JP3641788B2 - 3D image construction method - Google Patents

Description

[0001]
[Industrial application fields]
In the present invention, for example, a plurality of surface three-dimensional images such as stomach and liver are combined to form a combined three-dimensional image, or one or two or more arbitrarily selected from the combined three-dimensional image The present invention relates to a method for constructing a three-dimensional image capable of deleting only the surface three-dimensional image, for example, the surface three-dimensional image of the stomach.
[0002]
[Prior art]
In recent years, a plurality of CT images are stacked to obtain a stacked three-dimensional image, and a two-dimensional image viewed from an arbitrary direction is shaded by a depth method to form a three-dimensional image (depth image). A three-dimensional image (surface three-dimensional image) converted using the surface method has come to be used in the planning stage before diagnosis and surgery.
[0003]
Here, the depth method is a method of applying a shadow according to the distance from each pixel on the CT image to a location where the pixel is projected. Usually, the longer the distance, the darker the shadow. The surface method is a method of imaging a density gradient. Usually, the pixel value is increased (lightened) when the density gradient is small, and the pixel value is decreased (darkened) when the density gradient is large.
[0004]
If such a three-dimensional image (surface three-dimensional image) is included in a stacked three-dimensional image of a series of CT images, not only one part, for example, the stomach, but any part thereof, for example, the liver, intestine, etc. In recent years, it has become possible to simultaneously display a plurality of surface three-dimensional images.
[0005]
Conventionally, however, when 3D images of the stomach, liver, etc. are extracted, they are treated as the same extracted data without distinguishing between the 3D images so that they can only be distinguished visually when they are displayed simultaneously. It was that. That is, conventionally, when a selected portion, for example, the stomach and liver, included in the stacked three-dimensional image of a series of CT images is extracted as three-dimensional image data, the stomach and liver are always displayed simultaneously. Alternatively, a single surface three-dimensional image of the stomach or liver extracted individually is displayed separately.
[0006]
[Problems to be solved by the invention]
Therefore, for example, it is instructed to remove only the stomach surface 3D image from the combined 3D image in which the stomach and liver surface 3D images are displayed at the same time, and only the liver surface 3D image is left (displayed). ) Could not be said. However, the synthesis of such a surface 3D image and the deletion of some of the surface 3D images are extremely useful, for example, for diagnosis on an image workstation and simulation before surgery. Was requested.
[0007]
The object of the present invention has been made in view of the above-mentioned demand, and not only can a plurality of surface three-dimensional images be combined to form a single combined three-dimensional image, but also a combined three-dimensional image that is formed, that is, simultaneously. Three-dimensional image in which one or more desired surface three-dimensional images can be retained by removing one or more desired surface three-dimensional images from a plurality of surface three-dimensional images displayed, particularly overlapping A configuration method is provided.
[0008]
[Means for Solving the Problems]
The purpose is to stack a plurality of CT images to obtain a stacked three-dimensional image, which is shaded by a depth method for each of a plurality of desired two-dimensional images viewed from an arbitrary direction. In the method for constructing a three-dimensional image, a depth image is obtained and a plurality of surface three-dimensional images obtained by converting each depth image using a surface method are combined to form a single composite three-dimensional image. Among the pixel values of the pixels at the same position of the plurality of surface three-dimensional images, the pixel value of the pixel of the surface three-dimensional image located at the closest distance to the projection surface of the composite three-dimensional image is used as the composite three-dimensional image. The combined three-dimensional image is formed by selecting and assigning the pixel values of the pixels constituting the image, and at the same time, each pixel position of the combined three-dimensional image and the pixel value at the pixel position are selected. A composite 3D image construction method in which the identification symbol of the Ace 3D image is recorded in the display identification map, and an arbitrarily designated pixel position in the composite 3D image constructed by the composite 3D image construction method. The surface three-dimensional image to be deleted is determined with reference to the corresponding pixel position of the display identification map, and the remaining all surface three-dimensional images excluding the surface three-dimensional image are used. This is achieved by providing a three-dimensional image deletion method for deleting a desired surface three-dimensional image in the composite three-dimensional image by constructing a new composite three-dimensional image.
[0009]
[Action]
In the composite 3D image construction method, when composing a composite 3D image, at the same time, each pixel position of the composite 3D image and an identification symbol of the surface 3D image in which the pixel value of the pixel position is selected are displayed. Record in the identification map.
[0010]
In the three-dimensional image deletion method, deletion should be performed with reference to the pixel position of the display identification map corresponding to the arbitrarily designated pixel position in the composite three-dimensional image formed by the composite three-dimensional image construction method. A surface three-dimensional image is discriminated. Then, using the remaining all surface 3D images excluding the surface 3D image, a new composite 3D image is constructed by the composite 3D image construction method, and a desired surface tertiary in the composite 3D image is formed. Delete the original image.
[0011]
Thus, the desired one or two or more surface three-dimensional images are removed from the constructed composite three-dimensional image, that is, a plurality of surface three-dimensional images that are displayed at the same time, in particular, overlapped, and desired one or two or more The surface 3D image can be displayed as a residual image.
[0012]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 and FIG. 8 are diagrams showing the main part of an embodiment of a 3D image construction method according to the present invention, in which FIG. 1 is a flowchart showing an example of a composite 3D image construction method, and FIG. It is a flowchart which shows an example of the image deletion method.
[0013]
In the method of the present invention, a plurality of CT images are stacked to obtain a stacked three-dimensional image, and a plurality of desired portions in a two-dimensional image viewed from an arbitrary direction are shaded by a depth method. This method is applied to a method of composing a plurality of surface three-dimensional images obtained by converting each depth image using a surface method to construct one composite three-dimensional image.
And in such a method, among the pixel values of the pixels at the same position of the plurality of surface three-dimensional images, the surface three-dimensional image located at the closest distance to the projection surface (viewpoint surface) of the composite three-dimensional image The synthesized three-dimensional image is constructed by selecting and assigning pixel values of pixels of the image as pixel values of pixels constituting the synthesized three-dimensional image. Simultaneously with the composition of the composite 3D image, each pixel position of the composite 3D image and the identification symbol of the surface 3D image in which the pixel value at the pixel position is selected are recorded in the display identification map. (See FIG. 1).
Then, the three-dimensional image to be deleted is determined by referring to the pixel position of the display identification map corresponding to the arbitrarily designated pixel position in the composite three-dimensional image thus configured, and the three-dimensional image Using the remaining all-surface three-dimensional image except for, a new synthesized three-dimensional image is constructed in the same manner as described above to delete a desired three-dimensional image in the synthesized three-dimensional image. (See FIG. 8).
[0014]
In the following, an embodiment of a method for constructing a three-dimensional image according to the present invention will be described separately for the composition of a composite three-dimensional image and the deletion of an arbitrary surface three-dimensional image from the composite three-dimensional image after construction.
[0015]
First, a configuration example of a synthesized three-dimensional image in the method of the present invention will be described sequentially for each step of FIG. 1 using FIGS. In the figure, the CT image is described as a CT image, and the surface three-dimensional image is described as a 3D image or a surface image.
[0016]
Step 11
A desired portion, for example, an organ region (target A) such as a liver is extracted from one CT image CT1. This extraction is performed, for example, by tracing the contour of the object A using the mouse 97 described later. The extraction result is stored in the memory 34 in FIG. 2 as a set of coordinates x and y of the pixel point (pixel position).
[0017]
Step 12
If there are n CT images CT1 to CTn, step 11 is repeated for each CT image CT1 to CTn. Therefore, in step 12, it is determined whether or not the processing in step 11 has been completed for all n CT images.
[0018]
Step 13
An organ region (target B) such as a stomach is extracted from the one CT image CT1. The extraction result is stored in the memory 35 in FIG. 2 as a set of pixel point coordinates x and y.
[0019]
Step 14
If there are n CT images CT1 to CTn, step 13 is repeated for each CT image. For this reason, in step 14, it is determined whether or not the processing in step 13 has been completed for all n CT images.
Finally, N organ regions (objects A, B,... N) are extracted. An exclusion list table (not shown) is used to indicate which of the N objects are used to construct the composite 3D image. This exclusion list table is composed of the identification symbols of the extracted targets A, B,... N and the target usage selection column corresponding to each of the identification symbols, and corresponds to 0 if recorded in the target usage selection column. The target (image) to be used is used, and 1 indicates that it is not used. At this time, it is assumed that 0 (“use”) is recorded in all target use selection fields.
[0020]
Step 15
A surface three-dimensional image of object A is constructed.
3, points p1, p2,... On the CT image 41 are points of the object A. These points are projected onto the viewpoint plane (projection plane) 40 and are designated as P1, P2,. At this time, each point (pixel position) is recorded in a two-dimensional memory (not shown) so that a point having a shorter distance from the viewpoint plane 40 remains at the end. The pixel value recorded for each pixel position is set to a larger value as it is closer to the viewpoint plane 40. In this manner, a depth image 50 (see FIG. 4) shaded according to the distance from the viewpoint plane 40 is obtained in the two-dimensional memory corresponding to the viewpoint plane 40. Further, the depth image 50 is converted into a surface three-dimensional image 51 (see FIG. 4). That is, a gradient (density gradient) created by the density of the depth image 50 is obtained, and the darker the gradient, the brighter the pixel value, the more the surface three-dimensional image 51 is constructed. In FIG. 3, X is the X axis of the projection plane 40, Y is the Y axis, α is the angle formed by the line projected from the origin O to the projection plane 40 on the zx plane and the x axis, and β is The perpendicular is an angle formed with the zx plane. Moreover, the arrow in FIG. 4 shows the direction of each part (surface element) of the depth image 50.
[0021]
Step 16
Similarly to step 15, a surface three-dimensional image of the object B is constructed. Eventually, N (objects A, B,... N) surface three-dimensional images are constructed.
[0022]
Step 17
The surface A, B,... N of the objects A, B,... N are synthesized with reference to the corresponding depth images A, B,. The composed composite three-dimensional image is recorded in the image display memory 93 of FIG.
That is, in FIG. 5, the point a1 of the surface three-dimensional image A (target A), the point b1 of the surface three-dimensional image B (target B),..., The point n1 of the surface three-dimensional image N (target N) is a composite three-dimensional image. In the configuration, the same position (same pixel) is assumed. In this case, which point of pixel values a1, b1,..., N1 should be selected as the pixel value of the corresponding point in the image display memory 93 depends on the depth corresponding to each surface three-dimensional image A, B,. It is determined with reference to the corresponding points ra1, rb1,... Rn1 in the images A, B,. In order to set the pixel value of the point a1, b1,... N1 closest to the viewpoint plane 40 as the pixel value of the corresponding point in the image display memory 93, the depth images A, B,. ... Find the maximum value of N corresponding points ra1, rb1,... Rn1 (see comparison step 66). If the point rbk is the maximum value, the pixel value of the point bk is set as the pixel value of the corresponding point in the image display memory 93 (see selection step 67). For example, if the point rb 1 is the maximum value, the pixel value of the point b 1 is stored in the corresponding point in the image display memory 93. At the same time, an identification symbol (here, image number B) of the surface three-dimensional image in which pixel values are given to the points bk, b1... Is recorded in the display identification map 68 together with the pixel position of the synthesized three-dimensional image 70.
[0023]
The display identification map 68 is as shown in FIG. 6, for example, and an identification symbol indicating which surface three-dimensional image pixel value is given to each point (pixel position) of the combined three-dimensional image 70 is recorded. In FIG. 6, 0 indicates the background, and 1, 2, and 3 indicate the identification symbols of the respective surface three-dimensional images constituting the composite three-dimensional image 70. The above processing is performed for all the points (pixel positions) on the viewpoint plane 40 to form a synthesized three-dimensional image 70.
[0024]
Step 18
The composed composite three-dimensional image 70 is displayed on the monitor 94 (see FIG. 7).
[0025]
Next, an example of deleting a three-dimensional image in the method of the present invention, that is, an example of deleting a part of a surface three-dimensional image (target: organ image) from the synthesized three-dimensional image 70, FIGS. Each step in FIG. 8 will be described sequentially.
[0026]
Step 21
A part of the surface three-dimensional image is deleted from the composite three-dimensional image 70 configured and displayed as described above, or all the surface three-dimensional images are combined and displayed (the above-mentioned composite three-dimensional image is displayed). It is assumed that an icon for selecting whether to configure or display is displayed on the monitor 94 in step 18. In FIG. 7, IC1 indicates a deletion command icon, and IC2 indicates an all-surface 3D image (composite 3D image) display icon. These icons IC1 and IC2 move the cursor 73 that is moved by the operation of the mouse 97 into the display area of the icons IC1 and IC2, and clicks (instructs) the mouse 97 at the position. It is selected and a predetermined step is executed. That is, when the deletion instruction icon IC1 is instructed, the process jumps to step 24, and otherwise jumps to step 22.
[0027]
Step 22
When the mouse 97 is clicked, it is determined whether or not it is an instruction for the all-surface three-dimensional image display icon IC2, and if so, the process jumps to step 23, and otherwise jumps to step 28.
[0028]
Step 23
0 is recorded in all of the target usage selection fields of the exclusion list table, and the above-described step 17 is executed to compose a composite 3D image, and the above-described step 18 is executed to monitor the configured composite 3D image 70. (Refer to FIG. 7).
[0029]
Step 24
As shown in FIG. 7, the cursor 73 is moved to the display area of the surface 3D image to be deleted in the composite 3D image 70 displayed on the monitor 94, and the image to be deleted by clicking the mouse 97 at that position. Instruct.
[0030]
Step 25
Reference is made to the display identification map 68 (see FIG. 5). In the example of FIG. 7, the cursor 73 indicates the image of the identification symbol 2 (see FIG. 6), and therefore the surface three-dimensional image of the identification symbol 2 is deleted in the subsequent steps.
[0031]
Step 26
1 (“not used”) is recorded in the target usage selection column of the exclusion list table corresponding to the identification symbol found in step 25, here the identification symbol 2.
[0032]
Step 27
Except for the surface 3D image in which 1 is recorded in the target use selection field of the exclusion list table, the above-described step 17 is executed to form a combined 3D image, and the above-described step 18 is executed to form the combined 3D image The image 70 is displayed on the monitor 94.
At this time, the display area of the surface three-dimensional image to be deleted, that is, only the identification symbol found in step 25, here, the area where the identification symbol 2 is entered may be reconstructed and displayed. Processing is done.
[0033]
Step 28
It is determined whether or not an end icon (not shown) has been selected and instructed, and if so, the process is ended, and if not, the process jumps to step 21.
Thereafter, Step 21 to Step 28 are repeated.
[0034]
FIG. 9 is a block diagram showing a hardware configuration example to which the method of the present invention can be applied. In FIG. 9, 90 is a CPU, 91 is a main memory, 92 is a magnetic disk, 93 is an image display memory, 95 is a mouse controller, and these are connected to a common bus 96. The magnetic disk 92 stores the plurality of CT images, the exclusion list table, a display identification map, a program for performing the processing shown in FIGS. Reference numeral 94 is a CRT monitor, and 97 is a mouse.
[0035]
In the illustrated configuration, the CPU 90 reads a plurality of CT images and programs from the magnetic disk 92, and performs the processing shown in FIGS. 1 and 8 using the main memory 91, the image display memory 93, and the like. As a result, a composite three-dimensional image 70 as shown in FIG. 7 is displayed on the screen of the CRT monitor 94.
[0036]
The mouse 97 connected to the mouse controller 95 is used for various instructions (including tracing of the contour of the target at the time of target extraction) when the CPU 90 performs the processing shown in FIGS. Used.
The obtained depth image, surface three-dimensional image, composite three-dimensional image, and the like are stored in the magnetic disk 92 as necessary.
[0037]
Although not described directly in the above-described embodiment, as long as each depth image, surface 3D image, exclusion list table, and display identification map exist, the composite 3D image construction method and 3D image deletion method are used. Of course, it is also possible to construct a new composite three-dimensional image by once again joining the deleted surface three-dimensional image.
[0038]
【The invention's effect】
As described above, according to the present invention, not only can a plurality of surface three-dimensional images be combined to form a single combined three-dimensional image, but also the combined three-dimensional image, that is, simultaneously displayed, particularly overlapped. By removing one or more desired surface three-dimensional images from a plurality of displayed surface three-dimensional images, it is possible to display the desired one or more surface three-dimensional images, for example, on an image workstation. It is extremely useful for diagnosis and simulation before surgery.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an example of a synthetic three-dimensional image construction method that is a main part of a method of the present invention.
2 is an explanatory diagram of extraction of a specific organ region (target) from a CT image and storage of the extraction result in a memory in the synthetic three-dimensional image construction method shown in FIG. 1;
3 is an explanatory diagram of perspective transformation for 3D image construction in the composite 3D image construction method shown in FIG. 1. FIG.
FIG. 4 is a diagram illustrating an example of a depth image and a surface three-dimensional image.
FIG. 5 is an explanatory diagram of a composition of a combined three-dimensional image and creation of a display identification map.
FIG. 6 is a diagram illustrating an example of creating a display identification map.
FIG. 7 is a diagram illustrating a monitor display example of a composed composite 3D image.
FIG. 8 is a flowchart showing an example of a three-dimensional image deletion method which is a main part of the method of the present invention.
FIG. 9 is a block diagram showing a hardware configuration example to which the method of the present invention is applied.
[Explanation of symbols]
CT1 to CTn n CT images A, B, ... N Extraction target 40 Viewpoint plane (projection plane)
41 CT image 50 Depth image 51 Surface three-dimensional image 68 Display identification map 70 Composite three-dimensional image 73 Cursor IC1 Deletion command icon IC2 All-surface three-dimensional image (composite three-dimensional image) display icon 90 CPU
91 Main memory 92 Magnetic disk 93 Image display memory 94 CRT monitor 95 Mouse controller 96 Common bus 97 Mouse

Claims (3)

A plurality of CT images of the subject are stacked, a stacked three-dimensional image obtained by combining the plurality of subjects of the subject is obtained, and a two-dimensional image obtained by viewing the stacked three-dimensional image from an arbitrary direction is shaded by a depth method. To obtain a depth image and construct a surface three-dimensional image using the surface method for the depth image;
Displaying the structured Surface 3D image on a monitor;
Selecting an object to be deleted in the displayed Surface 3D image;
Displaying a delete icon displayed on the monitor to delete the selected object to be deleted;
Deleting the object to be deleted from the displayed Surface 3D image by the mouse click;
A method for constructing a three-dimensional image, comprising: Creating a display identification map according to the position information of each target of the displayed Surface 3D image, and further including generating an exclusion list table for excluding from the display target by the generated display identification map;
The method of constructing a 3D image according to claim 1, wherein the deleting step deletes an object existing in the generated exclusion list table from the displayed surface 3D image . Displaying on the monitor an all object display icon for displaying all objects of the Surface 3D image;
Clicking the displayed all target display icon with a mouse;
A step of displaying all objects of the surface 3D image from the display state in which the display object is deleted by the deletion step due to the mouse click;
The method for constructing a three-dimensional image according to claim 1, further comprising :

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