JP2006305203A - Ct image display method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the localized understanding as well as the total understanding of a position and a direction of a three-dimensional region of interest. <P>SOLUTION: In a CT image display, sectional images of an X sectional plane, a Y sectional plane and a Z sectional plane of an XYZ coordinate system which pass a point of interest in the three-dimensional region and perpendicularly intersect each other and a volume rendering image are displayed to be mutually related on a screen of a display apparatus on the basis of the reconstitution data of the three-dimensional region. Here, the reconstitution data of the three-dimensional region is generated by reconstituting the projection data, the X sectional image, the Y sectional image and the Z sectional image are generated on the basis of the reconstitution data, and the volume rendering image is generated around the point of interest of a subject on the basis of the reconstitution data. Then, the X sectional image, the Y sectional image, the Z sectional image and the volume rendering image are displayed on the screen of the display apparatus together with an X cursor, a Y cursor and a Z cursor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to display of CT images.

  In X-ray CT imaging, X-ray projection data is collected, and the data is reconstructed based on the data to obtain a cross-sectional image. The three-dimensional data of the subject is expressed as, for example, voxel data, and the surface shape is displayed based on the voxel data.

As a method for displaying the reconstruction data, there is a slice section method (MPR). In order to display the reconstructed data intuitively and easily, for example, in the three-dimensional display described in Japanese Patent Laid-Open No. 2002-11000, one X tomographic image, Y tomographic image, and Z tomographic image passing through an arbitrary point are displayed. In the screen, they are displayed in association with each other as in a normal front view, plan view, and side view. Since tomographic images viewed from the front, top, and side are displayed, the images are intuitively easy to understand. Here, when an X cursor, Y cursor, or Z cursor is displayed on the screen and any one of the cursors is moved, a tomographic image corresponding to the movement position in the axial direction corresponding to the cursor is selected and displayed. In addition, an image viewed in an arbitrary direction can be created and displayed. For example, an image is displayed corresponding to the movement of the cursor. Note that the X tomographic image, the Y tomographic image, and the Z tomographic image are created and stored in advance for a plurality of tomographic planes.
JP 2002-11000 A

  In CT image display by the conventional slice section method, the slice section is fixed in three directions of axial, coronal, and sagittal. This method is a good method for displaying and grasping imaging data of a large area that can be said to be almost the whole body. However, it is not always a good method to observe the local area. This is because the direction specific to the region of interest is more important than the direction of the body axis. Therefore, it is desirable to be able to understand the overall position and direction of the three-dimensional region of interest and at the same time be able to understand locally.

An object of the present invention is to enable local understanding as well as understanding the overall position and direction of a three-dimensional region of interest.

  According to the CT image display method of the present invention, an X tomographic plane of an XYZ coordinate system passing through points of interest in the three-dimensional region and orthogonal to each other based on reconstruction data of the three-dimensional region obtained by CT imaging, In this image display method, a tomographic image and a volume rendering image of a Y tomographic plane and a Z tomographic plane are displayed on the screen of a display device in association with each other. Here, the projection data collected from the subject is reconstructed to generate reconstruction data of the three-dimensional region of the subject, and is an image of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane passing through the point of interest in the subject. An X tomographic image, a Y tomographic image, and a Z tomographic image are generated based on the reconstruction data, and a volume rendering image is generated based on the reconstruction data with a point of interest of the subject as a center. An X cursor that is a projection line of the X tomographic image, the Y tomographic image, the Z tomographic image, and the volume rendering image onto the other tomographic planes of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane, The image is displayed on the screen of the display device together with the Y cursor and the Z cursor.

  In the CT image display method, preferably, when the position of the point of interest is designated by the operator in the volume rendering image, an image of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane passing through the designated point of interest. An X tomographic image, a Y tomographic image, and a Z tomographic image are generated based on the reconstruction data, and a volume rendering image is generated centering on the indicated interest point. Then, the X tomographic image, the Y tomographic image, the Z tomographic image, and the volume rendering image are displayed on the screen together with the X cursor, the Y cursor, and the Z cursor.

  In the CT image display method, preferably, when the X cursor, the Y cursor, and / or the Z cursor are moved by the operator on the screen, the X tomographic image, the Y tomographic image corresponding to the moved cursor, A Z-tomographic image and a volume rendering image centered on the interest point corresponding to the moved cursor position are generated and displayed on the screen.

  In the CT image display method, preferably, when rotation of an image centered on a point of interest is instructed by an operator in the volume rendering image, a volume rendering image is generated corresponding to the instructed rotation, Also, an X ′ tomographic image, a Y ′ tomographic image of the X ′ tomographic plane, a Y ′ tomographic plane and / or a Z ′ tomographic plane set corresponding to the transformation to the X′Y′Z ′ coordinate system by the rotation, a Y ′ tomographic image, and / Or Z ′ tomographic image is generated. Next, the generated volume rendering image, the X ′ tomographic image, the Y ′ tomographic image, and the Z ′ tomographic image are converted into the other tomograms of the X ′ tomographic plane, the Y ′ tomographic plane, and the Z ′ tomographic plane, respectively. It is displayed on the screen together with the X ′ cursor, Y ′ cursor, and Z ′ cursor that are projection lines onto the surface.

