Observation device, observation method, cassette, and plate

Abstract

There has been a demand for clearer observation of the behavior of a catheter, especially the movement of a wire or the like in a sheath of the catheter, without using an X-ray when performing technical training for endovascular surgery and the evaluation thereof.　If there is a difference between the light quantity of a polarization component imaged by a light reception unit in light derived from a sheath and the light quantity of the polarization component imaged by the light reception unit in light derived from a member around the sheath, the sheath can be displayed so as to be identifiable on an image. Since the light reception unit receives the polarization component, light reflected or scattered at the interface of a member constituting an object to be observed is substantially eliminated and thus the image becomes clear.

Description

Observation device, observation method, cassette and plate

[0001] The present invention relates to an observation device and method for observing a catheter inserted into a blood vessel model.

[0002] In the evaluation of catheters to be inserted into blood vessels, and in technical training and evaluation of endovascular surgery, it is necessary to observe the state of a vascular model and the catheter inserted into the vascular model. Evaluation of technical training in endovascular surgery has traditionally been performed by taking X-rays with the catheter inserted into the vascular model. From the standpoint of avoiding X-ray exposure for trainers and trainees, the present applicant has proposed an observation device using near-infrared rays (see Patent Document 1).

[0003] International Patent Publication WO / 2024 / 014496

[0004] The observation device proposed in Patent Document 1 makes it possible to observe the behavior of a catheter inserted into a vascular model without using any X-rays, but trainers who provide technical training and evaluations for endovascular surgery have requested a way to more clearly observe the behavior of the catheter, particularly the movement of the wire inside the catheter sheath.

[0005] The present inventors conducted extensive research to solve the above-mentioned problems and came up with the idea of ​​using polarized light. As described in prior art documents, near-infrared light can pass through a blood vessel model or a catheter sheath. When an object to be observed is placed between a first polarizing plate and a second polarizing plate whose polarization axes are orthogonal to each other, and the object is irradiated with near-infrared light from the first polarizing plate side for transmission observation of the object, it is not possible to observe an image of the blood vessel model or the catheter sheath. This is because even if near-infrared light polarized in a first direction by the first polarizing plate passes directly through the blood vessel model or the catheter sheath, it is blocked by the second polarizing plate.

[0006] However, if the catheter sheath is made of a material that scatters polarized near-infrared light, the scattering can modulate the polarization direction and generate polarized components that can pass through the second polarizer. A metal linear object, such as a wire, inserted into the sheath does not transmit any irradiated light and appears as a shadow on the image. That is, the sheath portion, where the polarized near-infrared light is scattered, appears bright on the screen, providing a high brightness contrast with the shadowed wire portion. Furthermore, if the sheath is placed in air or fresh water, for example, the polarization state is maintained in the area surrounding the sheath, and the irradiated light that passes through this area is also blocked by the second polarizer, resulting in a dark appearance of this area. As a result, a high dark-light-dark contrast is achieved between the wire portion, the sheath portion, and the area surrounding the sheath.

[0007] The observation device proposed in Patent Document 1 allows near-infrared light to penetrate the object of observation in the same way as X-rays, thereby producing a flat image similar to an X-ray image with reduced three-dimensionality. However, when diffuse reflection of the irradiated light occurs at the interfaces of the vascular model and its surrounding components, the amount of diffusely reflected light becomes greater than the amount of light transmitted through each component, causing the diffused light to blur the interface lines. Therefore, the image of each component based on the transmitted light on the display is interfered with by the diffusely reflected light, contributing to blurring the images of the components that are the intended target of observation. Therefore, there has been a demand for a clearer observation of catheter behavior, particularly the movement of wires within the catheter sheath, when conducting technical training for endovascular surgery or catheter evaluation.

[0008] The inventors conducted extensive research to solve the above-mentioned problems and discovered that this problem could be solved by utilizing polarized light. By selectively receiving the polarized light component originating from the component that is the object of observation, it was possible to substantially eliminate the diffused light reflected from the component's interface. As a result, when all of the received light, including the diffused light, was filtered using a polarizing plate, a clearer image could be obtained. Near-infrared light scattered at the interfaces of the blood vessel model and its surrounding components can be modulated, generating polarized components according to certain rules. However, even among the polarized components generated in this way, only a small portion can pass through the polarizing plate on the light-receiving side, and it is believed that they contribute very little to image formation.

[0009] The present invention was made based on this finding, and one aspect thereof is defined as follows: That is, an observation device for observing a blood vessel model into which a catheter is inserted, comprising: an observation assembly including a light-emitting unit and a light-receiving unit; and an image display assembly including an image generating unit and a display, wherein the light-emitting unit has a light source and a polarizing element and irradiates reference illumination light including a first polarized light toward the observation object, the polarizing element has a polarization axis in a first direction and transmits the first polarized light polarized in the first direction out of the light output from the light source, and the first polarized light passes through a sheath of the catheter, and the polarization state of at least some of the light components is modulated, the light-receiving unit has a light receiver and an analyzer, the analyzer has a polarization axis in a direction different from the first direction, and the light receiver receives a polarized component that has passed through the analyzer out of the reference illumination light (post-illumination light) that has been irradiated to the observation object and has undergone interference from the observation object, and generates an observation output, the image generating unit receives the observation output and generates an image, and the display displays the image.

[0010] According to the observation device defined in this manner, when the first polarized light contained in the reference illumination light passes through the catheter sheath, the polarization state of at least some of the polarized light components is modulated due to interference, such as scattering, from the sheath's constituent material. For example, if the polarizing element is a polarizing plate that generates linearly polarized light and the analyzer is a polarizing plate with a polarization axis oriented perpendicular to the polarizing plate, the first polarized light that passes through the observation target as is cannot pass through the analyzer, which has a different polarization axis. However, some of the polarized light components whose polarization direction is modulated by the sheath can pass through the analyzer. The transmitted polarized light components are received by the photodetector, and an observation output corresponding to the amount of received light is generated. Note that in this specification, "polarization direction" includes the meaning of the "vector direction" of the Jones vector (Jones parameter) and the "vector direction" of the Stokes vector (Stokes parameter), which are used to mathematically express polarization states in general.

[0011] In the image generated by the image generator based on the observation output, the metal linear object (hereinafter sometimes abbreviated as "wire" in this specification) and the sheath are displayed with a contrast in brightness. Specifically, the wire portion, which does not transmit any light, is displayed in black, while the sheath portion, which receives the polarized light component that has been modulated and passed through the analyzer, is displayed in relatively white.

[0012] Polarizing and / or reflective materials are contained within or at the interface of the outer circumferential material of the catheter (e.g., circulating fluid, vascular model, immersion fluid) and the inner circumferential material of the catheter (e.g., liquid for continuous flushing). These materials interfere with all or part of the reference illumination light containing the first polarized light, modulating its polarization state. Some of the polarized components modulated in this manner pass through the analyzer. If the amount of the polarized components passing through differs from that originating from the sheath, the inner and outer circumferential portions of the catheter will appear on the image with a brightness different from that of the sheath and wire. Examples of polarizing materials include diffractive materials, liquid crystals, and birefringent materials.

[0013] The so-called secondary light, which is generated by the diffuse reflection of the reference illumination light at the interfaces between the catheter and its inner and outer components, is filtered by the analyzer, so that although some of the polarized components can pass through, they do not substantially affect the image. This allows for a clear observation image to be obtained. By making the light transmittance of the inner and outer peripheral components of the catheter different from that of the sheath, a brightness difference can also be created between them in the image.

[0014] The inventors have confirmed that the above observation device can clearly distinguish and display the catheter sheath and wire on an image without using X-rays (see Examples). The basic configuration of the observation device is as follows: The light irradiated onto the observation object is polarized (first polarization), and an image is generated based on the polarization component that can transmit through the analyzer among the polarization components modulated when this first polarization is irradiated onto the observation object. The inventors have thoroughly studied the principle behind why the above configuration using polarized light enables the sheath to be more clearly identified compared to a configuration (conventional configuration) that does not use any polarization. As a result, they have noticed the following.

[0015] (1) Basic Principle for Identifying Sheaths If there is a difference between the amount of polarized light components imaged by the light-receiving unit in the light originating from the sheath and the amount of polarized light components imaged by the light-receiving unit in the light originating from the components surrounding the sheath, the sheath can be displayed in an identifiable manner on the image. The light that can be imaged by the light-receiving unit depends on the correlation between the polarization characteristics of the light and the polarization characteristics (directionality, such as linear polarization or circular polarization) of the light-receiving unit. Therefore, the polarized component of the light originating from the sheath that matches the polarization characteristics of the light-receiving unit serves as the source of image generation in the light-receiving unit. If the light originating from the sheath and the light originating from other components (referred to as "reference illumination light" in this specification) are the same, the material of the sheath differs from the material of the other components, resulting in differences in the polarized components imaged by the light-receiving unit in the light originating from each component. This results in differences in brightness on the image, which represent each component. Here, the reference illumination light irradiated onto the object of observation can be polarized as a whole, or it can contain a polarized component in part. Non-polarized light can also be used as the reference illumination light. This is because polarized light components can be generated by the reflection of unpolarized light from an object being observed.

[0016] (2) Polarized Components Imaged by the Light-Receiving Unit In this specification, "imaged by the light-receiving unit" means that the light-receiving unit provides an output for generating an image. The following are examples of imaging when the light-receiving unit receives polarized components with predetermined polarization characteristics. (2-1) When the wavelength of the polarized components is visible light, an analyzer that allows the polarized components to pass through is used as the light-receiving unit. The polarized components that pass through the analyzer are visible as output, allowing the observer to recognize the output image. (2-2) When the wavelength of the polarized components is near-infrared light, the light-receiving unit includes an analyzer and a light-receiver. The analyzer allows the polarized components to pass through. The light-receiver receives the polarized components that have passed through and outputs a corresponding observation output. This observation output becomes the output for generating an image and is sent to the image generation unit where it is imaged. (2-3) The combination of a polarizer and a light-receiver can also be applied to polarized components of visible light. (2-4) If the element directly converts polarized light into an electrical signal (photoelectric conversion element), the element can be used as a light receiving unit. In this case, the element is designed to be activated by polarized light components with predetermined polarization characteristics and output the output. This output makes it possible to generate an image.

[0017] When the reference illumination light is irradiated onto the observation target (a catheter or its surrounding components (e.g., a blood vessel model)), it interferes with the observation target to obtain light components. Among these light components, the polarized components that match the polarization characteristics of the light-receiving unit are the polarized components imaged by the light-receiving unit. Specific examples of light components obtained through interference include (A) light obtained when polarized light (first polarization) is transmitted through the observation target as the reference illumination light. Another example of such light components is (B) light obtained when unpolarized light is reflected by the observation target. Furthermore, (C) scattered light, polarization, birefringence (including phase changes in polarization), and photofluorescence (sometimes collectively referred to as secondary light in the specification) generated by the observation target irradiated with the reference illumination light are also examples of such light components. When using reflected light or secondary light in the above cases, it is preferable to use light of a wavelength that is difficult to transmit through the sheath as the reference illumination light to avoid the influence of the wire inside the catheter. Alternatively, the influence of unnecessary light originating from the wire can be reduced or eliminated using a polarizing element, lens, filter, etc.

[0018] (3) Application of Visible Light Using a light-receiving unit with predetermined polarization characteristics allows for the utilization of reflected light and secondary light from the object of observation. When the inventors irradiated the object of observation with white visible light (wavelength: 380 nm to 700 nm) polarized in a first direction, the sheath was displayed on the screen, and the sheath and wire could be distinguished. This is thought to be due to the fact that even visible light penetrates the sheath, interferes with the sheath material, and emits secondary light containing a polarized component. When the polarization characteristics of the light-receiving unit were canceled, i.e., imaging was possible using all of the light received by the light-receiving unit (e.g., when the analyzer was omitted in a combination of an analyzer and a light receiver), and visible light polarized in the first direction (white light) or non-polarized visible light (white light) was irradiated onto the object of observation, the sheath could not be distinguished and observed. Without a light-receiving unit with polarization properties, the polarized components modulated by the sheath and imaged by the light-receiving unit and the light components that could not be imaged by the light-receiving unit are equally received, i.e., all light components of the reference illumination light are imaged by the light-receiving unit as light originating from the sheath. On the other hand, all light components of the reference illumination light originating from the materials surrounding the sheath are also imaged by the light-receiving unit, so there is no difference in light quantity between the two.

[0019] An image in which the sheath and the wire can be distinguished can also be generated when the light receiving unit is positioned so that it can receive the light reflected in whole or in part by irradiating the object with unpolarized white light. If the components surrounding the sheath have properties different from those of the sheath, such as the properties of generating polarized light or modulating the strength or direction of the polarized light, these components can be distinguished from the sheath and displayed on the image even when visible light is used.

[0020] As mentioned above, in the case of visible light, the sheath can be clearly distinguished from other components by visually observing the polarized light component that has passed through the analyzer, without using a photodetector or image generator. In this case, the output of the analyzer can be projected onto a display using an optical fiber or optical amplifier.

[0021] (4) Lantern Effect One way to highlight sheaths, which are difficult to detect (display in an image), is to increase the amount of light irradiated onto the sheath. While increasing the amount of light irradiated onto the object of observation, including the sheath, is of course feasible, there are limitations to the output of the light source due to issues such as the light source's rating and heat dissipation. Therefore, the inventors considered supplying auxiliary light to the sheath from the environment (material) surrounding the sheath. If this auxiliary light interferes with the sheath and generates a polarized component that is imaged by the light-receiving unit, the amount of light originating from the sheath increases, thereby making the sheath clearer in the image.

[0022] When the reference illumination light includes a first polarization, the auxiliary light is preferably polarized in the same state as the first polarization. Therefore, a material that causes Rayleigh scattering of the first polarization is dispersed in the surrounding components of the sheath (at least one of the material forming the vascular model, the immersion fluid, and the circulating fluid). This is because the Rayleigh-scattered polarized light maintains the same polarization state as the polarized light before scattering. Examples of materials that cause Rayleigh scattering include aqueous polymers such as PVA and surfactants. Adding these materials to the circulating fluid circulating through the vascular model improves its lubricity. The material that generates the auxiliary light is not limited to one that maintains the polarization state of the scattered light. It is sufficient for the material to emit secondary light toward the sheath by interfering with the irradiated reference illumination light, and for this secondary light to be modulated by the sheath to generate a polarized component that is imaged by the light-receiving unit. This secondary light is the auxiliary light.

[0023] In this specification, the illumination of the observation target with filler light is referred to as the "lantern effect." This lantern effect is particularly effective when illuminating the observation target with visible light. Since visible light cannot penetrate the sheath, reflected light and secondary light are the source of the sheath image generation. When reflected light is used, the area of ​​the sheath that reflects the reference illumination light is limited. Similarly, when secondary light is used, the area on the sheath where the reference illumination light, which is the source of generation, illuminates is limited. Thus, in either case, it is difficult to obtain a sufficient amount of light for the post-illumination light. Therefore, if visible light as filler light is illuminated from the periphery of the sheath onto the entire outer surface, it becomes possible to emit polarized components from the entire outer surface of the sheath that are imaged by the light-receiving unit, helping to ensure a sufficient amount of light.

[0024] (5) Light irradiated onto the object of observation (reference irradiated light) The above example is based on the concept when the relative angle between the polarization axis of the polarizing element and the polarization axis of the analyzer is 90 degrees. In this concept, if the crossing angle of the polarization axes is shifted from 90 degrees, some of the polarized light components that have not been modulated by the object of observation can pass through the analyzer. As a result, the amount of light that passes through the analyzer among the light originating from the sheath increases, and the sheath appears brighter. On the other hand, the contrast with the wire, which remains black because it does not allow light to pass through in the first place, becomes clearer.

[0025] The same applies when the polarizing element and analyzer are used for elliptically polarized light or circularly polarized light. Furthermore, the same applies when a polarization state with a spatial distribution (such as a polarization distribution dynamically generated by a photonic liquid crystal) or a polarization state that is a mixture of these is used. Expanding on this, it is preferable that the light irradiated onto the observation object (reference illumination light) contains at least a first polarization polarized in one direction. In other words, the reference illumination light may contain direct light from the light source (an unpolarized light component) or a polarization component polarized in a second direction different from the first polarization.

[0026] When polarized light is generated by reflection from an observation element, the reference illumination light does not necessarily need to contain polarized light. This does not preclude the reference illumination light from containing one or more types of polarized light. The wavelength of the reference illumination light is selected arbitrarily depending on the characteristics of the object being observed. A light-emitting unit that contains a polarized component in the reference illumination light is equipped with a light source and a polarizing element. The polarizing element has predetermined polarization characteristics (e.g., a polarization axis for linear polarization) and polarizes the light from the light source. This allows the light-emitting unit to irradiate the object being observed with polarized reference illumination light. In addition to using LEDs and bulbs as light sources, ambient light (sunlight or indoor lighting) can also be used as a visible light source. If the polarization characteristics of a device (photoelectric conversion element) that receives an electrical signal and outputs polarized light can be designed, this device can be used directly as the light-emitting unit. Reference illumination light containing only specific wavelengths contained in the light source can also be generated by using optical filters, lenses, etc.

[0027] (6) Light resulting from being irradiated onto the object of observation and subjected to interference from it (post-irradiation light) The reference irradiation light irradiated onto the object of observation interferes with the object of observation. When viewed from the light-receiving unit side, there are three types of interference: (A) light transmitted through the object of observation, (B) light reflected by the object of observation, and (C) secondary light generated by the object of observation (diffusion, polarization, phase change, fluorescence, etc.). In this specification, these lights are referred to as "post-irradiation light." The post-irradiation light includes a polarized component that is imaged by the light-receiving unit.

[0028] (7) Contrast Adjustment (Implementation of Vascular Roadmapping) Changing the polarization characteristics of the light-receiving unit (e.g., polarization axis direction) changes the brightness of each component displayed in the image. This is because the polarization components and their intensities contained in the post-irradiation light differ depending on the component. According to the inventors' studies, when the polarization angle of the first polarized light contained in the reference irradiation light is set to 90 degrees and the polarization axis of the light-receiving unit is set to 0 degrees, i.e., when the relative angle between the polarization axis of the polarizing element and the polarization axis of the light-receiving unit is 90 degrees, an image (Image 1-2) in which only the structure of the catheter can be recognized is generated by adjusting the wavelength and intensity of the reference irradiation light. On the other hand, when the relative angle between the polarization axis of the polarizing element and the polarization axis of the light-receiving unit is set to less than 90 degrees but greater than 45 degrees, it becomes possible to generate an image (Image 1-3) of components other than the catheter. By overlaying Image 1-2, for example, as a video, on Image 1-3, a simulation simulating the vascular roadmapping method is achieved.

[0029] (8) General Concept of the Principle of the Observation Device In (1), the principle of the observation device specified in the above aspect was explained as follows. If there is a difference between the amount of polarized components of light originating from the sheath and imaged by the light-receiving unit in the light receiving unit and the amount of polarized components of light originating from the material surrounding the sheath and imaged by the light receiving unit in the light receiving unit, the sheath can be displayed in a identifiable manner on the image. In this example, the image is generated based only on the polarized components imaged by the light receiving unit. However, if there is also a difference between the reference illumination light as a reference and the polarized components contained in the post-illumination light and imaged by the light receiving unit, the sheath can be displayed in a identifiable manner on the screen. That is, the observation output when the reference illumination light is directly received by the light receiving unit without any interference with the observation target is used as the reference output, and this is compared with the observation output when the post-illumination light is received by the light receiving unit. In other words, the observation principle of the observation device specified in the above aspect can be understood as determining a reference output and determining the difference in light intensity between the predetermined reference output and the observation output.

[0030] In light of the above findings, a first aspect of the present invention is defined as follows: An observation device for observing a blood vessel model into which a catheter is inserted, the observation device comprising: a light receiving unit having predetermined polarization characteristics, which receives and images a polarized component of post-illumination light that matches the predetermined polarization characteristics, wherein the post-illumination light is reference illumination light that is irradiated onto the observation object and has been subjected to interference from the observation object, and includes a polarized component that is imaged by the light receiving unit, the polarized component originating from a sheath of the catheter.

[0031] According to the observation device of the first aspect defined in this way, the polarized component originating from the sheath and contained in the post-illumination light is imaged by the light-receiving unit. On the other hand, by not including light originating from the catheter wire in the post-illumination light, it is possible to observe the wire and sheath with a difference in brightness. Furthermore, light originating from reflection or scattering at the interface between the components constituting the observation target contains almost no polarized component imaged by the light-receiving unit. As a result, such reflection or scattering has no effect on the image.

[0032] If the reference illumination light has a wavelength that can be transmitted through the sheath, the reference illumination light is blocked by the wire when it is transmitted to the object of observation, and therefore the light component originating from the wire is not included in the post-illumination light.If the reference illumination light has a wavelength that cannot be transmitted through the sheath, the reference illumination light does not reach the wire, and therefore the polarized component originating from the wire is not included in the post-illumination light.

[0033] When performing observation by reflecting the reference illumination light off the observation target, the reason why light originating from the wire can be prevented from being included in the post-illumination light is as follows. When the reference illumination light can pass through the sheath and the wire is made of a material that absorbs the reference illumination light, the reference illumination light is blocked by the wire, and therefore the light component originating from the wire is not included in the post-illumination light. When the wire is made of a material with a metallic luster, the reference illumination light interferes with the wire and is specularly reflected. In this case, the polarization state contained in the reference illumination light is substantially maintained even after reflection. Therefore, by receiving the reflected light obtained in this way as post-illumination light in the light-receiving unit, a brightness difference can be created between the wire and the sheath. In particular, by adjusting the polarization characteristics of the light-receiving unit, it is possible to adjust the amount of polarized components originating from the wire. This allows the brightness of the wire to be adjusted. If the wire has a metallic luster and its surface is covered with a resin or the like, the reflection from the metallic luster part inside the resin maintains the polarization as described above. In addition, the reflection from the surface of the resin or the like generates new polarization (the s-wave is reflected relatively more strongly than the p-wave), and the combined light of both is reflected. Therefore, by receiving the reflected light at the light receiving unit, it is possible to create a difference in brightness between the wire and the sheath.

[0034] In the observation device of the first aspect defined above, when the reference illumination light is visible light, the ambient light of the observation device can be used as the reference illumination light. The post-illumination light obtained by irradiating the observation object with this reference illumination light can include a polarized component imaged by the light-receiving unit. Of course, the reference illumination light can also include a first polarization. To make the reference illumination light include the first polarization, a light-emitting unit including a light source and a polarizing element is provided. The light source can output visible light and / or near-infrared light, and the polarizing element can polarize the light from the light source in any direction, such as linear polarization or circular polarization. The reference illumination light can be polarized in different directions in different regions by using a plate-shaped polarizing element with a diffraction grating or a photonic liquid crystal, or the polarization state can be dynamically changed overall or in different regions by controlling the photonic liquid crystal or providing a mechanical rotation function to the built-in wave plate. The reference illumination light generated by such a polarizing element will include multiple polarizations. Furthermore, by making a portion of the polarizing element plate transparent, the light from the light source can be included in the reference illumination light as is (unpolarized). It is also possible to use a photoelectric conversion element that outputs polarized light and generate reference illumination light containing a polarized component by electrical control (voltage control).

[0035] The polarizing element may be interposed between the light source and the object to be observed, or all or a part of it may be included in the object to be observed, or it may be included in a partial region or multiple regions of the object to be observed, for example, only the lower part of the blood vessel model. Similarly, the analyzer may be disposed outside the object to be observed, or all or a part of it may be included in the object to be observed, or it may be included in a partial region or multiple regions of the object to be observed, for example, only the upper part of the blood vessel model.

[0036] When the reference illumination light is visible light, an analyzer is used as the light receiving unit, and the output of the analyzer, i.e., the polarized components that have passed through the analyzer, can be seen as an image, allowing the observer to directly distinguish and observe the sheath and wire. When the light receiving unit is composed of an analyzer and a light receiver, the light (visible light, near-infrared light) that has passed through the analyzer is received by the light receiver, and an output (observation output) corresponding to the received polarized components is generated by the light receiver. The analyzer has an area that can receive the light components originating from the object of observation in the post-illumination light, and the light receiver has an array of light receiving elements that corresponds to the area of ​​the analyzer. An optical filter, a lens, a second polarizing element, and a second analyzer can be arranged between the object of observation and the analyzer and / or between the analyzer and the light receiver.

[0037] The light-emitting unit and the light-receiving unit make up the observation assembly. The observation output from the light-receiving unit is converted into an image by the image generating unit, and this image is displayed on a display. The image generating unit and the display make up the image display assembly. When the light-receiving unit is made up of a photoelectric element, the output of the photoelectric element is sent to the image generating unit as the observation output. This element receives polarized light components with predetermined polarization characteristics and outputs an electrical signal.

[0038] From the above, a second aspect of the present invention is defined as follows: The observation device defined in the first aspect further comprises a light-emitting unit and an image display assembly, wherein the light-receiving unit and the light-emitting unit constitute an observation assembly, the light-emitting unit irradiates the reference illumination light toward the observation object, the reference illumination light including a first polarized light, the light-receiving unit receiving the post-illumination light generates an observation output corresponding to the polarization component to be imaged, the image display assembly comprises an image generation unit and a display, the image generation unit generates an image based on the observation output, and the display displays the image.

[0039] A third aspect of the present invention is defined as follows: The observation device according to the second aspect, wherein the image generation unit generates an image based on a comparison of the observation output with a reference output from the light receiving unit that receives the reference irradiation light that does not interfere with the object of observation. According to the observation device of the third aspect defined in this way, the reference output from the reference irradiation light is used as a base to compare with the observation output, so that disturbances in the observation output due to changes in the observation environment are offset, resulting in a more stable generated image, compared to when an image is generated simply from the observation output alone. For example, even if ambient light is incident, this is also treated as reference irradiation light.

[0040] In the observation device of the third aspect, the reference output is an output when the light receiver with the polarization characteristic canceled receives the reference irradiation light that does not interfere with the observation object, and the light receiving unit has a polarization axis in a direction different from the first direction as the polarization characteristic, and the light receiving unit can generate an observation output according to the polarization component imaged by the light receiving unit (fourth aspect). In the observation device of the fourth aspect, the amount of light of the polarization component that has passed through a specific polarization axis provided in the light receiving unit becomes the observation output, and this is compared with the reference output to form an image.

[0041] In addition, in the observation device of the third aspect, the reference output is an output of the light receiving unit that receives the reference irradiation light that does not interfere with the observation object as the post-irradiation light, and the light receiving unit generates an observation output corresponding to a component of the polarization direction of polarized light contained in the received post-irradiation light (fifth aspect).

[0042] In the observation device of the fifth aspect, since the light receiving unit can detect components in the polarization direction, the count is set to 1 when the light receiving unit receives the first polarized light in the first direction of the reference illumination light, and the count is set to n when the light receiving unit assumes that the polarization components contained in the post-illumination light have n polarization directions. An observation output is generated based on the comparison result between the two (e.g., the difference n-1). This generates an image that reflects the type of polarization component (based on the polarization direction) generated by modulating the first polarized light. In other words, the image is generated based on the degree of polarization of the polarization component contained in the post-illumination light relative to the first polarized light. Here, an example is shown in which n polarization states are detected for reference illumination light of one polarization state. Similar detection can also be performed even if the reference illumination light includes polarization of n polarization states.

[0043] The above-mentioned lantern effect can be used to highlight sheaths on an image. A sixth aspect of the present invention is an observation device utilizing the lantern effect, which is specified as follows: the observation device according to the first aspect, comprising: an observation target assembly including the observation target, a circulating fluid circulating through the blood vessel model, and an immersion fluid in which the observation target is immersed, wherein a secondary light generating material that interferes with the reference illumination light to generate secondary light is dispersed in at least one selected from a constituent material of the blood vessel model, the immersion fluid, and the circulating fluid, and the secondary light interferes with at least the sheath to emphasize a polarization component originating from the sheath in the post-illumination light.

[0044] The secondary light is preferably polarized in the same direction as the first polarized light contained in the reference light. Therefore, the secondary light-generating material dispersed in the immersion liquid and the circulating liquid is configured to cause Rayleigh scattering of the reference light (aspect 7). The secondary light-generating material that causes Rayleigh scattering can be a water-soluble polymer and / or a surfactant (aspect 8).

[0045] Another method for highlighting the sheath on an image is as follows. That is, the light absorption characteristics and polarization characteristics of the materials surrounding the blood vessel model are made different from the light absorption characteristics and polarization characteristics of the sheath. Therefore, a ninth aspect of the present invention is defined as follows: The observation device according to the second aspect, wherein the immersion liquid and / or the circulating liquid have light absorption characteristics and / or polarization characteristics for the reference irradiation light that differ from those of the blood vessel model. The light absorbed here is all or a part of the light components of the reference irradiation light and the post-irradiation light. As a substance that changes the polarization characteristics, for example, sucrose, maltose, etc., which cause optical rotation, can be used.

[0046] A tenth aspect of the present invention is defined as follows. The observation device according to the second aspect, wherein the material forming the blood vessel model generates a photoelastic effect with respect to the reference irradiation light, and light generated by the photoelastic effect is included in the post-irradiation light. Stress is generated in the material forming the blood vessel model, causing a photoelastic effect, and the light generated as a result becomes part of the post-irradiation light. This light may include a polarized component that is imaged by a light-receiving unit. This allows the photoelastic effect to be reflected in the image. A separate light-receiving unit may be provided that is dedicated to receiving light resulting from the photoelastic effect.

[0047] An eleventh aspect of the present invention is defined as follows: the observation device according to the second aspect, wherein the observation target assembly further comprises a plate for holding the blood vessel model, the plate transmits the reference illumination light, the plate has a groove that follows the shape of the blood vessel model, and the blood vessel model is fitted into the groove completely or partially without any gaps. Use of such a plate makes it easy to set and replace the blood vessel model.

[0048] By generating a photoelastic effect in the material of the peripheral wall of the groove into which the blood vessel model is fitted, stress generated in the material forming the blood vessel model can be transmitted to the material of the plate, where the photoelastic effect can be exerted. Therefore, a twelfth aspect of the present invention is defined as follows: The observation device according to the eleventh aspect, wherein the peripheral wall of the groove in the plate is formed of a soft material that generates a photoelastic effect with respect to the reference irradiation light, and light generated by the photoelastic effect is included in the post-irradiation light.

[0049] In actual catheter surgery, an operation to remove a blood clot or the like from a blood vessel is performed. In order to simulate such an operation, a thirteenth aspect of the present invention is defined as follows: The observation device according to the second aspect, wherein the blood vessel model in the observation target assembly has a movable part simulating a blood clot or the like disposed inside the blood vessel model, and the movable part interferes with the reference illumination light to modulate its polarization state.

[0050] The observation device of the present invention is used as a simulator for catheter surgery. In such a usage mode, it is required to display images similar to those in actual catheter surgery. Therefore, the observation device of a fourteenth aspect of the present invention is specified as follows: The observation device according to the second aspect, wherein the observation assembly is capable of capturing images of a first region of the observation object and a second region different from the first region. To observe different regions of the observation object in this manner, at least one of the light-emitting unit and the light-receiving unit of the observation object assembly is moved relative to the observation object, or the optical axis of the reference radiation light emitted from the light-emitting unit is polarized.

[0051] In recent years, so-called biplane observation has been performed on catheter operating tables. To emulate such biplane observation, a fifteenth aspect of the invention is specified as follows: The observation device according to the fourteenth aspect further includes a second observation assembly having a second light-emitting unit and a second light-receiving unit, and the second observation assembly observes the region of the observation object observed by the observation assembly from another direction. The observation assembly and the second observation assembly can be movable relative to the observation object (sixteenth aspect). Here, the second light-emitting unit and the second light-receiving unit perform the same functions as the light-emitting unit and the light-receiving unit of the observation assembly, and supply an observation output to an image generation assembly.

[0052] A seventeenth aspect of the present invention is defined as follows: The observation device according to the first aspect, wherein the light receiving unit is disposed at one or more of the following positions: a first position capable of mainly receiving post-illumination light formed when the reference illumination light is transmitted through the observation object; a second position capable of mainly receiving post-illumination light formed when the reference illumination light is reflected by the observation object; and a third position capable of mainly receiving secondary light generated when the reference illumination light interferes with the observation object. For example, by disposing the light receiving unit at multiple positions, the sheath can be observed more reliably. This is because the transmission characteristics, reflection characteristics, etc., may differ depending on the sheath material.

[0053] An 18th aspect of the present invention is defined as follows: The observation device according to the 11th aspect, wherein the observation target assembly includes a case for holding the immersion liquid, the case constituting a part of a mannequin, and the plate is disposed within the case. With the observation device of the 18th aspect defined in this way, observation can be performed more realistically.

[0054] A nineteenth aspect of the present invention is defined as follows: The observation device according to the second aspect, wherein the observation target assembly includes a case that holds the immersion liquid, and a peripheral wall of the case includes the light-emitting portion. According to the observation device of the nineteenth aspect defined in this way, the device is simplified.

[0055] A twentieth aspect of the present invention is defined as follows: The observation device according to the second aspect, wherein the observation object assembly includes a case for holding the immersion liquid, and the case is provided with an anti-reflection section for the reference irradiation light on the side of the light-emitting section. According to the observation device of the twentieth aspect defined in this way, the influence of the reference irradiation light reflected by the observation object inside the case can be eliminated, resulting in a clear image.

[0056] A 21st aspect of the present invention is defined as follows: The observation device according to the 20th aspect, in which the object to be observed is unevenly distributed toward the light-receiving unit within the case, so that the layer of immersion liquid between the object to be observed and the light-emitting unit is thicker than the layer of immersion liquid between the object to be observed and the light-receiving unit, and the layer of immersion liquid between the object to be observed and the light-emitting unit functions as the anti-reflection unit. According to the observation device of the 21st aspect defined in this way, the influence of irradiated light reflected by the object to be observed can be eliminated by adjusting the position of the blood vessel model within the case, resulting in a simple device configuration.

[0057] A 22nd aspect of the present invention is defined as follows: An observation device according to the 2nd aspect, wherein a fluorescent material that emits a polarized component that is imaged by the light receiving unit is attached to a component of the observation target assembly, and the observation assembly includes a light source that causes the material to fluoresce. According to the observation device defined in the 22nd aspect, marks or characters can be written on the observation target with fluorescent paint, allowing for smooth observation operations. The light from the fluorescence includes a polarized component that is imaged by the light receiving unit.

[0058] A 23rd aspect of the present invention is defined as follows: The observation device according to the 22nd aspect, wherein the observation target assembly includes a case that holds the immersion liquid, the light is ultraviolet light, and the ultraviolet light from the light source is introduced into the case and emitted from a side wall of the case toward the observation target. According to the observation device defined in the 23rd aspect, visible light or near-infrared light is used as the reference irradiation light, and because the light used here is ultraviolet light, there is no disturbance to the reference irradiation light. Furthermore, because the case functions as a light source, the device can be simplified.

[0059] Since the roadmapping method is used in actual catheter surgery, it is preferable to simulate the roadmapping method in simulations using this observation device. Therefore, a 24th aspect of the present invention is defined as follows: The observation device according to the second aspect, wherein the light receiving unit has a second polarization characteristic state and a third polarization characteristic state in a direction relatively different from the first direction of the first polarization, the image display assembly has an image synthesis unit, the light receiving unit generates an observation output that generates a first-second image when in the second polarization characteristic state, and the light receiving unit generates an observation output that generates a first-third image when in the third polarization characteristic state, the image synthesis unit synthesizes the first-second image and the first-third image, and the display displays the synthesized image. Here, the second polarization characteristic state and the third polarization characteristic state of the light receiving unit can be obtained by adjusting the polarization characteristics of the light receiving unit itself. Furthermore, they can also be obtained by adjusting the polarization direction of the first polarization of the reference irradiation light, either in conjunction with or independently of this adjustment.

[0060] In the observation device of the 24th aspect, the 1-2 image displays only the catheter sheath and the metal linear object within the sheath, and the 1-3 image displays the blood vessel model (25th aspect), thereby enabling simulation of the roadmap method. In particular, it is preferable that the 1-2 image is a moving image (26th aspect). The 1-3 image can display the catheter in addition to the blood vessel model. Furthermore, when a polarization camera or the like in which polarization elements are arranged in an array with different states for each pixel is used, multiple polarization characteristic states can be simultaneously detected in real time without physical operation. As a result, the 1-2 image, the 1-3 image, and composite images thereof (such as roadmap images and images with unnecessary reflected light removed) can be easily, freely, and in real time by software processing.

[0061] A 27th aspect of the present invention is an observation method using the observation device defined in the first aspect, which is defined as follows: An observation method using an observation device whose observation object is a blood vessel model into which a catheter is inserted, the observation method using an observation device having a light-receiving unit with predetermined polarization characteristics, the observation method including the steps of: irradiating the object with reference illumination light; receiving, by the light-receiving unit, post-illumination light generated by the reference illumination light that has received interference from the object of observation, wherein the post-illumination light includes a polarized component that originates from a sheath of the catheter; and generating an output based on the polarized component that matches the polarization characteristic of the polarized component originating from the sheath and is imaged by the light-receiving unit.

[0062] A 28th aspect of the present invention is defined as follows: The observation method according to the 27th aspect, wherein a secondary light generating material that interferes with the reference illumination light to generate secondary light is dispersed in at least one selected from a constituent material of the blood vessel model, a lubricating liquid circulating within the blood vessel model, and an immersion liquid in which the blood vessel model is immersed, and the polarization component of the post-illumination light is changed by causing the secondary light to interfere with the sheath.

[0063] A 29th aspect of the present invention is defined as follows. The observation method according to the 27th aspect, wherein the light receiving unit has a second polarization characteristic state and a third polarization characteristic state in a direction relatively different from the first direction of the first polarization, and the contrast between the catheter sheath and its surroundings displayed in the image is adjusted by adjusting the second polarization characteristic state and the third polarization characteristic state. According to the observation method of the 29th aspect defined in this way, the contrast is adjusted by adjusting the second polarization characteristic state and the third polarization characteristic state of the light receiving unit. Therefore, it is possible to display only the catheter or only the blood vessel model on the image.

[0064] A 30th aspect of the present invention is defined as follows: The observation method according to the 29th aspect, including the steps of: generating a contrast mode image in which only the sheath of the catheter and the metal linear object inside the sheath are displayed in the second polarized light receiving state; obtaining a still image mode image in which a blood vessel model is displayed in the third polarized light receiving state; and displaying the still image mode image and the contrast mode image in an overlapping manner.

[0065] A thirty-first aspect of the present invention is defined as follows: A cassette used in an observation device that irradiates an observation object with reference illumination light that interferes with a catheter sheath, the cassette incorporating the blood vessel model, the cassette comprising: the blood vessel model; a housing that holds the blood vessel model; and a polarizing element that is arranged between the blood vessel model and the light source. Use of such a cassette makes it easy to set the observation object.

[0066] A thirty-second aspect of the present invention is defined as follows: A plate for holding a catheter in an observation device for observing a blood vessel model with a catheter inserted therein, the plate having a groove that follows the shape of the blood vessel model, and a peripheral wall of the groove making full or partial contact with the blood vessel model without any gaps. By using such a plate, the blood vessel model can be stably held, allowing for smooth observation work.

[0067] A 33rd aspect of the present invention is defined as follows: A plate according to the 32nd aspect, wherein the peripheral wall of the groove is formed of a soft material that generates a photoelastic effect. Because the blood vessel model is tightly fitted into the groove and in contact with it, deformation of the blood vessel model imparts stress changes to the soft material of the plate, thereby generating a photoelastic effect. In other words, the degree of deformation of the blood vessel model when the catheter interferes with the blood vessel model can be observed as a photoelastic effect in the groove wall of the plate that contacts the deformed portion of the blood vessel model.

[0068] A 34th aspect of the present invention is defined as follows: An observation device for observing a blood vessel model into which a catheter is inserted, comprising: an observation assembly including a light-emitting unit and a light-receiving unit; and an image display assembly including an image generating unit and a display, wherein the light-emitting unit has a light source and a polarizing element and irradiates reference illumination light including a first polarized light toward the observation object, the polarizing element has a polarization axis in a first direction and transmits the first polarized light polarized in the first direction out of the light output from the light source, the first polarized light passes through a sheath of the catheter and the polarization state of at least some of its light components is modulated, the light-receiving unit has a light receiver and an analyzer, the analyzer has a polarization axis in a second direction different from the first direction, and the light receiver receives a light component that has passed through the analyzer out of the reference illumination light (post-irradiation light) that has been irradiated to the observation object and has experienced interference from the observation object, and generates an observation output, the image generating unit receives the observation output and generates an image, and the display displays the image.

[0069] The sheath of an actual catheter has a multilayer structure of thin polymer films, but the materials and thicknesses of the films that make up the sheath vary depending on the type of catheter. Various soft resins, such as polyester, polyethylene, polyamide, polyurethane, and silicone rubber, are used as materials for the thin films that make up the sheath. Furthermore, the catheter wire incorporates complex metal structures, such as mesh and radiopaque markers, as well as mechanical structures, such as a balloon and coil detachment mechanism. For catheters with these characteristics, the present invention makes it possible to clearly capture images of the wire within the sheath using typical near-infrared light and newly discovered visible light, without using X-rays. This allows for the acquisition of images similar to those obtained during actual catheter surgery using X-rays.

[0070] FIG. 1 is a block diagram showing the configuration of an observation device according to an embodiment of the present invention. FIG. 2 is a perspective view of the observation device according to the example. FIG. 3 is a partial perspective view showing a plate of an observation target assembly. FIG. 4 shows a case containing the plate of FIG. 3. FIG. 5 illustrates the photoelastic effect. FIG. 6 is an image of an observation target taken by the observation device according to the example of FIG. 2. FIG. 7 is a block diagram showing an observation device according to another embodiment. FIG. 8 is a block diagram showing an observation device according to another embodiment. FIG. 9 is a block diagram showing an observation device according to another embodiment. FIG. 10 is a block diagram showing an observation device according to another embodiment. FIG. 11 is an image of an observation target taken by the observation device of FIG. 10. FIG. 12 is a block diagram showing an observation device according to another embodiment. FIG. 13 is a block diagram showing an observation device according to another embodiment. FIG. 14 is a block diagram showing an observation device according to another embodiment. FIG. 15 is an image of an observation target taken by the observation device of FIG. 14. FIG. 16 is an image of a comparative example. FIG. 16 is a block diagram showing an observation device according to another embodiment.

[0071] An observation device A according to an embodiment of the present invention will now be described with reference to Figure 1. This observation device A comprises an observation target assembly 1, an observation assembly 20, and an image generation assembly 30. The observation target assembly 1 comprises a catheter 2, a blood vessel model 5, a circulating fluid 6, an immersion fluid 7, and a case 8. The catheter 2 has a sheath 3 made of soft resin into which an irradiated light-opaque member (hereinafter referred to as "wire") made of a metal linear body such as a wire 4 is inserted. Catheterization technique training requires participants to grasp the position of the tip of the wire 4 within the sheath 3. An actual catheter 2 can be used as is.

[0072] The vascular model 5 is formed to resemble human blood vessels and can be formed, for example, from soft silicone rubber using the so-called lost wax method. For a method of manufacturing the vascular model, see the description in Japanese Patent No. 3613568, the disclosure of which is incorporated herein by reference. A material that causes Rayleigh scattering in the near-infrared light 9, which is the reference irradiation light, can be added to the constituent materials of the vascular model. Examples of materials that cause Rayleigh scattering include silicone rubber containing silica particles and PVA gel.

[0073] Furthermore, the material constituting the blood vessel model can be added with a material that changes the scattering state of near-infrared light passing through the blood vessel model when stress is applied to the blood vessel model, thereby producing a photoelastic effect. Examples of such materials include gelatin and polyurethane rubber. Furthermore, a movable part simulating a blood clot can be placed inside the blood vessel model. This movable part can be made of the same material as the material constituting the blood vessel model, but it may also be made of another soft material.

[0074] This movable part can include at least one of a material that scatters polarized near-infrared rays 9, a material that modulates the polarization state of near-infrared rays 9, and a secondary light-emitting material that receives the near-infrared rays 9 and generates secondary light. Materials that change the scattering state can include the aforementioned materials that cause Rayleigh scattering, as well as silica particles or colloids with a particle size that cause Mie scattering. Materials that modulate the polarization state can include cellulose, maltose, and the like that cause optical rotation. Materials that absorb near-infrared rays and exhibit fluorescence, diffraction, birefringence, or the like are selected as the secondary light-emitting material.

[0075] The circulating fluid 6 fills the blood vessel model 5 and preferably flows within the blood vessel model 5 to simulate human blood flow. The circulating fluid 6 makes it easier for the catheter 2 to slide along the inner wall of the blood vessel model 5, and it is preferable that the resistance when inserting the catheter 2 into the blood vessel model 5 be the same as that when inserting into a human blood vessel.

[0076] The circulating fluid 6 may be a dispersion medium containing water and a water-soluble polymer, the water-soluble polymer having both hydrophilic and hydrophobic groups, and / or a mixture of a polymer having hydrophilic groups and a polymer having hydrophobic groups. The contents of PCT / JP2024 / 036297 are incorporated herein by reference.

[0077] It is preferable to use a circulating fluid 6 that has absorption characteristics for near-infrared rays 9 that differ from those of the constituent material of the blood vessel model. This is to clearly define the boundary between the circulating fluid 6 and the inner shell (inner peripheral surface) of the blood vessel model 5. Like the constituent material of the blood vessel model 5, the circulating fluid 6 can contain at least one of a material that changes the scattering state of near-infrared rays 9, a material that modulates the polarization state, and a secondary light-emitting material that receives the irradiated light and emits secondary light. This secondary light serves as auxiliary light, creating a lantern effect.

[0078] The immersion liquid 7 is filled in the case 8, and the blood vessel model 5 is immersed therein. It is preferable to use an immersion liquid 7 that has absorption characteristics for near-infrared rays 9 that differ from those of the material constituting the blood vessel model. This is to clearly define the boundary between the circulating fluid 6 and the outer periphery (outer surface) of the blood vessel model 5. Like the material constituting the blood vessel model 5, the immersion liquid 7 can contain at least one of a material that changes the scattering state of near-infrared rays 9, a material that modulates the polarization state, and a secondary light-emitting material that receives the irradiated light and emits secondary light. This secondary light serves as auxiliary light, creating a lantern effect. Depending on the observation environment, the immersion liquid may be omitted from the observation target assembly 1.

[0079] 1, the blood vessel model 5 is placed near the upper side of the case 8. This creates a relatively thick layer of immersion liquid 7 between the bottom wall of the case 8 and the blood vessel model 5. By providing such a thick layer of immersion liquid 7, near-infrared rays reflected by the object of observation consisting of the blood vessel model 5 and the catheter 2 are absorbed, and the reflected near-infrared rays are prevented from being reflected by the bottom wall of the case 8 or a first polarizing plate 23 described below.

[0080] The distance between the interface (top surface) of the blood vessel model 5 and the immersion liquid 7 is preferably short. This is to prevent absorption of near-infrared rays by the immersion liquid 7. Therefore, it is preferable that the distance from the bottom wall of the case 8 to the blood vessel model 5 is longer than the distance from the blood vessel model 5 to the surface of the immersion liquid. Alternatively, reflection of near-infrared rays can be prevented by covering the bottom surface of the case 8 with a film that is semi-transparent to near-infrared rays. The first polarizing plate 23 may also be provided with an anti-reflection function.

[0081] The observation assembly 20 includes a light-emitting unit 20A and a light-receiving unit 20B. The light-emitting unit 20A includes a light amount adjustment device 21, a near-infrared light source 22, and a first polarizing plate 23. The light-receiving unit 20B includes a second polarizing plate 24 and a near-infrared camera 25. The light amount adjustment device 21 adjusts the amount of near-infrared light emitted from the near-infrared light source 22. The light amount can also be adjusted by adjusting the aperture of the near-infrared camera 25.

[0082] Near-infrared rays 9 are emitted in the direction of the arrow from a near-infrared light source 22. This light source 22 is a surface light source that can cover at least a predetermined area of ​​the blood vessel model 5, which is the object of observation. Based on the experience of the inventors, the wavelength of the irradiated light emitted from the near-infrared light source 22 can be set to 700 to 1500 nm.

[0083] The first polarizing plate 23 as a polarizing element and the second polarizing plate 24 as an analyzer are both arranged on the optical axis of the near-infrared light 9 and have polarization axes in different directions. They can also be given the function of circular polarization or elliptically polarization. In the example of FIG. 1 , the crossing angle between the polarization axis of the first polarizing plate 23 and the polarization axis of the second polarizing plate 24 is set to 90 to 45 degrees. By adopting such a crossing angle, some of the polarized components (first polarized light) of the near-infrared light 9 polarized by the first polarizing plate 23 can pass through the second polarizing plate 24 as is, thereby making it possible to image the entire object to be observed.

[0084] On the other hand, when a part of the first polarized light is modulated by scattering at the object of observation, some of the polarized components therein have a polarization direction that matches the polarization axis of the second polarizer 24. Such polarized components pass through the second polarizer 24 without fail, and are therefore reflected without fail in the image displayed on the display 29.

[0085] The near-infrared camera 25 serving as a light receiver is placed on the optical axis of the near-infrared light 9, which is the reference irradiation light. The image generation assembly 30 includes an image generation unit 31 and a display 33. Data captured by the infrared camera 25 is sent to the image generation unit 31, and a general-purpose image generation program generates image data that can be displayed on the display 33. The near-infrared camera 25 may be equipped with an analyzer as an integral part. The same applies to the visible light camera described below.

[0086] 2 shows an observation device of the embodiment. In the observation device of the embodiment, a near-infrared camera 125 is supported on a support 126 via a position and orientation adjustment unit 127. A second polarizing plate 124 is attached immediately before the objective lens of the camera 125. A first polarizing plate is disposed below the observation target assembly 101 (not shown). An image generating unit (not shown) is connected to the camera 125. This image generating unit includes a general-purpose computer device and generates image data based on a signal from the camera 125. The generated image data is sent to a display device (not shown) and displayed thereon.

[0087] The observation target assembly 101 is roughly composed of a blood vessel model 105, a case 108, and a plate 110. The catheter is omitted. The catheter is inserted when observation is performed. The blood vessel model 105 is fitted tightly into the peripheral wall of a groove 111 formed on the upper surface of the plate 110. Reference numeral 121 denotes the inlet of the catheter connected to the blood vessel model 105, and is provided with an inlet 123 for the circulating fluid on the side. Reference numeral 125 denotes the outlet for the circulating fluid.

[0088] The plate 110 is supported by a partition plate 113, which is fixed to the inner side wall of the case 108. The partition plate 113 is disposed toward the upper side of the case 108. This ensures a large space between the plate 110 (i.e., the blood vessel model 105) and the bottom wall of the case 108. By filling this space with immersion liquid, near-infrared rays reflected by the blood vessel model 105 can be absorbed.

[0089] Fig. 3 is a perspective view showing the state of the blood vessel model 105 attached to the plate 110, and the set shown in Fig. 3 is stored in a case 108 as shown in Fig. 4. Fig. 5 shows the state in which the blood vessel model with a catheter inserted is fitted into the groove of the model holder (plate). The upper view of Fig. 5 shows the state in which there is no irradiation of near-infrared rays 9 polarized by the first polarizing plate, and the lower view of Fig. 5 shows the state in which there is irradiation of polarized near-infrared rays 9.

[0090] The model holder (plate) is made of a soft polymeric material, such as urethane elastomer. As can be seen from the bottom diagram, when the pressure on the blood vessel model by the catheter deforms the blood vessel model, the wall surface of the groove in the model holder (plate) also deforms accordingly. The stress in the deformed area generates a photoelastic effect.

[0091] The specifications of the observation device in this example are as follows: Catheter: Excelsior microcatheter, model number: 1080, manufactured by Stryker Blood vessel model: Made of silicone rubber, provided by Fine Biomedical, Inc. Circulating fluid: Circulating fluid (model number: BIOACT[A]) provided by Fine Biomedical, Inc., diluted 500 times with water Immersion fluid: 0.8 wt% polyvinyl alcohol (manufactured by Kanto Chemical Co., Inc., model number: Polyvinyl Alcohol 2000) dissolved in 100 parts by volume of water Near-infrared light source: 940 wavelength LEDs, densely arranged in an area of ​​200 mm x 200 mm. First polarizer and second polarizer: near-infrared polarizer (wire grid polarizer manufactured by Asahi Kasei Corporation, model number: WGF) Crossing angle of polarization between the first polarizer and the second polarizer: 30 degrees Near-infrared camera (polarized camera): manufactured by Sony Corporation, model number: XCG-CP510 Image formation software: The image software included with the near-infrared camera is incorporated into the computer constituting the image generation unit 31. Display: general-purpose product Distance between plate 110 and bottom wall of the case: 60 mm

[0092] The polarization camera (manufactured by Sony Corporation, model number: XCG-CP510) has polarizers (analyzers) arranged in an array, with each pixel having a different state, allowing for real-time acquisition of diverse information regarding the polarization state (at least three of the four Stokes parameters required to identify the polarization state). Furthermore, by using software processing, the acquired information regarding the polarization state (Stokes parameters) can be freely subjected to numerical calculations (e.g., addition, subtraction, multiplication, etc.). As a result, it is possible to extract the intensity and direction of the polarization component, the degree of polarization, the degree of birefringence (the photoelastic effect, i.e., the magnitude of internal stress), detect or remove only the unpolarized component, detect or remove only the reflected component, and even identify the shape of the object being observed. In the applications of the present invention, the use of this polarization camera allows, for example, the aforementioned contrast adjustment (adjusting the degree of fusion of the interference and non-interference components in the sheath section) and procedures associated with the roadmap method to be achieved solely through software processing, without the need for physical means or operations.

[0093] An example of an image taken by the observation device of the embodiment is shown in Figure 6. From the results of Figure 6, it is clear that the wire can be clearly seen inside the sheath of the catheter 202 when the observation device of the embodiment is used.

[0094] Fig. 7 shows an observation device B according to another embodiment. In Fig. 7, the same elements as those in Fig. 1 are designated by the same reference numerals, and their description will be omitted. The image display unit 130 of the observation device B in Fig. 7 includes a background image storage unit 41, an image synthesis unit 43, an image evaluation unit 45, and a guidance generation unit 47, in addition to the image generation unit 31 and the display 33. The background image storage unit 41 stores a background image showing bones and other tissues, and the image synthesis unit 43 can synthesize this background image with an image captured by the near-infrared camera 25 and display it.

[0095] The image evaluation unit 45 evaluates the photoelastic effect shown in Fig. 5 using, for example, AI. The evaluation result of the image evaluation unit 45 is sent to the guidance generation unit 47. Based on this evaluation result, the guidance generation unit 47 generates guidance in, for example, text format and displays it on the display 33.

[0096] In actual catheter-based intravascular surgery, the administered contrast agent is washed away by the bloodstream, so blood vessels are only visible for a few seconds. Furthermore, due to its toxicity, there is a limit to the amount of contrast agent that can be used, and it cannot be administered multiple times. For this reason, a technique known as vascular roadmapping is used in which the image of the blood vessels visualized at the moment the contrast agent is administered is saved as a still image and then superimposed on an image that visualizes only the catheter.

[0097] Using the observation device of the present invention, the vascular roadmapping method can be simulated as follows: First, a still image in which the vascular model is visualized is saved. Then, by changing the observation conditions, the image of the vascular model disappears and an image in which only the catheter is visualized is saved. These two images are then superimposed. In simulating the vascular roadmapping method, it is preferable to further equip the observation device of the present invention with a hardware interface such as a foot pedal or joystick, so that various operations associated with the image processing can be performed in a manner similar to that of actual catheter-based intravascular surgery.

[0098] FIG. 8 is a block diagram showing the configuration of an observation device C that performs the vascular roadmapping method. Elements identical to those in FIG. 1 are designated by the same reference numerals and will not be described further. The image generation assembly 230 of this observation device C includes an image generation unit 31, a display 33, an image synthesis unit 43, and an image storage unit 51. In this example, the second polarizer 24 is rotated relative to the first polarizer 23 to change the relative angle of the polarization axes of the two polarizers. This changes the observation conditions, and when the relative angle of the polarization axes of the two polarizers is set to a second angle (second polarization characteristic state) and a third angle (third polarization characteristic state), the intensity of the light source 22 and the wavelength of the near-infrared light 9 are further adjusted. A first-2 image, in which only the catheter is visualized, is generated and stored in the image storage unit 51. Similarly, a first-3 image, in which the vascular model is visualized, is generated and stored in the image storage unit 51. The first-2 image is converted into a video, and the image synthesis unit 43 synthesizes this first-2 image with the first-3 image, thereby performing an observation simulating the vascular roadmapping method.

[0099] As another method for implementing the roadmap method, a solution that affects the polarization component of the circulating fluid can be introduced into the circulating fluid as a contrast agent to capture still images that primarily display a vascular model, corresponding to images 1-3. Examples of such solutions include solutions that absorb the reference illumination light (such as a liquid containing India ink or aluminum powder) and solutions that change its polarization state (such as milk, which depolarizes light by scattering, or an aqueous solution (sugar water) containing cellulose or maltose by optical rotation).

[0100] An observation device D according to another embodiment of the present invention is shown in FIG. 9. In FIG. 9, elements identical to those in FIG. 1 are designated by the same reference numerals, and their description will be omitted. In addition to the display 33, the image display assembly 330 of this observation device D includes an image generation unit 231, a reference output storage unit 61, and an observation output storage unit 63. The reference output stored in the reference output storage unit 61 is output data from the near-infrared camera 25 when the second polarizer 24 is removed. The observation output stored in the observation output storage unit 63 is output data from the near-infrared camera 25 of the polarized light component that has passed through the second polarizer. The reference output may be acquired and stored in advance as a baseline before the start of observation, or may be acquired each time observation is performed. The image generation unit 231 compares the reference output with the observation output, and more specifically, calculates the difference in light intensity between the two, and sends the result to the display 33 as image data.

[0101] FIG. 10 shows an observation device E according to another embodiment of the present invention. In FIG. 10, elements that are the same as those in FIG. 1 are given the same reference numerals, and their description will be omitted. The observation assembly 120 of this observation device E handles visible light (white light). The light-emitting unit 120A of the observation assembly 120 includes a white light source 122A and a first polarizing plate 123 consisting of a polarizing element for visible light. The light-receiving unit 120B includes a visible light camera 125B and a second polarizing plate 124B consisting of an analyzer for visible light. An observation test was conducted using the specifications of each element constituting the observation device E configured as described above, except for the near-infrared light source. A point light source was used as the white light source. The observation results are shown in FIG. 11.

[0102] An observation device F according to another embodiment of the present invention is shown in Figure 12. In Figure 12, the same elements as in Figure 1 are given the same reference numerals, and their description will be omitted. In the observation assembly 220 of this observation device F, polarized near-infrared light 9, which is the reference irradiation light from the light-emitting unit 220A, is irradiated obliquely onto the observation target 1, and the light-receiving unit 20B is not present at the end of the optical axis. The light component of the post-irradiation light that reaches the light-receiving unit 20B is mainly secondary light 9a from the observation target.

[0103] An observation device G according to another embodiment of the present invention is shown in Figure 13. In Figure 13, elements that are the same as those in Figure 1 are given the same reference numerals, and their description will be omitted. In an observation assembly 320 of this observation device G, a light-emitting unit 320A and a light-receiving unit 20B are arranged on the same side. Polarized near-infrared light 9, which is reference irradiation light, is irradiated obliquely from the light-emitting unit toward the observation target 1, and the light-receiving unit 20B is not located at the end of the optical axis. The post-irradiation light that reaches the light-receiving unit 20B is mainly reflected light 309c, and this reflected light 309c contains a polarized component.

[0104] An observation device H according to another embodiment of the present invention is shown in Figure 14. In Figure 14, elements identical to those in Figure 10 are designated by the same reference numerals, and their description will be omitted. In the observation assembly 420 of this observation device H, a light-emitting unit 420A is disposed on the same side as the light-receiving unit 120B, and white light 409 is irradiated from the light-emitting unit 420 onto the observation object as reference irradiation light without being polarized in any way. Secondary light 409c, which serves as post-irradiation light reaching the light-receiving unit 20B, includes reflected light and scattered light from the observation object. It is known that reflected light contains polarized light components. This secondary light may also include secondary light (scattered light and fluorescent light) obtained when the white light 409 penetrates into the observation object, particularly the material of the sheath 3, and interferes with the material therein.

[0105] An observation test was conducted using the specifications of each component of the observation device H described above, except for the near-infrared light source. The white light source was a point light source, irradiated from above the object of observation at an approximately 45-degree angle without any polarizing plate. The light-receiving unit 120B was also positioned above the object of observation. A circulating fluid 6 containing a secondary light-emitting material that receives the irradiated light and emits secondary light is placed around the sheath 3. This secondary light preferably serves as auxiliary light, creating a lantern effect on the sheath 3. The observation results are shown in Figure 15. Figure 16 shows an image obtained when the second polarizing plate 124B was removed from the observation device. The catheter insertion state into the vascular model is the same as in Figure 15.

[0106] The image generating assembly of observation device B, the image generating assembly of observation device C, and the image generating assembly of observation device D can also be applied to other observation devices.

[0107] Figure 17 shows an observation device I of another embodiment. In Figure 17, the same elements as in Figure 2 are assigned the same reference numerals, and their description will be omitted. In this observation device I, two observation assemblies are arranged so as to be perpendicular to the observation target assembly 101. The observation assembly includes a light-emitting unit composed of a near-infrared light source 122 and a first polarizing plate (not shown), and a light-receiving unit composed of a second polarizing plate 124 and an infrared camera 125. In this observation assembly, the light-receiving unit can be moved horizontally.

[0108] The second observation assembly includes a second light-emitting unit consisting of a near-infrared light source 1122 and a first polarizing plate (not shown), and a second light-receiving unit consisting of a second polarizing plate 1124 and an infrared camera 1125. This second observation assembly can move the second light-receiving unit vertically. By moving the two observation assemblies in synchronization, a first portion of the observation object can be observed from two axial directions. By displaying images based on the observation output of each observation assembly side by side, biplane observation can be simulated. Either or both of the near-infrared light sources of each light-emitting unit can be replaced with a white light source. The two light sources can be shared, and light from this can be emitted from the bottom and side of the case of the observation object assembly via a predetermined optical transmission member.

[0109] The present invention is not limited to the above-described embodiments and examples, and various modifications within the scope of the claims and within the scope that can be easily conceived by a person skilled in the art are also included in the present invention.

[0110] The above has described an observation device that uses polarized light. The following points are examples of new findings that can be applied to conventional observation devices that do not use polarized light and that improve their performance. The basic principle of the X-ray-free conventional observation device disclosed in Prior Art Document 1 is the discovery that near-infrared light passes through the catheter sheath when the object of observation is irradiated with near-infrared light. As a result, in the captured image, the catheter wire, which blocks near-infrared light, appears black, while the sheath appears relatively white (gray) due to the near-infrared light that has passed through it. In this way, the sheath and wire can be distinguished by their difference in brightness, even in conventional types of observation devices.

[0111] In the above-mentioned conventional example, no polarized light was used, and the basic irradiation light emitted from the light-emitting unit was transmitted through the object of observation, and the post-irradiation light obtained by the transmission was observed by the light-receiving unit. As can be understood from the above explanation, the post-irradiation light received by the light-receiving unit can also be reflected light or secondary light from the object of observation.

[0112] Therefore, we propose a novel observation device having the following configuration: (1) An observation device for observing a blood vessel model into which a catheter has been inserted, comprising a light receiving unit for post-illumination light, wherein the post-illumination light is reference illumination light that has been irradiated onto the observation object and has been subjected to interference from the observation object, wherein the light receiving unit is disposed at a second position where it can mainly receive post-illumination light formed when the reference illumination light is reflected from the observation object, and / or a third position where it can mainly receive secondary light generated when the reference illumination light interferes with the observation object.

[0113] (2) An observation device for observing a blood vessel model into which a catheter has been inserted, comprising: an observation assembly having a light-emitting unit and a light-receiving unit; and an image generation assembly having an image generation unit and a display, wherein the light-emitting unit irradiates reference illumination light toward the observation object, the light-receiving unit receives post-illumination light and outputs an observation output, the post-illumination light being light generated by the reference illumination interfering with the observation object and including a light component originating from a catheter sheath, the image generation unit generates an image according to the observation output, and the display displays the image, wherein the observation assembly is capable of observing a first region of the observation object and a second region different from the first region.

[0114] (3) An observation device for observing a blood vessel model into which a catheter has been inserted, comprising: an observation assembly having a light-emitting unit and a light-receiving unit; and an image generation assembly having an image generation unit and a display, wherein the light-emitting unit irradiates reference illumination light toward the observation object; the light-receiving unit receives post-illumination light and outputs an observation output, the post-illumination light being light generated by the reference illumination interfering with the observation object and including a light component originating from the catheter sheath; the image generation unit generates an image according to the observation output; and the display displays the image, the observation device further comprising a second observation assembly including a second light-emitting unit and a second light-receiving unit, and the second observation assembly observes the part of the observation object observed by the observation assembly from another direction.

[0115] (4) The observation device according to (3), wherein the observation assembly and the second observation assembly are movable relative to the observation target.

[0116] (5) The observation device according to (3), wherein the output unit and the second output unit have a common light source.

[0117] (6) An observation device for observing a blood vessel model into which a catheter has been inserted, comprising: an observation assembly having a light-emitting unit and a light-receiving unit; and an image generation assembly having an image generation unit and a display, wherein the light-emitting unit irradiates reference irradiation light toward the observation object; the light-receiving unit receives post-irradiation light and outputs an observation output, the post-irradiation light being light generated by the reference irradiation light interfering with the observation object and including a light component originating from the catheter sheath; the image generation unit generates an image according to the observation output; and the display displays the image; wherein, when the light-emitting unit irradiates reference irradiation light of a first wavelength, the light-receiving unit generates a 1-2 image; and when the light-emitting unit irradiates reference irradiation light of a second wavelength, the light-receiving unit generates a 1-3 image; the image generation unit generates a composite image of the 1-2 image and the 1-3 image; and the display displays the composite image.

[0118] (7) The observation device according to (6), wherein the first-second image displays only the sheath of the catheter and the metal linear body within the sheath, and the first-third image displays the blood vessel model.

[0119] (8) The observation device according to (7), wherein the first-second image is a moving image.

[0120] REFERENCE SIGNS LIST 1, 101 Observation object assembly 2 Catheter 3 Sheath 4 Wire 5, 105 Blood vessel model 6 Circulating fluid 7 Immersion fluid 9 Near-infrared light 20, 120, 220, 320, 420 Observation assembly 22, 122 Near-infrared light source 23, 123 First polarizing plate 24, 124 Second polarizing plate 25, 125 Near-infrared camera 30, 130, 230, 330 Image generation assembly 31 Image generation unit 33 Display 109 White light 122A White light source 125A Visible light camera A to I Observation device

Claims

1. An observation device for observing a blood vessel model with an inserted catheter, the observation device comprising a light receiving unit, the light receiving unit having predetermined polarization characteristics, receiving and imaging a polarized component of post-illumination light that matches the predetermined polarization characteristics, wherein the post-illumination light is reference illumination light that is irradiated onto the observation object and has been subjected to interference from the observation object, and includes a polarized component that is imaged by the light receiving unit, the polarized component originating from the sheath of the catheter.

2. An observation device as described in claim 1, further comprising a light-emitting unit and an image display assembly, wherein the light-receiving unit and the light-emitting unit constitute an observation assembly, the light-emitting unit irradiates the reference illumination light toward the object to be observed, the reference illumination light including a first polarization, the light-receiving unit receiving the post-illumination light generates an observation output according to the polarization component to be imaged, and the image display assembly comprises an image generation unit and a display, the image generation unit generates an image based on the observation output, and the display displays the image.

3. An observation device as described in claim 2, wherein the image generating unit generates an image based on a comparison between the reference output from the light receiving unit that receives the reference irradiation light that does not interfere with the object of observation and the observation output.

4. The observation device described in claim 3, wherein the reference output is the output when the light receiver with the polarization characteristic removed receives the reference illumination light that does not interfere with the object of observation, the light receiving unit has a polarization axis in a direction different from the first direction as the polarization characteristic, and the light receiving unit generates an observation output corresponding to the polarization component imaged by the light receiving unit.

5. The observation device described in claim 3, wherein the reference output is the output of the light receiving unit that receives the reference illumination light that does not interfere with the object of observation as the post-illumination light, and the light receiving unit generates an observation output corresponding to the polarization direction component of the polarized light contained in the received post-illumination light.

6. An observation device as described in claim 1, comprising an observation object assembly including the observation object, a circulating fluid circulating through the blood vessel model, and an immersion fluid in which the observation object is immersed, wherein at least one selected from the constituent materials of the blood vessel model, the immersion fluid, and the circulating fluid is dispersed with a secondary light generating material that interferes with the reference illumination light to generate secondary light, and the secondary light interferes with at least the sheath to emphasize the polarization component originating from the sheath in the post-illumination light.

7. An observation device according to claim 6, wherein the secondary light generating material dispersed in the immersion liquid and the circulating liquid causes Rayleigh scattering of the reference illumination light.

8. An observation device according to claim 7, wherein the secondary light generating material that causes Rayleigh scattering is a water-soluble polymer and / or a surfactant.

9. An observation device according to claim 2, wherein the immersion liquid and / or the circulating liquid have light absorption characteristics and / or polarization characteristics for the reference irradiation light that are different from those of the blood vessel model.

10. An observation device according to claim 2, wherein the material forming the blood vessel model produces a photoelastic effect on the reference irradiation light, and the light produced by the photoelastic effect is included in the post-irradiation light.

11. The observation device according to claim 2, wherein the observation target assembly further comprises a plate for holding the blood vessel model, the plate transmits the reference illumination light, the plate has a groove that follows the shape of the blood vessel model, and the blood vessel model is fitted into the groove completely or partially without any gaps.

12. An observation device according to claim 11, wherein the peripheral wall of the groove in the plate is formed of a soft material that produces a photoelastic effect for the reference irradiation light, and the light produced by the photoelastic effect is included in the post-irradiation light.

13. An observation device as described in claim 2, wherein the blood vessel model in the observation object assembly has a movable part simulating a thrombus or the like disposed inside the blood vessel model, and the movable part interferes with the reference illumination to modulate its polarization state.

14. The observation device according to claim 2, wherein the observation assembly is capable of photographing a first portion of the observation object and a second portion different from the first portion.

15. An observation device according to claim 14, further comprising a second observation assembly having a second light emitting section and a second light receiving section, the second observation assembly observing the portion of the object observed by the observation assembly from another direction.

16. The observation device according to claim 15, wherein the observation assembly and the second observation assembly are movable relative to the object to be observed.

17. The observation device described in claim 1, wherein the light receiving unit is arranged at one or more of the following positions: a first position capable of mainly receiving post-illumination light formed when the reference illumination light passes through the object of observation; a second position capable of mainly receiving post-illumination light formed when the reference illumination light is reflected by the object of observation; and a third position capable of mainly receiving secondary light generated when the reference illumination light interferes with the object of observation.

18. The observation device of claim 11, wherein the observation target assembly includes a case for holding the immersion liquid, the case forming part of a mannequin, and the plate being disposed within the case.

19. The observation device according to claim 2, wherein the observation target assembly includes a case for holding the immersion liquid, and the peripheral wall of the case includes the light-emitting portion.

20. The observation device according to claim 2, wherein the observation object assembly includes a case for holding the immersion liquid, and the case is provided with an anti-reflection section for the reference irradiation light on the side of the light emitting section.

21. An observation device as described in claim 20, wherein the object to be observed is biased toward the light receiving unit within the case, making the layer of immersion liquid between the object to be observed and the light emitting unit thicker than the layer of immersion liquid between the object to be observed and the light receiving unit, and causing the layer of immersion liquid between the object to be observed and the light emitting unit to perform the function of the anti-reflection unit.

22. An observation device according to claim 2, wherein a fluorescent material that emits a polarized component that is imaged by the light receiving unit is attached to a component of the observation object assembly, and the observation assembly is provided with a light source that causes the material to fluoresce.

23. The observation device according to claim 22, wherein the observation target assembly includes a case that holds the immersion liquid, the light is ultraviolet light, and the ultraviolet light from the light source is introduced into the case and emitted from a side wall of the case toward the observation target.

24. An observation device as described in claim 2, wherein the light receiving unit has a second polarization characteristic state and a third polarization characteristic state in directions relatively different from the first direction of the first polarization, the image display assembly has an image synthesis unit, which generates an observation output that generates a first-second image when the light receiving unit is in the second polarization characteristic state, and generates an observation output that generates a first-third image when the light receiving unit is in the third polarization characteristic state, the image synthesis unit synthesizes the first-second image and the first-third image, and the display displays the synthesized image.

25. An observation device according to claim 24, wherein the first-second image displays only the sheath of the catheter and the metal linear body within the sheath, and the first-third image displays the blood vessel model.

26. The observation device according to claim 25, wherein the first and second screens are moving images.

27. An observation method using an observation device in which a blood vessel model into which a catheter has been inserted is observed as an observation object, the observation method comprising the steps of: irradiating the observation object with reference illumination light; receiving post-illumination light generated by the reference illumination light that has been interfered with by the observation object, the post-illumination light including a polarized component that originates from a sheath of the catheter; and generating an output based on the polarized component that matches the polarization characteristics of the polarized component originating from the sheath and is imaged by the light-receiving unit.

28. An observation method as described in claim 27, wherein a secondary light generating material that interferes with the reference illumination light to generate secondary light is dispersed in at least one selected from the constituent materials of the blood vessel model, the lubricating liquid circulating within the blood vessel model, and the immersion liquid in which the blood vessel model is immersed, and the polarization component of the post-illumination light is changed by causing the secondary light to interfere with the sheath.

29. An observation method according to claim 27, wherein the polarizing unit has a second polarization characteristic state and a third polarization characteristic state in a direction relatively different from the first direction of the first polarization, and the contrast between the catheter sheath and its surroundings in the displayed image is adjusted by adjusting the second polarization characteristic state and the third polarization characteristic state.

30. An observation method as described in claim 29, comprising the steps of: generating a contrast mode image in which only the sheath of the catheter and the metal linear object within the sheath are displayed in the second polarized light receiving state; obtaining a still mode image in which a blood vessel model is displayed in the third polarized light receiving state; and displaying the still mode image and the contrast mode image in an overlapping manner.

31. A cassette incorporating a blood vessel model, used in an observation device that irradiates the observation object with reference irradiation light that interferes with the sheath of a catheter, the cassette comprising: the blood vessel model; a housing that holds the blood vessel model; and a polarizing element that is arranged between the blood vessel model and the light source.

32. A plate for holding a catheter in an observation device for observing a blood vessel model with a catheter inserted therein, the plate having a groove that follows the shape of the blood vessel model, and the peripheral wall of the groove contacts the blood vessel model entirely or partially without any gaps.

33. The plate according to claim 32, wherein the peripheral wall of the groove is formed of a soft material that produces a photoelastic effect.

34. An observation device for observing a blood vessel model into which a catheter has been inserted, comprising: an observation assembly including a light-emitting unit and a light-receiving unit; and an image display assembly including an image generating unit and a display; wherein the light-emitting unit has a light source and a polarizing element and irradiates reference illumination light including a first polarized light toward the observation object; the polarizing element has a polarization axis in a first direction and transmits the first polarized light polarized in the first direction out of the light output from the light source; the first polarized light passes through the sheath of the catheter, and the polarization state of at least some of the light components is modulated; the light-receiving unit has a light receiver and an analyzer, and the analyzer has a polarization axis in a second direction different from the first direction; the light receiver receives the light component that has passed through the analyzer out of the reference illumination light (post-irradiation light) that has been irradiated to the observation object and has experienced interference from the observation object, and generates an observation output; the image generating unit receives the observation output and generates an image; and the display displays the image.

Images