JP6457785B2 - Biological texture model production method and biological texture model production program - Google Patents

Description

  The present invention is based on medical image diagnostic apparatuses such as X-ray CT (Computed Tomography), MRI (Magnetic Resonance Imaging), and ultrasonic diagnostic apparatus (echo), and optical system image apparatuses (such as an optical microscope and an optical soft texture analyzer). The present invention relates to a technique for producing a three-dimensional living body texture model using the obtained cross-sectional image.

  The need for 3D visualization of affected areas and specific parts of the body in the medical field is increasing in the fields of informed consent, decision on medical policy, medical education, and medical research. In particular, in the case of three-dimensional visualization using a three-dimensional modeling model, a lot of information that cannot be communicated by a computer image can be conveyed by actually touching and viewing a three-dimensional shape as well as vision.

Conventionally, using DICOM (Digital Imaging and Communications in Medicine), which is a standard for medical diagnostic imaging equipment such as X-ray CT and MRI, three-dimensional shape data is produced, and based on that, powder lamination molding It is known that a high-speed and high-precision medical three-dimensional modeling model is produced from a gypsum-based material by a machine.
However, there has been a problem that it is impossible to simulate the softness of complex organs such as the liver having an internal structure and to provide touch information on organs to doctors and nurses who handle the organs.

  On the other hand, there is known a three-dimensional printer capable of producing a three-dimensional modeling model using a resin having different mechanical properties by combining a hard resin and a flexible resin by simultaneous injection of a plurality of resins. Using such a three-dimensional printer, not only the surface but also its internal structure can be reproduced with respect to its shape structure. However, few can reproduce the flexibility of complex organs such as the liver having an internal structure or the hardness of bones.

  In the prior art, a plurality of types of model materials are held and fixed at each modeling position on a holding sheet that can hold the model material for modeling in the net structure, and the next is placed on the fixed model material. A layer holding sheet is placed, and a plurality of types of model materials of the next layer are held and fixed at the respective molding positions on the holding sheet of the next layer, and the model material is sequentially fixed on the upper layer repeatedly. There is a method for producing a three-dimensional structure that can form a three-dimensional object with a multi-color / multi-material structure with different hardness depending on the part by dissolving and removing the holding sheet after laminating layers (Patent Literature) 1). However, in the method of Patent Document 1, if the hardness varies depending on the part, it is necessary to prepare a hard or soft model material corresponding to the hardness of the part.

  In addition, it is a 3D solid model that represents the external structure and external colors of solid objects and the internal structures and internal colors that cannot be observed from the outside, and is a soft material that can observe the internal structure and internal colors by opening them. A produced three-dimensional solid model is known (see Patent Document 2). Although the technique disclosed in Patent Document 2 represents an internal structure and an internal color that cannot be observed from the outside, it does not reproduce the mechanical characteristics.

  Further, image processing means for extracting data of a target part from tomographic image data photographed by the medical image diagnostic apparatus, image processing means for generating three-dimensional image data from the extracted tomographic image data, and the generated 3 Image processing means for converting dimensional image data to tomographic image data for modeling, means for producing a precision powder model by laminating powder using tomographic data for model building, and transparent using the prepared precision powder model as a mold Alternatively, there is known a method for producing an individually corresponding three-dimensional model of blood vessels and organs made of a flexible polymer such as translucent silicon (see Patent Document 3). The technique disclosed in Patent Document 3 uses tomographic image data captured by a medical image diagnostic apparatus for creating a template, and does not reproduce the texture of a model based on tomographic image data. .

Table 2005/037529 JP 2005-148578 A JP 2003-241647 A

The purpose of the conventional three-dimensional modeling model has been focused on shape confirmation. A high-precision modeling model that can reproduce even smooth shapes and fine parts is what product designers and product designers demand, but it is difficult to imagine the tactile sensation and usability from the shape alone. There is a demand for a modeling model that approximates not only the shape but also the actual touch, feel, and texture.
In addition, the texture of the model depends on the sense of the doctor, and is not based on qualitative data, but there is a demand for a model that has mechanical characteristics close to that of a living body and can be used for a mechanical test of an implant that is implanted in the living body.

  In view of the above situation, the present invention provides a CT value or luminance value of 2 for cross-sectional images of medical image diagnostic apparatuses such as CT, MRI, and echo, and optical system image apparatuses (such as an optical microscope and an optical soft texture analyzer). An object of the present invention is to provide a method for producing a living body texture model that can reproduce not only the feel of living organs possessed by specialists such as doctors but also mechanical characteristics close to the living body from the dimension distribution data.

In order to solve the above problems, the living body texture model manufacturing method of the present invention includes at least the following steps 1) to 5), and reproduces mechanical characteristics close to those of a living body.
1) Two-dimensional distribution data of CT values is acquired from a cross-sectional image obtained by a medical image diagnostic apparatus.
In the present invention, two-dimensional CT values or luminance values are obtained from cross-sectional images of medical image diagnostic apparatuses such as CT, MRI, and echo, and medical image diagnostic apparatuses of optical system image apparatuses (such as an optical microscope and an optical soft texture analyzer). Obtain distribution data. Since MRI images have higher resolution of soft tissues than CT images, it is possible to acquire physical properties of many tissues.
2) Minimum basic units having different hardnesses are prepared in stages, and mechanical characteristic data of at least the hardness, Young's modulus, and fracture modulus of each minimum basic unit is acquired.
Here, the minimum basic unit is a geometrical basic shape such as tetrahedron, hexahedron, cylinder, elliptical column, polygonal column, sphere, wedge shape, pyramid, cone, etc. It has a primitive shape of applied shape. Adjust the type and size of the primitive shape, the number and amount to mix, how to mix, and the resin material to be used to create the desired living body texture by adjusting the softness. Then, each mechanical characteristic data is measured and made into a database for the smallest basic unit having different hardnesses in stages. As the mechanical property data, at least hardness, Young's modulus, and fracture coefficient may be used. Since the elastic modulus can be estimated using MRI elastography or echo, the elastic modulus may be added to the mechanical property data.

3) The bone tissue is estimated from the two-dimensional distribution data of the CT value to discriminate the bone tissue region.
A bone tissue region in which the bone tissue is estimated from the CT value is determined. A soft tissue region other than a bone tissue and an adipose tissue region are also determined as necessary.
4) Obtain the bone density from the CT value of each pixel in the bone tissue region, estimate at least the hardness, Young's modulus and fracture coefficient mechanical property data of each pixel from the bone density, and have the same or the most approximate mechanical property data A minimum basic unit is assigned to each pixel.
Since the bone density can be calculated from the CT value, the bone density is obtained from the CT value of each pixel in the bone tissue region. Then, the mechanical characteristic data of at least the hardness, Young's modulus, and rupture coefficient in each pixel is estimated from the bone density. The minimum basic unit having the same or the most approximate mechanical characteristic data is assigned to each pixel in comparison with the mechanical characteristic data of the minimum basic unit having different degrees of hardness in a stepwise manner that is stored in the database in 2).
5) Laminate cross-sectional images to form three-dimensional data, and form the image with a three-dimensional printer using the minimum basic unit assigned to each pixel.

  In addition, the living body texture model manufacturing method of the present invention is formed using a modeling model manufactured by the above manufacturing method and a material having mechanical property data that is the same as or closest to the mechanical property of the target tissue. This is done by assembling a three-dimensional model in combination with a molding model.

  According to the present invention, a model (bone, organ, etc.) having mechanical characteristics close to that of a living body can be produced. In addition, for an implant used in a living body, it is necessary to obtain a predetermined approval. However, if a model is produced using the present invention and an experiment is performed, it is easy to prepare data for obtaining the approval. Furthermore, a model can be created using the present invention and can be utilized for realistic preoperative training and medical education. In other words, in pre-operative training and education, the model can be used as a hand to understand the three-dimensional structure and feel of living organs, to experience the feel in a simulated manner, and can be used effectively for training of the technique.

Flow chart of living body texture model production method of embodiment 1 (1) Explanatory drawing which calculates the mechanical characteristic value of a specific part from CT image Flow chart of living body texture model production method of embodiment 1 (2) Explanatory drawing of how to create a biological texture model Block diagram of a computer for creating a biological texture model Flow chart of living body texture model preparation method of embodiment 2

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The scope of the present invention is not limited to the following examples and illustrated examples, and many changes and modifications can be made.

FIG. 1 shows a flow of the biological texture model production method of the first embodiment. Hereinafter, the steps will be described step by step.
<Step 1 (S01)>
Two-dimensional distribution data of CT values is acquired from a cross-sectional image obtained by the medical image diagnostic apparatus. The acquired two-dimensional distribution data is stored in a computer memory.
<Step 2 (S02)>
Minimum basic units having different hardnesses are prepared in advance, and mechanical property data of each minimum basic unit is acquired. The mechanical characteristic data of each minimum basic unit is stored in a computer memory. The minimum essential unit (MEU, or cell) has a primitive shape such as a cylinder, cone, or sphere, and is a mixture of one or more of a wide variety of resins. The mechanical property data values are known by actual measurement.

<Step 3 (S03)>
A bone tissue is estimated from the two-dimensional distribution data of CT values to discriminate a bone tissue region. Table 1 shows CT values of human tissues. It is possible to determine the bone tissue region based on the CT value.

<Step 4 (S04)>
The bone density is calculated from the CT value of each pixel in the bone tissue region. Various studies have already been made to calculate bone CT values from CT images and evaluate bone density. It is also known that a test object can be set in an X-ray CT apparatus, photographed on an imaging plate that is a high-sensitivity radiation energy sensor, and subjected to image analysis using a computer to calculate bone density.
<Step 5 (S05)>
The mechanical characteristic data in each pixel is estimated from the calculated bone density.
<Step 6 (S06)>
A minimum basic unit having the same or the most approximate mechanical characteristic data is assigned to each pixel. The approximation of the mechanical property data means that the hardness and elastic modulus are within a predetermined difference.

<Step 7 (S07)>
Cross-sectional images are stacked to form three-dimensional data, and a biological texture model is formed by a three-dimensional printer using the minimum basic unit assigned to each pixel. Note that the three-dimensional shape of the modeling pair is extracted from the luminance information of the two-dimensional data of the medical image diagnostic apparatus. That is, tomographic image dot information including luminance information in DICOM format is obtained from a CT or MRI apparatus, which is a medical image diagnostic apparatus, and the three-dimensional shape of a living body part to be modeled is extracted by stacking these tomographic images. And a 3D modeling model is produced using a commercially available 3D printer.

Next, with reference to FIG. 2, a method for calculating the mechanical characteristic value of the specific part from the CT image will be described. In a cross-sectional image acquired by CT or MRI apparatus, a CT value is obtained for each pixel. A CT value is assigned to each pixel of the matrix. If the tissue is a bone region, the bone density can be calculated, and the mechanical characteristics of the tissue can be estimated from the bone density.
Even if the tissue is a tissue other than the bone region, such as fat, skin, organ, etc., the tissue can be estimated from the CT value. In advance, CT values and mechanical property data of tissues such as fat, skin, and organs are actually measured from a fresh specimen, and the CT values and mechanical properties of the tissues are stored in a database.
On the other hand, minimum basic units (cells) having different hardness in stages are prepared in advance, and mechanical characteristic data of each cell is measured.
Thereby, the tissue is discriminated from the CT value of the cross-sectional image, and a cell having a mechanical characteristic that is the same as or similar to the mechanical characteristic of the discriminated tissue is determined. It becomes possible to prepare a matrix.

  As shown in FIG. 3, a cross-sectional image is acquired from a CT or MRI apparatus (S21), a CT value for each pixel of the acquired image is acquired (S22), bone density is calculated from the CT value, and mechanical characteristics are estimated. (S23). Then, the cell numbers stored in the database are stored. Referring to the table, the cell No. having the same or similar characteristics as the estimated mechanical characteristics. Is selected (S24). For each pixel in the cross-sectional image, cell No. (S25). It repeats with respect to all the acquired cross-sectional images (S26), a cross-sectional image is laminated | stacked, it is made three-dimensional shape, and it models with a 3D printer (S27).

  As shown in FIG. 4, a minimum essential unit (MEU or cell) is specified, and cells having different hardnesses are produced in stages to obtain mechanical characteristics. On the other hand, the elastic modulus is measured using a fresh donation, for example, a CT value (Hounsfield value), MRI elastography, or an ultrasonic diagnostic apparatus (echo), and the mechanical characteristics of the corresponding tissue are acquired. By associating the cell with the image data based on the mechanical property data, it is possible to create a biological texture model having the biological properties of the biological body.

FIG. 5 shows a block diagram of a computer for producing a biological texture model. As shown in FIG. 4, the biological texture model creation computer is a general computer including a CPU, a memory, a screen display unit, an operation input unit, an HDD, and a communication I / F. Specifically, the operation input unit is a touch panel, and the screen display unit is a liquid crystal display. The memory stores data and includes two-dimensional distribution data of CT values, dynamic characteristic data of CT values, and dynamic characteristic data of cells.
The biological texture model creation program is read from the HDD onto the memory and executed by the computer.

