KR100888530B1 - X-ray ct system and x-ray ct method - Google Patents

Abstract

X-ray CT apparatus and X-ray CT method, in which the operator rotates the rotation stage before checking the CT scan to prevent interference with the X-ray source when the subject is rotated, and always allows the subject to approach the X-ray source as much as possible. To provide. The subject W placed on the rotating stage 3 is photographed by the optical camera 6, and image information using the data is used to determine the shape, size, and positional information on the rotation axis R of the subject W. Based on it, the interference between the subject W and the X-ray circle 1 is monitored or the rotation stage 3 is automatically positioned at the position closest to the X-ray circle without interference monitoring.

X-ray, CT device, rotating stage, subject

Description

X-ray CT system and X-ray CT method {X-RAY CT SYSTEM AND X-RAY CT METHOD}

The present invention relates to an industrial X-ray CT apparatus and an industrial X-ray CT method for obtaining a tomogram for nondestructively examining internal defects, internal structures, and the like of industrial products such as electronic components.

In industrial X-ray CT apparatus, a rotation stage is generally disposed between X-ray sources and X-ray detectors which are disposed opposite to each other, about an axis orthogonal to the X-ray optical axis. X-rays are irradiated onto the subject while holding the subject on the rotation stage. X-ray transmission data is obtained from an X-ray detector each time the rotating stage is rotated at a predetermined minute angle. The tomographic image of the subject along a plane perpendicular to the rotation axis of the rotation stage is reconstructed using the obtained X-ray transmission data (see Patent Document 1, for example). The rotating stage is typically moved by the moving mechanism in the X-ray optical axis (direction of the X axis) and in directions perpendicular thereto (directions of the Y axis and the Z axis). X-ray CT systems are known with an xy table on the rotation stage to move the subject in two directions perpendicular to the axis of rotation (directions of the x and y axes).

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-117024

[Problem to Invent]

By the way, in the industrial X-ray CT apparatus field as described above, for example, when obtaining a tomographic image such as in the vicinity of a semiconductor chip mounted on a circuit board, the subject wants to exceed the magnification as much as possible or is as bright as possible. It is necessary to bring the subject as close as possible to the X-ray source, for example, to obtain an image or the like. In the case of CT imaging, it is necessary to rotate the subject while placing the subject on the rotating stage, so that the operator can see the distance from the X-ray circle through the observation window while rotating the rotating stage while the subject is placed on the rotating stage before the actual CT imaging. Adjust the position of the rotating stage while checking. The rotating stage is placed as close as possible just before the position where the subject interferes with the X-ray circle. However, this has a problem that the work is complicated.

Furthermore, in an apparatus in which an xy table is provided on the rotating stage so that a desired position on the subject can be moved near the rotational center, after the xy table is moved, the adjustment is performed so that there is no interference with the X-ray source. It is necessary to confirm that this work is becoming a factor to reduce the work efficiency.

In addition, in the case of the so-called half-scan imaging in which the subject is rotated by about half the rotation intensity (actually corresponding to the sum of 180 degrees and the X-ray spread) and reconstructed by CT imaging, the subject can be approximated to the X-ray circle further. This is particularly effective when the observation site is moved from the center of the subject during the observation of the solder joint such as the IC package on the printed wiring. In this case, care must be taken in setting the rotation direction of the subject and the distance between the subject and the X-ray circle.

In addition, it is needless to say that X-ray transmission data of all points on the tomographic image is required in order to obtain the intended tomographic image, but based on the rotation stage with respect to the X-ray circle and the position of the X-ray detector in the X-ray optical axis direction Depending on the shooting magnification, the condition may not be satisfied. In the X-ray CT apparatus, the subject is placed on the rotating stage before the X-ray perspective image data of the subject is obtained, and rotated once while irradiating the X-ray to obtain the intended tomographic image from each X-ray perspective image. It is necessary to check whether the is located and change the location accordingly, which has become annoying.

The present invention is to solve the various problems in the conventional industrial X-ray CT device, the main problem is to prevent the interference to the X-ray source during the rotation of the subject, the operator before the CT imaging the rotation stage It is an object of the present invention to provide an X-ray CT device and an X-ray CT method that can make rotation work to be unnecessary.

