JPH1043178A - Method, device for setting reconstitutive faces, reconstitutive image preparing method and x-ray ct device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time for operation by easily and exactly setting reconstitutive faces. SOLUTION: A pseudo three-dimensional image combining a scout image G0 at 0 deg. and a scout image G90 at 90 deg. is displayed and while utilizing that image, an operator sets reconstitutive faces RP. Then, not the pixel data of all picture elements on an axial plane APi are calculated but only the pixel data of a group of picture elements vx on the reconstitutive faces RP are calculated and these pixel data are synthesized so that a reconstitutive image can be prepared. Thus, the reconstitutive faces can be intuitively set and useless time for operation can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reconstruction plane setting method, a reconstruction plane setting apparatus, a reconstruction image creation method, and an X-ray CT (Computed Tomography) apparatus. More specifically, a reconstruction plane setting method and a reconstruction plane setting device that can easily and accurately set a reconstruction plane, a reconstruction image creation method that can eliminate useless calculations, and a method thereof are preferably used. The present invention relates to an X-ray CT apparatus that can be implemented.

[0002]

2. Description of the Related Art FIG. 11 is a flowchart showing a procedure until a reconstructed image is displayed in a conventional X-ray CT apparatus. In step J1, a so-called helical scan (he
lical scan) to collect scan data. That is, the scan data is collected while moving the subject linearly in the body axis direction with respect to the X-ray detector and rotating the X-ray tube around the subject. In step J2, a reconstruction operation is performed based on the scan data to generate a number of tomographic images perpendicular to the body axis, that is, axial images, at a plurality of positions in the body axis direction of the subject. FIG. 12 conceptually illustrates a number of axial images AG1 to AGI. FIG. 13 illustrates one axial image AGi.

Returning to FIG. 11, in step J3, the operator sets a reconstruction plane using an axial image. That is, as shown in FIG. 14, one axial image AGi, an image HS of a horizontal section passing through the center point of the axial image AGi, and an image of a vertical section passing through the center point of the axial image AGi are displayed on the screen of the display device. VS is displayed, and the intersection line L of each image AGi, HS, VS and the reconstruction plane is displayed.
The positions and angles of L1, L2, and L3 are designated to set the reconstruction plane.

Returning to FIG. 11, in step J4, pixel data of pixels included in the reconstruction plane is collected from pixel data of each axial image. In step J5, the collected pixel data is combined to create a reconstructed image and displayed on the screen of the display device.

[0005]

In a conventional X-ray CT apparatus, as shown in FIG. 14, an axial image AGi, a horizontal section image HS, and a vertical section image VS are displayed, and each of the images AGi, HS, Intersection lines L1, L2 between VS and the reconstruction plane
The reconstruction plane is set by designating the position and angle of L3. However, in such a method, the positional relationship between the subject and the reconstructed surface cannot be intuitively grasped.
There is a problem that it is difficult to set a reconstruction plane at a desired position.

In a conventional X-ray CT apparatus, as shown in FIG. 12, I axial images AG1 to AGI are generated, and the number of pixels of one axial image is 512 ×
Assuming 512, it is necessary to calculate 512 × 512 × I pixel data. However, the number of pixels of the reconstructed image is also 51
If it is set to 2 × 512, 512 × 512 × (I−1) pixel data is not used, and there is a problem that a lot of unnecessary calculations are performed.

Accordingly, a first object of the present invention is to provide a method for setting a reconstructed plane which can easily and accurately set a reconstructed plane. A second object of the present invention is to provide a reconstructed image creating method capable of eliminating useless calculations. Further, a third object of the present invention is to provide an X-ray CT apparatus capable of suitably executing the above-described reconstructed surface setting method and reconstructed image creating method.

[0008]

According to a first aspect, the present invention provides a method for scanning a subject, collecting scan data, creating and displaying a three-dimensional image based on the scan data, and displaying the three-dimensional image. And a method of setting a reconstructed surface by an operator using the display of the reconstructed surface. In the reconstruction plane setting method according to the first aspect, a three-dimensional image is displayed on the screen of the display device, and the operator uses the display of the three-dimensional image to set the reconstruction plane. Since the positional relationship between the sample and the reconstructed surface can be intuitively grasped, even an unskilled operator can easily and accurately set the reconstructed surface.

