WO2011007806A1

WO2011007806A1 - Prosthetic bone model, method for forming a prosthetic bone, and simulation system for medical use

Info

Publication number: WO2011007806A1
Application number: PCT/JP2010/061908
Authority: WO
Inventors: 村瀬剛; 五島誠; 中尾良二
Original assignee: Murase Tsuyoshi; Goto Makoto; Nakao Ryoji
Priority date: 2009-07-15
Filing date: 2010-07-14
Publication date: 2011-01-20
Also published as: JP5410525B2; JPWO2011007806A1

Abstract

Provided are a prosthetic bone model optimal for use in an osteotomy, a method that can form a prosthetic bone easily and with high precision, and a simulation system for medical use. The simulation system (20) sets p vertices (A(n)) and q vertices (B(m)) on the peripheries of the cut surfaces (a and b) of bone fragments (A and B) formed by cutting and separating a pre-correction bone model, which represents a bone to be corrected, at a prescribed cut location. The simulation system then derives the distances between vertices (A(n) and B(m)). From minimal distance data (LAmin(n, m) and LBmin(n, m)) derived for all vertices (A(n) and B(m)), the maxima are selected as A-side maximal distance data (LAmax(n, m)) and B-side maximal distance data (LBmax(n, m)). The vertices (A(n) and B(m)) that constitute the larger of these are used as start points, and STL construction lines that constitute STL data are formed.

Description

Artificial bone model for compensation, method for forming artificial bone for compensation, and medical simulation system

The present invention cuts and separates a bone deformed into an abnormal mode, and corrects the normal positional relationship by changing the positional relationship of the separated bone fragment, so that the compensation is arranged between the separated bone fragments. The present invention relates to a method for forming an artificial bone model, a medical simulation system, and a method for forming a replacement artificial bone.
The present invention also relates to a medical three-dimensional image acquisition method for acquiring a three-dimensional image of a desired part, and a medical simulation system using the three-dimensional image acquisition method.

Conventionally, a treatment called osteotomy has been performed to correct a bone deformed into an abnormal form. Traditionally, osteotomy is performed by cutting and separating deformed bones at locations determined based on doctors' empirical rules, and artificial bones created separately between the separated bone fragments. Was carried out by embedding. Therefore, in the prior art, it cannot be said that osteotomy is performed in an ideal state, and there is a problem that the success or failure of the operation may be influenced by the doctor's rule of thumb. In view of such problems, the present inventors have developed a method, member, system, and program for bone correction as disclosed in Patent Document 1 below.

JP 2006-519636 A

According to the method disclosed in the above-mentioned Patent Document 1, it is possible to specify a bone cutting position (cutting surface) and to separate the cut bone pieces (deformation amount) without using a doctor's empirical rule in advance before the treatment. It became possible to hit the treatment. With the provision of the method disclosed in Patent Document 1, an artificial bone model for filling between bone fragments cut and separated in a planning stage before surgery, and an artificial bone for replacement easily and accurately. It has become desirable to provide a method that can be formed.

Also, in the conventional medical image processing technology, DICOM (Digital Imaging and Communication Communication in Medical) data related to CT images obtained by X-ray CT (Computed Tomography) or the like to create a bone surface model is converted into a three-dimensional image. When doing so, enormous man-hours are required to calculate the boundary of the bone surface, and volume data must be used in a preoperative simulation system or the like. As a result, in the conventional simulation system, it takes a lot of time and labor to perform a simulation with movement and to create a preoperative planning, and the simulation system itself is impractical. In addition, in order to utilize volume data, experienced doctors and specialized operators are required, and it is essential to use a computer with excellent information processing ability.

Accordingly, in order to meet such demands, the present invention provides an artificial bone model for supplementation that is optimal for use in osteotomy, a formation method that can easily and accurately form an artificial bone for supplementation, and an osteotomy technique. The purpose was to provide a medical simulation system that could be used for pre-planning. In addition to this, the present invention requires less information processing capability than when using a conventional medical image processing technique, and can easily and accurately form a three-dimensional image of a desired part. An object is to provide a medical three-dimensional image acquisition method and a medical simulation system using the three-dimensional image acquisition method.

The method for forming an artificial bone model for compensation of the present invention provided to solve the above-described problems includes a pre-correction bone model acquisition step, a cutting plane derivation step, a vertex setting step, and a minimum distance data group construction step. And a maximum distance selection step, a start point selection step, and an STL data construction step. In the present invention, the pre-correction bone model acquisition step is a step of acquiring a bone model representing the bone to be corrected as a pre-correction bone model, and the cutting plane derivation step is formed by cutting and separating the pre-correction bone model. This is a step of deriving the cut surfaces a and b related to the bone fragments A and B. The vertex setting step is a step of setting p vertices A (n) on the outer periphery of the cut surface a and setting q apexes B (m) on the outer periphery of the cut surface b. In the minimum distance data group construction step, a distance LA (n, m) between one point constituting p vertices A (n) and a part or all of each vertex B (m) is determined as each vertex B (m). The minimum distance derivation operation A for each of the p vertices A (n) is performed for each of the p vertices A (n), and the minimum distance derivation operation A is selected from the derived distances LA (n, m) and selected as the minimum distance data LAmin (n, m). This is a process for constructing a minimum distance data group by performing a part or all of them. The starting point selecting step is a step of selecting the maximum one of all or part of the data constituting the minimum distance data group. The STL data construction step starts the vertices A (n) and B (m) forming the longest distance L (n, m) included in the distance data group derived in the distance data group construction step, respectively. Select as A (n), B (m), and between the vertices A (n), B (m) aligned in the circumferential direction of the cutting planes a, b with the start points A (n), B (m) as the starting points Are sequentially connected by line segments to construct STL data that expresses the outer surface of the artificial bone to be compensated between the cut surfaces a and b by a plurality of triangle groups.

In the method for forming the artificial bone model for compensation of the present invention, the vertex adjacent to the vertex A (n) in the circumferential direction of the cutting plane a is set as the vertex A (n + 1), and the cutting plane b is applied to the vertex B (m). When the vertex adjacent in the circumferential direction is the vertex B (m + 1), the line connecting the vertices A (n) and B (m + 1) and the line connecting the vertices A (n + 1) and B (m) Of these, it is desirable that a line segment having a short distance is selected as a line segment constituting the STL data.

In the minimum distance data group construction step described above, in addition to the minimum distance derivation operation A, the distance LB () between one point constituting q vertices B (m) and a part or all of each vertex A (n). n, m) is derived for each vertex B (m), and the minimum distance deriving operation B is selected as the minimum distance LBmin (n, m) by selecting the smallest one from the derived distances LB (n, m). This is performed for some or all of the q vertices B (m), and the minimum distance data group is constructed to include the minimum distance data LAmin (n, m) and the minimum distance data LBmin (n, m). Is desirable. In the above-described maximum distance selection step, a part of or all of the minimum distance data LAmin (n, m) forming the minimum distance data group is selected as the A-side maximum distance data LAmax (n, m). , The largest of some or all of the minimum distance data LBmin (n, m) forming the minimum distance data group is selected as the B side maximum distance data LBmax (n, m), and the A side maximum distance data LAmax (n, m) is selected. It is desirable that the larger one of m) and B-side maximum distance data LBmax (n, m) is selected as the maximum distance data Lmax (n, m). Furthermore, it is desirable that the start point selection step described above selects the vertices A (n) and B (m) forming the maximum distance data Lmax (n, m) as start points.

In the pre-correction bone model acquisition step, the pre-correction bone model is acquired by constructing STL data representing the outer surface of the bone to be corrected by a plurality of triangle groups in the pre-correction bone model acquisition step of the present invention. In the vertex setting step, the intersections of the sides constituting the triangle group constituting the STL data related to the pre-correction bone model and the cut planes a and b are set at the vertices A (n) and B (m), respectively. It is desirable that Further, the method for forming the artificial bone model for compensation according to the present invention acquires a bone model of a healthy bone that is in a plane-symmetrical positional relationship with a bone to be corrected and a bone model that is plane-symmetrical as a reference bone model. It is preferable that the cutting planes a and b are determined based on the reference bone model in the cutting plane derivation step.

The method for forming the artificial bone model for compensation of the present invention is characterized in that the artificial bone for replacement is formed by using the STL data obtained by the method for forming the artificial bone model for compensation of the present invention described above.

The medical simulation system of the present invention is characterized in that the three-dimensional image of the artificial bone for compensation is formed using the method for forming the artificial bone model for supplement of the present invention described above.

The medical three-dimensional image acquisition method of the present invention is characterized by having a binarization step, a region setting step, a region resetting step, and a three-dimensional step. In the present invention, the binarization step is a step of converting a plurality of medical tomographic images into two-color tomographic images that are two-color images with a threshold set based on the CT value as a boundary. In the present invention, in the region setting step, a region corresponding to a selection region set in one of the two-color tomographic images obtained in the binarization step is selected as a selection region in another two-color tomographic image. This is a step of setting an area. Further, the region resetting step is performed from a previously set region set as a selection region in the region setting step in one two-color tomographic image selected from each two-color tomographic image set in the region setting step. This is a step of resetting a region excluding a part as a selection region and resetting a region corresponding to the reset selection region as a selection region in another two-color tomographic image. The three-dimensionalization step is a step of forming a three-dimensional image by combining two-color tomographic images obtained through the region setting step and the region resetting step.

The method for acquiring a medical three-dimensional image according to the present invention can use a medical tomographic image composed of tomographic images in three directions of X, Y, and Z that intersect each other. The present invention provides an X-directional tomographic image group consisting of tomographic images in the X direction, a Y-directional tomographic image group consisting of tomographic images in the Y direction, and a Z-directional tomographic image group consisting of tomographic images in the Z direction. The tomographic image is converted into a two-color tomographic image in the binarization step to form an X-direction two-color tomographic image group, a Y-direction two-color tomographic image group, and a Z-direction two-color tomographic image group. Is possible. The medical three-dimensional image acquisition method of the present invention is the region setting step in which one of the X direction two-color tomographic image group, the Y direction two-color tomographic image group, and the Z direction two-color tomographic image group is selected. An area corresponding to a selected area set in one two-color tomographic image included in the two-color tomographic image group is another two-color tomographic image included in the selected one-color tomographic image group, and is not selected. It is desirable to set a region as a selection region in a two-color tomographic image included in another two-color tomographic image group. The medical three-dimensional image acquisition method of the present invention is a region selected from the X direction two-color tomographic image group, the Y direction two-color tomographic image group, and the Z direction two-color tomographic image group in the region resetting step. An area excluding a part of the preset area set as the selection area in one two-color tomographic image included in the two-color tomographic image group is reset as the selection area, and the reset selection area is set as the selection area. It is desirable that the corresponding area is reset as a selection area in another two-color tomographic image.

The medical three-dimensional image acquisition method of the present invention preferably includes a surface forming step of forming a three-dimensional image by combining the two-color tomographic images of the regions set in the region setting step.

If the above-described method for acquiring a medical three-dimensional image of the present invention is used, a medical simulation system capable of forming a three-dimensional image of a predetermined part included in a plurality of medical tomographic images can be provided.

According to the method for forming an artificial bone model for compensation of the present invention, cutting of bone fragments A and B formed by cutting and separating the pre-correction bone model acquired in the pre-correction bone model acquisition step in the cutting plane derivation step It becomes possible to easily and accurately acquire STL data in which the outer surface of the artificial bone to be compensated between the surfaces a and b is expressed by a plurality of triangle groups. Specifically, the STL data acquired by the present invention crosses between the cut surfaces a and b between the vertices A (n) and B (m) set on the outer circumference of the cut surfaces a and b in the vertex setting step. In this way, it is formed so as to surround the entire circumference by sequentially connecting the line segments, but an appropriate apex A (n), B (m) must be selected as the starting point when forming the line segments. In this case, an error may occur in the finally formed STL data. Further, unless an appropriate starting point is selected, it becomes necessary to reconstruct the STL data many times in order to prevent the above-described error, and it takes a considerable amount of time to construct the STL data.

Based on this knowledge, in the method for forming an artificial bone model for compensation according to the present invention, the length of a candidate for a segment for constructing STL data (hereinafter also referred to as “STL construction line”) is scrutinized, and an STL construction line is obtained. By using the vertices A (n) and B (m) that are long in the possible line segments as starting points, the accuracy of the STL data is improved, and the construction of the STL data is facilitated. Specifically, the shortest line segment connecting between A (n) and B (m) is the STL construction line. Further, when the STL construction line is sequentially constructed, the STL construction line is constructed with the vertices A (n) and B (m) that are the largest among the candidates of the STL construction line as starting points. Therefore, it is considered that the error can be minimized. Therefore, in the present invention, the length of the STL construction line starting from each vertex A (n) is confirmed by performing the minimum distance derivation operation A for some or all of the p vertices A (n), The vertexes A (n) and B (m) that make the maximum in a part or all of the data constituting the minimum distance data group constructed by the minimum distance deriving operation A are selected as starting points. Therefore, according to the present invention, it is possible to improve the accuracy of STL data and to easily construct STL data.

According to the present invention, it is possible to optimally design a replacement artificial bone without depending on a doctor's rule of thumb in the planning stage before surgery. In addition, if an artificial bone model for compensation is constructed according to the present invention, an artificial bone shaped into an ideal shape and size before surgery can be provided, so that the time required for surgery is reduced and the burden on the patient is reduced. It becomes possible to contribute to.

In the method for forming the artificial bone model for compensation of the present invention, the distance between the line segment connecting the vertices A (n) and B (m + 1) and the line segment connecting the vertices A (n + 1) and B (m) is calculated. Since the short line segment is selected as the line segment constituting the STL data, it is possible to accurately represent the triangle group composed of the STL construction line that forms the outer surface of the artificial bone for replacement.

As described above, when the minimum distance data group construction step is to perform the minimum distance derivation operation B in addition to the minimum distance derivation operation A, in the maximum distance selection step, the A side maximum distance data LAmax (n, m) and If the B-side maximum distance data LBmax (n, m) is selected, and the larger one of these is selected as the maximum distance data Lmax (n, m), it is even more reliable between the cut surfaces a and b. It becomes possible to select vertices A (n) and B (m) having a positional relationship with an interval as a starting point. Therefore, according to the present invention, it is possible to construct the STL data that constitutes the artificial bone model for compensation more accurately.

As described above, the method for forming the artificial bone model for compensation according to the present invention includes each side constituting the triangle group forming the STL data acquired when the pre-correction bone model is constructed in the pre-correction bone model acquisition step. Intersections with the cutting planes a and b are set at vertices A (n) and B (m), respectively. Therefore, when the artificial bone model for compensation is formed according to the present invention, the STL construction lines forming the bone fragments A and B and the STL construction lines constituting the artificial bone model for compensation are the vertices A (n) and B (m). Will be shared. Therefore, according to the present invention, it is possible to easily obtain a three-dimensional image showing a state in which the artificial bone for replacement is embedded between the bone fragments A and B.

Here, for example, many of the bones that make up the human body have a plane-symmetric shape on the left and right, so when bone correction is performed by osteotomy, normal bones that are in a plane-symmetric positional relationship with the deformed bone If the position and shape of a simple bone are used as an index, the position to be cut can be set easily and appropriately, and the cut surfaces a and b can be formed. In the method for forming an artificial bone model for supplementation according to the present invention, a reference bone model acquisition step is provided, and a healthy bone that is in a plane-symmetrical positional relationship with the bone to be corrected is acquired as a reference bone model. Therefore, it is possible to easily and appropriately determine the bone cutting position with reference to the reference bone model in the cutting plane derivation step.

In the osteotomy, if the artificial bone for compensation is formed by using the STL data obtained by the method for forming the artificial bone model for compensation as described above, like the method for forming the artificial bone model for supplement of the present invention, It is possible to easily and highly accurately form a supplemental artificial bone that is optimal for use.

As in the medical simulation system of the present invention, if a three-dimensional image of a replacement artificial bone model is formed using the above-described method for forming a replacement artificial bone model of the present invention, an operation by osteotomy is performed. It is possible to plan surgery and the like using a three-dimensional image of the artificial bone for replacement.

In the medical three-dimensional image acquisition method of the present invention, the medical tomographic image is converted into a two-color image in the binarization step. In the present invention, since the two-color imaging of the medical tomographic image in the binarization step is performed based on a threshold value set with reference to the CT value, the two-color tomographic image obtained in the binarization step is It becomes possible to easily separate into a region including a desired portion and a region including other portions.

Further, in the medical three-dimensional image acquisition method of the present invention, since the medical tomographic image is converted into a two-color image using the CT value which is a dimensionless number as an index, the density and color tone of the provided medical tomographic image, etc. Without being influenced by the above, it is possible to easily and accurately separate the region including the desired region from the other region. Therefore, according to the method for acquiring a medical three-dimensional image of the present invention, it is possible to accurately acquire a three-dimensional image of a desired part using a medical tomographic image captured by any X-ray CT apparatus. It becomes.

As described above, by forming a two-color image, it is possible to minimize the data capacity of the image used in the process until the three-dimensional image is formed. Therefore, in the medical three-dimensional image acquisition method of the present invention, the information processing capability required for the computer for image processing is minimized, and it is possible to perform image processing quickly and smoothly.

In the medical three-dimensional image acquisition method of the present invention, in the region setting step, the region corresponding to the selected region set in one of the plurality of two-color tomographic images obtained by the binarization step By setting a region as a selection region in another two-color tomographic image, a portion corresponding to the selection region is also set as a selection region in another two-color tomographic image. Therefore, in the medical three-dimensional image acquisition method of the present invention, if a region including a portion to be converted into a three-dimensional image in any of a plurality of two-color tomographic images is set as a selection region, another two-color tomographic image is obtained. In this case, an area including a portion to be converted into a three-dimensional image is selected as a selection area, and setting of the selection area is extremely easy.

Here, in one of a plurality of two-color tomographic images existing in the region setting step described above, a region is set as a selection region, and a region corresponding thereto is set as a selection region in another two-color tomographic image; In this case, when the other two-color tomographic image is referred to, there is a possibility that a portion that does not desire three-dimensional imaging is included in the selected region. Therefore, in order to eliminate such inconvenience, in the medical three-dimensional image acquisition method of the present invention, an area resetting step is provided, and selection is performed by excluding a part from the already set areas set as the selection areas. The area is reset, and the area corresponding to the reset selection area can be reset as a selection area in another two-color tomographic image. Therefore, according to the method for acquiring a medical three-dimensional image of the present invention, by combining the two-color tomographic images obtained through the region setting process and the region resetting process in the three-dimensionalization process, An original image can be reliably formed.

As described above, since the medical three-dimensional image acquisition method of the present invention performs subsequent processing using the two-colored tomographic image after the binarization step, X crossing each other as a medical tomographic image. Even if an image composed of tomographic images in the three directions Y, Y, and Z is used, an excessive load is not applied to the computer for image processing, and image processing can be performed smoothly. In addition, by using a two-color tomographic image obtained by dichroizing a medical tomographic image, a medical tomographic image composed of tomographic images in three directions X, Y, and Z intersecting each other is converted into a medical three-dimensional image. It can be used for acquisition, and a more accurate three-dimensional image can be formed for a desired site.

In the medical three-dimensional image acquisition method of the present invention, in the region setting step, one two-color tomographic image group selected from the two-color tomographic image group for each of the X, Y, and Z directions is included. A region corresponding to the selected region set in the color tomographic image is included in another two-color tomographic image included in the selected two-color tomographic image group or another two-color tomographic image group that is not selected. A region is set as a selection region in the color tomographic image. In the medical three-dimensional image acquisition method of the present invention, in the region resetting step, the two-color tomographic image group selected from the two-color tomographic image group in each of the X, Y, and Z directions is included. In one two-color tomographic image, an area excluding a part from the already set area as the selection area is reset as the selection area, and the area corresponding to the reset selection area is the other two areas. The color tomographic image is reset as the selected region.

That is, when the selection region is set or reset in one two-color tomographic image selected from a large number of two-color tomographic images forming an X, Y, Z two-color tomographic image group, other two colors existing in large numbers. Also in the tomographic image, an area corresponding to the selection area described above is set as the selection area in conjunction with this, and there is no need to perform area setting or resetting for each two-color tomographic image. Therefore, in the method for acquiring a medical three-dimensional image according to the present invention, a region including a part where a three-dimensional image is to be acquired is confirmed from three directions of X, Y, and Z directions, and is designated as a selection region or already designated. By re-setting the selected area as an area that is partly excluded from the already set area, it is possible to reliably set the area that is difficult to confirm in other two-color tomographic images as the selected area. Is possible. Therefore, according to the medical three-dimensional image acquisition method of the present invention, it is possible to set the selected region more easily and accurately.

In addition, the medical three-dimensional image acquisition method of the present invention provides a surface forming step of forming a three-dimensional image by combining two-color tomographic images of the region set in the region setting step. It is easy to determine whether the area specified as the selection area in Fig. 2 includes an area that is not necessary for creating a 3D image, and where the unnecessary area is included in the two-color tomographic image. It becomes possible to judge and specify. Therefore, by providing the surface forming step, it is possible to improve the work efficiency of the region resetting step and obtain a medical three-dimensional image more easily and accurately.

By using the above-described method for acquiring a medical three-dimensional image according to the present invention, it is possible to form a three-dimensional image of a predetermined part included in a plurality of medical tomographic images, and to a computer having an extremely high information processing capability. It is possible to provide a medical simulation system capable of acquiring a three-dimensional image smoothly without depending on it. In addition, since this medical simulation system uses the above-described method for acquiring a medical three-dimensional image, an accurate three-dimensional image can be easily obtained without relying on a doctor or a specialized operator who has experienced operation. It can be acquired.

It is a block diagram which shows the structure of the simulation system which concerns on one Embodiment of this invention. It is a figure which shows an example of the display state of the bone model before correction | amendment, and a reference | standard bone model. It is a figure which shows an example of the display screen displayed on an output screen when determining the osteotomy position of the bone model before correction. It is the perspective view which showed typically the relationship between the cut surfaces a and b of bone fragments A and B, and the STL construction line of bone fragments. It is the perspective view which showed typically the state after adjusting the position and angle of each bone piece A and B in a bone piece position correction process. (A) is explanatory drawing explaining the relationship of vertex A (n) and B (m) at the time of deriving distance LA (n, m), (b) derives distance LB (n, m). It is explanatory drawing explaining the relationship of the vertex A (n) and B (m) at the time. It is a perspective view which shows the artificial bone model Z for compensation. It is a perspective view which shows the state which fitted the artificial bone model Z for a compensation between the bone fragments A and B. FIG. It is a flowchart of the formation method of the artificial bone model for the compensation which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the medical simulation system which concerns on one Embodiment of this invention. It is a flowchart which concerns on the acquisition method of the medical three-dimensional image of this invention. It is a figure which shows the state which output the two-color tomographic image acquired in the binarization process on the output screen. It is a figure which shows the state by which the selection area | region was set in the area | region setting process. It is a figure which shows a surface image. (A) is a figure which shows an example of the two-color tomographic image acquired in a binarization process, (b) is a figure which shows the state by which the selection area | region was set in the two-color tomographic image shown to (a). . FIG. 16 is a diagram illustrating a state in which a part of a region is excluded from a selection region in the two-color tomographic image illustrated in FIG. It is a figure which shows an example of the three-dimensional image acquired in a three-dimensionalization process. It is a perspective view which shows an expansion | swelling model and a cut surface. (A) is the perspective view which demonstrated the formation method of the cutting plate typically, (b) is the perspective view which showed an example of the cutting plate.

≪Method of forming artificial bone model for supplement, artificial bone for supplement, and medical simulation system≫
Next, a method for forming a replacement artificial bone model according to an embodiment of the present invention and a replacement artificial bone 10 formed by this method will be described in detail with reference to the drawings. The method for forming the artificial bone model for compensation of the present embodiment is performed using the simulation system 20. The simulation system 20 is constructed by installing software including an execution program for executing the method for forming the artificial bone model for compensation according to the present embodiment on a conventionally known computer. As shown in FIG. 1, the simulation system 20 includes a pre-correction bone model acquisition unit 22, a reference bone model acquisition unit 24, a cutting plane deriving unit 26, a vertex setting unit 28, a distance deriving unit 30, and a minimum distance. Data construction means 32, maximum distance selection means 34, start point selection means 36, and STL data construction means 38 are provided.

The pre-correction bone model acquisition means 22 acquires a three-dimensional model (hereinafter also referred to as “pre-correction bone model” X) of a bone to be corrected (hereinafter also referred to as “correction target bone”) that has been deformed into an abnormal state. Means. The pre-correction bone model acquisition means 22 can extract an image relating to the bone to be corrected from DICOM (Digital Imaging and Communication in Medicine) data relating to a CT image obtained by, for example, so-called X-ray CT (Computed Tomography). It is. Further, the pre-correction bone model acquisition means 22 can acquire STL data in which the outer surface of the correction target bone is expressed by a group of triangles formed using a plurality of line segments (STL construction lines). As shown in FIG. 2, the simulation system 20 can display the pre-correction bone model X on the output screen based on the STL data acquired by the pre-correction bone model acquisition means 22.

The reference bone model acquisition means 24 is a three-dimensional model (hereinafter referred to as “reference bone model”) of a mirror image of a normal bone (hereinafter also referred to as “normal bone”) of the same patient having a plane symmetry relationship with the bone to be corrected. "Also called" Y "). The reference bone model acquisition means 24 extracts an image related to normal bone obtained by extracting from DICOM data related to a CT image obtained by X-ray CT or the like, similar to the above-mentioned pre-correction bone model acquisition means 22. A mirror image of the three-dimensional model of normal bone can be acquired as the reference bone model Y. The reference bone model acquisition means 24 can acquire STL data in which the outer surface of the reference bone is expressed by a plurality of triangle groups. As shown in FIG. 2, the simulation system 20 can display the reference bone model Y on the output screen based on the STL data acquired by the reference bone model 24. The reference bone model Y is used for adjusting the position of the bone to be corrected (hereinafter also referred to as “bone cutting position”), and the interval and angle adjustment of the bone fragments A and B obtained by cutting the bone. Can be used as an indicator.

The cut surface deriving means 26 is a means for deriving the cut surfaces a and b of the bone fragments A and B formed when the pre-correction bone model X is cut at the above-described osteotomy position. In the simulation system 20 of the present embodiment, as shown in FIG. 3, a virtual plane V can be displayed on the display screen, and the virtual plane V is arranged at an arbitrary osteotomy position on the pre-correction bone model X. At the same time, by adjusting the inclination of the virtual plane V, the cut planes a and b when the pre-correction bone model X is cut at this osteotomy position and angle can be derived.

The vertex setting means 28 sets a plurality (p) of vertices A (n) (n is a natural number from 1 to p) on the outer periphery of the cutting surface a derived by the cutting surface deriving means 26 described above, and cutting This is means for setting a plurality (q) of apexes B (m) (m is a natural number from 1 to q) on the outer periphery of the surface b. The vertices A (n) and B (m) set by the vertex setting means 28 are respectively represented when the supplementary artificial bone model Z is expressed in the STL format that expresses the surface shape by a plurality of triangle groups. It is a vertex. In the present embodiment, as shown in FIG. 4, the vertex setting unit 28 includes the cutting planes a and b derived by the cutting plane deriving unit 26 and the pre-correction bone model X acquired by the pre-correction bone model acquisition unit 28. Intersections with the line segments constituting the STL data are vertices A (n) and B (m). Therefore, in this embodiment, the numbers p and q of the vertices A (n) and B (m) are the same.

By cutting (dividing) the pre-correction bone model X at the position and angle of the virtual plane V as described above, the positions of the bone fragments A and B are adjusted along the reference bone model Y, respectively. As a result, the bone model representing the bone fragments A and B has a positional relationship after correction by osteotomy, and a defect portion L to be compensated by the artificial bone for compensation occurs between the bone fragments A and B ( (See FIG. 5).

The distance deriving means 30 is for deriving the distance of the defect portion L, and by performing the minimum distance deriving operation A and the minimum distance deriving operation B, the line segment constituting the STL data of the artificial bone model Z for compensation It is possible to derive the distance of (STL construction line). Specifically, the minimum distance deriving operation A is performed between one point constituting p vertices A (n) provided on the outer periphery of the cutting surface a on the bone fragment A side and the cutting surface b on the bone fragment B side. A distance LA (n, m) to a part or all of each vertex B (m) provided on the outer periphery is derived for each vertex B (m) (see FIG. 6A), and the derived distance LA is derived. This is an operation of selecting the smallest one from (n, m) as the minimum distance data LAmin (n, m). The minimum distance data LAmin (n, m) derived by the minimum distance deriving operation A corresponds to the length when the STL construction line is formed starting from each vertex A (n). A line segment connecting the vertices A (n) and B (m) forming the minimum distance data LAmin (n, m) is a candidate for a line segment (STL construction line) constituting the STL data of the artificial bone model Z for compensation. It will be.

Similarly, in the minimum distance deriving operation B, the distance LB (n, m) between one point constituting q vertices B (m) and a part or all of each vertex A (n) is set to each vertex B ( This operation is derived every m) (see FIG. 6B), and the smallest one is selected as the minimum distance LBmin (n, m) from the derived distance LB (n, m). The minimum distance data LBmin (n, m) derived by the minimum distance deriving operation B corresponds to the length when the STL construction line is formed starting from each vertex B (m). The line segment connecting the vertices A (n) and B (m) forming the minimum distance data LBmin (n, m) is a line segment that is a candidate for the STL construction line of the artificial bone model Z for compensation.

The minimum distance data constructing means 32 is a means for constructing a minimum distance database LminDB in which the minimum distance data LAmin (n, m) and LBmin (n, m) derived by the distance deriving means 30 are databased. The minimum distance database LminDB includes an A side minimum distance database LAminDB composed of minimum distance data LAmin (n, m) starting from the vertex A (n), and minimum distance data LBmin (starting from the vertex B (m). n, m) and the B-side minimum distance database LBminDB.

The maximum distance selection means 34 refers to the minimum distance database LminDB constructed by the minimum distance data construction means 32 and selects the one with the maximum distance. In the present embodiment, the maximum distance selection means 34 first selects the largest of the minimum distance data LAmin (n, m) included in the A side minimum distance database LAminDB as the A side maximum distance data LAmax (n, m). Select as. Similarly, the maximum distance selection means 34 selects the largest one from the minimum distance data LBmin (n, m) included in the B side minimum distance database LBminDB as B side maximum distance data LBmax (n, m). . The maximum distance selection means 34 selects the larger one of the A side maximum distance data LAmax (n, m) and the B side maximum distance data LBmax (n, m) selected in this way as the maximum distance data Lmax (n, m). ) To select.

The start point selection means 36 is a means for selecting the vertices A (n) and B (m) that are the start points when constructing the STL data of the artificial bone model Z for compensation. The start point selection means 36 uses the vertices A (n) and B (m) forming the maximum distance data Lmax (n, m) selected by the maximum distance selection means 34 as the start points A (1) and B (1 ) (N = 1, m = 1).

The STL data construction means 38 constructs STL data that forms the outer surface of the artificial bone for supplementation. The STL data construction unit 38 uses the vertices A (1) and B (1) selected by the above-described start point selection unit 36 as a start point, and a section between the vertices A (n) and B (m) a, STL data representing the outer surface of the artificial bone for compensation is constructed by a plurality of triangle groups by connecting line segments sequentially across the region between b.

More specifically, the STL data constructing means 38 first constructs a line segment for constructing the STL data of the artificial bone model Z for compensation (the line segment connecting the vertices A (1) and B (1) serving as the start points described above ( STL data construction line). Thereafter, the length L (1,2) of the line segment connecting the vertex B (2) and the vertex A (1) adjacent to the vertex B (1) in the circumferential direction of the cut surface b, and the vertex A (1 ) Is compared with the length L (2, 1) of the line segment connecting the vertex A (2) and the vertex B (1) adjacent to each other in the circumferential direction of the cut surface a, and the shorter line is compared. Minute is selected as the STL construction line. Here, when L (1,2) is shorter, it is compensated by a triangular area formed by connecting A (1), B (1), and B (2) with a line segment (STL construction line). A part of the outer surface of the artificial bone model Z is configured. If L (2,1) is shorter, it is compensated by a triangular area formed by connecting A (1), B (1), and A (2) with line segments (STL construction lines). A part of the outer surface of the artificial bone model Z is configured. Thereafter, similarly to this, among the line segment connecting the vertices A (n) and B (m + 1) and the line segment connecting the vertices A (n + 1) and B (m), the line segment having the short distance is sequentially STL. By selecting as construction lines, the vertices A (n) and B (m) are connected by STL construction lines as shown in FIG. 7, and A (n), B (m), A (n + 1) are connected. A part of the outer surface of the artificial bone model Z for replacement is sequentially formed by a triangular region formed by connecting the STL construction lines to each other or between A (n), B (m), and B (m + 1). Go. As a result, the artificial bone model Z for compensation is formed in which the space formed between the cutting planes a and b is surrounded by the triangle group formed by the STL construction line over the entire circumference.

The STL data of the artificial bone model Z for supplement constructed by the STL data construction means 38 forms the artificial bone model Z for supplement in the simulation system 20, and the output screen of the artificial bone model Z alone for supplement as shown in FIG. It is possible to display in a state where it is displayed above or in a state where it is fitted in a defect portion L formed between the bone fragments A and B as shown in FIG. Further, if the STL data of the artificial bone model Z for compensation constructed by the STL data construction means 38 is used, it is possible to form the artificial bone 10 for compensation by a modeling method such as an optical modeling method.

Subsequently, a method for forming the artificial bone model Z for compensation using the simulation system 20 and a method for forming the artificial bone 10 for compensation will be described. In the simulation system 20, the artificial bone model Z for compensation is constructed through the steps shown in Step 1-1 to Step 1-9 shown in FIG. Specifically, the pre-correction bone model acquisition step according to step 1-1 is a step of acquiring a three-dimensional model (pre-correction bone model X) of the bone to be corrected by the pre-correction bone model acquisition means 22 described above. In step 1-1, STL data related to the pre-correction bone model X is acquired, and the pre-correction bone model X is constructed based on the STL data. The pre-correction bone model X acquired in step 1-1 is displayed on the output screen of the computer as shown in FIG.

When step 1-1 described above is completed, the process proceeds to a reference bone model acquisition process according to step 1-2. The reference bone model acquisition step is a step of acquiring the reference bone model Y by the reference bone model acquisition means 24. In step 1-2, a reference bone model Y is obtained by creating a mirror image of a normal bone of the same patient having a plane symmetry relationship with the bone to be corrected and modeling it into a three-dimensional model. The reference bone model Y acquired in step 1-2 is displayed side by side with the pre-correction bone model X on the output screen of the computer as shown in FIG.

When the reference bone model Y is acquired in step 1-2 described above, the process proceeds to step 1-3. The cutting plane deriving process according to step 1-3 is a process performed by the cutting plane deriving means 26 described above, and a cutting plane a formed when the pre-correction bone model X is cut at a specified osteotomy position. , B are derived. Specifically, when the process proceeds to step 1-3, the position and angle of the virtual plane V for derivation of the cutting plane displayed on the display screen using an input device such as a mouse or a keyboard are set as the reference bone model Y. It becomes possible to adjust suitably while comparing. By setting the position and angle of the virtual plane V, when the osteotomy position and the angle for performing osteotomy are specified in the pre-correction bone model X displayed on the output screen, the pre-correction is performed at this position and angle. The cut surfaces a and b formed when the bone model X is cut are derived.

When the cut surfaces a and b are derived in step 1-3, the process proceeds to the vertex setting process in step 1-4. In the vertex setting step, a plurality (p, q) of vertices A (n) and B (m) are set on the outer peripheries of the cut surfaces a and b by the vertex setting means 28. In the present embodiment, as shown in FIG. 4, the intersection points of the cut planes a and b and the STL construction line constituting the pre-correction bone model X constructed in Step 1-1 are the vertices A (n) and B (m). Set as

When the derivation of the cutting planes a and b and the setting of the vertices A (n) and B (m) are completed in steps 1-3 and 1-4, the process proceeds to the bone fragment position correcting process in step 1-5. . In the bone fragment position correcting step, the positions and angles of the bone fragments A and B are adjusted along the reference bone model Y described above. Thereby, a defect portion L as shown in FIG. 5 is formed between the cut surfaces a and b formed in the bone fragments A and B.

When the bone fragment position correcting process according to step 1-5 is completed, the process proceeds to the distance deriving process according to step 1-6. The distance deriving step is performed by the distance deriving means 30. In the distance deriving step, the distance LA (n, m) from each vertex B (m) is derived for each of the p vertices A (n) by the minimum distance deriving operation A (see FIG. 6A). The smallest one is selected as the minimum distance data LAmin (n, m) from the obtained distance LA (n, m). Further, for each of the q vertices B (m) by the minimum distance derivation operation B, the distance LB (n, m) from each vertex A (n) is derived (see FIG. 6B), and the derived distance The smallest one of LB (n, m) is selected as the minimum distance data LBmin (n, m). The selected minimum distance data LAmin (n, m) and minimum distance data LBmin (n, m) are databased by the minimum distance data construction means 32, respectively, and the A side minimum distance database LAminDB and the minimum distance are selected. A minimum distance database LminDB configured by the data LBmin (n, m) is constructed.

As described above, when the minimum distance database LminDB is constructed in step 1-6, the control flow proceeds to the maximum distance selection step in step 1-7. In step 1-7, the minimum distance database LminDB is referred to by the maximum distance selection means 34, and the minimum distance data LAmin (n, m), LBmin (n, m) included in the A and B side minimum distance databases LAminDB and LBminDB. ) Is selected as A side maximum distance data LAmax (n, m) and B side maximum distance data LBmax (n, m). Thereafter, the maximum distance selection means 34 compares the A and B side maximum distance data LAmax (n, m) and LBmax (n, m), and selects the larger one as the maximum distance data Lmax (n, m). Is done. When the maximum distance data Lmax (n, m) is selected, the process proceeds to the start point selection process according to step 1-8.

In step 1-8, the starting point selection means 36 selects a starting point for constructing STL data of the artificial bone model Z for compensation from a plurality of set vertices A (n) and B (m). The Specifically, in step 1-8, the vertices A (n) and B (m) forming the maximum distance data Lmax (n, m) selected in step 1-7 are used as start points A (1), B Selected as (1).

When the starting points A (1) and B (1) are selected, the process proceeds to the STL data construction process according to step 1-9, and the STL construction line representing the outer surface of the artificial bone for replacement is sequentially determined. STL data is constructed. Specifically, in step 1-9, the STL data construction means 38 connects the vertices A (n) and B (m) with the STL construction line starting from the start points A (1) and B (1). Thus, STL data representing the outer surface of the artificial bone for compensation expressed by a plurality of triangle groups is constructed.

When the STL data related to the artificial bone for compensation is constructed in step 1-9, as shown in FIGS. 7 and 8, the artificial bone model Z for supplementation is displayed by the simulation system 20 alone, It becomes a state which can be displayed in the state fitted in the missing part L between B. In addition, by inserting the artificial bone model Z for compensation between the three-dimensional models representing the bone fragments A and B formed by cutting the pre-correction bone model X related to the correction target bone, a corrected bone model ( Hereinafter, the post-correction bone model) can be displayed. Furthermore, by using the STL data constructed by the STL data construction means 38, it becomes possible to prepare the artificial bone 10 for supplementation used for surgery using a modeling method such as an optical modeling method before the operation.

As described above, in the method for forming the artificial bone model Z for compensation of the present embodiment, the length of what can be a candidate for the STL construction line forming the artificial bone model Z for compensation in the distance deriving step (step 1-6) is set. The longest one is selected in the maximum distance selection step (step 1-7), and the vertices A (n) and B (m) that make the longest are selected as the starting points A (1) and B Selected as (1) (step 1-8). Therefore, according to the above-described method for forming the artificial bone model Z for compensation, errors in the STL construction line forming the artificial bone model Z for compensation are unlikely to occur, and the artificial bone model Z for compensation can be constructed easily and with high accuracy. Is possible.

In the above embodiment, in the distance deriving step, the distance LA (n, m) to each vertex B (m) is derived for each of the p vertices A (n), and each of the q vertices A (n) is derived. In this example, the minimum distance data LAmin (n, m) and the minimum distance data LBmin (n, m) are derived by deriving the distance LB (n, m) from each vertex A (n). The invention is not limited to this. Specifically, a distance LA (n, m) between a part of p vertices A (n) and a part or all of each vertex B (m) is derived, and the derived distance LA ( The smallest one of n, m) may be selected as the minimum distance data LAmin (n, m). Similarly, a distance LB (n, m) between some of the q vertices B (m) and a part or all of each vertex A (n) is derived, and the derived distance LB (n, m The smallest of m) may be selected as the minimum distance data LBmin (n, m). That is, vertices A (n) and B in deriving the distances LA (n, m) and LB (n, m) from either the p vertices A (n) or q vertices B (m). It is good also as excluding from the candidate of (m).

In the above embodiment, in the maximum distance derivation step, the maximum one is selected from the minimum distance data LAmin (n, m) constituting the A side minimum distance database LAminDB, and the minimum constituting the B side minimum distance database LBminDB is selected. Although the example which selects the largest thing from distance data LBmin (n, m) was illustrated, this invention is not limited to this. Specifically, a part of the minimum distance data LAmin (n, m) and LBmin (n, m) constituting the A side minimum distance database LAminDB and the B side minimum distance database LBminDB is selected from the selection targets in the maximum distance derivation step. It is also possible to exclude.

If the artificial bone model Z for supplementation is constructed by the above-described method for forming the artificial bone model Z for compensation and the simulation system 20, the artificial bone for supplementation is designed so as to have an optimum size and shape without depending on the doctor's rule of thumb. can do. Moreover, if the artificial bone model Z for supplementation is constructed by the above-described forming method and the simulation system 20, it becomes possible to prepare and prepare an artificial bone molded into an ideal shape and size before the operation. Therefore, the time required for the operation can be shortened and the burden on the patient can be reduced.

As described above, in the method for forming the artificial bone model for compensation according to the present embodiment, the intersections between the STL construction line and the cut planes a and b related to the pre-correction bone model are the vertices A (n) and B (m), respectively. Set to Therefore, if the artificial bone model Z for supplementation is formed according to the present embodiment, the vertices A (n), B are composed of the STL construction line forming the bone fragments A and B and the STL construction line constituting the artificial bone model Z for supplementation. (M) is shared, and it is possible to easily acquire a three-dimensional image showing a state in which the artificial bone for replacement is embedded between the bone fragments A and B. In the above-described embodiment, an example in which the intersections of the STL construction line and the cut planes a and b related to the pre-correction bone model are set as vertices A (n) and B (m) is exemplified. The vertexes A (n) and B (m) are not limited and can be appropriately set regardless of the STL construction line related to the pre-correction bone model.

In the above-described method for forming the artificial bone model for compensation, in the bone fragment position correcting step (step 1-5), a three-dimensional model of a mirror image of a normal bone having a plane-symmetric positional relationship with the bone to be corrected that has been deformed into an abnormal mode The positions and postures of the bone fragments A and B that have been cut and separated based on the reference bone model Y are adjusted, and the size and shape of the defect portion L formed between the cut surfaces a and b can be easily specified. . Therefore, according to the above-described method for forming the artificial bone model for replacement, a three-dimensional model of the artificial bone for replacement (artificial bone model Z for replacement) to be supplemented between the bone fragments A and B when performing osteotomy, The artificial bone for supplementation can be formed easily and accurately. In the above embodiment, the position of the bone fragments A and B, the interval between the cut surfaces a and b, the osteotomy position, the bone, based on the reference bone model Y acquired in the reference bone model acquisition step (step 1-2). Although the structure which can adjust a cutting angle etc. was illustrated, this invention is not limited to this. That is, without acquiring the reference bone model Y, the positions of the bone fragments A and B, the interval between the cut surfaces a and b, the osteotomy position, the osteotomy angle, and the like are appropriately set, so It is good also as constructing the STL data concerning the bone model Z of the artificial bone 10 for the replacement to determine the arrangement and thereby to fill the defect portion L formed between the bone fragments A and B by the method described above.

≪About medical 3D image acquisition method and medical simulation system≫
Next, a medical simulation system 110 and a medical three-dimensional image acquisition method according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 10, the medical simulation system 110 is constructed by installing software having an execution program for executing the method for acquiring a medical three-dimensional image according to the present embodiment on a conventionally known computer. Is done. The medical simulation system 110 includes an image acquisition unit 120, a binarization unit 122, a region setting unit 124, a surface forming unit 126, a region resetting unit 128, a three-dimensionalization unit 130, and three-dimensional image data. Output means 132.

The image acquisition means 120 can read image data such as DICOM (Digital Imaging and Communication in Medicine) data relating to a CT image obtained by X-ray CT (Computed Tomography). The image acquisition unit 120 is acquired as a tomographic image in three directions X, Y, and Z that intersect each other. A tomographic image group consisting of tomographic images in the X direction is classified as constituting an X direction tomographic image group. Similarly, a tomographic image group consisting of tomographic images in the Y direction is classified as constituting a Y direction tomographic image group, and a tomographic image group consisting of tomographic images in the Z direction constitutes a Z direction tomographic image group. being classified.

The binarizing means 122 is a threshold set with the medical tomographic images forming the X direction tomographic image group, Y direction tomographic image group, and Z direction tomographic image group acquired by the image acquiring means 120 as the CT value as a reference. Are classified into two gradations with a boundary as a two-color image. Specifically, the binarization unit 122 replaces the region having the gradation equal to or higher than the threshold value in each medical tomographic image with white, and replaces the region where the gradation is lower than the threshold value with black. Each medical tomographic image is converted into a two-color image. Thus, two X-direction two-color tomographic image groups obtained by dichroizing the tomographic image in the X direction, two Y-direction two-color tomographic image groups obtained by dichroizing the tomographic image in the Y direction, and two tomographic images in the Z direction. Colored Z-direction two-color tomographic image groups are respectively formed.

The region setting unit 124 is for selecting a region including a portion to be converted into a three-dimensional image from the two-color tomographic image obtained by binarization by the binarization unit 122 described above. The region setting unit 124 corresponds to a selection region when the region is set as a selection region in one of a plurality of two-color tomographic images obtained by binarization by the binarization unit 122. Has a function of designating a region as a selection region also in other two-color tomographic images. More specifically, in one of the two-color slice images forming the X-direction two-color tomographic image group, the Y-direction two-color tomographic image group, and the Z-direction two-color tomographic image group, a certain region is selected as the selection region. When the region is set, a portion corresponding to the selected region in the other two-color tomographic images included in the selected two-color tomographic image group is set as a selected region. Further, the two-color cross-sectional images included in the image group different from the image group to which the two-color cross-sectional images used for region setting belong among the two-color tomographic image groups in the X, Y, and Z directions are also described above. An area corresponding to the selected area is selected as a selected area and set.

In the medical simulation system 110 according to the present embodiment, it is possible to perform region setting by a segmentation method, and a portion such as a mouse is used to set a region to be set as a selection region in a two-color cross-sectional image displayed on the display screen. It can be specified using a device. Further, in the medical simulation system 110, it is possible to perform region setting by the region growing method. When a region in the region to be selected as a selection region is specified, it is assumed that the region belongs to the same region as the specified portion. The connected areas are expanded while being sequentially taken in and selected as the selection area.

The surface forming unit 126 has a function of forming a three-dimensional image by combining images related to the selected region set by the region setting unit 124. By forming the three-dimensional image by the surface forming unit 126, whether or not an unnecessary part is included in addition to the part where the three-dimensional image is to be acquired at the time when the region is set by the region setting unit 124. It becomes possible to confirm the position of the part.

The region resetting unit 128 excludes an unnecessary region (exclusion region) when acquiring a 3D image from the regions already set as the selection region by the region setting unit 124 and resets the selection region. Means. When the area resetting unit 128 resets the selected area in one two-color tomographic image selected from each of the two-color slice images set by the area setting unit 124, the area resetting unit 128 is already in the other two-color slice images. An area that is designated as an area to be selected is set as an area that is excluded from an area that corresponds to the exclusion area from an already set area that has been set. Therefore, the region resetting unit 128 resets a region obtained by removing the excluded region from the selected region in the two-color tomographic image included in any of the two-color tomographic image group in the X, Y, and Z directions. In each of the two-color sectional images forming the two-color tomographic image group in the X, Y, and Z directions, an area excluding the area corresponding to the excluded area can be reset as the selected area.

In the medical simulation system 110 of the present embodiment, it is possible to designate an unnecessary area (exclusion area) from the selected area by the segmentation method and reset the selected area. Specifically, in a two-color cross-sectional image that has already been set on the display area displayed on the display screen, by specifying a portion corresponding to the exclusion area using an input device such as a mouse, the exclusion area It is possible to reset the selection area by specifying.

The three-dimensionalization unit 130 forms a three-dimensional image by combining the two-color cross-sectional images of the selection region designated by the region designation unit 26 or the portion related to the selection region reset by the region resetting unit 128. It has the function to do. The three-dimensional image formed by the three-dimensionalization unit 130 can be output by the three-dimensional image data output unit 132 in a data format such as STL data.

Subsequently, the operation of the above-described medical simulation system 110 and the implementation method of the medical three-dimensional image acquisition method will be described with reference to the drawings. As shown in FIG. 11, the medical three-dimensional image acquisition method of the present embodiment is carried out through steps related to Step 2-1 to Step 2-9. The image acquisition step according to step 2-1 is a step of reading image data related to a CT image such as DICOM data by the image acquisition means 120 and acquiring it as a tomographic image in three directions of X, Y, and Z. The tomographic image data read in step 2-1 is an image having a large number of gradations such as a so-called gray scale image, and has a large data capacity for image processing as it is or three-dimensionalization.

Therefore, when the tomographic image data is read in the binarization process in step 2-1, each tomographic image is converted into a two-color image. Specifically, the tomographic images in the three directions X, Y, and Z acquired by the image acquisition unit 120 are all based on a region corresponding to a CT value equal to or greater than a threshold value set based on the CT value, and the threshold value. Are also classified as small areas. In each tomographic image, an area that is equal to or greater than the threshold is replaced with white, and an area that is below the threshold is replaced with black. In this way, each tomographic image is converted into a two-color tomographic image. More specifically, for example, when it is desired to obtain a three-dimensional image of a bone included in a tomographic image, by setting a threshold corresponding to a CT value of about 100, the region including the bone is replaced with white, Other areas are replaced with black.

The two-color tomographic images obtained by dichroizing the tomographic images in the X direction constitute an X-direction two-color tomographic image group. Similarly, each two-color tomographic image obtained by dichroizing the tomographic image in the Y direction constitutes a Y-direction two-color tomographic image group, and each two-color tomographic image obtained by dichroizing the tomographic image in the Z direction is A Z-direction two-color tomographic image group is configured. Each two-color tomographic image obtained in the dichroic process is displayed on an output screen of a computer in which the medical simulation system 110 is installed for each image group as shown in FIG. Also, the two-color tomographic image displayed on the output screen is changed from the displayed X, X, X by specifying or changing coordinates using an input device such as a mouse or keyboard connected to the computer. The position can be appropriately changed to a position moved in each of the Y and Z directions. Therefore, it is possible to display a two-color tomographic image at an arbitrary position (coordinates) on the output screen by specifying or changing the coordinates using the input device.

When each tomographic image is converted into a two-color image as described above, the process proceeds to each step related to Step 2-3 to Step 2-8, and is used when a three-dimensional image is constructed in each two-color tomographic image. The image area is set. Specifically, when the process shifts to the area setting process according to step 2-3, among the two-color tomographic images obtained in the above-described binarization process, as a selection area in the appropriately selected two-color tomographic image. An area corresponding to the set area is selected as a selection area in other two-color tomographic images.

More specifically, when the process proceeds to step 2-3, by operating an input device such as a mouse or a keyboard, an area to be selected in the two-color cross-sectional image displayed on the output screen, that is, It is possible to set a region that will correspond to the portion to be converted into a three-dimensional image. As described above, in this embodiment, the region can be set by both the segmentation method and the region growing method, and the three regions displayed on the output screen can be set by any method. An area to be a selection area can be selected by specifying an input device such as a mouse in one of the two-color tomographic images in the X, Y, and Z directions.

When a region to be selected is designated in one of the three X, Y, and Z-direction two-color tomographic images displayed on the output screen, the designated region is displayed as shown in FIG. A region colored with a color other than white and black is formed and distinguished from other regions. Specifically, when the selected region is designated by the region growing method, for example, when a part of the region indicated by the stitch-shaped hatching in FIG. 13 is selected, the entire hatched region is continuous. And the area is set as the selected area. On the other hand, when the region is set by the segmentation method, the region is set as a selection region by operating and selecting an input device such as a mouse or a keyboard so as to fill the entire region hatched in FIG. It becomes a state.

When the area to be the selection area is specified as described above, the area corresponding to the selection area is also colored in the other two-color tomographic images displayed on the output screen. Furthermore, as for the other two-color sectional images that are not displayed on the output screen when the selection area is designated, the area corresponding to the selection area is selected as the selection area as described above. Therefore, after setting the selection area, if another two-color image is displayed on the output screen by operating the input device, the area corresponding to the selection area described above is displayed in a colored state.

When the area is set in step 2-3 as described above, the process reaches step 2-4. In step 2-4, it is confirmed whether or not surface image formation is necessary, that is, whether or not it is necessary to form a three-dimensional image by combining images related to the selected region set by the region setting unit 124. If it is confirmed in step 2-4 that surface image formation is necessary, the process proceeds to step 2-5. If it is confirmed that surface image formation is not necessary, the process proceeds to step 2-7.

When the process has proceeded to step 2-5, the surface forming unit 126 combines the images related to the selected region set by the region setting unit 124 to form a three-dimensional image. As shown in FIG. 14, the three-dimensional image formed by the surface forming means 126 is displayed on the output screen of the computer as a surface image. As a result, whether or not the selected area set in the area setting process in Step 2-3 includes an unnecessary part in addition to the part to be acquired as a three-dimensional image, the position of the unnecessary part, etc. You can check if it does not exist.

When the formation of the surface image is completed in step 2-5, the process proceeds to step 2-6, and whether there is an area to be excluded from the already selected area set as the selection area in step 2-3 described above. Whether or not it is necessary to reset the selected area is confirmed. Similarly, when it is determined in step 2-4 that surface image formation is unnecessary, it is confirmed in step 2-8 whether or not there is an area to be excluded from the area set as the selection area. Is done. If it is determined in step 2-6 and step 2-8 that there is an area to be excluded from the area set as the selection area, and it is determined that the selection area needs to be reset, the process proceeds to step 2-7. If it is determined that there is no area to be excluded and that it is not necessary to reset the selected area, the process proceeds to step 2-9.

When the process proceeds to the area resetting process related to step 2-7, an area (exclusion area) that does not need to be acquired as a 3D image is selected from the area set as the selection area in step 2-3 by the area resetting unit 128. The excluded area is reset as the selected area. Specifically, for example, one of the two white areas depicted in the two-color cross-sectional image illustrated in FIG. 15A is an area indicating a portion to be converted into a three-dimensional image, and the other is the other area. In the case of a partial area, the area setting unit 124 may recognize it as a series of areas, for example, because both areas appear together in other two-color cross-sectional images. In such a case, when a selection region is specified using a two-color cross-sectional image other than that in FIG. 15A in the region setting process in step 2-3 described above, a mesh-like hatching in FIG. As indicated by, both of two white areas indicating different parts may be designated as selection areas.

Therefore, when there is an area to be excluded from the selected area, a position (coordinates) at which the excluded area can be determined is designated based on the above-described surface image or the like as shown in FIG. By specifying an exclusion area by operating an input device such as a mouse while the color slice image is displayed on the output screen, the area that is left excluded from the selection area (indicated by mesh hatching in FIG. 16) Can be reset as the selected area. When the selected area is reset, the other two-color tomographic images displayed on the output screen are reset to the area that excludes the area corresponding to the excluded area from the selected area. Become. In addition, when the selection area is reset, the area that excludes the area corresponding to the exclusion area from the selection area is reset as the selection area for the other two-color images that are not displayed on the output screen. become.

If the area resetting process according to step 2-7 is completed as described above, or if it is determined that the resetting of the selected area is unnecessary in step 2-6 or step 2-8, the process goes to step Proceed to the three-dimensional process according to 2-9. In step 2-9, the two-color cross-sectional images of the portion designated as the selection region are combined by the three-dimensionalizing means 130 and displayed on the output screen as a three-dimensional image as shown in FIG. Further, the three-dimensional image formed in step 2-9 can be output by the three-dimensional image data output means 132 in a data format such as STL data.

As described above, in the medical simulation system 110 and the medical three-dimensional image acquisition method shown in the present embodiment, the medical tomographic image is binarized through the steps related to Step 2-1 to Step 2-3. Into a two-color tomographic image. Therefore, the data capacity of the image (two-color tomographic image) handled in the process after step 2-3 is extremely small, and the information processing capability required for the computer for image processing in the process after step 2-3 is minimized. Can be processed quickly.

In addition, since the medical simulation system 110 uses a two-color tomographic image obtained by binarizing the medical tomographic image, the medical tomographic image is constituted by tomographic images in three directions of X, Y, and Z that intersect each other. Even if a new one is used, an excessive load is not applied to the computer due to the image processing in the steps after step 2-3, and the image processing can be performed smoothly.

Further, in the above embodiment, each medical tomographic image is classified into two gradations based on the threshold value set with reference to the CT value in the binarization process according to step 2-2, and converted into a two-color tomographic image. Therefore, it is possible to accurately separate into a region including a desired portion and a region including other portions. Therefore, according to the medical simulation system 110 described above, it is possible to accurately acquire a three-dimensional image of a desired part.

In the medical simulation system 110 shown in the above embodiment, if the region is set as the selection region in the two-color tomographic image displayed on the output screen in the region setting step according to step 2-3, the other two colors A portion corresponding to a portion set as a selection region in the tomographic image is also set as a selection region. Similarly, the medical simulation system 110 designates and selects an area (exclusion area) to be excluded from the selection area in the two-color tomographic image displayed on the output screen in the area resetting process according to step 2-7. If the area is reset, the area corresponding to the excluded area in the other two-color tomographic images is also reset as the selected area. Therefore, in the medical simulation system 110, by specifying or resetting an area to be set as a selection area in any two-color tomographic image displayed on the output screen, other two colors Even in the tomographic image, it is possible to reflect the result of area setting and resetting of the selected area, and it is not necessary to perform area setting and resetting of the selected area for each two-color tomographic image. Therefore, according to the medical simulation system 110, it is possible to easily set and reset the selected region without using a doctor or a specialized operator who has experienced operation, and easily and accurately obtain a three-dimensional image of a desired part. It is possible to get to.

In the medical simulation system 110 described above, an X-direction two-color tomographic image group and a Y-direction two-color image created based on a medical tomographic image composed of tomographic images in three directions X, Y, and Z that intersect each other. The tomographic image group and the Z-direction two-color tomographic image group are used for acquiring a medical three-dimensional image in the processes after step 2-3. Therefore, according to the medical simulation system 110 described above, it is possible to set and reset the selected region based on the two-color tomographic image viewed from the three directions of X, Y, and Z, and the medical use with high accuracy. It is possible to easily create a three-dimensional image. In the above-described embodiment, an example in which a medical three-dimensional image is created using a medical tomographic image composed of tomographic images in three directions of X, Y, and Z is illustrated, but the present invention is not limited to this. The medical three-dimensional image may be created based on the tomographic image in any one or two directions of the X, Y, and Z directions.

In the medical simulation system 110 shown in the present embodiment, in the surface formation step (step 2-5), the two-color tomographic image of the region set in the region setting step according to step 2-3 previously performed is obtained. It is possible to form a three-dimensional image (surface image) in combination. Therefore, by referring to the surface image, whether or not an area unnecessary for creating a 3D image is included in the preset area designated as the selection area in the area resetting process according to step 2-7. In addition, it is possible to easily determine and specify at which position an unnecessary region is included in the two-color tomographic image. Therefore, according to the medical simulation system 110 described above, it is possible to improve work efficiency in the region resetting process. In addition, although the example which can implement a surface formation process was illustrated in the said embodiment, this invention is not limited to this, The surface formation process cannot be implemented without having the surface formation means 126. Is possible.

≪About the cutting plate and the manufacturing method of the cutting plate≫
According to the simulation system 20 and the medical simulation system 110 described above, it is possible to simulate the bone correction by osteotomy in advance and appropriately determine the position to perform the osteotomy. In order to perform osteotomy more accurately, the use of surgical instruments that must be handled during the operation, such as the incision and the insertion direction of the bone saw, is taken into account, and the osteotomy position is ensured during the operation. It is preferable to prepare a guide that can be determined appropriately.

If the pre-correction bone model X formed by the simulation system 20 or the medical simulation system 110 described above is used, a three-dimensional model of an osteotomy guide member (hereinafter also referred to as “cutting plate” 150) is constructed. It is possible to form the cutting plate 150 having a minimum size based on the three-dimensional model.

The procedure will be described in detail. First, a pre-correction bone model X corresponding to a bone in a state before correction by osteotomy is formed by the simulation system 20 or the like, and osteotomy is performed in the corrected bone model X. Cut planes a and b indicating the part are set. Thereafter, a model of a cut piece obtained by cutting the pre-correction bone model X at the cutting planes a and b is constructed, and the movement distance of the cut piece required to bring the bone into a normal state and the artificial bone inserted between the cut pieces The shape, size, position for inserting a wire used during the operation (hereinafter also referred to as “wire insertion position”), and the like are determined. When the information on the cutting planes a and b and the wire insertion position is determined in this way, the calculation is performed based on the position information, and the cutting planes a and b and the wire insertion position on the correction bone model X It is derived whether it becomes the position of.