In addition, another object of the present invention is to provide an X-ray CT apparatus in which the operator does not need to consider the rotation direction of the rotation stage in addition to the distance between the subject and the X-ray circle even when half scan is selected.

Another object of the present invention is to provide an X-ray CT apparatus capable of intuitively grasping whether an intended tomographic image can be obtained.

In order to solve the above-mentioned main problem, the X-ray CT apparatus of the present invention maintains a subject between the X-ray circle and the X-ray detector disposed opposite to each other and the rotating stage rotates about the rotation axis orthogonal to the X-ray optical axis. An X-ray having a reconstruction operation unit arranged to reconstruct a tomographic image of the subject along a plane orthogonal to the rotation axis by using the X-ray transmission data of the subject obtained at predetermined angles while rotating the rotation stage. In CT device,

An optical camera for photographing the subject on the rotation stage from a position on or near the rotation axis of the rotation stage;

An image processing unit for obtaining information on the shape, size, and position of the rotation axis of the subject from an external image of the subject photographed by the optical camera; And

And an interference monitoring unit for monitoring the interference between the subject and the X-ray source when the rotation stage is rotated using the information obtained by the image processing unit.

As a specific configuration of the interference monitoring unit of the present invention, based on the position of the X-ray circle and the rotation stage and the information obtained by the image processing unit, it is determined whether or not the subject and the X-ray source interfere with the rotation of the rotation stage. Discriminate, and in the case of interference, it is configured to give an alarm or similarly to determine whether or not the subject and the X-ray interfere with the rotation of the rotating stage, and if it interferes, prohibit the rotation of the rotating stage. The configuration can be adopted.

In addition, in the X-ray CT apparatus, when the half scan is selected, the interference monitoring unit approaches the rotation stage with respect to the X-ray source without causing the subject to interfere with the X-ray source in the direction of rotation of the rotation stage. It is also possible to employ a configuration in which interference monitoring is performed in a limited direction.

Further, in the present invention, the rotation axis of the rotation stage is closest to the X-ray circle and the rotation of the rotation stage is made using information obtained by the image processing unit in place of the interference monitoring unit claimed in claim 1. A configuration including a rotation stage positioning unit for setting the position of the rotation stage at which the subject does not interfere with the X-ray source may be employed.

Also in the X-ray CT apparatus having the rotation stage with the positioning unit, the rotation stage positioning unit at the time of the half scan is selected, the rotation stage of the rotation stage does not interfere with the X-ray circle, the subject does not interfere with the X-ray circle It is possible to adopt a configuration for setting the position of the rotation stage by restricting the rotation stage to a direction in which the rotation stage can be closer to each other, and when the half scan is selected with the X-ray CT apparatus, the operator rotates the subject. It is necessary to consider the direction and the like, and other problems of the present invention can be solved.

In the X-ray CT apparatus, the position of the X-ray circle, the X-ray detector and the rotation stage in the X-ray optical axis direction, and the size of the light-receiving surface of the X-ray detector are used as the center of the rotation axis. A CT photographing area calculator configured to calculate a CT photographable area; And

It is preferable to employ a structure including a display unit which superimposes the area calculated by the CT imaging area calculating unit on the subject photographed by the optical camera and displays it on the display.

Further, in the X-ray CT apparatus, the rotation axis is adjusted by using information about the positional relationship between the X-ray source, the X-ray detector and the X-ray optical axis direction of the rotation stage, and the size of the detector on the light receiving surface of the X-ray detector. A CT imaging area calculator which calculates an imageable area around the center;

A display unit for superimposing an area calculated by the CT imaging operation unit on a subject photographed by the optical camera and displaying the same on a display; And

It is also preferable to adopt a configuration including a control unit for moving the X-ray detector or the subject in the X-ray optical axis direction in conjunction with the case where the size of the area displayed on the display unit is changed.

In addition, the X-ray CT device of the present invention is an invention in which the main configuration requirements are the same as those of the X-ray CT device, and the rotation axis perpendicular to the X-ray optical axis by holding the subject between the X-ray sources and the X-ray detectors disposed opposite to each other The rotating stage which rotates around the center is arranged, and the cross-sectional image of the subject along the plane orthogonal to the rotation axis is obtained by using the X-ray transmission data of the subject obtained at every predetermined angle while rotating the rotating stage. In the X-ray CT device having a reconstruction operation unit for reconstructing,

An optical camera for photographing the subject on the rotation stage from a position on or near the rotation axis of the rotation stage;

An image processing unit for obtaining information on the shape, size, and position of the rotation axis of the subject from the appearance of the subject photographed by the optical camera; And

The object retreat part which moves the subject out of the field of view of an X-ray detector at the time of air correction of X-rays using the information obtained by the said image processing part is provided.

The present invention photographs a subject on a rotating stage by an optical camera on or near its axis of rotation, and obtains information on the shape, size, and position of the subject of rotation of the subject from the appearance of the subject; And

In the X-ray CT imaging apparatus, the main subject is solved by monitoring whether or not the subject interferes with the X-ray circle during rotation of the rotating stage, or by positioning the rotation stage where the subject approaches the X-ray circle without interference. I am trying to solve it.

In particular, by photographing the subject held on the rotating stage with an optical camera on or near the rotating axis, the shape, size, and positional information on the rotating axis of the rotating stage can be obtained. From this information, when rotation is applied to the subject at the position of the rotation stage (position of the rotation axis) at this time, it is possible to determine whether or not to interfere with the X-ray circle. In the X-ray CT apparatus, when it is determined that the interference is detected, an alarm is issued or monitoring such as prohibiting rotation of the rotating stage is performed.

In the X-ray CT apparatus, the rotation axis of the rotation stage is closest to the X-ray circle based on the same information, and the position where the subject does not interfere with the X-ray circle, that is, the imaging magnification and the brightness is maximized. Automatically locates at the location.

Such monitoring or positioning operation eliminates the necessity of checking for interference or repositioning prior to CT imaging.

In the X-ray CT apparatus, when the half scan is selected, the direction in which the subject is closer to the X-ray circle without interfering with the X-ray circle is determined from the appearance of the subject on the rotation stage, and the rotation direction of the rotation stage is determined. Direction and then perform monitoring or positioning of the rotary stage.

In addition, in the X-ray CT apparatus, CT imaging is performed by using the positional relationship between the X-ray circle, the X-ray circle detector, and the rotation axis of the rotation stage, in addition to the above setting function of the interference or the position of the rotation stage. Possible areas can be calculated by geometric calculations, and the calculated areas are superimposed and displayed on the exterior of the subject by the optical camera, thereby rotating the rotating stage while irradiating X-rays prior to CT imaging to check the instantaneous perspective view. Without doing this, it is possible to intuitively grasp whether the intended tomographic image can be obtained. By having both this function and the monitoring function of the interference with respect to the X-ray source of the subject or the rotation stage automatic positioning function, it is possible to greatly reduce the work prior to CT imaging of the operator. In addition, in the state where the rotation stage is as close to the X-ray source as possible by the function of the interference monitoring unit or the setting unit, it is possible to quickly determine whether a tomogram covering the intended area can be obtained. If this is impossible, it is possible to use a method such as moving the rotating stage away from the X-ray circle based on its closest position.

As described above, in the X-ray CT apparatus, the CT imageable area is calculated by geometric calculation by using the positional relationship between the X-ray circle X-ray detector and the rotation axis of the rotating stage as described above, and the calculated area is optically calculated. The display is superimposed on the appearance of the subject by the camera, or the X-ray detector or the subject is moved in the direction of the X-ray optical axis in conjunction with the case where the size of the displayed area is changed, that is, the region intended to be photographed is actually displayed. By controlling the X-ray detector or the X-ray subject so as to be within the CT imageable area of the camera, an operator can change the desired photographing region intuitively so that the subject does not interfere with the X-ray source at the time of imaging. Therefore, it is possible to significantly reduce work prior to CT imaging of the operator.

