JP4600661B2 - X-ray CT system - Google Patents

Description

  The present invention relates to an industrial X-ray for obtaining a tomographic image of non-destructive investigation of internal defects and internal structures of industrial products such as electronic components mounted on a printed wiring board. The present invention relates to a CT apparatus.

  In general, an X-ray CT apparatus for industrial use is orthogonal to the X-ray optical axis L between an X-ray source 71 and an X-ray detector 72 arranged to face each other, as shown in a schematic plan view in FIG. A rotating stage 73 that rotates around an axis R is disposed, and X-rays are rotated each time the rotating stage 73 is rotated by a predetermined minute angle while irradiating X-rays with the subject W held on the rotating stage 73. X-ray transmission data from the detector 72 is captured. Then, using the acquired X-ray transmission data, a tomographic image of the subject W along a plane orthogonal to the rotation axis R of the rotary stage 73 is reconstructed.

  As is clear from FIG. 9, the tomographic image area that can be reconstructed using the X-ray transmission data measured by the X-ray detector 72 is inside the circle represented by C in FIG. The tomographic image reconstructed using the X-ray transmission data taken in the setting of FIG. 9 is circular. Further, when imaging a part of the subject W as a region of interest, the positional relationship among the X-ray source 71, the X-ray detector 72, and the rotary table 73 is adjusted so that the region of interest falls within the field of view. In this case, the region of interest is also set as a circle (see, for example, Patent Document 1).

  Further, in a cone CT apparatus that outputs cone beam-shaped X-rays from the X-ray source 71 and detects the transmitted X-rays by the two-dimensional X-ray detector 72, X-ray transmission data obtained by one CT imaging is obtained. The area of the tomographic image that can be reconstructed by using a shape is generally a cylinder. When a region of interest and a slice range (range in the direction of the rotation axis R to be reconstructed) are set to obtain a three-dimensional image, a circular shape is obtained. A three-dimensional image within a range surrounded by a cylindrical body formed by laminating a plurality of tomographic images is obtained.

Furthermore, in the so-called enlargement reconstruction operation in which CT imaging is performed and, for example, a tomographic image of the entire subject is reconstructed and then a specific part is enlarged and reconstructed on the tomographic image, the region to be enlarged and reconstructed is determined. Although the region of interest is set, the region of interest is set as a square or a circle, and the enlarged reconstruction region is set by changing the position, size, and orientation of the square. In the case of a three-dimensional image, it becomes a rectangular parallelepiped having the square as a cross-sectional shape and the slice range as a height.
JP 2002-310943 A

  By the way, in the setting of the circular region of interest in the conventional X-ray CT apparatus as described above, there is a region in which the subject does not exist in the reconstruction region, unless the circular region is filled with the cross section of the subject. Will do. For example, when a printed circuit board is used as a subject, generally, as illustrated in FIG. 9, it is generally performed to shoot by irradiating X-rays from the side with the substrate being the subject W standing up. However, in this case, as shown in FIG. 10, there are many areas occupied by air other than the tomographic image W ′ of the subject W in the reconstruction calculation area C, and the reconstruction calculation time for the space area is wasted. It has become.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an X-ray CT apparatus capable of efficiently performing a reconstruction operation and thereby shortening the reconstruction operation time. .

In order to solve the above-described problems, an X-ray CT apparatus according to the present invention has a subject held between an X-ray source and an X-ray detector arranged opposite to each other, and a rotation axis orthogonal to the X-ray optical axis is centered. And a tomographic image of the subject along the plane perpendicular to the rotation axis using the X-ray transmission data of the subject taken at every predetermined angle while rotating the rotary stage. In the X-ray CT apparatus provided with the reconstruction calculation means for reconstructing the image, the drawing for drawing the closed loop of the shape surrounding the contour of the subject on the tomographic image preliminarily reconstructed using the X-ray transmission data comprising means, the reconstruction operation unit, its characterized by being configured to reconstruct calculating a tomographic image of the inside only the inner region of the drawn closed loop as a region of interest (claim 1 .