Subsequently, the bone model α (hereinafter also referred to as “expansion model” α) as shown in FIG. 18 and FIG. 19 is constructed by expanding the surface of the pre-correction bone model X by a predetermined thickness t. In FIG. 19, the pre-correction bone model X and the expansion model α are shown in a cylindrical shape for simplification of description. The expanded bone model α is a cylindrical body having a thickness t that is formed along the outer surface of the pre-correction bone model X, and a portion corresponding to the correction bone model X is hollow. The thickness t of the expanded bone model α is set according to the thickness of the cutting plate 150 to be created.

In the expansion model α, when the area δ including the cutting planes a and b and the wire insertion position set as described above is set, a portion corresponding to the area δ is cut out, and the three-dimensional shape of the cutting plate 150 is cut out. A model is built. Cut portions γ1 and γ2 for inserting a cutting tool such as a bone saw are formed at the intersections between the surfaces forming the cutting plate 150 and the cut surfaces a and b. In addition, insertion holes φ (φ1 to φ4 in the drawing) for inserting the wires are formed at the intersections between the normal passing through the wire insertion position and the cutting plate 150.

The cutting plate 150 is formed by modeling using a material such as resin based on the three-dimensional model of the cutting plate 150 obtained by the above-described method. Since the cutting plate 150 formed in this way is formed along the bone to be cut, it is easy to mount at an appropriate position and the bone can be cut at an appropriate position. In addition, according to the above-described method, the cutting plate 150 can be designed while assuming the usage method of the surgical instrument such as a bone saw or wire or the cutting plate 150 that is actually used for the operation at the time of simulation. This preoperative plan can be made more reliable and safe, and as a result, the patient burden can be greatly reduced.

10 Artificial bone for replacement 20 Simulation system (medical simulation system)
22 Bone model acquisition means before correction 24 Reference bone model acquisition means 26 Cutting plane derivation means 28 Vertex setting means 30 Distance derivation means 32 Minimum distance data construction means 34 Maximum distance selection means 36 Start point selection means 38 STL data construction means

Claims

A pre-correction bone model acquisition step of acquiring a bone model representing a bone to be corrected as a pre-correction bone model;
A cutting plane deriving step for deriving cutting planes a and b related to bone fragments A and B formed by cutting and separating the pre-correction bone model;
P vertices A (n) (n is a natural number from 1 to p) are set on the outer periphery of the cut surface a, and q vertices B (m) (m is 1 from the outer periphery of the cut surface b). vertex setting step for setting (natural number of q),
A distance LA (n, m) between one point constituting p vertices A (n) and a part or all of each vertex B (m) is derived, and the derived distance LA (n, m) is derived. Minimum distance for selecting the smallest one and performing minimum distance derivation operation A as minimum distance data LAmin (n, m) for a part or all of p vertices A (n) to construct a minimum distance data group Data group construction process,
A maximum distance selection step of selecting a maximum in a part or all of the data constituting the minimum distance data group;
A starting point selecting step of selecting vertices A (n) and B (m) made by the data selected in the maximum distance selecting step as starting points;
Between the vertices A (n) and B (m) arranged in the circumferential direction of the cut surfaces a and b starting from the vertices A (n) and B (m) selected as the start points, the cut surfaces a and b STL data that constructs STL data that expresses the outer surface of the artificial bone for replacement to be filled in the area between the cutting planes a and b by a plurality of triangle groups by sequentially connecting line segments so as to cross the area between them. A method for forming an artificial bone model for compensation.
A vertex adjacent to the vertex A (n) in the circumferential direction of the cut surface a is a vertex A (n + 1), and a vertex adjacent to the vertex B (m) in the circumferential direction of the cut surface b is a vertex B (m + 1). If
Of the line segment connecting the vertices A (n) and B (m + 1) and the line segment connecting the vertices A (n + 1) and B (m), the line segment with a short distance is selected as the line segment constituting the STL data. The method for forming an artificial bone model for compensation according to claim 1.
The minimum distance data group construction process
In addition to the minimum distance derivation operation A,
A distance LB (n, m) between one point constituting q vertices B (m) and a part or all of each vertex A (n) is derived for each vertex B (m). A minimum distance derivation operation B is performed for some or all of the q vertices B (m) by selecting the smallest one from the distances LB (n, m) and setting the minimum distance LBmin (n, m).
The minimum distance data group is constructed as including the minimum distance data LAmin (n, m) and the minimum distance data LBmin (n, m).
The maximum distance selection process is
Selecting the largest of some or all of the minimum distance data LAmin (n, m) forming the minimum distance data group as the A-side maximum distance data LAmax (n, m);
Selecting the largest of some or all of the minimum distance data LBmin (n, m) forming the minimum distance data group as the B-side maximum distance data LBmax (n, m);
The larger one of the A side maximum distance data LAmax (n, m) and the B side maximum distance data LBmax (n, m) is selected as the maximum distance data Lmax (n, m).
3. The start point selection step is to select vertices A (n) and B (m) forming the maximum distance data Lmax (n, m) as start points, respectively. 3. A method for forming an artificial bone model for filling.
In the pre-correction bone model acquisition step, the pre-correction bone model is acquired by constructing STL data representing the outer surface of the bone to be corrected by a plurality of triangle groups,
In the vertex setting step, the intersections of the sides constituting the triangle group constituting the STL data related to the pre-correction bone model and the cut surfaces a and b are set as vertices A (n) and B (m), respectively. The method for forming an artificial bone model for compensation according to any one of claims 1 to 3.
A reference bone model acquisition step of acquiring a bone model of a healthy bone that is in a plane-symmetrical positional relationship with a bone to be corrected and a plane model that is plane-symmetric, as a reference bone model;
5. The method for forming an artificial bone model for compensation according to claim 1, wherein the cutting planes a and b are determined based on the reference bone model in the cutting plane derivation step.
A method for forming a replacement artificial bone, comprising forming the replacement artificial bone using the STL data obtained by the method for forming a replacement artificial bone model according to any one of claims 1 to 5.
A medical simulation system characterized in that a three-dimensional image of a replacement artificial bone is formed using the method for forming a replacement artificial bone model according to claims 1 to 5.
A binarization step for converting a plurality of medical tomographic images into a two-color tomographic image obtained by forming a two-color image with a threshold set based on a CT value as a boundary;
A region setting step of setting a region corresponding to a selection region set in one of the two-color tomographic images obtained in the binarization step as a selection region in another two-color tomographic image;
In one two-color tomographic image selected from each two-color tomographic image set in the region setting step, a region obtained by excluding a part from the preset region set as a selection region in the region setting step An area resetting step in which the area corresponding to the reset selection area is reset as a selection area in another two-color tomographic image;
A three-dimensional process for forming a three-dimensional image by combining the two-color tomographic images obtained through the region setting step and the region resetting step,
The medical tomographic image is composed of tomographic images in three directions of X, Y, and Z intersecting each other,
Each medical tomographic image forming an X-direction tomographic image group consisting of a tomographic image in the X direction, a Y-directional tomographic image group consisting of a tomographic image in the Y direction, and a Z-directional tomographic image group consisting of a tomographic image in the Z direction. In the binarization step, a two-color image is formed into a two-color tomographic image, and an X-direction two-color tomographic image group, a Y-direction two-color tomographic image group, and a Z-direction two-color tomographic image group are formed,
In the region setting step, in one two-color tomographic image included in one two-color tomographic image group selected from the X-direction two-color tomographic image group, the Y-direction two-color tomographic image group, and the Z-direction two-color tomographic image group. The area corresponding to the selected selection area is the other two-color tomographic image included in the selected two-color tomographic image group, and the two-color tomographic image included in the other two-color tomographic image group that is not selected. The area is set as the selection area in the image,
In the region resetting step, one two-color tomographic image included in one two-color tomographic image group selected from the X-direction two-color tomographic image group, the Y-direction two-color tomographic image group, and the Z-direction two-color tomographic image group In this case, a region excluding a part of the preset region that is set as the selection region is reset as the selection region, and the region corresponding to the reset selection region is selected as the selection region for the other two-color tomographic images. A method for acquiring a medical three-dimensional image, characterized by being reset.
A binarization step for converting a plurality of medical tomographic images into a two-color tomographic image obtained by forming a two-color image with a threshold set based on a CT value as a boundary;
A region setting step of setting a region corresponding to a selection region set in one of the two-color tomographic images obtained in the binarization step as a selection region in another two-color tomographic image;
In one two-color tomographic image selected from each two-color tomographic image set in the region setting step, a region obtained by excluding a part from the preset region set as a selection region in the region setting step An area resetting step in which the area corresponding to the reset selection area is reset as a selection area in another two-color tomographic image;
A three-dimensional process for forming a three-dimensional image by combining the two-color tomographic images obtained through the region setting step and the region resetting step,
A method for acquiring a medical three-dimensional image, comprising: a surface forming step of forming a three-dimensional image by combining two-color tomographic images of regions set in the region setting step.