JP2009276163A - X-ray tomographic image photographic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray tomographic image photographic system, capable of rapidly obtaining the three-dimensional data of high resolving power of a required cross section or region. <P>SOLUTION: The tomographic image of high resolving power, only of the required region on a target W can be rapidly displayed, by providing a low resolving power, reconstructing operation means 15 for obtaining the three-dimensional image data of the target W by the reconstituting operation of low resolving power by using X-ray projection data obtained by thinning out, for example, the X-ray projection data of some angles among the X-ray projection data at each predetermined angle stored in a memory means 14 and a high resolving power reconstituting operation means 16 for performing the reconstituting operation of high resolving power, by using the X-ray projection data stored in the memory means with respect to the surface indicated on the tomographic image, based on the reconstituting operation result of the low resolving power and the region thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an industrial X-ray tomography apparatus, and more specifically, X-ray projection data of an object is collected three-dimensionally, and a tomogram along an arbitrary cross section is constructed using the projection data. The present invention relates to an X-ray tomographic imaging apparatus that can be displayed.

  In an X-ray tomographic imaging apparatus, generally, a sample stage for placing an object is provided between an X-ray generator and an X-ray detector, and a pair of the X-ray generator and X-ray detector, a sample stage, Is rotated by a relatively small angle to collect X-ray projection data of the object from many directions, filter the data, etc., and then perform back projection to obtain the tomographic image of the object. Get a statue.

  In recent years, with the advancement of computer technology, it has become possible to obtain several hundred tomographic images such as helical CT and cone beam CT at a time, and to perform three-dimensional internal observation of an object. . The three-dimensional image information of the object is observed using an MPR (Multi Planer Reconstruction) display or the like. The MPR display is generally a display method for observing the reconstructed three-dimensional data on an arbitrary cross section, and the three-dimensional projection data of the collected object is reconstructed and the arbitrary slice is displayed. It is a method (for example, refer patent document 1).

An example of the MPR display is shown in FIG. 5A is a perspective view of an object, and FIG. 5B is a diagram showing an example of a display screen of a display that displays a tomographic image constructed based on three-dimensional X-ray projection data of the object. It is. In FIG. 5B, CS0 is a tomographic image (original image) along a plane orthogonal to the rotation axis at the time of projection data acquisition (at the time of imaging), and CS1 and CS2 are parallel to the rotation axis and orthogonal to each other. It is an image generally called an oblique image. Further, CS3 is a tomographic image along a plane of an arbitrary angle selected on an oblique image, and is called a double oblique image, and thus obtained by reconstruction calculation using three-dimensional X-ray projection data. It is possible to observe a tomographic image at an arbitrary cross section from the obtained three-dimensional image information. The cross-sectional positions of CS1, CS2 and CS3 are shown in FIG.
JP 2005-300388 A

  By the way, due to technical progress in recent X-ray detectors and the development of storage media such as hard disks, the number of pixels of X-ray projection data, which is the original data for reconstructing tomographic images, has increased, and the amount of data Is increasing dramatically. When the resolution of the original data increases, the number of pixels of the reconstructed image can be increased to achieve high resolution. However, since the reconstruction operation is a three-dimensional coordinate calculation, the number of pixels increases. The calculation amount increases with the third power, and the required time is a problem in achieving high resolution of the tomographic image.

  The present invention has been made in view of such a situation, and an object thereof is to provide an X-ray tomographic imaging apparatus capable of quickly obtaining high-resolution three-dimensional data of a necessary cross section or region.

  In order to solve the above problems, an X-ray tomographic imaging apparatus according to a first aspect of the present invention includes the X-ray generator in a state in which an object is disposed between an X-ray generator and an X-ray detector that are arranged to face each other. An object at a plurality of angles is obtained by irradiating an X-ray and capturing the output of the X-ray detector while relatively rotating the pair of the X-ray detector and the X-ray detector and the object by a predetermined angle. X-ray projection data is collected and stored in the storage means, and the stored X-ray projection data is reconstructed, so that the X-ray tomography apparatus for constructing a tomographic image of the object stores in the storage means The low-resolution reconstruction calculation means for reconstructing the obtained data to obtain low-resolution three-dimensional image information, and the plane and region specified on the image based on the calculation result by the low-resolution reconstruction calculation means The data stored in the means Characterized by that it comprises a high-resolution reconstruction calculation means for constructing a tomographic image of high resolution by configuring.

  In order to solve the same problem, an X-ray tomography apparatus according to a second aspect of the present invention is configured so that the object is disposed between the X-ray generation device and the X-ray detector that are arranged to face each other. Targets at multiple angles are obtained by irradiating X-rays and capturing the output of the X-ray detector while relatively rotating the X-ray generator and X-ray detector pair and the object by a predetermined angle. In an X-ray tomographic imaging apparatus for constructing a tomographic image of an object by collecting X-ray projection data of an object and storing it in a storage means and reconstructing the stored X-ray projection data, the storage means The low-resolution reconstruction calculation means for reconstructing the stored data to obtain low-resolution three-dimensional image information, and the three-dimensional area designated on the image based on the calculation result by the low-resolution reconstruction calculation means The data stored in the storage means By configuring, characterized by that it comprises a high-resolution reconstruction calculation means for obtaining a three-dimensional image information of the high resolution.

  Here, in the first and second aspects of the invention, the low-resolution reconstruction calculating means calculates the number of pixels of the tomographic image reconstructed by the number of pixels of the tomographic image reconstructed by the high-resolution reconstruction calculating means. The X-ray projection data at some angles among the X-ray projection data at a plurality of angles stored in the storage means is used as in the invention according to claim 3. Thus, it is possible to employ a configuration for performing reconstruction calculation.

  Further, in the inventions according to claims 1 and 2, the high-resolution reconstruction calculation means is the X-ray projection data of all angles among the X-ray projection data at a plurality of angles stored in the storage means. It is desirable to employ a configuration (claim 4) for performing a reconstruction operation using.

  In the inventions according to claims 1 and 2, in place of the configuration employed in the invention according to claim 3, the low-resolution reconstruction calculation means is an X-ray projection at each angle stored in the storage means. For the data, an average value or an added value of outputs of a plurality of predetermined pixels adjacent to each other on the X-ray detector is calculated, and the average value or the added value is determined by using the predetermined plurality of pixels as one pixel. It is also possible to employ a configuration (claim 5) used for reconstruction calculation as an output.

  And in this invention, the structure (Claim 6) which employ | adopts the calculation result by the said low-resolution reconstruction calculating means and reconstructs the tomogram along a several different surface mutually is displayed (Claim 6). can do.

  According to the present invention, in this type of industrial X-ray tomography apparatus, high-resolution three-dimensional information is not necessary in all parts of an object, for example, on a plane at an angle of a specific part. It was made in consideration of the fact that there are many usage methods that a high resolution is required for the tomographic image along.

  That is, in the present invention, low-resolution reconstruction calculation means and high-resolution reconstruction calculation means are provided as the reconstruction calculation means, and the low-resolution reconstruction calculation means stores the three-dimensional projection data collected by photographing. Among them, for example, as in the invention according to claim 3, when projection data is collected at a part of projection data at a plurality of angles, for example, every angle α, for example, only X-ray projection data at an angle 4α, Is used to obtain low-resolution three-dimensional image information in a short time and display it on a display. On the other hand, in the high-resolution reconstruction calculation means, only the planes and areas designated by the operator on the image based on the reconstruction calculation result by the low-resolution reconstruction calculation means are all taken as in the invention according to claim 4, for example. High-resolution image information is obtained by performing reconstruction calculation using X-ray projection data at an angle of.

  The high-resolution reconstruction calculation is performed only for the designated plane and region in the invention according to claim 1, and only the designated three-dimensional region in the invention according to claim 2. Even if an image or three-dimensional image information is obtained, the area to be calculated is narrower than the entire conventional area, so that the required time does not become longer, thereby reducing the amount of X-ray projection data. Even if it increases, the reconstruction operation at high resolution is minimal and the increase in required time can be suppressed.

