JP2000298732A - Three-dimensional image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily display a three-dimensional image as both a translucent image and a completely opaque image. SOLUTION: Threshold for translucent display and threshold for complete opaque display are set, and a projector 22 from an observing point to a projection plane 21 is designated. Whether points (a), b, c, d, and e on the projector 22 satisfy the condition of the translucent display and the condition of the completely opaque display is decided. As a result, since the points c and d fulfill the condition of the translucent display, the translucence display is operate, and since the point e fulfills the condition of the complete opaque display, the complete opaque display is made. This process is operated on all projectors so that the completely opaque display of blood vessels 25 is realized, while the translucent display of liver 24 can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional image display device, and more particularly to a three-dimensional image display device that displays a liver blood vessel and the like in a completely opaque manner while displaying the entire liver and the like translucently.

[0002]

2. Description of the Related Art In order to clarify the relationship between the whole and a part of a three-dimensional image, there is a case where, for example, the whole liver is displayed translucently, and the blood vessels of the liver are desired to be displayed completely opaque.
In the conventional three-dimensional image display device, the whole liver and the blood vessels of the liver are separately extracted and synthesized.

[0003]

However, the conventional three-dimensional image display apparatus has a drawback that it takes much time to extract the whole liver and the blood vessels of the liver separately.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a three-dimensional image display device that can easily display translucent and completely opaque.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention projects a three-dimensional original image including a subject on a projection surface and performs shading to display the three-dimensional image. In the display device, a first condition for extracting a pixel to be translucently displayed from the three-dimensional original image;
Condition setting means for setting a second condition for extracting a pixel to be completely opaquely displayed, and performing a process for translucent display on the pixel extracted by the first condition in the three-dimensional original image. Image reconstructing means for performing a process for completely opaque display on the pixels extracted under the second condition to reconstruct an image in which a completely opaque image is synthesized into a translucent image. Features.

According to the present invention, the condition setting means includes a first condition for extracting a pixel for translucent display from a three-dimensional original image and a second condition for extracting a pixel for completely opaque display.
And conditions are set. The image reconstructing means performs a process for translucent display on the pixels extracted under the first condition in the three-dimensional original image, and performs a process for completely opaque display on the pixels extracted under the second condition. To reconstruct an image in which a completely opaque image is combined with a translucent image. In this manner, it is determined whether each point in the three-dimensional original image satisfies the condition for translucent display and the condition for completely opaque display, and based on the determination result, each point is processed for semi-transparent display or completely opaque display. By reconstructing the synthesized image, it is possible to easily display the image as translucent and completely opaque.

Further, the coordinates of the pixel extracted according to the second condition can be recorded on a recording medium, and the distance, area and volume can be calculated from the recorded coordinates. Further, a first point is selected on the reconstructed first image, a second point is selected on a second image different from the first image, and the first point and the second point are selected. Can be calculated.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a three-dimensional image display device according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing the principle of the three-dimensional image display device of the present invention. A three-dimensional original image in which a plurality of tomographic images 23 including a liver 24 and a blood vessel 25 of the liver 24 are stacked is centrally projected on a projection plane 21 with a viewpoint (not shown) as a center, and a projected image projected on the projection plane 21 The three-dimensional image is reconstructed by shading. While the liver 24 is displayed translucently, the blood vessel 25 is reconstructed by the surface method and displayed completely opaque.

First, a threshold for translucent display and a threshold for completely opaque display are set, and a projection line 22 from the viewpoint to the projection plane 21 is designated. A point a that first intersects the tomographic image 23 on the projection line 22 is set as a calculation point (a point at which shading is calculated) and whether the condition of the translucent display and the condition of the completely opaque display are satisfied for the point a Is determined. As a result, since the point a does not satisfy the condition of the translucent display or the condition of the completely opaque display, the calculation point is set to the point b by moving a certain distance from the viewpoint. It is determined whether or not the condition of the translucent display and the condition of the completely opaque display are satisfied for the point b. Since neither the condition of the translucent display nor the condition of the completely opaque display is satisfied for the point b as in the case of the point a,
The calculation point is set at a point c away from the viewpoint by a certain distance.

It is determined whether or not the condition of the translucent display and the condition of the completely opaque display are satisfied for the point c. As a result, the point c satisfies the condition of the translucent display. The inner product is obtained, and the translucency of the point c is obtained from the inner product value. The calculation point is set to the point d, and it is determined whether the condition of the translucent display and the condition of the completely opaque display are satisfied for the point d. Since the point d also satisfies the condition of the translucent display similarly to the point c, Find the inner product of the concentration gradient vector and the line-of-sight vector,
The translucency of the point d is obtained from the inner product value.

An operation point is set at a point e. Since the point e satisfies the condition of complete opaque display, an inner product of a density gradient vector and a line-of-sight vector is obtained, and a luminance 1 of the point e is obtained from the inner product value. The luminance of the point e is obtained from the luminance 1 and the translucency of the points c and d, and the coordinates of the point e are stored. Thus, the points c and d on the liver 24 can be displayed translucently, and the point e on the blood vessel 25 can be displayed completely opaque. By performing this for all projection lines, the blood vessel 25 can be displayed completely opaque while the liver 24 is displayed translucent.

FIG. 2 is a flowchart showing an image display procedure of the three-dimensional image display device of the present invention. First, threshold values t1 and t2 for translucent display and threshold values s1 and s2 for completely opaque display are set (step S).
1). This setting is performed by inputting with a mouse 32 or a keyboard, or by reading from a magnetic disk.

The first projection line 22 is designated (Step S)
2). Normally, the line going to the upper left of the projection plane 21 is the first projection line 22, and the translucency sum = 0. Set the start point of the calculation point on the specified first projection line (step S
3). Usually, the start point is the point where the projection line first intersects the tomographic image (point a in FIG. 1). It is determined whether the set calculation point satisfies the conditions of the threshold values s1 and s2 for the completely opaque display (step S4).

As a result of the determination, if the condition is not satisfied, it is determined whether or not the calculation point satisfies the conditions of the threshold values t1 and t2 (step S5). If the condition is not satisfied as a result of the judgment, the position of the calculation point is set to a fixed distance (on the projection line) (fine increment)
Only from the viewpoint (step S8). For example, FIG.
Moves from point a to point b. The distance from the viewpoint at this time is R.

If the condition is satisfied in step S5, an inner product of the density gradient vector and the line-of-sight vector at the calculation point is obtained (step S6). The density gradient vector is a unit vector perpendicular to the iso-CT value plane of a series of multiple CT images, and the line-of-sight vector is parallel to the projection line in the case of parallel projection, and the center of all projection lines in the case of central projection. Is parallel to the straight line.

From the inner product value obtained in step S6, sum is obtained using equation 1 (step S7). sum = sum + coefficient × inner product value Expression 1 The position of the calculation point is moved away from the viewpoint by a certain distance (on a projection line) (a slight increment) (step S8). For example, in FIG.
Move from point to point b. The distance from the viewpoint at this time is R
And It is determined whether R> Rmax (step S
9). Rmax is a preset maximum value. As a result of the determination, if R> Rmax is not satisfied, the process returns to step S4 to repeat the processing.

If the condition is satisfied in step S4, the inner product of the density gradient vector and the line-of-sight vector is obtained for shading as a surface image, and the luminance 1 is obtained from the inner product by equation (2). Brightness 1 = coefficient × square product × (Rmax−R) (2) Here, the coefficient is input by a keyboard.

Further, the luminance is corrected by the equation 3 using the translucency (sum) of the organ located on the viewpoint side from the calculation point, and the result is displayed (step S12). Luminance = luminance 1− (constant−sum) × coefficient Expression 3 Luminance 1 is, for example, an operation value at point e in FIG.
This is the calculated value at point c. The coefficient is input using a keyboard or the like, and indicates the presence of the translucent portion.

The coordinates of the calculation point (point e in FIG. 2) are stored (step S13). It is determined whether all the projection lines have been designated (step S10). As a result of the determination, if all the projection lines have been designated, the process ends. If all the projection lines have not been specified, the next projection line is specified (step S11).
Sum is set to 0, the process returns to step S3, and the process is repeated.

Further, since the coordinates of the calculation points are stored in step S13, the distance, area and volume can be calculated from the stored coordinates. As shown in FIG. 3, by touching two points P1 and P2 on the blood vessel 25 of the three-dimensional image displayed on the CRT monitor 31 with the mouse 32 and clicking the mouse, the liver 24 displayed translucently is displayed. Blood vessels 25 displayed completely opaque but not
The above measurement is possible.

Further, a point P3 is selected on the three-dimensional image displayed on the CRT monitor 31 in FIG.
By selecting the point P4 on the rotated three-dimensional image displayed on the CRT monitor 31, the distance between the two points P3 and P4 can be measured.

FIG. 5 is a block diagram showing a hardware configuration of the three-dimensional image display device of the present invention. The three-dimensional image display device records and displays medical image data collected on a target site of a subject by a medical image diagnostic device such as an X-ray CT device or an MRI device, and controls the operation of each component. A central processing unit (CPU) 40, a main memory 42 storing a control program of the device, a magnetic disk 44 storing a plurality of tomographic images and image reconstruction programs, and the like, and displaying reconstructed image data. Memory 46, a CRT monitor 31 as a display device for displaying image data from the display memory 46, a mouse 32 as a position input device, and a CRT monitor 31 for detecting the state of the mouse 32. A mouse controller 48 that outputs signals such as the position of the mouse pointer above and the state of the mouse 32 to the CPU 40 is connected to the above components. Constructed from a common bus 52 that.

[0022]

As described above, according to the present invention, the condition setting means determines whether each point in the three-dimensional original image satisfies the condition for translucent display and the condition for completely opaque display, and performs image reconstruction. The means performs the processing for translucent display or complete opaque display of each point based on the determination result and reconstructs the synthesized image, so that the points can be easily displayed in translucent and completely opaque.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the principle of a three-dimensional image display device according to the present invention.

FIG. 2 is a flowchart showing an image display procedure of the three-dimensional image display device of the present invention.

FIG. 3 is an explanatory diagram showing a calculation method of a distance, an area, and a volume.

FIG. 4 is an explanatory diagram showing a method of calculating a distance between two points on two different images.

FIG. 5 is a block diagram showing a hardware configuration of the three-dimensional image display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Projection surface 22 ... Projection line 23 ... Tomographic image 24 ... Liver 25 ... Blood vessel 31 ... CRT monitor 32 ... Mouse 40 ... CPU 42 ... Main memory 44 ... Magnetic disk 46 ... Display memory 48 ... Mouse controller

Claims (1)

[Claims] 1. A three-dimensional image display device for projecting a three-dimensional original image including a subject on a projection surface and displaying a three-dimensional image by performing shading on the three-dimensional original image. Condition setting means for setting a first condition for extracting a pixel and a second condition for extracting a pixel to be completely opaquely displayed; and a condition set by the first condition in the three-dimensional original image. The pixel extracted by the second condition is subjected to a process for translucent display, and the pixel extracted according to the second condition is subjected to a process for completely opaque display to reconstruct an image in which a completely opaque image is combined with the translucent image. A three-dimensional image display device comprising: