Computed tomography system

Abstract

To provide means that, when inspecting whether or not a detection object is included in an inspection object by using a computer tomographic image, increases the throughput of the inspection compared to a prior art.SOLUTION: A computer tomography system 1 comprises a table 161 that moves up and down and rotates around a vertical axis. When receiving hand baggage P from a conveyor 17, the table 161 moves down to a height at which the hand baggage P is located in front of an X-ray irradiation unit 14, and subsequently rotates around the vertical axis by a predetermined angle. The X-ray irradiation unit 14 and a panel sensor 15 photograph X-ray transmission images of the rotated hand baggage P. While the rotation and photographing of the hand baggage P are repeated, the photographed X-ray transmission images are sequentially displayed by a terminal device 10. The terminal device 10 creates a computer tomography image from the plurality of X-ray transmission images. However, when an inspector sees the X-ray transmission images and finds a dangerous material and performs a predetermined operation on the terminal device 10, the computer tomography system 1 suspends the processing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for inspecting an object to be inspected, such as baggage, using an X-ray transmission image. [Background technology]

[0002] There is a computer tomography system that uses X-ray transmission images taken from multiple directions by changing the relative positions of the X-ray device and the object being examined (including a person) to generate a computed tomography (CT) image that shows the three-dimensional shape of the object.

[0003] Meanwhile, a method of inspecting whether or not an object to be inspected, such as baggage, contains a detection target, such as a blade, is becoming widespread, using an X-ray transmission image of the object taken by an X-ray imaging device.

[0004] Even if an object to be detected, such as a blade, is contained within an object to be inspected, such as baggage, the shape of the object may not be recognizable in the X-ray image depending on the shape of the object and its orientation within the object. As a result, the object may be overlooked during inspection.

[0005] To solve the above problem, a method has been proposed in which a computed tomography system is used to generate a computed tomography image of an object to be inspected, and the generated computed tomography image is used to inspect whether the object to be detected is contained within the object to be inspected.

[0006] For example, Patent Document 1 proposes an X-ray inspection device that, when photographing an object to be inspected from multiple directions using X-rays, identifies the relative positional relationship between the object to be inspected and the X-ray imaging device for each photograph, and generates a computed tomographic image using the multiple X-ray transmission images taken based on the identified positional relationship. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-223468 Summary of the Invention [Problem to be solved by the invention]

[0008] Generating a computed tomography image requires taking multiple X-ray transmission images and then processing them to synthesize a three-dimensional computed tomography image, which takes much more time than taking a single X-ray transmission image.

[0009] Therefore, for example, when inspecting the baggage of passersby, using computed tomography images can significantly reduce inspection throughput compared to inspecting each piece of baggage using a single X-ray image, which can lead to inconveniences such as long lines of passersby waiting for inspection.

[0010] In view of the above circumstances, the present invention provides a means for increasing the throughput of inspection compared to the prior art when inspecting whether an object to be inspected contains a detection object using a computed tomographic image. [Means for solving the problem]

[0011] The present invention generates a computed tomographic image using a plurality of X-ray transmission images taken by an X-ray imaging device while changing the relative position of the object to be inspected and the X-ray imaging device around a vertical axis, While taking the multiple X-ray images in sequence, As a first aspect, a computed tomography system is proposed that stops processing for generating a computed tomography image when a detection target object within an inspection object is detected based on any of the captured X-ray transmission images.

[0012] According to the computed tomography system of the first aspect, when a detection object within an object to be inspected is detected based on one of multiple X-ray transmission images taken to generate a computed tomography image, the inspection can be completed without generating a computed tomography image for that object to be inspected, thereby increasing the inspection throughput compared to conventional technology which requires the generation of a computed tomography image for each object to be inspected.

[0013] In the computed tomography system according to the first aspect described above, a second aspect may be adopted in which the captured X-ray transmission image is displayed and the processing for generating the computed tomography image is stopped in response to an operation by a user who views the X-ray transmission image.

[0014] According to the computed tomography system of the second aspect, the user can determine whether or not the object to be detected is contained within the object to be inspected by looking at the displayed X-ray transmission image, and if it is determined that the object to be detected is contained within the object to be inspected, the user can perform a specified operation to stop the subsequent processing for generating the computed tomography image, thereby shortening the time required for the inspection.

[0015] In the computed tomography system according to the second aspect, a configuration may be adopted as a third aspect in which the X-ray transmission images are displayed sequentially so that the angular difference between the relative positions around the vertical axis when adjacent X-ray transmission images were captured in the display order becomes gradually smaller.

[0016] According to the computed tomography system of the third aspect, when the object to be detected is contained within the object to be inspected, the probability that an X-ray transmission image showing the shape of the object to be detected in a recognizable form will be displayed at an early stage is increased, compared to when X-ray transmission images taken from different directions at equal angular intervals are displayed sequentially, thereby reducing the time required for the inspection.

[0017] In the computed tomography system according to the first aspect described above, a configuration may be adopted as a fourth aspect in which, when an object to be detected is image-recognized from the captured X-ray transmission image, processing for generating a computed tomography image is stopped.

[0018] According to the computed tomography system of the fourth aspect, whether or not the detection target is captured in the X-ray transmission image is determined by the computed tomography system, eliminating the need for the user to make that determination.

[0019] In the computed tomography system according to the fourth aspect described above, a configuration may be adopted as a fifth aspect in which image recognition of the object to be detected is attempted sequentially from the X-ray transmission images so that the angular difference in the relative positions around the vertical axis when adjacent X-ray transmission images are taken in the order in which image recognition is performed becomes gradually smaller.

[0020] According to the computed tomography system of the fifth aspect, when a detection object is contained within an object to be inspected, the probability of the detection object being recognized at an early stage is increased, compared to when X-ray transmission images taken from different directions at equal angular intervals are sequentially recognized, thereby reducing the time required for inspection.

[0021] In the computed tomography system according to the third or fifth aspect, a sixth aspect may be adopted in which the X-ray imaging device captures X-ray transmission images by scanning using a line sensor, and the X-ray imaging device sequentially captures X-ray transmission images so that the angular difference of the relative position around the vertical axis when capturing the X-ray transmission images in the order of capture becomes gradually smaller.

[0022] According to the computed tomography system of the sixth aspect, a line sensor is used, which is cheaper than a panel sensor but takes a long time to capture an X-ray transmission image. However, if an object to be detected is found in the X-ray transmission image, the inspection is terminated without taking any further X-ray transmission images, which significantly reduces the time required for the inspection.

[0023] In the computed tomography system according to any one of the first to sixth aspects, The angular difference around the vertical axis between the shooting directions of two adjacent X-ray radiographs taken to generate a computed tomographic image may be adopted as a seventh aspect.

[0024] According to the computed tomography system of the seventh aspect, the computed tomography system can be configured to perform various functions depending on the situation in which the computed tomography system is used (such as the waiting status of passersby, the required accuracy of the examination, etc.). The angular difference around the vertical axis between the shooting directions of two adjacent X-ray radiographs taken to generate a computed tomographic image Since the throughput can be changed, inspections can be performed at a desirable throughput depending on the situation. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram showing the overall configuration of a computed tomography system according to an embodiment; [Figure 2] 1A and 1B are diagrams for explaining the behavior of a computed tomography system according to an embodiment; [Figure 3] 1A and 1B are diagrams for explaining the behavior of a computed tomography system according to an embodiment; [Figure 4] 1A and 1B are diagrams for explaining the behavior of a computed tomography system according to an embodiment; [Figure 5] FIG. 2 is a block diagram showing the functional configuration of a terminal device according to an embodiment. [Figure 6] FIG. 10 is a diagram illustrating a screen displayed by a terminal device according to an embodiment. [Figure 7] 10A and 10B are diagrams illustrating how the relative positions of baggage and an X-ray imaging device in the vertical direction are changed in a computed tomography system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0026] [Embodiment] A computer tomography system 1 according to one embodiment of the present invention will be described below. Fig. 1 is a diagram showing the overall configuration of the computer tomography system 1. However, Fig. 1 also shows components that are not actually visible from the outside, such as those located inside the housing 11, inside the wall covering the bottom of the conveyors 17 and 18, and on the other side of the housing 11.

[0027] The housing 11 is a box-shaped member that houses the X-ray imaging device, and is covered on the inside with, for example, lead so that the X-rays emitted by the X-ray imaging device do not leak out.

[0028] An opening serving as an entrance for baggage P (an example of an object to be inspected) is provided in the side wall of housing 11 on the upstream side (left side in FIG. 1 ) of housing 11. Lead curtain 12 is attached to housing 11 so as to hang down from the upper edge of the opening to block this entrance. Lead curtain 12 is made up of multiple strips of rubber containing lead, and like a noren curtain, it bends to allow baggage P to move from outside housing 11 toward inside housing 11, and returns to its original shape to block the entrance after baggage P has passed through the entrance of housing 11. Lead curtain 12 reduces the amount of X-rays that leak out from the entrance of housing 11 when an X-ray imaging device irradiates X-rays inside housing 11.

[0029] Furthermore, housing 11 has an opening on the side wall on the downstream side (right side in FIG. 1 ) of housing 11, which serves as an exit for baggage P. Lead curtain 13 is attached to housing 11 so as to hang down from the upper edge of the opening to block this exit. Lead curtain 13 has the same structure as lead curtain 12; it bends to allow baggage P to move from inside housing 11 to outside housing 11, and returns to its original shape after baggage P has passed through the exit of housing 11, blocking the exit. Lead curtain 13 reduces the amount of X-rays that leak out from the exit of housing 11 when the X-ray imaging device irradiates X-rays inside housing 11.

[0030] An X-ray irradiator 14 and a panel sensor 15, which constitute the X-ray imaging device, are disposed within the housing 11. The X-ray irradiator 14 is disposed, for example, on the inner surface below the entrance of the side wall on the upstream side of the housing 11, and irradiates X-rays that spread, for example, in a conical shape, toward the panel sensor 15. The panel sensor 15 is disposed, for example, on the inner surface below the exit of the side wall on the downstream side of the housing 11, and has a large number of light-receiving elements arranged in a plane, and these light-receiving elements measure the intensity of the X-rays that have been irradiated from the X-ray irradiator 14 and transmitted through the baggage P, thereby generating a signal representing an X-ray transmission image.

[0031] The X-ray irradiation unit 14 and the panel sensor 15 may be arranged in any manner as long as the X-rays emitted by the X-ray irradiation unit 14 are directed toward the baggage P that has been moved to the shooting position by the lifting and rotating device 16, as described below, and the X-rays that have passed through the baggage P are directed toward the panel sensor 15.

[0032] The lifting and rotating device 16 is a device that lifts and lowers baggage P that has entered the housing 11 and rotates it about a vertical axis. The lifting and rotating device 16 includes a table 161, which is a disk-shaped member on which the baggage P rests, a plurality of rollers 162 that are provided so that the baggage P can easily move on the upper surface of the table 161 due to gravity, and a stopper 163 that is arranged near the outer edge of the table 161. The lifting and rotating device 16 can perform the following operations. (1) Raising and lowering the table 161 (2) Rotating the table 161 around the vertical axis (3) Rotating the table 161 around the horizontal axis and tilting the top surface of the table 161 relative to the horizontal plane. (4) Movement of the stopper 163 into and out of the table 161

[0033] The stopper 163 is disposed near the outer edge located on the lower side when the table 161 rotates around the horizontal axis and the upper surface is tilted relative to the horizontal plane. The role of the lifting and rotating device 16 that performs the above-mentioned operations will be described later.

[0034] Conveyor 17 is a device disposed on the upstream side of housing 11 and transports baggage P toward housing 11. Conveyor 18 is a device disposed on the downstream side of housing 11 and transports baggage P discharged from housing 11 downstream.

[0035] The controller 19 is a data processing device that controls the operations of the X-ray irradiation unit 14, the panel sensor 15, the lifting and rotating device 16, the conveyor 17, and the conveyor 18. The behavior of the X-ray irradiation unit 14, the panel sensor 15, the lifting and rotating device 16, the conveyor 17, and the conveyor 18 that operate under the control of the controller 19 will be described later.

[0036] The controller 19 performs wired or wireless data communication with the terminal device 10. The controller 19 generates X-ray transmission image data representing an X-ray transmission image using a signal generated by the panel sensor 15, and transmits the generated X-ray transmission image data to the terminal device 10. Furthermore, the controller 19 receives, depending on the situation, from the terminal device 10, stop instruction data (described later) instructing to stop the process for capturing an X-ray transmission image, restart instruction data (described later) instructing to restart the stopped process for capturing an X-ray transmission image, and end instruction data (described later) instructing to end the process for capturing an X-ray transmission image.

[0037] The terminal device 10 is a computer used by an inspector. The terminal device 10 is equipped with a memory for storing various data, a processor for processing various data in accordance with programs stored in the memory, a communication interface for communicating data with the controller 19, a display for displaying screens containing various information to the user, and input devices such as a keyboard for accepting user operations on the terminal device 10. The display and input devices of the terminal device 10 may be built into the main body, or may be external devices connected to an input / output interface of the main body.

[0038] Figures 2, 3 and 4 are diagrams for explaining the behavior of the X-ray irradiation unit 14, panel sensor 15, lifting and rotating device 16, conveyor 17 and conveyor 18 (hereinafter referred to as the behavior of the computed tomography system 1), which operate under the control of the controller 19.

[0039] 2 shows the behavior of the computed tomography system 1 when it moves baggage P placed on the upstream side of the conveyor 17 onto the table 161 of the elevator / rotator 16. FIG. 2(A) shows a state in which baggage P is being transported by the conveyor 17 toward the housing 11. In this state, the table 161 is tilted downward toward the downstream side at a height such that the upstream edge of its upper surface is slightly lower than the upper surface of the conveyor 17. In addition, a stopper 163 protrudes upward on the downstream side of the table 161. After the baggage P moves into the housing 11 by the conveyor 17, it moves on the rollers 162 due to gravity and hits the stopper 163, stopping on the table 161. FIG. 2(B) shows a state in which the baggage P has stopped on the table 161.

[0040] Thereafter, table 161 rotates slightly around the horizontal axis, and the top surface becomes horizontal. Then, stopper 163 retracts into table 161. As a result, baggage P is placed on table 161, which is horizontal, as shown in FIG. 2(C).

[0041] 3 shows the behavior of the computed tomography system 1 when capturing an X-ray transmission image of baggage P. As shown in FIG. 3(A), the table 161 descends so that the baggage P is positioned in front of the X-ray irradiation unit 14. Then, as shown in FIG. 3(B), the X-ray irradiation unit 14 and the panel sensor 15 capture an X-ray transmission image of the baggage P. The captured X-ray transmission image is immediately displayed on the terminal device 10 (described later).

[0042] Next, as shown in Fig. 3(C), while the X-ray irradiation unit 14 stops emitting X-rays, the table 161 rotates by a predetermined angle around the vertical axis. After that, the capturing of the X-ray transmission images shown in Fig. 3(B) and the rotation of the table 161 are repeated, and X-ray transmission images of the baggage P captured from a plurality of different angles are displayed sequentially on the terminal device 10.

[0043] In this embodiment, the table 161 is rotated around the vertical axis so that the rotation angle around the vertical axis (the angular difference between the relative positions of the baggage P and the X-ray imaging device) when capturing adjacent X-ray transmission images in the order of imaging by the X-ray irradiation unit 14 and the panel sensor 15, i.e., the order of display by the terminal device 10, gradually decreases.

[0044] For example, if the position of table 161 around the vertical axis when the first X-ray transmission image is taken is the reference position (0 degrees), the X-ray transmission images are taken sequentially at positions where table 161 has rotated around the vertical axis (for example, clockwise when viewed from above) by the following angles.

[0045] (1) First Stage 1st: 0 degrees, 2nd: 30 degrees, 3rd: 60 degrees, 4th: 90 degrees (2) Second Stage 5th: 110 degrees, 6th: 130 degrees, 7th: 150 degrees, 8th: 170 degrees, 9th: 190 degrees (3) Third stage: 10th sheet: 200 degrees, 11th sheet: 210 degrees, 12th sheet: 220 degrees, 13th sheet: 230 degrees, 14th sheet: 240 degrees, 15th sheet: 250 degrees, 16th sheet: 260 degrees, 17th sheet: 270 degrees, 18th sheet: 280 degrees, 19th sheet: 290 degrees, 20th sheet: 300 degrees, 21st sheet: 310 degrees, 22nd sheet: 320 degrees, 23rd sheet: 330 degrees, 24th sheet: 340 degrees, 25th sheet: 350 degrees (4) 4th stage: 26th: 10 degrees, 27th: 20 degrees, 28th: ​​40 degrees, 29th: 50 degrees, 30th: 70 degrees, 31st: 80 degrees, 32nd: 100 degrees, 33rd: 120 degrees, 34th: 140 degrees, 35th: 160 degrees, 36th: 180 degrees

[0046] The above-mentioned (1) first stage is a stage in which the table 161 is rotated 30 degrees around the vertical axis to capture an X-ray transmission image.

[0047] The second stage (2) above is a stage in which the table 161 is rotated 20 degrees around the vertical axis to capture an X-ray transmission image.

[0048] The third stage (3) above is a stage in which the table 161 is rotated 10 degrees around the vertical axis to capture an X-ray transmission image.

[0049] The fourth stage (4) is a stage in which X-ray images are taken at angles that have not yet been taken in the first to third stages, among the X-ray images rotated by 10 degrees from the reference position.

[0050] When all 36 X-ray transmission images have been taken, or when an inspector who has looked at the X-ray transmission images displayed by the terminal device 10 determines that a detection object such as a blade is visible in the X-ray transmission image and performs an operation such as clicking an "End" button (described later) on the terminal device 10, the table 161 rotates around the vertical axis to the reference position and then rises so that its upper surface is slightly higher than the upper surface of the conveyor 18, as shown in Figure 3(D).

[0051] 4 shows the behavior of the computed tomography system 1 when it moves baggage P placed on table 161 inside the housing 11 toward the downstream side of the conveyor 18. First, as shown in FIG. 4(A), the table 161 rotates slightly around the horizontal axis, and the upper surface is tilted downward toward the downstream side. As a result, the baggage P moves from the table 161 toward the conveyor 18 due to gravity.

[0052] 4(B), the conveyor 18 transports the baggage P downstream. Meanwhile, the table 161 moves slightly downward while maintaining its inclination in preparation for receiving the next baggage. In addition, the stopper 163 protrudes upward from the table 161.

[0053] The above is a description of the behavior of the X-ray irradiation unit 14, panel sensor 15, elevator / rotation device 16, conveyor 17, and conveyor 18, which operate under the control of the controller 19.

[0054] Fig. 5 is a block diagram showing the functional configuration of the terminal device 10. That is, when the processor of the terminal device 10 performs data processing in accordance with the program according to this embodiment, the terminal device 10 functions as a device having the components shown in Fig. 5. The functional configuration of the terminal device 10 will be described below.

[0055] The X-ray transmission image acquisition unit 121 receives X-ray transmission image data from the controller 19. The computed tomographic image generation unit 122 generates a computed tomographic image using 36 X-ray transmission images representing the X-ray transmission image data that the X-ray transmission image acquisition unit 121 received from the controller 19.

[0056] The image recognition unit 123 recognizes the detected object, such as a blade, from each of the X-ray transmission images represented by the X-ray transmission image data received by the X-ray transmission image acquisition unit 121 and the computed tomography images generated by the computed tomography image generation unit 122.

[0057] Note that various known image recognition methods may be employed as a method by which the image recognition unit 123 recognizes the detection target from the image. For example, a machine learning model may be constructed using training data in which an X-ray transmission image of the detection target is used as an explanatory variable and a determination result that "it is a detection target" is used as an objective variable. An image represented by the X-ray transmission image data received by the X-ray transmission image acquisition unit 121 may be input as an explanatory variable to the machine learning model, which is constructed using training data in which a computer tomography ... computer tomography image generated by the computer tomography image generation unit 122 may be input as an explanatory variable to the machine learning model, which is constructed using training data in which a computer tomography image of the detection target is used as an explanatory variable. An image represented by the computer tomography image generated by the computer tomography image generation unit 122 may be input as an explanatory variable to the machine learning model, which is constructed using training data in which a computer tomography image of the detection target is used as an explanatory variable. An image represented by the computer tomography image generated by the computer tomography image generation unit 122 may be input as an explanatory variable to the machine learning model, which is constructed using training data in which a computer tomography image of the detection target is used as an explanatory variable. The probability that the image contains an image of the detection target may be output as a determination result.

[0058] The display unit 124 displays to the inspector a screen (hereinafter referred to as the image display screen) containing information such as the image represented by the X-ray transmission image data received by the X-ray transmission image acquisition unit 121, the image generated by the computed tomography image generation unit 122, and the judgment results by the image recognition unit 123.

[0059] 6A and 6B are diagrams illustrating example image display screens. FIG. 6A illustrates an example image display screen displayed by the display unit 124 immediately after the first X-ray transmission image of the baggage currently being inspected is captured. In area A1 of the image display screen, the last X-ray transmission image and computed tomography image captured of the baggage are displayed in a large size. In area A2 of the image display screen, all X-ray transmission images and computed tomography images already captured of the baggage are displayed in a small size. By clicking on any of the images displayed in area A2, the inspector can have the clicked image displayed in a large size in area A1 instead of the last X-ray transmission image or computed tomography image captured.

[0060] In area A3 of the image display screen, if an inspector looks at the image displayed in area A1 or A2 and determines that either image contains a detection target such as a blade, an "End" button will be displayed to end the series of processes for the currently inspected baggage without performing any further processing to generate a computed tomographic image (including processing to take an X-ray image).

[0061] FIG. 6B illustrates an example of an image display screen displayed by the display unit 124 immediately after the first X-ray transmission image is captured.

[0062] 6(C) shows an example of an image display screen displayed by the display unit 124 immediately after all 36 X-ray transmission images have been captured. In area A4 of the image display screen in FIG. 6(C), a message such as "A computed tomographic image is being generated" is displayed.

[0063] Fig. 6(D) shows an example of an image display screen displayed by the display unit 124 after a computed tomographic image has been generated. The computed tomographic image generated by the computed tomographic image generation unit 122 is displayed in area A1 of Fig. 6(D). The examiner can rotate the computed tomographic image displayed in area A1 by dragging it up, down, left, or right with the cursor, for example, to check the three-dimensional shape of the object shown in the computed tomographic image from a desired direction.

[0064] FIG. 6(E) illustrates an example of an image display screen that the display unit 124 displays when the image recognition unit 123 determines that the X-ray transmission image contains an image of the detection object with a probability equal to or greater than a predetermined threshold (e.g., a probability of 50% or greater). An X-ray transmission image determined to contain an image of the detection object with a probability equal to or greater than the threshold is displayed in an area A1 of this image display screen. Furthermore, in the image displayed in the area A1, the area containing the detection object is displayed in a manner that distinguishes it from other areas. In the example of FIG. 6(E), the area containing the detection object is distinguished from other areas by being surrounded by a dashed rectangle. The display manner for distinguishing the area containing the detection object from other areas is not limited to this. For example, an area containing the detection object may be displayed in a color different from other areas, or only the area containing the detection object may be displayed in a flashing color.

[0065] Furthermore, in area A4 of the image display screen in FIG. 6(E), a message such as "Dangerous object detected" is displayed. When this image display screen is displayed, that is, when the image recognition unit 123 determines that the X-ray transmission image contains an image of the detection object with a probability equal to or greater than a threshold, the transmission unit 126 (described later) of the terminal device 10 transmits stop instruction data to the controller 19 to instruct the controller 19 to stop the process of capturing the X-ray transmission image. In response to this stop instruction data, the X-ray irradiation unit 14 and the like stop the process of capturing the X-ray transmission image under the control of the controller 19. Therefore, in area A3 of the image display screen in FIG. 6(E), in addition to the "End" button, a "Resume" button for instructing the controller 19 to resume the process of capturing the X-ray transmission image that has been stopped is displayed.

[0066] Fig. 6(F) illustrates an example of an image display screen that is displayed by the display unit 124 when the image recognition unit 123 determines that the image of the detection object is included in the computed tomographic image with a probability equal to or higher than a predetermined threshold (for example, a probability of 50% or higher). The image display screen of Fig. 6(F) is similar to the image display screen of Fig. 6(E) except that the image displayed in area A1 is a computed tomographic image rather than an X-ray transmission image. This concludes the description of the image display screen that is displayed by the display unit 124.

[0067] The functional configuration of the terminal device 10 will be further described with reference to Fig. 5. The operation reception unit 125 receives operations by the inspector on the image display screen (for example, operations such as clicking on a button displayed in area A3). The transmission unit 126 transmits stop instruction data, restart instruction data, end instruction data, etc. to the controller 19 in accordance with the inspector's operations received by the operation reception unit 125. This concludes the description of the functional configuration of the terminal device 10.

[0068] When an inspector looks at the X-ray transmission image or computed tomography image displayed on the image display screen (FIG. 6) and finds an object that appears to be a detection target, the inspector clicks the "End" button or the like to cause the computed tomography system 1 to end the series of processes for the baggage currently being inspected. The inspector then opens the baggage being transported downstream on the conveyor 18 and checks whether the baggage contains the detection target.

[0069] On the other hand, if the inspector does not find any object that appears to be the target of detection in any of the 36 X-ray images and CT images displayed on the image display screen, he or she can click the "End" button or the like to cause the CT system 1 to end the series of processes for the baggage currently being inspected. In this case, the inspector will not do anything to the baggage being transported downstream on the conveyor 18.

[0070] Furthermore, if the image recognition unit 123 determines that the X-ray transmission image or the computed tomography image contains an image of the detection object with a probability equal to or greater than a threshold, the inspector looks at the X-ray transmission image or the computed tomography image displayed on the image display screen (FIGS. 6(E) and 6(F)) and determines whether the determination by the image recognition unit 123 is correct. If the inspector determines that the determination by the image recognition unit 123 is incorrect, the inspector clicks a "resume" button or the like to cause the computed tomography system 1 to resume the processing for the currently inspected baggage that has been stopped. On the other hand, if the inspector determines that the determination by the image recognition unit 123 is correct, the inspector clicks an "end" button or the like to cause the computed tomography system 1 to end the series of processing for the currently inspected baggage. Thereafter, the inspector opens the baggage being transported downstream on the conveyor 18 and checks whether the detection object is contained in the baggage.

[0071] As described above, once the inspector has completed the inspection of the current baggage to be inspected, he or she moves on to the inspection of the next baggage.

[0072] According to the above-described computed tomography system 1, if an inspector determines that a detection target is captured in any of a plurality of X-ray transmission images taken sequentially at different angles to generate a computed tomography image, the series of processes for generating a computed tomography image are terminated without executing any unexecuted processes (the process of capturing an uncaptured X-ray transmission image and the process of generating a computed tomography image). Therefore, the time required for inspection is shortened compared to when an inspector determines whether or not a detection target is contained in baggage based on a computed tomography image after the generation of the computed tomography image is completed.

[0073] Furthermore, according to the above-described computed tomography system 1, when an image of a detection object is included in an X-ray transmission image or a computed tomography image, the detection object is detected by the image recognition unit 123. This reduces the risk that the detection object will be overlooked by an inspector.

[0074] Furthermore, according to the above-described computed tomography system 1, the rotation angle of the baggage when capturing the X-ray transmission images is initially large and then changed to a smaller angle. Therefore, if the baggage contains a detection target, the detection target is likely to appear in a recognizable shape in the first few X-ray transmission images, and the time required for inspection is further reduced compared to when the baggage is rotated at a fixed rotation angle.

[0075] [Variations] The above-described embodiment may be modified in various ways within the scope of the technical concept of the present invention. These modifications are shown below. Note that two or more of the modifications shown below may be combined as appropriate.

[0076] (1) In the above-described embodiment, P held by the hand rotates by rotating the table 161 in order to change the angle at which the X-ray imaging device (X-ray irradiation unit 14 and panel sensor 15) images the baggage. However, the method of changing the relative positions of the baggage and the X-ray imaging device to change the angle at which the X-ray imaging device images the baggage is not limited to this. For example, the baggage may not rotate, but the X-ray imaging device may rotate around the baggage.

[0077] (2) In the above-described embodiment, the X-ray imaging device is equipped with a panel sensor. However, a line sensor may be used instead of the panel sensor. When a line sensor is used, the relative positions of the baggage and the X-ray imaging device in the vertical direction must be continuously changed during X-ray irradiation in order to capture a two-dimensional X-ray transmission image. Figure 7 is a diagram illustrating how the relative positions of the baggage and the X-ray imaging device in the vertical direction are changed in a computed tomography system 1 according to this modification.

[0078] In the example of Fig. 7(A), a line sensor 25 is disposed in place of the panel sensor 15 at a position opposite to the X-ray irradiation unit 14. Then, while X-rays are being irradiated from the X-ray irradiation unit 14, a table 161 moves up or down. As the table 161 moves vertically, the line sensor 25 sequentially receives X-rays that have passed through different positions in the vertical direction of the baggage P. As a result, the entire baggage P is scanned with X-rays, and a two-dimensional X-ray transmission image is generated.

[0079] 7(B), a line sensor 25 is disposed in place of the panel sensor 15 at a position facing the X-ray irradiator 14. However, the computed tomography system 1 according to this modification includes a transport unit 26 that transports the line sensor 25 in the vertical direction. While the X-ray irradiator 14 irradiates X-rays, the table 161 remains stationary in front of the X-ray irradiator 14, but the transport unit 26 raises or lowers the line sensor 25. As the line sensor 25 moves vertically, the line sensor 25 sequentially receives X-rays that have passed through different positions in the vertical direction of the baggage P. As a result, the entire baggage P is scanned with X-rays, and a two-dimensional X-ray transmission image is generated.

[0080] (3) The rotation angle and order of the table 161 for capturing multiple X-ray transmission images shown in the above embodiment are merely examples and may be changed in various ways. For example, the baggage P may be rotated around the vertical axis at the following angles in order, and images may be captured by the X-ray imaging device.

[0081] 1st: 0 degrees, 2nd: 90 degrees, 3rd: 180 degrees, 4th: 270 degrees, 5th: 30 degrees, 6th: 60 degrees, 7th: 120 degrees, 8th: 150 degrees, 9th: 210 degrees, 10th: 240 degrees, 11th: 300 degrees, 12th: 330 degrees, 13th: 10 degrees, 14th: 20 degrees, 15th: 40 degrees, 16th: 50 degrees, 17th: 70 degrees, 18th: 80 degrees, 19th: 100 degrees , 20th: 110 degrees, 21st: 130 degrees, 22nd: 140 degrees, 23rd: 160 degrees, 24th: 170 degrees, 25th: 190 degrees, 26th: 200 degrees, 27th: 220 degrees, 28th: ​​230 degrees, 29th: 250 degrees, 30th: 260 degrees, 31st: 280 degrees, 32nd: 290 degrees, 33rd: 310 degrees, 34th: 320 degrees, 35th: 340 degrees, 36th: 350 degrees (4) In the above-described embodiment ,Ko The angular difference around the vertical axis between the shooting directions of two adjacent X-ray transmission images taken to generate a computer tomographic image was set to 10 degrees. The angular difference around the vertical axis between the shooting directions of two adjacent X-ray radiographs taken to generate a computed tomographic image is not limited to 10 degrees. In addition, depending on the situation in which the computed tomography system 1 is used (required accuracy of computed tomography images, required throughput of inspection, etc.), for example, depending on the setting work of an inspector, etc. The angular difference around the vertical axis between the shooting directions of two adjacent X-ray radiographs taken to generate a computed tomographic image may be changeable.

[0082] (5) Some of the components that are included in the terminal device 10 in the above-described embodiment may be included in the controller 19 instead of the terminal device 10. For example, the controller 19 may include the computed tomography image generation unit 122 and the image recognition unit 123. In this case, the terminal device 10 may receive data indicating the results of the image recognition performed in the controller 19 and image data representing the computed tomography image generated in the controller 19 from the controller 19, and display the image display screen using these data.

[0083] (6) In the above-described embodiment, the series of processes for generating a computed tomography image by the computed tomography system 1 is terminated when the inspector performs an operation such as clicking an “End” button. In addition to this, or instead, when the image recognition unit 123 recognizes a detection target from an X-ray transmission image or a computed tomography image, the series of processes for generating a computed tomography image by the computed tomography system 1 may be terminated without the operation of the inspector.

[0084] (7) In the above-described embodiment, the X-ray image and the computed tomography image are displayed on the terminal device 10. However, the terminal device 10 may be configured to display the recognition result of the object to be detected by the image recognition unit 123 but not to display the X-ray image and the computed tomography image. If the accuracy of the detection of the object to be detected by the image recognition unit 123 is sufficiently high, the inspector will only need to determine whether or not it is necessary to open the baggage and check the contents based on the recognition result of the image recognition unit 123, and there is no need to display the images to the inspector.

[0085] (8) In the above-described embodiment, the movement of baggage from conveyor 17 to table 161 and the movement of baggage from table 161 to conveyor 18 are achieved by tilting table 161 relative to the horizontal. The method of moving baggage from conveyor 17 to table 161 and from table 161 to conveyor 18 is not limited to this. For example, instead of rollers 162 being driven rollers, rollers that are driven to rotate by a motor or the like may be used to transport baggage on table 161. Furthermore, a mechanism for pushing baggage from conveyor 17 into housing 11 using an arm or the like may be provided near the entrance of housing 11, or a mechanism for pushing baggage from inside housing 11 to conveyor 18 using an arm or the like may be provided near the exit of housing 11. [Explanation of symbols]

[0086] 1...Computed tomography system, 10...Terminal device, 11...Housing, 12...Lead curtain, 13...Lead curtain, 14...X-ray irradiation unit, 15...Panel sensor, 16...Lifting and rotating device, 17...Conveyor, 18...Conveyor, 19...Controller, 25...Line sensor, 26...Transport unit, 121...X-ray transmission image acquisition unit, 122...Computed tomography image generation unit, 123...Image recognition unit, 124...Display unit, 125...Operation reception unit, 126...Transmission unit, 161...Table, 162...Roller, 163...Stopper

Claims

1. A computed tomography system that generates a computed tomography image using a plurality of X-ray transmission images taken by an X-ray imaging device while changing the relative position of the object to be inspected and the X-ray imaging device around a vertical axis, and that stops processing to generate the computed tomography image if a detection object within the object to be inspected is detected based on any of the X-ray transmission images while the plurality of X-ray transmission images are being sequentially taken.

2. The captured X-ray transmission image is displayed, and the process for generating the computed tomographic image is stopped in response to an operation by a user who has viewed the X-ray transmission image. The computed tomography system of claim 1 .

3. The X-ray transmission images are sequentially displayed so that the angular difference between the relative positions of the X-ray transmission images adjacent to each other in the display order around the vertical axis at the time of capturing the images becomes smaller in a stepwise manner. The computed tomography system of claim 2 .

4. When the object to be detected is recognized from the captured X-ray transmission image, the process for generating the computed tomography image is stopped. The computed tomography system of claim 1 .

5. Attempting to recognize the image of the detection object from the X-ray transmission images in sequence so that the angular difference between the relative positions around the vertical axis when the adjacent X-ray transmission images were taken in the order of performing image recognition becomes smaller in stages.

5. The computed tomography system of claim 4.

6. The X-ray imaging device captures X-ray transmission images by scanning using a line sensor, and the X-ray transmission images are sequentially captured by the X-ray imaging device so that the angular difference of the relative position around the vertical axis when capturing the X-ray transmission images in the order of capture becomes smaller in stages.

6. A computed tomography system according to claim 3 or 5.

7. The angular difference around the vertical axis between the photographing directions of two adjacent X-ray transmission images taken to generate a computed tomography image can be changed.

7. A computed tomography system according to any one of claims 1 to 6.

Images