JP7554399B2 - Modeling method - Google Patents

Description

The present invention relates to a molding method.

Three-dimensional modeling technology has made remarkable progress, and various 3D printers using methods such as fused deposition modeling, binder jetting, photolithography, powder sintering, and material jetting are used in the manufacturing industry. In addition to the conventional metals and resins, a variety of materials have been developed as materials for use in 3D printers. New applications for these various materials have also been proposed, and applications are expected not only in the industrial field but also in the medical and healthcare fields. Examples of applications of 3D printers in the medical field include, for example, the creation of implantable artificial bones using titanium, hydroxyapatite, PEEK, etc., and research into artificial organs by direct cell layering. Examples of applications of 3D printers in the healthcare field include, for example, applications to hearing aids and prosthetic limbs that need to reflect the unique shapes of each individual.

Another application of 3D printers in the medical field is the use of models that mimic the shape of actual organs or living organisms for the purpose of surgical training and simulation. The background to the expected application to such models is that medical equipment has been developed in recent years, and minimally invasive medical treatments that place less strain on patients, such as catheters, endoscopes, and robot assistance, are becoming mainstream, replacing the traditional medical treatments that involve large incisions and removal. Surgical operations using these medical equipment require very advanced technology and expertise, so the importance of surgical training using appropriate models is recognized from the perspective of preventing medical accidents. Furthermore, in difficult surgeries that are rarely performed, if a model that reproduces the details of the target area can be obtained in advance, it will be possible to perform detailed preoperative simulations.

Conventionally known models that mimic organs include models that are made with a 3D printer and are made of hard materials such as acrylic resins and urethane resins. However, hard materials are hard, and it is difficult to reproduce the texture of actual organs.
Other conventional models that mimic organs and the like include models that are made by a casting method using a mold and are made of an aqueous gel such as silicone elastomer and polyvinyl alcohol, as disclosed in Patent Document 1. When made by the casting method, there is a wide range of material options, and it is possible to make it using a material such as polyvinyl alcohol that has a texture similar to that of an actual organ. However, since the casting method is a method of integrally forming an organ using a single material, it is difficult to reproduce the distribution of physical properties within the organ that occurs based on the part of the organ to be made, the diseased area, etc.
Furthermore, since it is difficult to measure the texture of an actual organ by direct contact, it is generally necessary to match the texture of the organ to a similar one based on the results of interviews with doctors. However, since the texture information differs for each patient interviewed, it is difficult to create a model that reproduces the texture of a specific patient's organ.

The present invention aims to provide a method for forming a three-dimensional object that accurately reproduces the biological properties obtained by measuring a living body.

The present invention relates to a modeling method having a modeling step of using a 3D printer to create a three-dimensional object based on medical 3D data of a living body, the medical 3D data being created based on medical image data acquired by photographing the living body with a medical imaging device and on biological properties acquired by performing MRE measurement on the living body, and the three-dimensional object having a distribution of strength properties corresponding to the distribution of the biological properties.

The present invention provides a modeling method that can produce a three-dimensional object that accurately reproduces the biological properties obtained by measuring a living body.

FIG. 1 is a schematic diagram showing an example of a medical image dataset. FIG. 2 is a schematic diagram showing an example of medical 3D data. FIG. 3 is a schematic diagram showing an example of medical 3D data. FIG. 4 is a schematic diagram showing an example of regional medical 3D data acquired by dividing the medical 3D data into voxel regions. FIG. 5 is a schematic diagram showing an example of data in STL format acquired by converting regional medical 3D data into a surface model. FIG. 6 is a schematic diagram showing an example of data in FAV format acquired by converting regional medical 3D data into the FAV format. FIG. 7 is a schematic diagram showing an example of seven-level strength properties expressed by the arrangement patterns of the high-strength shaping composition and the low-strength shaping composition. FIG. 8 is a schematic diagram showing an example of a water-swellable layered clay mineral as a mineral, and a state in which the water-swellable layered clay mineral is dispersed in water. FIG. 9 is a schematic diagram showing an example of a modeling apparatus for a hydrogel three-dimensional object. FIG. 10 is a schematic diagram showing an example of a hydrogel three-dimensional object being peeled off from a support.

1. Modeling Method The modeling method of the present invention includes a modeling step of modeling a three-dimensional object (also referred to as a "model") using a 3D printer based on medical 3D data of a living body. The modeling method of the present invention may also include, as necessary, an acquisition step of acquiring medical 3D data of the living body and a generation step of generating 3D data for modeling based on the medical 3D data, as steps executed prior to the modeling step. Furthermore, the modeling method of the present invention may also include, as necessary, an evaluation step of evaluating the accuracy of the modeled three-dimensional object, as a step executed after the modeling step.
In the present disclosure, the term "living body" refers to at least a part of a human or non-human organism, and the number of subjects may be one or more. Note that at least a part of a human or non-human organism refers to, for example, a predetermined region in a living body, such as the chest, a predetermined organ in a living body, etc.
In addition, in the present disclosure, "creating a three-dimensional object using a 3D printer based on medical 3D data of a living body" is not limited to the case of directly using medical 3D data, such as inputting the medical 3D data into a 3D printer to create a three-dimensional object, but also refers to the case of indirectly using medical 3D data, such as inputting 3D data for modeling generated based on the medical 3D data into a 3D printer to create a three-dimensional object.

(1) Acquisition step The modeling method of the present invention preferably includes an acquisition step of acquiring medical 3D data of a living body. In the present disclosure, "medical 3D data" refers to data created based on at least medical image data acquired by photographing a living body with a medical imaging device and biological properties acquired by MRE measurement of the living body. That is, the acquisition step of acquiring medical 3D data of a living body includes an imaging step of acquiring medical image data by photographing the living body with a medical imaging device, a measurement step of acquiring biological properties by MRE measurement of the living body, and a creation step of creating medical 3D data based on the medical image data and the biological properties.

(I) Photographing Process The photographing process is a process of acquiring medical image data by photographing a living body with a medical imaging device. The medical imaging device is also called a modality, and is a device that scans a living body as a subject to acquire medical image data. Examples of the medical imaging device include a CT (Computed Tomography) device, an MRI (Magnetic Resonance Imaging) device, and an ultrasonic diagnostic device. Among these, it is preferable to use an MRI device from the viewpoint of also performing MRE measurement in the measurement process described later. The medical imaging device performs slice tomography to photograph a cross section of the living body multiple times. As a result, as shown in FIG. 1, multiple medical image data, which are images showing the cross sections of the living body, can be acquired. Each of these multiple medical image data (also called a "medical image data set") is preferably an image in the DICOM format, which is an international standard for medical image exchange. In addition, the medical image data includes image density information indicating the image density acquired by the medical imaging device. The image density is, for example, a CT value (X-ray transmittance) when a CT device is used as the medical imaging device, an MRI signal value when an MRI device is used, and reflection intensity when an ultrasound diagnostic device is used.

(II) Measuring step The measuring step is a step of acquiring biological properties by MRE measurement of a biological body. MRE measurement refers to measurement by a method of magnetic resonance elastography (MRE). This method is a non-invasive method of measuring the viscoelastic distribution inside a biological body by generating shear waves inside the biological body using a vibration device and taking an image with an MRI device. That is, the biological property acquired by MRE measurement of a biological body is preferably viscoelasticity. In addition to the method of performing MRE measurement, a method of performing measurement by ultrasonic elastography can be mentioned as a method of acquiring viscoelasticity of a biological body. In this regard, while the information obtained by measurement by ultrasonic elastography is one-dimensional, the information obtained by MRE measurement is two-dimensional, and 3D data can be easily generated, so that MRE measurement is preferable. In addition, when the measurement target is an organ such as the heart or blood vessels that itself undergoes periodic motion, a method of measuring the amount of deformation of the organ accompanying this motion and estimating the biophysical properties from the measured values based on a mechanical model or the like can also be mentioned. However, the biophysical properties obtained by this method are merely estimated values, and are inferior to MRE measurement in terms of accurate information acquisition of the living body. In addition, this method can be used only when the measurement target is an organ that undergoes periodic motion such as the heart or blood vessels, so MRE measurement is preferable in that organs that do not undergo periodic motion or organs for which it is difficult to measure the amount of deformation accompanying periodic motion can also be used as measurement targets. In addition, MRE measurement is often included in the system as an optional function of the MRI device, and is also preferable in that the imaging process and the measurement process can be performed by the same MRI device. In addition to this, the imaging process by the MRI device and the measurement process by the MRI device can be performed almost simultaneously. It is preferable in that the burden on the subject such as a patient can be reduced by performing them almost simultaneously, and that the time of acquiring medical image data and the time of acquiring biophysical properties are almost simultaneous, thereby obtaining accurate information on the living body. In particular, the latter point is an important point considering that the subject of imaging and measurement is a living body that is prone to change over time in terms of shape, physical properties, etc. Note that "almost simultaneously" refers to a case where the imaging process and the measurement process overlap at least partially, or where both the imaging process and the measurement process can be performed by using an MRI device once. In addition, MRE measurement is preferable in that it can be performed on a living body, and therefore the physical properties of the organ in the living body can be obtained in a state where blood pressure is applied.

(III) Creation Process The creation process is a process of creating medical 3D data based on the medical image data acquired in the imaging process and the biological properties acquired in the measurement process. The medical 3D data is information including a plurality of voxels created based on the medical image data, image density information indicating the image density in the medical image data assigned to each voxel, and biological property information indicating the biological properties assigned to each voxel. In other words, the medical 3D data is information in which the voxels, the image density information, and the biological property information are associated with each other.

A method for creating medical 3D data will be specifically described.
First, medical 3D data corresponding to 3D image processing is created from medical image data acquired in the imaging process by a medical imaging device or an image processing device related to the medical imaging device (also referred to as "medical imaging device, etc."). Medical 3D data is a collection of voxels including at least one minimum unit such as a cube as shown in FIG. 2, and various information can be associated with each voxel. Next, the medical imaging device, etc. associates image density information indicating image density in the medical image data acquired in the imaging process with each voxel. Furthermore, the medical imaging device, etc. associates biological property information indicating biological properties acquired in the measurement process with each voxel. As a result, medical 3D data, which is information in which voxels, image density information, and biological property information are associated, can be created as shown in FIG. 3. The medical 3D data can be segmented into voxel regions using image density information. Voxel region segmentation refers to classifying and segmenting voxels with similar image densities. This enables shape recognition, structure division, tissue analysis, and 3D image analysis of the internal structure of a living body based on the medical 3D data, and for example, medical 3D data of a specific tissue such as the liver can be obtained from the medical 3D data of a living body. In the present invention, medical 3D data in a partial region obtained by dividing the medical 3D data into voxel regions as shown in Fig. 4 is referred to as regional medical 3D data. Note that regional medical 3D data is considered to be one concept included in medical 3D data.

(2) Generation Step The modeling method of the present invention preferably includes a generation step of generating 3D modeling data based on medical 3D data. In this disclosure, "3D modeling data" refers to data generated based on medical 3D data and input to a 3D printer. The 3D modeling data may be composed of one piece of data or may be composed of multiple pieces of data. Below, two specific examples of a method for generating 3D modeling data will be described, but the present method is not limited to these.

(I) Generation of 3D Modeling Data Including Data in STL Format A case will be described where 3D modeling data including data in STL (Standard Triangulated Language) format is generated based on medical 3D data.
In this case, as shown in Fig. 5, surface model conversion is performed on the regional medical 3D data obtained by dividing the medical 3D data into voxel regions, and data in the STL format corresponding to the regional medical 3D data is created. Since the STL format data is surface data, the biological property information assigned to each voxel of the regional medical 3D data is lost by performing surface model conversion. Therefore, apart from the surface model conversion, biological property information for 3D printing is created from the regional medical 3D data, including position information indicating the position of the voxel and biological property information assigned to each position information. The biological property information assigned to each position information is biological property information associated with the voxel located at the position indicated by the position information. That is, the 3D data for printing in this description includes data in the STL format and biological property information for 3D printing.

(II) Generation of 3D Modeling Data Including Data in FAV Format A case will be described where 3D modeling data including data in the FAV (Fabricatable Voxel) format is generated based on medical 3D data.
In this case, as shown in Fig. 6, the medical 3D data is divided into voxel regions, and the medical 3D data by region is obtained by performing FAV format conversion to generate FAV format data corresponding to the medical 3D data by region. Note that the FAV format data is defined as voxel data, not as surface data as in the STL format data. This allows the medical 3D data, which is voxel data to which image density information, biological property information, etc. are added, to be converted to FAV format data with the image density information, biological property information, etc. added. In other words, this is preferable in that it can omit a separate data processing process for necessary information such as biological property information, as in the case of conversion to STL format data.

(3) Modeling process The modeling method of the present invention includes a modeling process of modeling a three-dimensional object using a 3D printer based on medical 3D data of a living body. As described above, in this disclosure, "modeling a three-dimensional object using a 3D printer based on medical 3D data of a living body" is not limited to a case where medical 3D data is directly used, such as inputting medical 3D data to a 3D printer to model a three-dimensional object, but also refers to a case where medical 3D data is indirectly used, such as inputting modeling 3D data generated based on medical 3D data to a 3D printer to model a three-dimensional object. Hereinafter, the modeling process will be described using as an example a case where modeling 3D data generated based on medical 3D data is input to a 3D printer to model a three-dimensional object.

First, a case will be described in which 3D modeling data including the above-mentioned STL format data is input to a 3D printer. In this case, the 3D modeling data includes STL format data and biological property information for 3D modeling. These data may be input simultaneously or separately.
The 3D printer converts the input data in the STL format into a 2D image data set for printing. The 2D image data set for printing is a data set including a plurality of 2D image data for printing, and the 2D image data for printing is two-dimensional slice data obtained by slicing the data in the STL format in accordance with the resolution of the 3D printer in the Z-axis direction. Next, the 3D printer imparts strength property information indicating the strength property in each region of the 2D image data for printing based on the input biological property information for 3D printing. Based on the 2D image data for printing and the strength property information in each region of the 2D image data for printing, the 3D printer repeats the process of discharging a plurality of types of modeling compositions in a predetermined amount into each predetermined region and curing them, thereby forming a three-dimensional object having a distribution of strength properties corresponding to the distribution of biological properties. Here, in the present disclosure, the "strength property" represents the property of a three-dimensional object formed by a 3D printer, and specifically, represents viscoelasticity since it is a property corresponding to biological properties.

Next, a case where 3D modeling data including the above-mentioned FAV format data is input to a 3D printer will be described.
The 3D printer converts the input data in the FAV format into a 2D image data set for printing, which is slice data similar to the above. However, each 2D image data set for printing included in the 2D image data set for printing is provided with strength property information indicating the strength property in each region based on the biological property information included in the FAV format data. Based on the 2D image data for printing and the strength property information in each region of the 2D image data for printing, the 3D printer repeats the process of ejecting a plurality of types of modeling compositions in a predetermined ejection amount into each predetermined region and curing them, thereby forming a three-dimensional object having a distribution of strength properties corresponding to the distribution of biological properties.

Examples of 3D printers used in the modeling process include printers that can control the strength properties of the three-dimensional object to be modeled for each part by discharging multiple types of modeling compositions in predetermined amounts onto each predetermined area.Specific examples include material jetting (MJ) type 3D printers that discharge modeling compositions using an inkjet head.

As described above, as a method for using a 3D printer to make the strength properties correspond to the biological properties, a method using a 3D printer capable of expressing the strength properties by gradation can be given. Hereinafter, an example of this method will be described.
First, a high-strength shaping composition capable of forming a three-dimensional object having high strength properties and a low-strength shaping composition capable of forming a three-dimensional object having low strength properties are prepared. At least one type of each of these shaping compositions is used, but multiple types of each may be used. In this case, it is preferable that the strength property of the three-dimensional object formed from the high-strength shaping composition is equal to or greater than the maximum value of the biological property in a living body, and it is preferable that the strength property of the three-dimensional object formed from the low-strength shaping composition is equal to or less than the minimum value of the biological property in a living body.
Next, the strength properties of the three-dimensional object are controlled by the pattern of the molding composition arranged to fill a certain grid area. For example, as shown in FIG. 7, when an expression with seven gradations of strength properties is required, a combination pattern in which a grid with six sections as a minimum unit is filled with a high-strength molding composition and a low-strength molding composition enables the expression of seven gradations of strength. By increasing the number of sections of the unit grid, various gradations can be expressed. By arranging in the XY plane, the planar intensity distribution can be set, and by arranging in the Z direction, the vertical intensity distribution can be set, thereby forming a three-dimensional object having a distribution of strength properties corresponding to the distribution of biological properties. That is, in the present disclosure, the "distribution of strength properties corresponding to the distribution of biological properties" is not limited to the case where the strength properties in the distribution are the same as the biological properties at the corresponding position, but also includes the case where the strength properties realized by the gradation expression are similar to the biological properties at the corresponding position. Examples of the case where they are similar include the case where the difference between the strength properties (synonymous with the model properties described later) and the biological properties is within 5%. In addition, in the present disclosure, "gradation" refers to an arrangement pattern formed by respectively arranging multiple types of molding compositions, as described above, in which the strength properties of the cured product differ for each arrangement pattern.
In addition, since this method can be expressed as voxels, it is efficient to make it compatible with a voxel format such as FAV. Also, the number of droplets of the modeling composition filling the unit section may be any number.
Furthermore, by understanding the intensity properties in the gradations that can be expressed by the 3D printer in advance using MRE measurements, it is possible to more accurately create a three-dimensional object having a distribution of intensity properties that corresponds to the distribution of biological properties.

(4) Evaluation step The modeling method of the present invention may include an evaluation step of evaluating the accuracy of the modeled three-dimensional object. The evaluation step is a step of evaluating the accuracy of the modeled three-dimensional object based on biological property information indicating biological properties acquired by MRE measurement of a living body in the acquisition step (specifically, the measurement step in the acquisition step) and model property information indicating model properties acquired by MRE measurement of the three-dimensional object (model) modeled in the modeling step. This step may be performed by a person or by an information processing device such as a personal computer.

First, a method for evaluating the accuracy of a three-dimensional object formed based on the biological physical property information and the model physical property information will be described.
Methods for evaluating the accuracy of a three-dimensional object include, for example, a method for evaluating the accuracy by determining whether the distribution of biological properties and the distribution of model physical properties are approximately identical, and a method for evaluating the accuracy by determining whether corresponding parts of a living organism and a three-dimensional object have approximately identical biological properties and model physical properties.

Corresponding parts of a living organism and a three-dimensional object include, for example, parts in a living organism and parts in a three-dimensional object that have approximately the same coordinates when coordinates are assigned to the living organism and the three-dimensional object using the same criteria, parts in a living organism that have a specific structure (such as a tumor) and parts in a three-dimensional object that mimic a part in a living organism that has the specific structure (such as a part that mimics a tumor).
An example of a criterion for determining whether corresponding parts of a living organism and a three-dimensional object have substantially identical living organism properties and model properties is that the difference between the model properties and the living organism properties at the corresponding parts is within 5%. Note that the difference is not limited to within 5% and can be appropriately selected depending on the degree of accuracy required, and may be within 50%, 40%, 30%, 20%, 10%, or the like, but it is preferable that the difference is small from the viewpoint of being able to evaluate high accuracy.

As described above, in order to compare the biological property information and the model property information at the corresponding parts of the biological body and the model, it is preferable to also have information indicating the position in the biological body where the biological property was measured and information indicating the position in the three-dimensional object where the model property was measured. Therefore, when evaluating the accuracy of the three-dimensional object, it is preferable to use medical 3D data, which is information in which voxels, image density information, and biological property information are associated, and model 3D data, which is information in which voxels, image density information, and model property information are associated, and compare the biological property information and the model property information contained in these data. This is because voxels correspond to the information indicating the above-mentioned position. Note that the model 3D data is data obtained in the same manner as the medical 3D data, and represents data created based on at least model image data obtained by photographing the three-dimensional object with a medical imaging device and model properties obtained by MRE measurement of the three-dimensional object.

This evaluation process uses model properties obtained by MRE measurement of the three-dimensional object. This means that it is preferable that the material constituting the three-dimensional object contains water as one of the main components, which is suitable for MRE measurement using hydrogen nuclei as a signal source. In other words, it is preferable that the material constituting the three-dimensional object contains a hydrogel as described below.

2. Modeling Composition The modeling composition used in the modeling process will be described. The modeling composition may be any composition that can be used in a 3D printer and can model a three-dimensional object having a distribution of strength properties corresponding to the distribution of biological properties, and examples of such compositions include compositions serving as precursors for modeling elastomers and gels. Among these, a composition serving as a precursor for modeling a hydrogel that contains water, similar to a living body, as one of the main components of the constituent materials (referred to as a "hydrogel three-dimensional modeling composition") is preferred. Hereinafter, a hydrogel three-dimensional modeling composition will be described as an example of a modeling composition.

The hydrogel composition for three-dimensional modeling contains water and a polymerizable compound, and may contain minerals, organic solvents, and other components, as necessary.
In the present disclosure, the term "hydrogel three-dimensional modeling composition" refers to a liquid composition that hardens to form a hydrogel by irradiation with active energy rays such as light or heat, and is particularly used to model a three-dimensional object made of a hydrogel. In addition, in the present disclosure, the term "hydrogel" refers to a structure in which water is contained in a three-dimensional network structure containing a polymer, and when such a three-dimensional network structure is a three-dimensional network structure formed by the composite of a polymer and a mineral, it is particularly called an "organic-inorganic composite hydrogel." Note that the hydrogel contains water as a main component, and specifically, the content of water is preferably 30.0% by mass or more, more preferably 40.0% by mass or more, and even more preferably 50.0% by mass or more, based on the total amount of the hydrogel.

(1) Water The hydrogel three-dimensional modeling composition contains water. The water is not particularly limited as long as it can be used as a solvent in general, and examples of water that can be used include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, and ultrapure water.
The water content can be appropriately selected depending on the purpose; for example, when the hydrogel 3D modeling composition is used to model an organ model, the water content is preferably 30.0% by mass or more and 90.0% by mass or less, and more preferably 40.0% by mass or more and 90.0% by mass or less, relative to the total amount of the hydrogel 3D modeling composition.
In addition, other components such as organic solvents may be dissolved or dispersed in the water depending on the purpose of imparting moisture retention, antibacterial properties, electrical conductivity, adjusting hardness, etc.

(2) Polymerizable Compound The hydrogel three-dimensional modeling composition contains a polymerizable compound, which is a compound having a polymerizable functional group. Examples of the polymerizable compound include monomers and oligomers. The polymerizable compound is polymerized by irradiation with active energy rays or heat to form at least a part of a polymer. That is, the polymer has a structural unit derived from the polymerizable compound. In addition, it is preferable that the polymer is crosslinked with a mineral to form a composite and form a three-dimensional network structure in the hydrogel. Here, it is preferable that the polymerizable compound is water-soluble. Water-soluble means that, for example, when 100 g of water at 30° C. and 1 g of monomer are mixed and stirred, 90% by mass or more of the monomer is dissolved.

The polymerizable compound is not particularly limited as long as it has a polymerizable functional group, but is preferably a compound having a photopolymerizable functional group. In this disclosure, the term "polymerizable functional group" refers to a functional group that undergoes a polymerization reaction when irradiated with active energy rays or when heat is added, and the term "photopolymerizable functional group" refers to a functional group that undergoes a polymerization reaction when irradiated with active energy rays. Examples of photopolymerizable functional groups include, but are not limited to, groups having an ethylenically unsaturated bond such as a (meth)acryloyl group, a vinyl group, or an allyl group, and cyclic ether groups such as an epoxy group. Specific examples of compounds containing a group having an ethylenically unsaturated bond include, for example, a compound having a (meth)acrylamide group, a (meth)acrylate compound, a compound having a (meth)acryloyl group, a compound having a vinyl group, and a compound having an allyl group.

(I) Monomer The monomer that can be used as the polymerizable compound is preferably a compound having one or more polymerizable functional groups such as an unsaturated carbon-carbon bond, and examples thereof include monofunctional monomers and polyfunctional monomers. Furthermore, examples of polyfunctional monomers include bifunctional monomers and trifunctional or higher functional monomers. These may be used alone or in combination of two or more.

(A) Monofunctional Monomer Examples of the monofunctional monomer include acrylamide, N-substituted acrylamide derivatives, N,N-disubstituted acrylamide derivatives, N-substituted methacrylamide derivatives, N,N-disubstituted methacrylamide derivatives, acrylic acid, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, 3-methoxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, lauryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, tridecyl (meth)acrylate, caprolactone (meth)acrylate, and ethoxylated nonylphenol (meth)acrylate. These may be used alone or in combination of two or more. Among these, acrylamide, N,N-dimethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, hydroxyethylacrylamide, isobornyl (meth)acrylate, and the like are preferable.

The content of the monofunctional monomer is preferably 0.5% by mass or more and 30.0% by mass or less based on the total amount of the hydrogel three-dimensional modeling composition.

(B) Bifunctional Monomer Examples of the bifunctional monomer include tripropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol hydroxypivalic acid ester di(meth)acrylate, hydroxypivalic acid neopentyl glycol ester di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. Examples of such acrylates include 1,9-nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol ester di(meth)acrylate, propoxylated dipentyl glycol di(meth)acrylate, ethoxy-modified bisphenol A di(meth)acrylate, polyethylene glycol 200 di(meth)acrylate, and polyethylene glycol 400 di(meth)acrylate. These may be used alone or in combination of two or more.

