JP2003153894A - Method, device and program for processing three- dimensional image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract a region of interest (ROI) without damage by correctly and efficiently removing an unnecessary region in an image which is obtained by performing volume rendering in voxel data from which an effective region is extracted. SOLUTION: The effective region is extracted from voxel data (S101 and S102), a seed region is set in ROI in the effective region (S103 and S104) and an expansion degree is designated (S105). The seed region is expanded in response to the expansion degree in a connection region in the effective region (S106) and the expanded seed region is removed or extracted from the effective region (S113).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to volume rendering based on voxel data, and particularly to three-dimensional image processing for removing or extracting another region of interest when another region of interest is connected to the region of interest. A method, an apparatus and a program.

[0002]

2. Description of the Related Art CT (Computed Tomography) and MRI (Magnetic Resonance) have made it possible to directly observe the internal structure of the human body by the progress of image processing technology using a computer.
The emergence of sonance imaging is a technology that has brought innovation to the medical field, and medical diagnosis using tomographic images of living bodies is widely performed. Furthermore, in recent years, as a technique for visualizing a three-dimensional structure inside an object that is difficult to understand only with a tomographic image, C
3 from 3D digital data of the object obtained by T etc.
Volume rendering, which directly draws an image of a three-dimensional structure, is widely used.

Ray casting is known as an excellent technique for volume rendering. Ray casting is an image image that sees through a three-dimensional structure inside an object by irradiating an object with a virtual ray (ray) and forming an image of virtual reflected light from the inside of the object on a virtual projection plane. Is a method of forming. Regarding ray casting, for example, “New Generation 3D CT Diagnosis”
(November 1, 1995, published by Nankodo Co., Ltd.), the basic theory is described.

The main points of ray casting will be described. A minute unit area that is a constituent unit of a three-dimensional area of an object is called a voxel, and unique data representing characteristics such as a voxel density value is called a voxel value. The whole object has a voxel value of 3
It is represented by voxel data that is a dimensional array. Usually C
By stacking the two-dimensional tomographic image data obtained by T or the like along the direction perpendicular to the tomographic plane and performing necessary interpolation, three-dimensional array voxel data can be obtained.

It is assumed that the virtual reflected light with respect to the virtual ray emitted from the virtual start point to the object is generated according to the opacity (opacity value) artificially set with respect to the voxel value. Normally, the opacity value takes a value from 0 to 1, and when the value is 0, it is transparent, when it is 1, it is opaque, and the value in between is opaque. Furthermore, to capture the virtual surface, the gradient of voxel data, that is, the normal vector is obtained, and the shading coefficient for shading is calculated from the cosine of the angle formed by the virtual ray and the normal vector. The virtual reflected light is calculated by multiplying the intensity of the virtual light ray applied to the voxel by the opacity of the voxel and the shading coefficient. By accumulating the virtual reflected light along the virtual light ray, an image image through which the three-dimensional structure inside the object is seen is obtained on the virtual projection plane.

When using volume rendering in medical diagnosis, for example, when performing volume rendering on a blood vessel in a human body, first, an effective region including a target vascular tissue is extracted from voxel data. By specifying (threshold specification) the range of voxel values corresponding to the target human body tissue, only voxels having voxel values in a specific range can be validated. When obtaining the opacity value in the extracted voxel, the opacity value of the voxel in the effective area is set to a positive value, and 0 is set outside the effective area. If the opacity value of a voxel is 0, the voxel is interpreted as transparent and is not reflected in the volume rendering.

When performing volume rendering on the voxel data from which the effective area is extracted as described above,
Since the range of the voxel value of each human body tissue is wide, not only the region of interest is necessarily extracted, but other regions may be connected and extracted. As a result, when the human body tissue to be the target of medical diagnosis is viewed, it is difficult to observe because it is obstructed by other regions.

FIG. 12 shows an example of an image obtained by performing volume rendering on voxel data in which an effective area is extracted, and bone is slightly connected to blood vessel tissue. Here, when observing only vascular tissue to make a medical diagnosis, it is desirable to cut only the bone part in this voxel data, but since the bone is connected to the vascular tissue in a three-dimensional shape, The process of cutting only the part of is generally accompanied by difficult work.

