JP4409322B2 - Endoscope and video system - Google Patents

Description

The present invention relates to an endoscope for observing the cells of the expanded video system and in vivo that are suitable for cell observation in vivo.

  Conventional endoscopes have a wide viewing angle of about 90 ° to 140 ° so that a tissue inside a living body can be observed and examined without overlooking the lesion.

  This conventional endoscope obtains a magnified image and a reduced image of the observation object by changing the distance from the subject. For example, a deep depth of field at a fixed focal point can be observed so that a range from 3 mm to 50 mm can be observed without focus adjustment. Have.

The image display magnification of the conventional endoscope is approximately 30 to 50 times on a 14-inch monitor screen and has a magnification sufficient for observing a diseased tissue.
A zoom optical system is used for further enlargement observation with a conventional endoscope. The maximum magnification of the zoom optical system is approximately 70 times on a 14-inch monitor screen. Since the zoom optical system has a built-in zoom lens operating unit, the zoom optical system is limitedly applied due to an increase in the outer diameter of the endoscope tip insertion unit to 10 mm or more and the complexity of operation during endoscope observation.

  Here, with reference to FIG. 1, a description will be given of biological tissues that are conventionally observed with an endoscope and the reason why they can be observed as a subject. Conventional biological tissue to be observed with an endoscope is composed of a substantial tissue in which blood vessels and the like are running and transparent epithelial cells in the upper layer. Illumination light that is obliquely illuminated from above by the endoscope passes through the transparent epithelial cells and reaches the parenchyma, where it is scattered (A1, A2 in the figure) and most of them enter the epithelial cells again. When illumination light passes through epithelial cells, light diffraction (B1 and B2 in the figure) occurs due to cell walls and cell nuclei. However, since the intensity is very small, the intensity of light scattered by the parenchyma is dominant. Become. As a result, only the parenchyma is observed through the objective optical system of the conventional endoscope.

  When it is difficult to determine the presence or absence of an abnormality based on the findings of tissue images, such as very small lesions, suspicious tissue is collected using a treatment tool while observing with an endoscope. The collected tissue is examined at a cell level by a microscope. In contrast to an endoscope, an illumination optical system is placed around the objective optical system for down-tilt illumination, whereas in a microscope, the objective optical system and the illumination optical system are placed facing each other across the specimen, and the specimen is transmitted from the back. Observe by lighting. The specimen is processed in advance to a state suitable for observation. For example, in order to suppress light scattering and facilitate light transmission, treatments such as removing the substantial tissue, slicing thinly, and adding contrast by staining are performed.

  The reason why these specimens can be observed with a microscope will be described with reference to FIG. The prepared specimen is fixed on the cover glass and illuminated from below. The illumination light is diffracted by the cell wall and cell nucleus when passing through the specimen, and the diffracted light interferes with each other and strengthens and weakens the contrast, so the specimen can be observed with the upper objective optical system. become.

  A laser scanning confocal endoscope has been proposed as one that can be inserted into a living body and has a resolution necessary for cell observation. The confocal optical system is configured such that pinholes such as an air disk are arranged at a position conjugate with the image plane, and information about the diffraction limit is acquired for each point from a subject in the field of view. Laser light is scanned on the subject by the light projecting optical system, and information about each point obtained from the reflected light from the subject is combined to construct information about a plane or a solid as an image. It has high resolution not only in the horizontal direction in the plane but also in the depth direction.

  In the conventional method of taking a living tissue out of the body and making a diagnosis, it takes several days to several weeks to determine whether or not the tissue is abnormal. In addition, the cell specimen to be observed is a specimen obtained by separating and fixing a small part of the collected tissue. Therefore, although information as a cell structure can be obtained simply, it is significantly different from the environment in the living body, so that it is not possible to obtain functional information including, for example, the reflux state of the body fluid filling the cells. Therefore, there is a need for a magnifying endoscope that can observe cells inside a living body as they are in real time.

  In order to image diseases inside the living body at the cellular level, a small video module equipped with an objective optical system having high imaging magnification and high resolution comparable to a microscope is required. The objective optical system does not satisfy the above required specifications. In the conventional endoscope, as described with reference to FIG. 1, when illumination light passes through epithelial cells, diffraction of light (B1 and B2 in the figure) occurs due to cell walls and cell nuclei. The intensity of the light (A1, A2 in the figure) scattered by the substantial tissue becomes dominant. As a result, information from the epithelial tissue is buried, and only information from the real tissue is imaged through the objective optical system of the conventional endoscope.

  Moreover, although the objective optical system of the microscope is satisfactory in terms of performance, it is large and cannot be introduced into a living body. Laser scanning confocal endoscopes have a problem in scanning speed, and have not yet achieved real-time observation in vivo.

As described above, a video system that satisfies the specifications necessary for observing living cells has not been realized at present.
An object of the present invention is to solve the problems described above, to provide a video system for realizing a real-time cell observation in vivo, to provide an endoscope for and producing somatic cells observed It is.