  In the CT image display method, preferably, when rotation of the image is instructed by an operator in any of the X tomographic image, the Y tomographic image, and the Z tomographic image, the other two tomographic images are displayed at the designated angle. A volume rendering image that is generated by rotating only by the specified angle and then rotated by the indicated angle, and then X is set corresponding to the conversion to the X′Y′Z ′ coordinate system by the rotation Displayed on the screen together with the X ′ cursor, Y ′ cursor, and Z ′ cursor, which are projection lines of the “fault plane, Y ′ fault plane, and Z ′ fault plane on the other fault planes.

  In the CT image display method, preferably, in the generation of the volume rendering image, a volume rendering image including an image of a cut surface cut at any of the three tomographic planes is generated.

  In the CT image display method, preferably, when any of the X cursor, Y cursor, and Z cursor is moved, the X tomographic image, the Y tomographic image, the Z tomographic image, and the volume correspond to the movement.・ Create and display a rendered image.

  In the CT image display method, preferably, tomographic images of a plurality of tomographic planes parallel to the X tomographic plane, the Y tomographic plane, and the Z tomographic plane are cut out in advance and stored in a storage device. Then, when displaying the X tomographic image, the Y tomographic image, and the Z tomographic image at an arbitrary point in the three-dimensional region, the corresponding tomographic image is read from the storage means and displayed on the screen.

  In the CT image display method, the volume / rendered image is preferably enlarged or reduced by an operation independent of the movement of the X cursor, Y cursor, and Z cursor.

A CT image display device according to the present invention is based on reconstruction data of a three-dimensional region obtained by CT imaging, and an X tomographic plane of an XYZ coordinate system that passes through points of interest in the three-dimensional region and is orthogonal to each other. An image display device that displays a tomographic image and a volume rendering image of a Y tomographic plane and a Z tomographic plane on a screen of a display device in relation to each other, and reconstructs projection data collected from the subject to reconstruct the subject Reconstruction data generating means for generating reconstruction data of a three-dimensional region, and an X tomographic image, a Y tomographic image, and a Z tomographic image, which are images of an X tomographic plane, a Y tomographic plane, and a Z tomographic plane passing through the point of interest of the subject A tomographic image generating means for generating based on the reconstructed data, and a volume rendered image generating for generating a volume rendered image based on the reconstructed data around a point of interest of a subject. An X cursor that is a projection line of the X tomographic image, the Y tomographic image, the Z tomographic image, and the volume rendering image onto the other tomographic planes of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane, respectively. Display means for displaying on the screen of the display device together with the Y cursor and the Z cursor.

  In the CT image display device, preferably, an instruction means for an operator to instruct a position of a point of interest in the volume rendering image is provided on the screen. The tomographic image generating means converts the X tomographic image, the Y tomographic image, and the Z tomographic image, which are images of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane that pass through the point of interest instructed by the instructing means, into the reconstructed data. The volume-rendered image generating means generates a volume-rendered image centered on the indicated interest point. The display means displays the X tomographic image, the Y tomographic image, the Z tomographic image, and the volume rendering image on the screen together with the X cursor, the Y cursor, and the Z cursor.

In the CT image display device, preferably, an instruction means for an operator to move the X cursor, Y cursor and / or Z cursor on the screen is provided,
The tomographic image generating unit and the volume / rendered image generating unit correspond to the X tomographic image, the Y tomographic image, the Z tomographic image, and the position of the moved cursor corresponding to the cursor moved by the instruction unit. Generate a volume rendering image centered on the point of interest,
The display means displays the created X tomographic image, Y tomographic image, Z tomographic image, and volume / rendered image on the screen together with the X cursor, Y cursor, and Z cursor. A CT image display method for a tomographic image according to 9 or 10.

In the CT image display device, preferably, an instruction unit is provided for an operator to instruct rotation of an image centered on a point of interest in the volume rendering image,
The volume rendering image generation means generates a volume rendering image corresponding to the rotation instructed by the instruction means,
The tomographic image generating means includes an X ′ tomographic image of an X ′ tomographic plane, a Y ′ tomographic plane and / or a Z ′ tomographic plane set in correspondence with the transformation into the X′Y′Z ′ coordinate system by the rotation, Generating a Y ′ tomographic image and / or a Z ′ tomographic image;
The display means displays the generated X ′ tomographic image, Y ′ tomographic image, Z ′ tomographic image, and the volume rendering image in addition to the X ′ tomographic plane, the Y ′ tomographic plane, and the Z ′ tomographic plane. The CT image display device according to claim 9, wherein the CT image display device displays the X ′ cursor, the Y ′ cursor, and the Z ′ cursor, which are projection lines onto the tomographic plane, on the screen.

  In the CT image display device, preferably, an instruction unit is provided for an operator to instruct image rotation in any of the X tomographic image, the Y tomographic image, and the Z tomographic image. The tomographic image generation means generates the other two tomographic images by rotating the designated angle, and the volume rendering image generating means generates a volume rendering image rotated by the designated angle. . The display means sets the generated X tomographic image, Y tomographic image, Z tomographic image, and volume / rendered image corresponding to the conversion to the X′Y′Z ′ coordinate system by the rotation. Displayed on the screen together with the X ′ cursor, Y ′ cursor, and Z ′ cursor, which are projection lines of the “fault plane, Y ′ fault plane, and Z ′ fault plane on the other fault planes.

  In the CT image display device, it is preferable that the volume rendering image generation unit generates a volume rendering image including an image of a cross section cut at one of the three tomographic planes in the generation of the volume rendering image. Generate and display.

  In the CT image display device, preferably, when any of the X cursor, Y cursor, and Z cursor is moved, the tomographic image generation means and the volume rendering image generation means correspond to the movement. The X tomographic image, the Y tomographic image, the Z tomographic image, and the volume rendering image are created and displayed.

  Preferably, the CT image display device further includes a storage device for storing tomographic images of a plurality of tomographic planes at predetermined intervals parallel to the X tomographic plane, the Y tomographic plane, and the Z tomographic plane in advance. When displaying the X tomographic image, the Y tomographic image, and the Z tomographic image at an arbitrary point in the three-dimensional region, the corresponding tomographic image is read from the storage means and displayed on the screen.

Preferably, the CT image display device includes an instruction means for an operator to move the X cursor, Y cursor, and / or Z cursor on the screen, and the tomographic image generation means and the volume rendering image generation means include Generating a volume rendering image centered on a point of interest corresponding to the moved cursor position, and the X tomographic image, the Y tomographic image, the Z tomographic image corresponding to the cursor moved by the instruction means, The volume / rendered image is enlarged or reduced by an operation of the magnification changing means independent of the movement of the X cursor, Y cursor, and Z cursor.

By displaying the three-dimensional view and the volume rendering image in real time, the operator can easily and quickly recognize and observe the volume of interest. The operator can understand the position and direction of the entire three-dimensional region of interest, and the region of interest is appropriately displayed, making it easier to understand the region of interest.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a configuration of an example of a computer 10 that is an example of a CT image display device that displays a tomographic image obtained by CT imaging. The computer 10 includes a central processing unit 12 that controls the whole, a ROM 14 that stores programs, a RAM 16 that is used as a work area, a keyboard that accepts user input, an input device 18 such as a mouse, and various data displayed on the screen. Display device 20 and a hard disk device 22 as an auxiliary storage device.

  The hard disk device 22, which is an auxiliary storage device, stores various programs such as an OS and data (not shown), as well as a three-dimensional area obtained by reconstruction of projection data 30 and projection image data collected from the subject. Reconstruction data (volume data) 32, slice image data 34 which is a tomographic image created from the reconstruction data, and an image reconstruction program 36 (reconstruction data generating means) for reconstructing an image from projection data, three-dimensional display The display program 38 (tomographic image generating means, volume / rendered image generating means) for realizing the above is stored. There are slice section method and volume rendering method for displaying the reconstruction data, and it is desirable to take advantage of both. Therefore, the display program 38 displays three slice images and a volume / rendered image on the screen of the display device 20, as will be described later.

By the image reconstruction calculation by the image reconstruction program 36, reconstruction data is obtained for each point (voxel) constituting the three-dimensional area in the three-dimensional area of the subject. When an XYZ orthogonal coordinate system orthogonal to each other is set for the three-dimensional region, the voxel value V (x, y, z) of a certain point P (x, y, z) is determined in the XYZ coordinate system. In other words, the X fault plane, the Y fault plane, and the Z fault plane pass through an arbitrary point P in the three-dimensional region.
This arbitrary point P is set as a point of interest described later.

  As shown in FIG. 2, the screen 50 of the display device 20 includes an X, Y, Z tomographic image obtained in this manner and includes an arbitrary point P (for example, the center of the three-dimensional region) in the three-dimensional region. The tomographic image 52X, the Y tomographic image 52Y, and the Z tomographic image 52Z are taken out and displayed simultaneously. Here, the three tomographic images are arranged in the upper left, lower left and lower right as in a normal front view, plan view, and side view. For this reason, since a cross-section passing through one arbitrary point is displayed in comparison with three tomographic images viewed from the front, top, and side, the relative relationship between these tomographic images becomes intuitively easy to understand. . In addition, the X tomographic image 52X, the Y tomographic image 52Y, and the Z tomographic image 52Z also display an X cursor 54X, a Y cursor 54Y, and a Z cursor 54Z (instruction means) that are projection lines of the other two tomographic planes. To do. That is, the Y cursor 54Y and the Z cursor 54Z are displayed on the X tomographic image 52X, the Z cursor 54Z and the X cursor 54X are displayed on the Y tomographic image 52Y, and the X cursor 54X and the Y cursor 54Y are displayed on the Z tomographic image 52Z. That is, the Y cursor 54Y displayed in the X tomographic image 52X indicates the position of the Y tomographic plane that crosses the X tomographic plane, and the Z cursor 54Z indicates the position of the Z tomographic plane and is displayed in the Y tomographic image 52Y. The Z cursor 54Z indicates the position of the Z tomographic plane, the X cursor 54X indicates the position of the X tomographic plane, the X cursor 54X displayed on the Z tomographic image 52Z indicates the position of the X tomographic plane, and the Y cursor 54Y indicates the Y tomographic plane. The position of the surface is shown. Accordingly, the relative relationship between the three X tomographic images 52X, the Y tomographic image 52Y, and the Z tomographic image 52Z is easily understood intuitively. The intersection of each cross-section is the point of interest, that is, the center of the region of interest of the subject.

  Further, a volume rendering image 56 is displayed on the upper right. The volume rendering image 56 is drawn with the center of the region of interest at that time as the center of the screen. Assuming that the upper left of the three views is an axial diagram, the lower left is a coronal diagram, and the lower right is a sagittal diagram, the viewing direction of the volume rendering diagram is parallel to the cross-sectional normal vector of the coronal diagram. By simultaneously displaying the three cross-sectional images 52X, 52Y, and 52Z and the volume rendering image 56 on one screen, the operator understands the position and direction of the entire three-dimensional region of interest, and at the same time, is specific to the region of interest. A slice cross-section can be obtained in the direction. In the volume / rendered image 56, the position of the point of interest is indicated by the operator using the X cursor 54X, the Y cursor 54Y, and the Z cursor 54Z. In other words, the slice cursor can be positioned on the region of interest and linked to the volume / rendered image 56 in real time. FIG. 3 shows an example of the screen display.

  Now, when the rotation of the region of interest is instructed with the mouse (instruction means) in the volume rendering screen, and when the mouse is dragged in the three-view image, X ′ from the XYZ coordinate system by the rotation is correspondingly changed. An X ′ tomographic image, a Y ′ tomographic image, a Y ′ tomographic image and / or a Z ′ tomographic image of the X ′ tomographic plane, the Y ′ tomographic plane and / or the Z ′ tomographic plane set in correspondence with the conversion to the Y′Z ′ coordinate system; A volume rendering image 56 is created and displayed. Here, the X ′ tomographic plane, the Y ′ tomographic plane, and the Z ′ tomographic plane are displayed on the screen together with the X ′ cursor, the Y ′ cursor, and the Z ′ cursor that are projection lines to the other tomographic planes. When the image is rotated, the “center of the region of interest” always follows the original three-dimensional position. In addition, the X cursor 54X, Y cursor 54Y, and Z cursor 54Z that are simultaneously displayed on the three plane views 52X, 52Y, and 52Z are moved in parallel on the screen, or the cursor is moved as the cursor is rotated. Three corresponding tomographic images 52X, 52Y and 52Z and a volume rendering image 56 are created and displayed. In this way, the display and operation of the volume-rendered three-dimensional image and the three cross-sectional views are linked to facilitate the operator's understanding of the three-dimensional object.

In the present application, three-dimensional coordinates are indicated by using alphabets of X, Y, and Z. However, when a new conversion is performed by rotating an image from this coordinate, the converted coordinates are expressed as X only when the conversion is performed. It is indicated using the alphabets', Y ', Z', and after the conversion is completed, the three-dimensional coordinates are indicated using the alphabets X, Y, Z as before.

FIG. 11 is an example in which the Z coordinate of the region of interest in FIG. 3 is changed by moving the Z cursor 54Z. With the change of the Z coordinate, the Z tomographic image 52Z displays a new slice image. Since the volume rendering image 56 is drawn with the center of the region of interest at that time as the center of the screen, it moves so that the center of the new region of interest becomes the center of the screen as the Z coordinate is changed. As described above, when the X cursor 54X, the Y cursor 54Y, and the Z cursor 54Z are moved on the screen by the operator, the X tomographic image, the Y tomographic image, the Z tomographic image corresponding to the moved cursor, and A volume rendering image centered on the point of interest corresponding to the moved cursor position is generated and displayed on the screen.
That is, when any of the X cursor, Y cursor, and Z cursor is moved, the X tomographic image, Y tomographic image, Z tomographic image, and volume / rendered image are newly created in accordance with the movement. Is displayed.

  FIG. 4 shows a situation when the axial diagram of FIG. 3 is rotated, or when the volume rendering image 56 is rotated in the horizontal direction. The center of the region of interest shows the same points as in FIG. Here, the directions of the cross sections of the coronal diagram and the sagittal diagram are changed. The Z slice cursor is moved and the Z section (upper left) is changed accordingly. For example, when the Z cross section is rotated, the Y cross section (lower left) and the X cross section (lower right) are converted accordingly, and the volume rendering image also changes direction accordingly. Thus, not only the position of the region of interest but also the direction can be set arbitrarily.

  The image display program 38 similarly performs three tomographic images and volume rendering on the X′Y′Z ′ coordinate system rotated by a desired angle with respect to the original XYZ coordinate system by performing a rotation process of the coordinate axes. Images can be created and displayed. Note that when an image rotation instruction is continuously given for a long time, three-volume and volume-rendered images are created and displayed at an appropriate rotation interval even during the instruction. The interval may be set arbitrarily.

したがって、単位ベクトルｎと角度θを元に回転後の位置が計算できる。画像の各点についてこの計算を行うことにより回転された画像が得られる。 The calculation of the image rotation will now be described. As shown in FIG. 5, a three-dimensional space vector a ₀ representing the position of one point in the image is set in the direction of the right-hand thread with the unit vector n in the three-dimensional space as an axis. , The vector a ₁ obtained by the rotation is expressed as follows.

Therefore, the position after rotation can be calculated based on the unit vector n and the angle θ. By performing this calculation for each point of the image, a rotated image is obtained.

When rotating the volume rendering image 56 and the tomographic image, it is necessary to consider the following five vectors in order to represent the relative relationship between the volume and the observer.
(1) Viewpoint position vector p _e
(2) the position vector _{p c} of the center of the region of interest
(3) the viewing direction of the unit vector _{Y = (p c -p e)} / | p c -p e |
(4) “Upward” unit vector Z on the screen (perpendicular to vector Y)
(5) “Right” unit vector X = Y × Z on the screen
Volume rendering and slicing are performed based on these five vectors. However, it parametrizes that can be set independently only _p c, _{p e} and Z.

There are two methods for rotating the volume rendering image in the counterclockwise direction by θ.
(1) The volume is rotated by θ around the depth vector of the screen.
(2) The screen frame is rotated by -θ around the screen depth vector.
Here, the latter method is adopted, and the coordinate axis for representing the vector component is fixed to the volume rendering image 56.

ここで、Ｒ（n,θ）は、回転軸方向の単位ベクトルnの周りの角θ回転させる演算子である。この場合、視点の位置ベクトルｐ_ｅと関心領域の中心の位置ベクトルｐ_ｃは動いていないので、再描画は（ｐ_ｅ，ｐ_ｃ,Ｚ’）を元に行う。 FIG. 6 shows an example of display when the volume is rotated around an axis perpendicular to the screen on the volume rendering screen. In this case, the “upward” unit vector Z and the “right” unit vector X of the screen may be rotated by θ around the unit vector Y in the line-of-sight direction.

Here, R (n, θ) is an operator that rotates the angle θ around the unit vector n in the rotation axis direction. In this case, the position vector p _c of the center of the position vector p _e and ROI point of view not moving, redraw performed based on the _{(p e, p c, Z} ').

このとき、関心領域の中心を回転中心としたため、ｐ_ｃは不動であり（ｐ_ｃ＝ｐ'_ｃ）、視点と関心領域の中心との距離は不変である（｜ｐ_ｃ’−ｐ_ｅ’｜＝｜ｐ_ｃ−ｐ_ｅ｜）。したがって視点を

によって与えられるｐ'_eに動かさなくてはならない。このようにして求めたベクトルを元に再描画を行う。 FIG. 7 shows an example in which the volume rendering image 56 is rotated and displayed around an axis parallel to the screen on the volume rendering screen. The user instructs rotation by dragging the mouse on the volume rendering screen. The dragged distance corresponds to the angle θ, and the direction perpendicular to the drag direction is the vector n. Therefore, the image is rotated by -θ around the vector n in the screen plane.

At this time, due to a rotation around the center of the region of interest, p _c is immobile _{(p c = p 'c)} , the distance between the center of the visual point and the region of interest is unchanged (| p _c' -p _e ' _{| = | p c -p e |} ). Therefore, the perspective

Must be moved to p ' _e given by. Redrawing is performed based on the vector thus obtained.

  A slice cross-sectional image (tomographic image) can be created as follows. A straight line passing through the center of the volume and parallel to the vectors X, Y, and Z will be referred to as an X axis, a Y axis, and a Z axis. A slice cross-sectional image is created in a plane perpendicular to these axes. For example, as an X slice section, a plane parallel to a plane including the Y axis and the Z axis (X plane) is taken, and a slice image is created so that the X axis comes to the center of the screen. Thereby, when the distance from the X plane of the X slice section is changed, a consistent display can be obtained. A Y slice sectional image and a Z slice sectional image can be similarly created. The slice thickness is set appropriately. Note that the calculation of the rotation of the slice cross-sectional image is performed when the rotation axis n is any one of the vectors X, Y, and Z in the calculation of the rotation of the volume rendering image described above. Only.

