X-ray inspection system, control device for X-ray inspection system, and X-ray inspection method

Abstract

To provide an X-ray inspection system which can accurately grasp the internal state of a structural body that has an uneven structure.SOLUTION: An X-ray inspection system 1A includes: a detector 11 which detects the X-ray while moving in an area on the opposite side to an X-ray source 10 with a structural body 2 held therebetween; a control device 12 which controls the operation of the detector 11; and an operation mechanism 13 which operates the detector 11 on the basis of the operation mode decided by the control device 12. The control device 12 includes: a counting recognition unit 12b which recognizes the counting of X-rays incident on the detector 11 on the basis of the structure of the structural body 2; and an operation mode decision unit 12c which decides the operation mode of the detector 11 so that the counting of the X-rays incident on the detector 11 becomes equal to or greater than a prescribed amount at each position where the detector 11 moves on the basis of the recognized counting of the X-rays.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an X-ray inspection system for recognizing the internal state of a structure for inspection of the structure, a control device for the X-ray inspection system, and an X-ray inspection method.

Background Art

[0002] Conventionally, there are devices for nondestructively inspecting the interior of structures that make up social infrastructure such as roads and bridges, as well as structures that make up large vehicles, aircraft, etc. As this type of device, there is an X-ray imaging system that detects X-rays transmitted through the structure with a detector that moves vertically, generates a measurement signal based on the detected X-rays, and generates an image of the interior of the structure based on the measurement signal (see, for example, Patent Document 1).

[0003] By the way, in inspections using an X-ray inspection system as described in Patent Document 1, there is a desire to reduce the amount of noise (that is, to improve the S / N ratio). Therefore, in this X-ray inspection system, in order to make it easier for X-rays to enter the detector, the tilt angle of the detector is changed according to the height position so that the detection elements of the detector are located on a straight line passing through the X-ray source.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, structures do not always have a uniform structure. For example, the structures that make up a bridge have reinforcing steel embedded inside the concrete base material. And generally, concrete and reinforcing steel have different rates of X-ray penetration. Therefore, the areas through which X-rays penetrate differ from structure to structure.

[0006] However, the X-ray inspection system described in Patent Document 1 only changes the tilt angle of the detector relative to the X-ray source, taking into account the position of the detector. Therefore, when inspecting structures with such non-uniform structures, depending on the position of the detector relative to the structure, it may not be possible to detect a sufficient number of X-rays. Consequently, it may not be possible to obtain an image with sufficient clarity of the internal state of the structure, making it impossible to perform a proper inspection.

[0007] The present invention has been made in view of the above points, and aims to provide an X-ray inspection system, a control device for the X-ray inspection system, and an X-ray inspection method that can accurately grasp the internal state of a structure having a non-uniform structure. [Means for solving the problem]

[0008] The X-ray inspection system of the present invention is In an X-ray inspection system for recognizing the internal state of a structure for the purpose of inspecting the structure, An X-ray source for irradiating the aforementioned structure with X-rays, A detector that detects X-rays that have passed through the structure while moving across the region opposite to the X-ray source with respect to the structure, A control device for controlling the operation of the detector, An operating mechanism for operating the detector based on the operating mode determined by the control device, The system includes a data generation unit that generates data for recognizing the internal state of the structure based on the X-rays detected by the detector, The control device includes a count recognition unit that recognizes the count of X-rays incident on the detector based on the structure of the structure, and an operation mode determination unit that determines the operation mode of the detector based on the count of X-rays recognized by the count recognition unit, such that the count of X-rays incident on the detector at each position where the detector moves is equal to or greater than a predetermined amount. The control device has a structure recognition unit that recognizes the extension direction of a rod-shaped second structure located inside the first structure, which is the base material of the structure. The operation mode determination unit ensures that the count of X-rays incident on the detector is equal to or greater than a predetermined amount, and approaches a constant value. Furthermore, so as to move in a direction intersecting the extension direction of the second structure, The method is characterized by determining the operating mode of the detector.

[0009] Thus, the X-ray inspection system of the present invention recognizes the count of X-rays incident on the detector based on the structure of the structure, and determines the operating mode of the detector (e.g., moving speed, tilt angle, distance from the X-ray source, etc.) based on the recognized X-ray count so that the count of X-rays incident on the detector at each position the detector moves to is greater than or equal to a predetermined amount.

[0010] In other words, in this X-ray inspection system, the operating mode of the detector is determined so that a sufficient number of X-rays can be detected, taking into account the structure of the structure. As a result, this X-ray inspection system can detect a sufficient number of X-rays regardless of location, even for structures with non-uniform structures. Consequently, sufficient data can be generated about the internal state of such structures, allowing for an accurate understanding of their condition. Incidentally, even if the count of X-rays incident on the detector is above a certain amount and sufficient data can be generated about the internal state of the structure, if the detail of that data (for example, the clarity of the image generated by that data) varies greatly depending on the location, it may become difficult to detect anomalies based on that data. Therefore, by determining the detector's operating mode not only so that the count of X-rays incident on the detector exceeds a predetermined amount, but also so that it approaches a constant level, the large variation in the detail of the obtained data depending on the location can be suppressed, thus preventing the difficulty in detecting anomalies based on that data.

[0011] Furthermore, in the X-ray inspection system of the present invention, The operation mode determination unit determines the movement speed at the detector's position such that it becomes slower at positions where the X-ray count recognized by the count recognition unit is low. The operating mechanism preferably changes the speed of the detector so that it reaches the speed determined by the operating mode determination unit.

[0012] The slower the detector's movement speed at a given location, the higher the X-ray count detected at that location. Therefore, by determining the detector's movement speed so that it slows down at locations where the X-ray count recognized by the count recognition unit is low, it becomes easier to ensure that the X-ray count incident on the detector at each location exceeds a predetermined amount with simple control. Consequently, it becomes possible to generate sufficient data about the internal state of structures with non-uniform structures with simple control.

[0013] Furthermore, in the X-ray inspection system of the present invention, The detector includes an incident section into which X-rays that have passed through the structure are incident, The operation mode determination unit determines the tilt angle at the position of the detector such that the incident part faces the X-ray source side as the number of X-rays recognized by the count recognition unit decreases. The operation mechanism preferably changes the tilt angle of the detector so that it becomes the tilt angle determined by the operation mode determination unit.

[0014] The more the incident end of the detector, into which X-rays enter, is oriented toward the X-ray source, the higher the count of detected X-rays. Therefore, by determining the tilt angle of the detector's position so that the incident end faces the X-ray source more towards positions where the count of X-rays recognized by the count recognition unit is low, it becomes easier to ensure that the count of X-rays entering the detector at each position exceeds a predetermined amount with simple control. Consequently, it becomes possible to generate sufficient data about the internal state of structures with non-uniform structures with simple control.

[0015] Furthermore, in the X-ray inspection system of the present invention, The operation mode determination unit determines the distance from the X-ray source at the position of the detector such that the distance decreases as the number of X-rays recognized by the count recognition unit decreases. The operating mechanism preferably moves the detector so that it is the distance determined by the operating mode determination unit.

[0016] As the distance from the X-ray source increases, the X-rays emitted from the X-ray source become weaker, so the count of the detected X-rays also decreases. Therefore, if the distance from the X-ray source at the position of the detector is determined such that it becomes shorter as the count of the X-rays recognized by the count recognition unit becomes smaller, it becomes easier to make the count of the X-rays incident on the detector at each position equal to or more than a predetermined amount with simple control. As a result, with simple control, sufficient data can be generated regarding the internal state of a structure whose structure is not uniform.

[0017] Also, in the X-ray inspection system of the present invention, it is preferable that the count recognition unit estimates and recognizes in advance the count of the X-rays incident on the detector based on the structure of the structure.

[0018] Structures that make up social infrastructure such as roads and bridges can be grasped in advance by design drawings or the like. That is, for such a structure, it is also possible to estimate in advance the count of the X-rays incident on the detector using its design drawing or the like. And when such an estimation is performed in advance, for example, when continuously inspecting a plurality of structures having the same structure, it becomes possible to perform the inspection more smoothly than recognizing the count of X-rays for each structure.

[0019] Examples of the structure of the structure that can be used for estimation include, for example, the thickness of the structure between the X-ray source and the detector, the type of material constituting the structure, or the arrangement position of the material.

[0024] Generally, in structures that make up bridges and the like, there are many in which rod-shaped reinforcing bars are embedded in the concrete base material. In such a structure, some abnormality is likely to occur at the linear boundary portion between the concrete and the reinforcing bar. Therefore, there is a desire to observe the linear boundary portion in detail.

[0025] On the other hand, the detection area of ​​commonly used line sensors is often composed of multiple elements arranged horizontally in the direction of the detector's movement, making detection difficult at the boundaries between these elements. Consequently, when detection is performed while moving the detector, there is a risk that a linear region that is difficult to detect will be formed along the direction of movement. Therefore, when detection is performed with such a detector, the linear region that is difficult to detect and the linear boundary that needs to be observed in detail may be facing the same direction, making it difficult to distinguish between them.

[0026] Therefore, when a rod-shaped structure exists inside a structure, moving the detector in a direction intersecting the extension direction of that structure will cause the linear region that is difficult to detect and the linear boundary portion that you want to observe in detail to face different directions. This makes it easier to distinguish between them and to clearly understand the state of the linear boundary portion.

[0027] Furthermore, the control device for the X-ray inspection system of the present invention is 、 X in the above configuration In the control device of the line inspection system, A count recognition unit that recognizes the count of X-rays incident on the detector based on the structure of the above structure, The system is characterized by comprising: an operating mode determination unit that determines the operating mode of the detector by the operating mechanism, based on the count of X-rays recognized by the counting recognition unit, so that the count of X-rays incident on the detector at each position where the detector moves is equal to or greater than a predetermined amount.

[0028] Furthermore, the X-ray inspection method of the present invention 、 Using the X-ray inspection system with the above configuration, In an X-ray inspection method for recognizing the internal state of a structure for the purpose of inspecting the structure, 、 before The count recognition unit recognizes the count of X-rays incident on the detector based on the structure of the structure, The operation mode determination unit determines the operation mode of the detector based on the X-ray count recognized by the count recognition unit, such that the count of X-rays incident on the detector at each position where the detector moves is greater than or equal to a predetermined amount. The operating mechanism includes the step of operating the detector based on the operating mode determined by the operating mode determination unit, The data generation unit is characterized by comprising the step of generating data for recognizing the internal state of the structure based on the X-rays detected by the detector. [Brief explanation of the drawing]

[0029] [Figure 1] A schematic diagram showing the general configuration of the X-ray inspection system according to the first embodiment. [Figure 2] A schematic longitudinal cross-sectional view showing the configuration of the detector in the X-ray inspection system shown in Figure 1. [Figure 3] Perspective view of the detector and operating mechanism of the X-ray inspection system shown in Figure 1. [Figure 4] A schematic side view illustrating the operation of the detector in the X-ray inspection system shown in Figure 1. [Figure 5] A graph showing an example of the relationship between the thickness of a concrete structure, X-ray intensity, and signal-to-noise ratio. [Figure 6] Figure 1 is an explanatory diagram showing an example of the operation of the detector in the X-ray inspection system and the corresponding X-ray count. The graph on the left of the figure shows the change in X-ray count with respect to position, and the graph on the right of the figure shows the change in the movement speed of the detector with respect to position. [Figure 7] A flowchart of the X-ray inspection method using the X-ray inspection system shown in Figure 1. [Figure 8] A graph showing an example of X-ray inspection using the X-ray inspection system shown in Figure 1. [Figure 9] X-ray transmission images of a structure acquired by the X-ray inspection system shown in Figure 1, and X-ray transmission images of a structure acquired by another X-ray inspection system. [Figure 10] A schematic diagram showing the general configuration of the X-ray inspection system according to the second embodiment. [Figure 11] X-ray transmission images of the structure acquired by the X-ray inspection system shown in Figure 10, and X-ray transmission images of the structure acquired by another X-ray inspection system. [Modes for carrying out the invention]

[0030] [First Embodiment] The X-ray inspection system 1A according to the first embodiment will be described below with reference to Figures 1 to 9.

[0031] In this embodiment, we will describe the case where a block-shaped structure 2 is the object of inspection. As shown in Figure 1 and other figures, this structure 2 is a so-called reinforced concrete structure in which reinforcing bars 21 are embedded in a concrete base material 20.

[0032] In this embodiment, we will describe a case in which an X-ray inspection system 1A is used to inspect the inside of the structure 2 (particularly the area where the base material 20 and the reinforcing bars 21 are adjacent) for defects such as corrosion of the reinforcing bars 21 or fracture between the base material 20 and the reinforcing bars 21, without destroying the structure 2.

[0033] Furthermore, the structures that can be inspected by the X-ray inspection system of the present invention are not limited to the configuration described above, and any structure that can transmit X-rays is acceptable. Therefore, the structures may be, for example, structures that constitute social infrastructure other than bridges, such as roads, or structures that constitute large vehicles, aircraft, etc.

[0034] [Components of an X-ray Inspection System] First, we will explain the components of the X-ray inspection system 1A with reference to Figures 1 to 4.

[0035] As shown in Figure 1, the system includes an X-ray source 10 that irradiates the structure 2 with X-rays, a detector 11 that detects the X-rays irradiated from the X-ray source 10 and transmitted through the structure 2, a control device 12 that controls the operation of the detector 11, an operating mechanism 13 that operates the detector 11 based on the operating mode determined by the control device 12, and a data processing device 14 that performs data processing to understand the internal state of the structure 2 based on the X-rays detected by the detector 11.

[0036] The X-ray source 10 is fixed by a support stand (not shown) and emits X-rays radially toward the operating mechanism 13. In other words, the X-ray source 10 irradiates the structure 2, which is located between the X-ray source 10 and the operating mechanism 13, with X-rays.

[0037] The detector 11 is held movably by the operating mechanism 13, which will be described later. As a result, when the structure 2 is installed on the fixing device (not shown) of the X-ray inspection system 1A, the detector 11 can move freely in the area opposite to the X-ray source 10, with the structure 2 in between.

[0038] As shown in Figure 2, the detector 11 includes a rectangular parallelepiped detector housing 11a with an open side facing the X-ray source 10, a collimator 11b (incident part) positioned inside the detector housing 11a to focus the X-rays incident on the detector housing 11a, a scintillator 11c that emits light from the X-rays focused by the collimator 11b, and a photodetector 11d that generates an electrical signal based on the light from the scintillator 11c.

[0039] It should be noted that the detector of the present invention is not limited to this configuration, and any detector capable of detecting X-rays transmitted through a structure is acceptable. Therefore, for example, the components may be appropriately changed depending on the type of structure to be inspected by X-ray. Specifically, the collimator 11b in this embodiment may be omitted, and the open portion of the detector housing 11a may be used as the incident portion.

[0040] Returning to Figure 1, in this embodiment, the control device 12 is configured using an information terminal. The control device 12 has, as a function (processing unit) realized by at least one of the implemented hardware configuration and program, a structure recognition unit 12a that recognizes the structure of the structure 2 to be inspected by X-rays, a count recognition unit 12b that recognizes the count of X-rays incident on the detector 11 based on the recognized structure of the structure 2, and an operation mode determination unit 12c that determines the operation mode of the detector 11.

[0041] The structural recognition unit 12a infers and recognizes the structure of the structure 2 to be inspected by X-ray, based on design data such as a design drawing of the structure 2. Alternatively, the structural recognition unit 12a may recognize the structure of the structure 2 using data related to the structure (for example, data consisting only of numerical values) directly input by the inspector or other person.

[0042] The count recognition unit 12b estimates and recognizes the count of X-rays incident on the detector 11 in advance, based on the structure of the structure 2 recognized by the structure recognition unit 12a, and the functions and layout of the equipment constituting the X-ray inspection system, which are known values.

[0043] This is because, by making such estimations in advance, inspections can be performed more smoothly, for example, when inspecting multiple structures with similar structures in succession, compared to recognizing the X-ray count for each structure. Examples of structures that can be used for estimation include the thickness of the structure between the X-ray source and the detector, the type of material constituting the structure, or the arrangement of that material.

[0044] Furthermore, recognition by the counting and recognition unit 12b is performed for each state of the detector 11. The states of the detector 11 include the movable position of the detector 11 and the orientation (i.e., tilt angle) that the detector 11 can take.

[0045] It should be noted that the count recognition unit of the present invention is not limited to this configuration, and any unit that recognizes the count of X-rays incident on the detector is acceptable. For example, the count recognition unit may not recognize the X-ray count in advance, but rather recognize the detected X-ray count in real time, along with the status of the detector.

[0046] The operation mode determination unit 12c determines the operation mode of the detector 11 based on the X-ray count recognized by the count recognition unit 12b. The specific method for this will be described later.

[0047] As shown in Figure 3, the operating mechanism 13 includes a rectangular parallelepiped housing 13a for the operating mechanism with an open side facing the X-ray source 10, a first linear actuator 13b and a second linear actuator 13c arranged inside the housing 13a so as to extend vertically, a drive source (not shown) for driving the first linear actuator 13b and the second linear actuator 13c, and a holding plate 13d held by the first linear actuator 13b and the second linear actuator 13c.

[0048] The first linear actuators 13b come in pairs (in Figure 3, the one closer to the viewer is not shown). Each of the pair of first linear actuators 13b is positioned facing each other on the inside of two surfaces of the operating mechanism housing 13a that are later to the surface facing the X-ray source 10.

[0049] The second linear actuators 13c come in pairs (in Figure 3, the one closer to the viewer is not shown). Each of the pair of second linear actuators 13c is positioned facing each other on the inner sides of two surfaces of the operating mechanism housing 13a that are later to the surface facing the X-ray source 10. Their position is further from the X-ray source 10 than the corresponding first linear actuator 13b.

[0050] The holding plate 13d is rotatably clamped on both sides by a pair of first linear actuators 13b. Furthermore, the holding plate 13d is rotatably clamped on both sides by a pair of second linear actuators 13c at a point further from the X-ray source 10 than the portion clamped by the pair of first linear actuators 13b. The detector 11 is mounted and fixed on the upper surface of the holding plate 13d (see Figure 4).

[0051] Here, each of the pair of first linear actuators 13b operates similarly. Similarly, each of the pair of second linear actuators 13c operates similarly. However, the pair of first linear actuators 13b and the pair of second linear actuators 13c can operate independently.

[0052] Therefore, as shown in Figure 4, the holding plate 13d, which is held by the first linear actuator 13b and the second linear actuator 13c, is movable in the vertical direction and can be tilted in a side view. Consequently, the detector 11 fixed to the holding plate 13d is also movable in the vertical direction and can be tilted in a side view. Furthermore, the speed of movement and the speed of tilt change can be adjusted as appropriate.

[0053] It should be noted that the operating mechanism of the present invention is not limited to this configuration, and any mechanism that can operate the detector based on the operating mode determined by the control device is acceptable. For example, there may be only one linear actuator, or the detector may be directly attached to the housing without using a retaining plate.

[0054] Returning to Figure 1, in this embodiment, the data processing device 14 is configured using an information terminal. The data processing device 14 has, as a function (processing unit) realized by at least one of the implemented hardware configuration and program, a data generation unit 14a that generates data for recognizing the internal state of the structure 2, and an image generation unit 14b that generates an X-ray transmission image of the structure 2.

[0055] The data generation unit 14a converts the content of the detected X-rays into data for each position of the detector 11, based on the count of X-rays detected by the detector 11, the degree of change, etc.

[0056] The image generation unit 14b generates an X-ray transmission image of structure 2 based on the data generated by the data generation unit 14a (see Figure 9, etc.).

[0057] In this embodiment, an X-ray transmission image of the structure 2 is ultimately generated, and by observing this image, it is possible to inspect whether there are any defects such as tears inside the structure 2. However, if the inspection for defects is performed using, for example, a predictive model generated by machine learning, the data can be used directly instead of an image, so it is not always necessary to generate an image. In such cases, the image generation unit may be omitted.

[0058] [Method for determining the mode of operation] Next, with reference to Figures 5 and 6, the method used by the control device 12 to determine the operating mode of the detector 11 will be described.

[0059] First, before explaining the method, we will describe the factors that change the count of detected X-rays.

[0060] The graph shown in Figure 5 illustrates the relationship between the thickness of a commonly used structure, the X-ray intensity (i.e., the number of detected X-rays), and the signal-to-noise ratio (S / N ratio).

[0061] As can be seen from this graph, the more the thickness of the structure increases, the lower the X-ray intensity becomes and the worse the signal-to-noise ratio (S / N ratio) becomes (i.e., the noise increases). Even if the material of the structure is different, although the degree of change differs, the X-ray intensity decreases and the S / N ratio worsens similarly as the thickness increases. In other words, the X-ray count detected at each position of the detector varies depending on the shape of the structure, the material that makes up the structure, and the internal structure of the structure.

[0062] Furthermore, in typical X-ray inspections, X-rays from an X-ray source are not uniformly irradiated onto the structure, but rather emitted radially from a predetermined point (see, for example, Figure 1). If the structure being inspected is rectangular, and the X-ray source is positioned opposite the center of the structure, the thickness of the structure will be relatively thicker at the edges compared to the center. As a result, the number of detected X-rays will decrease, and the signal-to-noise ratio will deteriorate.

[0063] Furthermore, simply put, the faster the detector moves, the less the incident portion of the detector is facing the X-ray source, and the greater the distance between the X-ray source and the detector, the fewer X-rays are detected, and the worse the signal-to-noise ratio (S / N ratio).

[0064] Therefore, if a detector that covers the entire surface of the structure (for example, an FPD (flat panel detector)) is used to detect X-rays that have passed through the structure, the detection time is constant regardless of the area. As a result, detailed data cannot be obtained in areas where the number of detected X-rays is low.

[0065] Furthermore, when a so-called line sensor is used as a detector to detect X-rays that have passed through a structure, its movement is usually performed along a predetermined trajectory at a predetermined speed. Similarly, in areas where the count of detected X-rays is low, detailed data cannot be obtained.

[0066] Therefore, in the control device 12 of the X-ray inspection system 1A, the operation mode determination unit 12c determines the operation mode of the detector 11 (specifically, the movement speed and tilt angle of the detector 11 at each position) based on the count of X-rays incident on the detector 11 estimated and recognized by the count recognition unit 12b.

[0067] In the X-ray inspection system 1A, the count recognition unit 12b pre-determines the operating mode of the detector 11 by predicting and recognizing the X-ray count. However, the X-ray inspection system of the present invention is not limited to this configuration, and the count recognition unit may recognize the X-ray count incident on the detector in real time and thereby determine the operating mode of the detector in real time.

[0068] Then, in determining the operating mode of the detector 11, the operating mode determination unit 12c determines the operating mode such that the count of X-rays incident on the detector 11 at each position where the detector 11 moves is equal to or greater than a predetermined amount.

[0069] Specifically, as shown in Figure 6, in regions where the number of detected X-rays is high, as shown in the graph on the left side of the figure, the movement speed is increased, as shown in the movement speed on the graph on the right side of the figure, and in regions where the number of detected X-rays is low, the movement speed is decreased.

[0070] Furthermore, as shown in the schematic diagram in the center of the figure, the tilt angle of the detector 11 is changed so that the incident part of the detector 11 faces the X-ray source 10, regardless of its position.

[0071] In other words, in this X-ray inspection system 1A, the operating mode of the detector 11 is determined so that a sufficient number of X-rays can be detected, taking into account the structure of the structure 2. As a result, this X-ray inspection system 1A can detect a sufficient number of X-rays regardless of the position, even if the structure 2 has a non-uniform structure. Consequently, sufficient data can be generated about the internal state of such a structure 2, allowing for an accurate understanding of its condition.

[0072] However, even if the count of X-rays incident on the detector 11 is above a predetermined amount and sufficient data can be generated about the internal state of the structure 2, if the level of detail of that data (for example, the clarity of the image generated by that data) varies greatly depending on the location, it may become difficult to detect anomalies based on that data.

[0073] Therefore, the operation mode determination unit 12c determines the operation mode of the detector 11 not only so that the count of X-rays incident on the detector 11 is greater than or equal to a predetermined amount, but also so that it approaches a constant value. As a result, in the X-ray inspection system 1A, the large variation in the detail of the obtained data depending on the location is suppressed, thereby preventing the difficulty in detecting abnormalities based on that data.

[0074] However, if the count of X-rays incident on the detector 11 is sufficiently large at all positions where the detector 11 moves, it is not necessary to keep the count of X-rays incident on the detector 11 as close to a constant as possible.

[0075] As mentioned above, the operation mode determination unit 12c of the X-ray inspection system 1A determines the movement speed of the detector 11 at each position so that it becomes slower at positions where the count of X-rays recognized by the count recognition unit 12b is low. The operation mechanism 13 then changes the movement speed of the detector 11 according to the determined operation mode. This is to make it easier to ensure that the count of X-rays incident on the detector at each position is above a predetermined amount with simple control.

[0076] However, the operation mode determination unit of the control device for the X-ray inspection system of the present invention is not limited to this configuration, and it is sufficient that it determines the operation mode of the detector based on the X-ray count recognized by the count recognition unit, such that the count of X-rays incident on the detector at each position where the detector moves is equal to or greater than a predetermined amount.

[0077] Therefore, for example, the operation mode determination unit may determine the tilt angle at the detector's position so that the incident part of the detector always faces the X-ray source, rather than determining it as the operation mode determination unit 12c in this embodiment. Instead, it may determine it so that the incident part of the detector faces the X-ray source only at positions where the count of X-rays recognized by the count recognition unit is low.

[0078] Furthermore, for example, the operation mode determination unit may determine the distance from the X-ray source at the detector's position such that the distance decreases as the number of X-rays recognized by the count recognition unit decreases.

[0079] Furthermore, the operation mode determination unit only needs to determine the operation mode of the detector by combining changes in the moving speed, tilt angle, and distance from the X-ray source, based on the X-ray count recognized by the count recognition unit, so that the count of X-rays incident on the detector at each position the detector moves is equal to or greater than a predetermined amount.

[0080] Furthermore, the operation mode determination unit may refer to the distance from the X-ray optical axis to the detector as a factor in determining the change in movement speed, tilt angle, and distance from the X-ray source.

[0081] This is because, generally, X-rays from an X-ray source are emitted radially, and in such cases, the count of detected X-rays fluctuates depending on the distance between the central axis (i.e., the optical axis of the X-rays) and the detector. Furthermore, with this configuration, it becomes easier to ensure that the count of X-rays incident on the detector at each position the detector moves is above a predetermined amount with even simpler control.

[0082] [Inspection Procedure] Next, referring to Figures 1 and 7, an X-ray inspection method will be described using the X-ray inspection system 1A to inspect structure 2 and to recognize the internal state of structure 2.

[0083] In this X-ray inspection method, first, the structural recognition unit 12a of the control device 12 recognizes the structure of the structure 2 that is the target of the X-ray inspection (Figure 9 / STEP 1).

[0084] Specifically, the structural recognition unit 12a infers and recognizes the structure of the structure 2 to be inspected by X-ray, based on the design data of the structure 2. Alternatively, the structural recognition unit 12a may recognize the structure of the structure 2 using structural data (for example, data consisting only of numerical values) directly input by the inspector or other user. Furthermore, if the system is configured to determine the operating mode by measuring the X-ray count in real time, this STEP 1 may be omitted.

[0085] Next, the count recognition unit 12b of the control device 12 recognizes the count of X-rays incident on the detector 11 based on the recognized structure of the structure 2 (Figure 9 / STEP2).

[0086] Next, the operation mode determination unit 12c of the control device 12 determines the operation mode of the detector 11 based on the recognized X-ray count (Figure 9 / STEP3).

[0087] Specifically, as described above, the operation mode determination unit 12c determines the operation mode of the detector 11 (specifically, the movement speed and tilt angle of the detector 11 at each position) so that the count of X-rays incident on the detector 11 is not only equal to or greater than a predetermined amount, but also approaches a constant value.

[0088] Next, the operating mechanism 13 operates the detector 11 based on the determined operating mode (Figure 9 / STEP4).

[0089] Next, the data generation unit 14a of the data processing device 14 generates data to recognize the internal state of the structure 2 based on the count of detected X-rays (Figure 9 / STEP 5).

[0090] Next, the image generation unit 14b of the data processing device 14 generates an image based on the generated data (Figure 9 / STEP6), and the process ends.

[0091] As mentioned above, if the inspection is to determine whether there are any defects such as fractures inside structure 2 using machine learning rather than image observation, then instead of STEP 6, the data will be input into a predictive model generated by machine learning, and the inspection results will be output.

[0092] [Experimental data] Next, referring to Figures 8 and 9, experimental data obtained by the X-ray inspection method performed using the aforementioned X-ray inspection system 1A are shown.

[0093] The graph shown in Figure 8 represents the average signal-to-noise ratio of the entire inspection area with respect to the thickness of the structure 2 (a concrete base material 20 in which reinforcing bars 21 are embedded). The data was measured using an X-ray inspection method performed with the X-ray inspection system 1A, with a line sensor as the detector 11 (Example 1), and data was measured using an FPD (flat panel detector) that covers the entire surface of the structure 2 as the detector 11 (Comparative Example 1).

[0094] As can be seen from this data, in Example 1 of this embodiment, when the thickness of the structure 2 exceeds approximately 600 mm, the signal-to-noise ratio is better than that of Comparative Example 1.

[0095] Furthermore, the images shown in Figure 9 correspond to points A to F in the graph shown in Figure 8, with A to C being images related to Example 1 and D to F being images related to Comparative Example 1.

[0096] As is clear from these images, when the thickness of the structure 2 is the same, Example 1 of this embodiment produces a clearer image compared to Comparative Example 1.

[0097] [Second Embodiment] The X-ray inspection system 1B according to the second embodiment will be described below with reference to Figure 10.

[0098] The X-ray inspection system 1B of this embodiment has the same configuration as the X-ray inspection system 1A of the first embodiment, except that the method for determining the operating mode of the detector 11 is different. Therefore, in the following description, only the method for determining the operating mode will be described. Also, components that are the same as or corresponding to components of the X-ray inspection system 1A of the first embodiment will be denoted by the same reference numerals, and detailed descriptions will be omitted.

[0099] [Method for determining the mode of operation] Generally, in structures such as bridges, many have bar-shaped reinforcing steel embedded in the concrete base material (see, for example, Figures 1 and 10). In such structures, abnormalities are likely to occur at the linear boundary between the concrete and the reinforcing steel. Therefore, there is a demand to observe this linear boundary in detail.

[0100] On the other hand, the detection area of ​​commonly used detectors is often composed of multiple elements arranged horizontally in the direction of the detector's movement, making detection difficult at the boundaries between these elements. Consequently, when detection is performed while moving the detector, there is a risk that a linear region that is difficult to detect will be formed along the direction of movement. Therefore, when detection is performed with such a detector, the linear region that is difficult to detect and the linear boundary area that needs to be observed in detail may be facing the same direction, making it difficult to distinguish between them.

[0101] Therefore, in the X-ray inspection system 1B, when determining the operating mode of the detector 11, in addition to ensuring that the count of X-rays incident on the detector 11 is equal to or greater than a predetermined amount and approaches a constant, similar to the X-ray inspection system 1A of the first embodiment, the operating mode of the detector 11 is determined by giving greater consideration to the structure of the structure 2.

[0102] Specifically, first, when the structural recognition unit 12a of the control device 12 recognizes the structure of the structure 2, it confirms the extension direction of the rod-shaped reinforcing bars 21 (second structure) that are placed inside the concrete (first structure), which is the base material 20 of the structure 2.

[0103] Then, taking into consideration the direction of extension, the operation mode determination unit 12c of the control device 12 determines the operation mode of the detector 11 so that the count of X-rays incident on the detector 11 is equal to or greater than a predetermined amount, approaches a constant value, and moves in a direction intersecting the direction of extension of the reinforcing bar 21, as shown in Figure 10.

[0104] Thus, when a rod-shaped structure exists inside structure 2, moving the detector in a direction intersecting the extension direction of that structure will cause the linear region that is difficult to detect and the linear boundary portion that you want to observe in detail to face different directions. This makes it easier to distinguish between them and to clearly understand the state of the linear boundary portion.

[0105] In addition, in the X-ray inspection system 1B, the operation mode determination unit 12c does not need to make the count of X-rays incident on the detector 11 as close to a constant as possible if the count of X-rays incident on the detector 11 is sufficiently large at all positions where the detector 11 moves.

[0106] [Experimental data] Next, referring to Figure 11, experimental data obtained by the X-ray inspection method using the aforementioned X-ray inspection system 1B is shown.

[0107] Of the images shown in Figure 11, the image on the left (Example 2) was acquired by moving the detector 11 so that it intersects with the extension direction of the reinforcing bar 21, while the image on the right (Comparative Example 2) was acquired by moving the detector 11 along the extension direction of the reinforcing bar 21.