In order to solve the above problems, the endoscope of the present invention has the following features.
(1) An endoscope provided with an observation device and an illumination device for observing a living tissue , wherein the observation device includes an objective optical system, and the observation device and the illumination device are focused on the objective optical system. when the position is located on the upper layer tissue of the living body tissue, and the illumination field of the illumination device to be illuminated on the upper layer tissue from the distal end of the endoscope with the objective optical system of the observation field of view are separated, and, as light directed on the upper layer tissue from the light transmittance is lower underlying tissue as compared to the upper layer tissue after passing through the upper layer tissue from the lighting device, it forms illumination field involving observation field of view of the objective optical system The endoscope is characterized in that the endoscope is arranged .

(2) An endoscope for observing living tissue, including a video module having an objective optical system with an imaging magnification greater than 1, wherein the endoscope includes an illuminating device, and the video module and the illuminating device When the focus position of the video module is located in the upper layer tissue of the living tissue, the observation field of the video module and the illumination field of the illuminating device irradiated to the upper layer tissue from the distal end side of the endoscope And the light that is transmitted from the illumination device through the upper layer tissue and has a lower light transmittance than the upper layer tissue toward the upper layer tissue includes the observation field of view of the video module. An endoscope characterized by being arranged so as to form an illumination field.

In order to solve the above problems, the video system of the present invention has the following features.
( 3 ) A video system for observing a living tissue , comprising a video module having an objective optical system and an illumination optical system with an imaging magnification larger than 1, and a light source for supplying illumination light. The illumination device is configured to irradiate the upper layer tissue from the observation field of view of the video module and the distal end side of the endoscope when the in-focus position of the video module is located in the upper layer tissue of the living tissue. Light that passes through the upper layer tissue from the illumination device and has a lower light transmittance than the upper layer tissue and travels from the lower layer tissue toward the upper layer tissue is not observed in the observation field of the video module. so as to form a illumination field comprising, disposed in the light source, a blue wavelength region, green wavelength region among the illumination light in the red wavelength region, two wavelengths illumination light in a blue wavelength region or the red wavelength region Video system characterized in that it is divided into T1, T2, waveband selecting means for blocking the wavelength band T1 near the green wavelength region is provided.

(4) The video system according to the item (3), wherein the wavelength band T1 is 600 nm to 700 nm.

The present invention more expanded video system and an endoscope, it is possible to observe the cells in vivo in real time.

  A case where the enlarged video system of the present invention is applied to an endoscope and a living cell is observed will be described.

  In this case, in order to inspect the diseased tissue in a wide body cavity without being overlooked, it is first observed with a conventional endoscope having a wide field of view. Next, an endoscope to which the magnified video system of the present invention is applied (hereinafter simply referred to as a magnified endoscope) is applied to a region where it is difficult to determine whether or not the tissue is a lesion tissue from a tissue image of a conventional endoscope. ) To observe at the cell level.

  When enlarging and observing cells, a pigment is applied in advance as necessary. When a certain amount of time has elapsed after the pigment is sprayed, the subject can be contrasted using the difference in the time during which the cell nuclei and other parts constituting the cells eject the pigment. After that, while observing with a conventional endoscope, the magnifying endoscope is guided to the site to be observed, and the tip is brought into close contact with the subject and fixed. It is preferable that the tissue image of the conventional endoscope and the cell image of the magnifying endoscope are simultaneously displayed on the TV monitor. Thereby, it is possible to perform an enlarged observation of a cell nucleus or a cell wall by reliably guiding to a minute region of interest in a wide observation field of view.

Before describing the enlarged video system of the present invention in detail, specifications required for a video module used in the enlarged video system will be described.
First, the magnification necessary for visualizing the cell microstructure will be described. The observation magnification βm on the monitor is given by the following equation.

βm = β0 × βd
Here, β0 is the magnification of the objective optical system, and is the magnification at which the subject is imaged on the image sensor. Βd is display magnification is obtained by dividing the monitor display screen size in the imaging screen size of the image sensor.

  The observation magnification on a 14-inch monitor that can be realized with a conventional endoscope is about 30 to 50 times. In a zoom optical system having an enlargement function, the magnification is about 70 times. Cell observation requires an observation magnification of about 200 to 2000 times on a 14-inch monitor. For this purpose, the objective optical system desirably satisfies the following conditions.

1 <| βo | ≦ 10 (1)
Where βo is the magnification of the objective optical system.
0.9 ≦ | coswy '/ coswy | ≦ 1.1 (3)
However, wy ′ represents an angle at which a principal ray corresponding to the maximum viewing angle is incident on the imaging surface, and wy represents a half of the viewing angle. If the lower limit of this conditional expression is not reached, the incident angle to the image sensor increases, and the uniformity of image quality (for example, color reproducibility and brightness) cannot be maintained within the field of view. If the upper limit of this conditional expression is exceeded, the viewing angle becomes large, and the necessary magnification cannot be ensured.

