JP2016168189A - Medical image display device, medical image display method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical image display device capable of reducing time required for the pretreatment for performing separation simulation, and expressing a separation operation for a three-dimensional image.SOLUTION: A medical image display device includes a three-dimensional image output part for displaying a three-dimensional image in a display part, a separation surface designation part for designating a planned separation surface for an image of a separation object included in the three-dimensional image, a mesh model generation part for generating a polyhedron mesh model composed of a plurality of polyhedron elements using the planned separation surface as a reference so that the image of the separation object is included and the density of vertexes of the polyhedron elements is high in an area including the planned separation surface, a separation instruction part for instructing an execution of a separation operation on the planned separation surface, a mesh model deformation part for deforming the polyhedron mesh model according to the separation operation, a three-dimensional image deformation part for deforming the three-dimensional image so as to correspond to the polyhedron mesh model after deformation. A three-dimensional image output part displays the three-dimensional image after deformation in the display part.SELECTED DRAWING: Figure 1

Description

  The present invention creates a three-dimensional medical image (hereinafter referred to as a three-dimensional image) of a specific part of a human body based on a plurality of two-dimensional images photographed by a medical image photographing device such as a CT device or an MRI device. The present invention relates to a displayable medical image display device, a medical image display method, and a program.

  In recent years, as this type of medical image display device, a polygonal image of an object to be separated is designated on the display screen by specifying a planned separation surface, and then the separation object is scheduled to be separated. Development of a device that can observe the state of change when separated on the surface is in progress.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 2014-176425) describes various simulations using polygon images while assuming actual surgery in consideration of the degree of deformation of an organ composed of soft substances such as liver and lung. An apparatus is disclosed that is capable of performing the following.

JP 2014-176425 A

  However, in the apparatus of Patent Document 1, in order to express the deformation of the separation object according to various separation patterns, polygon images corresponding to these various separation patterns are prepared by performing arithmetic processing in advance. It is necessary to keep.

  Further, in the apparatus of Patent Document 1, the object to be separated is displayed as a tetrahedral mesh model that is a set of a plurality of tetrahedral elements, and each tetrahedral element is shown to be deformed by the separation. Is expressed by transforming, dividing, etc. When the structure of the tetrahedron element changes, it takes time to calculate the structure of the tetrahedron element after the change.

  In medical image display devices used for preoperative planning, surgical training simulation, surgical navigation, and the like, it is required to display more precise images. In order to obtain a more precise image, the number of vertices of the tetrahedral mesh model may be increased (for example, several thousand to several tens of thousands). However, when the number of vertices of the tetrahedral mesh model is increased, the time for calculating the deformation of the structure of each tetrahedral element constituting the tetrahedral mesh model also becomes longer.

  For this reason, in order to display more various separation patterns as more detailed images using the apparatus of Patent Document 1, a considerable time (for example, several hours) is required for the calculation process. That is, the apparatus of Patent Document 1 has a problem that it takes a considerable amount of time for preprocessing for performing the separation simulation.

  Further, in the prior art, there is an apparatus that expresses the separation operation for the object to be separated on the polygon image as in the apparatus of Patent Document 1, but the apparatus expresses the separation operation on the three-dimensional image. Did not exist.

  Accordingly, an object of the present invention is to solve the above-described problem, and it is possible to reduce the time required for preprocessing for performing the separation simulation and to express the separation operation on the three-dimensional image. A medical image display device, a medical image display method, and a program are provided.

In order to achieve the above object, the present invention is configured as follows.
According to the present invention, a three-dimensional image data storage unit that stores three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object;
A 3D image output unit for displaying a 3D image on a display unit based on the 3D image data stored in the 3D image data storage unit;
A separation surface designating unit for designating a separation planned surface for the image of the separation object included in the three-dimensional image;
A mesh model generation unit that generates a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit so as to include an image of the separation object; ,
A separation instructing unit for instructing execution of a separation operation on the planned separation surface designated by the separation surface designation unit;
A mesh model deforming unit that deforms the polyhedral mesh model in accordance with the separation operation instructed by the separation instruction unit;
A three-dimensional image deformation unit that deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit;
With
In the mesh model generation unit, the density of the vertices of the polyhedral element is increased in the region including the planned separation surface specified by the separation surface designating unit, while the polyhedron is formed in the region away from the planned separation surface. Generate a polyhedral mesh model so that the density of element vertices is low,
The three-dimensional image output unit displays the three-dimensional image after deformation by the three-dimensional image deformation unit on the display unit;
A medical image display device is provided.

According to the present invention, a medical image is displayed by the three-dimensional image output unit, the separation surface designation unit, the mesh model generation unit, the separation instruction unit, the mesh model deformation unit, and the three-dimensional image deformation unit. A medical image display method to be performed,
The three-dimensional image output unit displays a three-dimensional image on a display unit based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object,
The separation surface designating unit designates a planned separation surface for the image of the separation object included in the three-dimensional image,
The mesh model generation unit includes a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit, and includes an image of the separation object, In the region including the designated planned separation surface, the density of the vertices of the polyhedral element is increased, while in the region separated from the planned separation surface, the vertices of the polyhedral element is generated so as to have a low density.
The separation instruction unit instructs execution of a separation operation on the planned separation surface designated by the separation surface designation unit,
The mesh model deforming unit deforms the polyhedral mesh model according to the instructed separation operation,
The three-dimensional image deformation unit deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit,
The 3D image output unit causes the display unit to display the 3D image after deformation by the 3D image deformation unit;
A medical image display method is provided.

According to the invention, a computer is
A three-dimensional image output unit for displaying a three-dimensional image on a display unit based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object;
A separation surface designating unit for designating a separation planned surface for the image of the separation object included in the three-dimensional image;
A mesh model generation unit that generates a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit so as to include an image of the separation object; ,
A separation instructing unit for instructing execution of a separation operation on the planned separation surface designated by the separation surface designation unit;
A mesh model deforming unit that deforms the polyhedral mesh model in accordance with the separation operation instructed by the separation instruction unit;
A three-dimensional image deformation unit that deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit;
Is a program for functioning as
In the mesh model generation unit, the density of the vertices of the polyhedral element is increased in the region including the planned separation surface specified by the separation surface designating unit, while the polyhedron is formed in the region away from the planned separation surface. Generate a polyhedral mesh model so that the density of element vertices is low,
The three-dimensional image output unit displays the three-dimensional image after deformation by the three-dimensional image deformation unit on the display unit;
Provide a program.

  According to the present invention, it is possible to reduce the time required for the preprocessing for performing the separation simulation and to express the separation operation on the three-dimensional image.

1 is a block diagram illustrating a basic configuration of a medical image display apparatus according to a first embodiment of the present invention. It is an image of the object to be separated displayed on the display unit. It is a figure which shows the example which designated the separation plan surface in the image of the separation object. It is a side view which shows the state which produced | generated the polyhedral mesh model so that the image of the separation target object may be included. It is a perspective view which shows the state which produced | generated the polyhedral mesh model so that the image of the separation target object may be included. It is a figure which shows the polyhedral mesh model produced | generated so that the image of the separation target object may be included. It is a figure which shows the example of arrangement | positioning of the vertex of a polyhedron element in the area | region containing a plane to plan separation. It is a schematic diagram which shows the principle in which a mesh model deformation | transformation part deform | transforms a polyhedral mesh model. It is a schematic diagram which shows the principle in which a mesh model deformation | transformation part deform | transforms a polyhedral mesh model. It is a schematic diagram which shows the principle in which a mesh model deformation | transformation part deform | transforms a polyhedral mesh model. It is a side view which shows the polyhedral mesh model deform | transformed by the mesh model deformation | transformation part. It is a perspective view which shows the polyhedral mesh model deform | transformed by the mesh model deformation | transformation part. FIG. 11 is a side view showing a polyhedral mesh model that is deformed by further proceeding with a separation operation from the state shown in FIGS. 9 and 10. FIG. 11 is a perspective view showing a polyhedral mesh model that has been deformed by further separating operation from the state shown in FIGS. 9 and 10. FIG. 13 is a three-dimensional image corresponding to the polyhedral mesh model shown in FIGS. 9 and 10, and is a diagram illustrating an image of the object to be cut after deformation. FIG. 14 is a three-dimensional image corresponding to the polyhedral mesh model shown in FIGS. 11 and 12, and is a diagram illustrating an image of the object to be cut after deformation. It is a flowchart which shows the medical image display method which concerns on 1st Embodiment of this invention. In the medical image display apparatus according to the second embodiment of the present invention, it is a perspective view showing a state in which a separation surface designation unit has designated a planned separation surface on a three-dimensional screen. In the medical image display apparatus according to the third embodiment of the present invention, the principle of deformation of the tetrahedral mesh model when the separation instructing unit instructs execution of the separation operation at a position slightly deviated from the planned separation surface is shown. It is a schematic diagram. In the medical image display apparatus according to the third embodiment of the present invention, the principle of deformation of the tetrahedral mesh model when the separation instructing unit instructs execution of the separation operation at a position slightly deviated from the planned separation surface is shown. It is a schematic diagram. In the medical image display apparatus which concerns on this 3rd Embodiment, the schematic diagram which shows the principle of a deformation | transformation of a tetrahedral mesh model when the separation instruction | indication part instruct | indicates execution of separation operation in the position slightly shifted from the planned separation surface It is. It is a block diagram which shows the basic composition of the medical image display apparatus which concerns on 4th Embodiment of this invention. It is a schematic diagram which shows the example arrange | positioned so that the density of the vertex of a tetrahedron element may differ in the area | region containing a plane to be cut off.

According to the first aspect of the present invention, a three-dimensional image data storage unit that stores three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object;
A 3D image output unit for displaying a 3D image on a display unit based on the 3D image data stored in the 3D image data storage unit;
A separation surface designating unit for designating a separation planned surface for the image of the separation object included in the three-dimensional image;
A mesh model generation unit that generates a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit so as to include an image of the separation object; ,
A separation instructing unit for instructing execution of a separation operation on the planned separation surface designated by the separation surface designation unit;
A mesh model deforming unit that deforms the polyhedral mesh model in accordance with the separation operation instructed by the separation instruction unit;
A three-dimensional image deformation unit that deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit;
With
In the mesh model generation unit, the density of the vertices of the polyhedral element is increased in the region including the planned separation surface specified by the separation surface designating unit, while the polyhedron is formed in the region away from the planned separation surface. Generate a polyhedral mesh model so that the density of element vertices is low,
The three-dimensional image output unit displays the three-dimensional image after deformation by the three-dimensional image deformation unit on the display unit;
A medical image display device is provided.

  According to the second aspect of the present invention, the mesh model deforming unit applies an external force in a direction in which the portion where the separation is performed by the separation operation is widened as the separation operation progresses, A medical image display device according to a first aspect, which generates a polyhedral mesh model deformed based on an external force.

  According to the third aspect of the present invention, the mesh model deforming unit causes the separation operation to proceed on the vertexes of the polyhedral elements facing each other across the separation execution surface that has been separated by the separation operation. Therefore, the medical image display apparatus according to the first aspect is provided, wherein the polyhedral mesh model is moved so as to be separated from each other and the polyhedral mesh model is deformed so as to correspond to the moved vertex.

  According to the fourth aspect of the present invention, the mesh model generation unit may decrease the number of vertices of the polyhedral element stepwise as the mesh model generation unit moves away from the planned separation surface specified by the separation surface specification unit. A medical image display device according to any one of the first to third aspects, which generates a polyhedral mesh model.

  According to the fifth aspect of the present invention, the separation surface designating unit is configured to be capable of designating at least one separation point on the three-dimensional image, and based on the separation point, the planned separation surface A medical image display device according to any one of the first to fourth aspects is provided.

According to the sixth aspect of the present invention, the separation instructing unit instructs the separation operation on the planned separation surface to be executed in stages,
The separation surface designation unit accepts a change of the planned separation surface during execution of the separation operation,
The mesh model generation unit regenerates the polyhedral mesh model based on the planned separation surface changed by the separation surface designation unit.
A medical image display device according to any one of the first to fifth aspects is provided.

  According to the seventh aspect of the present invention, the mesh model generation unit includes a region having a high density of vertices of the polyhedral element and a region having a low density in the region including the planned separation surface designated by the separation surface designation unit. A medical image display device according to any one of the first to sixth aspects is provided, wherein a polyhedral mesh model is generated so as to occur.

According to the eighth aspect of the present invention, in the region including the planned separation surface designated by the separation surface designation unit, the vertex density capable of designating a region having a high or low vertex density of the polyhedral element. With a designator,
Any one of the first to seventh aspects, wherein the mesh model generation unit generates a polyhedral mesh model so that a region with high and low density of vertices of the polyhedral element is generated based on the specification of the vertex density specifying unit. A medical image display device according to any one of the above is provided.

  According to the ninth aspect of the present invention, the mesh model generation unit fixes the vertices of the polyhedral elements facing each other across the planned separation surface with the planned separation surface, and is separated by the separation instruction unit. The medical image display apparatus according to any one of the first to eighth aspects, which generates a polyhedral mesh model that can be released when the operation is performed.

According to the tenth aspect of the present invention, the three-dimensional image output unit, the separation surface designation unit, the mesh model generation unit, the separation instruction unit, the mesh model deformation unit, and the three-dimensional image deformation unit A medical image display method for displaying an image,
The three-dimensional image output unit displays a three-dimensional image on a display unit based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object,
The separation surface designating unit designates a planned separation surface for the image of the separation object included in the three-dimensional image,
The mesh model generation unit includes a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit, and includes an image of the separation object, In the region including the designated planned separation surface, the density of the vertices of the polyhedral element is increased, while in the region separated from the planned separation surface, the vertices of the polyhedral element is generated so as to have a low density.
The separation instruction unit instructs execution of a separation operation on the planned separation surface designated by the separation surface designation unit,
The mesh model deforming unit deforms the polyhedral mesh model according to the instructed separation operation,
The three-dimensional image deformation unit deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit,
The 3D image output unit causes the display unit to display the 3D image after deformation by the 3D image deformation unit;
A medical image display method is provided.

  According to the eleventh aspect of the present invention, the mesh model deforming unit applies an external force in a direction in which the portion where the separation is performed by the separation operation is widened as the separation operation proceeds. The medical image display method according to the tenth aspect, which generates a polyhedral mesh model deformed based on an external force.

  According to the twelfth aspect of the present invention, the mesh model deforming unit causes the cutting operation to proceed on the apexes of the polyhedral elements facing each other across the cutting execution surface on which the cutting has been performed by the cutting operation. Therefore, the medical image display method according to the tenth aspect is provided, in which the polyhedral mesh model is deformed so as to move away from each other and correspond to the moved vertexes.

  According to the thirteenth aspect of the present invention, the mesh model generation unit is configured such that the number of vertices of the polyhedral element decreases stepwise as the mesh model generation unit moves away from the planned separation surface specified by the separation surface specification unit. The medical image display method according to any one of 10th to 12th aspects, which generates a polyhedral mesh model.

  According to the fourteenth aspect of the present invention, the separation surface designating unit is configured to be capable of designating at least one separation point on the three-dimensional image, and based on the separation point, a planned separation surface The medical image display method according to any one of the tenth to thirteenth aspects is generated or modified.

According to the fifteenth aspect of the present invention, the separation instruction unit instructs the separation operation on the planned separation surface to be executed in stages,
The separation surface designation unit accepts a change of the planned separation surface during execution of the separation operation,
The mesh model generation unit regenerates the polyhedral mesh model based on the planned separation surface changed by the separation surface designation unit.
A medical image display method according to any one of the tenth to fourteenth aspects is provided.

  According to the sixteenth aspect of the present invention, the mesh model generation unit includes a region having a high density of vertices of the polyhedral element and a region having a low density in the region including the planned separation surface specified by the separation surface specifying unit. The medical image display method according to any one of the tenth to fifteenth aspects, wherein the polyhedral mesh model is generated so that the occurrence of the polyhedral mesh model occurs.

  According to the seventeenth aspect of the present invention, the mesh model generation unit fixes vertices of polyhedral elements facing each other across the planned separation surface with the planned separation surface, and is separated by the separation instruction unit. The medical image display method according to any one of the tenth to sixteenth aspects, which generates a polyhedral mesh model that can be released when the operation is performed.

According to an eighteenth aspect of the present invention, a computer
A three-dimensional image output unit for displaying a three-dimensional image on a display unit based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object;
A separation surface designating unit for designating a separation planned surface for the image of the separation object included in the three-dimensional image;
A mesh model generation unit that generates a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit so as to include an image of the separation object; ,
A separation instructing unit for instructing execution of a separation operation on the planned separation surface designated by the separation surface designation unit;
A mesh model deforming unit that deforms the polyhedral mesh model in accordance with the separation operation instructed by the separation instruction unit;
A three-dimensional image deformation unit that deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit;
Is a program for functioning as
In the mesh model generation unit, the density of the vertices of the polyhedral element is increased in the region including the planned separation surface specified by the separation surface designating unit, while the polyhedron is formed in the region away from the planned separation surface. Generate a polyhedral mesh model so that the density of element vertices is low,
The three-dimensional image output unit displays the three-dimensional image after deformation by the three-dimensional image deformation unit on the display unit;
Provide a program.

  According to a nineteenth aspect of the present invention, the mesh model deforming unit applies an external force in a direction in which the part that has been separated by the separation operation is expanded in a direction in which the separation operation progresses. The program according to the eighteenth aspect, which generates a polyhedral mesh model deformed based on an external force.

  According to the twentieth aspect of the present invention, the mesh model deforming unit causes the cutting operation to proceed on the apexes of the polyhedral elements facing each other across the cutting execution surface on which the cutting has been executed by the cutting operation. Therefore, the program according to the eighteenth aspect is provided, wherein the program is moved away from each other and the polyhedral mesh model is deformed so as to correspond to the moved vertex.

  According to a twenty-first aspect of the present invention, the mesh model generation unit is configured so that the number of vertices of the polyhedral element decreases stepwise as the mesh model generation unit moves away from the planned separation surface specified by the separation surface specifying unit. The program as described in any one of the 18th-20th aspect which produces | generates a polyhedral mesh model is provided.