Here, in the present invention, the drawing means has a function of drawing a second closed loop having an arbitrary shape inside the closed loop, and the reconstruction calculating means has an annular shape surrounded by these two closed loops. It is possible to configure so that the tomographic image only in the region is reconstructed and calculated with the region as the region of interest.

In the present invention, instead of the drawing means, an image that automatically forms a closed loop that surrounds the subject image based on the luminance information on the preliminarily reconstructed tomographic image. comprising a processing unit, the reconstruction operation means can (claim 3) configured to reconstruct calculating a tomographic image of the inside only the inner region of the formed closed loop as a region of interest.

In addition to the closed loop including the subject image, in addition to the closed loop that includes the subject image, the image processing means also includes a portion that is easy to transmit X-rays. A function of automatically forming a second closed loop to be included, and the reconstruction calculation means performs a reconstruction calculation of a tomographic image only within the region, with the annular region surrounded by the two closed loops as a region of interest. It can also be configured (claim 4).

The present invention further includes an optical camera that photographs the subject on the rotary stage from a direction along the rotational axis, and a display unit that displays an appearance image of the subject by the optical camera, and the drawing unit or the image processing The means may employ a configuration (drawing 5) that draws or automatically forms a closed loop on the appearance image of the subject displayed by the display means, instead of the preliminarily reconstructed tomographic image. it can.

The invention according to claim 6 extends the idea of the present invention in three dimensions, and holds an object between an X-ray source and an X-ray detector arranged opposite to each other and orthogonal to the X-ray optical axis. A rotating stage that rotates around the rotating axis is disposed, and the X-ray transmission data of the subject captured at a predetermined angle while rotating the rotating stage is used along a plane orthogonal to the rotating axis. In an X-ray CT apparatus provided with reconstruction calculation means for reconstructing a three-dimensional image composed of a plurality of tomographic images of a subject, on the three-dimensional image preliminarily reconstructed using the X-ray transmission data A three-dimensional region designating unit that designates a three-dimensional region having a shape surrounding the subject image, and the reconstruction calculation unit reconstructs a tomographic image only inside the specified three-dimensional region as a region of interest. Characterized by It is.

In this three-dimensionally expanded invention, instead of the specifying means, a drawing means for drawing a closed loop having a shape surrounding the contour of the subject on an arbitrary tomographic image of the three-dimensional images preliminarily reconstructed. And a slice range setting means for setting the height in the direction of the rotation axis of the column having the closed loop as a cross-sectional outline, and the reconstruction calculation means reconstructs a tomographic image of only the inner region of the column. It is possible to configure so as to perform configuration calculation (claim 7).

Further, instead of the drawing means according to claim 7, on the arbitrary tomographic image of the preliminary reconstructed three-dimensional image , the shape surrounding the contour of the subject based on the luminance information And an image processing means for automatically forming a closed loop, wherein the slice range setting means is configured to set the height of the column having the automatically formed closed loop as a cross-sectional contour. ) Is possible.

Here, instead of the image processing means in the invention according to claim 8 described above, based on the luminance information of all the tomographic images constituting the preliminarily reconstructed three-dimensional image, It is possible to suitably employ a configuration provided with image processing means for automatically forming a closed loop having a shape surrounding the contour of the subject (claim 9).

  The drawing unit according to claim 7, further comprising: an optical camera that photographs a subject on the rotary stage from a direction along the rotation axis; and a display unit that displays an appearance image of the subject by the optical camera. The image processing unit according to 8 is configured to draw a closed loop on the appearance image of the subject displayed by the display unit, instead of an arbitrary tomographic image of the preliminarily reconstructed three-dimensional image. It can also be configured to form automatically (claim 10).

  Further, the drawing means in the inventions according to claims 7 and 10 has a function of drawing a second closed loop having an arbitrary shape inside the closed loop as described above, and the slice setting means is surrounded by these two closed loops. The height in the direction of the axis of rotation of the cylinder whose cross section is the area is set, and the reconstruction calculation means is configured to reconstruct a tomographic image of only the area in the cylinder. You can also.

Further, as an image processing means in the invention according to claim 8 or 9, when photographing a subject having a portion where X-rays are easily transmitted inside, in addition to a closed loop having a shape surrounding the contour of the subject , the image processing means is located within the closed loop. The slice range setting means has a function of automatically forming a second closed loop including a portion where X-rays are easily transmitted, and the slice range setting means has a region surrounded by these two closed loops in the direction of the rotation axis of the cylinder. And the reconstruction calculating means can be configured to reconstruct and calculate a tomographic image of only the region within the cylinder.

  The tomogram preliminarily reconstructed in the present invention is reconstructed by thinning out both the matrix number and the view number of the X-ray transmission data detected by the X-ray detector. (Claim 12).

  Here, the closed loop drawn or automatically formed so as to include the subject image by the drawing means or the image processing means is not limited to one in the invention according to each of the above claims, and a plurality of spaced loops are separated from each other. It may be a closed loop.

The present invention solves the problem by surrounding a region where a tomographic image is to be formed with a frame having a shape surrounding the contour of a subject and performing reconstruction calculation only on the region within the frame.

That is, in advance preliminarily reconstructed computed tomographic image (claim 1), or appearance images taken subject in a direction along the rotation axis in (Claim 5) Furthermore, enclose the contour of the photographic material by drawing shape of a closed loop, the inner region of the closed loop as a region of interest, when reconstructing a tomographic image only for the region, in a case such as to construct a tomographic image slicing the substrate or the like in its thickness direction, Compared with the conventional reconstruction calculation in a circular area, the time required for the calculation can be greatly reduced.

  Here, for the tomographic image to be preliminarily reconstructed, either the number of X-ray transmission data matrixes or the number of views is further thinned out, and both the number of matrices and the number of views are thinned out as in the invention according to claim 13. By calculating, the time required to reconstruct the preliminary tomographic image can be considerably shortened compared to the time required for reconstructing the tomographic image in the region of interest. Time can be greatly shortened. For example, in the reconstruction calculation of the tomographic image in the region of interest, it is assumed that the matrix is 512 × 512 and the number of views is 600. If it is 1/4 compared to the area of the circular region, the calculation time is 1/4 compared to the conventional case. On the other hand, in the preliminary reconstruction of tomographic images, if a circular area is calculated with a matrix of 256 × 256 and the number of views of 300, 1/8 of the case of calculating the circular area based on the number of data described above. Therefore, even if 1/8 of the overhead for reconstructing the preliminary tomographic image is increased, the total time can be shortened to 1/4 + 1/8, that is, 3/8.

Further, as in the inventions according to claims 3 and 5 , on the preliminary tomographic image or the external appearance image, for example, the contour is extracted by binarization, and the contour is expanded at a prescribed rate, so that the tomographic image is obtained. Alternatively, a closed loop having a shape including the subject image can be automatically formed on the appearance image, and if the closed loop thus formed is used as a region of interest and a reconstruction operation is performed only on the inside thereof, in addition to the above-described operation, The burden on the operator can be reduced.

According to the second and fourth aspects of the present invention, a closed loop having an arbitrary shape is further drawn inside a closed loop that is drawn or automatically created, or a second closed loop is automatically formed along the inner contour of the subject image. Reconstruction calculation of tomograms only in the area surrounded by two closed loops. For example, in applications that require tomograms of only the contour of the subject, reconstruction calculation of only the tomogram of the contour is performed. By doing so, the required time can be further shortened.

The invention according to claim 6 relates to an X-ray CT apparatus for constructing a three-dimensional image, that is, a CT apparatus having a cone CT or a helical scan function, and an object image on a preliminarily reconstructed three-dimensional image. If a three-dimensional area having a surrounding shape is designated so as to perform a reconstruction calculation within that area, the reconstruction calculation time of the three-dimensional image can be shortened.

The invention according to claim 7 is a simplification of the invention according to claim 6, and draws a closed loop having a shape surrounding the contour of the subject on an arbitrary tomographic image of the three-dimensional image, and the slice range. By setting, a tomographic image is reconstructed and calculated for a region in the column that has a closed loop shape as a cross-sectional outline and a slice range as a height.

Further, in the invention according to claim 8, the image of the subject is obtained by image processing on an arbitrary tomographic image on a three-dimensional image instead of the closed loop drawing on the preliminary tomographic image of the invention according to claim 7 . A closed loop having a shape surrounding the outline is automatically formed, and the automatically formed closed loop is used as a cross-sectional outline, and a tomographic image is reconstructed and calculated for a region in the column whose height is a separately set slice range.

In the invention according to claim 9, the image processing means in the invention according to claim 7 automatically forms a closed loop on an arbitrary tomographic image constituting the three-dimensional image, whereas all tomographic elements constituting the three-dimensional image. A closed loop having a shape surrounding the contour of the subject in the image is automatically formed, and the tomographic image is reconstructed for a region in the column whose height is the slice range set separately, with the automatically formed closed loop as a cross-sectional contour. . According to the ninth aspect of the present invention, the region that automatically includes the subject in three dimensions becomes the reconstruction calculation region without the operator selecting a tomographic image.

  The invention according to claim 10 uses an appearance image of a subject by an optical camera instead of the preliminary tomographic image used in the invention according to claim 7 or 8, and draws or automatically forms a closed loop on the appearance image. This is different from these inventions.

  The invention according to claims 11 and 12 further draws a closed loop of an arbitrary shape inside a closed loop that is drawn or automatically created, or automatically forms a second closed loop along the inner contour of the subject image, By constructing the tomographic image of only the region inside the cylinder whose cross-sectional contour is the region surrounded by the two closed loops, the tomographic image of the tomographic image only in the outer part of the subject is needed. The time required for the reconstruction operation is further shortened.

  The invention according to claim 13 prescribes a preliminary tomographic reconstruction calculation method, wherein both the number of matrices and the number of views of the X-ray transmission data are thinned out and preliminary By reconstructing the tomographic image, the time required to increase due to the application of the present invention can be reduced, and the above-described effects can be ensured.

  However, as the tomogram preliminarily reconstructed in the present invention, attention is paid to a tomogram obtained by thinning out only one of the number of matrices and the number of views, or a tomogram once reconstructed. When a region to be accurately set is enlarged and reconstructed, the “preliminarily reconstructed tomographic image” used for setting the region is a tomographic image in which neither the number of matrices nor the number of views is thinned out. The present invention also includes this configuration.

  According to the present invention, compared with a conventional X-ray CT apparatus that sets a circular region of interest, the area to be subjected to reconstruction calculation can be reduced in most subjects, and the time required for the calculation can be shortened. Can do. In particular, when obtaining a tomographic image sliced in the thickness direction using a flat plate member such as a printed circuit board as a subject, the time required for the reconstruction calculation can be greatly shortened as compared with the conventional case.

  Further, in a CT apparatus that constructs a three-dimensional image by cone CT or helical scanning, since a large number of tomographic images are reconstructed, the time shortening effect is increased.

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 system configuration.

  An X-ray detector 2 is disposed opposite to the X-ray source 1, and a rotary stage 3 for mounting the subject W is disposed therebetween. The rotary stage 3 is rotated about a rotation axis R along the z-axis direction orthogonal to the X-ray optical axis L direction (x-axis direction) from the X-ray source 1 and is mutually moved by the stage moving mechanism 4. It can move in the x, y, and z axis directions orthogonal to each other.

  The X-ray source 1 generates cone beam X-rays corresponding to the tube voltage and tube current supplied from the high voltage generator 10, and the high voltage generator 10 is controlled by the X-ray controller 11. The rotary stage 3 and the stage drive mechanism 4 are driven and controlled by a drive signal supplied from the stage controller 12. These X-ray controller 11 and stage controller 12 are placed under the control of the computer 5. Connected to the computer 5 are an operation unit 5b including a mouse and a keyboard for giving various commands to the apparatus, and a display 5a for displaying a tomographic image of the subject W to be described later.

  At the time of CT imaging, the subject W is placed on the rotary stage 3 and irradiated with X-rays, and a rotation signal about the rotation axis R is given to the rotary stage 3 by a drive signal from the stage controller 12 for each minute rotation angle. X-ray transmission data from the X-ray detector 2 is taken into the CT image reconstruction calculation device 6. The CT image reconstruction calculation device 6 stores the 360-degree X-ray transmission data of the subject W captured in this way in a memory, and performs the following preliminary tomographic reconstruction calculation, Used for tomographic reconstruction.

Next, how to set the region of interest in the above embodiment will be described.
First, a preliminary tomographic image is reconstructed and computed by the CT image reconstruction computation device 6. In this preliminary reconstruction calculation, for example, the X-ray transmission data stored in the z-axis direction designated by the operator by operating the operation unit 5b as a slice plane is stored as the number of matrices and the number of views. For example, the tomographic image is reconstructed and displayed on the display 5a. An example of the display is shown in FIG. In this figure, W ′ represents a tomographic image of the subject W. This preliminary tomographic reconstruction calculation region is a region corresponding to the entire field of view of the X-ray detector 2 and is a region represented by C in FIG.

  By operating the operation unit 5b, the operator draws a closed loop CL having an arbitrary shape surrounding the tomographic image on the preliminary tomographic image displayed on the display 5a as shown in FIG. The coordinate information xi and yj in the x-axis direction and the y-axis direction of the region surrounded by the closed loop CL is sent from the computer 5 to the CT image reconstruction calculation device 6.

  The CT image reconstruction calculation device 6 performs tomographic image reconstruction calculation using only the matrix number and the view number of the X-ray transmission data only in the region surrounded by the closed loop CL sent from the computer 5. . The time required for this reconstruction calculation is the same as the area in C compared to the time when the cross-sectional image in the region C corresponding to the entire field of view of the X-ray detector 2 is reconstructed using the same data. Since it is almost directly proportional to the area in the closed loop CL, the required time can be greatly shortened.

  When a three-dimensional image is constructed by setting a slice range, for example, as in a known method, an X-ray fluoroscopic image of the subject W is displayed on the display 5a, and the z-axis direction is displayed on the fluoroscopic image. Set the upper limit position and lower limit position. Thereby, for each slice plane within the set z-axis direction range, the tomographic image in the region surrounded by the closed loop CL is reconstructed, the closed loop CL is taken as the cross-sectional outline, and the columnar body having the slice range as the height. To construct a three-dimensional image.

  Here, in the above embodiment, the region of interest is set by drawing the closed loop CL on the preliminarily reconstructed tomographic image, but the same closed loop CL is drawn on the appearance image of the subject W. Region of interest can be set.

  FIG. 3 shows a configuration example together with a schematic diagram showing a mechanical configuration and a block diagram showing a system configuration. An optical camera 7 mainly composed of a CCD or the like is arranged on the rotation axis R of the rotary stage 3, the subject W mounted on the rotary stage 3 is photographed by the optical camera 7, and the video signal is captured as image data The image is taken into the computer 5 via the circuit 13, and the appearance image thereof, and thus the appearance image of the subject W expressed in a plan view, is displayed on the display 5a. Even when such an appearance image is used, the same effect as the previous example can be obtained particularly in a subject having a uniform cross section such as a printed circuit board. In addition, even if the subject has a non-uniform cross section, the maximum portion in the x and y directions appears in the x and y directions in the external appearance image represented in plan view. By drawing a closed loop as included, a cross-sectional image or a three-dimensional image in which a necessary portion is not lost can be obtained in a shorter time than in the past.

  In each of the above embodiments, the case where the operator draws the closed loop CL on the preliminary tomographic image or the external appearance image has been described. It is also possible to automatically create a closed loop that includes the subject image.

  That is, for example, an example in which a preliminary tomographic image is used will be described. First, as shown in FIG. 4A, the image is binarized from the grayscale information of the preliminary tomographic image W ′ shown in FIG. Image information is obtained, and the contour S of the subject as shown in FIG. Next, the contour S is isotropically expanded on the screen, and hence on the xy plane, and a closed loop CL as shown in FIG. The x and y coordinate information of the automatically formed closed loop CL is supplied to the CT image reconstruction calculation device 6 and the tomographic image is reconstructed and calculated only for the inner region in the same manner as in the previous example. Thus, it is possible to eliminate the need for the operator to perform the closed loop drawing work.

  Such a technique for automatically forming the closed loop CL corresponding to the region of interest by similarly expanding the contour of the subject image can be equally applied even when using an appearance image. In addition, when the subject W is a hollow body or the internal substance is an object that easily transmits X-rays, the contour S illustrated in FIG. 5 can be obtained by binarizing the tomographic image and extracting the contour. However, in this case, it is only necessary to fill the internal gap and form a closed loop CL as shown in FIG.

  Even when the region of interest is set by such an automatically formed closed loop, when a three-dimensional image is constructed, a closed loop that includes a subject image on an arbitrary tomographic image constituting a preliminary three-dimensional image is used. Is automatically formed, and by setting the slice range in the direction of the rotation axis, a three-dimensional image of the region in the column with the closed loop as the cross-sectional contour and the slice range as the height can be obtained.

  In addition, as described above, instead of automatically forming a closed loop on an arbitrary tomographic image constituting a three-dimensional image, a closed loop including all the subject images on all tomographic images constituting the three-dimensional image is automatically performed. In this case, it is possible to set a region that three-dimensionally includes the subject image without the operator selecting an appropriate one tomographic image from the preliminary tomographic images. As a method of automatically forming such a closed loop, for all tomographic images constituting a preliminary three-dimensional image, the grayscale information of each pixel is binarized, and these are superimposed to perform a logical sum (OR) operation, With respect to the image information after the logical sum, a contour is extracted by the method as described above and isotropically expanded to automatically form a closed loop.

  Further, in each of the above embodiments, one closed loop CL is drawn or automatically formed on a preliminary tomographic image or an external appearance image, and a tomographic image of only the inside thereof is set with the inner region as a region of interest. However, another closed loop may be formed in the closed loop, and a region surrounded by these may be used as a region of interest. That is, when the hollow body as illustrated in FIG. 5 or the internal substance is an object that easily transmits X-rays, the outer and inner contours can be obtained as the contour extracted by binarizing the tomographic image. However, as described above, as shown in FIG. 6, the first closed-loop CL1 positioned outside the outer contour with a predetermined gap with respect to the outer contour, as shown in FIG. The second closed loop CL2 positioned further inside with a predetermined gap with respect to the inner contour is automatically formed, and the region surrounded by the closed loops CL1 and CL2 is reconstructed as a region of interest. Good.

  Further, in the case where the subject is not a hollow subject but a solid subject, the subject image W ′ is shown in FIG. The first closed loop CL1 that includes this outside is drawn, and the second closed loop CL2 is drawn inside the contour of the subject image W ′, and the area surrounded by each of these closed loops CL1 and CL2 Can be reconstructed as a region of interest.

  The method of automatically forming or drawing the two closed loops CL1 and CL2 and setting the region of interest as described above can also be used when constructing a three-dimensional image. That is, two closed loops CL1 and CL2 as illustrated in FIGS. 6 and 7 are drawn or automatically formed, and a region surrounded by the two closed loops CL1 and CL2 by setting a slice range in the rotation axis direction. It is possible to configure such that only the region in the cylinder having the cross-sectional outline is reconstructed.

  In each of the above embodiments, an example in which one closed loop having an arbitrary shape is drawn or automatically formed on a preliminary tomographic image or an external appearance image is shown. However, a plurality of closed loops having an arbitrary shape separated from each other are drawn. Alternatively, it is possible to automatically form the region inside each closed loop as a region of interest.

  Furthermore, in forming the reconstruction calculation area of the three-dimensional image in each of the embodiments described above, a closed loop drawn on a preliminary tomographic image or appearance image of a subject, or a closed loop automatically formed on these images, The column specified by the slice range is used as a reconstruction calculation area. However, a three-dimensional image is preliminarily reconstructed and a three-dimensional image of an arbitrary shape is drawn on the three-dimensional image. A reconstruction calculation area can also be specified. In this case, for example, as conceptually shown in FIG. 8, when the cross section of the subject W changes midway, different column bodies CL1 and CL2 are respectively displayed on the three-dimensional image W ′ with the changed portion as a boundary. Combinations and the like can be employed, and such a designation method can simplify the designation work and at the same time greatly reduce the time required for the reconstruction calculation.

In the configuration diagram of the embodiment of the present invention, a schematic diagram showing a mechanical configuration and a block diagram showing a system configuration are shown together. It is a figure which shows the example of a display of the closed loop CL showing the tomographic image of the to-be-photographed object W preliminarily reconstructed by embodiment of this invention, and the region of interest drawn on the image. It is a block diagram of other embodiment of this invention, and is the figure which writes together and shows the schematic diagram showing a mechanical structure, and the block diagram showing a system configuration | structure. It is explanatory drawing of the example of the image processing method by embodiment which forms the closed loop corresponding to a region of interest automatically, (A) is the state which binarized the preliminary tomogram, (B) extracted the outline The state (C) is a diagram showing a state in which a closed loop is automatically formed based on the contour. FIG. 5 is a diagram illustrating an example of a closed loop formed in the case of a hollow subject in an embodiment in which a closed loop corresponding to a region of interest is automatically formed. It is explanatory drawing of the example in the case of forming automatically the area | region enclosed by two closed loops as a region of interest. It is explanatory drawing of the example in the case of drawing the area | region enclosed by two closed loops as a region of interest. It is a conceptual diagram of an example in the case of drawing an arbitrary three-dimensional shape on a preliminary three-dimensional image and setting a three-dimensional region of interest. It is a typical top view which shows the structural example of the conventional X-ray CT apparatus. FIG. 10 is an explanatory diagram of an example of a tomographic image obtained by performing reconstruction calculation using X-ray transmission data in a field of view of an X-ray detector using a printed circuit board as a subject by the X-ray CT apparatus of FIG. 9.

DESCRIPTION OF SYMBOLS 1 X-ray source 2 X-ray detector 3 Rotating stage 4 Moving mechanism 5 Computer 5a Display 5b Operation part 6 CT image reconstruction calculation apparatus 7 Optical camera L X-ray optical axis R Rotating axis W Subject CL, CL1, CL2 Region of interest Closed loop for setting

Claims (13)

Between the X-ray source and the X-ray detector that are arranged to face each other, a rotating stage that holds an object and rotates around a rotation axis orthogonal to the X-ray optical axis is arranged, and the rotating stage is rotated. An X-ray CT apparatus provided with reconstruction calculation means for reconstructing a tomographic image of a subject along a plane orthogonal to the rotation axis using X-ray transmission data of the subject captured at predetermined angles while
On tomogram preliminarily reconstruction operation by using the X-ray transmission data, comprising a drawing means for drawing a closed loop shape surrounding the contours of the subject, the reconstruction operation unit, the drawn closed loop An X-ray CT apparatus configured to reconstruct and calculate a tomographic image only inside the region of interest inside the region. The drawing means has a function of drawing a second closed loop of an arbitrary shape inside the closed loop, and the reconstruction calculating means uses a circular area surrounded by the two closed loops as a region of interest within the area. The X-ray CT apparatus according to claim 1, wherein the X-ray CT apparatus is configured to perform reconstruction calculation on only a tomographic image. Instead of the drawing means, the image processing means for automatically forming a closed loop having a shape surrounding the subject image on the preliminary tomographic image based on the luminance information is provided. The X-ray CT apparatus according to claim 1, wherein the configuration calculation means is configured to reconstruct and calculate a tomographic image only inside the inner region of the formed closed loop as a region of interest. The image processing means includes a closed loop that includes a subject image and a portion that is located within the closed loop and that easily transmits X-rays when photographing a subject having a portion that easily transmits X-rays. The reconstructing calculation means is configured to reconstruct and calculate a tomographic image only within the region of interest as an annular region surrounded by the two closed loops. The X-ray CT apparatus according to claim 3 , wherein: An optical camera for photographing a subject on the rotary stage from a direction along the rotation axis; and a display means for displaying an appearance image of the subject by the optical camera, wherein the drawing means or the image processing means instead of the reconstructed tomographic image calculation, claim 1, characterized in that the draw or automatically forming a closed loop on the exterior image of the subject displayed by the display means, either 2, 3 or 4 1 X-ray CT apparatus according to item . Between the X-ray source and the X-ray detector that are arranged to face each other, a rotating stage that holds an object and rotates around a rotation axis orthogonal to the X-ray optical axis is arranged, and the rotating stage is rotated. Reconstructing calculation means for reconstructing a three-dimensional image composed of a plurality of tomographic images of a subject along a plane orthogonal to the rotation axis, using the X-ray transmission data of the subject captured at predetermined angles. In the X-ray CT system,
A three-dimensional region designating unit for designating a three-dimensional region having a shape surrounding a subject image on a three-dimensional image preliminarily reconstructed using the X-ray transmission data; An X-ray CT apparatus characterized by reconstructing a tomographic image only inside a designated three-dimensional region as a region of interest. Instead of the designating means, a drawing means for drawing a closed loop having a shape surrounding the contour of the subject on an arbitrary tomographic image of the preliminarily reconstructed three-dimensional image, and the closed loop as a cross-sectional contour. A slice range setting unit that sets the height of the column in the direction of the rotation axis is provided, and the reconstruction calculation unit reconstructs a tomographic image of only the inner region of the column. Item 7. The X-ray CT apparatus according to Item 6. 8. A closed loop having a shape surrounding the contour of a subject on an arbitrary tomographic image of the three-dimensional image preliminarily reconstructed based on the luminance information instead of the drawing means according to claim 7. 8. The image processing means for automatically forming the image, and the slice range setting means sets the height of the column having the automatically formed closed loop as a cross-sectional outline . X-ray CT system. Instead of the image processing means, a closed loop having a shape surrounding the contour of the subject on the whole tomographic image is obtained based on the luminance information of all the tomographic images constituting the three-dimensional image preliminarily reconstructed. The X-ray CT apparatus according to claim 8, further comprising an image processing unit that forms automatically. The image forming apparatus according to claim 7, further comprising: an optical camera that photographs the subject on the rotation stage from a direction along the rotation axis; and a display unit that displays an appearance image of the subject by the optical camera. The described image processing means draws or automatically forms a closed loop on the appearance image of the subject displayed by the display means, instead of an arbitrary tomographic image of the three-dimensional images preliminarily reconstructed. The X-ray CT apparatus according to claim 7 or 8, characterized in that:   The drawing unit has a function of drawing a second closed loop having an arbitrary shape inside the closed loop, and the slice range specifying unit performs the rotation of the cylindrical body having a cross-sectional outline in a region surrounded by the two closed loops. The X-ray CT apparatus according to claim 7 or 10, wherein a height in an axial direction is set, and the reconstruction calculation means performs a reconstruction calculation on a tomographic image of only a region in the cylinder. The image processing means includes a closed loop having a shape surrounding the outline of the subject and a portion where the X-ray is easily transmitted in addition to the closed loop surrounding the contour of the subject when photographing a subject having a portion where X-rays are easily transmitted. And a function of automatically forming a second closed loop, wherein the slice range setting means sets a height in a direction of the rotation axis of the cylindrical body having a cross-sectional contour in a region surrounded by the two closed loops, The X-ray CT apparatus according to claim 8 or 9, wherein the reconstruction calculation means performs a reconstruction calculation on a tomographic image of only a region within the cylinder.   The tomographic image to be preliminarily reconstructed is reconstructed by thinning out the number of matrixes and the number of views of X-ray transmission data detected by the X-ray detector. The X-ray CT apparatus according to 4, 5, 6, 7, 8, 9, or 12.

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