According to a second aspect of the present invention, in the reconstruction plane setting method having the above configuration, two scout images having different projection plane angles are combined and projected onto a plane intersecting both scout images. A reconstructed surface setting method is provided in which a perspective image as described above is created and displayed as the three-dimensional image. When a three-dimensional model is created to display a three-dimensional image, a relatively long operation time is required for calculating a large number of voxel data. However, in the reconstruction plane setting method according to the second aspect, a pseudo three-dimensional image in which two Scout images having different angles of the projection plane are combined is displayed, so that calculation of a large number of voxel data is unnecessary. And a relatively short operation time is required.

According to a third aspect, the present invention provides a method for setting a reconstructed surface having the above-described structure, wherein a three-dimensional model having a small number of voxels is created, and an image obtained by projecting the three-dimensional model onto one surface is generated. The present invention provides a method for setting a reconstructed surface, which is created and displayed. When a three-dimensional model is created to display a three-dimensional image, a relatively long operation time is required for calculating a large number of voxel data. However, in the reconstruction plane setting method according to the third aspect, since a three-dimensional model in which the number of voxels is reduced is created, a relatively short calculation time is required.

According to a fourth aspect, the present invention provides a method for setting a reconstructed surface having the above-described structure, wherein an image as if a surface model was created and projected on one surface was created as the three-dimensional image. There is provided a method for setting a reconstructed surface characterized by displaying. When a three-dimensional model is created to display a three-dimensional image, a relatively long operation time is required for calculating a large number of voxel data. However, in the reconstructed surface setting method according to the fourth aspect, since the surface model is created, it is sufficient to calculate the voxel data of only the surface, and the calculation time is relatively short.

According to a fifth aspect, the present invention provides a three-dimensional image creating and displaying means for creating and displaying a three-dimensional image based on scan data collected by scanning a subject, and utilizing the display of the three-dimensional image. And a reconstruction plane setting means for allowing an operator to set a reconstruction plane. In the reconstruction plane setting device according to the fifth aspect, a three-dimensional image is created and displayed by the three-dimensional image creation and display means, and the operator reconstructs the three-dimensional image using the display of the three-dimensional image by the reconstruction plane setting means. Since the constituent surfaces are set, the positional relationship between the subject and the reconstructed surface can be intuitively grasped, and even an unskilled operator can easily and accurately set the reconstructed surface. become.

[0013] In a sixth aspect, the present invention provides a method for rotating an X-ray tube around a subject and transmitting the subject while moving the subject relatively to the X-ray tube in the direction of the rotation axis. The X-rays detected by the X-ray detector are collected in scan data, an operator sets a reconstruction plane, and is included in the axial image in a calculation for reconstructing an axial image based on the scan data. A method for generating a reconstructed image, comprising: obtaining only data of pixels on the set reconstructed surface; and combining the obtained data of pixels of each group to create an image of the reconstructed surface. . In the reconstructed image creating method according to the sixth aspect, in the operation for reconstructing the axial image, the pixel data of all the pixels on the axial plane is not calculated, but is included in the axial plane and the Only pixel data is calculated.
Therefore, useless calculations can be eliminated. Note that it is not possible to set a reconstructed surface using a large number of axial images. Therefore, it is preferable to use the reconstructed surface setting method according to the first to fourth aspects.

In a seventh aspect, the present invention provides a method for rotating an X-ray tube around a subject and transmitting the subject while moving the subject relatively to the X-ray tube in the direction of the rotation axis. Data collection means for detecting the obtained X-rays with an X-ray detector and collecting scan data, three-dimensional image creation display means for creating and displaying a three-dimensional image based on the scan data, and display of the three-dimensional image A reconstruction plane setting means for allowing an operator to set a reconstruction plane by using the scan plane, and an arithmetic operation for reconstructing the axial plane based on the scan data, which is included in the axial plane and on the set reconstruction plane. A reconstructing operation means for obtaining only the pixel data of the group, and an image forming means for forming the image of the reconstructed surface by combining the obtained pixel data of each group.
A T device is provided. In the X-ray CT apparatus according to the seventh aspect, a three-dimensional image is displayed on the screen of the display device, and the operator uses the display of the three-dimensional image to set a reconstruction plane. The positional relationship between the surfaces can be intuitively grasped, and even an unskilled operator can easily and accurately set the reconstructed surface. Furthermore, in an operation for reconstructing an axial image, pixel data of all pixels of the axial image is not calculated, but only data of pixels included in the axial image and on a reconstruction plane are calculated. Calculation can be eliminated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited by this.

