JP4997385B2 - Catheter surgery simulator - Google Patents

Description

  The present invention relates to a catheter surgery simulator.

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 reproducing the cerebral vascular lumen. Proceedings of the 12th Annual Meeting of the Japan Society for Computer Aided Surgery, 2003

According to the above model, it is possible to visually observe the dynamic deformation of the cavity portion that reproduces the body cavity with respect to the catheter and liquid insertion simulation. I can't get any information.
Accordingly, an object of the present invention is to make it possible to observe a stress state in a peripheral region of a cavity portion in a three-dimensional model.

The present invention has been made to solve the above problems, and is configured as follows.
A three-dimensional model stress observation device for detecting a photoelastic effect generated in light passing through a light-transmitting three-dimensional model in which at least a peripheral region that reproduces a body cavity is formed of an elastic material and allows insertion of a catheter. ,
A polarized light source and a corresponding polarizing filter;
A phase shift filter disposed inside the polarization light source and the corresponding polarization filter,
A catheter surgery simulator characterized in that a catheter inserted into the three-dimensional model can be viewed.

According to the three-dimensional model stress observation apparatus configured as described above, when stress is applied to the area around the cavity of the three-dimensional model in a catheter or liquid insertion simulation, a photoelastic effect is generated and the stress state is observed. be able to.
In addition, for example, by arranging a phase shift filter between the first polarizing filter constituting the polarized light source and the second polarizing filter on the viewer side, a part of the light transmitted through the first polarizing filter is 2 can be transmitted through the polarizing filter. At this time, when the catheter is inserted into the three-dimensional model, the catheter does not transmit light, and the catheter is observed as a shadow. Of course, a photoelastic effect is observed in a region around the three-dimensional model in which a stress change is caused by the catheter. If this phase shift filter is not present, the light from the light source is completely blocked by the pair of polarizing filters, and only the light modulated by the photoelastic effect is transmitted through the second polarizing filter and can be observed. In this case, the catheter itself cannot be observed.

  It is preferable to use a so-called one-wave plate or two-wave plate as the wavelength shift filter. The one-wavelength plate is also called a sensitive color plate, which increases the observation sensitivity of the photoelastic effect.

Hereinafter, each component of the invention will be described in detail.
(3D model forming material)
In order to observe the stress state of the three-dimensional model by photoelasticity, at least a portion of the three-dimensional model that requires observation of the stress state is formed of an isotropic material. The three-dimensional model has translucency.
Examples of such photoelastic materials include thermosetting of silicone resins (epoxy resins), polyurethane resins, unsaturated polyesters, phenol resins, urea resins, etc. in addition to elastomers such as silicone rubber (silicone elastomer) and thermosetting polyurethane elastomers. A thermoplastic resin such as polymethyl methacrylate can be used singly or in combination.
When a catheter or liquid is inserted into a cavity of a three-dimensional model, in order for the stress state in the area around the cavity to be observed as a photoelastic effect, at least the area must be formed of an elastically deformable material. There is. Of course, the three-dimensional model can be formed of a material that is elastically deformable as a whole.
As a material for forming such a three-dimensional model, it is easy to deform with insertion of a catheter or the like (that is, the longitudinal elastic modulus is large), and a large change in photoelastic effect can be observed even with slight deformation (that is, the photoelastic system coefficient is Large) material is preferred. 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 tomography. 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 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 data), but obtained by other imaging methods. 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 stacked based on the shooting interval at the time of shooting. 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, the 3D shape data is constructed from the tomographic data. However, when the 3D shape data is given as the data from the beginning, 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 organ, respiratory organ, digestive organ, urogenital organ, endocrine organ, nerve, sensory organ, etc.). And a cavity formed by a geometric arrangement of these organs and body walls. Therefore, the lumens of organs such as the 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 Thermosetting resins such as polyurethane, unsaturated polyester, phenolic resin, urea resin, and thermoplastic resins such as polymethyl methacrylate can be used alone or in combination. 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 transparent and has elasticity and flexibility close to a 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.
From the viewpoint of observing the photoelastic effect, the membranous model is preferably formed with a substantially uniform thickness as a whole.

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. 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 cerebral blood vessel model is targeted as a membranous model, the adhesion (adhesive 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. 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. 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 reducing its visibility. 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, by forming an oily film such as oil or wax on the peripheral wall of the cavity, the peripheral wall of the cavity can be hydrophobized.

  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.

(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.

According to the study by the present inventors, a phase shift filter is arranged between the second polarizing filter on the observation side and the quarter wavelength filter, and the phase shift filter is further arranged with respect to the optical axis of the quarter wavelength filter. It is preferable to incline approximately 22.5 degrees.
Such a configuration is shown in FIG. In FIG. 2, reference numeral 201 is a white light source, reference numerals 203 and 204 are polarization filters, reference numerals 205 and 206 are quarter wavelength filters, 207 is a three-dimensional model to be observed, and 209 is a phase shift filter (in this example, a two-wavelength plate). ).
When the tilt angle of the phase shift filter 209 is ψ = ± 5 degrees to ± 40 degrees, more preferably ψ = ± 22.5 degrees, the photoelastic effect (light color (light color)) observed in the second polarizing filter 204 is obtained. From the wavelength)), the stress to be observed and its direction can be specified.
This is due to the following reason.
In the configuration of FIG. 2, the observed light intensity I is expressed by the following formula 1.

Formula 1

ここに、θは応力の方向を示し、Ｒｅは光弾性効果により生じた位相シフトによる遅延(Retardation)を示す。なお、このＲｅは応力強さに対応する。
ψ＝２２．５として、上記式１にＲＧＢの各波長を代入したとき、観察される光の色（波長）は応力の方向と応力の強さとを反映している。換言すれば、観察された光の色から応力の方向と応力の強さが特定できる。観察された光と応力方向及び応力強さとの関係は図３のマップで表される。なお、紙面の都合上、図３は白黒表記となったが、実際には、図３の全領域に渡り色変化が認められ、図３の縦軸（応力方向）の任意の座標と横軸（応力強さ）の任意の座標とで指定される色（波長）は実質的に１つに特定される。このようなカラーマップはψ＝±５度〜±４０度のとき、より鮮明にはψ＝±２２．５度のとき得られる。
他方、ψ＝０度あるいはψ＝９０度のときは、図４Ａに示す通り、縦軸の９０度を中心にして上下対称の色分布のなるので、観察された色から応力方向や応力強さを特定することは出来ない。またψ＝±４５のときは、図４Ｂに示す通り、前記位相シフトフィルタの効果を得ることができないため、カテーテルの影を観察することが困難である。
また、本発明者らの検討によれば、ψ＝±２２．５のとき、光源をＧ（緑色系）の光とすると、図３のマップにおいて、緑色の明るさ（強さ）が横軸に対応して分布していることがわかった。実際には横軸のほぼ中央で最も明るく、左右に移行するに従い明るさが低減する。立体モデルにかかる最高応力はほぼＲｅ＝２６５〜４００程度であり、それを超えると破損するおそれが強い。従って、緑色の明るさに注目すれば、立体モデルにかかっている応力の強さを特定することができる。これにより、オペレータはカテーテル手術シミュレーションを行なうときの立体モデルの応力状態を、リアルタイムでかつ直感的に把握することができる。

Here, θ indicates the direction of stress, and Re indicates a delay due to phase shift caused by the photoelastic effect. This Re corresponds to the stress intensity.
When ψ = 22.5 and the respective wavelengths of RGB are substituted into Equation 1, the observed light color (wavelength) reflects the direction of stress and the strength of stress. In other words, the direction of stress and the strength of stress can be specified from the color of the observed light. The relationship between the observed light and the stress direction and stress intensity is represented by the map in FIG. Note that, due to space limitations, FIG. 3 is shown in black and white, but in reality, color change is recognized over the entire area of FIG. 3, and arbitrary coordinates and abscissa on the vertical axis (stress direction) in FIG. The color (wavelength) specified by an arbitrary coordinate of (stress intensity) is substantially specified as one. Such a color map is obtained when ψ = ± 5 degrees to ± 40 degrees, and more clearly when ψ = ± 22.5 degrees.
On the other hand, when ψ = 0 degrees or ψ = 90 degrees, as shown in FIG. 4A, the color distribution is vertically symmetric about 90 degrees on the vertical axis, so the stress direction and stress intensity from the observed color. Cannot be specified. When ψ = ± 45, it is difficult to observe the shadow of the catheter because the effect of the phase shift filter cannot be obtained as shown in FIG. 4B.
Further, according to the study by the present inventors, when ψ = ± 22.5, when the light source is G (green) light, the brightness (intensity) of green in the map of FIG. It was found that it was distributed corresponding to. Actually, it is brightest at the approximate center of the horizontal axis, and the brightness decreases as it moves left and right. The maximum stress applied to the three-dimensional model is about Re = 265 to 400, and if it exceeds that, there is a strong possibility of breakage. Therefore, if attention is paid to the brightness of green, the strength of stress applied to the three-dimensional model can be specified. Thereby, the operator can grasp in real time and intuitively the stress state of the three-dimensional model when performing the catheter surgery simulation.

