Intelligent baggage screening system and method

Abstract

The present application relates to a luggage item intelligent security inspection system and method. The system comprises: a first detection device for performing first detection on a detected item on a conveying device; a second detection device for performing second detection on one or more specific regions of the detected item determined as suspicious after the first detection; wherein the conveying device comprises a buffer conveying section located between the first detection device and the second detection device, for conveying the suspicious detected item to the second detection device; and a control device for controlling operation of the buffer conveying section according to the conveying condition of the suspicious detected item on the buffer conveying section to buffer the difference between the detection rates of the first detection device and the second detection device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of security inspection, and in particular to a dual-stage security inspection system and method. BACKGROUND

[0002] Digital Radiography (DR) and Computed Tomography (CT) have become important technical means in the field of public security due to the advantages of convenient and fast detection and wide range of detected objects, covering many application scenarios such as airports, subways, and customs. However, CT and DR detection are difficult to effectively distinguish substances with similar atomic numbers and electron densities, so there is a high false positive rate in actual applications.

[0003] X-ray diffraction (XRD) technology can provide structure information at the molecular level of the substance by measuring the diffraction spectrum of the substance, and has strong specificity. However, if XRD detection is to be used for comprehensive detection of the interior of an object, the scanning time will be too long. If the XRD detection speed is increased by increasing the area of the detector or increasing the optical, mechanical and electrical currents, etc., the cost will increase, the protection difficulty will increase, and other problems will occur, affecting the practicality of the product.

[0004] In recent years, a scheme has been proposed to combine CT or DR detection with XRD detection to improve detection accuracy. However, traditionally, CT or DR detection and XRD detection are simply combined, and since the time required for XRD detection is longer than that for CT or DR detection, it is inevitable that the detection time will be greatly prolonged, affecting the security inspection efficiency and detection efficiency. SUMMARY

[0005] According to an aspect of the present application, a dual-stage security inspection system is provided, including: a first detection device for performing first detection on a detected object on a conveying device; a second detection device for performing second detection on one or more specific regions of the detected object determined to be suspicious after the first detection, wherein the conveying device includes a buffer conveying section located between the first detection device and the second detection device, for conveying the suspicious detected object to the second detection device; and a control device for controlling the operation of the buffer conveying section according to the conveying condition of the suspicious detected object on the buffer conveying section to buffer the difference between the detection rates of the first detection device and the second detection device.

[0006] According to another aspect of the present application, there is provided a dual-stage security inspection method, comprising: performing a first-stage inspection on inspected items on a conveying device by a first-stage inspection device; performing a second-stage inspection on one or more specific regions of the inspected items determined as suspicious after the first-stage inspection by a second-stage inspection device, wherein the conveying device comprises a buffer conveying section located between the first-stage inspection device and the second-stage inspection device for transporting the suspicious inspected items to the second-stage inspection device; and controlling, by a control device, operation of the buffer conveying section to buffer a difference between inspection rates of the first-stage inspection device and the second-stage inspection device according to a transportation condition of the suspicious inspected items on the buffer conveying section.

[0007] According to another aspect of the present application, there is provided an XRD inspection device, comprising: a radiation source having a row of multiple radiation source focal points, each of which can be independently controlled to emit radiation; a front collimator arranged such that the radiation from the radiation source is irradiated onto an inspected item in one or more fan beam planes; and a detector module comprising one or more groups of detectors, each of which corresponds to one of the one or more fan beam planes and is configured to detect radiation that has been diffracted by the inspected item and collimated in the fan beam plane corresponding to the group of detectors, wherein each group of detectors comprises one or more detectors, each of which is configured to detect radiation that has been diffracted by a specific location in the inspected item and collimated, the specific location being at an intersection position of a pixel element of the detector and the fan beam plane corresponding to the group of detectors in a direction opposite to a corresponding collimation direction.

[0008] According to another aspect of the present application, there is provided an XRD inspection method, comprising: emitting radiation by a radiation source, wherein the radiation source has a row of multiple radiation source focal points, each of which can be independently controlled to emit radiation; irradiating the radiation from the radiation source onto an inspected item in one or more fan beam planes by a front collimator; and detecting, by a detector module, radiation that has been diffracted by the inspected item and collimated in the one or more fan beam planes, wherein the detector module comprises one or more groups of detectors, each of which corresponds to one of the one or more fan beam planes and is configured to detect radiation that has been diffracted by the inspected item and collimated in the fan beam plane corresponding to the group of detectors, wherein each group of detectors comprises one or more detectors, each of which is configured to detect radiation that has been diffracted by a specific location in the inspected item and collimated, the specific location being at an intersection position of a pixel element of the detector and the fan beam plane corresponding to the group of detectors in a direction opposite to a corresponding collimation direction.

[0009] According to another aspect of the present invention, a two-stage security inspection method is provided, comprising: performing a primary inspection on an inspected item on a primary inspection conveyor section of a conveyor using a primary inspection device; allowing inspected items deemed unsustainable after the primary inspection to pass through a release conveyor section of the conveyor; allowing inspected items deemed suspicious after the primary inspection to be conveyed to a buffer conveyor section of the conveyor, wherein the buffer conveyor section is used to transport suspicious inspected items to a secondary inspection device; controlling the operation of the buffer conveyor section by a control device based on the transport status of suspicious inspected items on the buffer conveyor section to buffer the difference between the detection rates of the primary and secondary inspection devices; performing a secondary inspection on each suspicious area of ​​the suspicious inspected item using the secondary inspection device; allowing inspected items deemed unsustainable after the secondary inspection to pass through a release conveyor section of the conveyor; and allowing inspected items deemed suspicious after the secondary inspection to be conveyed to an inspection conveyor section of the conveyor for further inspection.

[0010] According to the dual-level security inspection system and dual-level detection method of this application, the buffer transmission section and associated control equipment effectively buffer the difference in detection rates between the first-level and second-level detection. This avoids the need to pause other parts of the security inspection system due to the accumulation of detection tasks at the second-level detection equipment caused by the difference in detection rates between the two levels, thereby improving throughput and detection efficiency. Furthermore, the use of a multi-focus, multi-sector beam planar output method in the second-level detection can cover as much of the range as possible in the transmission direction. Attached Figure Description

[0011] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0012] Figure 1 The figure shows a schematic diagram of a two-level security inspection system according to an embodiment of this application;

[0013] Figure 2 The figure shows a schematic diagram of a buffered transmission segment according to an embodiment of the present application;

[0014] Figure 3 The figure illustrates an embodiment according to this application. Figure 1 A schematic diagram of an imaging device installed in a two-level security inspection system;

[0015] Figure 4 The figure shows a schematic diagram of an XRD inspection device according to an embodiment of this application;

[0016] Figure 5 The figure shows a schematic diagram of an XRD inspection device according to an embodiment of this application;

[0017] Figure 6 is a flow chart illustrating a dual-stage security inspection method according to an embodiment of the present application;

[0018] Figure 7 is a flow chart illustrating an XRD detection method according to an embodiment of the present application;

[0019] Figure 8 is an application scenario diagram illustrating a dual-stage security inspection system and method according to an embodiment of the present application; and

[0020] Figure 9 is a flow chart illustrating a dual-stage security inspection method according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] The present application proposes a composite dual-stage security inspection system and method, in which the two-stage detection is not simply combined but linked through a unique buffer conveying section design, which can avoid the requirement for suspending other parts of the security inspection system due to the accumulation of detection tasks at the secondary detection equipment caused by the different detection rates of the two-stage detection, thereby improving the throughput efficiency and detection efficiency. In addition, the present application also proposes a unique security inspection equipment, in which the ray emitting module and the detector module have a unique structure and arrangement, which can help to achieve efficient detection.

[0022] The dual-stage security inspection system and method according to an embodiment of the present application will be described below in conjunction with Figures 1-9 .

[0023] Figure 1 illustrates a schematic diagram of a dual-stage security inspection system 100 according to an embodiment of the present application. As Figure 1 shown, the dual-stage security inspection system 100 includes a primary detection equipment 102 for performing primary detection on a subject article 106 on a conveying equipment 104, a secondary detection equipment 108 for performing secondary detection on one or more specific regions of the subject article 106 determined to be suspicious after the primary detection, wherein the conveying equipment 104 includes a buffer conveying section 1041 located between the primary detection equipment 102 and the secondary detection equipment 108 for conveying the suspicious subject article 106 to the secondary detection equipment 108, and a control equipment 110 for controlling the operation of the buffer conveying section 1041 to buffer the difference between the detection rates of the primary detection equipment 102 and the secondary detection equipment 108 according to the conveying condition of the suspicious subject article on the buffer conveying section 1041.

[0024] With this two-stage detection, the primary detection device 102 acquires information of the inspected item, such as but not limited to the geometry, atomic number, electron density, X-ray attenuation coefficient of the whole and all the objects inside the inspected item, information of the internal interference objects, and location information of the internal suspicious objects. The secondary detection device 108 performs targeted local inspection (i.e. inspection of one or more specific regions (each suspicious region) of the suspicious inspected item) on the inspected item that has been determined as suspicious after the primary detection. These information is transmitted to the processing device for suspicious object judgment, risk level assessment, etc. so as to make subsequent decision of release or opening-box inspection, greatly reducing the false positive rate and reducing subsequent unnecessary manual cost.

[0025] The conveying device 104 is configured to drive the inspected item to be subjected to the detection of the security inspection system 100. In some implementations, the primary detection device 102 and the secondary detection device 108 can have different detection rates, such as the detection rate of the primary detection device 102 is higher than that of the secondary detection device 108. In this case, it is possible that the detection task at the secondary detection device 108 is accumulated and requires, for example, the primary detection device 102 to pause for waiting until the secondary detection device 108 finishes the existing detection task, thereby affecting the throughput efficiency and detection efficiency of the whole security inspection system. The arrangement of the buffer conveying section 1041 and the associated control device 110 can effectively coordinate the detection of the two-stage detection devices to avoid the requirement of pausing other parts of the security inspection system before the secondary detection device finishes its existing task, thereby improving the throughput efficiency and detection efficiency of the whole security inspection system.

[0026] The buffer conveying section can be constructed in many ways. In some embodiments, the buffer conveying section can be constructed by a cylindrical member. Figure 2 A schematic diagram of a buffer conveying section according to an embodiment of the present application is shown. As shown in FIG. 1, the buffer conveying section 1041 is a cylindrical member having a hollow interior 1042. The buffer conveying section 1041 is configured to receive the inspected item from the primary detection device 102 and to convey the inspected item to the secondary detection device 108. The buffer conveying section 1041 is configured to have a length sufficient to accommodate the inspected item to be subjected to the detection of the secondary detection device 108. The buffer conveying section 1041 is configured to have a diameter sufficient to accommodate the inspected item to be subjected to the detection of the secondary detection device 108. Figure 2The buffer conveyor section 1041 may include multiple independently rolling cylindrical members 112, arranged sequentially along the conveying direction. As these cylindrical members 112 roll, the inspected item 106 can be conveyed toward the secondary inspection device 108. The control device 110 selectively controls one or more of the cylindrical members 112 to roll or stop rolling based on the conveying status of the inspected item on the buffer conveyor section 1041, thereby controlling the conveying of each inspected item on the buffer conveyor section 1041. The material of the cylindrical members is not limited, as long as it is suitable for conveying the inspected item. The diameter of the cylindrical members can be set according to the distance between the primary and secondary inspection devices. The control device 110 can be implemented such that each cylindrical member can be controlled by its own associated control unit, or by a centralized control device. It should be understood that this application is not limited to this buffering method, but in some implementations, other methods can be used to achieve this buffering of the difference in inspection rates between the primary inspection device 102 and the secondary inspection device 108.

[0027] The transport status of inspected items on the buffer transport section can be determined in many ways. In some embodiments, the transport status of inspected items on the buffer transport section can be determined by image information captured by an imaging device. Figure 3 The figure illustrates an embodiment according to this application. Figure 1 A schematic diagram showing the installation of imaging equipment in a two-level security screening system. (See diagram for example.) Figure 3 As shown, in Figure 1 The two-stage security inspection system 100 may include an imaging device 114 for imaging a buffer transport section 1041. A control device 110 determines the transport status of inspected items on the buffer transport section based on the image information captured by the imaging device 114. Specifically, this image information can identify which inspected items should remain stationary and which should continue moving forward. For example, when the distance between inspected items is less than a predetermined threshold, it is determined that the following inspected items should pause, while when the distance between inspected items is greater than or equal to the predetermined threshold, it is determined that the relevant inspected items should continue forward; similarly, when the number of inspected items within a transport distance exceeds a predetermined threshold, it is determined that the following inspected items should pause, while when the number of inspected items within a transport distance is less than or equal to the predetermined threshold, it is determined that the relevant inspected items should continue forward. It should be understood that the embodiments of this application are not limited thereto. Based on the inspected items that need to be controlled to remain stationary or continue moving forward, the corresponding cylindrical parts are identified, and instructions are given to these cylindrical parts to roll or stop rolling.

[0028] Imaging device 114 can be a standalone device or can be integrated with other devices. For example... Figure 3As shown, two imaging devices 114 are shown, one of which is attached at the exit end of the primary inspection device 102 and the other is suspended above the entrance end of the secondary inspection device 108. However, it should be understood that the number and arrangement of the imaging devices are not limited to the specific arrangements described herein, as long as the arrangement enables suitable imaging of the buffer conveyor section. For example, the imaging devices can be arranged at only one of the inspection devices, or one or more imaging devices can be arranged above the buffer conveyor section, or any combination thereof. The image information obtained by the imaging devices is transmitted to the processing device of the dual-stage security inspection system 100 for processing to obtain the transport condition of the inspected items on the buffer conveyor section, such as but not limited to the number of the inspected items on the buffer conveyor section and the distance / position between each other, etc. The control device controls the operation of the buffer conveyor section based on this information.

[0029] In addition, during the transport of the inspected items from the primary inspection device 102 to the secondary inspection device 108, there is inevitable friction and movement, etc. The position of the suspicious region locked by the detection of the primary inspection device 102 can have changed when used for further detection at the secondary inspection device, which is not conducive to the targeted and accurate detection of the secondary inspection device. The image information of the imaging device 114 can also include information about the posture of the inspected items before the inspected items enter the scanning of the secondary inspection device 108. With this information, the position of the suspicious region can be registered, so that the secondary inspection device 108 can accurately target the suspicious region locked by the primary inspection device 102 based on the position information of the suspicious region provided by the primary inspection device 102 and the imaging information provided by the imaging device to implement targeted detection.

[0030] In some implementations, the imaging device 114 can include any one of the following: a visible light camera, an infrared imaging device, an X-ray digital radiography device. It should be understood that the imaging device is not limited to these specifically described imaging devices, but can employ any imaging device that is already known or will be known in the art.

[0031] In some embodiments, the transport status of the inspected articles on the buffer conveyor section can be determined by optical information captured by an optical sensor device. The optical sensor device can be incorporated in the system similarly to the imaging device. The optical sensor device can include at least one of an infrared sensor and a laser sensor. When an inspected article on the buffer conveyor section moves to a certain position, the light path is blocked, and thus the inspected article and its position can be determined accordingly. Then, according to the comparison of the distance between the inspected articles or the number of the inspected articles with a threshold value (i.e., the occupation and queuing of the inspected articles on the conveyor section are determined), it can be determined which inspected articles should remain stationary and which inspected articles should continue to move forward, and further, the corresponding cylindrical members are instructed to roll or stop rolling.

[0032] In some embodiments, the transport status of the inspected articles on the buffer conveyor section can be determined by gravity information obtained by a gravity sensor device (not shown in the figures). Specifically, each cylindrical member is equipped with a corresponding gravity sensor, and each gravity sensor can sense the gravity condition on the corresponding cylindrical member. Through the gravity information sensed by each gravity sensor, the inspected articles and their positions can be determined. Then, according to the comparison of the distance between the inspected articles or the number of the inspected articles with a threshold value (i.e., the occupation and queuing of the inspected articles on the conveyor section are determined), it can be determined which inspected articles should remain stationary and which inspected articles should continue to move forward, and further, the corresponding cylindrical members are instructed to roll or stop rolling.

[0033] Although the above describes three ways that can be used to determine the transport status of the inspected articles on the buffer conveyor section, it should be understood that these ways can not only be used individually, but also in any combination.

[0034] In some embodiments, the primary inspection device 102 can be any of a computed tomography (CT) inspection device and a radiographic (DR) inspection device. For CT inspection, CT information of the inspected articles can be obtained, such as but not limited to the geometry, atomic number, electron density, X-ray attenuation coefficient of the whole and internal objects of the inspected articles, information of internal interference objects, and position information of internal suspicious objects. In some embodiments, the secondary inspection device 108 can be an X-ray diffraction (XRD) inspection device. In some embodiments, the secondary inspection device 108 can use a conventional XRD inspection device. In some embodiments, the secondary inspection device 108 can use a specific XRD inspection device according to the present disclosure, which will be described in detail below in connection with the detailed description. Figure 4 and Figure 5 detailed description.

[0035] Figure 4 and Figure 5FIG. 1 illustrates a schematic diagram of an XRD inspection apparatus 400 as an example of the secondary inspection apparatus 108 according to an embodiment of the present application. In Figure 4 and Figure 5 In the Cartesian coordinate system of the three-dimensional right-handed helix is established, the direction perpendicular to the conveying apparatus 104 (e.g. a conveyor belt) is defined as the y direction, the direction of the movement of the conveying apparatus 104 is defined as the z direction, and the x direction is determined according to the right-handed helix rule.

[0036] As shown in Figure 4 and Figure 5 The XRD inspection apparatus 400 includes a radiation emitting module 402 for emitting radiation at the inspected item 106 in one or more fan planes. The radiation emitting module 402 can include a radiation source 4021 for emitting radiation. In some embodiments, the radiation source 4021 has a plurality of radiation source foci, each of which can be independently controlled to emit radiation. As shown in Figure 4 and Figure 5 The radiation source 4021 has a plurality of radiation source foci 4023 (4023-1 and 4023-2 are specifically marked in Figure 5 The radiation source foci 4023 are arranged in a row, e.g. along the x direction. Such arrangement of multiple radiation source foci allows more scanning range to be covered in the x direction. The number of radiation source foci is not limited and can be selected according to the actual requirements of the XRD inspection apparatus. Each of the radiation source foci 4023 can be independently controlled to emit radiation.

[0037] The radiation emitting module 402 further includes a front collimator 4022. The front collimator 4022 is arranged between the radiation source 4021 and the inspected item 106 for causing the radiation from the radiation source 4021 to be irradiated at the inspected item 106 in one or more fan planes. As shown in Figure 4 The front collimator 4022 causes the radiation from the radiation source 4021 to be irradiated in two fan planes S1-S2. It should be understood that the number of fan planes is not limited to two as described herein, but can be more or fewer fan planes. With such multi-fan plane irradiation, more scanning range can be covered in the z direction.

[0038] In some embodiments, one or more of the plurality of radiation source foci are selected to emit radiation. In some implementations, the selected radiation source foci can be selected according to one or more specific regions on the inspected item determined based on the information from the primary inspection, such that at least one of the one or more specific regions can be covered by at least one fan plane. In some embodiments, the one or more specific regions can be determined according to the location of the suspect object, the location of the interfering object around the suspect object in the inspected item determined based on the information from the primary inspection. As shown in Figure 5As shown, there can be two suspicious objects W1, W2 (indicated by circles) on the inspected object 106, and there are interference objects (e.g., metals) G1, G2 (indicated by rectangles) around the periphery of the suspicious objects W1, W2. According to the positions of the interference objects G1, G2 and the suspicious objects W1, W2, a region including the positions of the suspicious objects but not including the positions of the interference objects can be determined, so that the suspicious objects can be detected more specifically. In Figure 5 Correspondingly, two focal points 4023-1, 4023-2 of the two ray sources are selectively controlled to emit rays. The rays form two fan-beam planes S1 and S2 via the front collimator 4022, which cover the specific regions including the positions of the suspicious objects at the two places, respectively. As mentioned before, the front collimation mode with multiple fan-beam planes can cover as many scanning ranges in the z direction as possible at the same time. It should be understood that in some embodiments, there can be a case where the fan-beam planes are not enough to cover all the specific regions, in which case, after the detection of those specific regions covered by the fan-beam planes is completed, the position of the inspected object can be controlled to move appropriately by a transfer section within the XRD detection device 400, so that those specific regions not covered by the fan-beam planes can be covered, thereby enabling further detection.

[0039] The XRD detection device 400 further comprises a detector module for detecting the rays diffracted by the inspected object and collimated, wherein the detector module comprises one or more groups of detectors, each group of detectors corresponding to one or more fan-beam planes and being configured to detect the rays diffracted by the inspected object and collimated in the fan-beam plane corresponding to the group of detectors.

[0040] As Figure 4 and Figure 5 As shown, since two fan-beam planes S1-S2 are shown, two groups of detectors 404-1 to 404-2 are shown accordingly. Specifically, a first group of detectors 404-1 is provided corresponding to the fan-beam plane S1, and a second group of detectors 404-2 is provided corresponding to the fan-beam plane S2. It should be understood that for more or fewer fan-beam planes, more or fewer groups of detectors can be provided accordingly.

[0041] Each group of detectors comprises one or more detectors, each detector being configured to detect the rays diffracted by a specific position in the inspected object and collimated, the specific position being at the intersection position of the fan-beam plane corresponding to the group of detectors in a direction opposite to the corresponding collimation direction with respect to the pixel elements of the detector. It should be understood that in Figure 4In the drawings, only one detector is shown for each group of detectors, however, in practice, one or more detectors in each group of detectors can be arranged in the x direction, which can be arranged in a straight line or in an arc, without much restriction, as long as the detected is the diffracted and collimated ray emitted by the fan beam plane they are responsible for. In Figure 5 In the drawings, only one detector is shown for each group of detectors as an example due to the mobility of the detectors, which will be described in detail below. However, it should also be understood that there can be more than one mobile detector for each group of detectors.

[0042] For example, as shown in Figure 4 and Figure 5 Corresponding to the fan beam plane S1, one of the detectors (the detector shown in the figure) in the corresponding group of detectors 404-1 is used to detect the diffracted and collimated ray of the ray in the fan beam plane S1 after the suspicious object 106 position W1 diffracts, which is at the intersection position of the pixel element of the detector with the fan beam plane S1 in the direction opposite to the corresponding collimation direction. That is, for the fan beam plane S1, one of the detectors in the corresponding group of detectors 404-1 detects the ray that can come from the diffracted and collimated ray of multiple ray source foci 4023 (such as 4023-1 and 4023-2) in the fan beam plane S1, where the diffracted position is the intersection position of the pixel element in the detector with the fan beam plane S1 in the direction opposite to the corresponding collimation direction (since a straight line intersects a plane, there is only one intersection point). In other words, the diffraction angle needs to be calculated according to the positions of the two ray source foci 4023-1 and 4023-2. As Figure 5 In the drawings, the diffraction angles of the two ray source foci diffracted at the suspicious object W1 are not the same, but the paths of the outgoing light rays are the same, entering the same detector, so the signal of the detector is the superposition of the diffracted signals of different diffraction angles of different ray source foci at the same position. The case is similar for the fan beam plane S2, which will not be described here.

[0043] It should be understood that each detector can contain multiple pixel elements to enable a detection range of a certain depth range in the y direction. In addition, it should be noted that the fan beam plane and the detector group are one-to-one, that is, each group of detectors is not allowed to detect the diffracted rays of the rays emitted by the fan beam planes other than the fan beam planes they are responsible for or correspond to. For example, the intersection of each pixel element of the detector in the group of detectors corresponding to the fan beam plane S1 with the fan beam plane S2 in the direction opposite to the corresponding collimation direction must be located outside the detection area (i.e. outside the volume of the inspected object), otherwise it will detect the diffracted signals of more than one position in the detection area, which will cause confusion. This is a restriction that must be considered when designing the geometric layout of the multi-fan beam XRD detection device.

[0044] In some embodiments, the detectors can be photon counting detectors. It should be understood that in other embodiments, the detectors can also employ other types of detectors.

[0045] With continued reference to Figure 4 and Figure 5 Corresponding to each detector, a post-collimator is provided. As for the detectors shown in the figure, post-collimators 405-1 and 405-2 are correspondingly provided. The post-collimators are arranged between the inspected article 106 and each detector, such that the rays diffracted from the inspected article 106 are selectively shot into the corresponding detector.

[0046] In some embodiments, each group of detectors can employ a multi-detector stationary mode. In this mode, one or more detectors in each group of detectors are stationary detectors, i.e., their respective positions are fixed, and these one or more detectors can simultaneously detect the rays diffracted and collimated within the one or more specific regions locked by the primary detection device 102 in relation to the fan beam plane corresponding to the group of detectors. Figure 4 In the multi-detector stationary mode, one or more detectors in the first group of detectors 404-1 corresponding to the fan beam plane S1 simultaneously detect the rays diffracted and collimated within the one or more specific regions locked by the primary detection device 102 in relation to the fan beam plane S1. Similarly, one or more detectors in the second group of detectors 404-2 corresponding to the fan beam plane S2 simultaneously detect the rays diffracted and collimated within the one or more specific regions locked by the primary detection device 102 in relation to the fan beam plane S2. In this mode, since these one or more detectors can simultaneously detect, it has the advantage of high detection speed.

[0047] In some embodiments, at least one group of detectors can employ a few-detector movable mode. In this mode, compared to the multi-detector stationary mode, at least one of the one or more detectors included in the at least one group of detectors is a movable detector. In this mode, the arrangement of the one or more detectors included in each group of detectors is substantially the same as in the multi-detector stationary mode. Only in this mode, since at least one of the detectors in the at least one group of detectors is movable, the number of detectors used is less than in the multi-detector stationary mode. In this mode, each movable detector can be independently controlled to move, so that one of the at least one movable detector in the at least one group of detectors can be moved to a position corresponding to one of the at least one specific region, thereby enabling targeted accurate detection. In some embodiments, the movement trajectory of one of the at least one movable detector to one of the at least one specific region is any one of a straight line and an arc.

[0048] Referring to Figure 5 For example, when a certain area in the x direction (e.g., the area containing the suspicious object Wl) needs to be detected, one of the movable detectors in the group of detectors 404-1 corresponding to the fan beam plane S1 covering the area (e.g., the detector shown in the figure) can be moved to a position corresponding to the certain area (avoiding the interfering object) to achieve the detection of the certain area.

[0049] It should be understood that the XRD detection apparatus 400 can select the optimal combination of the focal point of the radiation source and the detector. When more than one pair of the focal point of the radiation source and the detector satisfying the requirement of avoiding the interfering object, more than one pair of the focal point of the radiation source and the detector can be selected to perform data acquisition. This can shorten the beam-out time and improve the detection efficiency. Moreover, since the obtained diffraction data is from more than one crystal plane direction, the diffraction peaks are more complete and the detection result is more accurate.

[0050] It should be understood that the few-detector movable mode is slower than the multi-detector stationary mode, but as mentioned above, it can save the detector modules and thus reduce the cost of the system. Moreover, in the few-detector movable mode, the detectors are positioned relatively accurately, which can effectively reduce the interference and thus improve the detection accuracy.

[0051] Regardless of the mode, the XRD detection apparatus 400 can perform accurate detection based on the detection information of the primary detection apparatus, such as the information of the position of the suspicious object in the inspected article (optionally, the imaging and registration information of the imaging apparatus can also be used). Since the XRD detection apparatus 400 adopts the multi-focal point and multi-fan beam plane beam-out mode and the corresponding detector arrangement as described above, it is helpful to perform omnidirectional detection of the inspected article, thereby reducing the false negative cases and improving the detection accuracy.

[0052] It should be noted that although the XRD detection apparatus discussed above is suitable for use as the secondary detection apparatus in the secondary security system discussed in the embodiments of the present application, the XRD detection apparatus can be used alone to detect the inspected article. In this case, the suspicious areas on the inspected article can be pre-marked and the information is transmitted to the XRD detection apparatus to perform the detection.

[0053] Figure 6 is a flowchart showing a dual-level security method according to an embodiment of the present application. The method can be implemented by the dual-level security system as discussed above.

[0054] As Figure 6As shown, the two-stage security inspection method 600 according to the embodiments of the present application comprises: S601, performing first-stage detection on the inspected items on the conveying device by the first-stage detection device; S602, performing second-stage detection on one or more specific regions of the inspected items determined as suspicious after the first-stage detection by the second-stage detection device, wherein the conveying device comprises a buffer conveying section located between the first-stage detection device and the second-stage detection device for transporting the suspicious inspected items to the second-stage detection device; and S603, controlling the operation of the buffer conveying section by the control device according to the transportation of the suspicious inspected items on the buffer conveying section to buffer the difference between the detection rates of the first-stage detection device and the second-stage detection device.

[0055] In some embodiments, the buffer conveying section comprises a plurality of cylindrical members independently rollable, which are arranged in sequence along the conveying direction. The two-stage security inspection method according to the embodiments of the present application can further comprise selectively controlling one or more of the plurality of cylindrical members to roll or stop rolling by the control device according to the transportation of the suspicious inspected items on the buffer conveying section. As described before for the system embodiments, the material of the cylindrical members is not limited as long as it is suitable for conveying the inspected items. The diameter of the cylindrical members can be set according to the distance between the first-stage detection device and the second-stage detection device. The control device can be implemented such that each cylindrical member can be controlled by a respective associated control unit or by a centralized control device.

[0056] In some embodiments, the dual-stage screening method according to embodiments of the present application can further include determining the transport condition of the suspicious inspected item on the buffer transport section from information obtained from at least one of the imaging device, the optical sensor device, and the gravity sensor device. For example, in the use case of using the imaging device, the transport condition of the inspected item on the buffer transport section can then be determined from the image information captured by the imaging device by imaging toward the buffer transport section. The imaging device can be a separate device or can be integrated with other devices. The imaging device can be attached or integrated to any of the detection devices, or be installed at any suitable location suitable for imaging toward the buffer transport section. In the use case of using the optical sensor device, the transport condition of the inspected item on the buffer transport section can then be determined from the optical information sensed by the optical sensor by sensing the condition of light from the inspected item on the buffer transport section. The optical sensor device can be at least one of an infrared sensor and a laser sensor. Similar to the imaging device, the optical sensor device can be a separate device or can be integrated with other devices. The optical sensor device can be attached or integrated to any of the detection devices, or be installed at any suitable location suitable for receiving the optical information from the inspected item on the buffer transport section. In the use case of using the gravity sensor device, the transport condition of the inspected item on the buffer transport section can then be determined from the gravity information sensed by each gravity sensor by sensing whether there is an inspected item on the corresponding cylindrical piece coupled with each gravity sensor. The transport condition on the buffer transport section such as, but not limited to, the number of inspected items on the buffer transport section and the distance / position between each other, etc. More detailed description about the imaging device, the optical sensor device, and the gravity sensor device can be referred to the details described above for the system embodiments, and thus will not be repeated here.

[0057] In some embodiments, the secondary detection can be X-ray diffraction (XRD) detection. Figure 7 is a flowchart illustrating an XRD detection method according to embodiments of the present application. The XRD detection method 700 according to embodiments of the present application includes: S701, emitting, by a ray emitting module, rays toward an inspected item in one or more fan beam planes; and S702, detecting, by a detector module, rays that are diffracted by the inspected item and collimated after the one or more fan beam planes, wherein the detector module includes one or more groups of detectors, each group of detectors corresponding to one of the one or more fan beam planes and being configured to detect rays that are diffracted by the inspected item and collimated after the fan beam plane corresponding to the group of detectors.

[0058] In some embodiments, each set of detectors includes one or more detectors, each detector being configured to detect the rays that have been diffracted at a specific location in the inspected item and collimated in a direction opposite to the corresponding collimation direction at an intersection of a pixel element of the detector with a fan plane corresponding to the set of detectors.

[0059] In some embodiments, step S701 can include emitting the rays by a ray source in the ray emitting module, wherein the ray source has a row of a plurality of ray source foci, each ray source focus being independently controllable to emit the rays; and collimating the rays from the ray source by a front collimator in the ray emitting module to illuminate the suspicious inspected item in one or more fan planes.

[0060] In some embodiments, the one or more ray source foci of the plurality of ray source foci are selected to emit the rays according to one or more specific regions on the inspected item determined based on the information of the primary detection, such that at least one of the one or more specific regions is covered by at least one of the one or more fan planes. In some embodiments, the one or more specific regions are determined according to a location of the suspicious object in the inspected item, a location of the interfering object around the suspicious object based on the information of the primary detection.

[0061] In some embodiments, the one or more detectors in each set of detectors can include at least one movable detector that is independently controllable to move. The XRD detection method according to embodiments of the present application further includes S703, moving one of the at least one movable detector in a set of detectors corresponding to each of the at least one fan plane to a position corresponding to one of the one or more specific regions. The moving trajectory of the one of the at least one movable detector to the one of the at least one specific region is any one of a straight line shape and an arc shape.

[0062] It should be noted that although all steps S701-S703 are illustrated in Figure 7 , as described above, the detectors can adopt the multi-detector stationary mode and the few-detector movable mode, and the step of moving the detectors of step S703 is only included when the few-detector movable mode is used, and thus is illustrated in the figure with a dashed box. It should also be understood that although the above Figure 7 is described as the secondary detection in the two-stage security inspection method in Figure 6 , the detection method in Figure 7 can be used alone. In this case, the suspicious regions on the inspected item can be pre-marked and this information is transmitted to the XRD detection device to perform the detection.

[0063] According to the two-stage security inspection method of the embodiments of the present application, the detection of the two-stage detection devices can be effectively coordinated by buffering the difference between the detection rates of the first-stage detection device and the second-stage detection device, preventing the requirement for suspending other parts of the security inspection system due to the accumulation of detection tasks at the second-stage detection device, thereby improving the through efficiency and detection efficiency of the entire security inspection system. In addition, the multi-fan-beam planar beam-out collimation method is used in the second-stage detection, which can cover as many ranges as possible in the z direction at the same time. In addition, the use of mobile detectors can reduce system cost and effectively reduce interference and thus improve detection accuracy.

[0064] Figure 8 is a diagram illustrating an application scenario of a two-stage security inspection system and method according to an embodiment of the present application. In Figure 8 , there are two-stage detection devices, i.e., a first-stage detection device 801 and a second-stage detection device 802. The first-stage detection device 801 is used for first-stage detection, such as CT detection, on the inspected articles 803 on the conveying device. The second-stage detection device 802 is used for second-stage detection, such as XRD detection, on the inspected articles 803 that have been determined to be suspicious after the first-stage detection.

[0065] The conveying device is used to convey the inspected articles under the drive to undergo the entire detection of the security inspection system. As Figure 8 indicated, the conveying device includes a buffer conveying section 8041 located between the first-stage detection device 801 and the second-stage detection device 802, which is used to convey the suspicious inspected articles 803 to the second-stage detection device 802. In association with the buffer conveying section 8041, there is a control device (not shown in the figure) for controlling the operation of the buffer conveying section 8041 to buffer the difference between the detection rates of the first-stage detection device 801 and the second-stage detection device 802 according to the conveying situation of the suspicious inspected articles 803 on the buffer conveying section 8041.

[0066] In addition to the buffer conveying section 8041, the conveying device also includes a first-stage detection conveying section 8042 and a second-stage detection conveying section 8043, as Figure 8 indicated. The first-stage detection conveying section 8041 is used for the conveying of the inspected articles in the first-stage detection part. For example, the inspected articles are fed into the first-stage detection device 801 and conveyed through the first-stage detection device 801. The second-stage detection conveying section 8043 is used for the conveying of the inspected articles in the second-stage detection part. For example, the inspected articles are conveyed through the second-stage detection device 802 and fed out from the second-stage detection device 802.

[0067] Further, the conveying device comprises a first release conveying section which is connected to the conveying section at the exit of the primary inspection device 801. As mentioned above, the inspected items which have been subjected to the inspection of the primary inspection device 801 and are considered suspicious can be transported to the secondary inspection device 802, while the inspected items which have been subjected to the inspection of the primary inspection device 801 and are considered non-suspicious can be conveyed from the conveying section at the exit of the primary inspection device 801 to the first release conveying section instead of being transported to the secondary inspection device 802. This improves the efficiency of the security check for those items which can be determined as safe by the primary inspection device 801 only. The conveying device can further comprise a second release conveying section which is connected to the conveying section at the exit of the secondary inspection device 802. The inspected items which have been subjected to the inspection of the secondary inspection device 802 and are considered non-suspicious can be conveyed from the conveying section at the exit of the secondary inspection device 802 to the second release conveying section for releasing the inspected items. In Figure 8 the first release conveying section and the second release conveying section are merged together and referred to as a release conveying section 8044.

[0068] The conveying device can further comprise an inspection conveying section 8045 which is connected to the conveying section at the exit of the secondary inspection device 802. The inspected items which have been subjected to the inspection of the secondary inspection device 802 and are considered suspicious can be conveyed from the conveying section at the exit of the secondary inspection device 802 to the inspection conveying section 8045 for opening and inspection by security personnel.

[0069] Further, as shown in Figure 8 , an imaging device 805 is provided. The imaging device 805 is attached above the entrance end of the secondary inspection device 802 for imaging towards the buffer conveying section 8041. The image information obtained from the imaging device 8041 can be used to derive transport situation information for controlling the buffer conveying section 8041. In addition, the imaging of the buffer conveying section by the imaging device 805 can also include information about the posture of the inspected items. With this information, the position registration of the suspicious area can be achieved so that the secondary inspection device 802 can accurately perform further inspection targeted at the suspicious area locked by the primary inspection device 801 based on the position information of the suspicious area provided from the primary inspection device 801 and the imaging information provided from the imaging device.