FIG. 8 is a flowchart of image display when an operator instructs rotation of a slice on the screen. When the rotation around the upward unit vector Z is instructed (YES in S10), the forward unit vector Y and the right unit vector X are rotated (S12). (There is a relationship of X = Y × Z.) When rotation around the rightward unit vector X is instructed (YES in S16), the forward unit vector Y and the Z axis are rotated (S18). In either case, then, it calculates the viewpoint position vector p _e from forward unit vector Y and ROI center position vector p _c (S14). Further, when rotation around the forward unit vector Y is instructed (S20), the upward unit vector Z and the right unit vector X are rotated (S22). Next, an image is generated based on these vector values. First, a slice diagram is drawn based on the region-of-interest center position vector _pc , the forward unit vector Y, the right-point unit vector X, and the upward unit vector Z (S24). Next, the viewpoint position vector p _e , the region-of-interest center position vector p _c, forward unit vectors Y, draws a volume rendering (voir) image based on the right unit vector X and the upward unit vector Z (S26).

FIG. 9 is a flowchart of the assembling operation instructed by the operator to rotate the volume / rendered image on the screen. The rotation axis unit vector n and the rotation angle θ are obtained from the operator's instruction (S40). Viewpoint Next, forward unit vector Y, rightward unit vector X, the upward unit vector Z and the rotation angle θ about the axis of rotation unit vector n (S42), also from forward unit vectors Y and ROI center position vector p _c The vector _pe is calculated (S44). Then, a slice diagram is drawn based on the region-of-interest center position vector _pc , the forward unit vector Y, the right-point unit vector X, and the upward unit vector Z (S46), and the viewpoint position vector p _e , the region-of-interest center position vector P Then, a volume rendering image is drawn based on the forward unit vector Y, the right unit vector X, and the upward unit vector Z (S48).

The volume rendering image may be displayed so as to include an image of a cut surface cut along one of the three tomographic planes X, Y, Z or X ′, Y ′, Z ′. FIG. 10 shows an example of such a volume rendering image. Here, for example, a volume rendering image cut at the cutting plane 58 including the point of interest is displayed. In addition, if the position (coordinates) and direction of the cut surface on the screen are fixed, the image moves within the screen while the position of the cut surface is fixed when the operator instructs the movement of the viewpoint. To go.

Note that the X tomographic image, the Y tomographic image, and the Z tomographic image are cut out and stored as slice image data at predetermined intervals from the reconstruction data of the three-dimensional region in advance, and displayed on the screen of the display device 20 as required. May be. In this case, the image display program 38 cuts out a three-dimensional region at a predetermined interval and creates a tomographic image in advance. Here, to cut out an X tomographic image on a plane perpendicular to the X axis, that is, an X tomographic plane, x coordinates (x = x0, x1,..., Xn) at predetermined intervals are determined and have the x coordinates. The voxel values V (x, y, z) on the X tomographic plane may be arranged on a two-dimensional plane. The X tomographic image thus obtained at the coordinate xm is described as X (y, z) _xm . By this method, images of the X tomographic plane perpendicular to the X axis, that is, X (y, z) _x0 , X (y, z) _x1 ,..., X (y, z) _xn are cut out in advance. Similarly, images Y (z, x) _y0 , Y (z, x) _y1 ,..., Y (z, x) _yn perpendicular to the Y axis are cut out at a predetermined interval, Vertical Z tomographic images Z (x, y) _z0 , Z (x, y) _z1 ,..., Z (x, y) _zn are cut out at predetermined intervals. In one example, 41 X tomographic planes, 41 Y tomographic planes, and 31 Z tomographic planes are created. When the cursor is moved, an image of the tomographic plane corresponding to the position is read and displayed.

The volume / rendered image 56 may be enlarged or reduced by an operation independent of movement of the X cursor, Y cursor, and Z cursor.
For example, the X cursor 54X, Y cursor 54Y, and Z cursor 54Z are moved by dragging and dropping the mouse, and the volume / rendered image 56 is enlarged or reduced with a general-purpose roller while pressing the shift key of the computer. You may make it carry out by operation of the roller (magnification change means) of a mouse | mouth. With this configuration, the effect of viewing the volume / rendered image 56 from a viewpoint distant from a bird's eye view and the effect of viewing the volume / rendered image 56 from a viewpoint close to the target site are produced.

  Further, the volume rendering image 56 may be displayed translucently so that the entire structure of the region of interest can be visually recognized. For this purpose, for example, image reconstruction may be performed roughly so that the volume / rendered image data at the back of the display screen can be seen from the gap between the data of the volume / rendered image in front of the display screen. The volume / rendered image data at the back of the display screen may be seen through the volume / rendered image data in front of the display screen by lowering the opacity of the entire data, that is, increasing the transparency. In this case, if the points of interest on the cursor are displayed so as to be particularly conspicuous, it is easier to visually recognize the points of interest in the region of interest.

  The image display is applied to, for example, a CT image of a dental arch, but is not limited thereto, and it is needless to say that the image display can also be applied to display of an otolaryngological CT image, a spinal CT image, or the like.

Block diagram of a computer which is an image display device Illustration of CT image display on the screen Illustration of one example of screen display FIG. 3 is a diagram showing an example of a screen after the rotation is instructed from the display of FIG. Diagram for explaining rotation calculation The figure which shows the situation where the volume is rotated around the axis perpendicular to the screen on the volume rendering screen The figure which shows the situation where the volume is rotated around the axis parallel to the screen on the volume rendering screen Flow chart of image display when rotation of slice is instructed by the operator on the screen A flowchart of the assembling instructed to rotate the volume rendering image by the operator on the screen Illustration of a volume rendering image including a cut surface Illustration of one example of screen display

Explanation of symbols

    10 Computer, 12 Central processing unit, 20 Display device, 22 Hard disk device, 30 Projection data, 32 Three-dimensional area reconstruction data (volume data), 34 Slice image data, 36 Image reconstruction program 36, 38 Display program

Claims (18)

Based on the reconstruction data of the three-dimensional region obtained by CT imaging, the tomographic images of the X, Y, and Z tomographic planes of the XYZ coordinate system that pass through the points of interest in the three-dimensional region and are orthogonal to each other And an image display method for displaying volume-rendered images on the screen of a display device in association with each other,
Reconstruct the projection data collected from the subject to generate reconstruction data for the three-dimensional area of the subject,
Generating an X tomographic image, an Y tomographic image, a Y tomographic image, and a Z tomographic image, which are images of an X tomographic plane, a Y tomographic plane, and a Z tomographic plane passing through a point of interest in the subject, based on the reconstruction data;
A volume rendering image is generated based on the reconstructed data around the interest point of the subject,
X cursor, Y cursor, which are projection lines of the X tomographic image, Y tomographic image, Z tomographic image, and volume rendering image onto the other tomographic planes of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane, respectively. And CT image display method for displaying on the screen of the display device together with the Z cursor. When the operator indicates the position of the point of interest in the volume rendering image,
Generating an X tomographic image, a Y tomographic image, and a Z tomographic image, which are images of an X tomographic plane, a Y tomographic plane, and a Z tomographic plane that pass through the designated point of interest, based on the reconstruction data;
Generate a volume rendering image around the indicated interest point,
The CT image display method according to claim 1, wherein the X tomographic image, the Y tomographic image, the Z tomographic image, and the volume rendering image are displayed on a screen together with the X cursor, the Y cursor, and the Z cursor. .   When the X cursor, Y cursor, and / or Z cursor are moved by the operator on the screen, the X tomographic image, Y tomographic image, Z tomographic image, and moved cursor corresponding to the moved cursor 3. A tomographic CT image display method according to claim 1 or 2, wherein a volume rendering image centered on a point of interest corresponding to the position of the tomographic image is generated and displayed on a screen. When rotation of the image centered on the point of interest is instructed by the operator in the volume rendering image, a volume rendering image is generated corresponding to the instructed rotation,
X ′ tomographic images, W ′ tomographic images, W ′ tomographic images and / or X ′ tomographic planes, W ′ tomographic planes and / or Z ′ tomographic planes set corresponding to the transformation to the X′W′Z ′ coordinate system by the rotation. Generate a Z 'tomographic image,
The generated volume rendering image, the X ′ tomographic image, the W ′ tomographic image, and the Z ′ tomographic image are transferred to the other tomographic planes of the X ′ tomographic plane, the Y ′ tomographic plane, and the Z ′ tomographic plane, respectively. The CT image display method according to claim 1, wherein the CT image is displayed on a screen together with an X ′ cursor, a Y ′ cursor, and a Z ′ cursor which are projection lines. When rotation of the image is instructed by the operator in any of the X tomographic image, the Y tomographic image, and the Z tomographic image, the other two tomographic images are generated by being rotated by the designated angle, and Generate a volume rendering image that is rotated by the specified angle,
X ′, which is a projection line of each of the X ′ tomographic plane, the Y ′ tomographic plane, and the Z ′ tomographic plane set in correspondence with the conversion to the X′Y′Z ′ coordinate system by the rotation. 5. The CT image display method according to claim 1, wherein the CT image is displayed on a screen together with a cursor, a Y ′ cursor, and a Z ′ cursor.   6. The volume rendering image according to claim 1, wherein, in the generation of the volume rendering image, a volume rendering image including an image of a cut surface cut by one of the three tomographic planes is generated. CT image display method.   When any of the X cursor, Y cursor, and Z cursor is moved, the X tomographic image, the Y tomographic image, the Z tomographic image, and the volume rendering image are created and displayed in response to the movement. The CT image display method according to any one of claims 1 to 6.   The tomographic images of a plurality of tomographic planes parallel to the X tomographic plane, the Y tomographic plane, and the Z tomographic plane are previously cut out at a predetermined interval and stored in a storage device, and the arbitrary point in the three-dimensional region is stored. 8. The CT according to claim 1, wherein, when displaying an X tomographic image, a Y tomographic image, and a Z tomographic image, the corresponding tomographic image is read from the storage unit and displayed on a screen. Image display method. 9. The CT image display according to claim 1, wherein the volume rendering image is enlarged or reduced by an operation independent of movement of the X cursor, Y cursor, and Z cursor. Method Based on the reconstruction data of the three-dimensional region obtained by CT imaging, the tomographic images of the X, Y, and Z tomographic planes of the XYZ coordinate system that pass through the points of interest in the three-dimensional region and are orthogonal to each other And an image display device for displaying the volume rendering image on the screen of the display device in relation to each other,