  According to the twenty-second aspect of the present invention, the separation surface designation unit is configured to be capable of designating at least one separation point on the three-dimensional image, and based on the separation point, A program according to any one of the eighteenth to twenty-first aspects is provided.

According to the twenty-third aspect of the present invention, the separation instructing unit instructs the separation operation on the planned separation surface to be executed in stages,
The separation surface designation unit accepts a change of the planned separation surface during execution of the separation operation,
The mesh model generation unit regenerates the polyhedral mesh model based on the planned separation surface changed by the separation surface designation unit.
A program according to any one of the 18th to 22nd aspects is provided.

  According to the twenty-fourth aspect of the present invention, the mesh model generation unit includes a region having a high density of vertices of the polyhedral element and a region having a low density in the region including the planned separation surface designated by the separation surface designation unit. A program according to any one of the eighteenth to twenty-third aspects, which generates a polyhedral mesh model so as to occur.

  According to a twenty-fifth aspect of the present invention, the mesh model generation unit fixes vertices of polyhedral elements facing each other across the planned separation surface with the planned separation surface, and is separated by the separation instruction unit. A program according to any one of the eighteenth to twenty-fourth aspects, which generates a polyhedral mesh model capable of releasing the fixation when an operation is executed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

<< First Embodiment >>
FIG. 1 is a block diagram showing a basic configuration of a medical image display apparatus according to the first embodiment of the present invention.

  The medical image display apparatus 1 according to the first embodiment creates and displays a three-dimensional image of an object to be cut based on a plurality of two-dimensional images photographed by a medical image photographing apparatus such as a CT apparatus or an MRI apparatus. It is a possible device. The medical image display apparatus 1 is an apparatus that enables observation of the state of change when the separation object is separated in accordance with the separation operation performed by the user on the image of the separation object. is there. The medical image display device 1 can be used for medical applications such as preoperative planning, surgical training simulation, and surgical navigation.

  As shown in FIG. 1, an input unit 2 that inputs various information to the medical image display device 1 is connected to the medical image display device 1. The input unit 2 is input means such as a keyboard, a mouse, a numeric keypad, and a menu screen. The input unit 2 can be realized by a device driver for input means such as a keyboard, control software for a menu screen, or the like.

  The medical image display device 1 is connected to a display unit 3 that displays a three-dimensional image based on the output from the medical image display device 1. The display unit 3 is, for example, a display unit such as a PC (personal computer) display or a projector.

  As shown in FIG. 1, the medical image display device 1 includes a 3D image data storage unit 11, a 3D image output unit 12, a separation plane designation unit 13, a mesh model generation unit 14, and a separation instruction unit 15. And a mesh model deforming unit 16 and a three-dimensional image deforming unit 17.

  The three-dimensional image data storage unit 11 stores three-dimensional image data (volume data) obtained from a plurality of two-dimensional images obtained by capturing an object to be separated. The “separation target” is a specific part of the human body, such as the liver or lung. The three-dimensional image data storage unit 11 is realized by a storage medium built in the PC, for example.

  The 3D image output unit 12 displays a 3D image (for example, a volume rendering image) on the display unit 3 based on the 3D image data stored in the 3D image data storage unit 11. FIG. 2 shows an image 31 of the object to be cut (liver) displayed on the display unit 3. The timing at which the 3D image output unit 12 displays the 3D image on the display unit 3 is based on, for example, an instruction to display a 3D image from the input unit 2.

  As shown in FIG. 3, the separation plane designating unit 13 designates a planned separation plane 32 for the image 31 of the separation target included in the three-dimensional image displayed on the display unit 3. The designation of the planned separation surface 32 by the separation surface designating unit 13 is performed based on an instruction to designate the planned separation surface from the input unit 2 such as, for example, moving the mouse and clicking.

  As shown in FIGS. 4 and 5, the mesh model generation unit 14 has a tetrahedral mesh model 33 composed of a plurality of tetrahedral elements based on the planned separation surface 32 designated by the separation surface designation unit 13. Is generated so as to include the image 31 of the separation object. In the first embodiment, the mesh model generation unit 14 fixes the vertices of the polyhedron elements facing each other across the planned separation surface 32 with the planned separation surface 32, and executes the separation operation by the separation instruction unit 15. A tetrahedral mesh model that can be released from time to time is generated. 4 and 5 and FIGS. 9 to 12 to be described later, illustration of blood vessels and the like existing inside the object to be cut is omitted for easy understanding of the drawings.

  Further, as shown in FIGS. 6 and 7, the mesh model generation unit 14 increases the density of the vertices of the tetrahedron elements in the region E1 including the planned separation surface 31 specified by the separation surface specifying unit 13. Thus, the tetrahedral mesh model 33 is generated. On the other hand, the mesh model generation unit 14 generates the tetrahedral mesh model 33 so that the density of the vertices of the tetrahedral elements is low in the regions E2 to E7 away from the planned separation surface 31. For example, in the example of the tetrahedral mesh model 33 shown in FIGS. 4 to 6, the number of vertices of the tetrahedron element is set to region E1: 127 points, region E2, E5: 37 points, regions E3, E4, E6, E7. : 7 points. That is, the mesh model generation unit 14 generates the tetrahedral mesh model 33 so that the number of vertices of the tetrahedral element gradually decreases as the distance from the planned separation surface 31 specified by the separation surface specification unit 13 increases. To do.

  Here, it means that “there is no area where the number of vertices of the tetrahedron element increases as the distance from the planned separation surface 31 increases.” As in the areas E3, E4, E6, E7, the tetrahedron There may be regions where the number of vertices of the element is the same.

  The separation instructing unit 15 instructs the execution of the separation operation on the planned separation surface 32 specified by the separation surface specifying unit 13. In the first embodiment, in accordance with the instruction, the fixing of the apexes of the polyhedral elements facing each other across the planned separation surface 32 of the tetrahedral mesh model is released. The separation operation performed by the separation instruction unit 15 is performed based on an instruction for performing the separation operation from the input unit 2 such as, for example, double-clicking the mouse or pressing an enter key.

  The mesh model deformation unit 16 deforms the tetrahedral mesh model in accordance with the separation operation instructed by the separation instruction unit 15. 8A to 8C are schematic diagrams illustrating the principle by which the mesh model deforming unit 16 deforms the tetrahedral mesh model.

