X-ray CT device

Abstract

The present invention provides an X-ray CT apparatus capable of acquiring a high-quality X-ray CT image by suppressing generation of artifacts. This X-ray CT apparatus is provided with: an X-ray photographing system provided with an X-ray application unit 11 and an X-ray detector 12; a rotary stage 13 disposed between the X-ray application unit 11 and the X-ray detector 12; a rotation mechanism for relatively rotating the X-ray photographing system and the rotary stage 13 about a rotary axis orthogonal to the optical axis of X-rays reaching the X-ray detector 12 from the X-ray application unit 11; and a load mechanism 50 installed on a stage 14 so as to apply a testing force to a test piece, the X-ray CT apparatus further being provided with an angle changing mechanism 30 for tilting the bending tester 50 to thereby displace the direction, in which the bending tester 50 applies the testing force to the test piece, from the direction orthogonal to the optical axis of X-rays.

Description

[Technical field]

[0001] The present invention relates to an X-ray CT apparatus. [Background technology]

[0002] In material testing, in which a test force is applied to a test piece to clarify characteristics such as the strength of the material, X-ray CT imaging may be performed on the test piece to which the test force is applied in order to observe the state of internal destruction of the test piece. An industrial X-ray CT device includes an X-ray irradiation unit, an X-ray detector arranged opposite to the X-ray irradiation unit, and a stage that rotates with the test piece placed between the X-ray irradiation unit and the X-ray detector, and is configured to observe the three-dimensional internal structure of the test piece by performing X-ray fluoroscopy while rotating the stage. In addition, a CT imaging device that performs X-ray CT imaging while a test force is applied to the test piece is also used (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4059197 Summary of the Invention [Problem to be solved by the invention]

[0004] FIG. 10 is a schematic diagram showing how a bending test is performed on a printed circuit board as a test piece in a CT imaging apparatus that performs X-ray CT imaging while a test force is applied to the test piece.

[0005] This printed circuit board has a structure in which a substrate 102 and an electronic component 101 are joined by solder joints 103. The printed circuit board rotates about a rotation axis 100 facing in the vertical direction, and a test force is applied downward as shown by arrow 107, so that bending stress is applied to the printed circuit board as a test piece. In this state, X-rays irradiated from an X-ray irradiator 104 and transmitted through the printed circuit board are detected by an X-ray detector 105, whereby X-ray CT imaging of the printed circuit board is performed.

[0006] When X-ray CT imaging is performed with this configuration, the multiple solder joints 103 in the observation target area rotate within the same plane, and metal artifacts originating from the solder joints 103 occur in the image captured by the X-ray detector 105. When such artifacts occur significantly, it becomes difficult to accurately observe the observation target area including the solder joints 103.

[0007] This phenomenon is not limited to when a printed circuit board is used as the test specimen, but can also occur when X-ray CT imaging is performed using CFRP (carbon fiber reinforced plastic) or GFRP (glass fiber reinforced plastic) as the test specimen, and the distance that the X-rays pass through the test specimen becomes large.

[0008] The present invention has been made to solve the above-mentioned problems, and has an object to provide an X-ray CT apparatus capable of suppressing the occurrence of artifacts and obtaining high-quality X-ray CT images. [Means for solving the problem]

[0009] A first aspect of the present invention is an X-ray CT device comprising an X-ray imaging system having an X-ray irradiation unit and an X-ray detector, a stage arranged between the X-ray irradiation unit and the X-ray detector, a rotation mechanism for relatively rotating the X-ray imaging system and the stage around a rotation axis perpendicular to the optical axis of the X-rays extending from the X-ray irradiation unit to the X-ray detector, and a loading mechanism installed on the stage for loading a test force onto a test piece, the device further comprising an angle changing mechanism for tilting the loading mechanism to displace the direction in which the loading mechanism applies the test force to the test piece from a direction perpendicular to the optical axis of the X-rays. Effect of the Invention

[0010] According to the first aspect of the present invention, by tilting the loading mechanism and displacing the direction in which the loading mechanism applies a test force to the test piece from a direction perpendicular to the optical axis of the X-rays, it is possible to suppress the occurrence of artifacts and obtain high-quality X-ray CT images. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of an X-ray CT apparatus according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing a main control system of an X-ray CT apparatus according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a front view of the bending test machine 50. [Figure 4] FIG. 2 is a perspective view of a bending test machine 50. [Diagram 5] FIG. 2 is a front view of the angle changing mechanism 30. [Figure 6] FIG. 2 is a side view of the angle changing mechanism 30. [Figure 7] FIG. 2 is a perspective view of the angle changing mechanism 30. [Figure 8] 1 is a schematic diagram showing how X-ray CT imaging is performed while a test force is applied to a test piece TP. FIG. [Figure 9] 1 is a schematic diagram showing how X-ray CT imaging is performed while a test force is applied to a test piece TP. FIG. [Figure 10]FIG. 1 is a schematic diagram showing a state in which a bending test is performed on a printed circuit board as a test piece. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram of an X-ray CT apparatus according to an embodiment of the present invention. Fig. 2 is a block diagram showing a main control system of the X-ray CT apparatus according to the embodiment of the present invention.

[0013] This X-ray CT apparatus includes an X-ray irradiation unit 11, an X-ray detector 12, and a rotating stage 13. This X-ray CT apparatus has a bending tester 50 as a loading mechanism according to the present invention installed on the rotating stage 13 arranged between the X-ray irradiation unit 11 and the X-ray detector 12 arranged opposite to each other, and rotates together with the bending tester 50 to perform X-ray CT imaging of the test piece TP to which a load is applied by the bending tester 50, thereby performing non-destructive internal observation. The bending tester 50 is placed on the rotating stage 13 via an angle changing mechanism 30, which will be described later.

[0014] The X-ray irradiation unit 11 includes an X-ray tube as an X-ray source, and generates X-rays from the X-ray tube according to a tube voltage and a tube current supplied from a high voltage generator 15. The high voltage generator 15 is controlled by an X-ray control unit 16, which is connected to a personal computer 20 in which control software for controlling the entire X-ray CT apparatus is installed. The X-ray detector 12 is an image intensifier (II) combined with a CCD camera or an FPD (Flat Panel Detector), and is connected to the personal computer 20 via a CT image reconstruction calculation unit 18. In order to enlarge or reduce the fluoroscopic imaging area, the X-ray detector 12 is configured to be movable toward or away from the rotating stage 13, and the rotating stage 13 is also configured to be movable toward or away from the X-ray irradiation unit 11.

[0015] The rotating stage 13 is capable of moving in a horizontal direction parallel to the optical axis of the X-rays extending from the X-ray irradiation unit 11 to the X-ray detector 12, and in a vertical direction perpendicular to the optical axis of the X-rays. The stage driving mechanism 14 is connected to a personal computer 20 via a stage control unit 17.

[0016] When performing X-ray CT imaging under bending test, a test piece is attached to a bending tester 50 installed on a rotating stage 13 and a bending load is applied. In addition, X-rays are irradiated from the X-ray irradiation unit 11 toward the test piece. Then, the rotating stage 13 is rotated about a rotation axis 100 perpendicular to the optical axis of the X-rays from the X-ray irradiation unit 11 to the X-ray detector 12. In this state, the X-rays transmitted from all directions over 360 degrees around the test piece are detected by the X-ray detector 12, and the X-ray transmission data is input to the CT image reconstruction calculation unit 18.

[0017] The CT image reconstruction calculation unit 18 is composed of a computer including a ROM, RAM, hard disk, etc. as storage devices for storing programs and detection data of the X-ray detector 12, and a CPU as a calculation device. The CT image reconstruction calculation unit 18 uses the captured X-ray transmission data of the test piece for 360 degrees to construct tomographic images (CT images) of the test piece sliced ​​in multiple planes. The CT images are transmitted from the CT image reconstruction calculation unit 18 to a personal computer 20 and used for three-dimensional imaging by a three-dimensional image construction program installed in the personal computer 20.

[0018] A display unit 23 such as a liquid crystal display and an operation unit 22 equipped with a keyboard and a mouse are connected to the personal computer 20. The display unit 23 displays the CT images transmitted from the CT image reconstruction calculation unit 18 to the personal computer 20, and also displays a three-dimensional image constructed using the CT images. The functions of the CT image reconstruction calculation unit 18 may be integrated with the personal computer 20 and realized by a single computer as a computer peripheral device or software.

[0019] Next, the configuration of a bending tester 50 as a loading mechanism according to the present invention will be described. Fig. 3 is a front view of the bending tester 50, and Fig. 4 is a perspective view of the bending tester 50. Note that in Fig. 4, the camera 81 and the connecting members 82 and 83 are omitted from the illustration.

[0020] This bending tester 50 performs a three-point bending test on a test piece TP using an indenter 52 and a pair of fulcrums 51. In this embodiment, the test piece TP is a printed circuit board, and has a configuration in which a board 1 and an electronic component 2 are joined by solder joints 3.

[0021] This bending test machine 50 includes a base plate 57, three support columns 58 erected at equal intervals on this base plate 57, a head plate 53 and a pair of fixed plates 55, 56 fixed to the support columns 58 at a predetermined interval, and a moving plate 54 having a through hole penetrating the support columns 58 and movable along the support columns 58. The base plate 57, the head plate 53 and the pair of fixed plates 55, 56 are connected to a pair of support members 31 described later.

[0022] Between the pair of fixed plates 55, 56, a gear 63 is disposed which can rotate between spacers disposed on each of the fixed plates 55, 56. Inside the gear 63, a nut is disposed which screws with a threaded rod 64. The threaded rod 64 is connected to the moving plate 54, and an indenter 52 is disposed at the tip of the threaded rod 64. A motor 61 is disposed on the lower surface of the fixed plate 55. A spur gear 62 which meshes with the gear 63 is disposed on the rotating shaft of the motor 61. When the spur gear 62 and the gear 63 are rotated by the drive of the motor 61, the threaded rod 64 which screws with a nut in the gear 63 moves up and down. As the threaded rod 64 moves up and down, the moving plate 54 and the indenter 52 move up and down. A pair of fulcrums 51 are disposed on the lower surface of the head plate 53. The test piece TP is held between the pair of fulcrums 51 and the indenter 52, and a test force is applied from the indenter 52 as the indenter 52 moves up and down.

[0023] A connection member 83 is attached to the side of the base plate 57, and a connection member 82 supporting a camera 81 is fixed to the connection member 83. The camera 81 is for photographing a test piece TP on which a bending test and X-ray CT imaging are performed.

[0024] The support 58 is required to be made of a material with high rigidity in order to prevent deformation of the bending test machine 50 even when a test force is applied to the test piece TP. On the other hand, in order to prevent artifacts, the support 58 is required to be made of a material with high X-ray transmittance. In order to satisfy these conditions, aluminum or CFRP can be used for the support 58. The pair of supports 51 and the indenter 52 are also made of CFRP or the like in order to prevent artifacts.

[0025] In this bending tester 50, the driving mechanisms such as the motor 61 and gears 63, which have a relatively large weight, are disposed downward to lower the center of gravity of the entire device, thereby enabling the device to be stably installed on the rotating stage 13.

[0026] Next, the configuration of the angle change mechanism 30 will be described, which changes the angle between the loading direction of the test force on the test piece TP and the optical axis of the X-rays extending from the X-ray irradiation unit 11 to the X-ray detector 12 by changing the inclination angle of the bending test machine 50 as a loading mechanism. FIG. 5 is a front view of the angle change mechanism 30. FIG. 6 is a side view of the angle change mechanism 30. FIG. 7 is a perspective view of the angle change mechanism 30. In these figures, the bending test machine 50 is shown typically by virtual lines. In FIG. 7, the support shaft 34, the bolt 35, the nut 36, and the hole 39 are omitted from illustration.

[0027] A pair of support members 31, which are connected to the base plate 57, the head plate 53, and the pair of fixed plates 55, 56 and support the bending tester 50, are connected to a pair of stand members 33 erected on a base 32 via a support shaft 34, and the bending tester 50 swings around the support shaft 34 together with the pair of support members 31. An arc-shaped hole 39 is formed in each stand member 33. A bolt 35 penetrating the hole 39 is disposed in each support member 31, and a nut 36 and a nut 37 are disposed on both ends of the bolt 35. When the nut 36 is loosened, the bending tester 50 can swing around the support shaft 34, and when the nut 36 is tightened, the swinging motion of the bending tester 50 is restricted. The inclination angle of the bending tester 50 can be changed by the action of this angle change mechanism 30, and thus it is possible to change the angle between the direction of the test force applied to the test piece TP by the bending tester 50 and the optical axis of the X-ray.

[0028] Next, in the X-ray CT imaging device having the above configuration, an operation will be described when X-ray CT imaging is performed while applying a test force to the test piece TP by the bending test machine 50. Figures 8 and 9 are schematic diagrams showing how X-ray CT imaging is performed while a test force is applied to the test piece TP.

[0029] When performing X-ray CT imaging while applying a test force to the test piece TP by the bending tester 50, the test piece TP is clamped between a pair of supports 51 and an indenter 52 as shown in Figs. 8 and 9. Then, the motor 61 shown in Figs. 3 and 4 is driven to move the indenter 52 in the direction of the pair of supports 51, thereby applying a bending test force to the test piece TP. Then, in this state, the rotation stage 13 is rotated to rotate the bending tester 50 together with the test piece about a rotation axis 100 facing in the vertical direction. In this state, X-rays are irradiated from the X-ray irradiation unit 11, and the X-rays that have passed through the test piece TP are detected by the X-ray detector 12, thereby performing X-ray CT imaging. Then, after the X-ray CT imaging, average Then, the camera 81 photographs the bending region of the test piece TP.

[0030] Here, the test piece TP is a printed circuit board, and has a configuration in which a board 1 and an electronic component 2 are joined by solder joints 3. In general, the solder joints 3 are arranged on the same plane on the board 1. For this reason, as shown in FIG. 8, when X-ray CT imaging is performed with the board 1 of the test piece TP arranged horizontally, the multiple solder joints 3 of the test piece TP rotate in the same plane, and metal artifacts originating from the solder joints 3 occur prominently in the image captured by the X-ray detector 12. When such artifacts occur prominently, it becomes difficult to accurately observe the observation target area of ​​the test piece TP, including the solder joints 3.

[0031] For this reason, in the X-ray CT device according to this embodiment, as shown in Fig. 9, the inclination angle of the bending tester 50 is changed by the action of the angle change mechanism 30 to change the angle between the direction in which the test force is applied to the test piece TP by the bending tester 50 and the optical axis of the X-rays. The inclination angle of the bending tester 50 at this time is set to an angle that prevents as many solder joints 3 as possible from being positioned in the path of the X-rays irradiated from the X-ray irradiation unit 11, passing through the test piece TP, and reaching the X-ray detector 12. This makes it possible to suppress the occurrence of artifacts due to metal originating from the solder joints 3 in the image captured by the X-ray detector 12.

[0032] Here, the camera 81 is connected to the base plate 57 of the bending test machine 50 via connection members 82 and 83. Therefore, even if the tilt angle of the bending test machine 50 is changed, the camera 81 can continuously capture images of the bending region of the test piece TP.

[0033] 8 and 9, the configuration in which the substrate 1 and the electronic component 2 in the test piece TP are joined by two solder joints 3 is shown as a schematic diagram, but in an actual printed circuit board, many solder joints exist, and these solder joints are generally arranged on approximately the same plane. Therefore, by tilting the test piece TP together with the bending tester 50 as in the above-mentioned embodiment, it is possible to suppress the reduction in volume caused by the solder joints being arranged on the same plane, and to suppress the occurrence of artifacts. This makes it possible to obtain high-quality X-ray CT images.

[0034] In the above-described embodiment, a printed circuit board having a configuration in which a substrate 1 and an electronic component 2 are joined by solder joints 3 is used as the test piece TP, but CFRP or GFRP may also be used as the test piece. Even in such a case, by tilting the test piece to reduce the distance that the X-rays pass through the test piece, it is possible to obtain a high-quality X-ray CT image while suppressing the occurrence of artifacts.

[0035] In the above embodiment, a three-point bending test is performed using the indenter 52 and a pair of fulcrums 51, but the present invention may be applied to a four-point bending test using a pair of indenters. Furthermore, the present invention is not limited to bending tests, and may be applied to other material tests such as tensile tests in which a test force is applied to the test piece TP.

[0036] Furthermore, in the above-described embodiment, the bending tester 50 is rotated by the rotating stage 13 disposed between the X-ray irradiation unit 11 and the X-ray detector 12. However, the bending tester 50 may be disposed on a fixed stage, and the X-ray irradiation unit 11 and the X-ray detector 12 may be rotated synchronously around the outer periphery of the bending tester 50.

[0037] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0038] (Section 1) an X-ray imaging system including an X-ray irradiation unit and an X-ray detector; a stage disposed between the X-ray irradiation unit and the X-ray detector; a rotation mechanism that relatively rotates the X-ray imaging system and the stage about a rotation axis perpendicular to an optical axis of X-rays extending from the X-ray irradiation unit to the X-ray detector; a loading mechanism that applies a test force to the test piece and is installed on the stage; In an X-ray CT apparatus comprising: An X-ray CT device comprising an angle changing mechanism that tilts the loading mechanism to displace the direction in which the loading mechanism applies a test force to the test piece from a direction perpendicular to the optical axis of the X-rays.

[0039] According to the X-ray CT device described in paragraph 1, by tilting the loading mechanism and displacing the direction in which the loading mechanism applies the test force to the test piece from a direction perpendicular to the optical axis of the X-rays, it is possible to suppress the occurrence of artifacts and obtain high-quality X-ray CT images.

[0040] (Section 2) In the X-ray CT apparatus according to claim 1, The angle changing mechanism is an X-ray CT device that changes the angle between the direction in which the test force is applied to the test piece and the optical axis of the X-rays by changing the inclination angle of the load mechanism.

[0041] According to the X-ray CT device described in paragraph 2, by adjusting the angle between the direction in which the test force is applied to the test piece and the optical axis of the X-rays to an angle that minimizes artifacts, it is possible to obtain X-ray CT images of higher image quality.

[0042] (Section 3) In the X-ray CT apparatus according to claim 1 or 2, The loading mechanism comprises a pair of fulcrums that contact the test piece, an indenter that contacts the test piece from the direction opposite to the direction in which the test piece contacts the pair of fulcrums, and a test force application mechanism that changes the distance between the pair of fulcrums and the indenter, and an X-ray CT device that performs a bending test on the test piece.

[0043] According to the X-ray CT apparatus described in the third aspect, it becomes possible to perform X-ray CT imaging in a state in which a three-point bending test has been performed.

[0044] (Section 4) In the X-ray CT apparatus according to any one of claims 1 to 3, A camera for photographing the test piece; a connection member for connecting the load mechanism and the camera to tilt the camera together with the load mechanism; The X-ray CT device further includes:

[0045] According to the X-ray CT apparatus described in the fourth aspect, it becomes possible to photograph the test piece with the camera regardless of the inclination angle of the loading mechanism.

[0046] The above description is for the purpose of explaining the embodiment of the present invention, and is not intended to limit the present invention. [Explanation of symbols]

[0047] 1 Board 2. Electronic Components 3 Solder joints 11 X-ray irradiation section 12 X-ray detector 13 Rotating stage 30 Angle change mechanism 31 Support member 34 Spindle 35 Volts 36 Nut 39 Hole 50 Bending test machine 51 Fulcrum 52 Indenter 62 Spur Gear 63 Gears 64 Threaded Rod 81 Camera 82 Connection parts 83 Connection parts TP test specimen

Claims

1. an X-ray imaging system including an X-ray irradiation unit and an X-ray detector; a stage disposed between the X-ray irradiation unit and the X-ray detector; a rotation mechanism that rotates the stage about a rotation axis perpendicular to an optical axis of X-rays extending from the X-ray irradiation unit to the X-ray detector; a loading mechanism that applies a test force to the test piece and is installed on the stage; In an X-ray CT apparatus comprising: An X-ray CT device comprising an angle change mechanism that tilts the loading mechanism relative to the stage so that the direction in which the loading mechanism applies a test force to the test piece is changed from a direction perpendicular to the optical axis of the X-rays to a direction that is not perpendicular to the optical axis of the X-rays.

2. 2. The X-ray CT apparatus according to claim 1, The angle changing mechanism changes the angle between the direction in which the test force is applied to the test piece and the optical axis of the X-rays by changing the inclination angle of the load mechanism relative to the stage.

3. 3. The X-ray CT apparatus according to claim 1, The loading mechanism includes a pair of fulcrums that contact the test piece, an indenter that contacts the test piece from a direction opposite to the direction in which the test piece contacts the pair of fulcrums, and a test force applying mechanism that changes the distance between the pair of fulcrums and the indenter, and the X-ray CT device performs a bending test on the test piece.

4. In the X-ray CT apparatus according to any one of claims 1 to 3, A camera for photographing the test piece; a connection member that connects the load mechanism and the camera to tilt the camera together with the load mechanism with respect to the stage; The X-ray CT apparatus further comprises:

Images