[0070] Further, as shown in Figure 8As shown, a processing device 806 is provided. The processing device 806 is used to acquire information of each component and transmit relevant information to the corresponding component. The processing device 806 can be a collection of distributed processing devices or in the form of a central processing device. In the case of distributed processing devices, each component can include a respective processing device. For example, the primary inspection device 801 can include, in addition to the detector device, a processing device for evaluating the risk of each suspicious object of the inspected article and determining the location thereof based on the CT information (such as but not limited to: the geometric shape of all objects inside the inspected article, atomic number, electron density, X-ray attenuation coefficient, information of internal interference objects, and location information of internal suspicious objects) detected by the detector device; the secondary inspection device 802 can include, in addition to the detector device, a processing device for evaluating the risk of each suspicious object of the inspected article based on the CT information of the primary inspection device 801 and the information detected by the detector device thereof. The evaluation algorithm includes but is not limited to: establishing a mapping relationship from the CT information and the XRD information to whether the inspected article is contraband through a lookup table, a polynomial function, a neural network, etc., thereby realizing the two-stage discrimination of the risk of the inspected article. Similarly, the imaging device 805 can include, in addition to the camera for imaging the object, a processing device for deriving the conveying situation on the buffer conveying section 8041 based on the image information captured by the camera and performing image registration based on the detection information of the primary inspection device 801 and the image information, so as to enable accurate detection by the secondary inspection device 802. In the case of a central processing device, the various processing devices described above can be integrated together as a separate device to realize the above-mentioned functions, which can be located locally to the system or at a remote location and communicate with the system through various wired, wireless, etc. communication means. It should be understood that there can be a storage device associated with the processing device for storing instructions for the processing device to run to realize the above-mentioned functions. The storage device can be any computer-readable storage medium, such as but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any appropriate combination of the foregoing.

[0071] According to the above example use scenarios, embodiments of the present application provide a two-stage security inspection method, which is shown in Figure 9 . As shown, a two-stage security inspection method 900 according to an embodiment of the present application includes: Figure 9

[0072] Step S901, performing primary inspection on the inspected article 803 on the primary inspection conveying section 8042 of the conveying device by the primary inspection device 801;

[0073] ​Step S902: passing the inspected item considered as non-suspicious after the first-level detection through the release conveying section 8044 of the conveying device to release;

[0074] Step S903: conveying the inspected item considered as suspicious after the first-level detection to the buffer conveying section 8041 of the conveying device, where the buffer conveying section 8041 is used to transport the suspicious inspected item to the second-level detection device 802;

[0075] Step S904: controlling the operation of the buffer conveying section 8041 according to the transportation of the suspicious inspected item on the buffer conveying section 8041 by the control device 806 to buffer the difference between the detection rates of the first-level detection device 801 and the second-level detection device 802;

[0076] Step S905: performing the second-level detection on each suspicious region in the suspicious inspected item by the second-level detection device 802;

[0077] Step S906: passing the inspected item considered as non-suspicious after the second-level detection through the release conveying section 8044 of the conveying device to release; and

[0078] Step S907: conveying the inspected item considered as suspicious after the second-level detection to the inspection conveying section 8045 of the conveying device to undergo further inspection.

[0079] According to the second-level security inspection system and method, the detection of the two-level detection devices can be effectively coordinated by buffering the difference between the detection rates of the first-level detection device and the second-level detection device, and the requirement of pausing other parts of the security inspection system due to the accumulation of detection tasks at the second-level detection device can be prevented, so as to improve the through efficiency and detection efficiency of the entire security inspection system. For example, under the condition of 160 kV voltage and 3 mA current, the second-level XRD detection on each item possibly containing prohibited articles requires about 10 seconds. Assuming that the CT detection alarm rate is 20%, after the cascade second-level XRD detection, the security inspection system as a whole can achieve a through speed of 1800 pieces / hour, and further assuming that the unpacking rate after the XRD detection is 10%, the overall unpacking frequency is 36 pieces / hour, and assuming that the manual unpacking inspection speed is 20 pieces / hour, it can be estimated that about 2 unpacking inspection personnel are required for a single system under the condition of the limit through rate of 1800 pieces / hour. As can be seen, the cascade security inspection system can greatly improve the through efficiency and detection efficiency, and effectively reduce the labor cost.

[0080] The above detailed description of the embodiments of the application has been presented for the purposes of providing a thorough and complete description of the application. However, it is apparent that the application can be practiced without some or all of these specific details. The description of the embodiments is not intended to limit the application to the particular forms disclosed, but rather, it is to serve as an illustrative example of the application. The application is to cover any modifications, equivalents, and alternatives falling within the scope of the application as defined by the appended claims.

[0081] It should be noted that the words "comprise", "comprising", "include", "including" and "includes" in the specification are not used as limiting. The word "an" or "one" preceding an element in the specification does not exclude the presence of more than one of that element. The word "a" or "an" preceding a list of elements does not exclude the presence of more than one of the listed elements.

[0082] Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes and can not have been selected to convey 5 electoral or limiting delineations of the subject application. Thus, the scope of the subject application is not intended to be limited to the specific form set forth herein, but includes all modifications, variations and alternatives falling within the scope of the subject application as defined by the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Claims

1. A dual-stage security inspection system, comprising: a primary inspection device for performing a primary inspection on inspected items on a conveying device, wherein the primary inspection device is a digital radiography (DR) device or a computed tomography (CT) device; a secondary inspection device for performing a secondary inspection on one or more specific regions in inspected items determined as suspicious after the primary inspection, wherein the conveying device comprises a buffer conveying section between the primary inspection device and the secondary inspection device for transporting the suspicious inspected items to the secondary inspection device, wherein the secondary inspection device is an X-ray diffraction (XRD) inspection device; and a control device for controlling operation of the buffer conveying section to buffer a difference between inspection rates of the primary inspection device and the secondary inspection device according to a transportation condition of the suspicious inspected items on the buffer conveying section, wherein the transportation condition of the suspicious inspected items on the buffer conveying section comprises at least one of a number of the suspicious inspected items on the buffer conveying section and a distance between the suspicious inspected items on the buffer conveying section. The buffer conveying section comprises a plurality of cylindrical members independently rotatable, the plurality of cylindrical members are arranged in sequence along a conveying direction, and 2. The dual stage security screening system of claim 1, wherein, the control device selectively controls one or more of the plurality of cylindrical members to rotate or stop rotating according to the transportation condition of the suspicious inspected items on the buffer conveying section. The dual-stage security inspection system further comprises at least one of an imaging device, an optical sensor device and a gravity sensor device to determine the transportation condition of the suspicious inspected items on the buffer conveying section from information obtained by the at least one device.

3. The two-stage security screening system of claim 1 or 2, wherein, The XRD inspection device comprises:

4. The dual stage security screening system of claim 1, wherein, a radiation emitting module for emitting radiation at one or more fan beam planes to the suspicious inspected items; and a detector module for detecting radiation diffracted by the suspicious inspected items and collimated at the one or more fan beam planes, wherein the detector module comprises one or more groups of detectors, each group of detectors corresponding to one of the one or more fan beam planes and configured to detect radiation diffracted by the suspicious inspected items and collimated at the fan beam plane corresponding to the group of detectors. 5.The dual-stage security inspection system of claim 4, wherein each group of detectors comprises one or more detectors, each detector configured to detect radiation diffracted by a specific location in the suspicious inspected items and collimated at an intersection position of a respective pixel element of the detector and the fan beam plane corresponding to the group of detectors in a direction opposite to a corresponding collimating direction. The radiation emitting module comprises:

6. The dual stage security screening system of claim 5, wherein, a radiation source for emitting radiation, wherein the radiation source has a plurality of radiation source focal points in an array, each radiation source focal point being independently controllable to emit radiation; and a front collimator arranged such that radiation from the radiation source is irradiated at the one or more fan beam planes to the suspicious inspected items. ​ 7. The dual stage security screening system of claim 6, wherein, one or more of the plurality of focal points of the radiation sources is selected to emit radiation, wherein the selected focal point of the radiation source is selected according to the one or more specific regions on the suspicious inspected item determined based on the information of the primary inspection, such that at least one of the one or more specific regions is covered by at least one of the one or more fan beam planes.

8. The dual stage security screening system of claim 7, wherein, The one or more specific regions are determined according to a position of a suspicious object in the suspicious inspected item, a position of an interfering object around the suspicious object determined based on the information of the primary inspection.

9. The dual stage security screening system of claim 8, wherein, The one or more detectors include at least one movable detector, the movable detector is independently controllable to move, and one of the at least one movable detector is movable to a position corresponding to one of the at least one specific region.

10. A dual-stage security inspection method, comprising: performing primary inspection on an inspected item on a conveying device by a primary inspection device, wherein the primary inspection device is a digital radiography (DR) device or a computed tomography (CT) device; performing secondary inspection on one or more specific regions in a suspicious inspected item determined as suspicious after the primary inspection by a secondary inspection device, wherein the conveying device includes a buffer conveying section between the primary inspection device and the secondary inspection device for transporting the suspicious inspected item to the secondary inspection device, wherein the secondary inspection device is an X-ray diffraction (XRD) inspection device; and controlling, by a control device, operation of the buffer conveying section to buffer a difference between inspection rates of the primary inspection device and the secondary inspection device according to a transportation condition of the suspicious inspected item on the buffer conveying section, wherein the transportation condition of the suspicious inspected item on the buffer conveying section includes at least one of a number of the suspicious inspected item on the buffer conveying section and a distance between the suspicious inspected items on the buffer conveying section.

11. The two-stage security method of claim 10, wherein, The buffer conveying section includes a plurality of cylindrical members independently rotatable, the plurality of cylindrical members are arranged in sequence along a conveying direction, and The dual-stage security inspection method includes: selectively controlling, by the control device, one or more of the plurality of cylindrical members to rotate or stop rotating according to the transportation condition of the suspicious inspected item on the buffer conveying section.

12. The dual-stage security inspection method of claim 10 or 11, further comprising: determining the transportation condition of the suspicious inspected item on the buffer conveying section from information obtained from at least one of an imaging device, an optical sensor device, and a gravity sensor device.

13. The two-stage security screening method of claim 10, wherein, The XRD inspection includes: emitting, by a radiation emitting module, radiation to the suspicious inspected item in one or more fan beam planes; and detecting, by a detector module, the rays diffracted by and collimated through the suspicious inspected item from the one or more fan beam planes, wherein the detector module comprises one or more groups of detectors, each group of detectors corresponding to one of the one or more fan beam planes and being configured to detect the rays diffracted by and collimated through the suspicious inspected item from the fan beam plane corresponding to the group of detectors.

14. The two-stage security method of claim 13, wherein, Each group of detectors comprises one or more detectors, each detector being configured to detect the rays diffracted by and collimated through a specific location in the suspicious inspected item, the specific location being at an intersection position of a pixel element of the detector with the fan beam plane corresponding to the group of detectors in a direction opposite to the corresponding collimation direction.

15. The dual-stage security inspection method of claim 14, further comprising: emitting, by a ray source in the ray emitting module, the rays, wherein the ray source has an array of a plurality of ray source focal points, each ray source focal point being independently controllable to emit the rays; and and collimating, by a front collimator in the ray emitting module, the rays from the ray source to be incident on the suspicious inspected item at the one or more fan beam planes.

16. The dual-stage security inspection method of claim 15, further comprising selecting one or more ray source focal points of the plurality of ray source focal points to emit the rays according to the one or more specific regions on the suspicious inspected item determined based on the information from the first stage detection, such that at least one of the one or more specific regions is covered by at least one of the one or more fan beam planes.

17. The dual-stage security inspection method of claim 16, wherein the one or more specific regions are determined according to a location of a suspicious object in the suspicious inspected item and a location of an interfering object around the suspicious object determined based on the information from the first stage detection.

18. The two-stage security screening method of claim 17, wherein, the one or more detectors comprise at least one movable detector, the movable detector being independently controllable to move, the dual-stage security inspection method further comprises: moving one of the at least one movable detector to a position corresponding to one of the at least one specific region.

19. A dual-stage security inspection method, comprising: performing, by a first stage inspection device, a first stage inspection on an inspected item on a first stage inspection section of a conveyance device, wherein the first stage inspection device is a digital radiography (DR) device or a computed tomography (CT) device; passing the inspected item that is deemed non-suspicious after the first stage inspection through a release section of the conveyance device for release; passing the inspected item that is deemed suspicious after the first stage inspection to a buffer section of the conveyance device, wherein the buffer section is configured to transport the suspicious inspected item to a second stage inspection device, wherein the second stage inspection device is an X-ray diffraction (XRD) inspection device; controlling, by a control device, operation of the buffer conveyor section to buffer a difference between a detection rate of the primary detection device and a detection rate of the secondary detection device in accordance with a condition of transport of suspicious inspected items on the buffer conveyor section, wherein the condition of transport of suspicious inspected items on the buffer conveyor section comprises at least one of: a number of suspicious inspected items on the buffer conveyor section, a distance between suspicious inspected items on the buffer conveyor section; performing, by the secondary detection device, secondary detection of each suspicious region in the suspicious inspected items; causing an inspected item that is deemed not suspicious following the secondary detection to be released through a release conveyor section of the conveyor device; causing an inspected item that is deemed suspicious following the secondary detection to be conveyed to an inspection conveyor section of the conveyor device to undergo further examination.

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