  The mesh model deforming unit 16 applies an external force in a direction in which the part that has been separated by the separation operation is expanded in accordance with the progress of the separation operation, and deforms the tetrahedral mesh model based on the given external force. 33 is generated. In the first embodiment, the mesh model deforming unit 16 expands as the separation operation proceeds with respect to the portion where the vertices of the polyhedral elements facing each other across the planned separation surface 32 are released. A tetrahedral mesh model 33 deformed based on the applied external force is generated. The mesh model deforming unit 16 moves the vertices of the tetrahedral elements facing each other across the separation execution surface 34 that has been separated by the separation operation so as to separate from each other as the separation operation proceeds, The tetrahedral mesh model 33 may be deformed so as to correspond to the moved vertex.

  9 is a side view showing the tetrahedral mesh model 33A deformed by the mesh model deforming unit 16, and FIG. 10 is a perspective view thereof. FIG. 11 is a side view showing a tetrahedral mesh model 33B that has been deformed by further separating operation from the state shown in FIGS. 9 and 10, and FIG. 12 is a perspective view thereof.

  The three-dimensional image deformation unit 17 deforms the three-dimensional image so as to correspond to the tetrahedral mesh model after deformation by the mesh model deformation unit 16. In other words, the three-dimensional image deformation unit 17 generates a deformed three-dimensional image by complementing the inside of the tetrahedral mesh model deformed by the mesh model deformation unit 16 with the three-dimensional image.

  FIG. 13 is a three-dimensional image corresponding to the tetrahedral mesh model 33A shown in FIGS. 9 and 10, and is a diagram showing an image 31A of the separation object after deformation. FIG. 14 is a three-dimensional image corresponding to the tetrahedral mesh model 33B shown in FIGS. 11 and 12, and is a diagram showing an image 31B of the object to be cut after deformation.

  The images 31A and 31B of the separation object deformed by the three-dimensional image deformation unit 17 are displayed on the display unit 3 by the three-dimensional image output unit 12. Thereby, the user can observe the state of change when the separation object is separated.

  Note that the 3D image output unit 12, the separation surface designation unit 13, the mesh model generation unit 14, the separation instruction unit 15, the mesh model deformation unit 16, and the 3D image deformation unit 17 are, for example, an MPU or a memory. It is feasible. Moreover, the processing procedure of each part 12-16 is realizable with the software and hardware (dedicated circuit) which are recorded on storage media, such as ROM, for example.

  Note that the deformation process of the tetrahedral mesh model 33 by the mesh model deformation unit 16 and the deformation process of the 3D image by the 3D image deformation unit 17 can be performed by a conventionally known technique. Omitted.

  In the first embodiment, the mesh model generated by the mesh model generating unit 14 and the mesh model deformed by the mesh model deforming unit 16 are tetrahedral mesh models composed of tetrahedral elements. Is not limited to this. The mesh model may be a hexahedral mesh model composed of hexahedral elements. That is, the mesh model may be a polyhedral mesh model composed of polyhedral elements. This also applies to other embodiments in this specification.

  In the first embodiment, the input unit 2 and the display unit 3 are provided separately from the medical image display device 1, but the present invention is not limited to this. For example, one or both of the input unit 2 and the display unit 3 may be included in the medical image display device 1.

  Next, a medical image display method using the medical image display device 1 will be described.

  FIG. 15 is a flowchart showing a medical image display method according to the first embodiment of the present invention. Here, the description is started assuming that 3D image data obtained from a plurality of 2D images obtained by imaging the object to be cut is stored in the 3D image data storage unit 11 in advance.

  First, the three-dimensional image output unit 12 performs a three-dimensional image based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging the object to be cut based on a three-dimensional image display instruction from the input unit 2. Is displayed on the display unit 3 (step S1, see FIG. 2).

  Next, the separation surface designating unit 13 designates the planned separation surface 32 for the image 31 of the separation object included in the three-dimensional image based on the instruction to designate the planned separation surface from the input unit 2. (See step S2, FIG. 3). While the scheduled separation surface 32 is not designated by the separation surface designation unit 13 ("N" in step S2), the standby state is entered. When the designation is made ("Y" in step S2), the next step S3 is performed. move on.

  Next, the mesh model generation unit 14 converts the tetrahedral mesh model 33 composed of a plurality of tetrahedral elements into the image of the object to be separated in accordance with the planned separation surface 32 designated by the separation surface designation unit 13. It is generated so as to contain. In the first embodiment, the mesh model generation unit 14 fixes the apexes of the polyhedron elements facing each other across the planned separation surface 32 with the planned separation surface 32, and performs the separation operation by the separation instruction unit 15. A tetrahedral mesh model that can release the fixation at the time of execution is generated. At this time, the mesh model generation unit 14 increases the density of the vertices of the tetrahedron elements in the region E1 including the designated planned separation surface, while in the regions E2 to E7 away from the planned separation surface. Generates a tetrahedral mesh model 33 so that the density of the vertices of the tetrahedral elements is low (see step S3, FIGS. 4 to 7).

  Next, the separation instructing unit 15 instructs the execution of the separation operation on the planned separation surface 32 specified by the separation surface designating unit 13 based on the instruction to perform the separation operation from the input unit 2 ( Step S4). In the first embodiment, in accordance with the instruction, the fixing of the apexes of the polyhedral elements facing each other across the planned separation surface 32 of the tetrahedral mesh model is released. While the separation instruction unit 15 is not instructed to perform the separation operation (“Y” in step S4), the standby state is entered. When the designation is made (“N” in step S4), the process proceeds to the next step S5.

  Next, the mesh model deforming unit 16 deforms the tetrahedral mesh model 33 in accordance with the separation operation instructed by the separation instructing unit 15 (see step S5, FIG. 8A to FIG. 12). In the first embodiment, the mesh model deforming unit 16 expands the portion where the fixing of the vertices of the polyhedron elements facing each other across the planned separation surface 32 is released as the separation operation proceeds. An external force is applied in the direction, and a tetrahedral mesh model 33 deformed based on the applied external force is generated.

  Next, the 3D image deforming unit 17 deforms the 3D image so as to correspond to the tetrahedral mesh model deformed by the mesh model deforming unit 16 (step S6).

  Next, the three-dimensional image output unit 18 causes the display unit 3 to display the three-dimensional image after the deformation by the three-dimensional image deformation unit 17 (see step S7, FIG. 13 and FIG. 14). Thereby, the user can observe the mode of change when the separation object is separated.

  According to the first embodiment, both the tetrahedral mesh model and the three-dimensional image are used, the deformation accompanying the separation is performed based on the tetrahedral mesh model, and the three-dimensional based on the deformed tetrahedral mesh model. The image is deformed and the deformed three-dimensional image is displayed. That is, the calculation process by the deformation accompanying the separation is performed on the tetrahedral mesh model, while a three-dimensional image is displayed on the display unit. Thereby, the separation operation for the separation object can be expressed on the three-dimensional image.

  According to the first embodiment, since the tetrahedral mesh model is generated according to the planned separation surface specified by the separation surface designating unit, the tetrahedral element is divided before the separation operation. There is no need to perform the operation, and the calculation processing time for that can be eliminated. Therefore, the time required for the preprocessing for performing the separation simulation can be significantly shortened.

  Further, according to the first embodiment, the density of the vertices of the tetrahedral element is increased in the region E1 including the planned separation surface. As a result, the vicinity of the planned separation surface where the user's attention is gathered can be expressed by a precise three-dimensional image with less distortion.

  Further, according to the first embodiment, the density of the vertices of the tetrahedron elements is lowered in the regions E2 to E7 separated from the planned separation surface. As a result, the number of vertices of the tetrahedral element can be reduced, and the time for calculating the deformation of the tetrahedral mesh model can be shortened.

  According to the first embodiment, since the tetrahedral mesh model is not used to display the image of the object to be separated, the tetrahedral mesh model has a very rough structure with few vertices. Can do. For example, the number of vertices of the tetrahedral mesh model can be about several hundreds. Thereby, it is possible to greatly shorten the time for calculating the deformation of the tetrahedral mesh model.

  In addition, according to the first embodiment, the tetrahedral mesh model is generated so that the number of vertices of the tetrahedral element gradually decreases as the distance from the planned separation surface specified by the separation surface designating unit increases. I am doing so. Thereby, it can suppress that the shape of a tetrahedral element leaves | separates from a regular tetrahedron, and can suppress that calculation accuracy falls.

  Further, according to the first embodiment, the time required for the preprocessing for performing the separation simulation and the time for calculating the deformation of the tetrahedral mesh model can be significantly shortened. It is possible to display a high-speed separation operation. That is, the separation simulation can be shown in real time.

  Note that the function of each unit of the medical image display apparatus according to the first embodiment may be realized by software. The software may be provided by downloading or the like. The software may be provided by being recorded on a storage medium such as a CD-ROM. This also applies to other embodiments in this specification. The software that realizes the medical image display apparatus 1 according to the first embodiment is the following program. That is, the program includes a three-dimensional image output unit that causes a computer to display a three-dimensional image on a display unit based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by capturing an object to be cut, and a three-dimensional image. It consists of multiple polyhedron elements based on the separation plane designating part that specifies the planned separation surface for the image of the object to be separated contained in and the planned separation surface specified by the separation surface designating part. A mesh model generation unit that generates a polyhedral mesh model that includes the image of the object to be separated, and a separation that instructs execution of the separation operation on the planned separation surface specified by the separation surface designation unit An instructing unit, a mesh model deforming unit that deforms the polyhedral mesh model according to the separation operation instructed by the separation instructing unit, and a three-dimensional image corresponding to the polyhedral mesh model after deformation by the mesh model deforming unit Strange The mesh model generation unit increases the density of the vertices of the polyhedron element in the region including the planned separation surface designated by the separation surface designation unit. On the other hand, a polyhedral mesh model is generated so that the density of the vertices of the polyhedron element is low in the area away from the plane to be separated, and the 3D image output unit 3D A program for displaying an image on the display unit.

<< Second Embodiment >>
A medical image display apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 16 is a perspective view showing a state in which the separation surface designation unit designates a planned separation surface on the three-dimensional screen in the medical image display apparatus according to the second embodiment of the present invention.

  The second embodiment is different from the first embodiment in that the separation plane designating unit 13 is configured so that at least one separation point 35 can be designated on the three-dimensional image. It is a point which produces | generates or changes the separation plan surface 32 based on. The designation of the planned separation surface 32 by the separation surface designating unit 13 is performed based on an instruction to designate the planned separation surface from the input unit 2 such as, for example, moving the mouse and clicking.

  According to the second embodiment, when the user inputs the separation point 35 through the input unit 2, the separation surface designating unit 13 generates or changes the planned separation surface 32 so as to pass through the separation point. To do. That is, the user can perform the separation operation by changing the shape of the planned separation surface 32 to an arbitrary shape that is not limited to a flat surface or a curved surface.

<< Third Embodiment >>
A medical image display apparatus according to a third embodiment of the present invention will be described with reference to FIGS. 17A to 17C. FIGS. 17A to 17C illustrate a tetrahedral mesh model when the separation instruction unit instructs execution of the separation operation at a position slightly deviated from the planned separation surface in the medical image display apparatus according to the third embodiment. It is a schematic diagram which shows the principle of a deformation | transformation.

  The third embodiment is different from the first or second embodiment in that the separation instructing unit 15 is configured to be able to execute a separation operation at a position slightly deviated from the planned separation surface 32 and generate a mesh model. The part 14 is a point which produces | generates or deform | transforms a tetrahedral mesh model according to the said separation operation. The instruction to perform the separation operation by the separation instruction unit 15 is performed based on an instruction to perform the separation operation from the input unit 2 such as dragging a mouse.

  For example, as shown in FIG. 17A, it is assumed that the separation instructing unit 15 instructs the execution of the separation operation at a position 36 slightly deviated from the planned separation surface 32. In this case, as illustrated in FIG. 17B, the mesh model generation unit 14 generates (or updates) the tetrahedral mesh model by moving (updating) the vertex of the tetrahedral mesh model along the position 36. As shown in FIG. 17C, the mesh model deforming unit 16 deforms the deformed tetrahedral mesh model in accordance with the separation operation instructed by the separation instructing unit 13.

