the dependence of the parameter b in generating the image can be removed. As described above, since the light shielding portion 102 a does not transmit light, it is possible to generate a dark region on the surface of the observed portion 2 where no light is projected regardless of the distance to the surface of the observed portion 2 . As a result, in equations (1) and (2), it becomes possible to calculate D=Ld and G=Lg.

The camera 20 has a lens section 21 and an imaging section 22 connected to the lens section 21 . The camera 20 is arranged so that the lens portion 21 faces the observed region 2 of the patient 1 and images the observed region 2 irradiated with the laser beam 11 .

The camera 20 captures striped images of bright areas, dark areas, and bright areas on the surface of the observation site 2 . The camera 20 is configured as, for example, a CHU (Camera Head Unit), and is connected to the controller 30 via a predetermined interface or the like. In this embodiment, the camera 20 corresponds to an imaging system.

The lens unit 21 has an optical zoom function. The lens unit 21 generates an optical image of the observed region 2 that is optically enlarged or reduced by controlling imaging parameters such as an F number (aperture value) and optical magnification. A specific configuration for realizing the optical zoom function is not limited, and for example, automatic zooming by electronic control, manual zooming, or the like may be performed as appropriate.

The imaging unit 22 captures an optical image generated by the lens unit 21 and generates pixel signals of the observed region 2 . Here, the pixel signal is a signal capable of forming an image. The pixel signal includes, for example, information such as the luminance value of each pixel. That is, the imaging device of the imaging unit 22 detects light from each point of the observed region 2 (subject) within the imaging range of the imaging unit 22 and converts it into a pixel signal. The pixel signal is divided into a Direct component and a Global component.

When focusing on the position of the subject within the imaging range, the pixel signal detected by direct illumination of the point of interest is defined as the Direct component. A pixel signal detected by illuminating the point of interest via another point is defined as a global component.

Also, the type, format, etc. of the pixel signal are not limited, and any format capable of forming a moving image or a still image, for example, may be used. As the imaging unit 22, for example, an image sensor such as a CMOS (Complementary Metal-Oxide Semiconductor) sensor or a CCD (Charge Coupled Device) sensor is used.

The controller 30 has hardware necessary for configuring a computer, such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and HDD (Hard Disk Drive). In this embodiment, the controller 30 corresponds to a control device.

Each functional block shown in FIG. 1 is realized by the CPU loading the program according to the present technology stored in the ROM or HDD into the RAM and executing it. These functional blocks execute the control method according to the present technology.

The program is installed in the controller 30 via various recording media, for example. Alternatively, program installation may be executed via the Internet or the like.

The specific configuration of the controller 30 is not limited, and devices such as FPGA (Field Programmable Gate Array), image processing IC (Integrated Circuit), and other ASIC (Application Specific Integrated Circuit) may be used.

As shown in FIG. 1, the controller 30 has an irradiation control unit 31, an image acquisition unit 32, a camera control unit 33, a UI acquisition unit 34, a block control unit 35, and an arithmetic processing unit 36 as functional blocks. A processing size table 38 is stored in a storage unit 37 constituted by a ROM of the controller 30 or the like. Dedicated hardware may be appropriately used to implement each functional block.

4A is a block diagram showing the configuration of the irradiation control unit 31. FIG. As shown in FIG. 4A , the irradiation control section 31 has a light source control section 310 and a position control section 312 . The light source control unit 310 controls the irradiation intensity of the laser light 11 emitted from the laser irradiation unit 10 and the like. For example, when observing a D (direct image) image, the light source control unit 310 controls the light intensity of the laser 90 so that the pixel value of the bright area (see FIG. 2A) of the pixel signal generated by the camera 20 becomes a predetermined value. Control.

On the other hand, when observing a G (global) image, the light amount of the laser 90 is controlled so that the pixel value of the dark region (see FIG. 2A) of the pixel signal generated by the camera 20 becomes a predetermined value. Thus, the light source control unit 310 can control the laser 90 to decrease the light intensity of the light source when the predetermined area determined for observation purposes is too bright, and to increase the light intensity of the light source when it is too dark.

FIG. 4B is a diagram showing the relationship between the speckle contrast L40 and the average luminance value of pixel signals generated by the camera 20. FIG. The vertical axis indicates the speckle contrast, and the horizontal axis indicates the average luminance value. The speckle contrast L40 is calculated by the spec calculator 370, which will be described later. As shown in FIG. 4B, the speckle contrast L40 varies in value depending on the average luminance value of the pixel signal. Therefore, the light source control section 310 may control the irradiation intensity of the laser light 11 so that the average luminance value of the pixel signal falls within a predetermined range.