[0108] As is clear from these images, in Example 2 of this embodiment, unlike Comparative Example 2, the direction in which the boundary portion between the base material 20 and the reinforcing bar 21, which is the area to be observed, extends intersects with the direction in which the boundary portion due to the boundary of the light-receiving element 11d extends. Therefore, the state of the area to be observed can be observed more clearly compared to the image of Comparative Example 2.

[0109] [Other embodiments] Although the illustrated embodiments have been described above, the present invention is not limited to these embodiments.

[0110] For example, in the above embodiment, the X-ray inspection systems 1A and 1B are configured with equipment installed in one location. However, the X-ray inspection system of the present invention is not limited to such a configuration, and the location where the constituent equipment is installed may be set as appropriate.

[0111] Therefore, for example, the equipment that performs the actual inspection work and the equipment that processes the data may be placed in different locations, and these devices may be configured to communicate with each other via the Internet, public network, etc. Specifically, at least one of the control device 12 and the data processing device 14 in this embodiment may be placed in a different location from the X-ray source 10, the detector 11, and the operating mechanism 13.

[0112] Furthermore, if the equipment that performs the actual inspection work and the equipment that processes the data are located in different places, the people who operate these devices do not necessarily have to be the same. In other words, with the X-ray inspection system of the present invention, it is not necessary for a single person to perform all of the X-ray inspection.

[0113] Therefore, for example, the person who analyzes the structure of the structure and provides data on the operation of the detector, the person who uses the provided data to investigate the count of X-rays that have passed through the structure, and the person who performs analysis based on the investigated X-ray count to inspect the structure may all be different.

[0114] Specifically, the person who possesses the control device 12 shown in Figure 1, the person who uses the X-ray source 10, detector 11, and operating mechanism 13 in the above embodiment, and the person who possesses the data processing device 14 may be different. In this case, the control device 12 only needs to have at least a counting recognition unit 12b and an operating mode determination unit 12c. [Explanation of symbols]

[0115] 1A, 1B...X-ray inspection system, 2...Structure, 10...X-ray source, 11...Detector, 11a...Detector housing, 11b...Collimator (incident part), 11c...Scintillator, 11d...Photodetector, 12...Control device, 12a...Structure recognition unit, 12b...Counting recognition unit, 12c...Operation mode determination unit, 13...Operation mechanism, 13a...Operation mechanism housing, 13b...First linear actuator, 13c...Second linear actuator, 13d...Holding plate, 14...Data processing device, 14a...Data generation unit, 14b...Image generation unit, 20...Base material, 21...Reinforcement bar.

Claims

1. In an X-ray inspection system for recognizing the internal state of a structure for the purpose of inspecting the structure, An X-ray source for irradiating the aforementioned structure with X-rays, A detector that detects X-rays that have passed through the structure while moving through the region on the opposite side of the structure from the X-ray source, A control device for controlling the operation of the detector, An operating mechanism for operating the detector based on the operating mode determined by the control device, The system includes a data generation unit that generates data for recognizing the internal state of the structure based on the X-rays detected by the detector, The control device includes a count recognition unit that recognizes the count of X-rays incident on the detector based on the structure of the structure, and an operation mode determination unit that determines the operation mode of the detector based on the count of X-rays recognized by the count recognition unit, such that the count of X-rays incident on the detector at each position where the detector moves is equal to or greater than a predetermined amount. The control device has a structure recognition unit that recognizes the extension direction of a rod-shaped second structure located inside the first structure, which is the base material of the structure. The X-ray inspection system is characterized in that the operation mode determination unit determines the operation mode of the detector such that the count of X-rays incident on the detector is equal to or greater than a predetermined amount, approaches a constant value, and moves in a direction intersecting the extension direction of the second structure.

2. In the X-ray inspection system according to claim 1, The X-ray inspection system is characterized in that the count recognition unit estimates and recognizes the count of X-rays incident on the detector in advance based on the structure of the structure.

3. In the control device for the X-ray inspection system according to claim 1, A count recognition unit that recognizes the count of X-rays incident on the detector based on the structure of the above structure, A control device for an X-ray inspection system, comprising: an operating mode determination unit that determines the operating mode of the detector by the operating mechanism so that the count of X-rays incident on the detector at each position where the detector moves is equal to or greater than a predetermined amount, based on the count of X-rays recognized by the count recognition unit.

4. An X-ray inspection method for recognizing the internal state of a structure for inspection of the structure, using the X-ray inspection system described in claim 1, The count recognition unit performs the step of recognizing the count of X-rays incident on the detector based on the structure of the structure, The operation mode determination unit determines the operation mode of the detector based on the X-ray count recognized by the count recognition unit, such that the count of X-rays incident on the detector at each position where the detector moves is equal to or greater than a predetermined amount. The operating mechanism includes the step of operating the detector based on the operating mode determined by the operating mode determination unit, An X-ray inspection method characterized in that the data generation unit generates data for recognizing the internal state of the structure based on the X-rays detected by the detector.

Images