Next, the resolution will be described.
Although the diseased tissue can be identified with a resolution on the order of millimeters or submillimeters, when observing cells, a resolution in units of microns or submicrons is required. In addition, in order to image fine information of a subject that is transparent and has a small difference in refractive index and low contrast, it is necessary to enhance contrast using interference of diffracted light from the subject. For this reason, it is necessary for the objective optical system to increase the object-side numerical aperture NA so that higher-order diffracted light can be taken in, and it is desirable to satisfy the following conditions.

0.1 ≦ NA ≦ 0.8 (4)
In particular, when observing a cell wall, it is desirable to satisfy the following conditions.
0.3 ≦ NA ≦ 0.8 (4 ')
Furthermore, in order to achieve both high contrast and image definition, the resolution of the objective optical system must be set higher than the resolution determined by the pitch of the image sensor and lower than the resolution determined by the diffraction limit, which satisfies the following conditions: It is desirable.

0.1 ≦ | p × (NA) ² /(0.61×λ×βo)|≦0.8 (6)
Here, p is the pixel size of the image sensor, NA is the object-side numerical aperture of the objective optical system, λ is the e-line wavelength 0.546 [μm], and βo is the magnification of the objective optical system. If the lower limit of this conditional expression is not reached, sufficient contrast cannot be obtained. If the upper limit of this conditional expression is exceeded, aberration correction becomes difficult and a fine image cannot be obtained.

Next, downsizing will be described.
For example, in order to guide the magnifying endoscope to the subject through the treatment instrument insertion channel of the conventional endoscope, it is desirable that the outer diameter of the magnifying endoscope is φ4 mm or less. Accordingly, it is desirable to reduce the outer diameter of the objective optical system to about φ2 mm or less.

  A high-magnification magnification and high resolution, and a compact objective optical system that includes a lens group having a positive focal length in order from the object side and an aperture stop, and satisfies the following conditions: Is desirable.

0.2 ≦ φ1 / (φ2 × f1) ≦ 2 (5)
Where φ1 is the aperture diameter of the aperture stop, φ2 is the maximum outer diameter of the objective optical system, and f1 is the focal length of the lens group having a positive focal length.

  This conditional expression is a condition for achieving a reduction in size by avoiding an increase in the aperture of the objective optical system with an increase in NA. If the lower limit of the conditional expression is not reached, the overall length and the outer diameter increase, and the objective optical system becomes larger. It becomes difficult to downsize the system. If the upper limit of the conditional expression is exceeded, aberration correction becomes difficult.

  Further, in order to obtain a field of view without bending to the periphery, it is desirable that the objective optical system is composed of a front group having a positive focal length, an aperture stop, and a rear group having a positive focal length in order from the object side. . At this time, it is desirable to satisfy the following conditions in order to achieve both miniaturization and high magnification.

2 ≦ f2 / f1 ≦ 10 (2)
Here, f1 is the focal length of the front group, and f2 is the focal length of the rear group. If the lower limit of this conditional expression is not reached, the necessary magnification cannot be secured. If the upper limit of the conditional expression is exceeded, the overall length and the outer diameter become large, making it difficult to reduce the size.

Examples of the video module according to the present invention will be described below.
Example 1
FIG. 11 is a lens cross-sectional view of Example 1, and Table 1 shows lens data.

Hereinafter, the configuration of the first embodiment will be described with reference to FIG.
The objective unit incorporates an objective lens group 101 having the same outer diameter in the objective frame 102. The objective lens group 101 includes a first group having a positive focal length in order from the object side, an aperture stop 103, and a second group having a positive focal length. The imaging element 105 is fixed to the imaging frame 106 via the cover glass 104 and constitutes an imaging unit.

  The video module performs focus adjustment by changing the distance 107 between the objective unit and the imaging unit. The insertion portion of the magnifying endoscope includes a distal end hard portion 108 and an outer surface portion 110. The video module is fixed in the insertion portion via the intermediate member 109.

  FIG.11 (b) shows the cross section which looked at Fig.11 (a) from the direction of A arrow. The intermediate member 109 is provided with a notch (shaded portion in the drawing) on the outer periphery, and an illumination fiber 111 is internally fixed to the insertion portion. After the intermediate member 109 and the illumination fiber are fixed to the distal end hard portion 108, the video module is inserted and fixed.

When adjustment of the imaging magnification or the like is necessary, the adjustment can be performed by increasing or decreasing the interval between the interval adjusting units 112 a and 112 b provided before and after the brightness stop 103. For the interval adjustment, an interval adjustment ring made of a very thin plate material is used. For this reason, the spacing adjustment unit is designed on the assumption that a plurality of thin plates are stacked in advance, and the variation in the spacing after assembling the components due to the dimensional tolerance of the components actually used will cause Adjustment is performed by increasing or decreasing the number of sheets.
Table 1
Curvature radius Interval Refractive index Abbe number Lens outer
INF 0.46 1.5183 64.14 1
0.84 0.17 1
INF 0.4 1.7323 54.68 1
-0.817 0.05 1
1.353 0.65 1.7323 54.68 1
-0.703 0.25 1.7044 30.131
-3.804 0.09 1
INF (Aperture) 0.03 1
INF 0.4 1.5156 75.00 1
INF 0.2 1
1.566 0.4 1.67 48.32 1
-1.566 0.2 1
-0.729 0.3 1.5198 52.43 1
INF 0.56 1
INF 0.4 1.5183 64.14
INF 0.01 1.5119 63.00
INF 0.4 1.6138 50.20
INF 0.01 1.5220 63.00
INF 0
Object distance 0 Image height 0.500
(Example 2)
FIG. 12 is a lens cross-sectional view of Example 2, and Table 2 shows lens data.

The structural parts similar to those of the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
Table 2
Radius of curvature Interval Refractive index Abbe number Lens outer diameter
INF 0.88 1.8882 40.76 1.2
-0.703 0.05 1
INF 0.4 1.5183 64.14 1.2
-1.485 0.05 1
2.085 0.76 1.8081 46.57 1.2
-0.703 0.25 1.8126 25.42 1.2
INF 0.05 1
INF (Aperture) 0.03 1
INF 0.4 1.5156 75.00 1.2
INF 0.43 1
1.131 0.5 1.8395 42.72 1.2
-3.127 0.2 1
-1.061 0.3 1.8126 25.42 1.2
INF 0.2 1
-0.592 0.3 1.8081 46.57 1.2
2.132 0.77 1.8126 25.42 1.2
-1.262 0.77 1
INF 0.4 1.5183 64.14
INF 0.01 1.5119 63.00
INF 0.4 1.6138 50.20
INF 0.01 1.5220 63.00
INF 0 1
Object distance 0 Image height 0.500
Table 3 shows the specifications of the examples, and Table 4 shows the values of the conditional expressions.

Table 3
Item Symbol Unit Example 1 Example 2
Objective magnification βo -2.678847 -6.63
Front group focal length f1 [mm] 0.765 0.591
Rear group focal length f2 [mm] 3.476 4.557
Focal length f [mm] 0.657 0.797
Half of viewing angle wy [deg] 6.141 3.95
Chief ray emission angle wy '[deg] 13.965 6.02
Object side numerical aperture NA 0.2184 0.55
Diaphragm diameter φ1 [mm] 0.36 0.66
Maximum lens diameter φ2 [m] 1 1.2
Pitch P [μ] 4 4
Reference wavelength λ [μ] 0.546 0.546

Table 4
No. Conditional expression Example 1 Example 2
1 1 <| βo | <10 2.680 6.630
2 2 ≦ f2 / f1 ≦ 10 4.544 7.711
3 0.9 ≦ | coswy '/ coswy | ≦ 1.1 0.976 0.997
4 0.1 ≦ NA ≦ 0.8 0.220 0.550
5 0.2 ≦ φ1 / (φ2 × f1) ≦ 2 0.471 0.931
6 0.1 ≦ | p × (NA) ² /(0.61×λ×βo)|≦0.8 0.215 0.544

Next, a video system suitable for cell observation in a living body will be described.

  As described above, the living tissue is composed of a substantial tissue in which blood vessels and the like are running and a transparent epithelial cell in the upper layer. In order to contrast only the cell nucleus and other parts constituting this transparent epithelial cell, and observe only the epithelial cell located in the desired observation range without being affected by the underlying tissue located below, Ingenuity is necessary.

  For example, when contrast is given by staining cells in blue, the optimum video system for clearly observing only the cell layer of interest has the following configuration.

FIG. 3 shows the configuration of the video system.
Illumination light supplied from the light source 1 is applied to the subject 3 via the video module 2. The light source 1 is provided with a wavelength selection filter 8 that is appropriately inserted in the illumination optical path to generate illumination light having a wavelength distribution characteristic suitable for cell observation. When the illumination light in the visible wavelength range is irradiated onto the subject, the short wavelength light belonging to the blue wavelength region reaches only the surface layer of the living tissue. By utilizing this fact, it is possible to acquire information specialized for epithelial cells of living tissue.

  In addition, light in the vicinity of 500 nm belonging to the green wavelength region in the visible wavelength range has a property of reaching a portion slightly deeper than the surface layer of the living tissue, and has a long wavelength belonging to the red wavelength region in the visible wavelength range. Light has the property of reaching relatively deep parts of living tissue.

  The image of the subject is formed on the image pickup surface of the image pickup device by the objective optical system of the enlarged video module 2, converted into an electric signal, and sent to the image processing device 4. When processing image information in the visible wavelength range, the luminance information of the subject is extracted from the green wavelength component. This is in order to approach an image obtained through human eyes. Image information processed by the image processing device 4 is displayed on the TV monitor 5.

  Now, when white light, which is a mixture of three colors of red, green, and blue, is illuminated against blue stained cells, the stained part becomes blue, and the unstained part reflects the color of the illumination light. Becomes white. FIG. 4 shows the wavelength distribution characteristics of the cell image captured by the video module. In the figure, the vertical axis represents light intensity (unit: arbitrary unit), and the horizontal axis represents wavelength (unit: nm). The unstained portion has no absorption at a specific wavelength as shown by the solid line, and has a substantially flat wavelength distribution characteristic. As shown by the broken line, the blue-stained portion has a wavelength distribution characteristic in which the red component light is absorbed and the intensity is reduced.

  Thus, in the image obtained through the video module, the contrast between the background (the part that is not stained and white) and the cell nucleus and cell wall (the part that becomes stained and blue) is on the long wavelength side of the visible wavelength range such as red light. It can be seen that it is obtained by the difference in absorption characteristics.

  In addition, as shown in FIG. 1, the epithelial cells have a layered structure in the vertical direction, and the image of the cell layer other than the depth of interest overlaps the background, or the image of the substantial tissue located in the lower layer. If the image overlaps the background, the contrast of the image decreases. Compared with the cell nucleus, the cell wall is difficult to be stained. Therefore, when such image noise is superimposed on the background, the image as shown in FIG. 6 is obtained and it becomes difficult to identify the cell wall.

  In order to remove the image noise that overlaps the background, light that conveys information about the cell layer and the real tissue other than the depth of interest may be cut in the illumination optical path or in the objective optical system before the image sensor. . In the video system of the present embodiment, a filter for cutting a specific wavelength range is inserted in the illumination optical path to remove unnecessary wavelength components from the illumination light. In this case, it is only necessary to remove light on the long wavelength side of the visible wavelength range, such as mainly red light as an unnecessary wavelength component, but if all red light is cut off, it will not be dyed as a blue stained part. The wavelength component for obtaining the contrast with the portion is cut off, which is not preferable.

  Therefore, in this embodiment, a filter having spectral transmission characteristics shown in FIG. 7 is used as the wavelength selection filter 8 of the light source. In the figure, the vertical axis represents transmittance (unit: percent), the horizontal axis represents wavelength (unit: nm), and the spectral transmittance characteristics are indicated by solid lines. More specifically, among the illumination light in the blue wavelength region, the green wavelength region, and the red wavelength region, at least the illumination light in the red wavelength region is divided into two wavelength bands R1 and R2, and the wavelength band R1 close to the green wavelength region is obtained. This is a filter to be cut, and the wavelength band R1 is set to 600 nm to 700 nm, and the wavelength band R2 is set to 700 nm to 800 nm.

  By illuminating light with a wavelength band R1 close to the green wavelength region, the light that reaches the cell layer and the substantial tissue within the depth of field of the objective optical system other than the depth of interest is limited. Therefore, the depth of field of the objective optical system is substantially reduced, resolution in the depth direction is improved, and image overlap can be removed. On the other hand, the light in the wavelength band R2 contributes to obtaining the contrast between the cell nucleus and cell wall stained blue and the other portions not stained, so that information from an unnecessary depth is erased as shown in FIG. Thus, only the cell layer of interest can be clearly imaged. The characteristics shown in FIG. 7 can be realized by a dichroic filter or the like.

  In addition, a contrast agent can be used to emphasize only the cell nucleus. In this case, since the contrast agent absorbed in the cell nucleus is excited by the excitation light and emits fluorescence when returning to the ground state, only the cell nucleus can be accurately identified by observing this. In particular, a method for confirming the expression of a specific gene that appears when a normal contrast cell is transformed into a lesion such as cancer by injecting a gene contrast agent (such as GFP) into the cell as a gene marker that reacts to light, It is effective to use the video system of the present invention.

  In this method, signs of changes in genes in living cells appear just before the lesion changes, and genetic markers that have not had any effect on normal cells are expressed and weak against excitation light. Fluorescent light is emitted. For this reason, it is desirable that the video module used for such observation includes an ultra-sensitive camera.

The video system for observing fluorescence images of cell nuclei is preferably used in combination with a conventional endoscope. An example of such a combination is shown in FIG.
The video system for observing a fluorescent image is configured as a thin endoscope having an insertion portion 41.
The video module 42 of the fluorescent image observation video system is mounted on the end of the insertion portion 41. Reference numeral 43 denotes a conventional endoscope, and the treatment instrument insertion port 44 extends from the distal end of the conventional endoscope to the hand side (not shown). The conventional endoscope 43 also has an observation window 45 and illumination windows 46 and 47 at its ends.
The insertion part 41 of the video system for fluorescent image observation is inserted into the treatment instrument insertion port 44 from the hand side of the conventional endoscope 43 and comes out of the distal end side opening of the treatment instrument insertion port 44.
A conventional endoscope 43 into which a fluorescent image observation video system is inserted is inserted into a body to be observed. In order to guide the video module 42 of the video system for fluorescent image observation to the target observation site, the conventional endoscope 43 sees that the insertion portion 41 of the video system for fluorescent image observation protrudes from the treatment instrument insertion port 44. Can do.
Further, by displaying the image of the conventional endoscope and the fluorescent image of the video module side by side on the TV monitor 5, the state of the living tissue around the cell nucleus can be grasped while observing the fluorescent image of the cell nucleus. And it is possible to observe safely.

  For example, when a contrast agent of a type that mainly absorbs light having a wavelength shorter than 480 nm and emits fluorescence having a wavelength longer than 470 nm is used, a filter having spectral transmission characteristics shown in FIG. Is preferred. In the figure, the vertical axis represents transmittance (unit: percent), the horizontal axis represents wavelength (unit: nm), and the spectral transmittance characteristics are indicated by solid lines.

  More specifically, the filter divides the illumination light in the blue wavelength region into two wavelength bands B1 and B2, and cuts the wavelength band B1 close to the green wavelength region. The wavelength band B1 is 450 nm to 500 nm, and the wavelength band B2 Is set to 350 nm to 450 nm. The objective optical system is provided with a filter that transmits light having a wavelength longer than 470 nm and cuts light having a wavelength shorter than 470 nm. The excitation light can be cut to obtain a fluorescence image of the cell nucleus. By cutting and illuminating the light in the wavelength band B1 where the wavelength of the excitation light and the fluorescence wavelength overlap, it is possible to take out very weak fluorescence and image it clearly without being affected by the excitation light. .

  Further, a filter for reducing the intensity of light in the green wavelength region or the red wavelength region may be added to the wavelength selection filter 8 of the light source. In this way, it is possible to obtain a normal observation image of a living tissue with a conventional endoscope while preventing unnecessary image noise from overlapping the background of the fluorescence image of the cell nucleus.

Next, an illumination method suitable for cell observation in a living body will be described with reference to FIG.
At the distal end of the endoscope, a distal end portion of an illuminating device that irradiates illumination light toward the subject and a distal end portion of an objective optical system that forms an image of light from the subject on the imaging surface of the image sensor are arranged. Suppose that the central axis of the illumination field L and the central axis of the visual field F are separated by a distance d. When observing a living tissue using an endoscope, the tip of the endoscope is arranged so as to be close to and facing the living tissue, and among the epithelial cell layer and the substantial tissue layer constituting the living tissue, The distance X between the site of interest and the distal end surface of the endoscope is adjusted so that the site of interest falls within the depth of field range of the objective optical system. Here, the distance between the epithelial cell layer and the endoscope front end surface is X1, and the distance between the substantial tissue layer and the endoscope front end surface is X2.

  In a conventional endoscope, a parenchyma separated by a distance X2 is observed in the field of view F2 of the objective optical system. At this time, in order to ensure uniform brightness in the visual field F2, the distance d between the central axis of the illumination field L and the central axis of the visual field F at the distal end of the endoscope is distributed forward by a distance X2. Is determined to include the field of view F2. The distance X2 is several millimeters to several tens of millimeters.

  On the other hand, in the magnifying endoscope, epithelial cells separated by a distance X1 are observed in the visual field F1 of the objective optical system. The distance X1 is from zero to a few microns. As described above, in a state where the distance between the endoscope front end surface and the subject is hardly obtained, even if the distance d between the central axis of the illumination field L and the central axis of the visual field F at the distal end of the endoscope is reduced, the distance X1 is set. The illumination field L1a distributed only in the forward direction cannot include the visual field F1. That is, it can be seen that the conventional illumination method cannot ensure uniform brightness in the field of view F1 of the objective optical system. Therefore, in the present invention, an illumination method is employed in which uniform brightness is obtained in the field of view F1 by using a substantial tissue layer positioned further forward than the depth of field range of the objective optical system.

  In FIG. 13, there is an observation object at a distance X1 from the distal end of the endoscope, and a substantial tissue layer is present at a distance X2. The illumination light irradiated from the tip of the endoscope passes through the illumination field L1a and reaches the substantial tissue layer. The parenchymal tissue layer scatters illumination light as a reflection / scattering surface. Considering that the distribution of illumination light emitted from the tip of the endoscope follows a Gaussian distribution, 1 / e (where e is the natural logarithm) with respect to the intensity of illumination light when the light distribution angle is zero degrees The light distribution angle ω that is the bottom is defined as the effective illumination light distribution angle.

