JP2001250133A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device which can specify a depth position more securely when an area of interest including a depth direction is specified in a three-dimensional image displayed on a screen. SOLUTION: This device is equipped with a means which specifies points (A1, A2, etc.), specifying a plane range of the area of interest in the three- dimensional image P displayed on the screen, a means which displays the sectional image T (T1, T2, etc.), passing the specified points on the screen, and a means which specifies points (B1, B2, etc.), specifying a depth range of the area of interest in the displayed sectional image; and the depth range is specified by using the sectional image, so the depth position can be specified more accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT
When a desired region of interest is specified for a three-dimensional image obtained by, for example, a volume rendering method from a tomographic image obtained by an RI device or the like, and a distance, an angle, an area, a volume, or the like there is obtained, the region of interest is The present invention relates to an image display device having a function that allows a depth direction to be specified accurately.

[0002]

2. Description of the Related Art In a medical field, it is necessary to specify a region of interest including a depth direction in a three-dimensional medical image obtained by a volume rendering method or the like and to measure a shape feature amount of a lesion there. Useful. However, a three-dimensional image formed by a volume rendering method or the like is one in which a virtual ray is attenuated over a certain range and shaded based on pixel information in that range to make it three-dimensional. Therefore, even if a point for specifying a region of interest is specified on the three-dimensional image, the position cannot be specified in the depth direction.

[0003] Regarding such a problem, MEDICAL IMAGING
One solution is shown in TECHNOLOGY Vol.17 No.4 July 1999 (18th Annual Meeting of the Japanese Society of Medical Imaging Technology). In this method, the point at which the accumulation of opacity (opacity) is maximized is regarded as a designated point of the depth position (three-dimensional position), so that the depth position can be specified.

[0004]

Although the above-mentioned conventional method is useful as it is, it cannot be specified as one pattern because there can be a plurality of patterns in how to give opacity and how to change a designated point. I have a problem. In other words, the point where the opacity is maximized may not be regarded as the designated point, and in such a case, the error in the depth position may increase.

[0005] Accordingly, an object of the present invention is to provide an image display device capable of more securely specifying a depth position.

[0006]

According to the present invention, a region of interest including a depth direction in a three-dimensional image is specified on a screen on which the three-dimensional image is displayed. In the image display device, for the three-dimensional image displayed on the screen, a unit that specifies a point that specifies a planar range of the region of interest, and a cross-sectional image passing through the point specified by the unit is displayed on the screen. And a means for designating a point for designating a depth range of the region of interest with respect to the cross-sectional image displayed by this means.

According to the present invention, in the above-described image display apparatus, there is provided a means for obtaining a density value of a pixel of a three-dimensional image at a designated point in a depth range designated by the means, and a density value obtained by the means. According to a preferred aspect, there is further provided a means for automatically obtaining a depth range designated point corresponding to a plane range designated point other than one plane range designated point designated by the means.

[0008]

FIG. 1 shows a block diagram of an image display device according to an embodiment of the present invention. The image display device is
CPU1 and CP that perform various processes and overall management described later
A main memory 2 used to store programs and data required for processing by U1, a three-dimensional image to be processed and a tomographic image as a base thereof, and data obtained by processing by CPU1 are stored. Disk 3, a display memory 4 for displaying images, a display device 5 for displaying images output via the display memory 4, a mouse 7 for inputting via a controller 6, and a keyboard 8. Comprising.

The process of designating a region of interest in such an image display device is performed according to the flow shown in FIG. First, a three-dimensional image or a weighted projection image to be processed is read from the magnetic disk 3 and displayed on the display device 5 (step 1). An example is shown in FIG. As shown in FIG. 3, on the screen of the display device 5, “Cancel”, “Distance”,
The input icons of “angle”, “area” and “volume” are displayed. In the next step 2, the designated number n is set to n = 0. In step 3, on the three-dimensional image P displayed on the display device 5, a point (first specified point) A1 for specifying the planar range of the region of interest intended by the operator is specified by the mouse 7 or the like. In step 4, as shown in FIG. 3, a cross-sectional image T1 passing through the plane range designated point A1 is displayed on the display device 5 side by side with the three-dimensional image. A point B1 for specifying the depth range of the area is specified by the mouse 7 or the like. Regarding this, as illustrated in the figure, a projection line (line of sight) L of the three-dimensional image passing through the first designated point A1 is displayed on the tomographic image T1, and the designated range of the point B1 is limited to this straight line L. You may make it.

Here, an example of a method of creating the above-mentioned cross-sectional image will be briefly described. If the three-dimensional image is created by the parallel projection method, it is created as shown in FIG. 5, and if the three-dimensional image is created by the central projection method, FIG.
(A). That is, a cross-sectional image is created as a plane image on a plane including the designated point from a plurality of tomographic images that are the basis of the three-dimensional image. A display screen corresponding to FIG. 3A in the case of the center projection method is as shown in FIG. 6B.

In step 5, 1 is added to the designated number n. In step 6, it is determined whether or not a stop due to “stop” has been input.
Jump to. Otherwise, go to the next step 7. In step 7, it is determined whether or not a distance calculation request has been input based on “distance”, and if the input has been made, the process jumps to step 12. Otherwise, go to the next step 8. In step 8, it is determined whether or not an angle calculation request has been input based on "angle". If the input has been made, the process jumps to step 13. Otherwise, go to the next step 9. Step 9
Then, it is determined whether or not an area calculation request is input based on “area”, and if the input is made, the process jumps to step 14. Otherwise, proceed to the next step 10. In step 10, it is determined whether a volume calculation request has been input based on “volume”. If the input has been made, the process jumps to step 15. Otherwise, jump to step 16.

In step 11, a message as to whether to end or reset is displayed on the display device 5. If the end is selected by the operator, the process ends, and if the reset is selected, the process jumps to step 2. In step 12, it is determined whether n ≧ 2. If so, jump to step 20; if not, jump to step 19. In step 13, n ≧ 3
Is determined. If so, jump to step 20; if not, jump to step 19. Step 1
At 4, it is determined whether n ≧ 3. If so, jump to step 20; if not, jump to step 19. In step 15, it is determined whether n ≧ 4. If so, jump to step 20; if not, jump to step 19.

In step 16, it is determined whether or not the next point for specifying the planar range of the region of interest has been specified. When the next point is designated, the process proceeds to step 17. If not, jump to step 6. In step 17, (b) of FIG.
As shown in the example, a cross-sectional image T2 passing through a newly designated next planar range designated point A2 is displayed, and a designated point B2 of the depth range is designated on this tomographic image T2. At step 18, 1 is added to the designated number n, and then at step 6
Jump to. In step 20, each of distance, area, angle, and volume is calculated according to the instruction from the previous step, and the result is displayed. In these calculations, respective coordinate values are obtained for each plane range designated point and each depth range designated point, and each calculation is performed based on the coordinate values. These calculations are performed based on the concept shown in FIGS. The distance depends on (a), the area depends on (b) and (c), the angle depends on (b), and the volume depends on (d). These areas, angles and volumes are approximations of a triangular surface. In addition, a curve approximation method using spline interpolation can be used for the approximate calculation of the area and the volume. In the calculation of the area or volume, three or more points need to be specified for specifying a planar range as illustrated in FIG. Therefore, it is necessary to repeat the processing up to step 18 a number of times corresponding to the required n before performing these calculations. At the time of such repetition, it is also possible to specify a point that has already been specified again, and correct it as an active point (indicated by a white square in FIG. 4).

In the above-described processing example, a tomographic image passing through the designated plane range designation points is displayed and the depth range designated point is designated each time, but the designated depth range designated point is designated. Simplification is also possible. For that, with respect to the designated point B1 (or another designated point Bi) in the depth range corresponding to the first designated point A1 (or another designated point Ai) in the plane range, the density value of the pixel corresponding to the position is obtained. By using this density value, other depth range specification points are automatically specified. Such processing is possible for the following reasons. If the target three-dimensional image is a medical image of the human head as in the example in the figure, there are skin, skull, discomfort, etc. in the depth direction of the three-dimensional image, which is unique to each of these tissues. Has a density value of Therefore, if the density value of the pixel corresponding to the position of the designated point on the tomographic image is obtained, the depth range of the region of interest intended by the operator can be specified. That is, the density value can be obtained simply by specifying one point for specifying the depth range on the tomographic image, and the depth range intended by the operator can be uniquely determined based on this density value. The specification of the range specification point can be performed only once.

An example of a method of designating a region of interest by another method will be described below. One method is to specify a depth range using an indicator rod. As shown in FIGS. 8 and 9, two indicator rods B1 and B2 that intersect each other are displayed on the screen (projection plane) of the display device. The indicating rods B1 and B2
All of them come out of the points S1 and S2 set at arbitrary positions and intersect in the tomographic image. The CT values (generally, pixel values) of these indicating rods B1, B2 are C, which gives the maximum opacity.
T value. The coordinates of the intersection of the pointing rods B1 and B2 are “far” displayed on the screen of the display device as shown in the example of FIG.
Control with the "near" icon. That is, the intersection on the screen is dragged with the mouse, and the depth direction with respect to the screen is operated by clicking the icons “far” and “near”.