(C) Trifunctional or higher monomers Examples of trifunctional or higher monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, triallyl isocyanurate, ε-caprolactone-modified dipentaerythritol tri(meth)acrylate, ε-caprolactone-modified dipentaerythritol tetra(meth)acrylate, ε-caprolactone-modified dipentaerythritol penta(meth)acrylate, ε-caprolactone-modified dipentaerythritol hexa(meth)acrylate, tris Examples of such compounds include (2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated glyceryl tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hydroxypenta(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, penta(meth)acrylate ester, etc. These compounds may be used alone or in combination of two or more.

The content of the polyfunctional monomer is preferably 0.01% by mass or more and 10.0% by mass or less based on the total amount of the hydrogel three-dimensional modeling composition.

(II) Oligomer The oligomer is a low polymer of the above-mentioned monofunctional monomer or a low polymer having a reactive unsaturated bond group at the end. These may be used alone or in combination of two or more kinds.

(3) Mineral The hydrogel composition for three-dimensional modeling preferably contains a mineral. The mineral is not particularly limited as long as it is capable of bonding with the polymer formed from the polymerizable compound, and may be appropriately selected depending on the purpose. For example, layered clay minerals, particularly water-swellable layered clay minerals, may be mentioned.
The water-swellable layered clay mineral will be described with reference to FIG. 8. FIG. 8 is a schematic diagram showing an example of a water-swellable layered clay mineral as a mineral and a state in which the water-swellable layered clay mineral is dispersed in water. As shown in the upper diagram of FIG. 8, the water-swellable layered clay mineral exists in a single layer state, and exhibits a state in which two-dimensional disk-shaped crystals having unit lattices within the crystal are stacked. When the water-swellable layered clay mineral in the upper diagram of FIG. 8 is dispersed in water, each single layer separates to form a plurality of two-dimensional disk-shaped crystals, as shown in the lower diagram of FIG. 8.
The term "water-swellable" refers to the property of water molecules being inserted between the individual monolayers of the layered clay mineral and dispersing in water, as shown in Fig. 8. The shape of the monolayer of the water-swellable layered clay mineral is not limited to a disk shape, and may be other shapes.

Examples of water-swellable layered clay minerals include water-swellable smectite and water-swellable mica. More specifically, water-swellable hectorite, water-swellable montmorillonite, water-swellable saponite, water-swellable synthetic mica, and the like, each containing sodium as an interlayer ion, may be used. These may be used alone or in combination of two or more. Among these, water-swellable hectorite is preferred because it can produce a highly elastic hydrogel.
The water-swellable hectorite may be appropriately synthesized or may be a commercially available product. Examples of commercially available products include synthetic hectorite (Laponite XLG, manufactured by Rockwood), SWN (manufactured by Coop Chemical Ltd.), and fluorinated hectorite SWF (manufactured by Coop Chemical Ltd.). Among these, synthetic hectorite is preferred from the viewpoint of improving the elastic modulus of the hydrogel.

The mineral content is preferably 1.0% by mass or more and 40.0% by mass or less based on the total amount of the hydrogel 3D modeling composition.

(4) Organic Solvent The hydrogel three-dimensional modeling composition may contain an organic solvent, if necessary. The organic solvent is contained for the purpose of increasing the moisture retention of the hydrogel, for example.
Examples of the organic solvent include alkyl alcohols having 1 to 4 carbon atoms, amides, ketones, ketone alcohols, ethers, polyhydric alcohols, polyalkylene glycols, lower alcohol ethers of polyhydric alcohols, alkanolamines, N-methyl-2-pyrrolidone, etc. These may be used alone or in combination of two or more.
Among these, polyhydric alcohols are preferred from the viewpoint of moisturizing properties, and specifically, polyhydric alcohols such as ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, and glycerin are preferably used.
The content of the organic solvent is preferably 10.0% by mass or more and 50.0% by mass or less based on the total amount of the hydrogel 3D modeling composition, in which case drying of the hydrogel 3D modeling composition can be suppressed, and dispersibility of the mineral in the hydrogel 3D modeling composition can be improved by setting the content to 50.0% by mass or less.

(5) Other Components The hydrogel three-dimensional modeling composition may contain other components as necessary.
The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples of the other components include stabilizers, surface treatment agents, polymerization initiators, colorants, viscosity modifiers, adhesion promoters, antioxidants, antiaging agents, crosslinking agents, ultraviolet absorbers, plasticizers, preservatives, metal ions, fillers, metal fine particles, and dispersants.

(I) Stabilizer The stabilizer is contained in order to stably disperse the mineral and maintain the sol state of the hydrogel 3D modeling composition. In addition, when the hydrogel 3D modeling composition is used in a method of ejecting the composition as droplets, the stabilizer is contained in order to stabilize the properties of the composition as a liquid.
Stabilizers include, for example, high concentration phosphates, glycols, non-ionic surfactants, and the like.

(II) Surface Treatment Agent Examples of the surface treatment agent include polyester resins, polyvinyl acetate resins, silicone resins, coumarone resins, fatty acid esters, glycerides, and waxes.

(III) Polymerization initiator Examples of the polymerization initiator include a thermal polymerization initiator, a photopolymerization initiator, etc. Among these, from the viewpoint of storage stability, a photopolymerization initiator that generates a radical or a cation by irradiation with an active energy ray is preferred.
As the photopolymerization initiator, any substance that generates radicals when irradiated with light (particularly ultraviolet light having a wavelength of 220 nm or more and 400 nm or less) can be used.
The thermal polymerization initiator is not particularly limited and can be appropriately selected depending on the purpose. Examples of the thermal polymerization initiator include azo-based initiators, peroxide initiators, persulfate initiators, and redox (oxidation-reduction) initiators.

(6) Physical properties of the hydrogel three-dimensional modeling composition The viscosity of the hydrogel three-dimensional modeling composition at 25 ° C. is preferably 3.0 mPa · s or more and 20.0 mPa · s or less, more preferably 6.0 mPa · s or more and 12.0 mPa · s or less. By having a viscosity of 3.0 mPa · s or more and 20.0 mPa · s or less, it can be suitably applied to droplet ejection in a 3D printer (particularly a material jetting method). The viscosity can be measured using, for example, a rotational viscometer (VISCOMATE VM-150III, manufactured by Toki Sangyo Co., Ltd.).

The surface tension of the hydrogel 3D modeling composition is preferably 20 mN/m or more and 45 mN/m or less, and more preferably 25 mN/m or more and 34 mN/m or less. If the surface tension is 20 mN/m or more, the ejection stability can be improved, and if it is 45 mN/m or less, it becomes easier to fill the hydrogel 3D modeling composition into an ejection nozzle for modeling. The surface tension can be measured, for example, using a surface tensiometer (automatic contact angle meter DM-701, manufactured by Kyowa Interface Science Co., Ltd.).

3. Method for Forming a Three-Dimensional Object Using a 3D Printer As an example of a method for forming a three-dimensional object using a 3D printer (hereinafter also referred to as a "modeling device"), a method for forming a hydrogel three-dimensional object using the above-mentioned hydrogel three-dimensional modeling composition with a material jetting type 3D printer will be described.

The method for forming a hydrogel three-dimensional object by the material jetting method includes a liquid film forming step of applying droplets of a hydrogel three-dimensional object composition to form a liquid film, and a curing step of curing the liquid film of the hydrogel three-dimensional object composition, and is characterized in that the liquid film forming step and the curing step are repeated in sequence. Note that the method for forming a hydrogel three-dimensional object may include a support modeling step of modeling a support that supports the hydrogel three-dimensional object and other steps, as necessary.
The device for forming a hydrogel 3D object using a material jetting method comprises a storage means for storing a hydrogel 3D modeling composition, a liquid film forming means for applying droplets of the stored hydrogel 3D modeling composition to form a liquid film, and a hardening means for hardening the liquid film of the hydrogel 3D modeling composition, and is characterized in that the liquid film formation by the liquid film forming means and the hardening by the hardening means are sequentially repeated.

First, the material jetting method will be described with reference to Figures 9 and 10. Figure 9 is a schematic diagram showing an example of a modeling device for a hydrogel three-dimensional object. Figure 10 is a schematic diagram showing an example of peeling off a hydrogel three-dimensional object from a support. The modeling device 10 for a hydrogel three-dimensional object using the material jetting method shown in Figure 9 uses a head unit in which inkjet heads are arranged, and sprays the hydrogel three-dimensional modeling composition contained in a hydrogel three-dimensional modeling composition storage container from the hydrogel three-dimensional modeling composition jetting head unit 11 and the support modeling composition contained in a support modeling composition storage container from the support modeling composition jetting head unit 12 toward a modeling body support substrate 14, and stacks the hydrogel three-dimensional modeling composition and the support modeling composition while curing them with the adjacent ultraviolet irradiator 13. Here, the support modeling composition represents a liquid composition that is cured by irradiation with active energy rays such as light or heat, and forms a support that supports a hydrogel three-dimensional object, and examples of such compositions include acrylic materials. The modeling device 10 may also have a smoothing member 16 that smoothes the sprayed hydrogel three-dimensional modeling composition.

The modeling device 10 stacks the layers while lowering the stage 15 according to the number of layers in order to maintain a constant gap between the hydrogel 3D modeling composition jetting head unit 11, the support modeling composition jetting head unit 12, and the ultraviolet irradiator 13 and the 3D object (hydrogel) 17 and the support (support material) 18.

The ultraviolet irradiator 13 in the modeling device 10 is used when moving in either direction of arrow A or B, and the heat generated by ultraviolet irradiation smoothes the layered surface, resulting in improved dimensional stability of the three-dimensional object 17.

After the modeling in the modeling device 10 is completed, the three-dimensional object 17 and the support 18 are pulled horizontally as shown in FIG. 10, and the support 18 is peeled off as a unit, allowing the three-dimensional object 17 to be easily removed.

(1) Liquid film forming process In the liquid film forming process, the method of applying the hydrogel three-dimensional modeling composition is not particularly limited as long as it is a method that can apply droplets to the target position with appropriate accuracy, and can be appropriately selected depending on the purpose, and a known droplet ejection method can be used. Specific examples of the droplet ejection method include a dispenser method, a spray method, and an inkjet method, and the inkjet method is preferable.

The volume of the droplets of the hydrogel 3D modeling composition is, for example, preferably 2 pL or more and 60 pL or less, and more preferably 15 pL or more and 30 pL or less. If the volume of the droplets is 2 pL or more, the ejection stability can be improved, and if it is 60 pL or less, it becomes easier to fill the hydrogel 3D modeling composition into an ejection nozzle for modeling, etc.

(2) Curing Step In the curing step, the liquid film of the hydrogel three-dimensional modeling composition can be cured by, for example, an ultraviolet (UV) irradiation lamp, an electron beam, etc. Examples of the type of ultraviolet (UV) irradiation lamp include a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, etc.
As a curing means for the hydrogel three-dimensional modeling composition, a UV-LED (Ultra Violet-Light Emitting Diode) is preferably used. The emission wavelength of the LED is not particularly limited, and generally includes 365 nm, 375 nm, 385 nm, 395 nm, 405 nm, etc., but in consideration of the effect of color on the modeled object, it is more advantageous to emit light with a short wavelength so that the absorption of the initiator is increased. In addition, compared with commonly used ultraviolet irradiation lamps (high pressure mercury lamps, ultra-high pressure mercury lamps, metal halide lamps), electron beams, etc., UV-LEDs generate less heat energy during curing, and the thermal damage to the hydrogel is reduced. In particular, since the hydrogel modeled by the hydrogel three-dimensional modeling composition is used in a state containing water, this effect is remarkable.

The method for forming a hydrogel three-dimensional object includes a liquid film forming step of applying droplets of a hydrogel three-dimensional object forming composition to form a liquid film, and a curing step of curing the liquid film of the hydrogel three-dimensional object forming composition, and the liquid film forming step and the curing step are repeated in sequence. At this time, the number of repetitions is not particularly limited and can be appropriately selected depending on the size, shape, etc. of the hydrogel three-dimensional object to be formed. In addition, the average thickness per layer after curing is preferably 10 μm or more and 50 μm or less. By having an average thickness of 10 μm or more and 50 μm or less, it is possible to form the object with high precision and with little peeling.

(3) Support Modeling Process The support modeling composition used in the support modeling process is a liquid composition that hardens when irradiated with active energy rays such as light or heat, and models a support that supports a hydrogel three-dimensional object. The composition for the support modeling composition is different from the composition for hydrogel three-dimensional modeling. Specifically, it preferably contains a hardening material and a polymerization initiator, and does not contain water or minerals. The hardening material is a compound that hardens by polymerization reaction when irradiated with active energy rays (ultraviolet rays, electron beams, etc.), heated, etc., and examples of such compounds include active energy ray-curable compounds and thermosetting compounds. Among these, materials that are liquid at room temperature are preferred.
The support forming composition is applied to a position different from that of the hydrogel 3D modeling composition. This means that the support forming composition and the hydrogel 3D modeling composition do not overlap each other, and the support forming composition and the hydrogel 3D modeling composition may be adjacent to each other.
The method for applying the support modeling composition can be the same as the method for applying the hydrogel three-dimensional modeling composition.

(4) Other steps Examples of other steps include a step of smoothing the liquid film, a peeling step, a polishing step of the three-dimensional object, and a cleaning step of the three-dimensional object, but it is preferable to include a step of smoothing the liquid film. This is because the liquid film formed in the liquid film forming step does not necessarily have a target film thickness (layer thickness) at all positions. For example, when forming a liquid film using an inkjet method, there are cases where non-ejection or steps between dots occur, making it difficult to form a three-dimensional object with high precision. To address these issues, methods such as mechanically smoothing (leveling) the liquid film after it is formed, mechanically scraping off the thin hydrogel film obtained by hardening the liquid film, detecting the smoothness and adjusting the amount of film formation at the dot level when laminating the next layer, etc. are conceivable. Note that when a hydrogel three-dimensional object is formed for an organ model, the hardness of the hydrogel is relatively soft, so that a method of mechanically leveling the liquid film is preferable as a method of smoothing. Examples of mechanically smoothing methods include a method of leveling with a blade-shaped member or a roller-shaped member.

(5) Method for Forming a Hydrogel 3D Object Having Parts with Different Strength Properties Next, as a more specific explanation of the method for forming a hydrogel 3D object, an example of a method for forming a hydrogel 3D object having parts with different strength properties will be described. In the following explanation, a detailed explanation will be given using an example in which two types of hydrogel 3D modeling compositions with different compositions are used, but the present invention is not limited to this example. Those skilled in the art will easily understand other examples (e.g., an example in which three or more types of hydrogel 3D modeling compositions are used) from this explanation.

The method for forming a hydrogel three-dimensional object having regions with different strength properties includes a liquid film formation process in which a liquid film having multiple regions with different compositions is formed by applying droplets of multiple hydrogel three-dimensional modeling compositions each having a different composition, and a hardening process in which the liquid film is hardened, and is characterized by sequentially repeating the liquid film formation process and the hardening process.
The above-mentioned modeling method uses a hydrogel 3D object modeling device that includes a storage means for storing a plurality of hydrogel 3D modeling compositions each having a different composition, a liquid film forming means for forming a liquid film having a plurality of regions having different compositions by applying droplets of each of the stored hydrogel 3D modeling compositions each having a different composition, and a hardening means for hardening the liquid film, and is characterized in that liquid film formation by the liquid film forming means and hardening by the hardening means are repeated in sequence.
Specifically, a first hydrogel 3D modeling composition and a second hydrogel 3D modeling composition having a different composition from the first hydrogel 3D modeling composition are used, and the positions and amounts of droplets of each hydrogel 3D modeling composition are controlled to form a liquid film having a continuous plurality of regions with different compositions. The first hydrogel 3D modeling composition is an example of the high-strength modeling composition, and the second hydrogel 3D modeling composition is an example of the low-strength modeling composition. Next, the liquid film is hardened to form one layer of a cured film having the continuous plurality of regions. Then, the liquid film is formed and cured by sequentially repeating the formation and curing of the liquid film to stack the cured films, thereby forming a hydrogel 3D object having a continuous plurality of regions with different strength properties. The multiple regions with different strength properties in the hydrogel 3D object may be present due to the difference in strength properties within one layer of the cured film, or may be present due to the difference in strength properties between the cured films.

4. Uses of the Three-dimensional Object Uses of the three-dimensional object include, for example, tissue models imitating tissues of a living body, and preferably human tissue models. Here, tissue refers to functional organs that constitute a living body. Therefore, tissue is not limited to internal organs, but includes all organs that constitute a living body, such as bones, skin, and blood vessels. Moreover, the tissue model is preferably an organ model.
The uses of organ models can be broadly divided into two categories. One is an organ model for general-purpose use, and the other is an organ model for individual use. The organ model for general-purpose use is, for example, an organ model used for performance confirmation in medical device development, calibration, training, structural confirmation in educational settings, and the like. In this case, the organ model has the average shape and physical properties of the target organ. In addition, in this case, the organ model is preferably a model that is mainly modeled based on data of healthy individuals, and data of a single or multiple individuals is averaged. In this case, the organ model for individual use is, for example, an organ model used for informed consent, preoperative simulation, surgical training, and the like in medical settings. In this case, the organ model has the shape and physical properties of the organ including the affected area of the target individual patient. In addition, in this case, the organ model is preferably a model that is modeled based on data of an individual patient, and the affected area is reproduced.
When the three-dimensional object is used as a human organ model, the water content in the material such as hydrogel forming the three-dimensional object is preferably 70% by mass or more and 85% by mass or less with respect to the total amount of the three-dimensional object. By being 70% by mass or more and 85% by mass or less, the water content of the human organ model can be made equivalent to that of the actual human organ that is the subject of the human organ model, and the human organ model can be used preferably. Specifically, the water content is preferably about 80% by mass for a human heart model, about 83% by mass for a human kidney model, and about 75% by mass for a human brain or intestine model. Therefore, the water content of the three-dimensional object is more preferably 75% by mass or more and 83% by mass or less with respect to the total amount of the three-dimensional object.

The following describes examples of the present invention, but the present invention is not limited to these examples.

<Preparation of high-strength molding composition A>
First, degassing was performed on ion-exchanged water under reduced pressure for 30 minutes to prepare pure water, and 67.0 parts by mass of synthetic hectorite (Laponite RD, manufactured by BYK Corporation), which is a water-swellable clay mineral, was gradually added to 580.0 parts by mass of this pure water while stirring, and further stirred to prepare a mixed liquid. Next, 5.0 parts by mass of etidronic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the mixed liquid as a dispersant for synthetic hectorite to obtain a dispersion liquid.
Next, 262.0 parts by mass of dimethylacrylamide (DMAA, manufactured by Tokyo Chemical Industry Co., Ltd.) from which polymerization inhibitors had been removed by passing through an activated alumina column was added as a monomer to the obtained dispersion. In addition, 2.4 parts by mass of N,N'-methylenebisacrylamide (MBAA, manufactured by Tokyo Chemical Industry Co., Ltd.) and 8.0 parts by mass of polyethylene glycol diacrylate (A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) were added as crosslinking agents. Furthermore, 300.0 parts by mass of glycerin (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) were added as a drying inhibitor and mixed.
Next, 6.7 parts by mass of N,N,N',N'-tetramethylethylenediamine (TEMED, manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a polymerization accelerator, and 5.3 parts by mass of Emulgen LS-106 (manufactured by Kao Corporation) was added as a surfactant and mixed.
Next, while cooling in an ice bath, 12.3 parts by mass of a 4% by mass solution of a photopolymerization initiator (Irgacure 184, manufactured by BASF) in methanol was added, and after stirring and mixing, degassing under reduced pressure was performed for 20 minutes. Then, filtration was performed to remove impurities, and a homogeneous high-strength molding composition A was obtained.

-Measurement of viscoelasticity in the cured product of high-strength molding composition A-
First, a hydrogel was produced using the high-strength modeling composition A. Specifically, a container measuring 31 mm × 31 mm (thickness 10 mm) was prepared, the inside of which was filled with the high-strength modeling composition A, and the composition was cured using an ultraviolet irradiator (SPOT CURE SP5-250DB, manufactured by Ushio Inc.). The irradiation conditions were wavelength: 365 nm, irradiation intensity: 350 mJ/cm ² , and irradiation time: 60 seconds.
Next, the physical properties of the produced hydrogel were measured using a rheometer, and were found to be storage modulus: 8,320 Pa, and loss modulus: 2,540 Pa.

<Preparation of low-strength molding composition B>
First, degassing was performed on ion-exchanged water under reduced pressure for 30 minutes to prepare pure water, and 67.0 parts by mass of synthetic hectorite (Laponite RD, manufactured by BYK Corporation), which is a water-swellable clay mineral, was gradually added to 580.0 parts by mass of this pure water while stirring, and further stirred to prepare a mixed liquid. Next, 5.0 parts by mass of etidronic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the mixed liquid as a dispersant for synthetic hectorite to obtain a dispersion liquid.
Next, 262.0 parts by mass of dimethylacrylamide (DMAA, manufactured by Tokyo Chemical Industry Co., Ltd.) from which polymerization inhibitors had been removed by passing through an activated alumina column was added as a monomer to the obtained dispersion. In addition, 0.6 parts by mass of N,N'-methylenebisacrylamide (MBAA, manufactured by Tokyo Chemical Industry Co., Ltd.) and 2.0 parts by mass of polyethylene glycol diacrylate (A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) were added as crosslinking agents. Furthermore, 300.0 parts by mass of glycerin (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) were added as a drying inhibitor and mixed.
Next, 6.7 parts by mass of N,N,N',N'-tetramethylethylenediamine (TEMED, manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a polymerization accelerator, and 5.3 parts by mass of Emulgen LS-106 (manufactured by Kao Corporation) was added as a surfactant and mixed.
Next, while cooling in an ice bath, 12.3 parts by mass of a 4% by mass solution of a photopolymerization initiator (Irgacure 184, manufactured by BASF) in methanol was added, and after stirring and mixing, degassing under reduced pressure was performed for 20 minutes. Then, filtration was performed to remove impurities, and a homogeneous low-strength molding composition B was obtained.

-Measurement of viscoelasticity in the cured product of low-strength molding composition B-
First, a hydrogel was produced using the low-strength modeling composition B. Specifically, a container measuring 31 mm × 31 mm (10 mm thick) was prepared, filled with the low-strength modeling composition B, and cured using an ultraviolet irradiator (SPOT CURE SP5-250DB, manufactured by Ushio Inc.). The irradiation conditions were wavelength: 365 nm, irradiation intensity: 350 mJ/cm ² , and irradiation time: 60 seconds.
Next, the physical properties of the produced hydrogel were measured using a rheometer, and were found to be storage modulus: 4,415 Pa, and loss modulus: 3,104 Pa.

<Acquisition of medical 3D data>
Using an MRI device capable of MRE measurement, medical 3D data including the liver portion of a patient suffering from fatty liver was obtained. This medical 3D data was created based on medical image data obtained by photographing the patient with an MRI device and biological properties obtained by MRE measurement of the patient. Specifically, this medical 3D data included a plurality of voxels created based on the medical image data, image density information indicating the image density (MRI signal value) in the medical image data assigned to each voxel, and biological property information indicating the biological property (viscoelasticity) assigned to each voxel.
Furthermore, the biological properties (viscoelasticity) of the liver obtained by MRE measurement were within the range between the viscoelasticity of the hardened material of high-strength modeling composition A and the viscoelasticity of the hardened material of low-strength modeling composition B in all areas.

<Generation of 3D data for modeling>
First, the medical 3D data was divided into voxel regions to obtain regional medical 3D data showing the liver. Next, the regional medical 3D data was converted into an FAV format to generate FAV format data, which is 3D data for modeling.

<Example of liver model>
The high-strength modeling composition A and the low-strength modeling composition B were each placed in a 3D printer that uses a material jetting method and can express gradations of strength properties as shown in Fig. 9, and the inkjet head of the 3D printer was filled with the material jetting method. Next, 3D modeling data was input to the 3D printer, and a liver model, which is a three-dimensional model having a distribution of strength properties corresponding to the distribution of biological properties, was modeled based on the 3D modeling data. Specifically, each modeling composition was sprayed from the inkjet head, and the liquid film formation and hardening were repeated in sequence to model the liver model.

REFERENCE SIGNS LIST 10 Modeling device 11 Hydrogel three-dimensional modeling composition jetting head unit 12 Support body modeling composition jetting head unit 13 Ultraviolet irradiator 14 Modeling body support substrate 15 Stage 16 Smoothing member 17 Three-dimensional model (hydrogel)
18 Support (support material)

JP 2015-069054 A

Claims (4)

A modeling method including a modeling step of modeling an organ model using a 3D printer based on medical 3D data of a living body,
The medical 3D data is created based on medical image data acquired by photographing the living body with a medical image photographing device and biological properties acquired by measuring the living body by MRE,
the organ model has a distribution of intensity properties corresponding to the distribution of the biological properties,
The organ model contains a hydrogel as a material constituting the organ model,
A step of evaluating a difference between the physical properties of the organ model obtained by subjecting the shaped organ model to MRE measurement and the physical properties of the living body,
A molding method comprising: The modeling method according to claim 1, wherein the medical 3D data includes a plurality of voxels created based on the medical image data, image density information indicating the image density in the medical image data assigned to each voxel, and biological property information indicating the biological property assigned to each voxel. The modeling method according to claim 1 or 2, wherein the 3D printer is a material jetting type. The modeling method according to claim 1 , wherein the biological property and the strength property are viscoelasticity.