FIG. 1 is a configuration diagram showing an X-ray CT apparatus according to one embodiment of the present invention. This X-ray CT apparatus 100
Has an operation console 1, an imaging table 10, and a scanning gantry 20. The operation console 1
Is an input device 2 for receiving operator's instructions, information, etc.
And a central processing unit 3 for executing scan processing, image reconstruction processing, reconstruction plane setting processing, reconstruction image creation processing, and the like.
And a control signal and the like to the imaging table 10 and the scanning gantry
Control interface 4 for outputting to 0 and scanning gantry 2
Data collection buffer 5 for collecting data acquired at 0
And a CRT 6 for displaying images and the like, and a storage device 7 for storing various data and programs. The imaging table 10 moves the subject on the body axis direction. The scanning gantry 20 includes an X-ray tube 21, a collimator 22, a detector 23, a rotation controller 24 that rotates the X-ray tube 21 and the detector 23 around a body axis of a subject, An X-ray controller 25 for adjusting the timing and intensity of X-ray irradiation by the X-ray tube 21; a collimator controller 26 for adjusting the degree of opening of the collimator 22; and a data collection unit 27 for collecting data obtained by the detector 23 Is provided.

FIG. 2 is a flowchart showing a procedure up to displaying a reconstructed image in the X-ray CT apparatus 100. In step S1, scan data is collected by helical scan. That is, the scan data is collected while moving the subject linearly in the body axis direction with respect to the X-ray detector and rotating the X-ray tube around the subject. In step S2, a three-dimensional image is created based on the scan data and displayed on the screen of the display device. An example of the three-dimensional image display processing will be described with reference to FIG.

FIG. 3 is a flowchart of the orthogonal scout image display processing which is an example of the three-dimensional image display processing. In step R1, scan data at a view angle of 0 ° among the scan data is arranged in the order of the position in the body axis direction to create a scout image at 0 °. FIG. 4 conceptually shows an example of a 0 ° scout image G0. The technique for creating a scout image from scan data is disclosed in Japanese Utility Model Laid-Open No. 5-21908. In step R2, scan data at a view angle of 90 ° in the scan data are arranged in the order of the position in the body axis direction to create a 90 ° scout image. In FIG.
An example of a 90 ° scout image G90 is conceptually shown. In step R3, an oblique view of the image (orthogonal scout image) obtained by combining the scout image of 0 ° and the scout image of 90 ° (oblique scout image) is created and displayed on the screen of the display device. FIG. 6 illustrates a perspective image Gg.

Returning to FIG. 2, in step S3, a reconstruction plane is set on the three-dimensional image. For example, as shown in FIG. 7, the reconstruction plane RP is displayed on the perspective image Gg, and the desired reconstruction plane is set by changing its position and angle.

Returning to FIG. 2, in step S4, the pixels included in the reconstruction plane are grouped for each axial plane. For example, as shown in FIG. 8, a group of pixels vx on the intersection line between the reconstruction plane RP and one axial plane APi is represented by:
The group corresponds to the axial plane APi. Here, if the interval between the axial planes APi is large, the reconstruction plane RP
The interval between the upper crossing lines becomes wider, and pixels on the reconstruction plane RP fall out (some pixels do not belong to any of the axial planes APi). Further, when the interval between the axial planes APi is narrow, the interval between the intersection lines on the reconstruction plane RP becomes narrow, and the pixels on the reconstruction plane RP overlap with each other.
Pixels belonging to i appear). Therefore, an appropriate interval between the axial planes APi such that pixels on the reconstruction plane RP do not have omissions and no overlaps are obtained, or interpolation processing or smoothing processing is performed after allowing some omissions or overlaps. Need to be added.

Returning to FIG. 2, in step S5, each axial image is reconstructed.
Only pixels in a group corresponding to the axial image are set. For example, as shown in FIG.
... Only the pixel data of some pixels vx1,... Of the API are calculated.

Returning to FIG. 2, in step S6, as shown in FIG. 10, for example, the calculated pixel data is combined to create a reconstructed image RG.

According to the above X-ray CT apparatus 100, FIG.
In step S3, a three-dimensional image is displayed on the screen.
Since the operator sets the reconstructed surface using the display of the three-dimensional image, the positional relationship between the subject and the reconstructed surface can be intuitively grasped, and even an unskilled operator can easily and accurately reconstruct the reconstructed surface. Can be set. Step S5 in FIG.
Therefore, instead of calculating the pixel data of all the pixels on the axial plane, only the data of the pixels included in the axial plane and on the reconstruction plane are calculated, so that there is no useless calculation and the processing time is reduced. I can do it.

In the above embodiment, a pseudo three-dimensional image based on an orthogonal scout image is used as a three-dimensional image. However, a three-dimensional model in which the number of voxels is thinned out is created and a three-dimensional image based on the model is used. Good. Alternatively, a surface model having only surface voxels may be created, and a three-dimensional image based on the surface model may be used.

[0025]

According to the reconstruction plane setting method and the reconstruction plane setting apparatus of the present invention, the operator sets the reconstruction plane by using the display of the three-dimensional image. The positional relationship between the constituent surfaces can be intuitively grasped, and even an unskilled operator can easily and accurately set the reconfigured surface. Further, according to the reconstructed image creating method of the present invention, instead of calculating the pixel data of all the pixels on the axial plane, only the data of the pixels included in the axial plane and on the reconstructed plane are calculated. This eliminates useless calculations and shortens the calculation time. Further, according to the X-ray CT apparatus of the present invention, it is possible to easily and accurately set the reconstructed surface and to shorten the calculation time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an X-ray CT apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure for creating and displaying a reconstructed image by the X-ray CT apparatus of FIG. 1;

FIG. 3 is a flowchart showing a procedure for creating and displaying a pseudo three-dimensional image based on an orthogonal scout image.

FIG. 4 is a schematic diagram of a scout image at 0 °.

FIG. 5 is a schematic view of a 90 ° scout image.

FIG. 6 is an explanatory diagram of a pseudo three-dimensional image based on an orthogonal scout image.

FIG. 7 is an explanatory diagram of a method for setting a reconstructed surface using the pseudo three-dimensional image of FIG. 6;

FIG. 8 is an explanatory diagram of pixels on the intersection line between the reconstruction plane and the axial plane.

FIG. 9 is an explanatory diagram of pixels for which data is actually calculated on each axial surface.

FIG. 10 is a conceptual diagram of a reconstructed image obtained by synthesizing data.

FIG. 11 is a flowchart showing a procedure for creating and displaying a reconstructed image by a conventional X-ray CT apparatus.

FIG. 12 is a conceptual diagram of a number of axial images arranged in the body axis direction.

FIG. 13 is a schematic diagram of one axial image.

FIG. 14 is an explanatory diagram of a method for setting a reconstructed surface using an axial image.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 X-ray CT apparatus 1 Operation console 3 Central processing unit 10 Imaging table 20 Scanning gantry G0 0 ° scout image G90 90 ° scout image Gg Pseudo three-dimensional image RP reconstruction plane vx pixel RG reconstruction image APi axial plane

Claims (7)

[Claims] 1. An object is scanned to collect scan data, a three-dimensional image is created and displayed based on the scan data, and an operator sets a reconstructed surface using the display of the three-dimensional image. A reconstructed surface setting method. 2. The reconstruction plane setting method according to claim 1, wherein two scout images having different projection plane angles are combined, and a perspective image obtained by projecting the scout image on a plane intersecting both scout images is obtained. A reconstructed surface setting method characterized by creating and displaying a two-dimensional image. 3. The method according to claim 1, wherein a three-dimensional model having a small number of voxels is created, and an image obtained by projecting the three-dimensional model on one surface is created as the three-dimensional image. A reconstructed surface setting method characterized by displaying. 4. The method according to claim 1, wherein a surface model is created, and an image as if the surface model was projected on one surface is created and displayed as the three-dimensional image. Reconstruction plane setting method. 5. A three-dimensional image creating and displaying means for creating and displaying a three-dimensional image based on scan data collected by scanning a subject, and an operator using a display of the three-dimensional image to display a reconstructed surface. A reconfiguration surface setting means for setting a reconfiguration surface. 6. An X-ray detector that rotates an X-ray tube around a subject and moves the subject relative to the X-ray tube in the direction of the rotation axis while transmitting X-rays transmitted through the subject. In the operation of collecting the scan data detected by the above, causing the operator to set the reconstruction plane, and performing the reconstruction of the axial image based on the scan data, the calculation is performed on the reconstruction plane included in the axial image and Only the pixel data of
A method of creating a reconstructed image, comprising combining the obtained pixel data of each group to create an image of the reconstructed surface. 7. An X-ray detector for rotating an X-ray tube around a subject and moving the subject relative to the X-ray tube in the direction of the rotation axis while transmitting the X-rays through the subject. Data collecting means for detecting and collecting scan data in step (3), and creating and displaying a three-dimensional image based on the scan data (3)
Dimensional image creation and display means, reconstructed surface setting means for allowing an operator to set a reconstructed surface using the display of the three-dimensional image, and the axial image in a calculation for reconstructing an axial image based on the scan data Reconstruction calculating means for obtaining only the data of the pixels on the reconstructed plane set in the image, and image creation for composing the obtained data of the pixels of each group to create an image of the reconstructed plane X-ray CT apparatus comprising: