JP2012024146A - Polarization image measurement display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarization image measurement display system capable of identifiably displaying appearing tissues from an affected part or the like by obtaining a polarization property image and assisting a doctor's diagnosis.SOLUTION: The polarization image measurement display system includes: an irradiation part for successively irradiating a subject with many kinds of polarized light different in polarization; an image pickup part for successively picking up images of reflection light from the subject for every irradiation with the polarized light, and outputting the light intensity image information; a polarization conversion processing part for converting a plurality of light intensity image information into phase difference image information by polarization property of phase difference by performing polarization conversion processing to the light intensity image information; an emphasis polarization property image forming part for performing to phase different image information emphasis processing to display with emphasis an area at prescribed angle of phase different input from outside and obtaining emphasis phase difference image information; a display conversion processing part for converting the emphasis phase difference image information into display emphasis phase difference image information so as to visualize and display the emphasis phase difference image information; and a display part for displaying a display emphasis phase difference image corresponding to the display emphasis phase difference image information on the basis of the display emphasis phase difference image information.

Description

  The present invention relates to a polarization image measurement and display system, and more specifically, a polarization image that can measure a polarization image of a surface layer of a predetermined part of a living body and identify an exposed tissue from a lesion or the like, in particular, a predetermined polarization characteristic. The present invention relates to a polarization image measurement and display system that can display an exposed tissue from a lesion or the like in an identifiable manner using a polarization image measurement device that can obtain a polarization characteristic image according to the above.

  Conventionally, an optical diagnostic system such as an endoscope or an optical microscope has been used for diagnosing whether there is a lesion in a living body and how much the lesion has progressed. In these diagnostic systems, a part of the living body is irradiated with light and the reflected light is imaged, and changes in the color, brightness, structure, etc. of the living body surface are observed. Is diagnosed. In such an optical system of a diagnostic system, not only natural light for normal observation but also polarized light can be used to capture changes in normal and diseased areas from the characteristics of biological anisotropy. A technique for increasing the accuracy has been proposed (see Patent Documents 1, 2, and 3).

  Patent Document 1 of the present applicant's application uses, as an example, polarized light, and the ratio of non-polarized light of the return light that returns from the digestive organ, particularly the mucosal layer having polarization anisotropy of the stomach wall, that is, It is disclosed that by calculating the thickness of the mucosal layer based on the degree of polarization of the return light, it is possible to diagnose the degree of cancer invasion by detecting the change in the thickness of the mucosal layer of the stomach wall. Yes.

  In addition, Patent Document 2 discloses an image of backscattered light when illumination light having parallel polarization is irradiated on a region of interest that is a local region where high-magnification observation is performed by using polarized light. Using the image of the backscattered light when irradiated with illumination light having vertically polarized light, an enlarged observation image is obtained while removing multiple scattered light from the deep layer at the site of interest. It is disclosed that a polarized image signal is obtained by differential processing, an enlarged observation image is obtained based on the obtained polarized image signal, and displayed on a monitor.

  Further, in Patent Document 3, it becomes noise when observing a blood vessel image in fat by using polarized light when recognizing the position of a blood vessel distributed in fat using near infrared light. It is disclosed that by cutting backscattered light on the fat surface, it is possible to prevent halation due to light reflected on the fat surface and to accurately recognize the position of blood vessels distributed in the fat.

JP 2009-240676 A JP 2006-325993 A JP 2007-282965 A

  However, as an important criterion in diagnosing intramucosal cancer (m cancer), whether the lesion is cancer or not, or whether it is intramucosal cancer or not, for example, submucosal invasive cancer It is important to distinguish whether it is (sm cancer). Therefore, it is determined whether or not there is a mucosal muscle plate, that is, it exists normally. However, the technique described in Patent Document 1 described above shows that there is a possibility of diagnosing the degree of cancer invasion by changing the thickness of the mucosal layer of the stomach wall. However, there is no criteria for distinguishing between intramucosal cancer and submucosal invasive cancer, and polarized images that enable such judgment are not shown. There was a problem that could not be obtained.

  Further, the methods disclosed in Patent Documents 2 and 3 can display a magnified observation image by using polarized light, and can accurately recognize the position of a blood vessel distributed in fat. Therefore, the accuracy of living body observation can be improved, but the purpose is to remove the multiple scattered light from the deep layer in the region of interest, and the purpose is to prevent halation due to surface reflected light. Because the purpose is not to detect the anisotropy of the tumor, it is necessary to measure polarized images that can determine whether the lesion is cancer or not, and whether it is intramucosal cancer or submucosal invasive cancer. There was a problem that could not.

  An object of the present invention is to solve the above-mentioned problems of the prior art, obtain a polarization characteristic image with a predetermined polarization characteristic, and display an exposed tissue from a lesion or the like in an identifiable manner. An object of the present invention is to provide a polarization image measurement and display system that can assist in identifying a tissue exposed from a lesion or the like by observing a polarization characteristic image and diagnosing the degree of invasion of cancer.

In order to achieve the above object, the present invention includes an irradiation unit that sequentially irradiates a subject with a plurality of polarized lights having different polarization states;
An imaging unit that sequentially images reflected light from the subject each time the polarized light having a different polarization state is irradiated from the irradiation unit to the subject, and outputs the light intensity image information;
Polarization conversion processing is performed on a plurality of light intensity image information of reflected light from a subject of a plurality of polarized lights having different polarization states output from the imaging unit, and converted into phase difference image information based on polarization characteristics of a phase difference. A polarization conversion processing unit to convert;
Emphasized polarization characteristics to obtain enhanced phase difference image information by performing enhancement processing for emphasizing a region of a predetermined phase difference angle inputted from the outside with respect to the phase difference image information obtained by the deflection conversion processing unit An image forming unit;
A display conversion processing unit that converts the enhanced phase difference image information obtained by the enhanced polarization characteristic image forming unit into display enhanced phase difference image information for visualization and display;
A display unit that displays a display enhanced phase difference image corresponding to the display enhanced phase difference image information based on the display enhanced phase difference image information obtained by the display conversion processing unit. A polarization image measurement display system is provided.

  Here, it is preferable that the enhanced polarization characteristic image forming unit performs an enhancement process of expanding a dynamic range of the predetermined phase difference angle region and compressing a dynamic range of the other angle region. .

  The emphasized polarization characteristic image forming unit removes regions other than the predetermined phase difference angle region and performs an emphasis process for displaying only the predetermined phase difference angle region in a pseudo color display. It is preferable.

  Further, it is preferable that the emphasized polarization characteristic image forming unit performs an emphasis process for displaying only the region having the predetermined phase difference angle in pseudo color and displaying the other angle region in black and white.

  In addition, it is preferable that the enhanced polarization characteristic image forming unit performs an enhancement process in which a region including the region having the predetermined phase difference angle is outlined in black and white.

  Further, it is preferable that the emphasized polarization characteristic image forming unit performs an emphasis process in which a region including the region having the predetermined phase difference angle is surrounded by a line.

  According to the present invention, it is possible to obtain a polarization characteristic image having a predetermined polarization characteristic and display the exposed tissue from the lesioned part so as to be identifiable. It is possible to identify the exposed tissue and diagnose the invasion degree of intramucosal cancer.

In addition, according to the present invention, an endoscopic diagnosis apparatus and a laparoscopic navigation apparatus that can display an exposed tissue from a lesion or the like in an identifiable manner and can be used for endoscopic surgery, laparoscopic surgery, and the like. Applicable to.
Furthermore, according to the present invention, it is possible to easily and accurately perform endoscopy and diagnosis, and to provide a polarization image that helps to easily and accurately perform endoscopic surgery, laparoscopic surgery, and the like. Can do.

  In particular, according to the present invention, whether a lesion (lesion) at a predetermined site such as a digestive organ of a living body is cancerous or not, or whether it is intramucosal cancer or not, for example, submucosal invasion cancer Imaging and identifying "the presence or absence of collagen fibers appearing in the mucosal layer" corresponding to "the presence or absence of mucosal muscle plate" that is the judgment criterion of the discrimination by polarization measurement And a polarized image showing them can be obtained.

  Further, according to the present invention, “presence / absence of collagen fibers appearing in the mucosal layer”, which is a criterion for judging cancer, intramucosal cancer, submucosal invasive cancer, etc., is displayed on a display means such as a monitor in pseudo color. Can be displayed.

  Furthermore, according to the present invention, by highlighting a region of interest such as collagen fibers in a polarization characteristic image, a doctor can easily identify collagen fibers that appear in the mucosal layer, that is, lesions. It becomes like this. That is, diagnosis accuracy can be improved by supporting diagnosis.

It is a block diagram which shows schematic structure of one Embodiment of the polarization image measurement display system of this invention. It is a schematic diagram of one Embodiment of the polarization imaging system of the polarization image measurement display system shown in FIG. It is a schematic block diagram of other embodiment of the polarization imaging system of the polarization image measurement display system shown in FIG. (A) is a schematic block diagram of other embodiment of the polarization imaging system of the polarization image measurement display system shown in FIG. 1, (b) is a patterning polarization / wave plate used for the polarization imaging system of (a). It is an expansion schematic diagram which expands and shows the element for 1 pixel of. (A) is a schematic block diagram of other embodiment of the polarization imaging system of the polarization image measurement display system shown in FIG. 1, (b) is a patterning polarization / wave plate used for the polarization imaging system of (a). It is an expansion schematic diagram which expands and shows the element for 1 pixel of. It is a schematic block diagram of other embodiment of the polarization imaging system of the polarization image measurement display system shown in FIG. It is explanatory drawing of the row Mueller measuring system for demonstrating the Mueller image conversion algorithm used for this invention. It is a schematic diagram of one Embodiment of the polarization conversion process part of the polarization image measurement display system shown in FIG. 1, and its polarization variable separation process part. (A) And (b) is a schematic block diagram of one Embodiment of the biological observation model at the time of carrying out variable separation by the polarization variable separation process part shown in FIG. 8, respectively. (A) is a schematic configuration schematic diagram of the vicinity of the surface layer of a normal living body, (b) is a schematic configuration schematic diagram of the vicinity of the surface layer of a living body in which intramucosal cancer has occurred, and (c) is a submucosal layer. It is a schematic structure schematic diagram near the surface layer of a living body that has progressed to invasive cancer. It is a flowchart which shows an example of the polarization image display method implemented with the polarization image measurement display system of this invention. It is a color image of an example of the cross section of a large intestine normal part. FIG. 13 is a pathologically stained specimen of a normal part of the large intestine shown in FIG. 12. 13 is a light intensity image of a normal part of the large intestine shown in FIG. (A) to (F) capture a plurality of light intensity polarization images by sequentially irradiating the surface of the cross-section of the normal colon shown in FIG. 12 with a plurality of polarized lights having different polarization characteristics. Light intensity polarization image created by performing polarization conversion processing and display conversion processing on polarization image, depolarization degree, polarization degree of light, phase difference, phase difference direction, absorption direction, optical rotation polarization characteristics image , (G) are pseudo color palettes applied to these polarization characteristic images. It is an example of a parameter setting table.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a polarization image measurement device and a polarization image measurement display system according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a schematic block diagram showing a schematic configuration of an embodiment of a polarized image measurement display system of the present invention.
A polarized image measurement display system 10 of this embodiment shown in FIG. 1 inspects a predetermined part of a living body (subject), for example, a body cavity such as a digestive organ of a human body, an abdomen of a human body, etc. Applicable to endoscopes and laparoscopes used for observing, diagnosing, performing surgery and treatment, etc., and used for endoscope diagnostic devices, laparoscopic navigation devices, etc. Obtain a predetermined polarization characteristic, that is, a polarization characteristic image based on a polarization variable, to distinguish the exposed tissue that appears on the surface layer of the part from the surface layer tissue, and visualize the displayed tissue so that it can be distinguished from the surface tissue. To do.

The polarization image measurement and display system 10 in the illustrated example irradiates a predetermined part of a living body with irradiation light (polarized light) having a plurality of different polarization states, respectively, and a plurality of reflected light from a plurality of different polarization states from a surface layer of the predetermined part. A polarization imaging system 12 that captures a light intensity image and a polarization conversion process on a plurality of light intensity images in different polarization states to obtain polarization characteristic images (a plurality of polarization characteristic images each having a different polarization characteristic) with predetermined polarization characteristics A polarization conversion processing unit 14; a display conversion processing unit 16 that converts the polarization characteristic image into a display polarization characteristic image for visualizing and displaying the exposed tissue distinguishably from the surface tissue; and a display polarization characteristic image. Display unit 18 for displaying normal color imaging system 20 for acquiring a normal color image of a predetermined part, and a polarization characteristic image for display to be displayed on top of each other or side by side. Having an image combining unit 22 for combining the two images, the.
Note that the polarization imaging system 12 and the polarization conversion processing unit 14 constitute a polarization image measurement device according to the present invention.

  The polarization imaging system 12 can measure not only conventional P / S polarized light but also a high-order polarization parameter (Mueller matrix) including a plurality of deflection characteristics (polarization variables), that is, photographing. It constitutes a Mueller imaging system that can measure the Mueller of the object, and a polarized light irradiation unit 24 that irradiates a predetermined part of a living body with irradiation light of a plurality of different polarization states from its surface layer, and polarized light with different polarization states is irradiated with polarized light Each time the living body is irradiated from the unit 24, the reflected light of the plurality of polarization states is sequentially received from the surface layer of the predetermined portion irradiated by the irradiation light of the plurality of polarization states, and a plurality of light intensity images of the surface layer of the predetermined portion And an image pickup unit 26 for picking up images.

  In the present invention, the polarization imaging system 12 may be any imaging system as long as it can constitute such a Mueller imaging system. Various types can be used.

In FIG. 2, the schematic diagram of one Embodiment of the polarization imaging system of this invention is shown.
The polarization imaging system 12a shown in the figure is used as the polarization imaging system 12 shown in FIG. 1 and forms an optical system of an Azzam type double phaser type Mueller matrix polarimeter. Imaging is performed by receiving, as detection light, a polarized light irradiation unit 24a that irradiates a human body abdomen A, which is a predetermined part of a target living body, with irradiation light in a predetermined polarization state, and reflected light in a predetermined polarization state reflected from the human body abdomen A as detection light. An imaging unit 26a.

  The polarized light irradiation unit 24a is disposed on the light source 34, the polarizing plate 36a that is the first polarizer of the present invention fixedly disposed on the human body abdomen A side from the light source 34, and the human body abdomen A side, and is rotated every predetermined angle. An irradiation-side first polarizing filter section 40a that includes a rotation phase difference plate 38a that is a first phase difference providing unit of the present invention and that sequentially transmits only irradiation light in one polarization state among a plurality of polarization states. Have

  The imaging unit 26a is arranged on the CCD camera 42, the polarizing plate 36b, which is the second polarizer of the present invention fixedly arranged on the human body abdomen A side from the camera 42, and the human body abdomen A side. Only the reflected light in one polarization state corresponding to one polarization state of the irradiation light transmitted through the first polarizing filter section 40a. And a second polarizing filter section 40b on the reflection side that sequentially transmits the light.

  The light source 34 used for the polarized light irradiation unit 24a is not particularly limited as long as it can emit light of a predetermined wavelength that can illuminate the human abdomen A so that it can be imaged. For example, a laser or LED that emits a laser beam of a predetermined narrow band wavelength Etc., white lamps such as xenon lamps, fluorescent lamps, mercury lamps, etc., white LEDs or white lasers composed of LEDs or lasers of three primary colors such as RGB, pseudo-white composed of lasers and phosphors of a predetermined wavelength A laser or the like can be used. In the case of using a white light or a white LED, it is necessary to use a color filter that transmits a predetermined narrow band wavelength or a so-called band pass filter.

  Here, the predetermined narrow-band wavelength of the irradiation light is not particularly limited, but may be a visible region such as 400 nm to 700 nm or an infrared region of 700 nm to 1300 nm. The band is, for example, 5 nm to 50 nm, preferably 10 nm to 20 nm.

  The camera 42 acquires light intensity image information by polarized light of the human abdomen A as digital image information, and for example, a high pixel density camera including an image sensor such as a CCD or a CMOS can be used. The number of pixels is not particularly limited, but in order to obtain a high-definition polarized image, it is preferably 200,000 pixels or more, more preferably 1 million pixels or more. The upper limit of the number of pixels is not particularly limited, but may be determined according to the number of pixels of a CCD of a camera of the imaging unit 26a described later or a CCD 56 described later.

  The polarizing plates 36a and 36b of the first and second polarizing filter sections 40a and 40b are used as a polarizer and an analyzer, respectively. The same polarizing plate is used, and the optical axis of the light emitted from the light source 34 is used. It is fixed to the vertical. For example, the light emitted from the light source 34 is linearly polarized by the polarizing plate 36a. The reflected light that has passed through the rotational retardation plate 38b is linearly polarized by the polarizing plate 36b.

  In addition, the rotating phase difference plates 38a and 38b of the first and second polarizing filter sections 40a and 40b are, for example, rotating disk-shaped λ / 4 wavelength plates, that is, λ / 4 wavelength plates are used as optical axes. It can be configured by rotating at predetermined angles around the optical axis in a vertical plane. For example, light that has passed through the rotational phase difference plate 38a becomes linearly polarized light or circular (elliptical) polarized light, and light reflected by the human abdomen A also becomes linearly polarized light or circular (elliptical) polarized light. Note that the two λ / 4 wave plates serving as the rotational phase difference plates 38a and 38b are rotated by a predetermined angle in a state shifted by a predetermined angle around the optical axis so as to have a predetermined phase difference perpendicular to the optical axis. The

  The mechanism for rotationally driving the rotational phase difference plates 38a and 38b is not particularly limited, and a known rotational driving mechanism that rotates while holding the outer periphery of the disk constituting the rotational phase difference plates 38a and 38b. Can be used.

  Since the first polarization filter unit 40a of the polarization irradiation unit 24a of the polarization imaging system 12a and the second polarization filter unit 40b of the imaging unit 26a need to be accurately maintained in their respective predetermined polarization states, both Must be accurately aligned.

  Since the polarization imaging system 12a needs to rotationally drive the rotation phase difference plates 38a and 38b, and the apparatus becomes large, the polarized light irradiation unit 24a and the imaging unit 26a need to be installed outside the abdomen A of the human body. However, the polarization characteristic (polarization variable) is perfect, and can be preferably applied to a laparoscope, and can be preferably used for a laparoscopic navigation apparatus. The rotational retardation plates 38a and 38b are not limited to λ / 4 plates, and λ / 2 plates or other retardation plates may be used.

  Here, for example, the polarization imaging system 12a according to the illustrated embodiment constitutes a Mueller imaging system, and obtains a light intensity polarization image for obtaining a 4 rows × 4 columns Mueller matrix of the imaging target (sample) M. It is.

  Therefore, in the present embodiment, in order to obtain all the polarization characteristics included in the Mueller matrix, that is, all 16 (= 4 × 4) polarization variables, details will be described later, but at least 16 sheets having different polarization states from each other. It is necessary to obtain a light intensity polarization image of the. That is, at least four types of polarization states of incident light emitted from the first polarizing filter unit 40a and incident on the abdomen A of the human body are different from each other, reflected from the abdomen A of the human body, and emitted from the second polarizing filter unit 40b. It is necessary to rotate the rotational phase difference plates 38a and 38b so that the detection light has at least four different polarization states, and the combination has at least 16 different polarization states.

For example, in the polarization imaging system 12a, the λ / 4 wavelength plate of the rotational phase difference plate 38a of the first polarizing filter unit 40a is set to the polarization state of light to be described later so that the polarization state of incident light is at least four different from each other. Is rotated so that the Stokes parameters S ₀ , S ₁ , S ₂ and S _{3 of the} incident light representing each other are different from each other, and the λ / 4 wavelength plate of the rotational retardation plate 38b of the second polarizing filter unit 40b is for each of the Stokes parameters _{S 0,} S 1, _{S 2} and _{S 3,} so that the polarization state of the emitted light is at least four mutually different, for example, the Stokes parameters of the emitted light _{S 0,} S 1, _{S 2} and while rotating the S ₃ to be different from each other, the imaging unit 26 captures more than 16 times, 16 frames (pictures) or more optical intensity polarized image, i.e. more than 16 frames Light intensity polarization image information needs to be acquired. In this case, resist processing is preferably performed.

The Stokes parameters S ₀ , S ₁ , S ₂ , and S ₃ are the polarizations of the entire intensity of polarization (sum of vertical and horizontal polarization vectors) and vertical and horizontal (horizontal and vertical directions), respectively. It can be said that the vector difference, the polarization vector difference between 45 and 135 degrees, and the difference between right circular polarization and left circular polarization.

In the present invention, Stokes parameters S ₀ , S ₁ , S ₂ , and S ₃ of incident light and outgoing light are obtained from light intensity polarization images of 16 frames (sheets) or more having different polarization states. The matrix may be obtained. However, if the calculation method is set in advance so as to directly obtain the Mueller matrix from the light intensity polarization images of 16 frames (sheets) or more having different polarization states, the Stokes of the incident light and the emitted light is set. The parameters S ₀ , S ₁ , S ₂ , and S ₃ are not necessarily obtained.

  In the present embodiment, when the polarization angle (rotation angle) of the λ / 4 wavelength plate that is the rotation phase difference plate 38a is θ, the polarization angle (rotation) of the λ / 4 wavelength plate that is the rotation phase difference plate 38b. The angle is preferably 5θ or more and an odd multiple of θ, preferably 5θ.

  For example, the rotation angle θ of the λ / 4 wavelength plate of the rotational retardation plate 38a of the first polarizing filter section 40a is changed by a predetermined angle from 0 ° to 180 °, for example, every 11.25 °, and the first While changing the rotation angle of the λ / 4 wavelength plate of the rotational retardation plate 38b of the two-polarization filter unit 40b by 5 times or more, that is, for each angle of 5θ or more, the imaging unit 26 is 16 (= 180 / 11.25). ) It is possible to obtain 16-frame light intensity polarization images.

  Although details will be described later, in the present invention, in the polarization imaging system 12a, the imaging unit 26 changes the polarization angle θ of the λ / 4 wavelength plate from 0 degrees to 180 degrees, for example, every 7.2 degrees. It is more preferable to take 25 (= 180 / 7.2) times and obtain 25 frames (sheets) of light intensity polarization image, that is, 25 frames of light intensity polarization image information.

  Note that the rotation method of the rotation phase difference plates 38a and 38b is not limited to this, and even one of the 16 polarization variables (elements) of the 4 × 4 Mueller matrix may be missing and cannot be obtained. Basically, any rotation method may be used as long as the polarization state of the incident light and the outgoing light can be changed into different polarization states including a circularly polarized light component and a linearly polarized light component and having a change in azimuth. However, all polarization variables are evenly modulated (for example, linearly polarized light ← → elliptically polarized light ← → circularly polarized light, the optical axis direction is 0 ° ← → 180 ° (= the entire surface of the Poincare sphere)), and the same condition is not overlapped. It is preferable to do. For example, if the rotation angle of the rotating phase plate 38a is 0 °, 90 °, 180 °, and 270 °, the circularly polarized components of 45 ° and 135 ° do not occur, and all polarization variables of 4 rows by 4 columns of the Mueller matrix. It is necessary to rotate the angle in between. Also, the optical axis has only two directions of 0 ° and 90 °, and if there is no 45 ° or 135 ° component between the azimuths, it is impossible to obtain all polarization variables of the Mueller matrix. It will be complete.

  If it is not necessary to obtain all the polarization characteristics (polarization variables) included in the Mueller matrix and only specific polarization characteristics (polarization variables) are required, the light intensity polarization image of at least 16 frames such as 25 frames. It is not necessary to acquire the light intensity polarization image of the required number of frames according to the required polarization characteristic (polarization variable). For example, when only the polarization state related to linear polarization becomes a problem, a light intensity polarization image of less than 16 frames, for example, only 12 frames may be acquired.

  The polarization imaging system 12a of the embodiment shown in FIG. 2 uses a rotating phase difference plate 38a as the first phase difference providing means of the present invention of the polarized light irradiation unit 24a, and the second phase difference of the present invention of the imaging unit 26a. Although the rotation phase difference plate 38b is used as the applying unit, the present invention is not limited to this, and for example, a phase difference sheet or two phase modulation elements may be used as the first phase difference applying unit. And as a 2nd phase difference provision means, you may use the patterning element affixed on two phase modulation elements, a polarizer sticking patterning element, or a polarizer and a phaser.

FIG. 3 shows an embodiment of a polarization imaging system using two phase modulation elements as the first and second phase difference providing units.
The polarization imaging system 12b shown in FIG. 3 uses the optical imaging system 12a shown in FIG. 2 except that two phase modulation elements 44a, 45a and 44b, 45b are used instead of the rotational phase difference plates 38a and 38b, respectively. Therefore, detailed description thereof is omitted.
The polarization imaging system 12b includes a polarization irradiation unit 24b and an imaging unit 26b. The polarization irradiation unit 24b includes a light source 34, a polarizing plate 36a, a first phase modulation element 44a, and a second phase modulation element 45a. The imaging unit 26b includes a first polarizing filter unit 46b including first and second phase modulation elements 44b and 45b and a polarizing plate 36b, and a camera 42.

The first and second phase modulation elements 44a and 45a used in the first polarization filter unit 46a of the polarized light irradiation unit 24b are the first and second phase modulation elements 44b used in the second polarization filter unit 46b of the imaging unit 26b. It has the same configuration as 45b. These phase modulation elements 44a, 44b, 45a and 45b have directionality in refractive index and cannot be changed with respect to the direction, but the height of the refractive index can be changed by being electrically driven. For example, when linearly polarized light enters, it is possible to pass only linearly polarized light by changing the refractive index height, or elliptically polarized light or circularly polarized light depending on the height of the vertical and horizontal refractive indexes. It is an element that can also pass (λ / 4). Examples of such phase modulation elements 44a, 44b, 45a, and 45b include a phase modulation element using a liquid crystal element and a commercially available phase modulation element (for example, manufactured by Meadowlark). it can.
By installing the second phase modulation elements 45a and 45b at 45 degrees with respect to the first phase modulation elements 44a and 44b (for example, arranged at 0 degree) (for example, arranged at 45 degrees), Circularly polarized light can be linearly polarized light, ellipticity of elliptically polarized light can be changed, and elliptically polarized light of various angles can be obtained. For example, when linearly polarized light in the direction of 45 ° is incident on the first phase modulation element 44a installed at 0 °, the phase difference (birefringence) of the phase modulation element 44a is 0 (= 0 °) In this case, the linearly polarized light is transmitted as it is without being changed. On the other hand, when the phase difference of the phase modulation element 44a is λ / 4 (= 90 ° = π / 2), the linearly polarized light has no influence. In response, it will come out as circularly polarized light.

For this reason, in the polarization imaging system 12b, the first phase modulation elements 44a and 44b and the second phase modulation elements 45a and 45b are combined and electrically modulated to drive the rotational phase difference plate 38a that rotates mechanically. The function similar to 38b can be exhibited. That is, the incident light realized by rotating the rotation phase difference plates 38a and 38b in the polarization imaging system 12a shown in FIG. 2 by combining the first phase modulation elements 44a and 44b with the second phase modulation elements 45a and 45b, respectively. The polarization state of the incident light, the polarization state of the incident light, and the polarization state of the same detection light can be achieved. Even in the incident light from the polarization irradiation unit 24b, in the detection light of the imaging unit 26b , The Stokes parameters S ₀ , S ₁ , S ₂ and S ₃ can be determined and set.

That is, the first phase modulation element 44a of the first polarization filter unit 46a of the polarized light irradiation unit 24b.
Is set such that the slow axis is 0 degree with respect to the slow axis of the polarizing plate 36a, that is, the angle of the axis (the direction in which the refractive index is high) is 0 °, The amount of polarization (vector), that is, the phase difference is set to Δ1 and Δ2, and the first phase modulation element 44b has a slow axis of 45 degrees with respect to the slow axis of the polarizing plate 36a, that is, the axis (refracted). The incident angle from the polarized light irradiating unit 24b is set so that the angle of the high-rate direction is 45 ° and the amount of polarized light in the oblique (left-right) direction, that is, the phase difference is Δ1 and Δ2. In light, Stokes parameters S ₀ , S ₁ , S _2, and S ₃ representing the polarization state of light, which will be described later, can be made different from each other.

On the other hand, for the second phase modulation elements 45a and 45b of the second polarizing filter section 46a of the imaging unit 26b, the angle of the axis (the direction in which the refractive index is high) of the second phase modulation element 45b is 0 °. Is set so that the phase difference is Δ1, Δ2, and the second phase modulation element 44a is set so that the angle of the axis (the direction in which the refractive index is high) is 45 °, and the phase difference is Δ1, By making Δ2, the Stokes parameters S ₀ , S ₁ , S ₂ and S ₃ can be made different from each other even in the detection light of the imaging unit 26b.

  Therefore, the polarization imaging system 12b of the present embodiment also constitutes a Mueller imaging system, and can obtain at least 16 light intensity images with polarized lights having different polarization states, and all 16 polarization variables included in the Mueller matrix. Can be obtained.

  Since this polarization imaging system 12b drives the phase modulation elements 44a, 44b, 45a and 45b, the polarization characteristic (polarization variable) is perfect, and the polarization shown in FIG. 1 which rotationally drives the rotation phase plates 38a and 38b. Since the apparatus can be downsized as compared with the imaging system 12a, the apparatus can be more suitably applied to a laparoscope and can be preferably incorporated into a laparoscopic navigation apparatus.

  In the example shown in FIGS. 2 and 3, the same polarizing filter unit is used for the polarized light irradiation unit 24 and the imaging unit 26. However, the present invention is not limited to this, and different polarizing filter units are used. Alternatively, different phase difference providing means may be used. For example, the polarization imaging unit may be configured by using the polarization irradiation unit 24a illustrated in FIG. 2 and the imaging unit 26b illustrated in FIG. 3, or conversely, the polarization irradiation unit 24b illustrated in FIG. A polarization imaging system may be configured using the imaging unit 26a.

  In the example shown in FIGS. 2 and 3, the polarized light irradiation unit 24 and the imaging unit 26 are disposed outside the living body, and are applied to a laparoscope or the like. An example applicable to the inside of a living body is shown.

FIG. 4A is a schematic diagram of one embodiment of a polarization imaging system applied to an endoscope, and FIG. 4B is a pattern polarization / wave plate for one pixel used in the polarization imaging system. It is an expansion schematic diagram which expands and shows this element.
The polarization imaging system 12c shown in FIG. 4A includes a polarization irradiation unit 24c and an imaging unit 26c. The polarization irradiation unit 24c includes a light source 34, a polarizing plate 36a, and first and second phase modulation elements 44a and 45a. A first polarizing filter unit 46 a and an optical probe 50 including an optical fiber 48, and the imaging unit 26 c is a second polarizing filter unit including a patterning polarization / wave plate 52 disposed in the optical probe 50. 54 and a CCD 56.
Here, since the light source 34 and the first polarizing filter unit 46a of the polarized light irradiation unit 24c have the same configuration as the polarization imaging system 12b shown in FIG. 3, detailed description thereof will be omitted.

  The optical fiber 48 functions as an optical transmission unit of the endoscope, guides irradiation light in a predetermined polarization state that has passed through the second polarizing filter unit 54 to the tip of the optical probe 50, and passes a predetermined part from the tip. Is irradiated to the surface layer of the digestive organ B such as the stomach, which is a predetermined part in the body cavity of the living body.

  The CCD 56 is a high pixel density image sensor that acquires light intensity image information by polarized light on the surface layer of the body cavity B as digital image information, but other image sensors such as a CMOS may be used.

  As shown in FIG. 4B, the patterned polarization / wavelength plate 52 disposed in the optical probe 50 includes a rectangular polarizing plate 55a composed of an array of four polarizers having different polarization states, and one of them. A plurality of rectangular polarizers and phase shifter patterning elements 53 each including a phase plate (wave plate) 55b attached to one polarizer are arranged in an array by the number of pixels of a polarization image to be acquired, for example. Is. That is, the patterning polarization / wave plate 52 alone constitutes the second polarization filter section 54 and has the same function as the second polarization filter sections 40b and 46b shown in FIGS.

  As the polarizer and phaser patterning element 53, as shown in an enlarged view in FIG. 4B, the lower left polarization angle (axis (refractive index of the refractive index) of the four polarizers of the rectangular polarizing plate 55a. Polarization angle 45 ° to the polarizer 53a of 0 °, the polarizer 53b having an upper left polarization angle of 90 °, the polarizer 53c having an upper right polarization angle of 45 °, and the polarizer having an upper right polarization angle of 90 °. A phaser-attached polarizer 53d to which the above-described phaser (wavelength plate) is attached is arranged in a 2 × 2 array to form one pixel of a polarization image.

As described above, the polarizers 53b and 53a of the polarizer and phaser patterning element 53 have longitudinal (90 °) and lateral (0 °) polarization components, and the polarizer 53c has an oblique (45 °) polarization component. Ellipsoidal polarization component (circular polarization component: 90 °, 45 °) (axis (high refractive index direction) angle: 90 °, phase difference: Δ1 = 0, axis angle: 90 °, phase difference) : Δ2 = λ / 4) can be obtained. Therefore, similarly to the second polarizing filter units 40b and 46b of the imaging units 26a and 26b shown in FIGS. Total intensity (sum of vertical and horizontal polarization vectors), vertical and horizontal (horizontal and vertical) polarization vector differences, polarization vector difference between 45 and 135 degrees, and right circular polarization Stokes para corresponding to the difference between left and right circularly polarized light It chromatography data _{S 0,} S 1, _{S 2} and can be different ones _{S 3,} also can be obtained, it can be set.

  Therefore, the polarization imaging system 12c of this embodiment also constitutes a Mueller imaging system, and can obtain at least 16 light intensity images with polarized lights having different polarization states, and all 16 polarization variables included in the Mueller matrix. Can be obtained.

  When it is not necessary to obtain all 16 polarization variables included in the Mueller matrix, the second polarization filter unit 54 of the polarization imaging system 12c shown in FIG. Instead of the patterning polarization / wave plate 52 comprising an array, a polarizer patterning element comprising an array of three polarizers having different polarization states, that is, the right side of the polarizer and phaser patterning element 53 shown in FIG. A patterning polarizing plate in which polarizer patterning elements composed of only three polarizers 53a, 53b, and 53c, which do not have a phaser-attached polarizer 53d corresponding to an elliptically polarized light component, are arranged in an array may be used. In this case, among all 16 polarization variables included in the Mueller matrix, 12 polarization variables corresponding to linearly polarized light that do not correspond to elliptically polarized light components can be obtained.

  In the case of using the patterning polarization / wave plate 52 and the patterning polarizing plate, one pixel of the CCD 56 is provided for each of the polarizers and phaser patterning elements 53 and the polarizers 53a to 53d arranged in an array of the polarizer patterning elements. Need to be detected accurately and only the polarized light from each of the polarizers 53a to 53d needs to be detected. However, it is difficult to assemble and manufacture each of the polarizers 53a to 53d and the respective pixels of the CCD 56 completely. It is preferable to perform correction processing as a signal or data.

  As described above, since the array of four polarizers of the polarizer and phaser patterning element 53 and the array of three polarizers of the polarizer patterning element become one pixel of the polarization image, the number of pixels of the CCD 56 is polarized light. Four or three times the number of pixels of the light intensity image by light is required. Therefore, if the number of pixels of the light intensity image is 200,000 pixels, for example, the number of pixels of the CCD 56 is 800,000 pixels or 600,000 pixels. If the number of pixels of the light intensity image is 1 million pixels, for example, the CCD 56 The number of pixels is 4 million pixels or 3 million pixels.

  Here, the polarization imaging system applied to the endoscope is not limited to the polarization imaging system 12c shown in FIG. 4A, but like the polarization imaging system 12d shown in FIG. In place of the first and second phase modulation elements 44a and 45a of the first polarizing filter unit 46a of the polarized light irradiation unit 24c shown in a), a first polarizing filter unit 40a using a rotational phase difference plate 38a shown in FIG. 2 is provided. The polarized light irradiation unit 24d may be used.

  Note that the polarization imaging systems 12c and 12d have a patterning polarization / wavelength plate 52 in which the polarizers and the phaser patterning elements 53 shown in FIGS. 4B and 5B are arranged in an array at the tip of the optical probe 50. Since the CCD 56 is incorporated, the polarization characteristics (polarization variable) are perfect despite the fact that the apparatus can be miniaturized, so that it can be more suitably applied to an endoscope, and is preferably incorporated into an endoscope diagnostic apparatus. be able to.

  Further, like the polarization imaging system 12e shown in FIG. 6, in the polarization imaging system 12c shown in FIG. 4A, instead of the patterning polarization / wave plate 52 and the CCD 56 arranged in the optical probe 50 of the imaging unit 26c. The reflected light in a predetermined polarization state from the digestive organ B is transmitted through the optical fiber 48 of the optical probe 50 and emitted from the other end, and the second polarizing filter unit 46b shown in FIG. The polarized reflected light emitted from the other end of the optical fiber 48 is transmitted through the image fiber 58, is incident on the second polarizing filter unit 46b, and is imaged by the CCD 56 disposed behind the polarizing filter unit 46b. The part 26d may be used.

  In this polarization imaging system 12e, since the polarized reflected light from the digestive organ B is guided by the optical fiber 48 and the image fiber 58, the resolution may be lowered, but the change in the polarization state is small and the polarization state is maintained. Therefore, since it is not necessary to incorporate the imaging unit 26d in the optical probe 50, it is not necessary to downsize the apparatus, and the degree of freedom of the apparatus configuration can be increased.

  Also in the polarization imaging system 12e of the present embodiment, the polarization characteristics (polarization variables) are perfect, as in the polarization imaging systems 12c and 12d, and can be more easily applied to the endoscope, and can be easily performed by the endoscope diagnostic apparatus. Can be incorporated.

The polarization imaging system applied to the endoscope is not limited to the polarization imaging systems 12c, 12d, and 12e, and various polarization filter units that are different or the same are used for the polarization irradiation unit 24 and the imaging unit 26. Alternatively, different or the same various phase difference providing means may be used.
The polarization imaging system 12 is basically configured as described above.

  Next, as shown in FIG. 1, the polarization conversion processing unit 14 includes image information of a plurality of light intensity images by polarized light (reflected light in a plurality of polarization states) imaged by the polarization imaging system 12, for example, 25 The light intensity image information of the frame is received from the imaging unit 26, Mueller image conversion is performed on the received plurality of light intensity image information, and a plurality of Mueller images (for example, 16 frames) with respect to a plurality of (for example, 16) polarization variables. Mueller image conversion unit 28 for obtaining (Muller image information), and a plurality of obtained Mueller images (multiple frames of Mueller image information) are subjected to polarization variable separation processing and expressed on the surface of a predetermined part of a living body A polarization variable separation processing unit 30 for converting the tissue into a polarization characteristic image (polarization characteristic image information) based on a predetermined polarization variable (polarization characteristic) for distinguishing the tissue from the surface layer; Polarizers (36a, 36b), rotational phase plates (38a, 38b), phase modulation elements (44a, 44b, 45a, 45b), patterning polarization / wave plates (52), etc. used for Mueller image conversion in the conversion unit 28 A polarizing element characteristic correction processing unit 32 that corrects polarizing element characteristics such as a polarization angle of the phase difference providing means.

  Here, the Mueller image conversion unit 28 is a part that performs a conversion process for obtaining a higher-order polarization parameter (Mueller matrix).

  By the way, when the sample M has polarization characteristics given by each element of the Mueller matrix M and the polarization characteristics represent the characteristics of the sample M, it is necessary to obtain the Mueller matrix M, that is, its elements. Here, the Mueller matrix M is a matrix of 4 rows and 4 columns and is given by the following formula (1) and has 16 elements, so that 16 Mueller images of samples by each element are obtained.

...... (1)

Here, although it is difficult to strictly correspond to each of the 16 elements m _{00 to} m ₃₃ of the Mueller matrix M and the physical properties of the polarized light, as a rough relation, the element m ₀₀ represents the luminance, 16 elements m _{00 to} m ₃₃ represent the degree of polarization, elements m ₀₁ , m ₀₂ , m ₁₀ and m ₂₀ represent dichroism (linear double absorption), and elements m ₀₃ and m ₃₀ represent Represents chromaticity (circular double absorption), elements m ₁₁ , m ₁₂ , m ₂₁ and m ₂₂ represent optical rotation (circular birefringence), and elements m _{11 to} m ₁₃ , m _{21 to} m ₂₃ and m ₃₁ to m ₃₃ is representative of the birefringence (linear birefringence).
When measuring all 16 elements m _{00 to} m ₃₃ of the Mueller matrix M, it is necessary to configure a Mueller measuring system in which the sample M is represented by the Mueller matrix as shown in FIG. Therefore, it is necessary to obtain light intensity images using light of 25 different polarization states. Note that this Mueller measurement system is composed of the same polarized light irradiation unit 24a and imaging unit 26a as the polarization imaging system 12a shown in FIG.

Here, a Mueller matrix conversion algorithm in the Mueller image conversion unit 28 will be described.
Sixteen polarization elements of the sample M are represented by the Mueller matrix M. In the Mueller measurement system shown in FIG. 7, the polarization state of the incident light on the sample M is expressed by the Stokes parameters S ₀ , S ₁ , S ₂ and represented by S _3, the polarization state of the detection light reflected from the sample M is represented by the Stokes parameter _{S '0, S' 1,} S '2 and S' _3, the Mueller matrix of the polarizing plate 36a and 36b Is P ₁ and P ₂ and the Mueller matrices of the quarter λ plates (λ / 4 wavelength plates) 38a and 38b at the angle θ are represented by R ₁ (θ) and R ₂ (5θ), the following formula (2) Satisfied.

(2)

Here, since the Stokes parameter S ′ ₀ is I (θ) (S ′ ₀ = I (θ)),
When the light intensity at the angle θ of the ¼λ plate (λ / 4 wavelength plate) 38a is Fourier transformed, it is expressed by the following formula (3).
...... (3)
Here, when the measured value of the light intensity is Φ (θ), 25 Fourier coefficients (amplitudes) a ₀ to 25 so that the error between Φ (θ) and I (θ) is minimized by the least square method. We will be seeking a ₁₂ and _b 1 _{~b 12,} since 25 pieces of the above formula for different theta (3) is needed, in the above formula (3), and the I (θ) = Φ (θ ) 25 simultaneous equations will be solved.

As a result, each element m _{00 to} m ₃₃ of the Mueller matrix M can be expressed using Fourier coefficients a _{0 to} a ₁₂ and b _{1 to} b ₁₂ as shown in the following formula (4). Each element m _{00 to} m ₃₃ of M can be obtained.
m ₀₀ = a ₀ −a ₂ + a ₈ −a ₁₀ + a ₁₂
m ₀₁ = 2 (a ₂ -a ₈ -a ₁₂ )
_{m 02 = 2 (b 2 +} b 8 -b 12)
_{m 03 = b 1 -2b 11 =} b 1 + 2b 9 = b 1 + b 9 -b 11
_{m 10 = 2 (-a 8 +} a 10 -a 12)
m ₁₁ = 4 (a ₈ + a ₁₂ )
m ₁₂ = 4 (−b ₈ + b ₁₂ )
_{m 13 = -4b 9 = 4b 11} = 2 (-b 9 + b 11)
m ₂₀ = 2 (−b ₈ + b ₁₀ −b ₁₂ )
m ₂₁ = 4 (b ₈ + b ₁₂ )
m ₂₂ = 4 (a ₈ −a ₁₂ )
_{m 23 = 4a 9 = -4a 11} = 2 (a 9 -a 11)
_{m 30 = 2b 3 -b 5 =} -b 5 + 2b 7 = b 3 -b 5 + b 7
_{m 31 = -4b 3 = -4b 7} = -2 (b 3 + b 7)
_{m 32 = -4a 3 = 4a 7} = 2 (-a 3 + a 7)
_{m 33 = -2a 4 = 2a 6} = -a 4 + a 6) ...... (4)

Note that it is difficult to make λ / 4 (90 °) strictly λ / 4 plate installed in the polarization imaging system 12a configured by the Mueller matrix polarimeter shown in FIG. 7 depending on the wavelength characteristics of the material and the manufacturing technology. Therefore, when the λ / 4 plates 38a and 38b and the polarizing plates 36a and 36b have principal axis directions and birefringence phase differences, the elements m _{00 to} m ₃₃ of the Mueller matrix include errors. Therefore, this error needs to be calibrated to improve the accuracy of polarization measurement.
These error calibration methods are omitted here, but a calibration method proposed by Chipman or Goldstein may be applied.

From the above, in order to obtain 16 Mueller images for all 16 elements of the Mueller matrix M, 25 light intensity images having different polarization states are required.
Thus, the Mueller image conversion unit 28 uses 25 light intensity images (information) with different light states obtained by imaging the angle θ every 7.2 degrees (180/25) by the conversion processing algorithm. A Mueller matrix can be obtained, and 16 Mueller images (information) based on all 16 elements can be obtained.

As can be seen from the above equation (4), some of the Fourier coefficients a _{0 to} a ₁₂ and b _{1 to} b ₁₂ are not linearly independent. Therefore, as described above, all 16 elements (Mueller parameters) of the Mueller matrix M can be obtained without using all 25 light intensity images. That is, in the present invention, when Fourier transform is performed, it is preferable to acquire 25 light intensity images, but at least 16 light intensity images may be acquired.

On the other hand, as can be seen from the above equation (1), since the Mueller matrix M has 16 elements m _{00 to} m ₃₃ , in order to obtain all of these elements (Mueller parameters), at least 16 kinds of elements are required. It can be seen that light intensity images (polarized images) having different polarization states are necessary.

Therefore, as apparent from the above equation (2), there are four types of Stokes parameters representing the polarization state of the incident light on the sample M, S ′ ₀ , S ′ ₁ , S ′ ₂ and S ′ ₃ , and Since the Stokes parameters representing the polarization state of the detection light of S are S ₀ , S ₁ , S ₂ and S ₃ , the polarization state of the incident light to the sample M and the polarization state of the detection light from the sample M are different from each other. For example, as described above, the vertical (90 °: vertical) linear polarization component, the horizontal (0 °: horizontal) linear polarization component, the oblique (45 °) linear polarization component, and the ellipticity are By setting so as to have different (90 ° / 45 °) elliptical (circular) polarization components, four Stokes parameters S ′ ₀ , S ′ ₁ , S ′ ₂ and 4 S _'3 and _{S 0, S} 1, S And for obtaining the S _3, it is possible to obtain 16 kinds of light intensity image of the sample M of the polarization state. As a result, all 16 Mueller parameters can be obtained.

  Next, the polarization variable separation processing unit 30 performs a process for separating the polarization characteristics (polarization variables) mixed in the Mueller matrix by performing a decomposition process on the Mueller matrix obtained by the Mueller image conversion unit 28. In other words, a polarization variable separation process is performed on a plurality of obtained Mueller images (multiple frames of Mueller image information), and the exposed tissue exposed on the surface layer of a predetermined part of the living body is surface layer. This is a part that is converted into a polarization characteristic image (polarization characteristic image information) based on a predetermined polarization variable (polarization characteristic) for discriminating it from the tissue. In addition, it can be said that the polarization characteristic image (polarization characteristic image information) represents the degree of expression of the exposed tissue such as collagen fibers that are exposed on the surface layer of the predetermined part.

  In the polarization variable separation processing unit 30, the Mueller matrix M is mainly divided into three types of retardance characteristics (birefringence and optical rotation), absorption characteristics (dichroism and circular dichroism), and depolarization characteristics. To be separated. From these separated polarization characteristics, the degree of depolarization, phase difference, azimuth (phase difference), azimuth (absorption) and optical rotation of a predetermined part (sample) of a living body, and further, the degree of polarization of light and the direction of polarization of light, etc. The polarization characteristics can be obtained.

  Here, the phase difference is the difference between the vertical and horizontal refractive indices of a material in a plane perpendicular to the light traveling direction, and the degree of depolarization is the degree of polarization of the light that enters the material and is emitted. This is a value indicating how much the polarization state (state indicating whether it is polarized or not (polarized)) is affected, and the direction of the phase difference indicates the direction in which the refractive index is maximum as an angle. The azimuth of absorption is the same as the dichroic azimuth, and the direction of highest absorption is expressed as an angle, and the optical rotation is the rotation characteristic with respect to linearly polarized light as an angle, and has no azimuth. This is different from the phase difference.

Meanwhile, when the Mueller matrices is M, a matrix representing the degree of depolarization and M _delta, a matrix representing the retardance (phase difference) and M _R, the matrix representing the two-color and M _D, the following formula (5 ). These matrices are 4 × 4 matrices.
_{M = M Δ M R M D} ... (5)

Thus, based on the equation (1), by degrading the Mueller matrix M, the matrix M _delta, seeking _{M R,} and _{M D,} degree of depolarization of the matrix M _delta, the phase difference from the matrix _{M R,} and matrix it can be determined dichroism from M _D.

  As for the method of decomposing the Mueller matrix and the relationship between each characteristic and the elements of the Mueller matrix, methods and relational expressions proposed by Azzam, Chipman, Goldstein, etc. Here, the detailed results are omitted, and the results are described here (“Polarized light”, Dennis Goldstein, 2th ed., Marcel Dekker, NY (2003), Chapter 9 “Mathematics of the Mueller Matrix “9.5“ The Lu-Chipman Decomposition ”P175-P186 and SPIE Vol. 3120“ Decomposition of Mueller Matrix ”P385-P396).

That is, the decomposed matrix _{M R,} given by the following equation (6) using element _m 00 _{~m 33} of the Mueller matrix M, the phase difference R is seen to be given by the following equation (7). Here, the coefficients a and b are given by the following equations (8) and (9), respectively.

The decomposed matrix M _D is also given by the following formula (10) using the elements m _{00 to} m ₃₃ of the Mueller matrix M, and the dichroism D is given by the following formula (11). Again, the coefficients a and b are given by the above equations (8) and (9), respectively.

Further, it is understood that the matrix M _Δ is given by the following formula (12) by _modifying the above formula (5), and the depolarization degree m _Δ is given by the following formula (13). Here, m ′, κ1, κ2, and κ3 are given by the above equations (14), (15), (16), (17), and (18), respectively. Incidentally, .lambda.1, .lambda.2, and λ3 can be derived from the eigenvalues of m _delta.
M _Δ = MM _D ⁻¹ M _R ⁻¹ (12)

  The present inventors have found that, among the polarization characteristics obtained in this way, there is a property of distinguishing an exposed tissue in which a specific polarization characteristic appears on the surface layer of a predetermined site from the surface layer structure.

Such polarization characteristics include phase difference, depolarization degree, azimuth (phase difference), azimuth (absorption), optical rotation, light polarization degree, light polarization azimuth, dichroism, dichroism azimuth, and p-polarized light. In addition, polarization characteristics such as s-polarized light are preferable for distinguishing an exposed structure that appears on the surface layer of a predetermined portion from a surface layer structure. As a result, polarization characteristics images based on these polarization characteristics, that is, phase difference image, depolarization degree image, orientation image (phase difference), orientation image (absorption), optical rotation image, polarization degree image of light, polarization direction of light In the image, the dichroic image, the dichroic orientation image, the p-polarized light, and the s-polarized image, the exposed tissue and the surface tissue can be distinguished and displayed, for example, in a quasi-colored manner.

  The exposed tissue that can be identified by such polarization characteristics is preferably a fibrous tissue, and the fibrous tissue is preferably collagen fibers, nerve fibers, or muscle fibers.

  Here, the polarization characteristic image will be described.

  FIG. 12 is a color image of a cross section of the normal large intestine, and FIGS. 13 and 14 are a pathologically stained specimen and a light intensity image. 15A to 15F sequentially irradiate the surface of the cross section of the normal colon shown in FIG. 12 with a plurality of polarized lights having different polarization characteristics to capture a plurality of light intensity polarization images, Depolarization degree, degree of polarization of light, phase difference, direction of phase difference, direction of absorption, polarization of optical rotation created by performing polarization conversion processing and display conversion processing on these multiple light intensity polarization images These are characteristic images (depolarization degree image, polarization degree image of light, phase difference image, azimuth image of phase difference, azimuth image of absorption, and optical rotation image), and FIG. ) Is a pseudo color palette applied to the polarization characteristic image.

  The thickness of the cross section of the normal part of the large intestine used for imaging is about 10 mm. The color image shown in FIG. 12 is captured by irradiating the surface of the cross section of the normal colon with white light (normal light) by the normal color imaging system 20 and photoelectrically converting the reflected light with a solid-state imaging device such as a CCD. FIG. 14 shows the light intensity image. In the color image and the light intensity image, it is possible to observe the state of the surface of the cross section of the normal part of the large intestine, but it is not possible to observe the inside, that is, the state from the surface layer to the middle layer and the deep layer.

  The pathologically stained specimen shown in FIG. 13 has been conventionally prepared for the purpose of pathological diagnosis. The pathologically stained specimen is prepared by slicing a cross section of a normal large intestine into a film of several microns, pasting it on a slide glass and staining it. Since this figure is a pathologically stained specimen of the cross section of the normal colon, its mucosal layer, mucosal muscle plate, submucosa, collagen fibers and the like can be observed. However, the preparation of a pathologically stained specimen is generally time consuming because it requires many man-hours and is mainly manual.

  The depolarization degree image shown in FIG. 15A has a depolarization degree in a range of 0 to 1, and for each pixel, black (depolarization degree = 0) to white (depolarization degree = 1) depending on the depolarization degree. ) Monochrome image. Similarly, in the polarization degree image of light shown in FIG. 5B, the polarization degree of light is in the range of 0 to 1, and for each pixel, black (the polarization degree of light = 1) is set in accordance with the polarization degree of light. This is a black and white image of white (degree of polarization of light = 0).

  On the other hand, the phase difference image, the phase difference azimuth image, the absorption azimuth image, and the optical rotation image shown in (C) to (F) in the same figure have each polarization characteristic angle in the range of 0 ° to 180 °, A pseudo color image is obtained by assigning different colors according to pixel angles.

  For example, in the depolarization degree image shown in FIG. 3A, the collagen fibers are portions where the depolarization degree is 0.96 to 0.98. Further, for example, in the phase difference image shown in FIG. 3C, the collagen fibers are portions where the phase difference angle is 140 ° ± 10 °.

  Next, with reference to Table 1 below, the optical characteristics, detection targets, and specific examples of the degree of depolarization, the degree of polarization of light, the phase difference, the direction of phase difference, the direction of absorption, and the polarization characteristics of optical rotation Will be explained.

  As shown in Table 1, the degree of depolarization is expressed as an optical characteristic by the degree of depolarization of an object, that is, polarization intensity × desorption (scattering). An object of detection of the degree of depolarization, that is, what can be detected by the degree of depolarization is, for example, tissue uniformity. As a specific example, it is considered that the degree of depolarization increases in a portion where adipose tissue and random fibers exist, and decreases in a portion where water and aligned fibers exist.

  In the following order, the degree of polarization of light represents the completeness of polarization of light as an optical characteristic. The detection target of the degree of polarization of light is, for example, tissue anisotropy. As a specific example, it is considered that the degree of polarization of light increases in a portion where uniform fibers exist, and decreases in a portion where water, adipose tissue, and random fibers exist.

  The phase difference represents the level of refractive index anisotropy as an optical characteristic. The detection target of the phase difference is, for example, fiber orientation. As a specific example, the phase difference is considered to increase in a portion where dense and aligned fibers exist, and to decrease in a portion where sparse fibers and random fibers exist.

  The direction of phase difference represents the direction of refractive index anisotropy as an optical characteristic. The detection target of the direction of the phase difference is, for example, the fiber orientation angle. A specific example of the phase difference azimuth is the fiber direction.

  The absorption of the phase difference represents the direction of absorption anisotropy as an optical characteristic. The detection target of the absorption of the phase difference is, for example, the orientation angle of the absorption type fiber. A specific example of phase difference absorption is the fiber absorption direction parallel to the plane of polarization of light.

  Optical rotation represents the degree of rotation of linearly polarized light as an optical characteristic. The detection target of optical rotation is, for example, a left-right inhomogeneous molecule. As a specific example, the optical rotation is considered to be large in a portion where the blood sugar or glucose concentration is high and small in a portion where water exists.

  In addition, although the example at the time of imaging the cross section of the normal large-intestine part was given and demonstrated, for example, the present invention is applied to an endoscope apparatus, and the same applies to the case where the internal surface of the normal large-intestine part is imaged. The same applies to observation sites other than the large intestine and polarization characteristics images other than those described above.

FIG. 8 is a schematic diagram of an embodiment of the polarization conversion processing unit and the polarization variable separation processing unit of the polarization image measurement and display system shown in FIG. 1, and in particular, an explanatory diagram illustrating the polarization variable separation processing unit in detail. .
As shown in FIG. 8, the polarization variable separation processing unit 30 includes a separation unit 82 that performs a decomposition process on the Mueller matrix obtained by the Mueller image conversion unit 28, and a polarization characteristic image separated by the separation unit 82. And a post-separation image forming unit 84 for forming an enhanced polarization characteristic image that has been subjected to enhancement processing for distinguishing the exposed tissue that appears on the surface layer of the region from the surface tissue, and the polarization conversion of the polarization image measurement display system 10 As described above, the processing unit 14 further performs variable separation from the Mueller image conversion unit 28 by the polarization variable separation processing unit 30 in addition to the Mueller image conversion unit 28, the polarization variable separation processing unit 30, and the polarization element characteristic correction processing unit 32. For post-separation image formation for setting the region of the polarization characteristic of the emphasized polarization characteristic image formed by the biological observation model setting unit 86 for setting the living body observation model at the time and the post-separation image forming unit 84 And a parameter setting section 88.

  The separation unit 82 uses the biological observation model set by the biological observation model setting unit 86 to separate polarization characteristics mixed in the measured Mueller matrix, that is, from each of the plurality of elements of the Mueller matrix. By performing a polarization variable separation process on a plurality of Mueller images, a predetermined polarization variable (polarization characteristic) suitable for distinguishing the exposed tissue exposed on the surface of a predetermined part of the living body from the surface tissue. This is a part for outputting a polarization characteristic image (polarization characteristic image information). For example, if the polarization characteristic is a phase difference, the output signal of the separation unit 82 is image information of 0 to 360 °.

  The post-separation image forming unit 84 identifies the exposed tissue exposed on the surface layer of a predetermined part of the living body from the surface layer tissue with respect to the polarization characteristic image based on the predetermined polarization property separated by the separation unit 82. This is a part for forming an emphasized polarization characteristic image obtained by performing enhancement processing on an emphasis region (region of interest) having a predetermined polarization characteristic set by the post-separation image forming parameter setting unit 88, and is also called an emphasized polarization property image forming unit. it can. Note that the post-separation image forming unit 84 may be provided separately from the polarization conversion processing unit 14, and the polarization characteristic image output from the polarization conversion processing unit 14 may be enhanced.

  FIGS. 9A and 9B are schematic configuration diagrams of an embodiment of a living body observation model when variables are separated by the polarization variable separation processing unit shown in FIG. 8, respectively, and polarization variable separation is performed from the Mueller image conversion unit, respectively. It is explanatory drawing explaining the biological observation model at the time of carrying out variable separation by a process part.

  As a living body observation model that can be used in the present invention, first, a “transmission model” 90a that transmits through a living body in which irradiation light in a plurality of polarization states is observed can be exemplified as shown in FIG. Here, the separation unit 82 performs variable separation by the polarization variable separation processing unit 30 on the assumption of the transmission model 90a. The transmission model 90a is a model in which a plurality of layers of “dichroism”, “phase difference × optical rotation”, and “degree of depolarization” are stacked as shown in FIG. 9A. The transmission model 90a is an effective model for acquiring the polarization characteristics of the biological sample.

  On the other hand, in an actual system, irradiation light is obliquely applied to an observed living body, and the reflected light is imaged. Therefore, it is conceivable that the “reflection model” 90b shown in FIG. 9B is used as the living body observation model as the living body observation model of the present invention. As a living body observation model in this case, for example, as shown in FIG. 9B, a plurality of “scattering (depolarization degree)”, “phase difference”, “optical rotation”, and “dichroic” layers are stacked. There are other models. Further, since the reflection model is used, reflected light is generated in each layer. For example, reflected light in which scattering + phase difference is mixed is observed. In such a reflection model, since these can be assumed, the polarization variable separation processing unit 30 can improve the variable separation accuracy, and expect to improve the accuracy of the retardance characteristic, the absorption characteristic, and the depolarization property.

  The biological observation model setting unit 86 shown in FIG. 8 is for setting the biological observation model such as the transmission model 90a and the reflection model 90b described above as the biological observation model when the variable separation is performed by the polarization variable separation processing unit. Is. In this way, by allowing the living body observation model setting unit 86 to select the living body observation model in accordance with the actual observation system, the polarization variable separation processing unit 30 increases the variable separation accuracy, the retardance characteristics, Expected to improve accuracy of absorption characteristics and depolarization.

  The post-separation image forming parameter setting unit 88 is an enhanced polarization characteristic image formed by the post-separation image forming unit 84 in order to distinguish an exposed tissue in which a specific polarization characteristic appears on the surface layer of a predetermined site from a surface layer tissue. This is intended to set the region of the polarization characteristics of each of the regions, and for each tissue to be observed, a region to be emphasized in a specific polarization property such as a phase difference can be set.

The present inventors have provided such a post-separation image forming parameter setting unit 88 in order to distinguish an exposed tissue in which a specific polarization characteristic appears on the surface layer of a predetermined site from the surface layer tissue. This is because it has been found that it is necessary to be able to set a phase difference region to be enhanced if the polarization property region to be enhanced, for example, if the polarization property is a phase difference, for each observation tissue.
In the present invention, at the time of observing the polarization characteristic image, by selecting an appropriate parameter for each observed tissue from the post-separation image forming parameter setting unit 88, the exposed tissue exposed on the surface layer is clearly distinguished from the surface tissue. can do.

  For example, if the polarization characteristic is a phase difference, the output signal from the separation unit 82 is image information of 0 to 360 °. Therefore, when the observation tissue is collagen fibers, the phase difference region to be emphasized is separated. The post-image forming parameter setting unit 88 can set an area of 140 ° ± 10 °.

  In addition, although the example of setting the area | region of the polarization characteristic which should be emphasized here for every observation tissue (a nerve, a lymph node, a blood vessel) was shown, each observation part (upper digestive organ, lower digestive organ, respiratory organs) was shown. You may make it set.

In particular, the degree of expression of collagen fibers is effective in diagnosing the degree of progression of cancer.
The relationship between the degree of progression of cancer and the degree of expression of collagen fibers can be considered as follows.

FIG. 10A is a schematic configuration schematic diagram in the vicinity of the surface layer of a normal living body, and FIG. 10B is a schematic configuration schematic diagram in the vicinity of the surface layer of the living body in which intramucosal cancer has occurred. c) is a schematic structural schematic diagram of the vicinity of the surface layer of a living body that has progressed to submucosal invasive cancer.
As shown in FIG. 10 (a), a tissue 60a near the surface layer of a normal living body has a mucosal layer 62 from the surface side, a mucosal muscle plate 64 below it, and a submucosal layer 66 below it. It exists in the submucosal layer 66 below the mucosal muscle plate 64.

  Next, in the tissue 60b in the vicinity of the surface layer of the living body in which the intramucosal cancer has occurred as shown in FIG. 10B, the intramucosal cancer (m cancer) 70 has occurred in the mucosal layer 62. The lower mucosal muscle plate 64 is not torn, and the collagen fibers 68 present in the lower mucosal layer 66 below the mucosal muscle plate 64 are not exposed to the mucosal layer 62. For this reason, in the tissue 60b near the surface of the living body in which intramucosal cancer has occurred, even if the polarization measurement according to the present invention is performed, the tissue 60b appears in the mucosal layer 62 as in the case of the tissue 60a near the surface of a normal living body. It is not possible to detect the collagen fibers 68.

  In contrast, in the tissue 60c in the vicinity of the surface layer of the living body where the cancer 72 shown in FIG. 10C has progressed, that is, the submucosal invasive cancer (sm cancer) 72 exists, the submucosal invasive cancer 72 is present. The mucosal muscle plate 64 of the portion that has progressed to the right is torn, the collagen fibers 68 of the submucosa 66 move from the torn portion 65 to the mucosa layer 62, and grow between the cancer cells 72 of the surface mucosa layer 62 The collagen fibers 68 are exposed to the surface mucosa layer 62. For this reason, in the tissue 60c in the vicinity of the surface layer of the living body where the submucosal invasive cancer 72 exists, the polarization measurement according to the present invention can be performed to detect the collagen fibers 68 exposed in the mucosal layer 62, and other tissues. Can be identified. As a result, the collagen fibers 68 appearing on the mucosal layer 62 can be colored, the expression of the collagen fibers 68 to the mucosal layer 62 can be known, and the submucosal invasive cancer 72 can be detected. .

  That is, as shown in FIG. 10 (c), when the mucosal muscle plate 64 is broken as the submucosal invasive cancer 72 progresses, fibroblasts generate collagen fibers 68 from the submucosal layer 66 below the mucosal muscle plate 64. The cells enter, and the collagen fibers 68 in the submucosal layer 66 move to the mucosal layer 62 from the tearing, and many collagen fibers 68 are generated in the upper mucosal layer 62. That is, it is possible to distinguish between the intramucosal cancer 70 shown in FIG. 10B and the submucosal invasive cancer 72 shown in FIG.

Since the collagen fibers 68 are made of a polymer and have optical anisotropy, the collagen fibers 68 can be distinguished from the mucosal layer 62 by the polarization characteristics, and can be displayed in an identifiable manner. Therefore, the collagen fibers 68 can be visualized as a pseudo color image so as to be distinguishable from the mucosal layer 62.
Therefore, if such an image shows that collagen fibers have grown between cancer cells on the surface of a given site and the interstitial change (the expression of collagen fibers to the mucosa) can be confirmed, it is diagnosed that metastasis is highly likely. It is possible to diagnose whether it is cancer or not, and whether it is intramucosal cancer or submucosal invasive cancer.

  Here, the enhancement process of the polarization characteristic image in the post-separation image forming unit 84 will be described.

  The post-separation image formation parameter setting unit 88 is a parameter for designating an emphasis region (region of interest) to be highlighted in the polarization characteristic image corresponding to the polarization characteristic image information obtained by the deflection conversion processing unit, that is, after separation. A parameter setting table that performs enhancement processing on the polarization characteristic image in the image forming unit 84 and stores parameters for designating an enhancement region for forming the enhanced polarization characteristic image for each observation site and for each polarization characteristic image Have

  FIG. 16 is an example of a parameter setting table. The figure illustrates a parameter setting table for adult boys and a parameter setting table for adult girls. For example, in the vertical direction of the parameter setting table for adult males, the upper digestive organs, the lower digestive organs,... Are shown as observation locations (parts), and in the horizontal direction, phase difference (collagenous fibers) as polarization characteristics images. ), Depolarization degree (collagen fiber),... (Collagenous fiber) represents that the collagenous fiber is set as the emphasis region.

  In the parameter setting table shown in the figure, for example, at the intersection of the upper digestive organ and the phase difference (collagenous fiber), the phase difference angle is in the range of 0 ° to 180 °, and the phase difference angle of the collagenous fiber is 140. It is shown to be ± 10 °. The intersection of the upper digestive organ and the degree of depolarization (collagen fiber) indicates that the degree of depolarization of the collagen fiber is 0.96 to 0.98, with the degree of depolarization being in the range of 0 to 1. ing. Data in the parameter setting table is set in advance.

  In addition, although description of a specific numerical value is abbreviate | omitted about the lower digestive organ, it is the same as that of the upper digestive organ. The parameter setting table for adult girls is the same as the parameter setting table for adult boys.

  Here, for example, the upper digestive unit is designated as the observation part and the phase difference is designated as the polarization characteristic image by the observation part designation information and the polarization characteristic image designation information input from the outside via an input device (not shown). In this case, the phase difference angle 140 ° ± 10 ° at the intersection of the two is output as a parameter and input to the post-separation image forming unit 84.

  When the post-separation image forming unit 84 receives a phase difference angle of 140 ° ± 10 ° from the post-separation image forming parameter setting unit 88 as a parameter, the post-separation image forming unit 84 applies the phase difference polarization characteristic image separated by the separation unit 82. Then, a predetermined enhancement process is performed on an area (enhancement area) corresponding to a parameter phase difference angle of 140 ° ± 10 ° to form an enhanced polarization characteristic image. As a result, the collagen fiber region is highlighted in the enhanced polarization characteristic image.

The emphasis processing in the post-separation image forming unit 84 may be any emphasis method as long as the emphasis area corresponding to the parameter can be emphasized and displayed. For example, the following (1) to (5) are performed. It can be illustrated.
(1) An enhancement process is performed to expand the dynamic range of the enhancement region and compress the dynamic range of other regions.
(2) An area other than the emphasized area is removed, and an emphasis process is performed to display only the emphasized area in a pseudo color display.
(3) Emphasis processing is performed so that only the emphasis area is displayed in pseudo color and the other areas are displayed in black and white.
(4) An emphasis process is performed in which an area including the emphasis area is outlined in black and white.
(5) Emphasis processing is performed to enclose an area including the emphasis area with a line.

  For example, in the case of the enhancement method (1), assuming that the pseudo color of the 140 ° ± 10 ° portion which is the angle of the phase difference of the collagen fibers in the phase difference image is displayed with one color, the dynamic range is expanded. The pseudo-color palette different from the pseudo-color palette used for pseudo-color display of the part other than the highlight region is used to display the 140 ° ± 10 ° part in pseudo-color with a plurality of colors. That is, when the dynamic range is expanded, the emphasized area is displayed with a finer resolution than before the expansion.

  The enhancement method may be specified, for example, as a parameter in a parameter setting table, or may be input from the outside in the same manner as the monitoring region and the polarization characteristic image. Moreover, it is not essential to use the parameter setting table as in the present embodiment. Without providing the parameter setting table, for example, the fact that the phase difference angle is 140 ° ± 10 ° may be directly input from the outside via the input device as a parameter for emphasizing the phase difference image.

  In the parameter setting table, the observation location (part) is an indispensable item, but the polarization characteristic image is not an indispensable item. For example, the polarization characteristic image subjected to the enhancement process may be only the phase difference (collagen fiber). In this case, since the polarization characteristic image is only the phase difference (collagen fiber), it is not necessary to designate the polarization characteristic image. Further, the parameter setting table is not limited to the parameter setting table for adult boys and adult girls, but may be appropriately provided according to the type of subject such as for elementary school students, junior high school students, and high school students.

  Next, the display conversion processing unit 16 performs display conversion processing, that is, display color brightness image conversion processing, on the polarization characteristic image (information) having a predetermined polarization characteristic obtained by the polarization variable separation processing unit 30 of the polarization conversion processing unit 14. And performing the polarization characteristic image (information) visualization so that the exposed tissue can be discriminated from the surface tissue, and for example, colored into a pseudo color and converted into display polarization characteristic image information for pseudo color display It is. When the post-separation image forming unit 84 of the polarization variable separation processing unit 30 performs the enhancement process on the polarization characteristic image and obtains the enhanced polarization characteristic image information, the display conversion processing unit 16 displays the enhanced polarization characteristic image. The information is converted into display enhanced polarization characteristic image information for visualization and display. For example, when emphasis processing is performed on the phase difference image information and the emphasis phase difference image information is obtained, the display conversion processing unit 16 displays the emphasis phase difference image information for visualization. Conversion to enhanced phase difference image information. The same applies to other emphasized polarization characteristic image information.

  Here, the display conversion processing by the display conversion processing unit 16 is based on the polarization characteristic image information, and the colors to be colored on the exposed tissue and the surface tissue according to the value of the predetermined polarization variable (intensity of the polarization characteristic). It is preferable to generate and display polarization characteristic image information for visualizing and displaying the expression distribution of the exposed tissue by determining and color-mapping the exposed tissue and the color to be colored on the surface tissue. .

The display unit 18 is configured to visualize the display tissue on the display screen based on the display polarization characteristic image information obtained by the display conversion processing unit 16 so as to be distinguishable from the surface layer tissue, that is, to perform pseudo color display. When the display conversion processing unit 16 obtains the display enhanced polarization characteristic image information, the display unit 18 uses the display enhanced polarization characteristic image information to display the display enhanced polarization characteristic corresponding to the display enhanced polarization characteristic image information. Display the characteristic image. For example, when the display enhanced phase difference image information is obtained by the display conversion processing unit 16, the display unit 18 performs display corresponding to the enhanced phase difference image information for display based on the enhanced phase difference image information for display. Displays an enhanced phase difference image. The same applies to other display enhanced polarization characteristics images. A known monitor or display can be used for the display unit 18.
Note that the display of the polarization characteristic image by the display unit 18 preferably displays the distribution of the exposed tissue colored to the color to be colored based on the display polarization characteristic image information.

  The normal color imaging system 20 obtains a light intensity image (information) obtained by irradiating a predetermined site with illumination light for normal observation and imaging the reflected light. An image capturing system can be used.

  In addition, the image composition unit 22 generates a display polarization characteristic image and a display polarization characteristic image based on the display polarization characteristic image information obtained by the display conversion processing unit 16 and the normal color light intensity image information obtained by the normal color imaging system 20. In combination with a normal color light intensity image, for example, the combined image information for display is generated by superimposing or arranging them together, or processing both. Further, the image composition unit 22 uses a plurality of display polarization characteristic image information obtained by the display conversion processing unit 16 and having a plurality of display polarization characteristic image information having different polarization characteristics, and a plurality of display polarization characteristics respectively corresponding to the plurality of display polarization characteristic image information. The composite image information is created by combining two or more display polarization characteristic images among the characteristic images. As a result, the display unit 18 can display a composite image based on the composite image information.

  Here, a display method of the polarization characteristic image in the image composition unit 22 will be described.

  The image composition unit 22 is based on the display polarization characteristic image information obtained by the display conversion processing unit 16 by, for example, an external input via an input device or according to preset combination conditions. Depolarization degree image, light polarization degree image, phase difference image, phase difference azimuth image, absorption azimuth image, optical rotation image (that is, display polarization characteristic image information Displaying a combination of two or more display polarization characteristic images among a plurality of corresponding display polarization characteristic images), for example, displaying two or more polarization characteristic images superimposed, side by side, or arithmetically processed. Is generated. As a result, a composite image based on the composite image information is displayed on the display unit 18.

  As a combination of two or more polarization characteristic images, for example, a combination of a depolarization degree image and a phase difference image, a combination of a depolarization degree image, a phase difference image, and a azimuth image of a phase difference, a depolarization degree image, and a phase difference image Examples include combinations of optical rotation images, depolarization degree images, phase difference images, phase difference azimuth images, and optical rotation images, and the like. Moreover, you may use the polarization degree image of light instead of a depolarization degree image. Further, an absorption azimuth image may be used instead of or in addition to the phase difference azimuth image.

  Taking the degree of depolarization as an example, it is considered that the degree of depolarization increases because the scattering property is large in a portion where adipose tissue or random fibers are present. On the other hand, since polarized light passes through water without being depolarized, it is considered that the degree of depolarization becomes small in the portion where water exists. In addition, since aligned fibers have directionality and anisotropy increase, it is considered that the degree of depolarization decreases in a portion where aligned fibers exist.

  For example, collagen fibers are present in the normal region in a state aligned with the submucosa region. Therefore, in this state, the degree of depolarization becomes small. On the other hand, in the lesioned part, collagen fibers break the upper mucosal muscle plate below the submucosa and further appear on the upper mucosal layer. Since the collagen fibers exposed to the mucosal layer are random fibers, the degree of depolarization is increased in the portion of the mucosal layer where the collagen fibers are present, that is, the lesioned part.

  Therefore, by displaying the depolarization degree image on the display device, the doctor sees the depolarization degree image, confirms the portion where the depolarization degree is large, and diagnoses that this portion may be a lesioned part. Can help to do.

  As for the degree of polarization and the phase difference of light, the angle of the degree of polarization of the light and the phase difference are small in a portion where random fibers are present. That is, the degree of polarization of light and the angle of phase difference in the lesioned part are reduced. Therefore, by displaying the light polarization degree image and phase difference image on the display device, the doctor sees the light polarization degree image and phase difference image and confirms the part where the light polarization degree and phase difference angle are small. In addition, it is possible to provide support for making a diagnosis that this portion may be a lesion.

  The direction of the fibers and the direction of absorption of the fibers can be confirmed by looking at the azimuth image of the phase difference and the absorption azimuth image, but the angle of the phase difference cannot be determined by looking only at these polarization characteristics images. . Accordingly, it is desirable to view the phase difference azimuth image and the phase difference absorption image in combination with the phase difference image. Thereby, the angle of the phase difference can be seen together with the fiber direction and the fiber absorption direction.

  In addition, blood glucose and glucose concentrations can be detected by optical rotation. That is, as the blood glucose or glucose concentration increases, the angle of optical rotation increases. For example, when cancer develops, blood vessels are created to supply nutrients to the cancer, and a lot of nutrients are supplied. As a result, the amount of glucose that supplies nutrients also increases. Therefore, by displaying the optical rotation image on the display device, the doctor sees the optical rotation image, confirms the portion where the amount of glucose is increasing, and diagnoses that this portion may have cancer Can provide support.

  As described above, the collagen fibers are fibers and thus have a direction. Only by observing the phase difference image, only the anisotropy angle (intensity), that is, the anisotropy of the refractive index is observed. On the other hand, by observing the orientation image of the phase difference, the orientation of the collagen fibers, that is, the direction in which the refractive index is high can be found. Although the direction of collagen fibers is uniform in the submucosa, for example, when it is in the vertical direction, it can be diagnosed that there is a possibility of a lesion.

  In this way, by combining and displaying two or more polarization characteristic images, it is not necessary to sequentially replace and display the two or more polarization characteristic images, and the two or more polarization characteristic images can be observed while being compared. Thereby, even if it is difficult to diagnose with only one polarization characteristic image, a doctor can diagnose a lesion by looking at two or more polarization characteristic images. Accuracy can be improved.

  Further, based on the display polarization characteristic image information obtained by the display conversion processing unit 16 and the normal color light intensity image information obtained by the normal color imaging system 20, two or more polarization characteristic images and the normal color light intensity are obtained. An image or a light intensity image may be displayed in combination.

  The polarized image measurement display system of the present invention is basically configured as described above.

Below, the action of the polarization image measurement display system of the present invention, and the polarization image measurement method and polarization image display method implemented in these will be described.
FIG. 11 is a flowchart showing an example of a polarization image display method according to the polarization image measurement method implemented in the polarization image measurement and display system of the present invention, that is, a polarization image measurement and display method.

  First, in the present invention, in step S100, the polarization image measurement display system 10 shown in FIG. 1 is prepared to measure the surface layer of a predetermined part of the living body, and the number of light intensity images in different polarization states to be captured, Various initial values and conditions used in the polarization image measurement display system 10 are set.

  Next, in step S102, the polarized light irradiation unit 24 of the polarization imaging system 12 of the polarization image measurement display system 10 irradiates a predetermined part of the living body with irradiation light in a predetermined polarization state from its surface layer.

  Subsequently, in step S104, reflected light of a predetermined polarization state from the surface layer of a predetermined portion by irradiation light of a predetermined polarization state irradiated by the polarization irradiation unit 24 is imaged by the imaging unit 26, and one polarization modulation is performed. The light intensity image (data) of the surface layer of the predetermined part of the living body is measured and acquired.

  Next, in step S106, it is determined whether the obtained light intensity image (data) has reached a predetermined number, preferably at least 16, for example, 25, and if it has not reached the predetermined number ( NO), returning to step S102, the polarized light irradiation unit 24 changes the polarization state and changes the irradiation light irradiation step S102 for irradiating a predetermined part of the living body and the next step S104 according to the polarization state of the irradiation light. The imaging step S104 in which the reflected light in the polarized state is imaged by the imaging unit 26 to acquire one light intensity image (data) is repeated until the predetermined number is reached. The process moves to step S108.

  Next, in step S108, the polarization conversion processing unit 14 performs polarization conversion processing on at least 16 light intensity images (data) acquired by the imaging unit 26. That is, in sub-step S110, the polarization conversion processing unit 14 16 Mueller images (data) are obtained by the Mueller image conversion process of the Mueller image conversion unit 28, and further, in the sub-step S112, the exposed tissue that is displayed on the surface layer of the predetermined part by the polarization variable separation processing unit 30 Is a polarization variable (data) with clear physical meaning (phase difference, phase difference azimuth, depolarization degree, polarization degree of light, dichroism, dichroic azimuth, optical rotation, A polarization characteristic image (data) based on a predetermined polarization variable (polarization characteristic) is acquired by separating and converting into light polarization direction and P / S polarization.

  Subsequently, in step S114, the display tissue of the polarization characteristic image (data) obtained by the polarization conversion processing unit 14 can be distinguished from the surface tissue by the display conversion processing unit 16. In order to visualize and display, the image is converted into a display image (data) colored in a pseudo color.

  In step S108, after obtaining the polarization characteristic image (data) by the polarization variable separation processing unit 30, the post-separation image forming unit 84 performs enhancement processing on the region of interest in the polarization characteristic image, and enhances it. A processed polarization characteristic image (data) is formed, and in step S114, the display conversion processing unit 16 performs display conversion processing on the enhanced polarization characteristic image (data) formed by the post-separation image forming unit 84. It may be converted into a display image (data) colored in a pseudo color.

  In step S114, the display conversion processing unit 16 obtains the display image (data), and then the image composition unit 22 captures the image in advance based on the display image (data) obtained by the display conversion processing unit 16. Display of a combination of two or more of the depolarization degree image, the polarization degree image of the light, the phase difference image, the phase difference azimuth image, the absorption azimuth image, and the optical rotation image, for example, two or more It is also possible to generate composite image information for displaying the polarization characteristic images superimposed or side by side, and display the composite image based on the composite image information (data) on the display unit 18.

Next, in step S116, based on the display image (data) obtained by the display conversion processing unit 16, the exposed tissue that appears on the surface layer of the predetermined part is visualized and displayed so as to be distinguishable from the surface tissue. Therefore, a display image colored in a pseudo color as a display color that can be easily determined by a doctor is displayed on the monitor screen of the display unit 18.
Thus, the polarization image display method according to the present invention is completed.

  The present inventors use the polarized image measurement display system 10 to perform the polarization image display method described above, measure the surface of the cancerous part of the stomach with the polarization imaging system 12, and display the display unit 18. As shown on the monitor screen, it was confirmed on the monitor screen that there was a clear difference that was not seen in the normal part of the stomach.

  In the polarized image display method according to the present invention, in another step, the normal color imaging system 20 irradiates a predetermined part with illumination light for normal observation and images the reflected light to obtain normal color light intensity image information ( In the next step, the image combining unit 22 obtains the display polarization characteristic image information (data) obtained by the display conversion processing unit 16 and the normal color obtained by the normal color imaging system 20 in the next step. Based on the light intensity image information (data), composite image information (data) for displaying the polarization characteristic image for display and the normal color light intensity image on top of each other or displaying them side by side is generated and displayed in the next step. The unit 18 may display a composite image based on the composite image information (data).

In the present invention, the polarization imaging system (light source, polarization camera) 12 shown in FIG. 1 measures four polarization-modulated light intensity images of a living body, converts them into phase difference images and phase difference azimuth images, and provides a doctor. Can be displayed on the monitor screen of the display unit 18 as a display color that can be easily determined.
When the surface of the cancerous part of the stomach was measured with this optical system, it was confirmed that there was a clear phase difference that was not found in the normal part of the stomach.

  Furthermore, in the present invention, the polarization imaging system 12 of the polarization image measurement and display system 10 shown in FIG. 1 measures the light intensity images of the surface layer of a predetermined part of the living body subjected to polarization modulation of four and three, and in each case The polarization conversion processing unit 14 performs polarization conversion processing, converts it into a phase difference image and a phase difference azimuth image, converts it into display image information colored in a pseudo color in the display conversion processing unit 16, and the doctor determines It is displayed on the monitor screen of the display unit 18 as an easy display color.

  In addition, when the present inventors measured the surface of the cancerous part of the stomach with the polarization imaging system 12 using this optical image measurement display system 10, in the case of four light intensity images, In the case of the light intensity image, it was confirmed on the monitor screen that there was a clear difference that was not seen in the normal part of the stomach.

The present invention is basically as described above.
Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and it is needless to say that various improvements and modifications may be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Polarization image measurement display system 12, 12a, 12b, 12c, 12d, 12e Polarization imaging system 14 Polarization conversion process part 16 Display conversion process part 18 Display part 20 Normal color imaging system 22 Image composition part 24, 24a, 24b, 24c Polarization Irradiation unit 26, 26a, 26b, 26c, 26d Imaging unit 28 Mueller image conversion unit 30 Polarization variable separation processing unit 32 Polarization element characteristic correction processing unit 34 Light source 36a, 36b Polarizing plate 38a, 38b Rotating phase difference plate 40a, 40b, 46a , 46b, 54 Polarization filter section 42 Camera 44a, 44b, 45a, 45b Phase modulation element 48 Optical fiber 50 Optical probe 52 Patterning polarization / wave plate 53 Polarizer and phaser patterning element 56 CCD
82 Separating unit 84 Image forming unit after separation 86 Biological observation model setting unit 88 Image forming parameter setting unit after separation

Claims (6)

An irradiation unit that sequentially irradiates a subject with a plurality of polarized lights having different polarization states;
An imaging unit that sequentially images reflected light from the subject each time the polarized light having a different polarization state is irradiated from the irradiation unit to the subject, and outputs the light intensity image information;
Polarization conversion processing is performed on a plurality of light intensity image information of reflected light from a subject of a plurality of polarized lights having different polarization states output from the imaging unit, and converted into phase difference image information based on polarization characteristics of a phase difference. A polarization conversion processing unit to convert;
Emphasized polarization characteristics to obtain enhanced phase difference image information by performing enhancement processing for emphasizing a region of a predetermined phase difference angle inputted from the outside with respect to the phase difference image information obtained by the deflection conversion processing unit An image forming unit;
A display conversion processing unit that converts the enhanced phase difference image information obtained by the enhanced polarization characteristic image forming unit into display enhanced phase difference image information for visualization and display;
A display unit that displays a display enhanced phase difference image corresponding to the display enhanced phase difference image information based on the display enhanced phase difference image information obtained by the display conversion processing unit. Polarized image measurement display system.   2. The enhancement polarization characteristic image forming unit performs enhancement processing for expanding a dynamic range of the region having the predetermined phase difference angle and compressing a dynamic range of the other angle region. Polarized image measurement display system.   The enhancement polarization characteristic image forming unit removes an area other than the predetermined phase difference angle area and performs an enhancement process for displaying only the predetermined phase difference angle area in a pseudo color display. 1. A polarization image measurement display system according to 1.   2. The enhancement polarization characteristic image forming unit is configured to perform enhancement processing for displaying only the region having the predetermined phase difference angle in pseudo color and displaying the other angle region in black and white. Polarized image measurement display system.   The polarized image measurement display system according to claim 1, wherein the emphasized polarization characteristic image forming unit performs an enhancement process in which a region including the region having the predetermined phase difference angle is outlined in black and white.   The polarization image measurement display system according to claim 1, wherein the enhancement polarization characteristic image forming unit performs enhancement processing in which a region including the region having the predetermined phase difference angle is surrounded by a line.