Here, it is assumed that the spherical organ shown in FIG. 8 is a display object having a CT value close to the maximum opacity. As described above, the CT value that gives the maximum opacity is assigned to the CT values of the pointers B1 and B2. Under these conditions,
If the intersection of the pointing rods B1 and B2 is closer to the projection plane than the display target, the one closer to the projection plane is displayed, so that FIG.
Is displayed together with the intersection. If the intersection of the pointing rods B1 and B2 is on the display target surface, the result is as shown in FIG. 9B, and the point beyond the intersection is inside the display target and is not displayed on the screen. Pointers B1, B2
When the intersection of is located deeper than the display target, the indicator rods B1 and B2 are displayed apart from each other as shown in FIG. 9C. Therefore, in order to specify the surface to be displayed, the display state as shown in FIG. 8B may be obtained, and the coordinates of the intersection of the pointing rods B1 and B2 at that time are the surface coordinates of the display object. . That is, the range in the depth direction can be specified by specifying the surface coordinates of the organ to be selected or the like by the intersection of the pointing rods B1 and B2.

Another method is to use opacity. There are several more methods for utilizing opacity, depending on how conditions are established. First, there is a method in which a point (distance from the projection plane = R) where a pixel holding a density value at which opacity is maximized is set as a designated point in the depth direction intended by the operator. Next, the attenuation of the virtual ray = Σα (CT (P
There is a method of setting a point where n)) exceeds 50% as a designated point in the depth direction intended by the operator. That is, FIG.
When the virtual ray advances as shown in FIG. The attenuation in this case depends on the opacity curve as shown in FIG. 10A, the opacity α depends on the CT value, and the CT value depends on the pixel position Pn on the projection line passing through the viewpoint.

Further, the position of the pixel point holding the density value at which the opacity is maximized is defined as R, and (R-r1) to (R-r1)
A method in which the point at which the attenuation of the virtual ray becomes 50% in the range of (R + r2) is set as a designated point in the depth direction, that is, the coordinates of the designated point are set in the range of (R-r1) to (R + r2) on the projection line. There is a way.

The method using the opacity as described above is as follows.
Compared to the conventional method in which the point at which the opacity is maximized is regarded as the designated point, there is an advantage that it is possible to freely designate a desired organ or the like depending on the setting of the numerical value. .

As described above, according to the present invention, when a region of interest including the depth direction is specified for a three-dimensional image, the depth position can be specified more reliably. Can improve the quality of diagnosis and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a flow of processing in an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a screen displayed on a display device in a processing process.

FIG. 4 is a diagram illustrating an example of a screen displayed on a display device in a processing process.

FIG. 5 is an explanatory diagram of how to obtain a cross-sectional image in the parallel projection method.

FIG. 6 is an explanatory diagram of how to obtain a cross-sectional image in the center projection method.

FIG. 7 is an explanatory diagram of a method of obtaining a distance, an area, an angle, and a volume.

FIG. 8 is a diagram showing a relationship among a projection plane, a tomographic image, an axis, and a pointer in the case of the parallel projection method.

FIG. 9 is a diagram showing how the pointing stick appears on the screen.

FIG. 10 is an explanatory diagram of a method of specifying a depth range using an opacity calculation value.

FIG. 11 is an explanatory diagram of attenuation of a virtual ray.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 5 Display device (display means) 7 Mouse (designation means) A Plane range designated point B Depth range designated point P 3D image T Cross-sectional image

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 5/36 510 A61B 5/05 380 F term (Reference) 4C096 AB36 AB44 AD14 DC23 DC24 DC28 DC36 DC37 5B050 AA02 BA03 CA07 EA26 FA02 FA09 5B057 AA07 BA03 BA07 BA24 DA08 DA16 DC03 DC04 DC08 5C082 AA04 AA22 AA24 AA37 BA12 BA46 CA02 CA03 CA54 CB05 DA86 MM05

Claims (1)

[Claims] 1. On a screen on which a three-dimensional image is displayed,
In an image display device configured to be able to specify a region of interest including a depth direction in the three-dimensional image, a point that specifies a planar range of the region of interest with respect to the three-dimensional image displayed on the screen. Means for specifying, a means for displaying a cross-sectional image passing through the point specified by this means on the screen, and means for specifying a point for specifying the depth range of the region of interest with respect to the cross-sectional image displayed by this means. An image display device comprising: