JP4577312B2 - X-ray CT apparatus and X-ray CT method - Google Patents

Description

  The present invention relates to an industrial X-ray CT apparatus and an X-ray CT method for obtaining a tomographic image in order to investigate, for example, an internal defect or an internal structure of an industrial product such as an electronic component in a non-destructive manner.

In an industrial X-ray CT apparatus, generally, a rotary stage that rotates around an axis orthogonal to the X-ray optical axis is arranged between an X-ray source and an X-ray detector that are arranged opposite to each other, and the rotation is performed. X-ray transmission data from the X-ray detector is taken in each time the rotary stage is rotated by a predetermined minute angle while irradiating X-rays with the subject held on the stage. Then, using the acquired X-ray transmission data, a tomographic image of the subject along a plane orthogonal to the rotation axis of the rotary stage is reconstructed (see, for example, Patent Document 1). Here, the rotary stage is normally movable in the direction of the X-ray optical axis (x-axis direction) and the direction orthogonal to it (y and z-axis directions) by a moving mechanism, and on the rotary stage. Also known is an apparatus including an xy table for moving a subject in a biaxial direction (x and y axis directions) orthogonal to the rotation axis.
Japanese Patent Publication, JP-A No. 2004-117024

  By the way, in the industrial X-ray CT apparatus as described above, for example, when obtaining a tomographic image such as the vicinity of a semiconductor chip mounted on a circuit board, it is desired to increase the magnification as much as possible or as bright as possible. It is necessary to bring the subject as close as possible to the X-ray source for reasons such as obtaining a tomographic image. In addition, since it is necessary to rotate the subject on the rotary stage during CT imaging, the operator can set the X through the observation window while rotating the rotary stage with the subject mounted on the rotary stage prior to actual CT imaging. The problem is that the position of the rotary stage is adjusted while checking the distance to the radiation source, and the rotary stage is brought close to the position where the subject interferes with the X-ray source, and the work is complicated. is there.

  In an apparatus in which an xy table is provided on the rotary stage and a desired position on the subject can be moved to the vicinity of the rotation center, the above adjustment operation is performed again after the xy table is moved. Therefore, it is necessary to confirm whether or not the X-ray source does not interfere with the X-ray source.

  Furthermore, in the case of so-called half-scan imaging in which the subject is rotated by a little over half rotation (actually 180 ° + corresponding to the X-ray spread angle) and reconstructed by CT imaging, the subject is further X-rayed. This is effective when the observation site is deviated from the center of the subject, especially when observing a solder joint such as an IC package on a printed wiring board. In this case, the rotation of the subject is effective. Care must be taken in setting the orientation of the object and the distance between the subject and the X-ray source.

  Needless to say, in order to obtain an intended tomographic image, X-ray transmission data of all points on the tomographic image is necessary. However, the rotation stage for the X-ray source and the X-ray optical axis of the X-ray detector are used. Depending on the shooting magnification based on the position in the direction, the condition may not be satisfied. In the X-ray CT apparatus, before collecting X-ray transmission image data of a subject, the subject is placed on a rotating stage and rotated one time while irradiating X-rays, and an intended tomographic image is obtained from every X-ray fluoroscopic image. It is necessary to check whether or not the subject is placed at a position where the image can be obtained, and depending on the result, the position needs to be changed.

  The present invention has been made to solve the problems in the conventional industrial X-ray CT apparatus, and the main problem is that it can prevent interference with the X-ray source during rotation of the subject, and the operator before CT imaging. It is an object to provide an X-ray CT apparatus and an X-ray CT method that can eliminate the confirmation work performed by rotating a rotary stage.

  Another object of the present invention is to provide an X-ray CT apparatus that requires no special consideration by the operator regarding the rotation direction of the rotary stage in addition to the distance between the subject and the X-ray source even when half-scan is selected. There is to do.

  Still another object of the present invention is to provide an X-ray CT apparatus capable of intuitively grasping whether or not an intended tomographic image can be obtained.

In order to solve the main problems described above, the X-ray CT apparatus of the present invention has a rotation axis that is orthogonal to the X-ray optical axis while holding a subject between an X-ray source and an X-ray detector that are arranged to face each other. The subject along a plane orthogonal to the rotation axis is arranged using a rotation stage that rotates as a center and using the X-ray transmission data of the subject taken at predetermined angles while rotating the rotation stage. An X-ray CT apparatus having a reconstruction calculation unit for reconstructing a tomographic image of an optical camera that captures the subject on the rotary stage from a position on or near the rotation axis of the rotary stage, and the optical camera An image processing unit that obtains information related to the shape, size, and position of the subject from the photographed appearance image of the subject, and the image processing unit. Information using a interference monitoring unit for monitoring the interference between the object and the X-ray source during rotation of the rotary stage, the X-ray optical axis direction of the X-ray source and the X-ray detector and the rotary stage And a CT imaging region calculation unit for calculating a region where CT imaging is possible with the rotation axis as the center, and information relating to the size of the light receiving surface of the X-ray detector, and the CT imaging region calculation unit It is characterized by having a display unit that displays the area calculated by the above on a display device superimposed on the subject image taken by the optical camera .

  Here, as a specific configuration of the interference monitoring unit according to the present invention, the position of the X-ray source and the rotary stage, and the subject and the above when the rotary stage is rotated based on the information obtained by the image processing unit. It is determined whether or not the X-ray source interferes, and in the case of interference, a warning is given to that effect, or similarly, whether the subject and the X-ray source interfere when the rotary stage rotates. It is possible to adopt a configuration that discriminates whether or not to interfere with the rotation of the rotary stage when there is interference.

  In the X-ray CT apparatus, when the half scan is selected, the interference monitoring unit sets the rotation direction of the rotary stage with respect to the X-ray source without causing the subject to interfere with the X-ray source. It is also possible to adopt a configuration in which interference monitoring is performed by limiting the rotation stage to a direction in which the rotary stage can be approached more.

  In the present invention, instead of the interference monitoring unit, using the information obtained by the image processing unit, the rotation axis of the rotary stage is closest to the X-ray source, and the rotation stage A configuration including a rotary stage position setting unit that sets the position of the rotary stage at which the subject does not interfere with the X-ray source during rotation can also be employed.

  Even in the X-ray CT apparatus provided with the rotary stage position setting unit, when the half scan is selected, the rotary stage position setting unit does not interfere with the rotation direction of the rotary stage so that the subject does not interfere with the X-ray source. It is possible to adopt a configuration in which the rotation stage is limited to a direction in which the rotation stage can be approached with respect to the X-ray source and the position of the rotation stage is set. It is not necessary for the operator to consider the direction of rotation of the subject, and other problems of the present invention can be solved.

In the above X-ray CT apparatus includes a control unit for moving the X-ray detector or the subject in conjunction when changing the size of the area displayed on the upper Symbol display unit in the X-ray optical axis direction It is preferable to employ a configuration including

Also, X-ray CT apparatus of the present invention, by using the information obtained by the above-outs image processing unit, and includes a subject evacuation unit for moving the object outside the field of view of the X-ray detector when an air calibration of the X-ray Preferably it is.

  The present invention captures a subject on a rotating stage with an optical camera from or near its rotation axis, obtains information on the shape, size, and position of the subject with respect to the rotation axis from the appearance image of the subject, In the X-ray CT apparatus, it is monitored whether the subject interferes with the X-ray source when the rotary stage rotates, or the rotary stage is positioned at a position where the subject is closest to the X-ray source without interference. , Trying to solve the main problem.

  That is, by photographing an object held on the rotary stage with an optical camera on or near the rotation axis, the shape and size of the object and position information on the rotation axis of the rotation stage can be obtained. From these pieces of information, it is possible to determine whether or not the object interferes with the X-ray source when the subject is rotated at the current position of the rotary stage (position of the rotation axis). In the X-ray CT apparatus, an alarm is issued when it is determined that interference occurs, or monitoring such as prohibition of rotation of the rotary stage is performed.

  In the X-ray CT apparatus, based on the same information, the rotation axis of the rotary stage is closest to the X-ray source, and the position where the subject does not interfere with the X-ray source, that is, the imaging magnification and brightness are maximized. Position automatically.

  Such monitoring or positioning operation eliminates the need for confirmation work and repositioning work for the presence of interference prior to CT imaging.

  In the X-ray CT apparatus, when half scan is selected, the direction of rotation of the rotary stage is determined from the appearance image of the subject on the rotary stage by determining the direction in which the subject can approach without interfering with the X-ray source. Is limited to that direction, and then monitoring or positioning of the rotary stage is performed.

  Further, in the X-ray CT apparatus, in addition to the above-described interference monitoring or the function of setting the position of the rotary stage to the optimum position, the positional relationship among the X-ray source, the X-ray detector and the rotary axis of the rotary stage is used. Thus, an area capable of CT imaging can be calculated by geometric calculation, and the calculated area is superimposed on the appearance image of the subject by the optical camera to display X-rays prior to CT imaging. In addition, it is possible to intuitively grasp whether or not an intended tomographic image can be obtained without rotating the rotary stage and checking the fluoroscopic image every moment. By combining this function with the function of monitoring the interference of the subject with the X-ray source or the automatic positioning function of the rotary stage, it is possible to greatly reduce the work prior to the operator's CT imaging. In addition, it is possible to quickly determine whether or not a tomographic image covering an intended region can be obtained in a state where the rotary stage is as close as possible to the X-ray source by the function of the interference monitoring unit or setting unit. Therefore, when it is not possible to cover, it is possible to use the rotating stage away from the X-ray source starting from the closest position.

      Further, in the X-ray CT apparatus, by using the positional relationship between the X-ray source, the X-ray detector, and the rotation axis of the rotary stage as described above, the CT imaging region is calculated by geometric calculation, The calculated area is displayed so as to be superimposed on the appearance image of the subject by the optical camera, and further, the X-ray detector or the subject is linked to the X-ray when the size of the displayed area is changed. Changing the imaging region desired by the operator by moving in the optical axis direction, that is, by controlling the X-ray detector or the subject so that the region intended for imaging falls within the actual CT imaging region. Can be performed intuitively so that the subject does not interfere with the X-ray source during imaging. Therefore, it is possible to greatly reduce the work prior to the operator's CT imaging.

  The X-ray CT apparatus uses, when X-ray air calibration is performed, the shape and size of an object obtained by an optical camera and an image processing unit equivalent to those in each of the above-described inventions and position information with respect to the rotation axis of the rotary stage. It is. Air calibration is an indispensable procedure for accurately obtaining the X-ray luminance radiation distribution before CT imaging. In practice, the X-ray source tube voltage, tube current, X-ray source and X-ray detection are used. After determining the distance between the devices, remove the subject from the rotary stage and place it outside the field of view of the X-ray detector, irradiate the X-ray detector and integrate the output of the X-ray detector Thus, a reference image for determining the 100% level of each pixel is used. When the distance between the X-ray source and the X-ray detector is changed or the area size of the X-ray detector is changed (when a multi-image tube is used), it is necessary to perform this air calibration again. When the xy table is arranged on the movement of the rotation stage and / or the movement of the rotation stage by using the shape information, the size and the position information with respect to the rotation axis by the image processing using the appearance image of the object. Can be automatically moved out of the field of view of the X-ray detector.

  According to the present invention, it is possible to prevent the X-ray source and the subject from interfering (collision) without paying special attention to the operator, and to bring the subject as close to the X-ray source as possible. Thus, a high photographing magnification and a bright perspective image can be easily obtained.

  In addition, according to the X-ray CT apparatus, when the half scan is selected, the rotation direction that allows the subject to approach without interfering with the X-ray source when the subject rotates is determined. Even when obtaining a partial tomographic image of a plate-like object at the highest possible magnification, the operator can easily obtain a high magnification without paying attention to the direction of rotation of the rotary stage and the distance to the X-ray source. A tomographic image is obtained.

  According to the X-ray CT apparatus, since the CT imageable region determined by the positions of the X-ray source, the X-ray detector, and the rotary stage is displayed superimposed on the external appearance image of the subject, In addition to the ability to approach as close as possible without causing interference, it is possible to greatly reduce the work before CT imaging, and tomographic images of the intended area with the maximum magnification It is easy to obtain.

  Further, according to the X-ray CT apparatus, the subject is automatically detected at the time of air calibration using the shape and size of the subject obtained by image processing using the appearance image of the subject and the position information with respect to the rotation axis. Therefore, when the distance between the X-ray source and the X-ray detector is changed, the calibration work can be facilitated.

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 explanatory drawing of the calculation method of the diameter of the circle | round | yen C of CT imaging | photography possible area | region in the CT imaging area calculating part 16c in embodiment of this invention. It is explanatory drawing of the example of a display by the indicator 14 in embodiment of this invention. (A) is a top view which shows the example of the state which positioned the rotation stage 3 by the stage position setting part 16d of embodiment of this invention, (B) is by the stage position setting part 16d of embodiment of this invention. It is a side view which shows the example of the state which positioned the rotation stage. It is explanatory drawing of the example of a movement of the rotation stage 3 at the time of air calibration in embodiment of this invention. (A) is operation | movement explanatory drawing in the case of moving the xy table 5 in embodiment of this invention, It is a top view of the state before the movement of xy table 5, (B) is xy in embodiment of this invention. It is operation | movement explanatory drawing in the case of moving the table 5, It is a front view of the state before the movement of the xy table 5. FIG. (A) is operation | movement explanatory drawing at the time of moving the xy table 5 in embodiment of this invention similarly, It is a top view of the state after the movement of xy table 5, (B) is embodiment of this invention similarly FIG. 6 is an operation explanatory diagram when moving the xy table 5 in FIG. (A) is explanatory drawing of the method of restrict | limiting the rotation direction of the to-be-photographed object W at the time of half scan selection in embodiment of this invention, (B) is at the time of half scan selection in embodiment of this invention. FIG. 6 is an explanatory diagram of a method for limiting the direction of rotation of a subject W. FIG. 6 is a plan view of a principal part showing an example of a positioning state of a subject W when half scanning is selected in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray source 2 X-ray detector 3 Rotation stage 4 Stage moving mechanism 5 xy table 6 Optical camera 13 CT image reconstruction calculation apparatus 14 Display 15 Image data capture circuit 16 Calculation control apparatus 16a Image processing part 16b Image composition part 16c CT imaging region calculation unit 16d Stage position setting unit 16e Drive control unit L X-ray optical axis R Rotation axis W Subject

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 rotation stage 3 for rotating the subject W is disposed therebetween. The rotation stage 3 is rotated about a rotation axis R in the z-axis direction orthogonal to the x-axis direction along the X-ray optical axis L from the X-ray source 1 and is orthogonal to each other by the stage moving mechanism 4. It can move in the x, y and z axis directions. The rotary stage 3 and the stage moving mechanism 4 are driven and controlled by a drive signal supplied from the stage controller 11. An xy table 5 for mounting the subject W and moving it in the x and y axis directions is provided on the rotary stage 3, and this xy table 5 is driven by a drive signal supplied from the table controller 12. Drive controlled. Further, the X-ray detector 2 can move in the x-axis direction, and the position in the x-axis direction can be changed by a drive signal supplied from a detector position controller (not shown).

  At the time of CT imaging, the subject W is placed on the xy table 5 and irradiated with X-rays while being rotated about the rotation axis R, and the X-ray transmission data from the X-ray detector 2 is converted into CT for each minute rotation angle. The image reconstruction calculation device 13 takes it in. The CT image reconstruction calculation device 13 uses the X-ray transmission data of the subject W for 360 ° (180 ° + θ in the case of half scan described later) thus captured, and x− orthogonal to the rotation axis R. A tomographic image of the subject W sliced along a plane along the y plane is constructed and displayed on the display 14.

  Above the rotary stage 3 and the xy table 5, an optical camera 6 composed of a CCD, a lens and the like is disposed on the rotation axis R in a posture facing vertically downward. The optical camera 6 is coupled to the stage drive mechanism 4 by a column (not shown) or the like, and moves as the rotary stage 3 moves in the x, y, and z axis directions, and the rotary stage 3 always rotates. It is located on the axis R.

  The video signal from the optical camera 6, and hence the video signal of the rotating stage 3, the xy table 5 and the subject W placed thereon, is sent through the image data fetch circuit 15 to the image processing unit 16 a and It is taken into the image composition unit 16b.

  The image processing unit 16a obtains the shape and size of the subject W and the positional relationship with respect to the rotation axis R using the video signal from the optical camera 6. In addition, the image composition unit 16b synthesizes the appearance image of the subject W by the optical camera 6 and the CT imageable region obtained by the CT image region computation unit 16c described later, and displays them on the display unit 14. The arithmetic and control unit 16 is actually composed of a computer and its peripheral devices, and operates so as to realize the functions of the installed program. In FIG. FIG. 4 is a block diagram for each function of an installed program. In addition to the display device 14 and the image data capturing circuit 15, the arithmetic control device 16 is given a command for moving the rotary stage 3, the xy table 5, or the X-ray detector 2 by manual operation, and various other commands. An operation unit 17 is connected.

The CT imaging region calculation unit 16c performs geometric calculation using the position information of the rotary stage 3 and the X-ray detector 2 from the stage controller 11 and the detector position controller, and the effective width of the light receiving surface of the X-ray detector 2. Then, a circle representing the CT imaging possible area around the rotation axis R is calculated. That is, as shown in a plan view in FIG. 2, the distance in the x-axis direction between the X-ray source 1 (focal point, hereinafter the same) and the rotation axis R is A, and the light received by the X-ray source 1 and the X-ray detector 2 is the same. Assuming that the distance in the x-axis direction to the surface is B and the effective width in the y-axis direction of the light receiving surface of the X-ray detector 2 is D, the diameter Δ of the circle C representing the CT imaging possible region is
Δ = D × A / B (1)
Can be calculated. The circle C whose diameter Δ is calculated in this way is combined with the appearance image of the subject W by the image combining unit 16b and displayed on the display unit 14 as shown in the display example of the display unit 14 in FIG.

  The stage position setting unit 16d rotates the subject W around the rotation axis R by 360 ° using information on the shape and size of the subject W supplied from the image processing unit 16a and the positional relationship with the rotation axis R. Sometimes, the position of the rotary stage 3 where the circle drawn by the point on the subject W farthest from the rotation axis R and the X-ray source 1 are separated by a preset minute gap is obtained and rotated to that position. In order to automatically move the stage 3, a drive control signal is supplied to the stage controller 11 via the drive control unit 16e.

Next, the operation of the embodiment of the present invention will be described together with its usage.
First, the subject W is mounted on the xy table 5 with the rotary stage 3 and the xy table 5 positioned at a specified position, for example, the origin, the output of the optical camera 6 is captured, and the contour of the subject W is captured by the image processing unit 16a. Is extracted, and the positional relationship with respect to the shape, size, and rotation axis R is obtained.

  When CT imaging is instructed, the stage position setting unit 16d causes the subject W not to interfere with the X-ray source 1 and to approach the X-ray source 1 most when the subject W is rotated about the rotation axis R. In order to move the rotary stage 3 to a position, a drive signal is supplied to the rotary stage 3 via the drive controller 16e and the stage controller 11. The state after the movement is shown in a plan view in FIG. 4A and in a side view in FIG. As a result, the SOD is set to the minimum SOD that can obtain the X-ray fluoroscopic data of the brightest subject W with the highest magnification.

In this state, it is determined from the display on the display 14 whether or not the intended area is within the circle C representing the CT imaging possible area. If not, the X-ray detector 2 is set to x. Move in the axial direction to determine the SID. In determining the SID, after the operator changes the size of the circle C displayed on the display 14 to the circle C ′ by operating the operation unit 17, the circle C, which is an actual CT imaging possible region, is changed by the operator. The X-ray detector 2 can be automatically moved so as to coincide with the designated circle C ′.
In the above description, the X-ray detector 2 is moved in the x-axis direction for adjusting the region intended for imaging to the circle C. For this adjustment, the subject W is moved in the x-axis direction. It may be moved. For this purpose, the stage moving mechanism 4 may be driven manually or automatically to adjust the subject position.
That is, it can also be performed as follows. It is determined from the display on the display 14 whether or not the intended area is within the circle C representing the CT imaging possible area. If not, the stage moving mechanism 4 is driven to move the subject W over. Move in the x-axis direction to determine the SOD. In determining the SOD, after the operator changes the size of the circle C displayed on the display 14 to the circle C ′ by operating the operation unit 17, the circle C, which is an actual CT imaging possible region, is changed by the operator. The stage moving mechanism 4 may be driven to automatically move the subject W in the x-axis direction so as to coincide with the designated circle C ′.

  When the air calibration is instructed, the stage position setting unit 16d determines that the subject W is X based on information on the shape and size of the subject and the positional relationship with respect to the rotation axis R from the image processing unit 16a, as shown in FIG. A drive control unit 16e, a stage controller 11 and A drive signal is supplied to the rotary stage 3 and / or the xy table 5 via the table controller 12. In this state, air calibration is executed. After executing the air calibration, the rotary stage 3 and / or the xy table 5 are returned to the position before the air calibration.

  Next, after the operator moves the rotary stage 3 in the z-axis direction so that a desired slice surface is obtained, CT imaging is performed.

  Here, in the above description, the case where the xy table 5 is not moved (excluding air calibration) has been described. However, when the xy table 5 is moved, the rotary stage 3 is set to the following depending on the amount of movement. Change as shown. That is, for example, as shown in the plan view of FIG. 6A and the front view of FIG. 6B, the printed wiring board is the subject W and the IC chip Wa at the center in the y-axis direction is being observed. As for the distance between the X-ray source 1 and the rotation axis R, if the width of the subject W is B and the preset minute gap is δ, the stage position setting unit 16d is connected to the rotation axis R and the X-ray source 1. The rotary stage 3 is positioned so that the distance in the x-axis direction is (B / 2) + δ. From this state, when the xy table 5 is moved by a distance y in the y-axis direction as shown in the plan view of FIG. 7A and the front view of FIG. Since the distance to the farthest point is (B / 2) + y, the distance in the x-axis direction between the rotation axis R and the X-ray source 1 with the movement of the xy table 4 is (B / 2) + y + δ. Automatically changed to

  According to the embodiment of the present invention described above, the subject W can be brought as close to the X-ray source 1 as possible without interfering with the X-ray source 1 without confirmation by the operator before CT imaging. In addition, CT imaging can be performed under a high magnification, and even when imaging is performed at the same magnification, X-ray fluoroscopic data as bright as possible is obtained, and an image having a good SN can be obtained. Further, even when the xy table 5 is moved, an operation for confirming the interference of the subject W with the X-ray source 1 becomes unnecessary.

  Next, the operation when the half scan is selected will be described. The half scan can shorten the SOD when a plate-like subject W is enlarged and photographed at a position shifted from the center. However, it is necessary to pay attention to the direction of rotation of the subject W first. Stated. In the embodiment of the present invention, when the half scan is selected, based on the shape and size of the subject W from the image processing unit 16a and the position information with respect to the rotation axis R, FIGS. As shown in a plan view in FIG. 5B, the direction of rotation of the rotary stage 3 is limited to a direction in which the point farthest from the rotation axis R on the subject W is away from the X-ray source 1. Then, as shown in the plan view of FIG. 9, when the subject W is rotated by 180 ° + θ (θ is the X-ray spread angle), the subject W maintains a minute gap δ with respect to the X-ray source 1. The rotary stage 3 is positioned at a position where it can be performed.

  According to the operation at the time of half scanning in the above embodiment of the present invention, the operator does not pay attention to the direction of rotation of the subject W, and does not check the position of the rotary stage 3 by trial and error. An operator can select an optimal SOD by simply selecting a scan and perform CT imaging in the vicinity of each of a plurality of IC chips mounted on a printed wiring board as described above with a large magnification. Can be greatly reduced.

  As for the optical camera 6, as in the above-described embodiment, the subject W is always photographed while being positioned directly above or in the vicinity of the rotation axis R, and the optical camera 6 is fixed to an apparatus frame or the like. 3 is positioned at the origin position so that the rotation axis R is positioned directly below the optical camera 6, and an external appearance image of the subject W may be taken and stored in this state. The appearance image of the subject W to be displayed on the display unit 14 by combining with the circle C representing the CT imaging possible area obtained by the CT imaging area calculation unit 16c may be an image that has been previously captured and stored.

Further, in the above-described embodiment, the subject W does not interfere with the X-ray source 1 based on the shape and size of the subject W obtained by the image processing unit 16a and the positional information with respect to the rotation axis R, and is possible. Although the example in which the rotary stage 3 is positioned at a position as close as possible has been shown, when the rotary stage 3 is moved by manual operation, the rotary stage 3 is rotated at that position according to the position of the rotary stage 3 every moment. Automatically determine whether or not the subject W interferes with the X-ray source 1 and cause the subject W to interfere with the X-ray source 1 such as issuing an alarm or prohibiting rotation according to the determination result. You may comprise so that it may monitor.
This application is based on a Japanese patent application filed on November 12, 2004 (Japanese Patent Application No. 2004-328401), the contents of which are incorporated herein by reference.

Claims (10)

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 comprising a reconstruction calculation unit for reconstructing a tomographic image of the subject along a plane orthogonal to the rotation axis using the X-ray transmission data of the subject captured at predetermined angles. In
From the optical camera that captures the subject on the rotary stage from the rotational axis of the rotary stage or a position in the vicinity thereof, and the appearance image of the subject captured by the optical camera, the shape, size, and the shape of the subject An image processing unit that obtains information related to a position with respect to the rotation axis, and an interference monitoring unit that monitors interference between the subject and the X-ray source when the rotary stage is rotated using information obtained by the image processing unit ; The information about the positional relationship of the X-ray source, the X-ray detector and the rotary stage in the X-ray optical axis direction and the size of the light-receiving surface of the X-ray detector is used. A CT imaging region calculation unit for calculating a CT imaging possible region and a region calculated by the CT imaging region calculation unit are displayed superimposed on the subject image captured by the optical camera. X-ray CT apparatus characterized by a display unit for displaying on.   The interference monitoring unit determines whether or not the subject and the X-ray source interfere with each other when the rotary stage rotates based on the positions of the X-ray source and the rotary stage and information obtained by the image processing unit. The X-ray CT apparatus according to claim 1, wherein if there is interference, an alarm to that effect is issued.   The interference monitoring unit determines whether or not the subject and the X-ray source interfere with each other when the rotary stage rotates based on the positions of the X-ray source and the rotary stage and information obtained by the image processing unit. 3. The X-ray CT apparatus according to claim 1, wherein the rotation stage is prohibited when the interference occurs.   4. The X-ray CT apparatus according to claim 1, wherein when the half scan is selected, the interference monitoring unit changes the rotation direction of the rotary stage without causing the subject to interfere with the X-ray source. An X-ray CT apparatus characterized in that interference monitoring is performed by restricting the rotation stage to a direction in which the rotary stage can be more approached to an X-ray source. 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 comprising a reconstruction calculation unit for reconstructing a tomographic image of the subject along a plane orthogonal to the rotation axis using the X-ray transmission data of the subject captured at predetermined angles. In
From the optical camera that captures the subject on the rotary stage from the rotational axis of the rotary stage or a position in the vicinity thereof, and the appearance image of the subject captured by the optical camera, the shape, size, and the shape of the subject An image processing unit for obtaining information related to the position with respect to the rotation axis, and using the information obtained by the image processing unit, the rotation axis of the rotation stage is closest to the X-ray source and the rotation of the rotation stage is performed. A rotary stage position setting unit that sets a position of a rotary stage at which the subject does not interfere with the X-ray source, a positional relationship between the X-ray source, the X-ray detector, and the rotary stage in the X-ray optical axis direction; A CT imaging region calculation unit that calculates a CT imaging region centered on the rotation axis using information related to the size of the light receiving surface of the X-ray detector, and the CT The area calculated by the shadow region calculating unit, X-rays CT apparatus characterized by a display unit for displaying on the display device superimposed on the photographed object image by the optical camera.   6. The X-ray CT apparatus according to claim 5, wherein when the half scan is selected, the rotary stage position setting unit sets the rotation direction of the rotary stage so that the subject does not interfere with the X-ray source. The X-ray CT apparatus is characterized in that the position of the rotary stage is set by restricting the rotary stage to a more accessible direction. The control unit for moving the X-ray detector or the subject in the X-ray optical axis direction in conjunction with changing the size of the area displayed on the display unit. The X-ray CT apparatus according to 1, 2, 3, 4, 5 or 6. The X-ray detector according to claim 1, further comprising a subject retracting unit that moves the subject out of the field of view of the X-ray detector during X-ray air calibration using the information obtained by the image processing unit. Line CT device. X-ray CT in an X-ray CT apparatus having an X-ray source and an X-ray detector arranged opposite to each other, and a rotation stage that holds an object between them and rotates around a rotation axis orthogonal to the X-ray optical axis A method,
  Obtaining information regarding the shape, size, and position of the subject relative to the rotational axis from the appearance image of the subject taken by an optical camera disposed on or near the rotational axis of the rotational stage,
  Using the above information, monitor the interference between the subject and the X-ray source when the rotary stage rotates,
  The information about the positional relationship of the X-ray source, the X-ray detector, and the rotary stage in the X-ray optical axis direction and the size of the light receiving surface of the X-ray detector is used, and the rotation axis is the center. Whether or not a CT-capable region is calculated, and the calculated region is superimposed on the subject image captured by the optical camera and displayed on a display device, thereby obtaining a tomographic image of the intended region. After judging
  X-ray transmission data of the subject taken at predetermined angles while rotating the rotary stage is used to reconstruct a tomographic image of the subject along a plane orthogonal to the rotation axis. Line CT method. 10. The X-ray CT method according to claim 9, wherein the subject is moved out of the field of view of the X-ray detector during the X-ray air calibration using the information.