Also, the light source control unit 310 may acquire information on the irradiation intensity of the laser light 11 specified by an operator who operates the biological observation system 100, for example. The light source control unit 310 outputs an instruction to the laser irradiation unit 10 to output the laser light 11 with the designated irradiation intensity. This makes it possible to irradiate the laser beam 11 with the irradiation intensity desired by the operator.

The method for controlling the irradiation intensity of the laser light 11 is not limited. For example, the irradiation intensity of the laser light 11 may be appropriately controlled according to the exposure time of the camera 20 or the like. Note that the light source control unit 310 may appropriately control not only the irradiation intensity of the laser light 11 but also arbitrary parameters such as the wavelength of the laser light 11 and the irradiation area.

The position control unit 312 can control a driving unit (not shown) to move the laser irradiation unit 10 by a predetermined distance at predetermined time intervals.
The image acquisition unit 32 acquires pixel signals generated by the camera 20 . That is, the image acquisition unit 32 acquires pixel signals of the observed region 2 captured by irradiation with the laser light 11 . The pixel signals acquired by the image acquisition section 32 are supplied to the arithmetic processing section 36 . In this embodiment, the image acquisition section 32 corresponds to a pixel signal acquisition section.

The camera control unit 33 is connected to the camera 20 via an interface or the like, and controls the operation of the camera 20. The camera control unit 33 outputs to the camera 20 a signal designating, for example, the zoom amount (optical magnification), aperture, or exposure time of the camera 20 . The camera 20 images the observed region 2 based on the signal output from the camera control section 33 . This allows the operation of camera 20 to be electronically controlled.

In addition, the camera control unit 33 acquires imaging parameters for imaging the observed region 2 . The imaging parameters include the F-number (aperture value) and optical magnification of the lens unit 21 (camera 20). The imaging parameters acquired by the camera control section 33 are output to the block control section 35 . In this embodiment, the imaging parameters correspond to imaging conditions. When the position control unit 312 changes the position of the laser irradiation unit 10 , the camera control unit 33 captures a plurality of images of the observed region 2 in synchronization with the synchronization signal of the position control unit 312 .

The UI acquisition unit 34 acquires instructions and the like input by the operator via a user interface (UI: User Interface) (not shown). As the user interface, for example, a display device such as a display and an input device such as a mouse and a keyboard are appropriately used. The operator inputs instructions using the input device while looking at the operation screen displayed on the display device, for example. The type of user interface is not limited, and for example, a display provided with a touch sensor, a foot switch, a control switch at hand, or the like may be used.

The block control unit 35 has a predicted speckle size calculation unit 40 and a processing size control unit 41 . The predicted speckle size calculator 40 calculates the speckle size based on the imaging parameters input from the camera controller 33 .

The speckle size is the size of individual spots forming speckles. Generally, the speckle size changes according to the imaging system that images the speckle pattern. For example, the speckle size d is given by the following formula.
d=F#×(1+M)×λ×1.22 (3) where F# is the F value of the lens unit 21 and M is the optical magnification M of the lens unit 21 . λ is the wavelength of the irradiated laser light 11 . Below, this formula may be described as a speckle size calculation formula.

In the present embodiment, the predicted speckle size calculation unit 40 calculates the speckle size d using the speckle size calculation formula based on the F number F# and the optical magnification M included in the imaging parameters. Therefore, the predicted speckle size calculator 40 can calculate the speckle size d in the captured speckle pattern. The calculated speckle size d is output to the processing size control section 41 .

The processing size control unit 41 controls the cell size (cell size) that is a pixel block. A cell is, for example, a rectangular block composed of m×n pixels, and is used when calculating the speckle contrast from the pixel signal. The number of pixels (horizontal×vertical) (m×n) corresponds to the cell size. The shape and the like of the cells are not limited, and cells of any shape may be used, for example. Cell and speckle contrast will be described later.

The processing size control unit 41 controls the cell size based on the predicted speckle size d calculated by the speckle size calculation unit 40 . The processing size control unit 41 also controls the cell size according to the image quality mode acquired by the UI acquisition unit 34 . Therefore, the cell size controlled by the processing size control unit 41 is a size corresponding to the speckle size d and the image quality mode.

In this embodiment, the processing size table 38 stored in the storage unit 37 is used when controlling the cell size. The processing size table 38 records the correspondence between the speckle size d, the image quality mode, and the cell size. For example, the processing size control unit 41 acquires the cell size value corresponding to the calculated speckle size d and the specified image quality mode from the processing size table 38 . This makes it possible to easily control the cell size. In this embodiment, the processing size table 38 corresponds to a control table.

Thus, the block control unit 35 calculates the speckle size based on the imaging parameters, and controls the cell size based on the calculated speckle size. That is, the block control unit 35 controls the cell size based on imaging parameters for imaging the observed region 2 .

FIG. 5 is a block diagram showing the configuration of the arithmetic processing unit 36. As shown in FIG. As shown in FIG. 5, the arithmetic processing unit 36 uses cells whose size is controlled by the processing size control unit 41 (block control unit 35) to perform speckle processing based on the pixel signals acquired by the image acquisition unit 32. Calculate the data. That is, the calculation processing unit 36 includes a storage unit 360, a profile generation unit 362, a pixel value range generation unit 364, a first image generation unit 366, a second image generation unit 368, and a speckle calculation unit 370. have Note that the first image generation unit 366 and the second image generation unit 368 according to this embodiment correspond to the image generation unit.

The storage unit 360 stores the pixel signals acquired by the image acquiring unit 32 as a two-dimensional image. Note that the storage unit 360 may be configured within the storage unit 37 .

FIG. 6 is a diagram showing an example of a pixel value profile generated by the profile generator 362. FIG. The above figure is an example of a pixel value profile. The vertical axis indicates pixel values, and the horizontal axis indicates positions on the image. The lower diagram shows a two-dimensional image including bright portions and dark portions generated based on the pixel signals acquired by the image acquisition section 32 . As shown in the lower diagram of FIG. 6, the image of the dark portion corresponding to the light shielding portion 102b also has pixel values. This is caused by the fact that the laser light that is directly applied to the bright area is reflected, scattered, emitted from the dark area, and captured. An image region corresponding to a bright portion (opening portion) directly irradiated with the laser beam 11 is referred to as a D region (direct region). On the other hand, an image area having a predetermined pixel value within a range corresponding to the light shielding portion is called a G area (global area). That is, the G area (global area) is an area where the laser light that entered from the D area (direct area) is reflected and scattered and emitted.

7A and B are schematic diagrams showing cross sections of skin tissue. For example, layer A is the stratum corneum and epidermis, and layer B is the upper layer of the dermis, for example. Capillaries are present in the upper layers of the dermis. FIG. 7A is a diagram schematically showing the laser light 11 in the direct area and the reflected and scattered light EA. FIG. 7B is a diagram schematically showing the laser light 11 in the global area and the reflected and scattered light EB.

As shown in FIG. 7A, in the direct region, the laser beam 11 is also reflected from the A layer, so the weak light reflected and scattered from the B layer is buried in the light reflected and scattered from the A layer. Therefore, in the direct area, the image is captured as the main components of reflected and scattered light EA from the A layer. The reflected/scattered light EA corresponds to, for example, light that is part of the coherent light that is directly applied to the observation site 2 , which is a living body, and is scattered by the blood flow under the tissue of the observation site 2 .

As shown in FIG. 7B, the global area is an area that is not directly irradiated with the laser light 11, and is an area where the light incident from the direct area is reflected and scattered. Therefore, in the global region, the light reflected and scattered from the A layer is reduced, and the reflected and scattered light EB reflected and scattered from the B layer is imaged as the main component.

FIG. 8 is a diagram schematically showing a processing example of the pixel value range generation unit 364. FIG. The upper diagram is a schematic diagram showing the distribution of the laser light 11 on the output side surface of the diaphragm 102 . The vertical axis indicates brightness, and the horizontal axis corresponds to the position of a line that crosses the diaphragm 102. FIG. The lower diagram shows a partial area of the pixel value profile generated by the profile generator 362. FIG.

The pixel value range generation unit 364 generates a representative value of pixel values in the opening region. For example, it is the maximum value, the average value, or the like of the pixel values in the opening region. Subsequently, the pixel value range generation unit 364 generates a pixel value range of the pixel value Lg based on the representative value. For example, a range of 50% to 1/e ² =13.5% of the representative value is generated as the extraction pixel value range of the pixel value Lg in the global area.

FIG. 9 is a diagram showing the correspondence relationship between the extracted pixel value range G9 set by the pixel value range generation unit 364 and the two-dimensional image acquired by the image acquisition unit 32. FIG. The upper diagram shows the pixel value profile generated by the pixel value range generation unit 364 and the extracted pixel value range G9 set by the pixel value range generation unit 364. FIG. The lower diagram shows the two-dimensional image acquired by the image acquisition unit 32, and line L9 indicates the position where the pixel value profile is generated.

FIG. 10 is a diagram showing an example of an image generated by the first image generator 366 based on the extracted pixel value range G9 (FIG. 9). FIG. 10(a) shows an example of an image cut out based on the extracted pixel value range G9 (FIG. 9).

As shown in FIGS. 9 and 10(a), the first image generation unit 366 causes the image acquisition unit 32 to generate an element image in the pixel value range of the pixel value Lg corresponding to the extracted pixel value range G9 (FIG. 9). Cut out from the obtained two-dimensional image. Although the image area on the right side of the direct area is extracted in FIG. 10A, the image area on the left side of the direct area may also be extracted. The first image generation section stores the generated elemental images in the storage section 360 .

FIG. 10(b) is a diagram showing an example of a G (global image) image synthesized by the first image generation unit 366. FIG. As shown in FIG. 10B, the first image generator acquires the generated elemental images from the storage unit 360 and synthesizes the entire image as a G (global image) image.

FIG. 11 is a diagram showing an example of a D (direct image) image generated by the second image generating section 368. FIG. As shown in FIG. 11, the second image generator 368 synthesizes the two-dimensional image acquired by the image acquirer 32, excluding the image below the extraction pixel value range G9 set by the pixel value range generator 364. FIG.

Here, the speckle data is data related to the speckle pattern of the observation site 2. The speckle data is calculated by appropriately processing information such as the luminance value of each pixel included in the pixel signal, for example.

In the present embodiment, the speckle calculator 370 calculates the speckle contrast as the speckle data. In addition to the speckle contrast, for example, the average, variance, standard deviation, etc. of luminance values in the speckle pattern may be calculated as the speckle data. The calculated speckle data can be output to the processing size control unit 41 and the processing size table 38, and used for calibration of the processing size table 38 and the like.

The speckle calculator 370 also generates an observation image of the observed region 2 based on the calculated speckle contrast. The generated observation image is output to a display device such as a display (not shown). In this embodiment, the speckle calculator 370 functions as a calculator and a generator.

12 and 13 are schematic diagrams for explaining an example of speckle contrast calculation. In FIG. 12, luminance values of pixels 43 included in a 3×3 cell 42 are schematically illustrated by contrast.

As shown in FIG. 13, the speckle contrast Cs is given by the following formula using the standard deviation .sigma.
Cs=σ/A (4)

Also, the standard deviation σ and the average value A of the luminance value I(m, n) are given by the following equations.
A=Ave(I(m,n))=Σ[I(m,n)]/N (5) σ=Stdev(I(m,n))=Sqrt((Σ[I(m,n)− Ave]̂2)/N) (6) where the summation symbol Σ represents the sum of the luminance values of all the pixels 43 in the cell 42 . Also, N is the total number of pixels 43 included in the cell 42, and N=3×3=9 in FIG. Note that the method for calculating the speckle contrast Cs is not limited, and for example, instead of the standard deviation σ, the variance σ̂2 of the brightness values I(m, n) may be used. Alternatively, the difference (Imax(m,n)-Imin(m,n)) between the maximum and minimum luminance values I(m,n) in the cell 42 may be used as the speckle contrast Cs.

FIG. 13A shows an example of processing for calculating the speckle contrast Cs using 3×3 cells 42 . For example, as shown in FIG. 13, the position of the upper left pixel 43 of the image 44 is assumed to be coordinates (0, 0). The speckle calculator 370 first sets the cell 42a including the upper left pixel 43. As shown in FIG. In this case, a cell 42a centered on the pixel 43 at coordinates (1, 1) is set (step 1A).

The speckle calculator 370 calculates the speckle contrast Cs (1, 1) in the cell 42a centered at the coordinates (1, 1). That is, Cs(1, 1) is calculated from the brightness values of the center pixel 43 and eight pixels 43 around it. The calculated speckle contrast Cs(1,1) is recorded as the speckle contrast Cs corresponding to the pixel 43 at coordinates (1,1) (step 1B).

Next, the speckle calculation unit 370 sets a cell 42b centered at the coordinates (2, 1), which is shifted one pixel to the right from the coordinates (1, 1) (step 2A). The speckle calculator 370 calculates the speckle contrast Cs (2, 1) in the cell 42b and records it as the speckle contrast Cs of the pixel 43 at the coordinates (2, 1) (step 2B).

In this way, the center of the cell 42 is moved pixel by pixel, and the process of calculating the speckle contrast Cs of the pixel 43 at the center of the cell 42 is executed. Thereby, the speckle contrast Cs corresponding to each pixel 43 included in the pixel signal is sequentially calculated.

The method of calculating the speckle contrast Cs using the cell 42 is not limited. For example, the calculated speckle contrast Cs may be assigned to other pixels 43 within the cell 42 that are different from the central pixel 43 . Further, the amount, direction, order, and the like of moving the cells 42 are not limited, and may be changed as appropriate according to, for example, the processing time required for image processing.

FIG. 13A schematically shows the overall image of the process of calculating the speckle contrast Cs. The diagram on the left side of FIG. 13A is a schematic diagram of the global image generated by the second image generator. The speckle calculator 370 starts the process of calculating the speckle contrast Cs from the upper left of the global image 50 . The original image for calculating the speckle contrast Cs, that is, the global image 50 is hereinafter referred to as the speckle image 50 .

The speckle calculator 370 generates a speckle contrast image 60 as an observation image based on the calculated speckle contrast Cs. The diagram on the right side of FIG. 13B is a schematic diagram of the speckle contrast image 60 .

The speckle contrast image 60 is generated by converting the value of the speckle contrast Cs into a luminance value. For example, a pixel with a high speckle contrast Cs value is set to a bright luminance value, and a pixel with a low Cs value is set to a dark luminance value. A method or the like for converting the speckle contrast Cs into a luminance value is not limited, and any method may be used. For example, a brightness value may be set in which the brightness is inverted with respect to the level of the speckle contrast Cs.

FIG. 14 is a diagram for explaining the characteristics of speckle patterns. The image shown in the upper right of FIG. 14 is an image (speckle image 50a) captured by irradiating the observation target in a stationary state with the laser beam 11. As shown in FIG. The image shown in the upper left is an image (speckle image 50b) captured by irradiating the observation target in a moving state with the laser beam 11. FIG.

In general, when a highly coherent light such as laser light 11 is irradiated onto an observation target, the phase of laser light 11 (reflected light) reflected by the observation target changes randomly. The laser beams 11 with random phases interfere with each other to form a bright and dark speckle pattern. For example, when the observation target is in a stationary state, the positions where interference occurs are stable, so a clear speckle pattern is formed as shown in the speckle image 50a on the right side.

On the other hand, when the laser beam 11 irradiates a moving object, for example, blood flow, the position where interference occurs changes, and the light and dark pattern of the speckle pattern changes. is reduced (left speckle image 50b). The degree to which the contrast between light and dark decreases is, for example, a value corresponding to the amount of movement of the camera 20 within the exposure time. In other words, the decrease in contrast between light and dark is an index reflecting speed.

A graph showing the luminance distribution of the speckle images 50a and 50b in the stationary state and the moving state is shown in the lower part of FIG. The horizontal axis of the graph is the luminance value, and the vertical axis is the number of pixels (distribution) of each luminance value. The luminance distributions in the speckle images 50a and 50b in the static and moving states are illustrated by dotted and solid lines, respectively.

As shown in the graph, when the observation target is stationary, the brightness distribution is wider than when it is moving. That is, the speckle image 50a in the stationary state is an image having a wide brightness difference between bright pixels and dark pixels and a large light-dark contrast. On the other hand, the speckle image 50b in the moving state has a narrow luminance difference between bright pixels and dark pixels and a small light-dark contrast.

FIG. 15 is a diagram showing a configuration example of a laser irradiation unit 10a of a comparative example. As shown in FIG. 15, in the laser irradiation unit 10a of the comparative example, instead of the diaphragm 102, for example, a diffusion medium 102a having different light transmittances in stripes is configured. Since the transmittance of the laser light is varied by the diffusing medium 102a, the dark part of the surface of the subject 2 is also irradiated with the laser light. As a result, the aforementioned b value becomes dependent on the distance of the object plane. Therefore, it is necessary to derive the b-value each time the alignment of the optical system changes.

FIG. 16 is a diagram showing a G (global) image of a comparative example captured by the imaging system of FIG. 15 and a G (global) image according to the present disclosure. The average finger speckle contrast Cs of the comparative G (global) image is 14, and the average finger speckle contrast Cs of the G (global) image according to the present disclosure is 10. As described above, the lower the value of the speckle contrast Cs, the more motion state images are present in the G (global) image. As can be seen from this, using the diaphragm 102 of the present disclosure indicates that more information on the blood flow component can be obtained than when using the diffusion medium 102a of the comparative example.

FIG. 17 is a flowchart showing a processing example of the biological observation system 100. FIG. As shown in FIG. 17, first, under the control of the irradiation control unit 31 and the camera control unit 33, irradiation by the laser irradiation unit 10 and imaging by the camera 20 are started, and the image acquisition unit 32 acquires image data (step S100).

Next, the profile generator 362 generates a profile that traverses the bright area, and the pixel range generator 364 generates the pixel value range of the G area (step S102). Note that the generation of the pixel value range may be performed once at the beginning and omitted in the next loop.

Next, the first image generation unit 366 generates an elemental image of the G area based on the pixel value range from the image data, and stores it in the storage unit 360. Further, the first image generation unit 366 generates an element image of the D region by excluding the pixel range below the pixel value range from the image data, and stores it in the storage unit 360 (step S104).

Next, the irradiation control unit 31 determines whether or not the irradiation of the laser irradiation unit 10 has been completed up to a predetermined range (step S106). If it is determined that the predetermined range has not been completed (NO in step S106), the irradiation position is changed, and the processing from step S100 is repeated.

On the other hand, when the irradiation control unit 31 determines that the irradiation has finished up to the predetermined range (YES in step S106), it stops laser irradiation. Subsequently, the first image generation unit 366 generates a G image using the element images of the G area stored in the storage unit 360, and the second image generation unit 368 generates an image of the D area stored in the storage unit 360. A D image is generated using the element image (step S108).

Next, the speckle calculator 370 generates a speckle contrast image as an observation image based on the speckle contrast Cs of the generated G image and D image as an operator, and outputs the speckle contrast image to the display. (step S110). Then, the display displays the speckle contrast images of the G image and the D image (step S112), and the process ends.

As described above, according to the present embodiment, the laser irradiation unit 10 emits coherent light to the observation site 2 of the living body through the diaphragm 102 having the light shielding unit 02b for shielding light and the aperture 102a for transmitting light. and the first image generation unit 366 generates a first image based on the pixel signals of the dark region not irradiated with the coherent light in the pixel signals including the region of the observation site 2 irradiated with the coherent light. I decided to Thereby, the pixel signals based on the light scattered by the layer B, which is the lower layer of the tissue of the observation site 2, can be obtained while the reflected light from the layer A, which is the surface layer of the observation site 2, is suppressed. Therefore, an observation image of the underlying layer of the tissue of the observation site 2 can be generated with lower noise.

(Second embodiment)
The living body observation system 100 according to the first embodiment has a fixed diaphragm 102, whereas the living body observation system 100 according to the second embodiment has a variable diaphragm 1020. FIG. Differences from the biological observation system 100 according to the first embodiment will be described below.

FIG. 18 is a side sectional view of the diaphragm 1020 according to the second embodiment. As shown in FIG. 18, the diaphragm 1020 has a plurality of movable diaphragms 1020a and 1020b. The positions of the plurality of movable diaphragms 1020a and 1020b are configured to be changeable, and the interval D1020 between the apertures and the width D1040 of the diaphragm can be changed.

FIG. 19 is a diagram showing a block diagram of the irradiation control unit 31 according to the second embodiment. As shown in FIG. 19, it differs from the irradiation control section 31 according to the first embodiment in that it further includes an aperture control section 314 .

The aperture control unit 314 performs position control of the plurality of movable apertures 1020 a and 1020 b of the aperture 1020 based on the pixel value profile generated by the profile generation unit 362 . In addition, the aperture control unit 314 can also perform control for parallel movement of the movable apertures 1020a and 1020b.

FIG. 20 is a diagram for explaining a control example of the aperture control unit 314. FIG. The left diagram is a schematic diagram showing the distribution of the laser light 11 on the exit side surface of the diaphragm 1020 . The vertical axis indicates brightness, and the horizontal axis corresponds to the position of a line that crosses aperture 1020 . The right figure is a profile on the observation site 2 corresponding to the opening and the light shielding part in the left figure. The vertical axis indicates pixel values, and the horizontal axis indicates positions. The diaphragm control unit 314 controls the aperture interval D1020 and the diaphragm width D1040 based on the maximum pixel value L2 of the bright portion and the minimum pixel value L1 of the dark portion of the profile.

FIG. 21 is another diagram illustrating a control example of the aperture control unit 314. FIG. The left diagram is a schematic diagram showing the distribution of the laser light 11 on the surface of the exit side of the diaphragm 1020, centering on the aperture. The vertical axis indicates brightness, and the horizontal axis corresponds to the position of a line that crosses aperture 1020 . The right figure is a profile on the observation site 2 corresponding to the opening and the light shielding part in the left figure. The vertical axis indicates pixel values, and the horizontal axis indicates positions. The diaphragm control unit 314 controls the aperture interval D1020 and the diaphragm width D1040 based on the maximum pixel value L2 of the bright portion and the minimum pixel value L1 of the dark portion of the profile.

FIG. 22 is a diagram explaining still another control example of the aperture control unit 314. In FIG. (a) is a diagram showing a profile on the observed region 2 before control. (b) is a diagram showing a profile on the observation site 2 after control. (c) shows the phase pitch of the diaphragm 1020; FIG. 4 is a diagram showing a profile on an observation site 2; The vertical axis indicates pixel values, and the horizontal axis indicates positions. The vertical axis indicates the pixel value, and the horizontal axis indicates the position.

FIG. 23 is a flowchart showing a processing example of the aperture control unit 314. FIG. A processing example will be described with reference to FIG.

First, according to the control of the irradiation control unit 31 and the camera control unit 33, the laser irradiation unit 10 irradiates the laser through the diaphragm 1020, and the image acquisition unit 32 acquires the image data captured by the camera 20 (step S200). .

Next, as shown in (a) of FIG. 22, the profile generator 362 generates a profile that crosses the bright area and the bright area (step S202). Subsequently, the aperture control unit 314 calculates the geometrical magnification between the laser irradiation unit 10 and the observed region 2 from the relationship between the intervals D1020 and D1040 and the intervals between the bright and dark portions on the profile (step S204).

Next, as shown in (a) of FIG. 22, the aperture control unit 314 extracts a range L_diff based on a value of 1/e ² =13.5% of the maximum value L2 of the profile. More specifically, the aperture control unit 314 extracts the range from the boundary point between the bright part and the dark part to the value of 1/e ² =13.5% of the maximum value L2 of the profile as the range L_diff (step S204). .

Next, as shown in (b) of FIG. 22, the aperture control unit 314 sets the width L_dark of the dark portion to a range equal to or less than twice the range L_dif, and determines the width of the light shielding portion based on the magnification calculated in step S204. D1040 is adjusted (step S206). Subsequently, the aperture control unit 314 calculates the width L_ill of the bright portion to be the same value as the width L_dark, and adjusts the width D1020 of the aperture based on the magnification calculated in step S204 (step S206).

Next, the diaphragm control unit 314 sets the movement step width L_ill_step of the diaphragm 1020 to be less than the range L_diff, sets the movement step width of the diaphragm 1020 based on the magnification, and ends the setting process.

As described above, according to the present embodiment, the diaphragm 1020 is composed of a plurality of movable diaphragms 1020a and 1020b, and the diaphragm controller 314 controls the movable diaphragms 1020a and 1020b based on the profile crossing the bright area and the and This makes it possible to set the pixel values and the ratio of the bright and dark portions in the image data captured by the camera 20 to predetermined values.

This technology can be configured as follows.

(1) an irradiation unit that irradiates coherent light onto an observation site of a living body through a diaphragm having a light shielding portion that blocks light and an opening that transmits light;
an image acquisition unit that acquires pixel signals including a region of the observation site irradiated with the coherent light;
an image generating unit that generates a first image based on pixel signals in a dark area not irradiated with the coherent light in the pixel signals;
A living body observation system.

(2) The biological observation system according to (1), wherein the light shielding section is made of metal that does not transmit light.

(3) the pixel signals in the dark region are based on light that is part of the coherent light that is directly applied to the living body and is scattered by blood flow under the tissue of the observation site; The in vivo observation system described.

(4) further comprising a pixel range setting unit for setting a predetermined pixel value range based on a profile, which is a pixel row with respect to a positional change on the image based on the pixel signal;
The biological observation system according to (2), wherein the image generator generates the first image based on the predetermined pixel value range.

(5) The living body according to (4), further comprising: a second image generation unit that generates a second image based on pixel signals of a bright region in the image directly irradiated with the coherent light. observation system.

(6) The biological observation system according to (5), further comprising a speckle calculation unit that calculates speckle data based on at least one of the first image and the second image.

(7) the speckle data includes speckle contrast;
The biological observation system according to (6), wherein the speckle calculator generates an observation image based on the speckle contrast.

(8) the pixel signal acquisition unit acquires a plurality of images in which the region of the observation site irradiated with the coherent light is changed, respectively;
The biological observation system according to (7), wherein the image generator generates the first image based on the plurality of images.

(9) The biological observation system according to (8), further comprising an irradiation control unit that controls the irradiation intensity of the coherent light based on the speckle contrast value in the observation image.

(10) The biological observation system according to (9), wherein the irradiation control unit controls the irradiation intensity of the coherent light based on pixel values of at least one of the dark region and the bright region in the image. .

(11) The aperture is a variable aperture, and an aperture control unit that sets a width of an aperture and a width between apertures based on pixel values in the dark region and the bright region in the image. The biological observation system according to (10), further comprising:

(12) According to (11), the aperture control unit sets the width between the openings so that a ratio of predetermined pixel values in the dark area and the bright area is within a predetermined range. in vivo observation system.

(13) A blood flow meter device using the biological observation system according to any one of (1) to (12).

(14) A microscope apparatus using the biological observation system according to any one of (1) to (12).

(15) An endoscope apparatus using the biological observation system according to any one of (1) to (12).

(16) an irradiation step of irradiating an observation site of a living body with coherent light through a diaphragm having a light shielding portion for shielding light and an opening for transmitting light;
a pixel signal acquiring step of acquiring a pixel signal including a region of the observation site irradiated with the coherent light;
an image generating step of generating a first image based on the pixel signals in the dark area not irradiated with the coherent light in the pixel signals;
A living body observation method.

(17) a light source that produces coherent light;
A movable diaphragm having a light shielding portion that shields the coherent light and an opening that transmits the light,
At least one of the width of the light shielding portion and the width of the opening is controlled based on pixel signals of a dark region of an observation site not irradiated with the coherent light in a living body irradiated with the coherent light.

Aspects of the present disclosure are not limited to the individual embodiments described above, but include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-described contents. That is, various additions, changes, and partial deletions are possible without departing from the conceptual idea and spirit of the present disclosure derived from the content defined in the claims and equivalents thereof.

10: laser irradiation unit, 32: image acquisition unit, 100: biological observation system, 102: diaphragm, 102a: opening, 102b: light shielding unit, 366: first image generation unit, 368: second image generation unit, 370: Speckle calculator 1020: Aperture.

Claims (17)

1. an irradiation unit that irradiates coherent light onto an observation site of a living body through a diaphragm having a light shielding portion that shields light and an opening that transmits light;
   a pixel signal acquisition unit that acquires pixel signals including a region of the observation site irradiated with the coherent light;
   an image generating unit that generates a first image based on pixel signals in a dark area not irradiated with the coherent light in the pixel signals;
   A living body observation system.
2. The living body observation system according to claim 1, wherein the light shielding part is made of a metal that does not transmit light.
3. 3. The living body according to claim 2, wherein the pixel signals of said dark region are based on light in which part of said coherent light directly irradiated to said living body is scattered by blood flow under tissue of said observation site. observation system.
4. Further comprising a pixel range setting unit for setting a predetermined pixel value range based on a profile, which is a pixel row with respect to a positional change on the image based on the pixel signal,
   3. The biological observation system according to claim 2, wherein said image generator generates said first image based on said predetermined pixel value range.
5. The living body observation system according to claim 4, further comprising an image generation unit that generates a second image based on pixel signals in the bright region irradiated with the coherent light.
6. The biological observation system according to claim 5, further comprising a speckle calculation unit that calculates speckle data based on at least one of the first image and the second image.
7. The speckle data includes speckle contrast,
   7. The living body observation system according to claim 6, wherein said speckle calculator generates an observation image based on said speckle contrast.
8. The pixel signal acquisition unit acquires a plurality of pixel signals obtained by changing the region of the observation site irradiated with the coherent light,
   The biological observation system according to claim 7, wherein the image generator generates the first image based on the plurality of pixel signals.
9. The living body observation system according to claim 8, further comprising an irradiation control unit that controls the irradiation intensity of the coherent light based on the speckle contrast value in the observation image.
10. The biological observation system according to claim 9, wherein the irradiation control unit controls the irradiation intensity of the coherent light based on pixel signals of at least one of the dark region and the bright region in the pixel signals.
11. The aperture is a variable aperture, and further includes an aperture controller that sets a width of an aperture and a width between apertures based on pixel values in the dark region and the bright region in the pixel signal. 11. The biological observation system according to claim 10.
12. 12. The living body observation according to claim 11, wherein said aperture control unit sets the width between said openings so that a ratio of predetermined pixel values in said dark area and said bright area is within a predetermined range. system.
13. A blood flow meter device using the biological observation system according to claim 1.
14. A microscope device using the biological observation system according to claim 1.
15. An endoscope device using the living body observation system according to claim 1.
16. an irradiation step of irradiating coherent light onto an observation site of a living body through an aperture having a light shielding portion for shielding light and an opening for transmitting light;
    a pixel signal acquiring step of acquiring a pixel signal including a region of the observation site irradiated with the coherent light;
    an image generating step of generating a first image based on pixel signals of a dark region in the image not directly irradiated with the coherent light;
    A living body observation method.
17. a light source that produces coherent light;
    A movable diaphragm having a light shielding portion that shields the coherent light and an opening that transmits the light,
    At least one of the width of the light shielding portion and the width of the opening is controlled based on pixel signals of a dark region of an observation site not irradiated with the coherent light in a living body irradiated with the coherent light.

Images