Conventionally, there is a method as shown in FIG. 13 as a processing for removing a connected area in such voxel data. FIG. 13 (a) shows a case where human tissues appear to overlap but are not actually connected.
By specifying a point and deleting the connected area including this point, only the bone part is cut and voxel data of the vascular tissue is obtained. On the other hand, FIG. 13B shows a case where the bone is actually connected to the blood vessel tissue. When one point inside the bone to be cut is designated and the connection area including this point is deleted, the bone is connected. All existing vascular tissue is also deleted.

As a countermeasure against this, there is a method of changing the threshold designation shown in FIG. 13 (c). This narrows the range of the voxel value for extracting the effective area so that the human body tissue is separated and extracted, and the target area is cut therefrom.

For example, in FIG. 13 (c), one point inside the bone to be cut is designated as shown in 501 for the human body tissue separated and extracted by changing the threshold designation, and this point is included. 5 when you delete the connected area
As shown in 02, only the bone part is cut. Thereafter, as shown by 503, when the threshold designation is restored, the desired vascular tissue is restored. At this time, the bone part other than the cut region is also restored. It is possible to cut the restored bone part if the connecting part is successfully cut, but if the connecting part remains as a result of the restoration, cutting of only the bone part is not achieved.

As described above, it is difficult to remove an unnecessary area to form a desired area only by changing the threshold designation, and the work is repeated until a desired result is obtained, which is desirable. It is highly possible that this result will not be obtained, and this method is very inefficient.

As another method, there is a method of performing an operation on voxel data using a three-dimensional figure and removing the area of the three-dimensional figure. FIG. 14 shows an example of a method of area removal using such a three-dimensional figure. As the three-dimensional figure, a plane, a curved surface, a sphere, a polygon, or the like is used.

FIG. 15 shows an example of performing area removal on the image of FIG. 12 using a plane. Volume rendering is performed by changing the starting point of ray casting, and after the connected portion is grasped, the calculation is performed by aligning the plane position with the connected portion and cutting the area as shown in 702. Thereafter, as shown at 703, one point inside the bone to be cut is designated, and the connecting region including this point is deleted. As shown at 704, only the bone portion is cut, and the desired vascular tissue is obtained.

However, since the connecting portion is cut by a plane which is interactively aligned, the area of the obtained connecting portion of the vascular tissue may be deformed. In this way, since this method uses existing 3D figures, it does not recognize connected areas,
There is a drawback that the area is cut regardless of the shape of the object.

As another method, there is a method of performing a mask calculation of a region. This is for performing operations such as addition, subtraction, AND operation, expansion, and contraction of the area on the effective area. This method also has a disadvantage that it is difficult to use because it is a mechanical calculation and does not recognize the connected region, and the original shape of the object may be deformed.

By combining the above-mentioned techniques, for example, 3
It is also possible to remove the target region by using a method of changing the threshold designation after dividing the connected region by using the region removal by the three-dimensional figure and the mask calculation of the region. However, there are drawbacks that the procedure is complicated, skill is required, labor and time are required, and the original shape of the object to be left may be deformed during the operation.

FIG. 16 shows an example in which a method of changing the threshold designation and a mask calculation method by dilation are used in combination for the image of FIG. First, as shown in 802, one point inside the bone to be cut is designated for the human body tissue separated and extracted by the change of the threshold designation, and the connected region including this point is deleted, as shown in 803. Only the inner part of the bone is cut. After that, expansion calculation is performed on the obtained blood vessel region to form a mask region as indicated by 804. Finally, a mask operation is performed on the original effective area using the mask area, so that the area outside the mask area is cut as shown by 805 to obtain a desired area.

However, as shown at 805, the formed mask region does not recognize the connecting region, and the mask region is formed by pure expansion, so that the finally obtained region has some bones. There is a high possibility that the portion of will be taken into the mask area and the portion to be cut remains.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in volume rendering based on voxel data in which an effective area is extracted, a human tissue that is not a target of a medical diagnosis is targeted. It is possible to provide a three-dimensional image processing method, device, and program capable of accurately and efficiently deleting an unnecessary region of human body tissue when connected to each other and extracting the region without damaging the region of interest of the human body tissue. To aim.

[0021]

The three-dimensional image processing method according to claim 1 of the present invention performs volume rendering by ray casting on voxel data.
In the three-dimensional image processing method, the effective region of voxel data is extracted (FIG. 1: S101, S102), and the seed region is set in the region of interest in the effective region (FIG. 1: S10).
3, S104), and specify the degree of expansion (Fig. 1: S105),
Deforming the seed region according to the expansion degree in the connection region in the effective region (FIG. 1: S106), and removing or extracting the deformed seed region from the effective region (FIG. 1: S113). It includes.

The three-dimensional image processing program according to the eleventh aspect is a three-dimensional image processing program for performing volume rendering on voxel data by ray casting, in which the computer extracts interest in the effective area extracted from the voxel data. The seed region functioning as a means for removing or extracting from the effective region after the seed region set in the region is deformed in the connection region in the effective region according to a predetermined expansion degree.

According to the inventions of claims 1 and 11,
By setting the seed region in the region of interest and deforming it in the connected region in the effective region according to the specified expansion degree, the shape of the deformed seed region can be easily adjusted to the most suitable one. Therefore, it is possible to accurately and easily obtain a connected region having an appropriate shape to be removed or extracted from the effective region. Moreover, in this method, the shape of the object is not deformed by the operation.

A three-dimensional image processing method according to a second aspect of the present invention is the three-dimensional image processing method according to the first aspect,
The effective area is confirmed by volume rendering (FIG. 1: S107), and the setting of the expansion degree and the seed area is interactively specified (FIG. 1: S108,
S109), and deform the seed region according to the expansion degree in the connection region in the effective region (FIG. 1: S10).
6), the result of removing or extracting the deformed seed region from the effective region is confirmed by volume rendering (FIG. 1: S107), and this is repeated in the same order.

According to the second aspect of the invention, a series of processes including the setting of the expansion degree and the seed area, the deformation of the seed area in the connected area in the effective area, and the confirmation by the volume rendering can be interactively performed. Therefore, the work can be performed while evaluating the shape of the connected region to be removed or extracted from the effective region, and a more accurate result can be easily obtained.

A three-dimensional image processing method according to a third aspect of the present invention is the three-dimensional image processing method according to the second aspect.
The result of removing the deformed seed region from the effective region is confirmed by highlighting the boundary between the effective region and the deformed seed region.

A three-dimensional image processing program according to a twelfth aspect is the three-dimensional image processing program according to the eleventh aspect, wherein a result obtained by removing the deformed seed area from the effective area is defined as the effective area. The boundary with the deformed seed region is emphasized and displayed on the screen.

According to the inventions of claims 3 and 12,
By highlighting the portion updated by the removal from the effective area, it is possible to easily recognize whether all the portions to be removed are removed or whether the portions to be removed are not removed.

A three-dimensional image processing method according to a fourth aspect of the present invention is the three-dimensional image processing method according to the second aspect.
The result of removing or extracting the deformed seed area from the effective area is confirmed by volume rendering of only the update area on the screen.

A three-dimensional image processing program according to a thirteenth aspect is the three-dimensional image processing program according to the eleventh aspect, in which a result obtained by removing or extracting the deformed seed area from the effective area is displayed on a screen. This is to function as means for displaying on the image by volume rendering of only the upper update area.

According to the inventions of claims 4 and 13,
By locally performing the volume rendering process only on the area that needs to be updated on the screen, the calculation load is reduced and the screen can be updated quickly. The entire screen can be updated in real time with high image quality.

A three-dimensional image processing method according to a fifth aspect of the present invention is the three-dimensional image processing method according to the first aspect,
On the image obtained by volume rendering, specify an arbitrary point, line or shape, trace the ray from the viewpoint direction to the depth direction, and connect it to the corresponding point, line or shape on the voxel data that arrived first An area within the projected area is set as a seed area on the target surface (see FIGS. 5 and 6).

A three-dimensional image processing program according to a fourteenth aspect is the three-dimensional image processing program according to the eleventh aspect, in which an arbitrary point, line or shape designated on the image obtained by volume rendering is started. A ray is traced from the viewpoint direction to the depth direction as a position, and it functions as a means for setting the area in the projection area that connects with the corresponding point, line, or shape on the voxel data that arrives first as the seed area on the target surface. It is a thing.

According to the inventions of claims 5 and 14,
By designating a partial area of the object surface, the entire connected surface can be set as the seed area. for that reason,
The object surface of interest can be simply and accurately used as the seed area.

A three-dimensional image processing method according to a sixth aspect of the present invention is the three-dimensional image processing method according to the first aspect,
Specify an arbitrary point, line, or shape on the image obtained by volume rendering, perform ray tracing from the viewpoint direction to the depth direction, and target the corresponding point, line, or shape on the voxel data that arrived first It is set as a seed region on the surface.

A three-dimensional image processing program according to a fifteenth aspect is the three-dimensional image processing program according to the eleventh aspect, in which an arbitrary point, line or shape designated on an image obtained by volume rendering is started. Set the position, trace the ray from the viewpoint direction to the depth direction,
It serves as a means for setting a corresponding point, line, or shape on the voxel data that reaches first as a seed region on the target surface.

According to the inventions of claims 6 and 15,
Since any point, line or shape can be set as the seed area on the surface of the object, it is possible to confirm the result by changing the setting of the seed area variously according to the situation of the human body tissue to be the target of medical diagnosis. It is possible to obtain a more appropriate result easily. In the inventions according to claims 6 and 14, since the area on the voxel data corresponding to an arbitrary two-dimensional figure designated on the image obtained by volume rendering is directly used as the seed area, the shape of the seed area on the object surface Can be specified exactly.

A three-dimensional image processing method according to a seventh aspect of the present invention is the three-dimensional image processing method according to the first aspect.
The seed area is set inside the target. According to a fifteenth aspect of the invention, in the three-dimensional image processing program according to the eleventh aspect, the seed area is set inside the target.

According to the inventions of claims 7 and 16,
The seed area can be set inside the object by using the existing method. For example, an existing algorithm for obtaining the center line of the blood vessel can be used to set the accurate center line of the blood vessel in the seed region.

The three-dimensional image processing method according to claim 8 of the present invention is the three-dimensional image processing method according to claim 1, wherein
An arbitrary point, line or shape is specified on the image obtained by volume rendering, ray tracing is performed from the viewpoint direction to the depth direction, and the depth center of the target is set as a seed region inside the target.

A three-dimensional image processing program according to a seventeenth aspect is the three-dimensional image processing program according to the eleventh aspect, in which an arbitrary point, line or shape designated on an image obtained by volume rendering is started. Set the position, trace the ray from the viewpoint direction to the depth direction,
It serves as a means for setting the depth center of the target as a seed region inside the target.

According to the inventions of claims 8 and 17,
By designating the seed area at the center of the depth of the object, the seed area can be set at an approximate central portion inside the object.

A three-dimensional image processing method according to a ninth aspect of the present invention is the three-dimensional processing method according to any one of the fifth to eighth aspects, in which the seed region is on the voxel data from the viewpoint direction. Is expanded in the depth and depth directions, and an area within the specified depth and depth is reset as a seed area (see FIG. 9).

A three-dimensional image processing program according to a eighteenth aspect is the three-dimensional image processing program according to any one of the fourteenth to seventeenth aspects, wherein the seed area is on the voxel data from a viewpoint direction. Is developed in the depth direction and the depth direction, and functions as a means for resetting a region within the specified depth and depth range as a seed region (see FIG. 9).

According to the inventions of claims 9 and 18,
Since the seed region can be expanded in the depth direction and the depth direction, it is possible to set the seed region having an arbitrary shape according to the shape of the human body tissue to be subjected to medical diagnosis in the depth direction and the depth direction.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing a three-dimensional image processing technique according to an embodiment of the present invention. 2 and 3 show a third embodiment of the present invention.
It is a figure explaining a mode that image processing to voxel data of a human body tissue is advanced according to a three-dimensional image processing technology. The image processing described below can also be provided by a program for causing a computer to process each step.

In FIG. 1, first, while performing volume rendering, a range of voxel values for extracting an effective region is designated so that the human tissue to be targeted for medical diagnosis is appropriately displayed from the voxel data. Volume rendering parameters (opacity value, color, enlargement ratio, angle, etc.) are set (S101).

Next, mask data corresponding to the extracted effective area is generated (S102). After that, a desired region of interest is obtained by cutting the mask region indicated by the mask data. At the time of generating the mask data, a region where the opacity value is not 0 is usually set as the mask region.

According to the method of this embodiment, a seed region as a starting point of processing is set in a connected region to be cut in human tissue, and this is gradually transformed by an interactive method to obtain a connected region to be cut. Is something that
Since it can be considered as if the worm-eating area gradually expands, this method is called worm-eating cut.

In order to do this, the shape of the seed region is determined (S103), and the position where the seed region is arranged is designated (S104). Reference numeral 201 in FIG. 2 shows a state in which the seed area is set in the connected area.

Next, the degree of expansion is designated to control the worm-eating cut (S105). The degree of expansion controls the degree of deformation with the seed region as the starting region in the range from positive (expansion) to negative (contraction). The ratio of deformation (volume) to the seed region, the absolute value in units of voxels, etc. May be specified. In the following description, the expansion ratio for the seed region is used as the expansion degree.

With the above preparation, the seed region is deformed in the connection region in the effective region according to the expansion degree, and the deformed seed region is cut from the effective region (S106). This result is confirmed by volume rendering (S10).
7). The results at different degrees of expansion are shown at 202 and 203 in FIG. In addition, in order to easily confirm the cut portion, the cut edge may be emphasized and displayed on the screen. By obtaining a boundary between the effective area and the deformed seed area, and emphasizing (coloring, blinking, animation, etc.) the boundary and drawing it on the screen, it is possible to confirm at a glance what was cut.

From this result, the expansion degree is designated in S108, the seed area position is evaluated in S109, and the cut area is evaluated in S110. If the conditions are not satisfied, the expansion degree is designated in S105 and the seed area in the S104 seed area is evaluated. Returning to the arrangement and the determination of the shape of the seed region in S103, a series of processing for worm-eating cutting is performed again.

If the condition is satisfied in S110, the mask data is updated according to the cut area (S11
1), it is comprehensively determined whether the human tissue to be medically diagnosed is properly extracted (S112). If the condition is not satisfied here, a series of processes for worm-eaten cutting is repeated from S103.

FIG. 3 shows that in the image example in which bones are slightly connected to the blood vessel tissue of FIG. 4, the connected portion can be accurately captured by the method of the present embodiment. In 301 of FIG. 3, first, a seed region is set on the entire surface on the side opposite to the bone with respect to the connecting portion with the vascular tissue. An image 302 viewed from the side by rotating it is shown.

The seed area set on the entire surface of the bone is set on the image obtained by volume rendering from the viewpoint direction (see FIG. 4). As a method of setting the seed area, (1) an arbitrary point is specified on the image obtained by volume rendering, and ray tracing is performed from the viewpoint direction to the depth direction to connect it with the point on the voxel data that reaches first. The area to be set is set as a seed area (point designation: see FIG. 5). (2) The area of any shape is designated on the image obtained by volume rendering, and ray tracing is performed from the viewpoint direction to the depth direction. A region that is connected to the region on the voxel data that reaches first is set as a seed region (region designation: see FIG. 6), or (3) a region of any shape is designated on the image obtained by volume rendering. , The ray is traced from the viewpoint direction to the depth direction, and the area on the voxel data that reaches first is set as the seed area (enclosure: See 7).

In the method (1), the surface of the object connected to the designated point becomes the seed area. Therefore, the separated object surface or even the same object has a gap in the depth from the viewpoint direction, and the object surface that is not connected does not become the seed region.

The methods (2) and (3) are common in that a region having an arbitrary shape is designated on an image obtained by volume rendering, but the method (2) projects a reference image onto an object. While the seed area is set beyond the object surface portion (see FIG. 8A), the method (3) matches the area on the image obtained by volume rendering with the area on the voxel data. The seed area is prevented from being deformed outside the area designated on the image obtained by the volume rendering (FIG. 8B).
reference). Also in the methods (2) and (3), as in the method (1), the separated object surface or even the same object has a gap in the depth from the viewpoint direction, and the object surface that is not connected does not become a seed region.

In the above (1), (2) and (3), the case where the seed region is set on the surface of the target such as bone has been described, but the seed region may be set inside the target. it can. As a method to set the seed area inside the target, on the image obtained by volume rendering,
After designating an arbitrary point, line, or shape, ray tracing is performed from the viewpoint direction to the depth direction, and the depth center of the target is set as the seed area inside the target. For the depth center of the target, specify an arbitrary point, line, or shape on the image obtained by volume rendering, trace the ray from the viewpoint direction to the depth direction, and then first reach the point on the voxel data etc. Can be specified at an intermediate position with respect to a point that has passed through the object.

According to these methods, even if the region of interest has a complicated shape, it is possible to set an arbitrary seed region according to the shape. An arbitrary shape on the image obtained by volume rendering can be specified by a method of painting a designated area, a method of drawing a closed curve to paint substantially the entire area inside the closed curve, or the like.
In addition, in the above methods (1), (2) and (3), it is assumed that each voxel has depth and depth information from the viewpoint direction, and the seed region on the voxel data from the viewpoint direction. By expanding in the depth and depth directions and resetting the area within the specified depth and depth range as the seed area, it is possible to set the seed area of any shape according to the shape in the depth and depth directions. (Adjustment by depth: see FIG. 9).

Next, in FIG. 3, the seed area set by the method (1), (2) or (3) is gradually deformed by interactive work within the bone connecting area, and the result is obtained while performing volume rendering. Check, 303
The deformation is stopped when the deformed seed region reaches the connecting portion with the vascular tissue as shown in FIG. By cutting this deformed seed region from the effective region, a good image of the desired vascular tissue can be obtained.

As described above, the effective area is cut using the seed area, and the volume rendering processing is performed every time the effective area is updated (reflected on the computer screen) to confirm the cutting state. While you can interactively cut worms. But,
Since the volume rendering processing load is large,
By limiting the range in which the volume rendering process is performed to the update area on the screen, the calculation load can be reduced and the screen can be quickly updated.

FIG. 10 shows how to calculate a portion to be subjected to volume rendering processing, and the processing proceeds in the order of (a) to (c). The corresponding processing flow is also shown in FIG. 11 from step S401 to step S401.
This will be described with reference to 407. First, prior to the worm-eating cut, the mask data before the worm-eating cut is copied to M1 and M2 (S402), and then the worm-eating cut is started. After the worm-eating cut, the mask data M2 is updated (S403).

In FIG. 10B, in order to specify the cut portion on the voxel data after the worm-eating cut, the mask data M1 and M2 are compared and the updated three-dimensional coordinates of each voxel are obtained (S404). Two-dimensional coordinates of each pixel on the corresponding screen are calculated from the obtained three-dimensional coordinates of each voxel to obtain an updated area (S405). Note that the above method calculates the update area on the screen from each updated voxel, but it is also possible to directly obtain the update area on the screen by tracing the ray from all pixels on the screen. In the latter method, when a ray hits an update voxel, the pixel corresponding to that ray becomes the update area.

Next, in FIG. 10C, raycasting is performed from the update area on the screen, volume rendering processing is performed only on the update area (S406), and the volume rendering processing result is reflected on the screen (S407).

Through the above processing, the volume rendering processing is limited to the update area on the screen (see FIG. 10).
(C)), the calculation load can be reduced as compared with the case of performing volume rendering processing on the entire screen (FIG. 10D).

As described above, according to the method of the present embodiment, unnecessary human tissue can be cut while confirming interactively on the screen, and the cut area can be adjusted by designating the degree of expansion and adjusting the shape of the seed area. Since the shape can be adjusted, the connecting portion can be cut accurately and efficiently. Moreover, in the method of the present embodiment, the shape of the object is not deformed by the cutting operation.

In the above description, the case where the unnecessary human body tissue region connected to the human body tissue to be the target of medical diagnosis is cut is taken up, but the human body tissue to be the target of medical diagnosis is set as the region of interest. It is obvious that the method of the present embodiment can be similarly applied to the extraction.

[0069]

As described above, according to the present invention,
In a three-dimensional image processing method of performing volume rendering on voxel data by ray casting, a seed region is set in a region of interest, and a seed region is deformed in a connected region in an effective region according to a designated expansion degree. It is possible to easily control the shape of the deformed seed area, and it is possible to accurately and easily remove or extract the connected area of the target from the effective area without deforming the shape of the object. Have.

Further, according to the present invention, since a series of processes including the setting of the expansion degree and the seed area, the deformation of the seed area in the connected area in the effective area, and the confirmation by the volume rendering can be interactively performed.
This has an advantageous effect that the work can be performed while evaluating the shape of the connected region to be removed or extracted from the effective region, and a more accurate result can be easily obtained.

Further, according to the present invention, since any point, line or shape can be set as the seed region,
Depending on the condition of the human tissue that you want to make a medical diagnosis, you can change the setting of the seed area variously and check the result,
More appropriate results can be easily obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing a three-dimensional image processing technique according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating how image processing is performed on voxel data of human body tissue according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a state in which image processing is performed on voxel data of human body tissue according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a seed region.

FIG. 5 is a diagram showing a method of specifying a seed area (point specification).

FIG. 6 is a diagram showing a method of specifying a seed area (area specification).

FIG. 7 is a diagram showing a method of specifying a seed area (enclosing).

FIG. 8A is a diagram showing a seed region set by region designation, and FIG. 8B is a diagram showing a seed region set by enclosing.

FIG. 9 is a diagram showing a method of specifying a seed region (adjustment by depth).

FIG. 10 is a diagram showing how a processing range of volume rendering processing is calculated.

FIG. 11 is a flowchart showing a process of calculating a processing range of a volume rendering process.

FIG. 12 is an image example obtained by performing volume rendering on voxel data in which an effective area is extracted.

FIG. 13 is an example of a conventional method for removing a connected region in voxel data.

FIG. 14 is an example of a conventional method for removing a connected region using a three-dimensional figure.

FIG. 15 is an example of a conventional method for removing a connected region using a plane.

FIG. 16 is an example of a conventional method in which a method of changing a threshold designation and a mask calculation method are used in combination.

[Explanation of symbols]

201-203, 301-303, 501-503, 7
01-704, 801-805 images

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) A61B 5/055 G06T 15/00 200 G01R 33/32 G01N 24/02 520Y G06T 15/00 200 A61B 5/05 380 F term (Reference) 4C093 AA22 AA26 CA01 CA17 CA18 CA50 DA02 DA10 EE01 FF12 FF13 FF15 FF16 FF28 FF43 FG01 FG05 FG20 4C096 AB36 AB44 AD14 AD15 DC18 DC28 DC36 DC40 DD08 5B080 AA17

Claims (19)