The X-ray CT system uses the shape, size, and positional information about the rotation axis of the rotating stage of the subject obtained by the optical camera and the image processing unit equivalent to those in the above-described inventions during the air calibration of the X-rays. Air calibration is an essential procedure to accurately determine the radiation distribution of the X-ray brightness before CT imaging, and in practice, after determining the tube voltage, tube current, distance between the X-ray source and the X-ray detector, etc. Is removed from the rotation stage and irradiated with the X-ray detector while the X-ray detector is located out of the field of view of the X-ray detector, and the output of the X-ray detector is integrated to form a reference image for determining the 100% level of each pixel. When the distance between the X-ray source and the X-ray detector is changed or when the area size of the X-ray detector is changed (using a multi-image tube), the air calibration needs to be performed once again. When the xy table is arranged on the movement of the rotation stage and / or by using the positional information on the shape, size and rotation axis of the subject by image processing using the appearance of the subject, the subject is moved by moving the xy table. It can automatically retract out of the field of view of the X-ray detector.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows the structural diagram of embodiment of this invention, and the block diagram which show a system structure are shown together.

FIG. 2: is explanatory drawing of the calculation method of the diameter of the circle | round | yen C of the area | region CT scanable in the CT imaging area | region calculation part 16c in embodiment of this invention.

3 is an explanatory diagram of a display example of the display device 4 in the embodiment of the present invention.

4A is a plan view showing an example of a state in which the rotary stage 3 is positioned by the stage positioning unit 16d of the embodiment of the present invention, and (B) is a stage of the embodiment of the present invention. It is a side view which shows the example of the state which positioned the rotation stage 3 by the positioning part 16d.

FIG. 5: 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.

FIG. 6A is a plan view of a state before the xy table 5 is moved in an operation explanatory diagram when the xy table 5 is moved in the embodiment of the present invention, and (B) is an embodiment of the present invention. In the form, it is an operation explanatory drawing in the case of moving the xy table 5, and is a front view of the state before the xy table 5 is moved.

FIG. 7A is an operation explanatory diagram when the xy table 5 is moved in the above embodiment of the present invention, and is a plan view of a state after the xy table 5 is moved, and FIG. In the above embodiment of the present invention, the operation explanatory diagram in the case of moving the xy table 5 is a front view of the state after the movement of the xy table 5.

8A is an explanatory diagram of a method of limiting the rotational direction of the subject W at the time of selecting the half scan in the embodiment of the present invention, and (B) the half scan in the embodiment of the present invention. It is explanatory drawing of the limitation method of the rotation direction of the subject W at the time of selection of.

Fig. 9A is a plan view of the principal parts of the embodiment of the present invention, showing an example of a positioning state of the subject W at the time of selecting the half scan.

Explanation of the sign

1 X-ray circle

2 X-ray detector

3 rotating stage

5 xy table

6 optical camera

13 CT image reconstruction unit

14 indicator

15 image data acquisition device

16 operation control device

16a image processing unit

16b image synthesizer

16c CT area calculation unit

16d stage positioning unit

16e drive control unit

L X-ray optical axis

R axis of rotation

W subject

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of one Embodiment of this invention, and is a figure which shows both the schematic diagram which shows a mechanical structure, and the block diagram which shows a system structure.

 An X-ray detector 2 is disposed facing the X-ray circle 1, and a rotation stage 3 for imparting rotation to the object W is disposed between them. The rotation stage 3 is provided with rotation about the rotation axis R in the z-axis direction orthogonal to the x axis direction aligned with the X-ray optical axis L from the X-ray circle 1, and the stage moves at the same time. The mechanism 4 is able to move in the mutually orthogonal x, y, and z axis directions. The rotary stage 3 and the stage moving mechanism 4 are drive controlled by a drive signal supplied from the stage controller 11. In addition, an xy table is mounted on the rotating stage 3 to mount the subject W to move in the x and y axis directions. The xy table 5 is driven by a drive signal supplied from the table controller 12. Drive controlled. In addition, the X-ray detector 2 is movable 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).

In the case of CT imaging, the subject W is placed on the xy table 5 and irradiated with X-rays to impart rotation about the rotation axis R, and the X from the X-ray detector 2 for every minute rotation angle. The line transmission data is obtained by the CT image reconstruction arithmetic unit 13. In the CT image reconstruction calculator 13, the plane along the xy plane orthogonal to the rotation axis R is obtained by using X-ray transmission data belonging to 360 degrees (180 degrees + θ in the case of half scan described later) obtained in this way. A tomographic image of the object W sliced at is constructed and displayed on the display unit 14.

Above the rotation stage 3 and the xy table 5, the optical camera 6 which becomes a CCD, a lens, etc. on the rotation axis R is arrange | positioned in the vertical downward direction. The optical camera 6 is coupled to the stage drive mechanism 4 by a column (not shown) or the like, moves in association with the movement in the x, y and z axis directions of the rotation stage 3, and the rotation stage 3. It is located on the rotating shaft R of ().

The image signal from the optical camera 6, i.e., the image signal of the rotating stage 3, the xy table 5 and the subject W positioned thereon, is passed through the image data acquisition circuit 15 of the operation control device 16. It is obtained by the image processing unit 16a and the image combining unit 16b.

The image processing unit 16a uses the video signal from the optical camera 6 to determine the shape, size, and positional relationship of the rotation axis R of the subject W. FIG. In addition, the image synthesizing unit 16b synthesizes the visual appearance of the subject W by the optical camera 6 and the CT imageable area obtained by the CT imaging area calculating unit 16c described later and displays them on the display 14. . In practice, the arithmetic and control unit 16 is composed of a computer and its peripherals, and operates to realize a function having a program installed. However, in FIG. 1, it is shown in the form of the block diagram for every function which has the program installed for the convenience of description. In addition to the display 14 and the image data acquisition circuit 15, the arithmetic and control device 16 includes instructions for moving the rotation stage 3, the xy table 5, or the X-ray detector 2 by manual operation. The operation unit 17 for giving other various commands is connected.

The CT imaging area calculating unit 16c uses geometry of the rotation stage 3 and the position information of the X-ray detector 2 and the effective width of the light receiving surface of the X-ray detector 2 from the stage controller 11 and the detector position controller. By calculation, a circle representing a CT imageable area around the rotation axis R is calculated. In particular, as shown in plan view in FIG. 2, the distance between the X-ray circle 1 (hereinafter referred to as focus) and the rotation axis R in the x-axis direction is A, the X-ray circle 1 and the X-ray detector. If the distance in the x-axis direction with respect to the light-receiving surface of (2) 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 of the circle C representing the CT imaging possible region Δ is

Δ = D × A / B ... (1)

It can be calculated as The circle C in which the diameter Δ is calculated in this way is synthesized with the appearance of the subject W by the image synthesizing portion 16b as in the case where the display example of the display 14 is shown in FIG. 3. Is displayed.

The stage positioning unit 16d uses the information about the shape, size, and positional relationship of the rotation axis R of the subject W supplied from the image processing unit 16a to move the subject W around the rotation axis R. FIG. In the case of 360 degree rotation, the position where the circle drawn by the point on the subject W, which is farthest from the rotation axis R, and the X-ray circle 1 are separated by a predetermined minute interval is obtained. The drive control signal is supplied to the stage controller 11 via the drive control unit 16e to automatically move the rotation stage 3 to the position.

Next, the operation of the embodiment of the present invention will be described together with the usage thereof.

First, the subject W is mounted on the xy table 5 with the rotation stage 3 and the xy table 5 positioned at a prescribed position, for example, the origin, and the output of the optical camera 6 is obtained. The outline of the subject W is extracted by the image processing unit 16a, and the shape, size, and positional relationship with respect to the rotation axis R are obtained.

When the CT imaging is commanded, the stage position setting unit 16d rotates the subject W around the rotation axis R, whereby the subject W does not interfere with the X-ray circle, and furthermore, the most X-ray circle 1 The drive signal is supplied to the rotation stage 3 via the drive control unit 16e and the stage controller 11 to move the rotation stage 3 to a position close to. The state after the movement is shown in a plan view in Fig. 4A and a side view in Fig. 4B. This sets the minimum SOD at which the magnification is highest and the X-ray perspective data of the brightest subject W can be obtained.

In this state, it is determined from the display of the indicator 14 whether or not the intended area is accommodated in the circle C representing the CT imageable area without excess or insufficient, and if it is negative, the X-ray detector 2 is moved in the x-axis direction. To determine the SID. After the operator changes the size of the circle C displayed on the indicator 14 in connection with the determination of this SID to the circle C 'by the operation of the operation unit 17, the circle which is the actual CT photographable area. The X-ray detector 2 may be automatically moved so that (C) coincides with the designated circle C 'of the operator.

In the above description, the X-ray detector 2 is moved in the x-axis direction for the adjustment for fitting the area to be photographed to the circle C, but for this adjustment, the subject W may be moved in the x-axis direction. good.

In particular, you can also: From the display of the indicator 14, it is judged whether or not the intended area is accommodated in the circle C representing the CT imageable area without oversufficiency. If it is negative, the stage moving mechanism 4 is driven to drive the subject W. Determine the SOD by moving in the x-axis direction. In the determination of this SOD, after the operator changes the size of the circle C displayed on the indicator 14 to the circle C 'by the operation of the operation unit 17, the circle (the actual CT photographable area) ( The stage moving mechanism 4 may be driven so that C) coincides with the designated circle C 'of the operator so as to automatically move the subject W in the x-axis direction.

When the air correction is commanded, the stage position setting unit 16d displays the subject as shown in FIG. 5 based on the information on the shape, size, and positional relationship to the rotation axis R of the subject from the image processing unit 16a. The drive control unit may automatically move the rotation stage 3 and / or the xy stage 5 in the y-axis direction or in addition to the x-axis direction so that (W) is out of view of the X-ray detector 2. 16e), the drive signal is supplied to the rotation stage 3 and / or the xy table 5 via the stage controller 11 and / or the table controller 12. In this state, air calibration is performed. After the execution of this air calibration, the rotary stage 3 and / or the xy table 5 are returned to the position before air calibration.

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

In the above description, the case where the xy table 5 is not moved (except for the air calibration) has been described. When the xy table 5 is moved, the rotation stage 3 will be described below corresponding to the movement amount. Change to display. In particular, for example, as shown in a plan view in Fig. 6A and a front view in Fig. 6B, the IC chip Wa in the center portion of the y-axis direction is observed using the printed wiring board as the object W. In the state, when the distance between the X-ray circle 1 and the rotation axis R is the width of the subject W as B, and the predetermined minute interval is δ, the stage positioning unit 16d is the rotation axis R. ) And the rotation stage 3 are positioned so that the distance between the X-ray circle 1 and the X-ray circle 1 becomes (B / 2) + δ. As shown in the plan view in FIG. 7A and the front view in FIG. 7B, when the xy table 5 is moved by the distance y in the axial direction, it is most spaced apart from the rotation axis R on the subject W. FIG. Since the distance to the existing point becomes (B / 2) + y, the distance in the x axis direction between the rotation axis R and the X-ray circle 1 is (B / 2) with the movement of the xy table 4. It is automatically changed to + y + δ.

According to the embodiment of the present invention, the subject W does not interfere with the X-ray source without the operator confirming before CT imaging, and the subject W can be brought closer to the X-ray source 1 as much as possible. In addition, CT imaging can be performed on the basis of a high magnification, and even when imaging is performed at the same magnification, bright X-ray perspective data can be obtained as much as possible, thereby obtaining an image having a good SN. In addition, when the xy table 5 is moved, the operation for confirming the interference of the subject W with respect to the X-ray circle 1 becomes unnecessary.

Next, an operation when half scan is selected will be described. The half scan can shorten the SOD even more in the case of enlarging the position of the plate-like subject off the center thereof, but the need for attention in the direction of rotation of the subject W has been described above. In the embodiment of the present invention, when half scan is selected, Figs. 8A and 8B are based on the shape, size, and positional information of the rotation axis R of the subject W from the image processing unit 16a. As shown in plan views, respectively, the point where the rotation direction of the rotation stage 3 is located farthest from the rotation axis R on the subject W is limited to the direction away from the X-ray circle 1. In addition, as shown in the plan view in FIG. 9, when the subject W is rotated by 180 degrees + θ (θ is the diffusion angle of the X-ray circle), the subject W is the X-ray circle 1. The rotation stage 3 is positioned at a position capable of maintaining a small interval δ with respect to).

 According to the operation at the time of half scan in the above embodiment of the present invention, the operator does not need to pay attention to the direction of rotation of the subject W, and does not confirm the position of the rotation stage 3 by trial and error. The optimum SOD is set only by selecting the half scan, and the burden on the operator is greatly reduced in the case of CT imaging of the vicinity of a plurality of IC chips mounted on the printed wiring board as described above based on a large magnification. I can alleviate it.

In addition, the optical camera is always positioned directly above or near the rotation axis R as in the above-described embodiment, to photograph the subject W, and to fix the optical camera 6 to an apparatus frame or the like, for example, by rotating the stage ( 3) by positioning it to the origin position, the rotation axis R may be positioned directly under the optical camera 6, and the image of the external appearance of the subject W may be photographed and stored in this state. The appearance of the subject W may be an image captured in advance and stored so as to be combined with a circle C representing the CT imageable area obtained by 16c) and displayed on the display 14.

In the above-described embodiment, the subject W does not interfere with the X-ray circle 1 based on the shape, size, and positional information on the rotation axis R of the subject W obtained by the image processing unit 16a. In addition, although the example which positions the rotation stage 3 in the approaching position as possible is shown, when the rotation stage 3 is moved by manual operation, it respond | corresponds to the position of the rotation stage 3 at the moment. In the case where the rotating stage 3 is rotated at the position, it is automatically determined whether the subject W interferes with the X-ray circle 1, and whether or not an alarm is issued or rotated automatically based on the determination result. And the interference monitoring of the X-ray source 1 of the subject W, such as an alarm or a prohibition of rotation, may be performed according to the determination result.

Since this application is based on the JP Patent application (patent application 2004-328401) of an application on November 12, 2004, the content is taken in here as a reference.

According to the present invention, it is possible to prevent the operator from interfering (collision) between the X-ray source and the subject without paying particular attention, and to bring the subject as close to the X-ray source as possible, and to have a high shooting magnification or bright perspective image. Can be easily obtained.

Further, according to the X-ray CT apparatus, since the rotation direction in which the subject can be brought close to each other is determined by not interfering with the X-ray circle when the subject rotates when the half scan is selected, in particular, the subject of the subject on the plate such as a printed wiring board is determined. Even when the partial tomographic image is obtained at a magnification as high as possible, an easy and high magnification tomographic image can be obtained without the operator paying attention to the rotation direction of the rotating stage or the distance from the X-ray circle.

According to the X-ray CT apparatus, the CT imageable area determined by the positions of the X-ray circle, the X-ray detector, and the rotating stage is superimposed on the external appearance of the subject, so that the subject is approached as little as possible without interfering with the X-ray source. It is possible to significantly reduce the work before CT imaging by having a function to make it possible, and it is easy to obtain the tomographic image of the intended area at the maximum magnification.

Further, according to the X-ray CT apparatus, the subject is automatically moved out of the field of view of the X-ray detector at the time of air correction by using the positional information on the shape size and the rotation axis of the subject, which is also obtained by image processing to facilitate the appearance of the subject. Therefore, the correction work can be facilitated in the case where the distance between the X-ray source and the X-ray detector is changed.

Claims (13)

A rotation stage is disposed between the X-ray sources and the X-ray detectors arranged opposite to each other and rotated about a rotation axis orthogonal to the X-ray optical axis, and is obtained at predetermined angles while rotating the rotation stage. An X-ray CT apparatus having a reconstruction operation unit for reconstructing a tomographic image of the subject along a plane orthogonal to the rotation axis using X-ray transmission data of the subject, An optical camera for photographing the subject on the rotation stage from a position on or near the rotation axis of the rotation stage; An image processing unit for obtaining information on the shape, size, and position of the rotation axis of the subject from an external image of the subject photographed by the optical camera; An interference monitoring unit for monitoring the interference between the subject and the X-ray source when the rotation stage is rotated using the information obtained by the image processing unit; Computing a CT imageable area around the rotation axis using information on the positional relationship between the X-ray source, the X-ray detector and the rotation stage in the X-ray optical axis direction, and the size of the light receiving surface of the X-ray detector. CT imaging area calculator; And And a display unit for superimposing an area calculated by the CT photographing area calculating unit on a subject photographed by the optical camera and displaying the same on a display. The method of claim 1, The interference monitoring unit determines whether or not the subject and the X-ray source interfere when the rotation stage rotates based on the position of the X-ray source and the rotation stage and the information obtained by the image processing unit. X-ray CT device that emits an alarm to that effect. The method of claim 1, The interference monitoring unit determines whether or not the subject and the X-ray source interfere with the rotation stage when the rotation stage is rotated based on the position of the X-ray source and the rotation stage and the information obtained by the image processing unit. X-ray CT apparatus for prohibiting the rotation of the rotating stage. The method of claim 1, When the half scan is selected, the interference monitoring unit performs X-ray monitoring by limiting the rotation direction of the rotation stage to a direction in which the subject does not interfere with the X-ray source, but closer to the X-ray source toward the rotation stage. CT device. A rotation stage disposed between the mutually disposed X-ray sources and X-ray detectors and rotating around a rotation axis orthogonal to the X-ray optical axis while maintaining the subject; A reconstruction calculator configured to reconstruct a tomographic image of the subject along a plane orthogonal to the rotation axis by using the X-ray transmission data of the subject obtained at predetermined angles while rotating the rotation stage; An optical camera for photographing the subject on the rotation stage from a position on or near the rotation axis of the rotation stage; An image processing unit for obtaining information on the shape, size, and position of the rotation axis of the subject from the appearance of the subject photographed by the optical camera; And Using the information obtained by the image processing unit to set the position of the rotation stage where the rotation axis of the rotation stage is closest to the X-ray source and the subject does not interfere with the X-ray source when the rotation stage is rotated. A rotation stage position setting unit; Computing a CT imageable area around the rotation axis using information on the positional relationship between the X-ray source, the X-ray detector and the rotation stage in the X-ray optical axis direction, and the size of the light receiving surface of the X-ray detector. CT imaging area calculator; And And a display unit for superimposing an area calculated by the CT photographing area calculating unit on a subject photographed by the optical camera and displaying the same on a display. The method of claim 5, wherein When the half scan is selected, the rotation stage positioning unit limits the rotation direction of the rotation stage to a direction in which the subject can bring the rotation stage closer to the X-ray circle without interfering with the X-ray circle. X-ray CT device to set the position of the rotating stage. delete The method according to claim 1 or 5, And a control unit which moves the X-ray detector or the subject in the X-ray optical axis direction in association with the change of the size of the area displayed on the display unit. A rotation stage including an X-ray source and an X-ray detector disposed opposite to each other, the rotation stage being arranged to rotate about a rotation axis perpendicular to the X-ray optical axis while holding the subject between the X-ray source and the X-ray detector; A reconstruction calculator configured to reconstruct a cross-sectional view of the subject along a plane orthogonal to the rotation axis by using the X-ray transmission data of the subject obtained at predetermined angles while rotating the rotation stage; An optical camera for photographing the subject on the rotation stage from a position on or near the rotation axis of the rotation stage; An image processing unit for obtaining information on the shape, size, and position of the rotation axis of the subject from the appearance of the subject photographed by the optical camera; A subject evacuation unit which moves the subject out of the field of view of the X-ray detector during air calibration of the X-rays using the information obtained by the image processing unit; Computing a CT imageable area around the rotation axis using information on the positional relationship between the X-ray source, the X-ray detector and the rotation stage in the X-ray optical axis direction, and the size of the light receiving surface of the X-ray detector. CT imaging area calculator; And And a display unit for superimposing an area calculated by the CT photographing area calculating unit on a subject photographed by the optical camera and displaying the same on a display. A rotation stage including an X-ray circle and an X-ray detector disposed opposite to each other, the rotation stage being arranged to rotate about a rotation axis orthogonal to the X-ray optical axis while holding the subject between the X-ray source and the X-ray detector. In the X-ray CT method of the X-ray CT apparatus to Obtaining information about a shape, a size, and a position with respect to a rotation axis of the subject from an appearance of the subject photographed by an optical camera disposed at a position along the rotation axis of the rotation stage or at a position close to the rotation axis; Calculating a CT imageable area around the rotation axis using the information; Displaying an image in which the calculated region and the appearance overlap; Monitoring the interference between the subject and the X-ray circle when the rotation stage is rotated using the information; And X-ray CT method of the X-ray CT apparatus comprising the step of reconstructing the tomographic image of the subject along a plane orthogonal to the axis of rotation using the X-ray perspective data of the subject obtained at a predetermined angle when the rotation stage is rotated . The method of claim 10, And moving the subject out of the field of view of the X-ray detector when performing X-ray adjustment using the information. The method of claim 9, And a control unit for moving the X-ray detector or the subject in the direction of the X-ray optical axis in association with the change of the size of the area displayed on the display unit. The method of claim 10, Moving the X-ray detector or the subject in the direction of the X-ray optical axis in association with the change of the size of the displayed area.

Images