  According to the third embodiment, it is not necessary to divide the tetrahedron elements, and it is possible to eliminate the calculation processing time for that.

  Note that the separation instructing unit 15 instructs the separation operation on the planned separation surface 32 to be executed in stages, and the separation surface designating unit 13 sets the separation surface 32 while the separation operation is being performed. The change may be received, and the mesh model generation unit 14 may be configured to regenerate the tetrahedral mesh model based on the planned separation surface 32 changed by the separation surface designation unit 13. That is, the tetrahedral mesh model may be regenerated in accordance with the separation operation by the separation instruction unit 15. According to this configuration, for example, a tetrahedral mesh model is generated or deformed almost in real time by dragging the mouse while crossing the object to be separated, and the state of separation of the object to be separated is displayed on the display unit. It can be displayed as a three-dimensional image.

<< 4th Embodiment >>
FIG. 18 is a block diagram showing a basic configuration of a medical image display apparatus according to the fourth embodiment of the present invention.

  The fourth embodiment is different from the first to third embodiments in that a vertex density specifying unit 18 is provided.

  As shown in FIG. 19, the vertex density designating unit 18 designates a region where the density of vertices of the tetrahedral element is high or low in the region E1 including the planned separation surface 32 designated by the separation surface designating unit 13. It is configured to be possible. The apex density designation by the apex density designation unit 18 is performed based on an apex density designation instruction from the input unit 2 such as, for example, moving the mouse on the planned separation surface 32 and clicking.

  In the fourth embodiment, the mesh model generation unit 14 generates a tetrahedral mesh model based on the designation of the vertex density designation unit 18 so that a region where the density of the vertices of the tetrahedral element is high and a region where the density is low are generated. .

  According to the fourth embodiment, in the region E1 including the planned separation surface 32, when there is a region to be observed particularly in a precise three-dimensional image with little distortion, the density of the vertices of the tetrahedral elements in the region is set. The 3D image can be obtained by increasing the height.

  According to the fourth embodiment, when there is a region in the planned separation surface 32 that has no problem even if there is distortion of the three-dimensional image, the density of the vertices of the tetrahedral elements in the region is reduced. By reducing the number of the vertices, it is possible to shorten the time for calculating the deformation of the tetrahedral mesh model.

  In the fourth embodiment, the vertex density designation unit 18 varies the densities of the vertices of the tetrahedron elements in the region E1, but the present invention is not limited to this. For example, the mesh model generation unit 14 may generate a tetrahedral mesh model based on a predetermined pattern in which the density of the vertices of the tetrahedral elements on the planned separation surface 32 is different. In this case, it is not necessary to provide the vertex density specifying unit 18.

  It is to be noted that, by appropriately combining any of the various embodiments, the effects possessed by them can be produced.

  While the invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included therein, so long as they do not depart from the scope of the present invention according to the appended claims.

  The present invention shortens the time required for the preprocessing for performing the separation simulation and can express the separation operation with respect to the three-dimensional image. For example, preoperative planning, surgical training simulation, surgical navigation can be performed. It is useful for applications in the medical field.

DESCRIPTION OF SYMBOLS 1 Medical image display apparatus 2 Input part 3 Display part 11 3D image data memory | storage part 12 3D image output part 13 Separation surface designation | designated part 14 Mesh model production | generation part 15 Separation instruction | indication part 16 Mesh model deformation | transformation part 17 3D image deformation | transformation Section 18 Vertex density designation section 31 Image of object to be separated 32 Planned separation surface 33 Tetrahedral mesh model 34 Separation execution surface 35 Separation point 36 Position E1 to E7 area

Claims (25)

A three-dimensional image data storage unit for storing three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object;
A 3D image output unit for displaying a 3D image on a display unit based on the 3D image data stored in the 3D image data storage unit;
A separation surface designating unit for designating a separation planned surface for the image of the separation object included in the three-dimensional image;
A mesh model generation unit that generates a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit so as to include an image of the separation object; ,
A separation instructing unit for instructing execution of a separation operation on the planned separation surface designated by the separation surface designation unit;
A mesh model deforming unit that deforms the polyhedral mesh model in accordance with the separation operation instructed by the separation instruction unit;
A three-dimensional image deformation unit that deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit;
With
In the mesh model generation unit, the density of the vertices of the polyhedral element is increased in the region including the planned separation surface specified by the separation surface designating unit, while the polyhedron is formed in the region away from the planned separation surface. Generate a polyhedral mesh model so that the density of element vertices is low,
The three-dimensional image output unit displays the three-dimensional image after deformation by the three-dimensional image deformation unit on the display unit;
Medical image display device.   The mesh model deforming unit is configured to apply an external force in a direction in which a part that has been separated by the separation operation is expanded as the separation operation proceeds, and deform the polyhedral mesh model based on the applied external force. The medical image display device according to claim 1, wherein   The mesh model deforming unit moves the vertices of the polyhedral elements facing each other across the separation execution surface that has been separated by the separation operation so as to move away from each other as the separation operation proceeds, and the movement The medical image display apparatus according to claim 1, wherein the polyhedral mesh model is deformed so as to correspond to the vertexes that have been made.   The mesh model generation unit generates a polyhedral mesh model such that the number of vertices of the polyhedral element decreases stepwise as the distance from the planned separation surface specified by the separation surface specification unit increases. The medical image display apparatus as described in any one of -3.   The separation surface designating unit is configured to be capable of designating at least one separation point on the three-dimensional image, and generates or changes a planned separation surface based on the separation point. 5. The medical image display device according to any one of 4. The separation instructing unit instructs the separation operation on the planned separation surface to be executed in stages,
The separation surface designation unit accepts a change of the planned separation surface during execution of the separation operation,
The mesh model generation unit regenerates the polyhedral mesh model based on the planned separation surface changed by the separation surface designation unit.
The medical image display apparatus according to any one of claims 1 to 5.   The mesh model generation unit generates a polyhedral mesh model so that a region having a high density and a low region of vertices of the polyhedral element are generated in a region including a planned separation surface specified by the separation surface specifying unit. The medical image display apparatus according to any one of claims 1 to 6. Furthermore, in a region including the planned separation surface designated by the separation surface designating unit, a vertex density designating unit capable of designating a region having a high or low vertex density of the polyhedral element,
The mesh model generation unit generates a polyhedral mesh model based on the designation of the vertex density designation unit so that a region with a high density and a region with a low density of vertices of the polyhedral element are generated. The medical image display apparatus as described in any one.   The mesh model generation unit can fix vertices of polyhedral elements facing each other across the planned separation surface with the planned separation surface, and can release the fixation when the separation instruction unit performs the separation operation. The medical image display apparatus according to claim 1, which generates a polyhedral mesh model. A medical image display method in which a medical image is displayed by a three-dimensional image output unit, a separation surface designation unit, a mesh model generation unit, a separation instruction unit, a mesh model deformation unit, and a three-dimensional image deformation unit. There,
The three-dimensional image output unit displays a three-dimensional image on a display unit based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object,
The separation surface designating unit designates a planned separation surface for the image of the separation object included in the three-dimensional image,
The mesh model generation unit includes a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit, and includes an image of the separation object, In the region including the designated planned separation surface, the density of the vertices of the polyhedral element is increased, while in the region separated from the planned separation surface, the vertices of the polyhedral element is generated so as to have a low density.
The separation instruction unit instructs execution of a separation operation on the planned separation surface designated by the separation surface designation unit,
The mesh model deforming unit deforms the polyhedral mesh model according to the instructed separation operation,
The three-dimensional image deformation unit deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit,
The 3D image output unit causes the display unit to display the 3D image after deformation by the 3D image deformation unit;
Medical image display method.   The mesh model deforming unit is configured to apply an external force in a direction in which a part that has been separated by the separation operation is expanded as the separation operation proceeds, and deform the polyhedral mesh model based on the applied external force. The medical image display method according to claim 10, wherein:   The mesh model deforming unit moves the vertices of the polyhedral elements facing each other across the separation execution surface that has been separated by the separation operation so as to move away from each other as the separation operation proceeds, and the movement The medical image display method according to claim 10, wherein the polyhedral mesh model is deformed so as to correspond to the apexes.   The said mesh model production | generation part produces | generates a polyhedral mesh model so that the score of the vertex of the said polyhedral element may decrease in steps as it leaves | separates from the planned separation surface specified by the said separation surface designation | designated part. The medical image display method as described in any one of -12.   The separation surface designating unit is configured to be capable of designating at least one separation point on the three-dimensional image, and generates or changes a planned separation surface based on the separation point. 14. The medical image display method according to any one of 13. The separation instructing unit instructs the separation operation on the planned separation surface to be executed in stages,
The separation surface designation unit accepts a change of the planned separation surface during execution of the separation operation,
The mesh model generation unit regenerates the polyhedral mesh model based on the planned separation surface changed by the separation surface designation unit.
The medical image display method according to any one of claims 10 to 14.   The mesh model generation unit generates a polyhedral mesh model so that a region having a high density and a low region of vertices of the polyhedral element are generated in a region including a planned separation surface specified by the separation surface specifying unit. The medical image display method according to any one of claims 10 to 15.   The mesh model generation unit can fix vertices of polyhedral elements facing each other across the planned separation surface with the planned separation surface, and can release the fixation when the separation instruction unit performs the separation operation. The medical image display method according to claim 10, wherein a polyhedral mesh model is generated. Computer
A three-dimensional image output unit for displaying a three-dimensional image on a display unit based on three-dimensional image data obtained from a plurality of two-dimensional images obtained by imaging a separation object;
A separation surface designating unit for designating a separation planned surface for the image of the separation object included in the three-dimensional image;
A mesh model generation unit that generates a polyhedral mesh model composed of a plurality of polyhedral elements based on the planned separation surface designated by the separation surface designation unit so as to include an image of the separation object; ,
A separation instructing unit for instructing execution of a separation operation on the planned separation surface designated by the separation surface designation unit;
A mesh model deforming unit that deforms the polyhedral mesh model in accordance with the separation operation instructed by the separation instruction unit;
A three-dimensional image deformation unit that deforms the three-dimensional image so as to correspond to the polyhedral mesh model after deformation by the mesh model deformation unit;
Is a program for functioning as
In the mesh model generation unit, the density of the vertices of the polyhedral element is increased in the region including the planned separation surface specified by the separation surface designating unit, while the polyhedron is formed in the region away from the planned separation surface. Generate a polyhedral mesh model so that the density of element vertices is low,
The three-dimensional image output unit displays the three-dimensional image after deformation by the three-dimensional image deformation unit on the display unit;
program.   The mesh model deforming unit is configured to apply an external force in a direction in which a part that has been separated by the separation operation is expanded as the separation operation proceeds, and deform the polyhedral mesh model based on the applied external force. The program of Claim 18 which produces | generates.   The mesh model deforming unit moves the vertices of the polyhedral elements facing each other across the separation execution surface that has been separated by the separation operation so as to move away from each other as the separation operation proceeds, and the movement The program according to claim 18, wherein the polyhedral mesh model is deformed so as to correspond to the vertices.   The mesh model generation unit generates the polyhedral mesh model so that the number of vertices of the polyhedral element decreases stepwise as the distance from the planned separation surface specified by the separation surface specification unit increases. The program according to any one of -20.   The separation surface designating unit is configured to be capable of designating at least one separation point on the three-dimensional image, and generates or changes a planned separation surface based on the separation point. 21. The program according to any one of 21. The separation instructing unit instructs the separation operation on the planned separation surface to be executed in stages,
The separation surface designation unit accepts a change of the planned separation surface during execution of the separation operation,
The mesh model generation unit regenerates the polyhedral mesh model based on the planned separation surface changed by the separation surface designation unit.
The program according to any one of claims 18 to 22.   The mesh model generation unit generates a polyhedral mesh model so that a region having a high density and a low region of vertices of the polyhedral element are generated in a region including a planned separation surface specified by the separation surface specifying unit. The program according to any one of claims 18 to 23.   The mesh model generation unit can fix vertices of polyhedral elements facing each other across the planned separation surface with the planned separation surface, and can release the fixation when the separation instruction unit performs the separation operation. The program according to any one of claims 18 to 24, which generates a polyhedral mesh model.