[Claims] 1. A three-dimensional image processing method for performing volume rendering on voxel data by ray casting, extracting an effective region of voxel data, setting a seed region in a region of interest in the effective region, and expanding the degree of expansion. And deforming the seed region according to the degree of expansion in a connection region in the effective region, and removing or extracting the deformed seed region from the effective region. Image processing method. 2. The effective area is confirmed by volume rendering, the expansion degree and the setting of the seed area are interactively specified, and the seed area is deformed in the connection area in the effective area according to the expansion degree.
The process of removing or extracting the deformed seed region from the effective region and confirming the result by volume rendering is repeated in the same order.
The described three-dimensional image processing method. 3. The result of removing the deformed seed region from the effective region is confirmed by highlighting a boundary between the effective region and the deformed seed region. 3D image processing method. 4. The three-dimensional image processing method according to claim 2, wherein the result of removing or extracting the deformed seed area from the effective area is confirmed by volume rendering of only the update area on the screen. . 5. An arbitrary point, line, or shape is designated on an image obtained by volume rendering, ray tracing is performed from the viewpoint direction to the depth direction, and the corresponding point on the voxel data that first arrives, The three-dimensional image processing method according to claim 1, wherein an area within the projection area connected to the line or the shape is set as a seed area on the target surface. 6. An arbitrary point, line, or shape is designated on an image obtained by volume rendering, a ray is traced from the viewpoint direction to the depth direction, and the corresponding point on the voxel data that first arrives, The three-dimensional image processing method according to claim 1, wherein a line or a shape is set as a seed region on the target surface. 7. The three-dimensional image processing method according to claim 1, wherein the seed area is set inside the object. 8. An arbitrary point, line or shape is designated on an image obtained by volume rendering, ray tracing is performed from the viewpoint direction to the depth direction, and the depth center of the target is set as a seed region inside the target. The three-dimensional image processing method according to claim 1, further comprising: 9. The voxel data, wherein the seed region is expanded in the depth direction from the viewpoint direction and the depth direction, and a region within the specified depth and depth range is reset as a seed region. The three-dimensional image processing method according to any one of claims 5 to 8. 10. A three-dimensional image processing device for carrying out the three-dimensional image processing method according to claim 1. 11. A three-dimensional image processing program for performing volume rendering on voxel data by ray casting, wherein a computer sets a seed area in a region of interest in the effective region extracted from the voxel data in the effective region. Within the connected area,
A three-dimensional image processing program, which functions as means for removing or extracting from the effective area after deforming in accordance with a degree of expansion designated in advance. 12. A method of displaying the result of removing the deformed seed area from the effective area as a means for displaying on a screen by emphasizing the boundary between the effective area and the deformed seed area. The three-dimensional image processing program according to claim 11. 13. The method according to claim 11, wherein the result obtained by removing or extracting the deformed seed area from the effective area is caused to function as means for displaying on the screen by volume rendering only the update area on the screen. 3D image processing program. 14. A corresponding point on voxel data which reaches first after performing ray tracing from the viewpoint direction to the depth direction, with an arbitrary point, line or shape designated on the image obtained by volume rendering as a starting position. The three-dimensional image processing program according to claim 11, characterized in that the program functions as a means for setting an area in a projection area connected to a line or a shape as a seed area of a target surface. 15. A ray trace is performed from a viewpoint direction to a depth direction with an arbitrary point, line, or shape designated on an image obtained by volume rendering as a start position, and the ray is traced corresponding to the voxel data which reaches first. 13. The device according to claim 11, which functions as a means for setting a point, a line, or a shape as a seed region on the target surface.
Dimensional image processing program. 16. The three-dimensional image processing program according to claim 11, wherein the seed area is set inside the object. 17. A seed region inside a target is centered on the depth center of a target, with a ray traced from the viewpoint direction to the depth direction, with an arbitrary point, line, or shape designated on the image obtained by volume rendering as the starting position. 2. The function as a means for setting as
The three-dimensional image processing program according to 1. 18. The seed area is expanded on the voxel data in the depth direction and the depth direction from the viewpoint direction, and is made to function as a means for resetting the area within the specified depth and depth range as the seed area. Claim 1 characterized by the above.
The three-dimensional image processing program according to any one of 4 to 17. 19. A three-dimensional image processing apparatus for executing the three-dimensional processing program according to claim 11.