  The illumination light emitted from the tip of the endoscope propagates through the living tissue at a light distribution angle ω1 ′ and reaches the substantial tissue layer. The illumination light reflected / scattered by the parenchymal tissue layer propagates through the living tissue toward the epithelial cells at a light distribution angle ω2 ′, and includes the field of view F1 of the objective optical system at a distance X1 from the distal end of the endoscope. Teruno L1b is formed. As a result, uniform brightness can be secured in the field of view F1 of the objective optical system.

Here, ω1 ′ and ω2 ′ are light distribution angles in the living tissue, and the following formula is used for conversion to the light distribution angle in the air.
sinω1 = 1.33 × sinω1 '
sinω2 = 1.33 × sinω2 '
Since the parenchymal tissue layer is outside the range of the depth of field of the objective optical system, the light reflected and scattered by the parenchymal tissue layer is not imaged, and only the illumination effect on the epithelial cells can be obtained. Further, it is desirable that the following condition is satisfied for the distance d between the central axis of the illumination field L and the central axis of the visual field F at the distal end of the endoscope.

1 ≦ log (d / (X1 × tanω)) ≦ 3 (10)
If the upper limit of this conditional expression is exceeded, uniform brightness cannot be secured within the field of view of the objective optical system. If the lower limit of this conditional expression is exceeded, it becomes difficult to dispose the distal end portion of the illumination device and the distal end portion of the objective optical system at the distal end of the endoscope while keeping the distal end outer diameter of the endoscope thin.

Furthermore, it is desirable to satisfy the following conditions.
5 ≦ d / (X2 × tanω) ≦ 30 (12)
If the upper limit or lower limit of this conditional expression is exceeded, uniform brightness cannot be secured within the field of view of the objective optical system.

  Further, the distance X1 from the distal end surface of the endoscope to the in-focus position of the objective optical system and the distance X2 from the distal end surface of the endoscope to the reflection / scattering surface such as the substantial tissue layer satisfy the following relationship. desirable.

0.5 ≦ log (X2 / X1) (11)
When the value is smaller than the lower limit of this conditional expression, the image of the substantial tissue layer is reflected in the field of view and the image quality is deteriorated.

Table 5 shows specifications of examples of the illumination method of the present invention, and Table 6 shows values of conditional expressions.
Table 5
Item Symbol Unit Example 1 Example 2
Scatterer distance X2 [mm] 0.1 0.1
Objective focusing distance X1 [mm] 0.015 0.002
Illumination parallax d [mm] 0.8 1
Lighting distribution angle ω [deg] 35 35

Table 6
No. Conditional expression Example 1 Example 2
10 1 ≦ log (d / (X1 × tanω)) ≦ 3 1.88 2.85
11 0.5 ≦ log (X2 / X1) 0.82 1.7
12 5 ≦ d / (X2 × tanω) ≦ 30 11.4 14.3
Next, a method for determining the presence / absence of cell abnormality (for example, whether the cell is cancerous) from the enlarged cell image will be described.

  FIG. 5 shows a stained cell image magnified and observed in Example 1. The video module used in the enlarged video system is set to a magnification at which several tens to several hundreds of nuclei can be observed on the monitor screen. For example, displaying tens to hundreds of cell nuclei on the monitor screen and evaluating the density of cells within the observation field based on the cell nucleus interval, etc., to determine the presence or absence of cell abnormalities Can do. Cell density can be statistically analyzed by comparison with normal sample data.

Such magnified video systems are set up to meet the resolution and field of view sufficient to observe the nucleus.
Increase the observation magnification of the video module, display several cell nuclei on the monitor screen, obtain the cell size from the number of nuclei observed in the unit area, and observe the shape of the cell nuclei. The presence or absence of abnormalities can also be evaluated. For example, since cancerous cells have unique characteristics such as enlargement or deformation of the cells themselves, it is possible to determine whether the cells are cancerous by evaluating the size and shape of the cell nucleus. .

  FIG. 8 shows the nuclei and cell walls magnified and observed in Example 2. The magnification video system is set to a magnification at which several nuclei can be observed on the monitor screen. From the cell wall area S and the nucleus area S ′, the ratio of nuclei in the cell can be determined, and the presence or absence of abnormality can be evaluated from the ratio. Such a magnified video system is set up to provide sufficient resolution and contrast to observe not only the nucleus but also the cell wall.

An example of a series of procedures for in vivo cell observation described above is shown in the flow of FIG.
When it is conceivable to select multiple wavelength characteristics of illumination light depending on the part to be observed and the type of dye to be selected, a system that filters a specific wavelength band from a white light source as described above is versatile. Excellent in terms. On the other hand, when the wavelength characteristics of the illumination light can be limited and used in advance, the configuration can be further simplified by making the illumination light monochromatic, for example.

  An example of an imaging system specialized for observation at a specific wavelength is shown in FIG. Since the video module of the present invention has a very short observation distance, the light source 17 can be composed of a single color and low output, such as an LED. The LED light source can be mounted on the endoscope body. Moreover, the fiber for illumination transmission can be omitted by arranging the LED light source at the tip. Since the observation system 11 only needs to correct spherical aberration with a single color, the optical system 13 can also be simplified. For example, it is possible to arrange a single lens using an aspherical surface in front of the stop 14 or to configure with several spherical lenses instead of an aspherical surface.

  The video module thus reduced in size and simplified can increase the degree of freedom of layout when mounted on a medical product such as an endoscope. For example, in a flexible-type insertion device, a catheter or laser probe is used. It can be combined with a treatment tool. In addition, a rigid type in-body insertion device can take a compact form such as a pencil type or a capsule type by wirelessly transmitting video information.

It is a figure explaining the observation principle of the biological tissue by the conventional endoscope. It is a figure explaining the observation principle of the sample by a microscope. It is a block diagram of the video system of this invention. It is a figure which shows the wavelength distribution characteristic of the image of the cell imaged with the video module of this invention. It is a figure which shows the dye | stained cell image enlargedly observed by the Example of this invention. It is a figure which shows an image when the cell of a lower layer has overlapped with the background. It is a figure which shows the spectral transmission characteristic of the wavelength selection filter used for the Example of this invention. It is a figure which shows the image which erase | eliminated the information of the unnecessary depth with respect to the image of FIG. It is a figure which shows the spectral transmission characteristic of another wavelength selection filter used for the Example of this invention. It is a figure which shows the example of the imaging system specialized in the observation in a specific wavelength. It is lens sectional drawing of Example 1 of this invention. It is lens sectional drawing of Example 2 of this invention. It is a figure which shows the illumination method suitable for the cell observation in a biological body. It is a flow which shows the procedure of in-vivo cell observation by this invention. It is a figure which shows a mode that the video system for fluorescence image observation of the cell nucleus of this invention is used in combination with the conventional endoscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 17 Light source 2 Video module 3 Subject 4 Image processing apparatus 5 TV monitor 8 Wavelength selection filter 11 Observation system 13 Optical system 14 Aperture 41 Insertion part 42 Video module 43 Endoscope 44 Treatment tool insertion port 45 Observation windows 46 and 47 Illumination Window 101 Objective lens group 102 Objective frame 103 Brightness stop 104 Cover glass 105 Imaging element 106 Imaging frame 107 Distance 108 Tip hard part 109 Intermediate member 110 Outer surface part 111 Fibers for illumination 112a and 112b Distance adjustment parts L1a, L1b, and L2 F1, F2 field of view

Claims (4)

An endoscope provided with an observation device and an illumination device for observing living tissue ,
The observation apparatus includes an objective optical system,
The observation device and the lighting device, when the focus position of the objective optical system is positioned on the upper layer tissue of the living body tissue, on the upper layer tissue from the distal end of the endoscope with the objective optical system of the observation field of view and illumination field of the illumination device to be illuminated are separated, and the light directed toward the upper layer tissue from the light transmittance is lower underlying tissue as compared to the upper layer tissue after passing through the upper layer tissue from the lighting device, as you form illumination field involving observation field of view of the objective optical system, an endoscope, characterized in that it is arranged. An endoscope for observing living tissue, including a video module having an objective optical system with an imaging magnification greater than 1.
The endoscope includes a lighting device,
The video module and the lighting device, when the focus position of the video module is positioned on the upper layer tissue of the living body tissue, is irradiated on the upper layer tissue from the distal end side of the observation field of view with the endoscope of the video module that a do not overlap the illumination field of the illumination device, and light directed toward the upper layer tissue from the light transmittance is lower underlying tissue as compared to the upper layer tissue after passing through the upper layer tissue from the lighting device, the so as to form a illumination field involving observation field of view of the video module, an endoscope, characterized in that it is placed. A video system for observing a living tissue , comprising a video module having an objective optical system having an imaging magnification greater than 1 and an illumination optical system, and a light source for supplying illumination light,
The video module and the illumination device are irradiated onto the upper layer tissue from the observation field of view of the video module and the distal end side of the endoscope when the in-focus position of the video module is located in the upper layer tissue of the living tissue. The illumination field of the illuminating device does not overlap the light field, and after passing through the upper layer tissue from the illuminating device, light directed from the lower layer tissue to the upper layer tissue having low light transmittance as compared with the upper layer tissue, Arranged to form an illumination field including the viewing field of the video module,
The light source has a wavelength close to the green wavelength region by dividing the illumination light in the blue wavelength region or the red wavelength region into two wavelength bands T1 and T2 out of the illumination light in the blue wavelength region, the green wavelength region, and the red wavelength region. A video system, characterized in that wavelength band selection means for blocking the band T1 is provided. The video system according to claim 3 , wherein the wavelength band T1 is 600 nm to 700 nm.