  As another example of the low-resolution reconstruction calculation method using the X-ray projection data stored in the storage means, as in the invention according to claim 4, a predetermined plurality of adjacent ones on the X-ray detector A method of calculating an average value or an added value of pixels, for example, four outputs, treating a set of these four pixels as one pixel, and using the average value or the added value as an output for a reconstruction operation. It can also be adopted. Further, the technique of the invention according to claim 4 and the technique of the invention according to claim 3 can be used in combination.

  According to the present invention, even if three-dimensional X-ray projection data is collected at a high resolution, only a part of the data is used for the reconstruction operation, so that relatively low-resolution three-dimensional image information is obtained. By obtaining a desired plane and region on the image, or by specifying a three-dimensional region, a high-resolution reconstruction calculation is performed only for the specified region, and high-resolution image information is obtained. While obtaining high-resolution image information of a necessary area, the time required for reconstruction calculation can be greatly shortened, and prompt observation is possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing a mechanical configuration and a block diagram showing a functional configuration of a control device.

  The X-ray generator 1 is arranged so that its X-ray optical axis L is oriented in the horizontal direction, and the X-ray detector 2 is arranged facing the X-ray generator 1 in the horizontal direction. The X-ray generator 1 is supplied with a tube voltage and a tube current according to a signal from the X-ray controller 11 to generate cone beam X-rays. The X-ray detector 2 is a two-dimensional X-ray detector in which pixels are arranged two-dimensionally.

  Between the X-ray generator 1 and the X-ray detector 2, a rotary stage 3 for mounting the object W is disposed. The rotation stage 3 rotates about a rotation axis R along a vertical direction orthogonal to the X-ray optical axis L. The rotary stage 3 is movable in three orthogonal directions including the X-ray optical axis L. The movement in each axial direction and the rotational operation around the rotational axis R are controlled by an axis. It is controlled by a drive control signal supplied from the unit 12.

  When collecting X-ray projection data of the object W, that is, CT imaging, each time the rotation stage 3 is rotated by a predetermined minute angle α while the object W is mounted on the rotation stage 3 and irradiated with X-rays. Further, it is performed by taking in the output of the X-ray detector 2. Specifically, each pixel output of the X-ray detector 2 at each rotation angle is sequentially stored in the data storage unit 14 via the image data capturing circuit 13 as X-ray projection data at that angle.

  The X-ray projection data at each angle stored in the data storage unit 14 is used for calculation by the low-resolution reconstruction calculation unit 15 as will be described later, and data related to the designated area is high-resolution reconstruction. It is used for calculation by the calculation unit 16. The calculation results by the low-resolution reconstruction calculation unit 15 and the high-resolution reconstruction calculation unit 16 are stored in the low-resolution three-dimensional image storage unit 17 and the high-resolution tomographic image storage unit 18, respectively, and through the display control unit 19. It is displayed on the display 20 as a tomographic image.

  X-ray controller 11, axis control unit 12, image data capturing circuit 13, data storage unit 14, low-resolution reconstruction calculation unit 15, high-resolution reconstruction calculation unit 16, low-resolution three-dimensional image storage unit 17, high-resolution The tomographic image storage unit 18 and the display control unit 19 are placed under the control of the system control unit 21, and an operation unit 22 including a mouse, a keyboard, a joystick, and the like is connected to the system control unit 21. By operating the operation unit 22, the rotary stage 3 can be positioned in an arbitrary direction, and a tomographic image to be displayed by MPR display described later or a tomographic image to be subjected to high-resolution reconstruction calculation Various commands such as designation and execution commands can be given. Note that the system control unit 21, the low-resolution reconstruction calculation unit 15, the high-resolution reconstruction calculation unit 16, the display control unit 17, and the like are actually composed mainly of a computer and its peripheral devices, and are installed in installed programs. In order to simplify the explanation, FIG. 1 shows a block diagram for each function.

Next, the operation of the embodiment of the present invention having the above configuration will be described with reference to the flowchart of FIG.
First, the object W is mounted on the rotary stage 3, the rotary stage 3 is positioned so as to obtain a required field of view, and then an imaging start command is given, whereby the angle α of the object W is obtained by the above-described imaging operation. Collect every other X-ray projection data. When the data for 360 ° is obtained, X-ray projection data at every 4α, for example, is picked up among the X-ray projection data at each angle, and the object W is obtained by low-resolution reconstruction calculation using only the data. The low-resolution three-dimensional image information is obtained and stored in the low-resolution three-dimensional image storage unit 17.

  Based on the low-resolution three-dimensional image information, a tomographic image is displayed on the display device 20 by MPR display. An example is shown in FIG. In this example, a tomographic image S0 along a plane orthogonal to the rotational axis R, a tomographic image (oblique image) S1 and S2 parallel to the rotational axis R and along a plane designated by the operator on the tomographic image S0, and A tomographic image S3 along the plane designated by the operator on these oblique images is displayed at a low resolution. The display 20 displays a high-resolution data calculation switch 20a together with these tomographic images. With any one of the tomographic images S0 to S3 displayed in MPR selected, the high-resolution data calculation switch 20a is selected. By operating the switch 20a, the data necessary for reconstructing the tomographic image among the X-ray projection data stored in the data storage unit 14 for the selected tomographic image is left at every angle α. It is constructed by the high-resolution reconstruction calculation used and displayed on the display 20. An example is shown in FIG. In this example, S2 is selected from the tomographic images displayed in FIG. 3A, and a tomographic image PS2 obtained by reconstructing the tomographic image with high resolution is displayed.

  According to the above-described embodiment, the low-resolution low-resolution image obtained by thinning out the projection angle among the X-ray projection data at a plurality of angles collected by imaging is used as the entire three-dimensional image information of the object W. Under the reconstruction calculation, the tomographic image along the plane selected on the displayed image is quickly constructed and displayed. Since it is constructed and displayed, the calculation time is greatly shortened as compared with the conventional case where the three-dimensional image information of the object W is performed by high-resolution reconstruction calculation, and the necessary tomographic image is displayed. Are displayed under high resolution.

  In the above embodiment, a low-resolution tomographic image is displayed by MPR display, and one of the tomographic images is selected to obtain a high-resolution tomographic image as a whole. A region may be further specified on the image, and a high-resolution tomographic image may be constructed only for that region.

  Further, instead of designating a plane and its region for obtaining a high-resolution tomographic image as described above, a three-dimensional region is designated on the low-resolution tomographic image displayed by MPR display, and the designated 3 High-resolution reconstruction calculation may be performed on the dimension region. An example is shown in FIGS. 4A shows a state of MPR display based on the three-dimensional image information obtained by the low-resolution reconstruction calculation, and displays the tomographic images S0 to S3 equivalent to FIG. 3A. An example is shown in which a three-dimensional area is designated using a cursor C on a tomographic image displayed in MPR. On this screen, a high-resolution three-dimensional data creation switch 20b is also displayed.

  With respect to the three-dimensional region designated as described above, high-resolution three-dimensional image information is obtained by high-resolution reconstruction calculation, and based on the high-resolution three-dimensional image information as shown in FIG. MPR display. In this example, based on the high-resolution three-dimensional image information of the designated three-dimensional area, the high-resolution along the same plane as the tomographic images S0 to S3 in the low-resolution MPR display of FIG. The tomographic images PS0 to PS3 are displayed.

  Also in this embodiment, as in the previous example, the time required to obtain a high-resolution tomographic image of a required part can be significantly shortened compared to the conventional case.

  As to the low-resolution reconstruction calculation method, when X-ray projection data for each angle α is collected during imaging as described above, only the X-ray projection data for each angle 4α is used, and the pixel output of the X-ray detector is used. For example, a method of averaging or adding the outputs of four pixels adjacent to each other, treating the set of these four pixels as one pixel, and using the output value as the above average value or addition value is also adopted. In addition to the method of reducing the number of pixels of the X-ray projection data used for the reconstruction calculation as described above, the number of pixels of the tomographic image to be reconstructed is increased. A method of reducing the number of pixels of the tomographic image obtained by the resolution reconstruction calculation can also be employed. However, regardless of which method is employed, it is desirable to obtain three-dimensional image information of the entire object by low-resolution reconstruction calculation.

  The apparatus configuration is not particularly limited. In addition to the configuration in which the rotary stage provided between the X-ray generator and the X-ray detector is rotated as in the above-described embodiment, the X-ray generator And a configuration in which a pair of X-ray detectors is rotated around the object.

In the block diagram of embodiment of this invention, it is a figure which writes together and shows the schematic diagram showing a mechanical structure, and the block diagram showing the functional structure of a control apparatus. It is a flowchart showing operation | movement of embodiment of this invention. FIG. 4A is a diagram illustrating a display example in the embodiment of the present invention, FIG. 4A is a diagram illustrating an MPR display state of a tomogram based on a low-resolution reconstruction calculation, and FIG. 4B is a high-resolution reproduction of a specified surface. It is a figure which shows the display state of the tomogram based on a structure calculation. FIG. 6A is a diagram showing a display example in another embodiment of the present invention, and FIG. 5A is a tomographic image MPR display state based on a low-resolution reconstruction calculation, in which a region for performing a high-resolution reconstruction calculation is designated. (B) is a diagram showing an MPR display state of a tomographic image based on a high-resolution reconstruction calculation of a specified area. It is a figure which shows the example of the MPR display of a tomogram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray generator 2 X-ray detector 3 Rotation stage 11 X-ray controller 12 Axis control part 13 Image data acquisition circuit 14 Data storage part 15 Low resolution reconstruction calculation part 16 High resolution reconstruction calculation part 17 Low resolution three-dimensional image Storage unit 18 High-resolution tomographic image storage unit 19 Display control unit 20 Display unit 21 System control unit 22 Operation unit

Claims (6)

In a state where the object is disposed between the X-ray generator and the X-ray detector that are arranged opposite to each other, the pair of the X-ray generator and the X-ray detector and the object are relatively rotated by a predetermined angle. However, by irradiating X-rays and capturing the output of the X-ray detector, X-ray projection data of the object at a plurality of angles is collected and stored in the storage means, and the stored X-ray projection data is stored. In an X-ray tomography apparatus for constructing a tomogram of an object by reconstructing,
Low-resolution reconstruction calculation means for reconstructing data stored in the storage means to obtain low-resolution three-dimensional image information, a plane designated on the image based on the calculation result by the low-resolution reconstruction calculation means, and An X-ray tomographic imaging apparatus comprising high-resolution reconstruction calculation means for constructing a high-resolution tomographic image by reconstructing data stored in the storage means for an area. In a state where the object is disposed between the X-ray generator and the X-ray detector that are arranged opposite to each other, the pair of the X-ray generator and the X-ray detector and the object are relatively rotated by a predetermined angle. However, by irradiating X-rays and capturing the output of the X-ray detector, X-ray projection data of the object at a plurality of angles is collected and stored in the storage means, and the stored X-ray projection data is stored. In an X-ray tomography apparatus for constructing a tomogram of an object by reconstructing,
Low-resolution reconstruction calculation means for reconstructing the data stored in the storage means to obtain low-resolution three-dimensional image information, and three-dimensional designated on the image based on the calculation result by the low-resolution reconstruction calculation means An X-ray tomographic imaging apparatus comprising high-resolution reconstruction calculation means for obtaining high-resolution three-dimensional image information by reconstructing data stored in the storage means for an area.   The low-resolution reconstruction calculation means performs a reconstruction calculation using X-ray projection data at some angles among X-ray projection data at a plurality of angles stored in the storage means. The X-ray tomographic imaging apparatus according to claim 1 or 2.   The high-resolution reconstruction calculation means performs a reconstruction calculation using X-ray projection data at all angles among X-ray projection data at a plurality of angles stored in the storage means. The X-ray tomographic imaging apparatus according to any one of claims 1, 2, and 3.   The low-resolution reconstruction calculation unit is configured to calculate an average value or an addition value of outputs of predetermined pixels adjacent to each other on the X-ray detector with respect to the X-ray projection data at each angle stored in the storage unit. 5. The X-ray according to claim 1, wherein the predetermined plurality of pixels are used as one pixel, and the average value or the addition value is used as an output for a reconstruction operation. Tomographic imaging device.   The tomographic images along a plurality of different planes are reconstructed using the calculation result by the low-resolution reconstruction calculation means and simultaneously displayed on a display. 5. The X-ray tomographic imaging apparatus according to 5.