JP2008070847A - Catheter operation simulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce a fluoroscopic operation picture in a catheter operation in a three-dimensional model which reproduces a body cavity such as a blood vessel. <P>SOLUTION: A three-dimensional model is dipped in a light-permeable liquid adjacent to the three-dimensional model to make the peripheral shape and cavity shape of the three-dimensional model substantially invisible. Then, the image of this condition is picked up to reproduce a fluoroscopic picture at the time of an operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a catheter surgery simulator.

Technical background

The present inventors have proposed a block-shaped three-dimensional model that reproduces a body cavity such as a blood vessel of a subject (Patent Document 1, Non-Patent Document 1). This three-dimensional model is formed by layering a body cavity model such as a blood vessel based on tomographic image data of the subject, surrounding the body cavity model with a three-dimensional model molding material, curing the three-dimensional model molding material, and then removing the body cavity model Can be obtained.
By adopting an elastomeric material such as silicone rubber as the 3D model molding material, the liquid moves into the 3D model cavity (reproduced blood vessels) and the movement of the 3D model when the catheter is inserted. Can be observed.
Also, a film-like three-dimensional model (Non-Patent Document 2) is proposed.
Moreover, the solid model comprised with the gel-like base material is proposed (nonpatent literature 3).

  WO 03/096308   A medical model for surgical trials reproducing the cerebral vascular lumen, Proceedings of the 20th Annual Conference of the Robotics Society of Japan, 2002   Research on surgical simulator based on biological information for intravascular surgery, Proceedings of Lecture Meeting on Robotics and Mechatronics, 2003   Three-dimensional model for surgical simulation that reproduces the lumen of the cerebral blood vessel.

  According to the above model, the dynamic deformation of the cavity portion that reproduces the body cavity can be directly observed visually with respect to the catheter and liquid insertion simulation. However, in actual surgery, catheters and liquids are inserted while confirming fluoroscopic images using X-rays or the like, so that the visual observation image is largely the same as the fluoroscopic image observed during the surgical simulation. Different.

The present invention has been made to solve the above problems, and is configured as follows.
A translucent liquid having a refractive index close to that of the three-dimensional model around the translucent three-dimensional model capable of inserting a catheter, at least around the cavity that reproduces the body cavity is formed of an elastic material. A perspective observation device that generates a fluoroscopic image similar to that at the time of an actual operation, by substantially satisfying the above, so that the external shape of the three-dimensional model is substantially invisible.
A translucent liquid with a refractive index close to the three-dimensional model;
A container for holding the translucent liquid;
An imaging device for imaging the three-dimensional model,
A catheter surgery simulator characterized in that a catheter or liquid inserted into the three-dimensional model can be viewed.

According to the perspective observation apparatus for a three-dimensional model configured in this way, the surrounding shape and cavity shape of the three-dimensional model can be substantially invisible in the catheter and liquid insertion simulation, and are used during actual surgery. An image similar to the fluoroscopic image can be generated. This enables a surgical simulation while observing a fluoroscopic image similar to that at the time of surgery.
In addition, the stress applied to the surrounding area of the three-dimensional model can be visualized using the photoelastic effect, and the stress information can be additionally displayed as an overlay on the above-mentioned fluoroscopic image. It is possible to construct an environment that can be evaluated from the stress side.

Here, a mixed liquid of glycerin and water can be used as the liquid that fills the periphery of the three-dimensional model, the cavity region, or both. This liquid mixture has viscosity close to that of body fluids (especially blood), high translucency, and is harmless to the living body. It is possible to reproduce more realistically and observe clearly and safely.
In addition, when applying a material with a high refractive index (refractive index of about 1.5 or more) as a constituent material of the three-dimensional model, a mixture of α monobromonaphthalene and liquid paraffin is used to refract the three-dimensional model. It is also possible to produce liquids close to the rate.

Hereinafter, each component of the invention will be described in detail.
(3D model forming material)
In order to observe the state of the catheter and the liquid inserted in the cavity region of the three-dimensional model, at least a portion that requires internal observation is formed of a translucent material in the three-dimensional model.
Examples of such translucent materials include silicone rubber (silicone elastomer), thermosetting polyurethane elastomer and other elastomers, silicone hydrogel, PVA hydrogel, gelatin and other gels, silicone resin, epoxy resin, polyurethane, Thermosetting resins such as unsaturated polyesters, phenol resins and urea resins, and thermoplastic resins such as polymethyl methacrylate can be used alone or in combination.
When a catheter or liquid is inserted into a cavity of a three-dimensional model, in order to reproduce the deformation of the cavity area that reproduces the body cavity, at least the surrounding area needs to be formed of an elastically deformable material. An example of such a material is gelatin (animal fertilizer). In addition, polysaccharide gelling agents such as vegetable epilepsy, carrageenan and locust bean gum can also be employed.

(Method for forming a solid model)
In the three-dimensional model, the cavity can be a reproduction of a body cavity such as a blood vessel formed based on the tomographic image data of the subject.
Here, the subject is the whole or part of the human body, but animals and plants can be the target of tomographic imaging. It does not exclude corpses.
The tomographic image data refers to data that is the basis for executing additive manufacturing. In general, three-dimensional shape data is constructed from tomographic image data obtained by an X-ray CT apparatus, an MRI apparatus, an ultrasonic apparatus, etc., and the three-dimensional shape data is decomposed into two-dimensional data to obtain tomographic image data.
Hereinafter, an example of tomographic image data generation will be described.

  Here, a case will be described in which a plurality of two-dimensional images obtained by imaging at equal intervals while being translated in the body axis direction are used as input data (tomographic imaging data). Even when a two-dimensional image or a three-dimensional image is used as an input image, three-dimensional shape data of the cavity can be obtained by performing the same processing. Each input two-dimensional image is first accurately laminated based on the imaging interval at the time of imaging. Next, by specifying a threshold for the image density value on each two-dimensional image, only the cavity region that is the target of the body cavity model is extracted from each two-dimensional image, while other regions are stacked. Delete from the two-dimensional image. As a result, the three-dimensional shape of the portion corresponding to the cavity region is given in the form of a stack of two-dimensional images, and the contour line of each two-dimensional image is interpolated three-dimensionally and reconstructed as a three-dimensional curved surface. Three-dimensional shape data of the target cavity is generated. In this case, the cavity region is first extracted from the input image by designating a threshold value for the density value, but separately from this method, by specifying a specific density value that gives the cavity surface. It is also possible to directly generate a three-dimensional curved surface by extracting the cavity surface from the input image and performing three-dimensional interpolation. Further, the input images may be stacked after performing region extraction by specifying a threshold value (or surface extraction by specifying a specific density value). The generation of the three-dimensional curved surface may be performed by polygon approximation.

  The three-dimensional shape data can be modified or changed during or after the generation of the three-dimensional shape data. For example, adding a structure that does not exist in the tomographic data, adding a support structure called a support, removing a part of the structure in the tomographic data, or changing the shape of the cavity Thus, the shape of the cavity formed inside the three-dimensional model can be freely modified or changed. Furthermore, it is also possible to provide a non-layered modeling region inside the cavity, and in the case where a body cavity model having a non-layered modeling region provided with a non-layered modeling region is explained, Three-dimensional shape data in which the layered modeling region is provided inside the cavity is generated. In addition, you may perform these processes in the additive manufacturing system or the software corresponding to an additive manufacturing system.

Next, the generated three-dimensional shape data of the cavity is converted into a format corresponding to the additive manufacturing system used for the additive manufacturing of the body cavity model as necessary, and used for the additive manufacturing system or the additive manufacturing system to be used. Send to compatible software.
The additive manufacturing system (or software that supports additive manufacturing systems) supports the setting of various setting items such as the placement of the body cavity model and the stacking direction during additive manufacturing as well as the purpose of maintaining the shape during additive manufacturing. (Support structure) is added to the place where support is required (if it is not necessary, it is not necessary to add it). Finally, slice data (tomographic image data) that is directly used for additive manufacturing is generated by slicing the modeling data obtained in this way based on the modeling thickness at the time of additive manufacturing. In contrast to the above procedure, support may be added after slice data is generated. Moreover, when the slice data is automatically generated by the additive manufacturing system (or software corresponding to the additive manufacturing system) used, this procedure can be omitted. However, even in this case, the layered modeling thickness may be set. The same applies to the addition of the support. When the support is automatically generated by the additive manufacturing system (or software corresponding to the additive manufacturing system), it is not necessary to generate the support manually (may be generated manually). ).

  In the above example, 3D shape data is constructed from tomographic imaging data. However, when 3D shape data is given from the beginning as a data, it is decomposed into 2D and used in the next additive manufacturing process. Image data can be obtained.

  In this invention, a body cavity such as a blood vessel is targeted, and the body cavity is a cavity located in various organs (skeletal, muscle, circulatory, respiratory, digestive, urogenital, endocrine, nerve, sensory organs, etc.) And a cavity formed by a geometric arrangement of these organs and body walls. Therefore, the lumens of organs such as heart lumen, stomach lumen, intestinal lumen, uterine lumen, blood vessel lumen, ureter lumen, oral cavity, nasal cavity, strait, middle ear A cavity, a body cavity, a joint cavity, a pericardial cavity, and the like are included in the “body cavity”.

The body cavity model is formed from the tomographic image data.
Although the formation method is not particularly limited, layered modeling is preferable. Here, the layered structure means that a thin layer is formed based on the tomographic image data, and this is sequentially repeated to obtain a desired shape.
The layered body cavity model must be decomposed and removed in a later process. In order to facilitate the removal, it is preferable that the material used for additive manufacturing is a material having a low melting point or a material that is easily dissolved in a solvent. As such a material, a low-melting-point thermosetting resin or wax can be used. A photo-curable resin widely used in so-called stereolithography (included in layered modeling) can be used if it can be easily decomposed.

If the body cavity model has a strength that can withstand external forces such as pressure applied from the outside when surrounded by the three-dimensional model molding material in the next step, the inside can be thinned with a hollow structure. . This not only reduces the time required for layered modeling and the cost associated with modeling, but also simplifies elution of the body cavity model in the subsequent elution process.
Specific examples of the additive manufacturing method include a powder sintering method, a molten resin ejection method, a molten resin extrusion method, and the like.

The body cavity model created by additive manufacturing can be subjected to various processes (removal processing and additional processing) such as surface polishing and surface coating after additive manufacturing, which allows the body cavity model to be It is possible to modify or change the shape. As a part of these processes, when a support that needs to be removed after the layered modeling is added in the production of the body cavity model, the support is removed.
By coating the surface of the body cavity model with another material, it is possible to prevent some or all components of the body cavity model material from diffusing into the three-dimensional model molding material. In addition, the diffusion can be prevented by physically treating the surface of the body cavity model (heat treatment, high frequency treatment, etc.) or chemically treating the surface.

  It is preferable to smooth the level difference on the surface of the body cavity model by surface treatment. As a result, the lumen surface of the three-dimensional model becomes smooth, and the actual body cavity inner surface such as a blood vessel can be reproduced. Examples of the surface treatment include contacting the surface of the body cavity model with a solvent, heating to melt the surface, coating, and using these in combination.

  A part or the whole of the body cavity model is surrounded with a three-dimensional model molding material and cured. A three-dimensional model is formed by removing the body cavity model.

(Other 3D models)
The three-dimensional model can also have a multilayer structure. That is,
A three-dimensional model is formed from a membranous model having a cavity in which a body cavity such as a blood vessel is reproduced and a base material surrounding the membranous model.
In the three-dimensional model configured as described above, the membrane structure of the biological blood vessel and the structure of the soft tissue around the blood vessel are individually reproduced including physical characteristics. Thereby, the model of the blood vessel having a membranous structure having flexibility is embedded in the base material having the viscoelastic characteristics of the tissue around the blood vessel. For this reason, in a medical instrument or fluid insertion simulation, a blood vessel model having a film-like structure inside a three-dimensional model can be flexibly deformed in the same manner as a blood vessel in a living body, and the deformation characteristics of a living blood vessel are reproduced. It becomes a suitable thing.
Here, the membranous model is obtained by thinly laminating a membranous model molding material on the surface of the body cavity model described above and curing it.
The molding material of the membranous model is not particularly limited as long as it is an isotropic material exhibiting a photoelastic effect. For example, in addition to elastomers such as silicone rubber (silicone elastomer) and thermosetting polyurethane elastomer, silicone resin, epoxy resin , Use of thermosetting resins such as polyurethane, unsaturated polyester, phenolic resin, urea resin, thermoplastic resins such as polymethyl methacrylate, gels such as silicone hydrogel and PVA hydrogel, alone or in combination can do. These materials are thinly laminated on the surface of the body cavity model by a method such as application, spraying, or dipping, and then vulcanized or cured by a known method.
When the target of the membranous model is a cerebral blood vessel model, it is preferable to employ a material that is translucent and has elasticity and flexibility close to living tissue. An example of such a material is silicone rubber. In addition, since silicone rubber has contact characteristics equivalent to those of living tissue, a medical instrument such as a catheter is inserted to be suitable for a trial of surgery.
The membranous model forming material can be formed from a plurality of layers. The thickness can also be set arbitrarily.

The base material is preferably a translucent material having physical properties similar to those of living tissue.
Here, the biological tissue is a flexible tissue surrounding a blood vessel or the like reproduced by the membranous model. In the examples, silicone gel and glycerin gel were used as materials for reproducing such flexibility (physical properties). Gelatin, orange, polysaccharide gel and the like can also be used. In addition, if a casing can ensure airtightness, a highly viscous liquid can also be used as a base material.
When gel is used as the material of the base material, the base material can be brought closer to a living tissue by using a plurality of materials having different physical properties.
In order to observe the dynamic behavior of the membranous model, the base material is preferably translucent. In order to clarify the boundary between the membranous model and the substrate, at least one of the membranous model and the substrate can be colored. Further, it is preferable that the refractive index of the material of the film model and the refractive index of the material of the base material are substantially equal so that the dynamic behavior of the film model can be observed more accurately.
The entire membranous model need not be embedded in the substrate. That is, a part of the membranous model may be located in the gap (see FIG. 3). Also, a part of the membranous model may be in a solid substrate (having dissimilar physical characteristics to living tissue).
A base material shall have elasticity. Preferably, the elastic modulus is low elasticity of 2.0 kPa to 100 kPa. More preferably, the substrate has sufficient elongation. Thereby, even if a membranous model changes greatly, a substrate does not peel from a membranous model. For example, when no load is set to 1, it is preferable that the substrate has an elongation ratio of 2 to 15 times that when no addition is applied when the substrate is pulled in a state in which adhesion to the film model is ensured. Here, the elongation percentage refers to the maximum amount of deformation that the base material can return to. In addition, it is preferable that the speed at which the base material is restored when the load is removed from the base material deformed by applying a load is relatively moderate. For example, the loss coefficient tan δ (at 1 Hz), which is a viscoelastic parameter, can be set to 0.2 to 2.0.
As a result, the base material has characteristics similar to or close to those of the tissue existing around the blood vessel or the like, and the deformation of the membranous model is performed in an environment that is closer to reality. That is, the insertion feeling of a catheter or the like can be realistically reproduced.
A base material shall have adhesiveness with respect to a membranous model. Thereby, even if a catheter or the like is inserted into the membranous model and the membranous model is deformed, no deviation occurs between the base material and the membranous model. If there is a difference between the two, the stress applied to the membranous model will change, which may hinder, for example, a catheter insertion simulation, and may cause discomfort during the insertion.
When a cerebrovascular model is used as the membranous model, the adhesion (adhesion strength) between the substrate and the membranous model is preferably 1 kPa to 20 kPa.
In this embodiment, silicone gel and glycerin gel are used as the base material, but the material is not particularly limited. In addition, if a casing can ensure airtightness, a highly viscous liquid can also be used as a base material. This is particularly suitable as a base material for a membranous model that reproduces a blood vessel surrounded by a living tissue having no elasticity. A suitable base material can also be prepared by mixing these plural kinds of fluids and further mixing an adhesive agent thereto.
When gel is used as the material of the base material, the base material can be brought closer to a living tissue by using a plurality of materials having different physical properties.
In order to observe the dynamic behavior of the membranous model, the base material is preferably translucent. In order to clarify the boundary between the membranous model and the substrate, at least one of the membranous model and the substrate can be colored. Further, it is preferable that the refractive index of the material of the film model and the refractive index of the material of the base material are substantially equal so that the dynamic behavior of the film model can be observed more accurately.
The entire membranous model need not be embedded in the substrate. That is, a part of the membranous model may be located in the gap (see FIG. 4). Further, a part of the membranous model may be in a solid substrate (having dissimilar physical properties to living tissue) or in a fluid.

A casing accommodates a base material and can take arbitrary shapes. The whole or a part thereof is formed of a translucent material so that the dynamic behavior of the membranous model can be observed. Such a casing can be formed of a light-transmitting synthetic resin (such as an acrylic plate) or a glass plate.
The casing has a hole communicating with the cavity of the membranous model. A catheter can be inserted through this hole.
The three-dimensional model is preferably translucent as a whole. From the viewpoint of observing the insertion state of the catheter, it is sufficient that at least the inside of the membranous model can be visually recognized.
Provide a sufficient distance between the casing and the membranous model. As a result, a sufficient margin (thickness) is secured for the elastic base material, and when an external force is applied to the membranous model by insertion of a catheter or the like, the membranous model can be freely deformed according to the external force. This margin can be arbitrarily selected according to the object, application, etc. of the three-dimensional model, but is preferably set to 10 to 100 times or more the film thickness of the membranous model, for example.

The core in a state where the body cavity model is covered with the membranous model is set in the casing, and the base material is injected into the casing for gelation.
Thereafter, when the body cavity model is removed, the membranous model remains in the base material.
The method of removing the body cavity model is appropriately selected according to the modeling material of the body cavity model, and is not particularly limited as long as other materials of the three-dimensional model are not affected.
As a method for removing the body cavity model, (a) a heat melting method that melts by heating, (b) a solvent dissolution method that dissolves by a solvent, (c) a hybrid method that combines melting by heating and dissolution by a solvent, etc. are adopted. be able to. By these methods, the body cavity model is selectively fluidized and eluted out of the three-dimensional model to remove it.

  Some of the components of the material of the body cavity model may diffuse into the membranous model, causing the membranous model to become cloudy, and the visibility thereof may be reduced. In order to remove this fogging, it is preferable to reheat the sample after removing the body cavity model. This heating can also be performed during the removal of the body cavity model.

A three-dimensional model can also be formed as follows.
The body cavity model is embedded as a core in a gel-like base material, and the body cavity model is removed. Thereby, the cavity which reproduced the body cavity in the base material is formed. Thereafter, a film-form model forming material is attached to the peripheral wall of the cavity and cured by polymerization or vulcanization. By flowing the membranous model forming material into the cavity of the base material, or by dipping the base material into the membranous model forming material, the membranous model forming material can be attached to the peripheral wall of the body cavity of the base material.

Further, the peripheral wall of the cavity can be hydrophilized instead of attaching the membranous model forming material to the peripheral wall of the cavity. Thereby, when water or an aqueous solution is filled in the cavity of the three-dimensional model, a water film is formed on the peripheral wall, and the insertion resistance of the catheter is alleviated. That is, this water film corresponds to the membranous model.
Similarly, when the peripheral wall of the cavity is subjected to a hydrophobic treatment (lipophilic treatment), when the cavity is filled with oil, an oil film is formed on the peripheral wall and the insertion resistance of the catheter is reduced. That is, this oil film corresponds to a film model.

  The peripheral wall of the cavity is made hydrophilic or hydrophobic by a known method. For example, when silicone gel is employed as the substrate, the peripheral wall of the cavity can be hydrophilized by forming a film having a polar group such as a surfactant on the peripheral wall. Similarly, the peripheral wall of the cavity can be hydrophobized by forming an oily film such as oil or wax on the peripheral wall of the cavity.

  The body cavity model base can be formed of a light-transmitting gel material such as silicone rubber, and the peripheral wall of the body cavity can be entirely or partially covered with a material having a photoelastic coefficient higher than that of the gel material. A material having a high photoelastic coefficient can also be embedded in the base material. The photoelastic effect is emphasized by the material having a high photoelastic coefficient. In addition, an epoxy resin etc. can be mentioned as a material with a high photoelastic coefficient. Since the epoxy resin thin film is easily deformed by insertion of the catheter, the photoelastic effect can be clearly observed by using this.

A casing accommodates a base material and can take arbitrary shapes. The whole or a part thereof is formed of a translucent material so that the dynamic behavior of the membranous model can be observed. Such a casing can be formed of a light-transmitting synthetic resin (such as an acrylic plate) or a glass plate.
The casing has a hole communicating with the cavity of the membranous model. A catheter can be inserted through this hole.
The three-dimensional model is preferably translucent as a whole. From the viewpoint of observing the insertion state of the catheter, it is sufficient that at least the inside of the membranous model can be visually recognized.

(Fluoroscopic imaging)
In surgical procedures such as catheter endovascular treatment, the inside of the body is imaged in real time by fluoroscopically imaging the surgical region by X-ray irradiation, etc., thereby allowing catheters and fluids to enter the body cavity while observing the surgical field. Insert and treat. In fluoroscopic imaging, three-dimensional body structures such as bones, organs, and body cavities are presented to the operator as two-dimensional monochrome images (video), so the three-dimensional shape and size of the operative field area can be directly known. I can't.
Performing surgery while confirming such a fluoroscopic image is a major feature of catheter surgery, which is one of minimally invasive surgery. In other words, unlike surgical procedures that open the body, such as laparotomy or craniotomy, the affected area cannot be seen directly, and the affected area cannot be touched directly. For the practicing operator, great difficulty is involved in performing the treatment.
Therefore, when a surgical simulation is performed by inserting a catheter or liquid into the cavity of a three-dimensional model that is a component of the present invention, the three-dimensional model is directly observed visually, which is extremely important for the main operation. The reproduction of this part is lacking, and it is insufficient as a simulation environment.

The three-dimensional model of the present invention is made of a translucent material (excluding support structures and other incidental structures). Therefore, by preparing a translucent liquid having the same refractive index as the constituent material of the three-dimensional model and immersing the three-dimensional model in the translucent liquid, the surrounding shape and cavity shape of the three-dimensional model can be changed. Can be substantially invisible. An image in this state is picked up by an image pickup device and projected on a display device such as a display, whereby an image close to a fluoroscopic image at the time of surgery can be obtained.
As such a translucent liquid, a mixed liquid of water and glycerin, a mixed liquid of α-monobromonaphthalene and liquid paraffin, or the like can be used.

Here, in the actual body, the X-ray transmittance of body fluid (blood, etc.) existing inside the body cavity is often close to the X-ray transmittance of the tissue existing around the body cavity. It is not possible to image (visualize) the shape of the body cavity region only by performing it. On the other hand, in such an X-ray fluoroscopic image, a large number of non-interest regions other than the body cavity region, such as bones and organs, are imaged (visualized).
In this way, simply performing fluoroscopic imaging does not capture the body cavity region, which is the region of interest, and only an image in which only the non-interest region is imaged, that is, an image that is very difficult to see when performing surgery is obtained. In order to solve this problem, in catheter surgery, there are techniques for selectively and clearly imaging a body cavity region, for example, a differential imaging method (DSA method) and a road map method.
Therefore, by constructing a highly realistic surgical simulation environment compared to the case of visually observing a stereoscopic model by reproducing a fluoroscopic surgical image obtained by these imaging techniques using the stereoscopic model of the present invention. be able to.
Hereinafter, the contents of the present invention for reproducing these photographing techniques will be described in detail.

  The difference imaging method (DSA method) described above performs two fluoroscopic imaging before and after inserting a catheter or a contrast medium (a drug for visualizing a body cavity region) into the body cavity to obtain two fluoroscopic images, By performing a difference operation (subtraction operation) on each fluoroscopic image, a portion where the change between the two fluoroscopic images is matched, that is, a portion where the catheter is inserted or a portion where the contrast of the cavity is contrasted is selectively performed. It is a method of visualizing and imaging. As a result, non-interest regions such as bones and surrounding organs can be excluded from the image, and a catheter and body cavity region, which are regions of interest, can be selectively visualized and an image suitable for focusing on surgery can be generated.

In the present invention, this differential imaging method is reproduced by the following method.
That is, by filling all or part of the periphery of the three-dimensional model 1001 and the cavity region XX of the three-dimensional model with a light-transmitting liquid having the same refractive index as (or close to) the three-dimensional model, After making the surrounding shape of the three-dimensional model and the shape of the cavity region substantially invisible, an image in this state is acquired by the imaging device to obtain a first fluoroscopic image.
Next, a catheter or dye is inserted into the three-dimensional model, and the second fluoroscopic image is obtained by imaging again from the same viewpoint as the first fluoroscopic image by the imaging device.
Finally, by performing the difference calculation process on the first image and the second image obtained, only the region that has changed between the two images, that is, the region where the catheter or dye is inserted is selected. Visualization can be performed to remove other regions, and a difference image similar to that at the time of actual surgery can be obtained.
After that, as the catheter insertion simulation progresses, the second image is updated and the difference calculation process with the first image is executed in real time, so that only the region of interest, that is, the visualization region using the catheter or dye is selected. Visually visualized video (video instead of image) can be obtained. Such a video reproduces well the difference video (DSA image) obtained during actual surgery.

  On the other hand, the roadmap method instantly visualizes the shape of the body cavity region by injecting contrast medium, and displays the obtained image as an overlay on the subsequent surgical image, while confirming the position and shape of the body cavity region. This is a technique for performing catheter manipulation. Here, the fact that the contrast medium is injected only instantaneously is due to the side effect of the contrast medium. That is, it is based on the restriction that the contrast medium cannot be administered constantly during the operation.

In the present invention, this road map method is reproduced by the following method.
That is, as in the previous difference method, all or part of the periphery of the three-dimensional model 1002 and the cavity region of the three-dimensional model are transmitted with the same (or close) refractive index as the three-dimensional model. By filling with a liquid, the surrounding shape of the three-dimensional model and the shape of the cavity region are substantially invisible, and then an image in this state is acquired by the imaging device to obtain a first fluoroscopic image.
Next, after injecting a dye resembling a contrast medium into the cavity region of the three-dimensional model 1001, the image is taken from the same viewpoint as the first fluoroscopic image to obtain a second fluoroscopic image.
Then, by performing a difference calculation process between the first image and the second image obtained in this way, a region that has changed between the images, that is, a cavity region XX into which the dye has been injected is selected. A visually visualized third image is generated. This third image is converted into a monochrome gradation, and a road map image is generated by performing gradation inversion processing in some cases.
By displaying this road map image on a subsequent photographed image (surgical image) obtained by the imaging device, a road map image similar to that during actual surgery is obtained.
In order to reproduce the road map method more precisely, after obtaining the road map image by the above method, only the catheter is selectively visualized by performing the differential processing detailed in [0055]. The generated difference video is generated, and the road map image is overlaid on the video. As a result, a more realistic surgical image (road map image) can be obtained.

(Photoelastic effect)
The photoelastic effect means that when an internal stress occurs in a translucent material, it temporarily has birefringence, and the refractive index differs in the direction of the maximum principal stress and the minimum principal stress. It means to proceed in a divided manner. An interference fringe is generated by the phase difference between the two waves, and the state of the internal stress of the translucent material can be known by observing the interference fringe.
In order to generate this photoelastic effect, as shown in FIG. 1, light from a light source is polarized through a first polarizing plate (polarizing filter), and this linearly polarized light is passed through a three-dimensional model. If an internal stress is generated in the three-dimensional model, birefringence occurs according to the strength of the internal stress, and a maximum main stress (acosφsinωt) and a minimum main stress (acosφsin (ωt−A)) are generated. Since these lights have different speeds, a phase difference is generated, and interference fringes appear when observed through the second polarizing plate (polarizing filter). The polarization direction of the second polarizing plate is substantially perpendicular to the changing direction of the first polarizing plate.
As a method for observing the photoelastic effect generated in light transmitted through the three-dimensional model by interposing a three-dimensional model between a pair of polarizing plates, an orthogonal Nicol method, a parallel Nicol method, a sensitive color method, and the like are known. Further, as a method for detecting the photoelastic effect by interposing a pair of quarter-wave plates (quarter-wave filters) between the polarizing plate and the three-dimensional model, a circular polarization method, a senalmon method, and the like are known. Yes.

In this way, by using the photoelastic effect, it is possible to observe a change in stress in a region around the cavity when the catheter is inserted into the cavity of the three-dimensional model. However, since the catheter itself does not produce any photoelastic effect, its position and state cannot be observed together with the photoelastic effect accompanying the stress change in the surrounding region.
Therefore, in the present invention, the position and state of the catheter itself can be observed by interposing a phase shift filter in the first polarizing filter on the light source side and the second change filter on the observer side. In other words, by the presence of the phase shift filter, a part of the light transmitted through the first polarizing filter is transmitted through the second polarizing filter and constitutes background light. Here, when a catheter exists in the three-dimensional model, it appears as a shadow, and its position, state and operation are observed. That is, it becomes possible to simultaneously observe the catheter and the photoelastic effect generated by the catheter.

As the phase shift filter, a filter that shifts the light transmitted through the first polarizing filter by one wavelength or two wavelengths can be used. This is because the sensitivity of the photoelastic effect is improved.
In the present invention, a plurality of wavelength shift filters may be used as long as background light can be extracted from the second polarizing filter on the viewer side. Note that a quarter wave plate is used in the circular polarization method, the senalmon method, etc., but since the background light cannot be extracted from the second change filter in these methods, the observation of the catheter is impossible. It is.

The photoelastic effect observed by the above method is overlaid and displayed on a pseudo fluoroscopic reproduction image obtained by the method described in detail in [0054] and thereafter, so that a fluoroscopic image in accordance with an actual operation is further added to the catheter. Stress information around the three-dimensional model at the time of insertion can be given. As a result, it is possible to construct an effective surgical simulation environment in which a catheter insertion simulation is performed while confirming a realistic fluoroscopic image and the simulation process can be evaluated from the stress side.
When the stress applied to the peripheral wall of the body cavity exceeds a certain value during the operation, the tissue is damaged. According to the present invention, the operator can intuitively grasp the surgical simulation in real time while confirming the strength of the stress applied to the three-dimensional model, so that it is possible to effectively learn the intraoperative risk. It becomes.

(First embodiment)
In order to obtain three-dimensional data related to the shape of the cerebral blood vessel to be a three-dimensional model and the cerebral artery that is the affected part, 0.35 × Imaging was performed with a helical scan X-ray CT apparatus having a spatial resolution of 0.35 × 0.5 mm. Three-dimensional data obtained by imaging is transferred to three-dimensional CAD software, so that two-dimensional images of 256 gradations having a resolution of 512 × 512 are arranged at equal intervals in the body axis direction (tomographic imaging). Then, the image data corresponding to each two-dimensional image was stored in a 5.25 inch magneto-optical disk by a drive built in the X-ray CT apparatus in the order corresponding to the imaging direction.

Next, the 5.25 inch magneto-optical drive externally connected to the personal computer is used to capture the image data into a storage device inside the computer, and from this image data, it is necessary for additive manufacturing using commercially available 3D CAD software. 3D shape data in the STL format (a format in which a 3D curved surface is expressed as an aggregate of triangular patches) is generated. In this conversion, the input two-dimensional image is layered based on the imaging interval to construct a three-dimensional scalar field with the density value as a scalar quantity, and a specific density that gives the blood vessel surface on the scalar field By specifying a value, after constructing the three-dimensional shape data of the blood vessel lumen as an isosurface (boundary surface of a specific scalar value), rendering of the triangular polygon approximation is performed on the constructed isosurface.
At this stage, additional data is added to the three-dimensional shape data, and the guide portion 13 is bulged from the end of the body cavity model 22 (see FIG. 2) (see FIG. 3). The guide portion 13 is a hollow columnar member. By providing the hollow portion 31, the layered modeling time is shortened. The distal end of the guide portion 13 has an enlarged diameter, and this portion is exposed on the surface of the three-dimensional model to form a large-diameter opening 15 (see FIG. 1).

The generated three-dimensional shape data in STL format is then transferred to a molten resin injection type additive manufacturing system to determine the model placement, stacking direction, and stacking thickness in the modeling system, and support the model at the same time. Was added.
A lot of slice data was generated by slicing the layered modeling data generated in this way to a predetermined layered modeling thickness (13 μm) on a computer. And based on each slice data obtained in this way, a modeling material (melting point: about 100 degrees, easily dissolved in acetone) mainly composed of p-toluenesulfonamide and p-ethylbenzenesulfonamide is heated. Laminated modeling was performed by laminating and forming one layer of a cured resin layer with a specified thickness having a shape that matches each slice data by being melted and ejected. By removing the support after the final layer was formed, a layered modeling model (body cavity model 22) of the cerebral vascular lumen region was created.
Further, the surface of the body cavity model 22 is processed to be smooth.

A silicone rubber layer 12 was formed to a thickness of approximately 1 mm on the entire surface of the body cavity model 12 (see FIG. 1). This silicone rubber layer 12 is obtained by dipping the body cavity model 22 into a silicone rubber tank and drying it while rotating the body cavity model. This silicone rubber layer becomes a membranous model.
In this embodiment, the entire surface of the body cavity model 22 is covered with the silicone rubber layer 12, but a desired part of the body cavity model 22 may be partially covered with the silicone rubber layer 12.

A core formed by coating the body cavity model with a film model made of a silicone rubber layer is set in a rectangular parallelepiped casing. This casing is made of a translucent acrylic plate. The base material is injected into the casing and gelled.
A two-component mixed silicone gel was used as a material for the substrate. This silicone gel has translucency and elasticity, and has physical properties very close to the soft tissue around the blood vessel. A condensation polymerization type silicone gel can also be used. Thus, a base material shall be provided with translucency and elasticity, and the adhesiveness with respect to a membranous model.

The physical properties of the material of the base material 22 are adjusted so as to match the physical properties of surrounding tissues such as blood vessels that are the targets of the membranous model.
In this embodiment, the penetration, fluidity, adhesiveness, stress relaxation, etc. are used as indicators, and finally the physical properties are brought closer to the living tissue by the operator's hand (catheter insertion feeling). Yes.
In the case of silicone gel, the physical properties can be adjusted by blending silicone oil as well as preparing the polymer skeleton.

  In addition to silicone gel, glycerin gel can also be used. This glycerin gel is obtained as follows. That is, gelatin is immersed in water, glycerin and carboxylic acid are added thereto, and the mixture is dissolved by heating. Filtration while the temperature is high, and when it reaches a temperature that does not affect the core, it is poured into the casing and allowed to cool.

Thereafter, the body cavity model in the core 11 is removed. A hybrid method was adopted as a removal method. That is, the sample is heated to flow the body cavity model material out of the opening, and acetone is injected into the cavity to dissolve and remove the body cavity model material.
Thereafter, the sample was heated in a constant temperature layer set at 120 ° C. for about 1 hour to remove the cloudiness of the membranous model (silicone rubber layer 15).

  As shown in FIG. 5, the three-dimensional model obtained in this way has a configuration in which the membranous model 15 is embedded in a base material 22 made of silicone gel. Since the silicone gel has physical properties close to those of living tissue, the membranous model will exhibit dynamic behavior equivalent to that of blood vessels.

  As a three-dimensional model according to another embodiment, one obtained by omitting the membranous model from the three-dimensional model can be given.

FIG. 6 shows the configuration of a catheter surgery simulator 1000 according to an embodiment of the present invention.
The catheter surgery simulator 1001 of this embodiment is generally composed of a container 1003, a translucent liquid 1001 having a refractive index close to that of the three-dimensional model 1002 of the present invention, and an imaging device 1004.
As the translucent liquid 1001, a mixed liquid of glycerin and water can be used. In addition, a mixed liquid of α-monobromonaphthalene and liquid paraffin can be used. In any case, it is necessary to adjust the mixing ratio of each liquid so that the refractive index of the resulting mixed liquid approximates the three-dimensional model.
The inside or part of the container 1003 is filled with a light-transmitting liquid 1001, and further, a part or all of the surrounding area of the three-dimensional model 1002 is immersed in the light-transmitting liquid 1001, so that the surrounding shape of the three-dimensional model is changed. It can be made substantially invisible. By capturing the three-dimensional model in this state with the imaging device 1004, an image close to a fluoroscopic image used during actual surgery can be obtained.

In this embodiment, the imaging device 1004 is arranged outside the container 1003. However, it is also possible to arrange the imaging device 1004 so that the lens portion of the imaging device 1004 is included inside the container 1003. This is because light is irregularly reflected on the surface of the container 1003, and thus the arrangement may improve the quality of the fluoroscopic image.
Further, the lens portion of the imaging device can be waterproofed and the lens portion can be disposed so as to be immersed in the translucent liquid 1001 inside the container 1003. This is because the light is irregularly reflected on the surface of the container 1003 or the surface of the three-dimensional model 1002, and thus the arrangement may improve the quality of the fluoroscopic image.

The light receiving unit 1008 includes an imaging device 1004 composed of a CCD or the like, an image synthesis device 1005 that processes a pseudo-perspective image captured by the imaging device 1004, and a display 1006 and a printer 1007 that output a synthesis result of the image synthesis unit 1005. Prepare.
In the image synthesizing apparatus 1005, the following three types of processing were performed according to the progress of the surgical simulation (see FIG. X). According to each of these processes, a fluoroscopic image at the time of surgery can be reproduced satisfactorily, and by performing a catheter surgery simulation while confirming this reproduced image, compared with the case of directly observing the three-dimensional model 1002 visually, Realistic surgical simulation was possible

The first process is a process for reproducing a fluoroscopic image in a normal state obtained during surgery.
In this processing, an image in which all or a part of the periphery of the three-dimensional model 1002 is immersed in the translucent liquid 1001 is captured (step 1-1), and monochrome gradation is performed (step 1-2). In this case, a combination of white and black and their intermediate colors was used for monochrome gradation, but other colors such as a combination of red and blue and their intermediate colors can also be used. A specific area in the image may be highlighted by including other colors or characters. However, in any case, it is preferable that the actual fluoroscopic image reproduces the color tone.

The second process is a process for reproducing a differential image (an image in which a non-interesting area is lost by image processing) used in actual surgery. In this processing, an image in which all or a part of the periphery of the three-dimensional model 1002 is immersed in the translucent liquid 1001 is captured as a background image (step 2-1), and after inserting a catheter or liquid, the same is performed again. An image is captured from the viewpoint (step 2-2). Then, by performing a difference operation (subtraction operation) between these images, only the region that has changed between these images is selectively visualized, and the other regions are removed from the image (step 2-3). ). Finally, by performing monochrome gradation (step 2-4), a difference image similar to that at the time of surgery was constructed. Then, Step 2-2 to Step 2-4 are continuously imaged, and each obtained image and the background image obtained in Step 2-1 are subjected to differential processing in real time, thereby being the same as during surgery. A differential perspective image was obtained.
Hereinafter, a specific use example of the second method will be described. As an example, the above-mentioned background image is obtained in advance before inserting the catheter into the interior of the three-dimensional model, and after the catheter is inserted, the remaining processing (step 2-2 to step 2-4) is repeated continuously. As a result, a differential fluoroscopic image in which only the catheter was selectively visualized was obtained. Thereby, it was possible to concentrate on the operation of the catheter and perform a surgical simulation.
As another example, by filling the lumen part with a translucent liquid 1001, an image in a state where the lumen part is substantially invisible is obtained as a background image, and dye is added to the lumen part. After the injection, the remaining processing (Step 2-2 to Step 2-4) was executed to obtain a fluoroscopic image in which only the lumen portion was selectively visualized. Thereby, a DSA (Digital Subtraction Angiography) image similar to that at the time of surgery was reproduced.
Here, the monochrome gradation processing is performed last, but after performing the monochrome gradation processing for each of the images obtained in step 2-1 and step 2-2, step 2-3 is performed. You can also.
Moreover, when the viewpoint of the imaging device was moved during the catheter surgery simulation, the process was re-executed from step 2-1, and the difference video was reconstructed.

The third process is a method for reproducing a road map image (image obtained by overlaying a blood vessel image at a specific time point on a surgical field image) used in actual surgery. In actual surgery, when the contrast medium is not injected, the body cavity region is not visualized on the fluoroscopic image, and thus the position and shape cannot be known. For this reason, the same region is visualized by injecting a contrast medium into the body cavity, and an image called a road map image is generated. By displaying this road map image as an overlay on the subsequent surgical image, an image capable of operating the catheter while confirming the position and shape of the body cavity is generated.
In the third processing of the present invention, both the periphery (part or all) of the three-dimensional model 1002 and the cavity portion (part or all) of the three-dimensional model 1002 are filled with the translucent liquid 1001 to form a three-dimensional model. Both the surrounding shape and the cavity shape of the model 1002 are substantially invisible. The image in this state is captured as a background image (step 3-1). Next, the cavity portion is visualized by injecting a dye into (a part or all of) the cavity region, and step 3-1 An image is acquired from the same viewpoint (step 3-2). Then, by performing a difference operation (subtraction operation) between these images, an image in which only the cavity portion of the three-dimensional model is selectively visualized is generated (step 3-3). By converting this image into a monochrome gradation (a gradation inversion process may also be performed), a road map image is generated (step 3-4). The road map image is displayed as an overlay on [0054] the fluoroscopic image obtained by the first process or [0055] the difference image obtained by the second process (step 3). -5) Reproduced the same roadmap video as in actual surgery. Using this road map image, a catheter insertion simulation was performed while visually confirming the position of the cavity at a specific moment.
In addition, when the viewpoint of the imaging device was moved during the surgery simulation, the process was re-executed from Step 3-1, and the road map video was reconstructed.

FIG. 7 shows a catheter surgery simulator 60 of another embodiment.
The catheter surgery simulator 60 of this embodiment includes a light source 61, a pair of polarizing plates 62 and 63, a one-wave plate 68, a three-dimensional model 1002 shown in FIG. 1, and a translucency having the same refractive index as the three-dimensional model. A light receiving unit 70 including a liquid 1001, a container 1003 that holds the translucent liquid, and an imaging device 71 is generally configured.
The light source 61 is preferably a white light source. Sunlight can also be used as a light source. It is also possible to use a monochromatic light source. The first polarizing plates 62 and 63 have polarization directions orthogonal to each other. Thereby, the photoelastic effect resulting from the internal stress of the three-dimensional model 21 can be observed on the second polarizing plate 63 side. By interposing the one-wavelength plate 68 between the pair of polarizing plates 62 and 63, a non-translucent member such as a catheter through which light near a wavelength of 530 nm passes through the second polarizing plate 63 as background light. Observed as a shadow. A wavelength shift filter represented by the one-wave plate 68 may be interposed between the first polarizing plate 62 and the three-dimensional model 21.
When the catheter is inserted into the cavity of the three-dimensional model 21, if the catheter interferes with the peripheral wall of the cavity, stress is generated in the peripheral wall of the cavity and a photoelastic effect (interference fringe) appears there. In addition, the stress state in the region around the aneurysm accompanying the deformation of the aneurysm during coil embolization can be simulated from the photoelastic effect.

  In this embodiment, the light source 61, the first polarizing plate 62, the three-dimensional model 21, and the second polarizing plate 63 are arranged on a straight line. However, the second polarizing plate 63 is shifted (that is, from the straight line). Can be shifted). This is because light diffusely reflects in the cavity of the three-dimensional model 21, and the photoelastic effect may be observed more clearly if the second polarizing plate 63 is shifted in the shape of the cavity.

The light receiving unit 70 includes an image pickup device 71 composed of a CCD or the like, an image processing device 70 that processes a photoelastic effect image picked up by the image pickup device 71, and a display 75 and a printer 77 that output a processing result of the image processing unit 70. Prepare.
The image processing apparatus 73 performs the following processing.
First, an image in an initial state where no external force is applied to the three-dimensional model 1002 is captured as a background image (step 1). Here, when the three-dimensional model 1002 is formed of a material having a high photoelastic coefficient, a photoelastic effect may be generated by its own weight. For this reason, after capturing the interference fringe image by the photoelastic effect when light is applied from the light source 61 and further external force is applied (for example, when a catheter is inserted) (step 3), the background image is differentially processed from this. (Step 5) removes the photoelastic effect due to its own weight.

  Next, when the three-dimensional model 21 is formed of a material having a high photoelastic coefficient, fine interference fringes appear in a repetitive pattern depending on the internal stress, and the stress recognition becomes complicated. For this reason, the image processing apparatus 73 quantifies the internal stress by counting the number of the patterns per unit area (step 7).

Next, by applying the three image processing methods described from [0054] to the image obtained through the second polarizing plate 63, a fluoroscopic image at the time of surgery is reproduced, Then, a color corresponding to the numerical value is overlaid and displayed on the portion where the internal stress is generated (step 9). As a result, in the catheter insertion simulation, an environment in which the state during the operation can be recognized from the stress surface while confirming the same operation image as the actual operation was constructed.
In this embodiment, the interference fringes observed by the light receiving unit 70 are subjected to image processing and then displayed as an overlay on the fluoroscopic image. However, the stress visualization image obtained by the imaging device 71 can be obtained without performing image processing. It is also useful to display an overlay directly on the fluoroscopic image.

  The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

  FIG. 1 shows a three-dimensional model of an embodiment of the present invention.   FIG. 2 is a perspective view showing the core of the embodiment.   FIG. 3 is a perspective view showing the guide portion.   FIG. 4 shows a three-dimensional model of another embodiment.   FIG. 5 shows a three-dimensional model of another embodiment.   FIG. 6 is a schematic diagram showing the configuration of the catheter surgery simulator of the embodiment of the present invention.   FIG. 7 is a schematic diagram showing the configuration of a catheter surgery simulator according to another embodiment of the present invention.

Explanation of symbols

13 Core 22 Body cavity model 12 Silicone rubber layer (film model)
11 3D model 1000, 60 Catheter surgery simulator

Claims (3)

A catheter surgery simulator that generates a fluoroscopic image using a translucent three-dimensional model in which at least a peripheral region reproducing a body cavity is formed of an elastic material and a catheter can be inserted,
The aforementioned three-dimensional model;
A translucent liquid having a refractive index approximating the three-dimensional model;
A container for holding the translucent liquid;
An imaging device for observing the three-dimensional model,
A catheter surgery simulator characterized by being able to perform fluoroscopic imaging of a catheter inserted into the three-dimensional model.   2. The catheter surgery simulator according to claim 1, wherein the translucent liquid is a mixed liquid of glycerin and water. The catheter surgery simulator according to claim 1, wherein at least a peripheral region of the cavity that reproduces the body cavity is formed of an elastic material, and a fluoroscopic image is generated using a translucent three-dimensional model in which a catheter can be inserted. ,
A polarization filter; and a phase shift filter disposed inside the polarization filter. The catheter inserted into the stereo model can be radiographed and generated in light passing through a region around the cavity of the stereo model. A catheter surgery simulator comprising means for detecting a photoelastic effect.