FIG. 6 shows a flow of the biological texture model production method of the second embodiment.
In the biological texture model preparation method of the second embodiment, a molded model formed using a material having mechanical property data that is the same as or closest to the mechanical characteristics of the target tissue, and the biological texture model preparation method of the first embodiment. A three-dimensional model is assembled by combining the modeling models produced using the.
As shown in FIG. 6, a cross-sectional image of the target tissue is acquired (S31), and each tissue region such as bone tissue, soft tissue, adipose tissue is discriminated from the two-dimensional distribution data of CT values of the cross-sectional image (S32). ). Like the living body texture model creation method of the first embodiment, the cell table is referred to, a cell having the same or similar mechanical characteristics as estimated from the CT value is selected (S33), and the model is created by 3D modeling (S34). In some cases, a realistic feel can be reproduced. However, depending on the structure, there is a structure in which 3D modeling is difficult or a known material can reproduce a realistic feel. Therefore, in the case of such a structure, the material table is referred to, a material that is the same as or similar to the mechanical property estimated from the CT value is selected (S35), and a model is created by molding (S36), and 3D modeling is performed. The living body pseudo-tissue is assembled by combining the model manufactured in (1) and the model manufactured by molding (S37).
As a result, even if it is difficult to produce all tissues that reproduce a realistic feel in 3D modeling, a biological pseudo-tissue that reproduces a realistic feel can be obtained by complementing a model produced by conventional molding. Can be made.

  The living body texture model produced by the present invention is useful as a material for realistic preoperative training, anatomy and external science.

Claims (8)

1) obtaining two-dimensional distribution data of CT values or luminance values from a cross-sectional image obtained by a medical image diagnostic apparatus or an optical system image apparatus;
2) A step of preparing minimum basic units having different hardnesses step by step and obtaining mechanical property data of at least the hardness, Young's modulus, and fracture modulus of each minimum basic unit;
3) estimating a bone tissue from the two-dimensional distribution data of the CT value and discriminating a bone tissue region;
4) Obtain the bone density from the CT value of each pixel in the bone tissue region, estimate at least the hardness, Young's modulus and fracture coefficient mechanical property data of each pixel from the bone density, and have the same or the most approximate mechanical property data Assigning the minimum basic unit to each pixel;
5) Laminating the cross-sectional images to form three-dimensional data, and shaping with a three-dimensional printer using the minimum basic unit assigned to each pixel;
A biological texture model production method characterized by comprising: Discriminating a soft tissue region and a fat tissue region other than a bone tissue from the two-dimensional distribution data of the CT value or the luminance value;
Estimating at least the hardness, Young's modulus and fracture modulus mechanical property data in each pixel of the soft tissue region and adipose tissue region, and assigning the minimum basic unit having the same or the most approximate mechanical property data to each pixel;
The living body texture model manufacturing method according to claim 1, further comprising: The minimum basic unit has one or more primitive shapes selected from a tetrahedron, a hexahedron, a cylinder, and a sphere,
The living body texture model manufacturing method according to claim 1 or 2, comprising at least one kind of resin material. Molding with a material having mechanical property data that is the same as or closest to the mechanical properties of the target tissue;
Assembling a three-dimensional model by combining the molding model molded by the molding step and the modeling model manufactured by using the manufacturing method according to any one of claims 1 to 3;
A biological texture model production method characterized by comprising: On the computer,
1) a procedure for inputting two-dimensional distribution data of CT values or luminance values from a cross-sectional image obtained by a medical image diagnostic apparatus or an optical system image apparatus;
2) a procedure for inputting mechanical property data of at least the hardness, Young's modulus, and fracture modulus of each of the minimum basic units having different hardness in stages;
3) A procedure for estimating a bone tissue from the two-dimensional distribution data of the CT value and discriminating a bone tissue region;
4) a procedure for calculating the bone density from the CT value of each pixel in the bone tissue region;
5) A procedure for estimating at least the hardness, Young's modulus, and mechanical property data of the fracture coefficient in each pixel from the bone density;
6) a procedure for assigning to each pixel the minimum basic unit having the same or the most approximate mechanical property data;
7) Laminating the cross-sectional images into three-dimensional data, and outputting the information of the minimum basic unit assigned to each pixel to a three-dimensional printer;
Living body texture model creation program for executing Before the procedure of 7) above,
A procedure for discriminating a soft tissue region and a fat tissue region other than bone tissue from the two-dimensional distribution data of the CT value or luminance value;
Estimating at least the hardness, Young's modulus, and fracture coefficient mechanical property data in each pixel of the soft tissue region and the fat tissue region, and assigning the minimum basic unit having the same or the most approximate mechanical property data to each pixel;
The biological texture model production program of Claim 5 for performing. The minimum basic unit has one or more primitive shapes selected from a tetrahedron, a hexahedron, a cylinder, and a sphere,
The biological texture model production program according to claim 5 or 6 , wherein the biological texture model production program is made of at least one kind of resin material. A molding model formed using a material having mechanical property data that is the same as or closest to the mechanical property of the target tissue is combined with a modeling model produced using the production program according to claim 5. A biological texture model preparation method characterized by assembling a three-dimensional model.