(First embodiment)
In order to obtain three-dimensional data related to the shape of the cerebral blood vessel to be modeled and the cerebral artery, which is the affected part, 0.35 × Imaging was performed with a helical scan type X-ray CT apparatus having a spatial resolution of 0.35 × 0.5 mm. The three-dimensional data obtained by photographing is a two-dimensional image of 256 gradations having a resolution of 512 × 512 and arranged at equal intervals in the body axis direction (tomographic imaging) for delivery to the three-dimensional CAD software. 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 intravascular 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 12 (see FIG. 6) (see FIG. 5). 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 is enlarged in diameter, and this portion is exposed on the surface of the three-dimensional model to form a large-diameter opening 25 (see FIG. 6).

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 formation of the final layer, a layered modeling model (body cavity model 12) of the cerebral vascular lumen region was created.
Further, the surface of the body cavity model 12 is processed and smoothed.

A silicone rubber layer 15 having a thickness of about 1 mm was formed on the entire surface of the body cavity model 12 (see FIG. 6). The silicone rubber layer 15 is obtained by drying the body cavity model 12 dipped from the body cavity model 12 and rotating the body cavity model. This silicone rubber layer becomes a membranous model.
In this embodiment, the entire surface of the body cavity model 12 is covered with the silicone rubber layer 15, but a desired portion of the body cavity model 12 may be partially covered with the silicone rubber layer 15.

A core 11 formed by covering the body cavity model 12 with a film model composed of a silicone rubber layer 15 is set in a rectangular casing 24. The casing 24 is made of a transparent acrylic plate. The material of the base material 22 is injected into the casing and gelled.
As a material for the substrate 22, a two-component mixed silicone gel was used. This silicone gel is transparent and elastic, and has physical properties very close to the soft tissue surrounding 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 12 in the core 11 is removed. A hybrid method was adopted as a removal method. That is, the sample is heated to cause the body cavity model material to flow out of the opening 25, 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 FIGS. 7 and 8, the three-dimensional model 21 thus obtained has a configuration in which the film 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 15 exhibits dynamic behavior equivalent to that of blood vessels.

As a three-dimensional model according to another embodiment, one obtained by omitting the membranous model 15 from the three-dimensional model 21 can be cited.
In this case, it is preferable to use gelatin having a high photoelastic coefficient as the substrate.

FIG. 9 shows the configuration of a catheter surgery simulator 60 according to an embodiment of the present invention.
The catheter surgery simulator 60 of this embodiment is mainly composed of a light source 61, a pair of polarizing plates 62 and 63, a one-wave plate 68, the three-dimensional model 21 shown in FIG.
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-wave plate 68 between the pair of polarizing plates 62 and 63, a non-transparent member such as a catheter that transmits light in the vicinity of a wavelength of 530 nm as background light and passes through the second polarizing plate 63 is shaded. Observed. 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 device 73 performs the following processing (see FIG. 10).
First, an image in an initial state where no external force is applied to the three-dimensional model 21 is captured as a background image (step 1). When the three-dimensional model 21 is formed of a material having a high photoelastic coefficient, a photoelastic effect may be generated by its own weight. Therefore, after capturing an interference fringe image due to the photoelastic effect when light is applied from the light source 61 and an external force is applied (for example, when a catheter is inserted) (step 3), the background image is differentially processed (step 3). Step 5).

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. The image processing device 73 digitizes the internal stress by counting the number of the patterns per unit area (step 7). Then, in the image relating to the shape of the three-dimensional model 21 obtained through the second polarizing plate 63, the portion corresponding to the internal stress is given a color corresponding to the numerical value and is externally displayed (step 9).
In this embodiment, the interference fringes due to the photoelastic effect are image-processed by the light receiving unit 70, but the observer may observe the interference fringes directly or via the imaging device 71.

FIG. 11 shows a catheter surgery simulator 80 of another embodiment. Elements that are the same as those shown in FIG. 12 are given the same reference numerals, and descriptions thereof are omitted.
In this embodiment, a first 1/4 polarizing plate 82 is interposed between the first polarizing plate 62 and the three-dimensional model 21, and a second 1/2 is provided between the three-dimensional model 21 and the second polarizing plate 63. Four polarizing plates 83 are interposed. Thereby, the photoelastic effect of the three-dimensional model 21 can be observed based on the circularly polarized light. According to the observation of the photoelastic effect based on the circularly polarized light, the influence of the stress direction does not appear in the interference fringes, so that the attitude control of the three-dimensional model is facilitated.

In the above example, the imaging apparatus 71 is opposed to the second polarizing plate 62 for observation, but this can also be observed directly by a human.
FIG. 12 shows an example suitable for visual observation. In this example, glasses 90 are prepared. The lens portion of the glasses 90 has a two-layer structure. As shown in FIG. 12B, a second polarizing plate 63 is disposed on the viewer side, and a one-wave plate 68 is disposed outside the second polarizing plate 63. ing.
When the light source 61 is turned on without wearing the glasses 90, the three-dimensional model 21 is illuminated with the light that has passed through the first polarizing plate 62, and the structure of the catheter and its blood vessel structure can be visually observed. Become. On the other hand, when the glasses 90 are put on, the configuration of FIG. 9 is basically formed, so that the state of the catheter and the photoelastic effect corresponding to the stress state of the three-dimensional model by the catheter can be observed simultaneously.
In this embodiment, the glasses 90 are adopted, but a plate in which the second polarizing plate and the phase shift filter are laminated may be prepared from the observer side.
When a phase shift filter typified by a single wavelength plate is disposed between the first polarizing plate 62 and the three-dimensional model 21, the lens portion of the glasses may be formed only from the second polarizing plate.

FIG. 13 shows a catheter surgery simulator 160 according to another embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the element same as FIG. 9, and the description is abbreviate | omitted. In FIG. 13, a display 175 and a printer 177 constitute an output unit that outputs the stress state of the membranous model. The lamp device 178 and the speaker device 179 constitute an output unit that outputs an alarm. The photoelasticity observation unit is configured by the pair of polarizing plates 62 and 63 and the one-wave plate as the phase shift filter.
Next, the operation of the catheter surgery simulator 160 shown in FIG. 13 will be described based on the flowchart of FIG.
The portion of the second polarizing plate 63 facing the three-dimensional model 21 is imaged by the imaging device 71, and the brightness for each pixel is stored in a predetermined area of the memory of the image processing device as a feature value for specifying the state quantity of the film model. (Step 11). In step 15, the pixel with the highest luminance is extracted (step 15), and the stress corresponding to the highest luminance is specified with reference to a previously prepared table or relational expression (step 17). Next, the level of stress specified according to a predetermined rule is specified (step 19). For example, it is possible to classify the stress into three stages, that is, a safety stage, a caution stage, and a danger stage from the one with a lower stress.

The specified stress level can be displayed on the display 175 in the form of numerical values, characters, bar graphs, or the like (step 21). Of course, the imaging screen of the imaging device 71 can be displayed on the display 175 in real time.
Depending on the specified stress level, the stage can be voice-guided through the speaker device 179. It is preferable to give the voice guidance when the stage changes (step 23).
Further, the lamp device 178 can be turned on according to the specified level (step 25). For example, a green lamp is lit in the safety stage, a yellow lamp is lit in the caution stage, and a red lamp is lit when the danger stage is reached.
By outputting the alarm in this way, the operator can concentrate on the catheter insertion work.

In the above, it is also possible to specify the stress from the brightness for each pixel, count the pixels having the stress exceeding the predetermined threshold, and specify the stress level based on the count result. Further, it is possible to calculate a stress change for each pixel, count the stress change exceeding a predetermined threshold value, and specify the stress level based on the count result.
Furthermore, the feature value is a calculated value obtained by multiplying the luminance of a pixel in the image captured by the imaging device by a weighting factor based on a certain rule and adding the luminance to a predetermined region or the entire region of the image. You can also.
In the above description, the stress is obtained from the brightness. However, the brightness itself is calculated, that is, based on the magnitude of the brightness and the rate of change thereof, the level is determined without any stress calculation, and an alarm (voice guidance) is obtained. Or lamp) can be operated.

Furthermore, the stress can be specified from the luminance obtained for each pixel, and the stress can be integrated in time series. Thereby, the stress (stress history) accumulated in the portion corresponding to the pixel in the membranous model can be displayed. Also. Depending on the amount of accumulated stress (for example, when the accumulated stress exceeds a predetermined threshold), the alarm output can be operated.
The image processing as described above is possible because the sensitivity is improved and the image processing can be performed accurately by interposing the one-wave plate.

FIG. 15 shows an embodiment that simulates the creation of a road map in catheter surgery.
In step 31, a contrast agent is poured into the blood vessel portion (film model portion) of the three-dimensional model 21 to capture an image of the three-dimensional model 21. At this time, at least one of the polarizing plates 62 and 63 is removed, and preferably the polarizing plates 62 and 63 and the one-wave plate 68 are removed, and the light from the light source 61 is transmitted through the three-dimensional model 21. The three-dimensional model into which the contrast agent is introduced is photographed with the blood vessel portion stained, and the image is stored (step 31).
Thereafter, in the state of FIG. 13, the photoelastic effect of the three-dimensional model, particularly the film model, is photographed by the photographing device 71 (step 33).
The photographed image showing the photoelastic effect is displayed with the contrast agent introduction image as a background (step 35). Thereby, the reliability of roadmap creation in catheter surgery can be confirmed.

FIG. 16 shows the configuration of a simulator 300 of another embodiment. In addition, the same code | symbol is attached | subjected to the element same as FIG. 11, and the description is partially abbreviate | omitted.
In this embodiment, a two-wave plate 301 is present between the second quarter-wave plate 83 and the second polarizing plate 63. The two-wave plate is inclined 22.5 degrees with respect to the optical axis of the quarter-wave plate.
Such a configuration corresponds to the configuration of FIG. 2 described above. When the light source color is white light, by comparing the color (wavelength) of the light imaged by the imaging device 71 with the color map shown in FIG. The direction is specified.
In the apparatus 300 according to the embodiment, the color map of FIG. 3 is stored in the memory 303. An arithmetic expression for calculating stress from the value of the horizontal axis Re in FIG.
Reference numeral 305 denotes a pointing device such as a mouse, and a desired portion can be designated with the cursor 310 on the display 75 that displays a captured image of the imaging device 71 (see FIG. 17).
The image processing apparatus 73 recognizes the color of the part designated by the cursor 310 and compares the color with a color map (see FIG. 3) stored in the memory 303 to specify the direction and magnitude of the stress. . Note that the magnitude of the stress can be obtained by substituting the delay Re specified in FIG. 3 into the relational expression stored in the memory 303. Then, as shown in FIG. 17, a pop-up window 320 is opened, where the magnitude of the stress at the portion designated by the cursor 310 is numerically displayed, and the direction is indicated by an arrow.

  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 is an explanatory diagram of the photoelastic effect. FIG. 2 is a schematic configuration diagram of a simulator according to one aspect of the present invention. FIG. 3 shows a color map obtained by the simulator of FIG. 2 when ψ = 22.5 degrees. FIG. 4 shows a color map obtained by the simulator of FIG. 2 when ψ = 0 degrees and ψ = 90 degrees. FIG. 5 is a perspective view showing the core 11 of the embodiment. 6 is a cross-sectional view taken along line AA in FIG. 5 and shows the configuration of the core. FIG. 7 shows a three-dimensional model of the embodiment of the present invention. FIG. 8 is a cross-sectional view taken along the line BB of FIG. 7 and shows a state in which the membranous model is embedded in the base material. FIG. 9 is a schematic diagram showing the configuration of the catheter surgery simulator of the embodiment of the present invention. FIG. 10 is a flowchart showing the operation of the light receiving unit of the catheter surgery simulator of the embodiment. FIG. 11 is a schematic diagram showing the configuration of a catheter surgery simulator according to another embodiment of the present invention. FIG. 12 is a schematic diagram showing the configuration of a catheter surgery simulator according to another embodiment of the present invention. FIG. 13 is a schematic diagram showing the configuration of a catheter surgery simulator according to another embodiment of the present invention. FIG. 14 is a flowchart showing the operation of the catheter surgery simulator. FIG. 15 is a flowchart showing another operation of the catheter surgery simulator. FIG. 16 is a schematic diagram showing a configuration of a catheter surgery simulator of another embodiment. FIG. 17 shows a display mode of the display 75.

Explanation of symbols

11 Core 12 Body cavity model 15, 55 Silicone rubber layer (film model)
21 Three-dimensional model 22 Base material 60, 80, 160, 300 Catheter surgery simulator 61 Light source 62, 63 Polarizing plate 68 1 wavelength plate 70 Light receiving part 82, 83 1/4 wavelength plate

Claims (13)

A three-dimensional model stress observation device for detecting a photoelastic effect generated in light passing through a light-transmitting three-dimensional model in which at least a peripheral region that reproduces a body cavity is formed of an elastic material and allows insertion of a catheter. ,
A polarized light source and a corresponding polarizing filter;
A phase shift filter disposed inside the polarization light source and the polarization filter, the phase shift filter enabling a part of the light from the polarization light source to pass through the polarization filter as a background color, and
A catheter surgery simulator characterized in that both the photoelastic effect and the shadow of the catheter inserted into the three-dimensional model can be seen.   The catheter surgery simulator according to claim 1, wherein the phase shift filter includes a single wavelength plate or a dual wavelength plate.   A pair of quarter wavelength filters are arranged inside the polarized light source and the polarization filter so as to realize circular deflection method observation, and the phase shift filter is arranged between the pair of quarter wavelength filters. The catheter surgery simulator according to claim 1 or 2, wherein   The catheter surgery simulator according to claim 1 or 2, wherein the polarizing filter and the phase shift filter are laminated to form a window portion of glasses.   The film-like model is surrounded by a base material that is made of a gel that hardly produces a photoelastic effect as compared with the film-like model and has adhesion to the film-like model. 5. The catheter surgery simulator according to any one of 4 above.   A translucent casing for housing the base material, wherein the base material is further provided with a casing having a margin for allowing free deformation of the membranous model between the casing and the membranous model; The catheter surgery simulator according to claim 5. The film model is made of urethane resin or urethane elastomer,
The catheter surgery simulator according to claim 5, wherein the base material is made of silicone gel.   The catheter surgery simulator according to claim 1, wherein the polarized light source includes a white light source and the polarizing filter. Insert the catheter into a translucent three-dimensional model in which at least the area around the cavity that reproduces the body cavity is made of an elastic material,
Placing the three-dimensional model between a polarized light source and a corresponding polarizing filter to produce a photoelastic effect corresponding to the stress generated in the surrounding region by the catheter;
By interposing a phase shift filter between the polarization light source and the polarization filter, the shadow of the catheter inserted into the three-dimensional model together with the photoelastic effect can be observed.
A method for observing stress in a three-dimensional model. An imaging device for imaging the photoelastic effect of the three-dimensional model;
An image processing device that processes an image picked up by the image pickup device and generates a feature quantity that identifies a state of the three-dimensional model;
An output unit that outputs the feature value generated by the image processing apparatus or outputs an alarm based on the feature value;
The catheter surgery simulator according to claim 1, further comprising: The feature amount is a luminance value of a pixel, or a calculated value obtained by multiplying the luminance of the pixel by a weighting factor based on a certain rule and adding them together for pixels in a certain region, The catheter surgery simulator according to claim 10 . The catheter surgery simulator according to claim 10 or 11 , further comprising means for accumulating the feature quantities specified by the image processing apparatus. Means for storing an image of a state in which a contrast medium is introduced into the membranous model,
The output unit displays the photoelastic effect captured by the imaging device over the image,
The catheter surgery simulator according to claim 10 .

Images