Reconstructed data generating means for reconstructing projection data collected from a subject to generate reconstructed data of a three-dimensional region of the subject;
A tomographic image generating means for generating an X tomographic image, a Y tomographic image, and a Z tomographic image, which are images of an X tomographic plane, a Y tomographic plane, and a Z tomographic plane passing through a point of interest of a subject, based on the reconstruction data;
Volume / rendered image generating means for generating a volume / rendered image based on the reconstructed data around the interest point of the subject;
X cursor, Y cursor, which are projection lines of the X tomographic image, Y tomographic image, Z tomographic image, and volume rendering image onto the other tomographic planes of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane, respectively. And a display means for displaying on the screen of the display device together with the Z cursor. Provided on the screen is an instruction means for an operator to indicate the position of a point of interest in the volume rendering image,
The tomographic image generating means converts the X tomographic image, the Y tomographic image, and the Z tomographic image, which are images of the X tomographic plane, the Y tomographic plane, and the Z tomographic plane that pass through the point of interest instructed by the instructing means, into the reconstructed data. Based on
The volume-rendered image generating means generates a volume-rendered image centered on the indicated interest point,
The said display means displays the said X tomographic image, a Y tomographic image, a Z tomographic image, and the said volume rendering image on a screen with the said X cursor, a Y cursor, and a Z cursor. CT image display device. Providing an instruction means for an operator to move the X cursor, Y cursor and / or Z cursor on the screen;
The tomographic image generating unit and the volume / rendered image generating unit correspond to the X tomographic image, the Y tomographic image, the Z tomographic image, and the position of the moved cursor corresponding to the cursor moved by the instruction unit. Generate a volume rendering image centered on the point of interest,
The display means displays the created X tomographic image, Y tomographic image, Z tomographic image, and volume / rendered image on the screen together with the X cursor, Y cursor, and Z cursor. A CT image display method for a tomographic image according to 9 or 10. Providing an instruction means for an operator to instruct rotation of an image centered on a point of interest in the volume rendering image;
The volume rendering image generation means generates a volume rendering image corresponding to the rotation instructed by the instruction means,
The tomographic image generating means includes an X ′ tomographic image of an X ′ tomographic plane, a Y ′ tomographic plane and / or a Z ′ tomographic plane set in correspondence with the transformation into the X′Y′Z ′ coordinate system by the rotation, Generating a Y ′ tomographic image and / or a Z ′ tomographic image;
The display means displays the generated X ′ tomographic image, Y ′ tomographic image, Z ′ tomographic image, and the volume rendering image in addition to the X ′ tomographic plane, the Y ′ tomographic plane, and the Z ′ tomographic plane. The CT image display device according to claim 9, wherein the CT image display device displays the X ′ cursor, the Y ′ cursor, and the Z ′ cursor, which are projection lines onto the tomographic plane, on the screen. Providing an instruction means for an operator to instruct rotation of the image in any of the X tomographic image, the Y tomographic image, and the Z tomographic image;
The tomographic image generating means generates the other two tomographic images by rotating them by an instructed angle,
The volume rendering image generating means generates a volume rendering image rotated by an instructed angle,
The display means sets the generated X tomographic image, Y tomographic image, Z tomographic image, and volume / rendered image corresponding to the conversion to the X′Y′Z ′ coordinate system by the rotation. The display is on the screen together with an X ′ cursor, a Y ′ cursor, and a Z ′ cursor, which are projection lines of each of the “fault plane, Y ′ fault plane, and Z ′ fault plane to the other fault planes. The CT image display apparatus in any one of 9-11.   The volume-rendered image generation unit generates and displays a volume-rendered image including a cross-sectional image cut at one of the three tomographic planes in the generation of the volume-rendered image. Item 14. The CT image display device according to any one of Items 9 to 13.   When one of the X cursor, Y cursor, and Z cursor is moved, the tomographic image generation means and the volume rendering image generation means correspond to the movement, and the X tomographic image, Y tomographic image, and Z The CT image display device according to claim 9, wherein a tomographic image and the volume rendering image are created and displayed.   And a storage device for storing tomographic images of a plurality of tomographic planes at predetermined intervals parallel to the X tomographic plane, the Y tomographic plane, and the Z tomographic plane in advance, and the X for any point in the three-dimensional region. 16. The CT image according to claim 9, wherein when displaying a tomographic image, a Y tomographic image, and a Z tomographic image, the corresponding tomographic image is read from the storage means and displayed on the screen. Display device. Providing an instruction means for an operator to move the X cursor, Y cursor and / or Z cursor on the screen;
The tomographic image generating unit and the volume / rendered image generating unit correspond to the X tomographic image, the Y tomographic image, the Z tomographic image, and the position of the moved cursor corresponding to the cursor moved by the instruction unit. Generate a volume rendering image centered on the point of interest,
The magnification change means for performing enlargement display or reduction display of the volume / rendered image by an operation independent of the movement of the X cursor, Y cursor, and Z cursor. CT image display method described

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