X-ray CT inspection system, X-ray CT inspection method and program

Abstract

To provide an X-ray CT inspection system, an X-ray CT inspection method and a program capable of shortening an inspection time, and accurately and quickly responding to sophisticated concealment methods and an increasing number of inspection targets.SOLUTION: An X-ray CT inspection system (1000) comprises: a first X-ray CT unit (100) that acquires first measurement data from a first inspection object; a template registration unit (200) that selects a target range from the first measurement data, and records it as template data; a second X-ray CT unit (400) that inspects a second inspection object, and acquires second measurement data; and a template determination unit (400) that compares the second measurement data with the template data to calculate a similarity, and gives a notification on the inspection result when the similarity is equal to or larger than a threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an X-ray CT inspection system, an X-ray CT inspection method, and a program. [Background technology]

[0002] Conventionally, inspections using X-ray devices have been used at customs inspection sites and the like to find prohibited items such as illegal drugs brought into the country from abroad. X-ray devices irradiate an object to be inspected with X-rays, and image the internal structure of the object to be inspected by the X-ray transmittance distribution, enabling non-contact and non-destructive inspection. Also, X-ray CT (Computed Tomography) devices are used that move the object to be inspected while changing the direction of X-ray irradiation and detection to obtain a three-dimensional image of the internal structure of the object to be inspected (see, for example, Patent Document 1).

[0003] FIG. 13 is a schematic diagram for explaining the inspection of an object by a conventional X-ray CT device. As shown in FIG. 13, the X-ray CT device 1 irradiates and detects X-rays while transporting the object 2 on a belt conveyer 3. More specifically, as shown in FIG. 13(a) to FIG. 13(f), a helical scan is performed in which the object 2 is moved by the belt conveyer 3 inside the slip ring 4 while rotating the slip ring 4 in which an X-ray irradiation unit and a detection unit are arranged in a ring shape. As a result, three-dimensional voxel (volume+pixel) data can be obtained as a captured image while changing the position and direction of X-ray irradiation over time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-084275 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, it may be difficult to identify whether a substance in an object of inspection is an illegal drug by inspection using only X-ray CT scanners. In such cases, inspectors must visually check the object of inspection, select suspicious items, and perform separate inspections to identify the substance. Therefore, it has been difficult to shorten the inspection time with individual inspections using X-ray CT scanners. In addition, in recent years, the methods of concealing illegal drugs have become more sophisticated, and the expansion of cross-border e-commerce has led to a rapid increase in imported cargo and an increase in the number of foreign visitors to Japan. This has made it extremely important to use inspection and inspection equipment to effectively and efficiently crack down on illegal drugs at the border, and there is a growing demand to shorten the inspection time using X-ray CT scanners.

[0006] Therefore, the present invention has been made in consideration of the above-mentioned problems in the conventional technology, and has an object to provide an X-ray CT inspection system, an X-ray CT inspection method, and a program that can shorten the inspection time and accurately and quickly deal with clever concealment methods and an increasing number of objects to be inspected. [Means for solving the problem]

[0007] In order to solve the above problems, the X-ray CT inspection system of the present invention is characterized in comprising a first X-ray CT unit that acquires first measurement data from a first inspection object, a template registration unit that selects a target range from the first measurement data and records it as template data, a second X-ray CT unit that inspects a second inspection object and acquires second measurement data, and a template determination unit that calculates a similarity between cut-out data obtained from the second measurement data and the template data, and notifies the inspection result if the similarity is equal to or greater than a threshold.

[0008] In the X-ray CT inspection system of the present invention, template data is selected and recorded from the first measurement data, and the second measurement data is compared with the template data. If the similarity is equal to or greater than a threshold, the inspection result is notified. This shortens the inspection time and makes it possible to respond accurately and quickly to clever concealment methods and an increasing number of inspection objects.

[0009] In one aspect of the invention, the template and the segmentation each include effective atomic number data and density data.

[0010] In one aspect of the present invention, the template data and the cut-out data are image data that display effective atomic numbers in a first color set and display density in a second color set different from the first color set, and the template determination unit calculates the similarity by comparing these image data with each other.

[0011] In another aspect of the present invention, the template data is two-dimensional voxel data or three-dimensional voxel data.

[0012] In another aspect of the invention, the template determination unit extracts a plurality of pieces of the extracted data from the second measured data at a plurality of sections, and calculates the similarity between each of the plurality of pieces of the extracted data and the template data.

[0013] In addition, in one aspect of the present invention, the target range is a range that includes the detection targets that were included in the first inspection target and target items that were used to conceal or disguise the detection targets.

[0014] In addition, in order to solve the above-mentioned problems, the X-ray CT inspection method of the present invention is characterized by comprising a first measurement process of acquiring first measurement data from a first inspection object, a template registration process of selecting a target range from the first measurement data and recording it as template data, a second measurement process of inspecting a second inspection object to acquire second measurement data, and a template determination process of comparing the second measurement data with the template data to calculate a similarity, and notifying an inspection result if the similarity is equal to or greater than a threshold.

[0015] In order to solve the above problem, the program of the present invention causes a computer to execute a first measurement procedure of acquiring first measurement data from a first inspection object, a template registration procedure of selecting a target range from the first measurement data and recording it as template data, a second measurement procedure of inspecting a second inspection object to acquire second measurement data, and a template determination procedure of comparing the second measurement data with the template data to calculate a similarity and notifying an inspection result if the similarity is equal to or greater than a threshold. Effect of the Invention

[0016] The present invention can provide an X-ray CT inspection system, an X-ray CT inspection method, and a program that can shorten the inspection time and accurately and quickly deal with clever concealment methods and an increasing number of inspection objects. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram illustrating an overview of an X-ray CT inspection system 1000 according to a first embodiment of the present invention. [Diagram 2] 10 is a flowchart outlining an X-ray CT inspection method using the X-ray CT inspection system 1000. [Diagram 3] 3A and 3B are schematic diagrams illustrating the detection of import-restricted items using an X-ray CT inspection system 1000, where FIG. 3A shows the detection in the first measurement process, FIG. 3B shows the template registration process, and FIG. 3C shows the second measurement process and the template judgment process. [Figure 4] 10 is a flowchart illustrating the operations of the first X-ray CT section 100 and the template registration section 200 in a template registration step. [Diagram 5] 13 is a flowchart illustrating the operations of the second X-ray CT section 300 and the template determination section 400 in a template determination step. [Figure 6]6A and 6B are diagrams for explaining a specific example of the template registration process, in which FIG. 6(a) shows three-dimensional voxel data of the first measurement data, FIG. 6(b) shows an example screen display of the measurement data presentation unit 210 and the target range designation unit 220, FIG. 6(c) shows density data in the template data, and FIG. 6(d) shows effective atomic number data in the template data. [Figure 7] 7A and 7B are schematic diagrams for explaining the cutting out of cut data from the second measurement data, where FIG. 7A shows the second measurement data, FIG. 7B shows the cut out in a cross section along the length and width directions (XZ plane), FIG. 7C shows the cut out in a cross section along the horizontal and length directions (XY plane), and FIG. 7D shows the cut out in a cross section along the width and horizontal directions (YZ plane). [Figure 8] 8A to 8C are schematic diagrams illustrating the cut-out data cut out from the second measurement data, where Figures 8(a) to 8(c) each show the cut-out positions, Figures 8(d) to 8(f) each show two-dimensional voxel data cut out from the cut-out positions, and Figures 8(g) to 8(i) show the cut-out data converted into a two-dimensional image. [Figure 9] 11A and 11B are schematic diagrams illustrating calculation of a similarity in a template matching process. [Figure 10] 10A and 10B are schematic diagrams for explaining the cutting out of cut-out data in the second embodiment, in which FIG. 10(a) shows the cutting out in multiple planes obtained by rotating around one axis, FIG. 10(b) shows the cutting out in multiple planes obtained by rotating around two axes, and FIG. 10(c) shows the cutting out in three dimensions. [Figure 11] 11A and 11B are schematic diagrams for explaining the cutting out of data from the inspection object 10 in the second embodiment, in which Figs. 11(a) and 11(b) show the cutting out in multiple planes obtained by rotating around two axes, and Figs. 11(c) and 11(d) show the cutting out in three dimensions. [Figure 12] 12A and 12B are graphs showing template data in the form of histograms according to the third embodiment, where FIG. 12A is a histogram of density data and FIG. 12B is a histogram of effective atomic number. [Figure 13] FIG. 1 is a schematic diagram for explaining an inspection of an object to be inspected by a conventional X-ray CT apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (First embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. FIG. 1 is a schematic diagram for explaining an overview of an X-ray CT inspection system 1000 according to this embodiment. As shown in FIG. 1, the X-ray CT inspection system 1000 includes a first X-ray CT section 100, a template registration section 200, a second X-ray CT section 300, and a template determination section 400. In FIG. 1, the first X-ray CT section 100, the template registration section 200, the second X-ray CT section 300, and the template determination section 400 are shown separately, but in an actual inspection site, one X-ray CT device implements the functions of each section, and each process is performed using the function of each section depending on the situation.

