X-ray examination apparatus and method of adjusting thereof

Abstract

The present application provides an X-ray inspection apparatus and an adjustment method thereof. The X-ray inspection apparatus includes: a conveyance section that conveys an article; an X-ray source that irradiates the article with X-rays; an X-ray detection section that can detect the X-rays by a photon counting method and discriminate the photon energies of the detected X-rays into two or more energy regions based on an arbitrary threshold value; a threshold value setting section that sets the arbitrary threshold value; an X-ray image generation section that generates two or more X-ray transmission images corresponding to the two or more energy regions based on the detection results of the X-ray detection section; and an inspection section that performs an inspection of the article based on the X-rays that have passed through the article and detected by the X-ray detection section, wherein the threshold value setting section sets the arbitrary threshold value based on the gradation of the two or more X-ray transmission images.

Description

Technical Field

[0001] This disclosure relates to X-ray inspection apparatus and adjustment methods thereof. Background Technology

[0002] As a conventional X-ray inspection device, for example, the device described in Japanese Patent No. 6569070 is known. The X-ray inspection device described in Japanese Patent No. 6569070 includes: an X-ray detection unit that detects each photon of X-rays passing through the object being measured by distinguishing the energy of the photons into two or more energy regions with reference to a predetermined number of energy thresholds; a storage unit that stores each of the multiple types of objects being measured in a way that directly or indirectly associates the object with an energy threshold; a threshold setting unit that, with reference to the storage unit, maintains a threshold corresponding to the type of object being measured, determined based on input information, in a manner that allows the X-ray detection unit to use it as a predetermined threshold; and an inspection unit that inspects the object being measured based on the number of photons detected by the X-ray detection unit in each of the predetermined energy regions, or an amount corresponding to the number of photons.

[0003] In the X-ray inspection apparatus described above, an energy threshold corresponding to the physical characteristics of the object being measured, pre-stored in a storage unit, can be used. However, due to factors such as inspection conditions of the object (e.g., transport speed of the object), deviations in the performance of the X-ray inspection apparatus itself, and the condition of the X-ray inspection apparatus (e.g., changes in energy distribution due to deterioration of the X-ray source), there are cases where the pre-stored energy threshold is not optimal. Therefore, the inspection accuracy of the object being measured may decrease due to the aforementioned inspection conditions. Summary of the Invention

[0004] One objective of this disclosure is to provide an X-ray inspection apparatus and its adjustment method that can inspect articles with excellent accuracy even if the inspection conditions or other factors change.

[0005] An X-ray inspection apparatus according to one aspect of this disclosure includes: a transport unit for transporting an article; an X-ray source for irradiating the article with X-rays; an X-ray detection unit capable of detecting X-rays by photon counting and distinguishing the photon energy of the detected X-rays into two or more energy regions based on an arbitrary threshold; a threshold setting unit for setting an arbitrary threshold; an X-ray image generation unit for generating two or more X-ray transmission images corresponding to the two or more energy regions based on the detection result of the X-rays by the X-ray detection unit; and an inspection unit for inspecting the article based on the X-rays transmitted through the article detected by the X-ray detection unit, wherein the threshold setting unit sets the arbitrary threshold based on the intensity of the two or more X-ray transmission images.

[0006] Another aspect of this disclosure relates to an X-ray inspection apparatus comprising: a transport unit for transporting an article; an X-ray source for irradiating the article with X-rays; an X-ray detection unit capable of detecting X-rays by photon counting; and a control unit into which the detection results of the X-ray detection unit are input. The control unit comprises: a discrimination unit for distinguishing the photon energy of the X-rays detected by the X-ray detection unit into two or more energy regions based on an arbitrary threshold; a threshold setting unit for setting an arbitrary threshold; an X-ray image generation unit for generating two or more X-ray transmission images corresponding to the two or more energy regions based on the detection results of the X-rays by the X-ray detection unit; and an inspection unit for inspecting the article based on the X-rays transmitted through the article detected by the X-ray detection unit, wherein the threshold setting unit sets the arbitrary threshold based on the intensity of the two or more X-ray transmission images.

[0007] According to these X-ray inspection devices, the threshold setting unit sets an arbitrary threshold based on the density of two or more X-ray transmission images. Therefore, for example, when the inspection conditions of the item are changed, the arbitrary threshold may sometimes change. That is, the threshold setting unit can set an appropriate threshold corresponding to changes in inspection conditions, etc. Thus, even if the inspection conditions of the item are changed, the item can be inspected with excellent accuracy.

[0008] The X-ray detection unit or discrimination unit can also distinguish photon energy into a first energy region, a second energy region, and a third energy region that is lower than the first and second energy regions. In this case, for example, by excluding the energy regions containing the most noise from the first to the third energy regions, the inspection accuracy of the article can be improved.

[0009] Any threshold can also be determined based on the difference in intensity between two or more X-ray transmission images within a predetermined range. In this case, it is easy to detect whether the item contains foreign objects, etc.

[0010] Any threshold can also be a value obtained by adding a correction value to the threshold. In this case, the accuracy of item inspection can be improved.

[0011] Alternatively, if the intensity difference between two or more X-ray transmission images is outside a predetermined range, after the threshold setting unit changes any threshold, the X-ray image generation unit generates two or more other X-ray transmission images corresponding to two or more other energy regions identified based on the changed threshold. The threshold setting unit then determines whether the intensity difference between the other two or more X-ray transmission images is within a predetermined range. In this case, the threshold setting unit can accurately set any threshold within the predetermined range for the intensity difference between two or more X-ray transmission images.

[0012] Alternatively, the X-ray image generation unit generates two or more X-ray transmission images corresponding to two or more other energy regions, identified based on thresholds different from the arbitrary threshold. The threshold setting unit compares the intensity difference between the two or more X-ray transmission images with the intensity difference between the other two or more X-ray transmission images. In this case, the threshold setting unit can easily determine whether the arbitrary threshold is appropriate by comparing the differences between them.

[0013] Another aspect of this disclosure relates to an adjustment method for an X-ray inspection apparatus comprising: an X-ray irradiation step, irradiating an inspection chamber disposed in a frame with X-rays; an X-ray detection step, detecting X-rays by photon counting; a discrimination step, discriminating the photon energy of the detected X-rays into two or more energy regions based on an arbitrary threshold; an image generation step, generating two or more X-ray transmission images corresponding to the two or more energy regions using the photon energy; and a threshold setting step, setting an arbitrary threshold based on the intensity of the two or more X-ray transmission images.

[0014] According to this adjustment method, in the threshold setting step, an arbitrary threshold is set based on the density of two or more X-ray transmission images. Therefore, for example, when the inspection conditions of the item are changed, the arbitrary threshold may sometimes change. That is, the arbitrary threshold can be changed to an appropriate threshold corresponding to the change in inspection conditions, etc. According to the X-ray inspection apparatus implementing this adjustment method, even if the inspection conditions of the item are changed, the item can be inspected with excellent accuracy.

[0015] If, during the threshold setting step, the difference in intensity between two or more X-ray transmission images is outside a predetermined range, arbitrary threshold changes, discrimination steps, image generation steps, and threshold setting steps are performed until the difference falls within the predetermined range. In this case, it is possible to set any threshold within the predetermined range for the difference in intensity between two or more X-ray transmission images with excellent accuracy.

[0016] Alternatively, in the discrimination step, photon energy is discriminated into two or more energy regions based on thresholds different from the arbitrary threshold. In the image generation step, two or more X-ray transmission images corresponding to the other two or more energy regions are generated. In the threshold setting step, the intensity difference between the two or more X-ray transmission images is compared with the intensity difference between the other two or more X-ray transmission images. In this case, the appropriateness of any arbitrary threshold can be easily determined by comparing the aforementioned differences.

[0017] According to one aspect of this disclosure, an X-ray inspection apparatus and its adjustment method can be provided that can inspect articles with excellent accuracy even when the inspection conditions of the articles are changed. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an X-ray inspection apparatus according to one embodiment.

[0019] Figure 2 yes Figure 1 The diagram shows the internal structure of the shielding box.

[0020] Figure 3 This is a functional diagram of the control unit.

[0021] Figure 4 (a) is a diagram showing the first transmission image. Figure 4 (b) is a diagram showing the second transmission image.

[0022] Figure 5 This is a diagram showing the difference image.

[0023] Figure 6 This is a flowchart illustrating the adjustment method of an X-ray inspection device.

[0024] Figure 7 This is a flowchart illustrating the adjustment method of an X-ray inspection device.

[0025] Figure 8 This is a functional configuration diagram of the control unit involved in the modified example. Detailed Implementation

[0026] Hereinafter, suitable embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that in the description of the drawings, the same or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted.

[0027] like Figure 1 As shown, the X-ray inspection device 1 includes a main body 2, support feet 3, a shielding box 4, a conveying unit 5, an X-ray irradiation unit 6, an X-ray detection unit 7, a display and operation unit 8, and a control unit 10. The X-ray inspection device 1 generates an X-ray transmission image of the item G while conveying it, and inspects the item G based on this image. The item G before inspection is fed into the X-ray inspection device 1 by an infeed conveyor 51. The item G after inspection is discharged from the X-ray inspection device 1 by an outfeed conveyor 52. Items G deemed defective by the X-ray inspection device 1 are distributed off the production line by a distribution device (not shown) located downstream of the outfeed conveyor 52. Items G deemed acceptable by the X-ray inspection device 1 pass directly through this distribution device. In this embodiment, the item G is cereal.

[0028] The main body 2 houses the control unit 10, etc. Support feet 3 support the main body 2. A shielding box 4 is installed on the main body 2. The shielding box 4 is a frame that prevents X-rays (electromagnetic waves) from leaking to the outside. An inspection chamber R for inspecting an item G using X-rays is installed inside the shielding box 4. The shielding box 4 has an inlet 4a and an outlet 4b. Before inspection, the item G is fed into the inspection chamber R from the inlet conveyor 51 via the inlet 4a. After inspection, the item G is sent out from the inspection chamber R via the outlet 4b to the outlet conveyor 52. X-ray shielding curtains (not shown) are installed at both the inlet 4a and outlet 4b to prevent X-ray leakage.

[0029] The conveying unit 5 is a component that conveys the item G and is configured to pass through the center of the shielded box 4. The conveying unit 5 conveys the item G along the conveying direction A from the inlet 4a through the inspection chamber R to the outlet 4b. The conveying unit 5 is, for example, a belt conveyor installed between the inlet 4a and the outlet 4b. It should be noted that the conveying unit 5, as a belt conveyor, may also protrude outward relative to the inlet 4a and the outlet 4b.

[0030] like Figure 1 and Figure 2 As shown, the X-ray irradiation unit 6 is an electromagnetic wave irradiation unit (X-ray source) disposed within the shielding box 4. The X-ray irradiation unit 6 includes, for example, an X-ray tube that emits X-rays and an aperture section that allows the X-rays emitted from the X-ray tube to fan out in a plane perpendicular to the transport direction A. The X-rays irradiated by the X-ray irradiation unit 6 include X-rays in various energy ranges from low energy (long wavelength) to high energy (short wavelength). Therefore, the X-ray irradiation unit 6 irradiates the article G transported by the transport unit 5 with X-rays in multiple energy ranges. It should be noted that the terms "low" and "high" in the above-mentioned low energy and high energy refer to "low" and "high" relative to each of the multiple energy ranges irradiated by the X-ray irradiation unit 6, and do not represent specific ranges.

[0031] The X-ray detection unit 7 is a sensor component that detects electromagnetic waves. The X-ray detection unit 7 is disposed within the shielding box 4 and positioned opposite the X-ray irradiation unit 6 in the vertical direction. The X-ray detection unit 7 can detect X-rays in specific energy regions, or it can detect X-rays by photon counting. The X-ray detection unit 7 can be a direct conversion type detection unit or an indirect conversion type detection unit. In this embodiment, the X-ray detection unit 7 is a direct conversion type detection unit that can detect X-rays by photon counting, for example, including sensors (multi-energy sensors) that detect X-rays in multiple energy regions that pass through the article G. These sensors are arranged, for example, at least in a direction orthogonal to the transport direction and the vertical direction of the transport unit 5 (width direction). The components may also be arranged not only in the width direction but also in the transport direction. That is, the X-ray detection unit 7 may include a row of sensors or a group of sensors arranged in two dimensions. The aforementioned sensors are, for example, photon detection type sensors such as CdTe semiconductor detectors.

[0032] In the X-ray detection unit 7, for example, electron-hole pairs are generated by the arrival of photons from X-rays. Photon counting is performed based on the energy (photon energy) obtained at this time.

[0033] The X-ray detection unit 7 distinguishes the photon energy of detected X-rays into two or more energy regions based on an arbitrary threshold. Therefore, the X-ray detection unit 7 can count photons in each energy region. The X-ray detection unit 7 outputs a signal (detection result signal) corresponding to the detection result of the X-rays and after differentiation to the control unit 10. In this embodiment, the X-ray detection unit 7 uses an arbitrary threshold to distinguish the photon energy of detected X-rays into at least a first energy region and a second energy region higher than the first energy region. The arbitrary threshold is, for example, one or more values ​​(unit: keV) set by the control unit 10. Therefore, the first energy region and the second energy region can be distinguished based on a single threshold, or they can be distinguished based on different thresholds (e.g., a first threshold and a second threshold different from the first threshold). In the latter case, one or more energy regions may exist between the first energy region and the second energy region. For example, the X-ray detection unit 7 may also distinguish the aforementioned photon energy into a first energy region, a second energy region, and a third energy region lower than the first and second energy regions. The display operation unit 8 can appropriately confirm the aforementioned arbitrary thresholds and their quantities based on changes in the type of item G, changes in inspection conditions, etc. It should be noted that the method for setting arbitrary thresholds will be described later.

[0034] like Figure 1As shown, the display operation unit 8 is a component (display unit) provided on the main body 2 of the device. The display operation unit 8 displays various information and receives various input operations from the outside. The display operation unit 8 is, for example, a liquid crystal display (LCD) that displays an operation screen as a touch panel. In this case, the operator can input various conditions through the display operation unit 8. As an input operation, for example, receiving the check unit 23 (see reference 10) included in the control unit 10. Figure 3 The selection operation involves choosing an image (details to be described later) for inspecting item G. This allows for the appropriate acquisition of the desired inspection results.

[0035] The control unit 10, which receives the detection results from the X-ray detection unit 7, is located within the main body 2 of the device. The control unit 10 controls the operation of each part of the X-ray inspection apparatus 1 (in this embodiment, this includes the transport unit 5, the X-ray irradiation unit 6, the X-ray detection unit 7, the display operation unit 8, and a dispensing device (not shown) located downstream of the X-ray inspection apparatus 1). It should be noted that the dispensing device is a device that excludes inspected items (articles) that are determined to be defective during image inspection by the X-ray inspection apparatus 1 from the transport path. A program for controlling the X-ray inspection apparatus 1 is recorded in the ROM.

[0036] Figure 3 This is a functional diagram of the control unit. For example... Figure 3 As shown, the control unit 10 includes an X-ray image generation unit 21, a threshold setting unit 22, an inspection unit 23, a judgment unit 24, an output unit 25, and a storage unit 26.

[0037] The X-ray image generation unit 21 is a component that unfolds the signal output from the X-ray detection unit 7 (e.g., the detection result signal described above) into a two-dimensional image in memory. The X-ray image generation unit 21 is primarily composed of a GPU (Graphics Processing Unit). The memory for unfolding the two-dimensional image is, for example, the memory included in the GPU, but is not limited thereto. The X-ray image generation unit 21 generates, for example, two or more X-ray transmission images corresponding to two or more energy regions based on the X-ray detection result from the X-ray detection unit 7. Each X-ray transmission image can be an image used for inspecting the item G (hereinafter, sometimes simply referred to as an "inspection image"), or an image used to set any of the aforementioned thresholds (hereinafter, sometimes simply referred to as a "threshold setting image"). The inspection image is generated during the inspection of the item G by the X-ray inspection apparatus 1. The threshold setting image is generated, for example, during the setting or adjustment of the X-ray inspection apparatus 1 (e.g., during the calibration of the X-ray inspection apparatus 1). It should be noted that the X-ray image generation unit 21 may, for example, generate an overall transmission image corresponding to all X-rays in the above-mentioned multiple energy regions based on the above-mentioned detection results as an X-ray transmission image.

[0038] In this embodiment, the X-ray image generation unit 21 generates a first examination image P1 corresponding to the X-rays in the first energy region (refer to...). Figure 4 (a) and the second examination image P2 corresponding to the X-rays in the second energy region mentioned above (refer to...). Figure 4 (b)), and the difference image P3 obtained by subtraction processing of the first inspection image P1 and the second inspection image P2 (see reference). Figure 5 The X-ray image generation unit 21 can generate a first setting image corresponding to the X-rays in the first energy region and a second setting image corresponding to the X-rays in the second energy region as threshold setting images.

[0039] The first inspection image P1 is generated, for example, based on a portion of the information included in the detection result signal. The second inspection image P2 is generated, for example, based on another portion of the information included in the detection result signal. The X-ray image generation unit 21 may also generate the first inspection image P1 based on the overall transmission image and the second inspection image P2. In this case, the first inspection image P1 is generated, for example, based on the difference data between the data used to generate the overall transmission image and the data used to generate the second inspection image P2. Alternatively, the X-ray image generation unit 21 may also generate the second inspection image P2 based on the overall transmission image and the first inspection image P1. In this case, the second inspection image P2 is generated, for example, based on the difference data between the data used to generate the overall transmission image and the data used to generate the first inspection image P1. The item G and the background other than the item G are displayed in the first inspection image P1 and the second inspection image P2, respectively. Figure 4 As shown in example (a), the first inspection image P1 is darker overall compared to the second inspection image P2. On the other hand, as... Figure 4 As shown in example (b), the second inspection image P2 is brighter overall compared to the first inspection image P1. In this embodiment, the comparison of the brightness of the first inspection image P1 and the second inspection image P2 is equivalent to the comparison of the brightness of the item G displayed in the first inspection image P1 and the brightness of the item G displayed in the second inspection image P2.

[0040] The differential image P3 is, for example, an image (energy analysis image) generated by performing image processing on at least one of the first inspection image P1 and the second inspection image P2 using an image processing algorithm. The image processing algorithm is a model representing the processing procedure performed on at least one of the first inspection image P1 and the second inspection image P2. The image processing algorithm consists of one image processing filter or a combination of multiple image processing filters. Multiple image processing algorithms can be obtained externally via a network such as the Internet. Furthermore, multiple image processing algorithms can also be obtained from external storage media such as USB flash drives or removable hard drives. At least one or more of the multiple image processing algorithms can be automatically generated from multiple image processing filters using a method applying the mechanisms of heredity and evolution in the biological world, i.e., a genetic algorithm (GA), based on the specifications or inspection conditions of the X-ray inspection device 1. At least a portion of the multiple image processing algorithms can also be appropriately set by the operator through the display operation unit 8. The image processing algorithm used for the first inspection image P1 can also be different from the image processing algorithm used for the second inspection image P2. For example, in order to make the brightness of the first inspection image P1 consistent with the brightness of the second inspection image P2, a process of changing the brightness of one of the first inspection image P1 and the second inspection image P2 can be implemented. As such a process, for example, as described in Japanese Patent Application No. 2021-195926, a process utilizing brightness distribution can be implemented.

[0041] The X-ray image generation unit 21 can also use a program automatically set through machine learning instead of the image processing algorithm described above. Such a program is a predictive model (learned model) generated through machine learning, which is an inference program embedding the parameters (learned parameters) ultimately obtained through machine learning. Examples of machine learning used for learned models include neural networks, support vector machines, and genetic algorithms. The learned model can include convolutional neural networks or neural networks with multiple layers (e.g., eight or more layers). That is, a learned model equivalent to the above program can also be generated through deep learning.

[0042] The threshold setting unit 22 sets an arbitrary threshold based on the intensity (brightness) of two or more X-ray transmission images. The threshold setting unit 22 sets the arbitrary threshold based on a threshold where the intensity difference between the first setting image and the second setting image is within a predetermined range. First, the threshold setting unit 22 sets a threshold (provisional threshold) where the difference (brightness difference) between the background brightness (first background brightness = B1) of the first setting image and the background brightness (second background brightness = B2) of the second setting image is within a predetermined range. The predetermined background brightness of the X-ray transmission image is, for example, the value obtained by dividing the total brightness of each pixel included in the image by the number of pixels. In this embodiment, the brightness difference is equivalent to the value obtained by dividing the absolute value of the difference between the first background brightness and the second background brightness (|B2-B1|) by the total of the first background brightness and the second background brightness (B1+B2) (|B2-B1| / (B1+B2)). In this embodiment, if the brightness difference is 0.05 or less, it is determined that the brightness difference is within the predetermined range; however, this is not a limitation. Next, the threshold setting unit 22 sets an arbitrary threshold by adding a correction value (unit: keV) to the obtained provisional threshold. The correction value is, for example, an arbitrary value determined by the operator through the display operation unit 8, etc. The correction value is, for example, -10keV or more and 10keV or less. It should be noted that the correction value can also be 0. That is, the arbitrary threshold can also be the above-mentioned provisional threshold.

[0043] Before setting any threshold (i.e., when the difference in intensity between two or more X-ray transmission images is outside a predetermined range), the threshold setting unit 22 changes the threshold. If the first background brightness is greater than the second background brightness (B1 > B2), the threshold setting unit 22 performs a correction that decreases the threshold just used. If the first background brightness is less than the second background brightness (B1 < B2), the threshold setting unit 22 performs a correction that increases the threshold just used. The decrease and increase values ​​of the threshold are not particularly limited. Next, the X-ray image generation unit 21 generates two or more other X-ray transmission images (other first setting images and other second setting images) corresponding to two or more other energy regions identified based on the changed threshold. The other first setting images and other second setting images are generated after the aforementioned first setting images and second setting images. Therefore, the aforementioned first setting images and second setting images are sometimes referred to below as the previous setting images.

[0044] When generating two or more other X-ray transmission images, the threshold setting unit 22 determines whether the intensity difference between the two or more other X-ray transmission images is within a predetermined range. In this embodiment, the threshold setting unit 22 determines whether the difference (other brightness difference) between the background brightness of the other first setting image and the background brightness of the other second setting image is within a predetermined range. The X-ray image generation unit 21 and the threshold setting unit 22 repeatedly determine whether the intensity difference between the newly generated first setting image and the second setting image is within a predetermined range before setting an arbitrary threshold. Thus, the threshold setting unit 22 searches for an arbitrary threshold. It should be noted that in the search for an arbitrary threshold, the initially used threshold (initial threshold) is determined, for example, based on the tube voltage of the X-ray detection unit 7, but it is not limited to this. The initial threshold may also be a value pre-stored in the storage unit 26, etc.

[0045] The threshold setting unit 22 compares the density difference between two or more X-ray transmission images with the density difference between two or more other X-ray transmission images. In this embodiment, when one first background brightness is greater than another second background brightness and the first background brightness is less than the second background brightness, an arbitrary threshold is set based on the modified threshold (i.e., the search for the end threshold). Furthermore, when one first background brightness is less than another second background brightness and the first background brightness is greater than the second background brightness, an arbitrary threshold is set based on the value obtained by also performing correction by increasing the modified threshold (i.e., the search for the end threshold).

[0046] The inspection unit 23 inspects the article G based on the X-rays detected by the X-ray detection unit 7 after passing through it. The inspection unit 23 inspects the article G based on at least a portion of multiple images generated by the X-ray image generation unit 21. For example, the inspection unit 23 uses a differential image P3 to inspect the article G. It should be noted that the inspection unit 23 can also inspect the article G based on two or more images generated by the X-ray image generation unit 21. The inspection unit 23 checks the article G for foreign objects, cracks, etc., but is not limited to these. When the article G is wrapped in sheet-like packaging material, the inspection unit 23 can also check for damage to the packaging material, poor sealing (air leakage), etc. When the article G is contained in a package, the inspection unit 23 can perform foreign object confirmation checks, missing part confirmation checks, quantity confirmation checks, cavity confirmation checks, etc., within the package. The inspection unit 23 sends the inspection results of the article G to the judgment unit 24 and the storage unit 26.

[0047] Based on the inspection results received from the inspection unit 23, the determination unit 24 determines whether the item G is a qualified product. For example, the determination unit 24 determines whether there are foreign objects inside the item G, or whether the item G is broken. The determination unit 24 sends the determination result to the output unit 25 and the storage unit 26.

[0048] The output unit 25 outputs the determination result of the determination unit 24 to at least one of the parts other than the control unit 10 in the X-ray inspection apparatus 1, and to at least one of the devices different from the X-ray inspection apparatus 1. Thus, the X-ray inspection apparatus 1 and at least one of the devices different from the X-ray inspection apparatus 1 (e.g., a dispensing device located downstream of the X-ray inspection apparatus 1) can perform actions when the article G is a defective product. Other examples of the aforementioned devices different from the X-ray inspection apparatus 1 include, for example, an infeed conveyor 51, an outfeed conveyor 52, and a notification device.

[0049] The storage unit 26 records signals, data, etc. generated by the control unit 10. For example, the storage unit 26 records detection result signals sent from the X-ray detection unit 7, image data sent from the X-ray image generation unit 21, related data of arbitrary thresholds set by the threshold setting unit 22, related data of inspection results sent from the inspection unit 23, and related data of judgment results sent from the judgment unit 24.

[0050] Next, refer to Figure 6 and Figure 7 The adjustment method of the X-ray inspection apparatus 1 according to this embodiment will be described. The adjustment method of the X-ray inspection apparatus 1 is implemented to maintain or improve the inspection accuracy of the X-ray inspection apparatus 1, for example, in the calibration of the X-ray inspection apparatus 1. In the adjustment method of the X-ray inspection apparatus 1 described below, an arbitrary threshold is set for distinguishing the photon energy of the detected X-rays. Figure 6 and Figure 7 These are flowcharts illustrating the adjustment methods for X-ray inspection equipment.

[0051] like Figure 6 As shown, firstly, X-rays are irradiated into the examination chamber R (step S1, X-ray irradiation step). In step S1, the X-ray irradiation unit 6, located within the shielding box 4, is activated. Next, X-rays are detected by photon counting (step S2, X-ray detection step). In step S2, X-rays are detected by the X-ray detection unit 7 using photon counting. Next, the photon energy of the detected X-rays is distinguished into two or more energy regions based on an arbitrary threshold (step S3, distinction step). In step S3, using a predetermined initial threshold, the X-ray detection unit 7 distinguishes the photon energy into a first energy region and a second energy region.

[0052] Next, using photon energy, two or more X-ray transmission images corresponding to two or more energy regions are generated (step S4, image generation step). In step S4, a first set image is generated based on the X-ray detection result corresponding to the first energy region, and a second set image is generated based on the X-ray detection result corresponding to the second energy region.

[0053] Next, an arbitrary threshold is set based on the intensity differences between two or more X-ray transmission images (step S5, threshold setting step). In step S5, a threshold (provisional threshold) is set where the difference (brightness difference) between the background brightness of the first setting image and the background brightness of the first setting image is within a predetermined range. Furthermore, an arbitrary threshold is set by adding a correction value to the obtained provisional threshold. It should be noted that if the intensity difference between two or more X-ray transmission images is outside the predetermined range in step S5, the threshold change, discrimination step, image generation step, and threshold setting step are performed until the difference is within the predetermined range (i.e., steps S1 to S5 are repeated). In this case, it is also possible that: in step S3, photon energy is discriminated to two or more other energy regions based on other thresholds different from the arbitrary threshold; in step S4, two or more other X-ray transmission images corresponding to the other two or more energy regions are generated; and in step S5, the intensity difference between two or more X-ray transmission images is compared with the intensity difference between the other two or more X-ray transmission images.

[0054] Here, refer to Figure 7 The method for setting arbitrary thresholds is explained in detail. For example... Figure 6 As shown, it is determined whether the brightness difference is below a predetermined range (step S11). If the brightness difference is below the predetermined range (step S11: Yes), the threshold is corrected (step S12). An arbitrary threshold is thus set. It should be noted that the corrected threshold is equivalent to the threshold used in the most recent step S3 (e.g., the initial threshold).

[0055] On the other hand, if the brightness difference is outside the predetermined range (step S11: No), it is determined whether the first background brightness is greater than the second background brightness (step S13). If the first background brightness is greater than the second background brightness (step S13: Yes), it is determined whether the first background brightness of the previous first setting image (hereinafter referred to as "the previous first background brightness") is less than the second background brightness of the previous second setting image (hereinafter referred to as "the previous second background brightness") (step S14). If the previous first background brightness is less than the previous second background brightness (step S14: Yes), step S12 is performed. On the other hand, if the previous first background brightness is greater than the previous second background brightness (step S14: No), a threshold reduction correction is performed (step S15). In step S15, the initial threshold is reduced by a predetermined value to become another threshold. In addition, the process is restarted from step S1 using the other threshold. It should be noted that if the previous first background brightness and the previous second background brightness do not exist, step S14 is not performed, but step S15 is performed.

[0056] If the first background brightness is less than the second background brightness (step S13: No), a threshold increase correction is performed (step S16). In step S16, the initial threshold is increased by a predetermined value to become another threshold. Next, it is determined whether the previous first background brightness was greater than the previous second background brightness (step S17). If the previous first background brightness was greater than the previous second background brightness (step S17: Yes), step S12 is performed. On the other hand, if the previous first background brightness was less than the previous second background brightness (step S17: No), the process is restarted from step S1 using another threshold. It should be noted that if neither the previous first background brightness nor the previous second background brightness exists, step S17 is not performed, and step S1 is performed instead.

[0057] According to the X-ray inspection apparatus 1 and its adjustment method described above in this embodiment, the threshold setting unit 22 sets an arbitrary threshold based on the density difference between the first setting image and the second setting image. Therefore, for example, when the inspection conditions of the article G are changed, the arbitrary threshold may change. That is, the threshold setting unit 22 can set an appropriate threshold corresponding to changes in the inspection conditions, etc. As a result, even if the inspection conditions of the article G are changed, the article G can be inspected with excellent accuracy.

[0058] In this embodiment, the X-ray detection unit 7 can also distinguish photon energy into a first energy region, a second energy region, and a third energy region that is lower than the first and second energy regions. In this case, for example, by excluding the energy regions containing the most noise from the first to the third energy regions, the inspection accuracy of the article G can be improved.

[0059] In this embodiment, the arbitrary threshold is determined based on a provisional threshold where the difference in density between the first setting image and the second setting image is within a predetermined range. Therefore, it is easy to detect whether there are foreign objects or the like contained in the article G.

[0060] In this embodiment, the arbitrary threshold is the value obtained by adding a correction value to a provisional threshold. In this case, the inspection accuracy of item G can be improved.

[0061] In this embodiment, if the difference in intensity between the first setting image and the second setting image is outside a predetermined range, after the threshold setting unit 22 changes any threshold, the X-ray image generation unit 21 generates other first setting images and other second setting images corresponding to two or more other energy regions identified based on the changed threshold. The threshold setting unit 22 then determines whether the difference in intensity between the other first setting images and the other second setting images is within a predetermined range. In this case, the threshold setting unit 22 can accurately set any threshold within a predetermined range to ensure that the difference in intensity between the first setting image and the second setting image is within the predetermined range.

[0062] Alternatively, the X-ray image generation unit 21 generates other first-setting images and other second-setting images corresponding to two or more other energy regions identified based on other thresholds different from the arbitrary threshold. The threshold setting unit compares the density difference between the first-setting images and the second-setting images with the density difference between the other first-setting images and the other second-setting images. In this case, the threshold setting unit 22 can easily determine whether the arbitrary threshold is appropriate by comparing the differences mentioned above.

[0063] The embodiments of this disclosure have been described above. However, this disclosure is not necessarily limited to the embodiments described above, and various modifications can be made without departing from its spirit.

[0064] In the above embodiments, the X-ray detection unit distinguishes the photon energy of the detected X-rays into two or more energy regions based on an arbitrary threshold, but is not limited to this. Figure 8 This is a functional diagram of the control unit involved in the modified example. For example... Figure 8As shown, the control unit 10A includes an X-ray image generation unit 21, a threshold setting unit 22, an inspection unit 23, a judgment unit 24, an output unit 25, a storage unit 26, and a discrimination unit 27. The discrimination unit 27 is a part that distinguishes the photon energy of detected X-rays into two or more energy regions based on an arbitrary threshold. For example, the discrimination unit 27 can distinguish photon energy into a first energy region, a second energy region, and a third energy region. By using such a control unit 10A, the X-ray detection unit does not need to perform photon counting for each energy region. In other words, the X-ray detection unit only needs to output the X-ray detection result to the control unit 10A. This simplifies the configuration of the X-ray detection unit.

[0065] In the above embodiment, the X-ray inspection apparatus includes a control unit that performs image processing; however, it is not limited to this. For example, functions such as image processing, determining the presence or absence of foreign objects in an object based on differential images, and displaying X-ray inspection results may not be included in the X-ray inspection apparatus. Instead, these functions may be installed in a control device capable of communicating with the X-ray inspection apparatus via signal or wireless communication. In this case, an X-ray inspection system can be realized that includes an X-ray inspection apparatus and the control device into which the inspection results of the X-ray inspection apparatus are input. With such an X-ray inspection system, the same effects as in the above embodiment can be achieved. Furthermore, the configuration of the control unit included in the X-ray inspection apparatus can be simplified. Moreover, the user can check the inspection results even in a location far from the X-ray inspection apparatus. It should be noted that the control device is not particularly limited, but examples include laptops, tablets, etc. Furthermore, the control device may not include the function of determining the presence or absence of foreign objects.

Claims

1. An X-ray inspection device, comprising: The transport department transports goods. An X-ray source is used to irradiate the article with X-rays. The X-ray detection unit is capable of detecting X-rays by photon counting, and can distinguish the photon energy of the detected X-rays into two or more energy regions based on any threshold. The threshold setting unit sets the arbitrary threshold. The X-ray image generation unit generates two or more X-ray transmission images corresponding to the two or more energy regions based on the detection results of the X-ray detection unit. as well as The inspection department inspects the article based on the X-rays detected by the X-ray detection unit after they have passed through the article. The X-ray image generation unit generates a first setting image corresponding to the X-ray in one of the two or more energy regions, and a second setting image corresponding to the X-ray in the other of the two or more energy regions, as threshold setting images. The threshold setting unit sets the arbitrary threshold so that the difference between the background brightness of the first setting image and the background brightness of the second setting image in the two or more X-ray transmission images is within a predetermined range. The X-ray image generation unit generates a first transmission image and a second transmission image based on the set arbitrary threshold, and performs subtraction processing on the first transmission image and the second transmission image to generate a difference image. The inspection unit performs an inspection of the item based on the differential image.

2. The X-ray inspection apparatus according to claim 1, wherein, The X-ray detection unit identifies the photon energy into a first energy region, a second energy region, and a third energy region that is lower than the first and second energy regions.

3. An X-ray inspection device, comprising: The transport department transports goods. An X-ray source is used to irradiate the article with X-rays. An X-ray detection unit capable of detecting the X-rays by photon counting; and The control unit receives the detection results from the X-ray detection unit. The control unit has: The discrimination unit, based on an arbitrary threshold, distinguishes the photon energy of the X-rays detected by the X-ray detection unit into two or more energy regions; The threshold setting unit sets the arbitrary threshold. The X-ray image generation unit generates two or more X-ray transmission images corresponding to the two or more energy regions based on the detection results of the X-ray detection unit. as well as The inspection department inspects the article based on the X-rays transmitted through it, as detected by the X-ray detection unit. The X-ray image generation unit generates a first setting image corresponding to the X-ray in one of the two or more energy regions, and a second setting image corresponding to the X-ray in the other of the two or more energy regions, as threshold setting images. The threshold setting unit sets the arbitrary threshold so that the difference between the background brightness of the first setting image and the background brightness of the second setting image in the two or more X-ray transmission images is within a predetermined range. The X-ray image generation unit generates a first transmission image and a second transmission image based on the set arbitrary threshold, and performs subtraction processing on the first transmission image and the second transmission image to generate a difference image. The inspection unit performs an inspection of the item based on the differential image.

4. The X-ray inspection apparatus according to claim 3, wherein, The discrimination unit identifies the photon energy into a first energy region, a second energy region, and a third energy region that is lower than the first energy region and the second energy region.

5. The X-ray inspection apparatus according to any one of claims 1 to 4, wherein, The arbitrary threshold is the value obtained by adding a correction value to the threshold.

6. The X-ray inspection apparatus according to any one of claims 1 to 4, wherein, If the difference between the background brightness of the first setting image and the background brightness of the second setting image is outside a predetermined range, after the threshold setting unit changes the arbitrary threshold, The X-ray image generation unit generates two or more X-ray transmission images corresponding to two or more other energy regions identified based on the modified threshold. The threshold setting unit determines whether the difference between the background brightness of the other first setting image and the background brightness of the other second setting image in the other two or more X-ray transmission images is within a predetermined range.

7. The X-ray inspection apparatus according to any one of claims 1 to 4, wherein, The X-ray image generation unit generates two or more X-ray transmission images corresponding to two or more other energy regions identified based on other thresholds different from the arbitrary threshold. The threshold setting unit compares the difference between the background brightness of the first setting image and the background brightness of the second setting image with the difference between the background brightness of the other first setting images and the background brightness of the other second setting images in the other two or more X-ray transmission images.

8. A method for adjusting an X-ray inspection device, comprising: The X-ray irradiation procedure involves irradiating the examination chamber, which is set up in the frame, with X-rays. The X-ray detection step involves detecting the X-rays by photon counting. The identification step involves classifying the photon energy of the detected X-rays into two or more energy regions based on an arbitrary threshold. The image generation step involves using the photon energy to generate two or more X-ray transmission images corresponding to the two or more energy regions. as well as The threshold setting step involves setting an arbitrary threshold such that the difference between the background brightness of the first setting image and the background brightness of the second setting image in the two or more X-ray transmission images is within a predetermined range. The first setting image is an image corresponding to the X-rays of one of the two or more energy regions, and the second setting image is an image corresponding to the X-rays of another energy region in the two or more energy regions.

9. The adjustment method of the X-ray inspection device according to claim 8, wherein, If the difference between the background brightness of the first setting image and the background brightness of the second setting image is outside a predetermined range in the threshold setting step, the arbitrary threshold change, the discrimination step, the image generation step, and the threshold setting step are performed until the difference is within the predetermined range.

10. The adjustment method of the X-ray inspection apparatus according to claim 8, wherein, In the discrimination step, the photon energy is discriminated into two or more other energy regions based on other thresholds that are different from the arbitrary threshold. In the image generation step, two or more X-ray transmission images corresponding to the other two or more energy regions are generated. In the threshold setting step, the difference between the background brightness of the first setting image and the background brightness of the second setting image is compared with the difference between the background brightness of the other first setting images and the background brightness of the other second setting images in the other two or more X-ray transmission images.

Images