[0019] The first X-ray CT unit 100 and the second X-ray CT unit 300 are X-ray CT devices that irradiate an inspection object with X-rays and measure the transmittance distribution of X-rays to obtain measurement data. The first X-ray CT unit 100 is an X-ray CT device used when a discovery object (first inspection object) is discovered, and the second X-ray CT unit 300 is an X-ray CT device that performs inspection of a new inspection object (second inspection object) by referring to the past discovery object. In FIG. 1, the first X-ray CT unit 100 and the second X-ray CT unit 300 are shown as separate devices, but may be the same X-ray CT device. In addition, the first X-ray CT unit 100 and the second X-ray CT unit 300 may have the same device configuration or different device configurations.

[0020] The measurement data acquired by the first X-ray CT section 100 corresponds to the first measurement data in the present invention, and the measurement data acquired by the second X-ray CT section 300 corresponds to the second measurement data in the present invention. The first X-ray CT section 100 and the second X-ray CT section 300 may be connected to other devices via an electric information communication line or the like so as to be able to communicate information. The content of the data included in the measurement data is not limited, but it is preferable that the measurement data includes density data, which is the spatial density distribution of the test object, and effective atomic number data, which is data expressing the spatial distribution of the elements constituting the test object in terms of effective atomic number.

[0021] The first X-ray CT section 100 in this embodiment includes an effective atomic number data acquisition section 110 and a density data acquisition section 120. The second X-ray CT section 300 in this embodiment includes an effective atomic number data acquisition section 310 and a density data acquisition section 320. In the example shown in FIG. 1, the effective atomic number data acquisition sections 110, 310 and the density data acquisition sections 120, 320 are provided in the first X-ray CT section 100 and the second X-ray CT section 300, respectively, but the effective atomic number data acquisition sections 110, 310 and the density data acquisition sections 120, 320 may be configured by executing a predetermined program in an information processing device other than the X-ray CT device.

[0022] Although the specific configuration of the first X-ray CT unit 100 and the second X-ray CT unit 300 is not limited, it is preferable that they are capable of acquiring three-dimensional voxel data of the test object, and a helical scan type in which measurements are performed while rotating a slip ring is preferable. The first X-ray CT unit 100 and the second X-ray CT unit 300 each include a control unit that controls the driving of the X-ray CT device according to a predetermined program, an information processing unit that processes various types of obtained information according to a predetermined procedure, a recording unit that records various types of information, an information communication unit that transmits various types of information between other units and the outside, and the like (not shown).

[0023] The effective atomic number data acquisition units 110, 310 are units that calculate the effective atomic number in each voxel of the test object from the measurement results of the first X-ray CT unit 100 and the second X-ray CT unit 300, respectively, and acquire effective atomic number data. The effective atomic number data is three-dimensional voxel data in which the effective atomic numbers of all voxels of the test object are arranged three-dimensionally, and is data in which the structure of the test object is associated with the effective atomic number. The specific configuration of the effective atomic number data acquisition units 110, 310 is not limited, and conventionally known X-ray interference methods, refraction contrast methods, etc. can be used.

[0024] The density data acquisition units 120 and 320 are units that calculate the density in each voxel of the object of inspection from the measurement results in the first X-ray CT unit 100 and the second X-ray CT unit 300, respectively, and acquire density data. The density data is three-dimensional voxel data in which the densities of all voxels of the object of inspection are arranged three-dimensionally, and is data in which the structure of the object of inspection is associated with the density. The specific configuration of the density data acquisition unit 120 is not limited, and a calculation method based on the effective atomic number and the absorption coefficient that is conventionally known can be used.

[0025] The template registration unit 200 is a unit that selects the target range of the discovered object from the first measurement data acquired by the first X-ray CT unit 100, and records the data included in the selected range as template data. The template registration unit 200 also includes a measurement data presentation unit 210, a target range designation unit 220, and a template recording unit 230. The template registration unit 200 includes an information processing unit that processes various information, a recording unit that records various information, a display unit that displays various information, an input unit where an operator performs input work, an information communication unit that transmits various information between other units and the outside, and the like (not shown), and each of these units executes a predetermined procedure according to a predetermined program to realize each function. The template registration unit 200 is also connected to other devices via an electric information communication line or the like so as to be able to communicate information.

[0026] The measurement data presentation unit 210 is a unit that acquires the first measurement data acquired by the first X-ray CT unit 100 and presents the first measurement data to the operator using a display unit or the like in a manner according to the input from the input unit. As a more specific example, in response to the input from the operator, the measurement data presentation unit 210 displays the three-dimensional voxel data of the first measurement data as a stereoscopic image, changes the viewpoint position to display the stereoscopic image, displays a cross-sectional image of the stereoscopic image, or changes the cross-sectional position. In addition, when the three-dimensional voxel data of the first measurement data presented by the measurement data presentation unit 210 includes effective atomic number data and density data, a specific effective atomic number and density part may be displayed with a predetermined color. This makes it possible to extract and color-code parts that match the effective atomic number and density of a previously registered illicit drug, making it easier to visually identify suspicious parts.

[0027] The target range designation unit 220 is a part that designates a range (target range) of a discovery target from within the first measurement data presented by the measurement data presentation unit 210. As a more specific example, the target range designation unit 220 selects a partial range of the first measurement data displayed on the display unit in response to an input from an operator. The selected range may be two-dimensional or three-dimensional. The target range designation unit 220 will be described in detail later.

[0028] The template recording unit 230 is a section that records data included in the range selected by the target range designation unit 220 in the first measurement data as template data. A plurality of template data are recorded in the template recording unit 230 for each discovered property. Each template data can be read at any time by the template determination unit 400. Here, the template data becomes two-dimensional voxel data when the template is selected in two dimensions, and becomes three-dimensional voxel data when the template is selected in three dimensions. A histogram may also be used as the template data. The template data will be described in detail later.

[0029] The template determination unit 400 is a part that compares the second measurement data acquired by the second X-ray CT unit 300 with the template data recorded in the template recording unit 230 to calculate a similarity, and notifies the inspection result when the similarity is equal to or greater than a threshold value. The template determination unit 400 also includes a template acquisition unit 410, a template matching unit 420, and an inspection result notification unit 430. The template determination unit 400 includes an information processing unit that processes various information, a recording unit that records various information, a display unit that displays various information, an input unit where an operator performs input work, an information communication unit that transmits various information between other units and the outside, and the like (not shown), and each of these units executes a predetermined procedure according to a predetermined program to realize each function. The template determination unit 400 is also connected to other devices via an electric information communication line or the like so as to be able to communicate information with each other.

[0030] The template acquisition unit 410 is a part that acquires the second measurement data acquired by the second X-ray CT unit 300 and acquires the template data recorded in the template recording unit 230. The template acquisition unit 410 may acquire a single piece of template data or multiple pieces of template data. Furthermore, each time the second X-ray CT unit 300 inspects one second inspection object and acquires one piece of second measurement data, the template acquisition unit 410 may sequentially acquire multiple pieces of template data from the template recording unit 230. Furthermore, when the second X-ray CT unit 300 inspects multiple second inspection objects, the template acquisition unit 410 may acquire multiple pieces of template data all at once from the template recording unit 230.

[0031] The template matching unit 420 is a part that compares the second measurement data acquired by the template acquisition unit 410 with the template data to calculate the similarity. The method of calculating the similarity between the second measurement data and the template data in the template matching unit 420 is not limited. One example is a method of comparing cut-out data cut from the second measurement data at a predetermined cut-out with the template data and calculating the similarity therebetween. Here, the cut-out data is preferably cut at a plurality of different positions or angles in the second measurement data, and it is preferable to compare the cut-out data at all cut-outs with the template data.

[0032] When the template data is a histogram, the template matching unit 420 extracts cut-out data from the three-dimensional voxel data of the second measurement data at a predetermined cut section, converts the information contained in the cut-out data into a histogram, and compares the data. At this time, the histograms of the cut-out data and the template data can be treated as images, so that the similarity can be calculated using a conventionally known image comparison technique.

[0033] When the template data is two-dimensional voxel data, the template matching unit 420 cuts out cut data from the three-dimensional voxel data of the second measurement data at a predetermined cut point where the cut data becomes two-dimensional voxel data, and compares the data. At this time, since both the cut data and the template data are two-dimensional voxel data and can be treated as images, the similarity can be calculated using a conventionally known image comparison technique.

[0034] When the template data is three-dimensional voxel data, the template matching unit 420 compares cut-out data from the three-dimensional voxel data of the template data and the second measurement data at a predetermined cut-out section where the cut-out data becomes two-dimensional voxel data. At this time, since both the cut-out data and the template data are two-dimensional voxel data and can be treated as images, the similarity can be calculated using a conventionally known image comparison technique.

[0035] The inspection result notifying unit 430 is a part that compares the similarity calculated by the template matching unit 420 with a threshold value, and notifies the inspection result when the similarity is equal to or greater than the threshold value. The method of notifying the inspection result by the inspection result notifying unit 430 is not limited, and a conventionally known method such as image display, sound, or lamp lighting can be used. Preferably, the template determination unit 400 includes a display unit that displays the second measurement data and is configured to highlight an area in the second measurement data that has a high similarity to the template data.

[0036] The template data and the cutout data may be image data that displays the effective atomic number in a first color group and displays the density in a second color group different from the first color group. Here, an example of the first color group and the second color group is a color group consisting of shades of a first color and a second color. A more specific example is a color group that uses shades of red as the first color group and shades of yellow as the second color group. Other examples of the first color group and the second color group are a gradation from a first color to a second color and a gradation from a third color to a fourth color. A more specific example is a gradation from red to yellow as the first color group and a gradation from blue to green as the second color group.

[0037] The template determination unit 400 calculates the similarity by comparing image data of the template data and the cut-out data, which include the first and second color groups. Because the template data and the cut-out data are image data that include the first and second color groups, respectively, when the template data and the cut-out data are displayed on the display unit, it becomes easy to visually recognize the presence of the discovery target 30.

[0038] The X-ray CT inspection system 1000 shown in Fig. 1 is realized by a control unit and an information processing unit provided in each unit executing a first measurement process, a template registration process, a second measurement process, and a template judgment process by a program recorded in advance in a recording unit. Each process and procedure will be described in detail later.

[0039] FIG. 2 is a flow chart for explaining an outline of an X-ray CT inspection method using the X-ray CT inspection system 1000. FIG. 3 is a schematic diagram for explaining detection of import-restricted items using the X-ray CT inspection system 1000, in which FIG. 3(a) shows detection in the first measurement step, FIG. 3(b) shows a template registration step, and FIG. 3(c) shows a second measurement step and a template judgment step. An X-ray CT device is provided at each inspection site, and each X-ray CT device has the functions of a first X-ray CT unit 100, a template registration unit 200, a second X-ray CT unit 300, and a template judgment unit 400. In any of the X-ray CT devices, if an operator finds a suspicious object inside an inspection target, the target item 20 is taken out of the inspection target 10 and analyzed. If the analysis results in the target item 20 being found as a detection target 30 such as illicit drugs, the X-ray CT device that found the inspection target 10 becomes the first X-ray CT section 100, and all X-ray CT devices become the second X-ray CT section 300. The inspection process (step S10) in the first X-ray CT section 100 when the detection target 30 is found corresponds to the first measurement process in the present invention.

[0040] In a template registration process in step S11, template data is recorded for the discovery target 30 using the first X-ray CT section 100 and the template registration section 200. Next, in a second measurement process and template determination process in step S12, an examination reflecting the template data is performed using the second X-ray CT section 300 and the template determination section 400. Therefore, after the first discovery, rapid examinations can be performed using the template data in all X-ray CT devices.

[0041] As shown in FIG. 3(a), in the first measurement step, the inspection object 10 is inspected using the first X-ray CT unit 100 to obtain first measurement data. At this time, the effective atomic number data acquisition unit 110 acquires voxel data related to the effective atomic number of the inspection object 10 as effective atomic number data. In addition, the density data acquisition unit 120 acquires voxel data related to the density of the inspection object as density data. The display unit of the measurement data presentation unit 210 displays the effective atomic number and density distribution, and the operator inspects the inspection object 10 (for example, a container such as a cardboard box or suitcase and its contents). If the operator finds a suspected import-controlled item such as an illegal drug, that is, a suspicious item, in the inspection object 10, the suspicious item is removed and confirmed to be an import-controlled item. If it is an illegal drug, an analysis is performed.

[0042] If the confirmation (analysis) reveals that the suspected item is a detection target 30 such as an illicit drug, a template registration process is executed. As shown in Fig. 3(b), in the template registration process, a target range designation unit 220 selects a range including the detection target 30 and the target item 20 used to conceal or disguise the detection target 30 from the first measurement data measured by the first X-ray CT unit 100 as a target range, and the template recording unit 230 records it as template data.

[0043] The detection target 30 does not have to be detected by inspection of the inspection target 10 by the first X-ray CT section 100. In other words, the detection target 30 may be detected in the inspection target 10 by an inspection that does not use the first X-ray CT section 100, for example, an inspection by a drug detection dog. In such a case, the inspection target 10 that has been confirmed to include the detection target 30 is measured by the first X-ray CT section 100 in order to acquire and record template data in a state in which the inspection target 10 includes the detection target 30 and the target article 20. In this case, the first measurement process is performed as a process separate from the inspection of the inspection target 10 to detect the detection target 30.

[0044] After the first detection, as shown in FIG. 3(c), in the second measurement step using the second X-ray CT unit 300, the inspection of the inspection objects 50a, 50b, and 50c is performed sequentially to obtain second measurement data. At this time, the template determination step is performed each time the inspection of each of the inspection objects 50a, 50b, and 50c is completed and second measurement data is obtained. In the template determination step, the template matching unit 420 compares the second measurement data with the template data and calculates the similarity. In addition, the inspection result notification unit 430 notifies the inspection result that the similarity is high when the similarity of the inspection object 50b is equal to or greater than a threshold value, for example. When the similarity is less than the threshold value, the inspection result may not be notified, or a notification may be made that the similarity is low.

[0045] Fig. 4 is a flowchart explaining the operation of the first X-ray CT unit 100 and the template registration unit 200 in the template registration process. As shown in Fig. 4, the template registration process includes a template selection process, a target range designation process, and a recording process.

[0046] In the template selection process of step S21, the operator selects the format of the template to be used using the input unit of the template registration unit 200. Although the selection method is not limited, an example is that the template registration unit 200 displays a list of template formats on a predetermined user interface on the display unit, and the operator selects the template format to be used from the list. Here, the template format refers to the format of data extracted from the voxel data of the first measurement data, and examples include histogram, two-dimensional voxel data, and three-dimensional voxel data.

[0047] Next, in the target range designation step of step S22, the measurement data presentation unit 210 acquires the first measurement data from the first X-ray CT unit 100 and displays the first measurement data on the display unit. The operator also uses the target range designation unit 220 to designate a range of data to be included in the template data from the first measurement data so that the voxel data of the target item 20 and the discovery target 30 is included. It is preferable that the display of the first measurement data on the measurement data presentation unit 210 is associated with the range designation on the target range designation unit 220. The display area of ​​the first measurement data is successively updated in response to the operation on the target range designation unit 220, making it easy for the operator to select the optimal range.

[0048] Next, in the recording step of step S23, data included in the range specified by target range designation unit 220 out of the first measurement data is recorded as template data in template recording unit 230. The recorded template data is voxel data included in the range selected in the target range designation step, extracted in the format of the template selected in the template selection step.

[0049] Fig. 5 is a flowchart explaining the operation of the second X-ray CT section 300 and the template determination section 400 in the template determination step. As shown in Fig. 5, the template determination step includes a template acquisition step, a threshold setting step, a second measurement data acquisition step, a template matching step, a similarity determination step, and an examination result notification step. As described above, before the template determination step is executed, the second X-ray CT section 300 performs an examination of the second examination object and acquires the second measurement data.

[0050] In the template acquisition process of step S31, the template acquisition unit 410 acquires template data to be compared with the second measurement data from the template recording unit 230. Here, the template data to be acquired may be selected by an operator, or may be automatically selected by the template acquisition unit 410. Furthermore, the template data selected may be one or multiple.

[0051] Next, in a threshold setting step S32, a threshold value for the similarity to be used in a subsequent step is set. The threshold value may be set by reading a pre-registered threshold value, or may be set by an operator inputting the threshold value using a predetermined user interface.

[0052] Next, in the second measurement data acquisition process of step S33, the template acquisition unit 410 acquires the second measurement data from the second X-ray CT unit 300. At this time, the second measurement data may be acquired for one second inspection object, or the second measurement data for multiple second inspection objects may be acquired collectively. When multiple pieces of second measurement data are acquired, the subsequent template matching process and threshold determination process are executed for each piece of second measurement data.

[0053] Next, in the template matching process of step S34, the template matching unit 420 compares the acquired second measurement data with the template data to calculate the similarity. Here, since the second measurement data is three-dimensional voxel data targeting the entire second inspection object, the template matching unit 420 cuts out cut-out data from the second measurement data at multiple sections and compares each cut-out data with the template data. The format of the cut-out data is a format that matches the format of the template data, and one example is a two-dimensional cross section. The cutting out of the cut-out data will be described in detail later.

[0054] In addition, the cut-out data and the template data are preferably two-dimensional images in which the effective atomic number data and the density data are color-coded and superimposed. By making the cut-out data and the template data into color-coded two-dimensional images, the similarity can be calculated using a conventionally known image recognition method. In addition, the accuracy of the comparison can be improved compared to calculating the similarity using only the effective atomic number data or the density data.

[0055] Next, in a similarity determination step of step S35, the inspection result notification unit 430 compares the threshold value set in the threshold setting step with the similarity calculated in the template matching step. If there is an area in the second measurement data where the similarity is equal to or greater than the threshold value, the process proceeds to step S36, and if there is no area, the template determination step ends.

[0056] Next, in the inspection result notification step of step S36, the inspection result notification unit 430 notifies the operator of the inspection result that there is a region with a similarity equal to or greater than the threshold. More specifically, for example, in the voxel data of the second inspection target, a two-dimensional image or a three-dimensional image is displayed on the display unit provided in the template determination unit 400 by highlighting, for example, a region with a similarity equal to or greater than the threshold. The template determination unit 400 may record the two-dimensional image or the three-dimensional image with the highlighting added in the recording unit. Note that steps S31, S32, and S33 in the template determination step may be performed in any order as long as they are performed before step S34.

[0057] Fig. 6 is a diagram for explaining a specific example of the template registration process, in which Fig. 6(a) shows three-dimensional voxel data of the first measurement data, Fig. 6(b) shows an example of the screen display of the measurement data presenting unit 210 and the target range designation unit 220, Fig. 6(c) shows density data in the template data, and Fig. 6(d) shows effective atomic number data in the template data. Fig. 6 shows an example in which the inspection target 10 is a carrying case, the target article 20 is a shoe, and the detection target 30 is placed inside the shoe.

[0058] As shown in Fig. 6(a), the measurement data presentation unit 210 can display the three-dimensional voxel data of the first measurement data as an image to present the entire first inspection target to the operator. In this case, the three-dimensional voxel data includes effective atomic number data and density data, which may be displayed in different colors and superimposed on each other. Since the first measurement data is the measurement result of the X-ray CT device, the position and orientation of the target object 20 placed inside the inspection target 10 can also be visually confirmed.

[0059] As shown in FIG. 6(b), the operator performs an operation while visually checking the images displayed by the measurement data presenting unit 210 and the target range designating unit 220, selects the target item 20 including the detection target 30 among the inspection target 10, and records it as template data. As an example, the direction and position of the inspection target 10 are selected to determine the cross-sectional position, and a range is selected so that the target item 20 is included in the cross-sectional position. Here, it is possible to select a range so that only the detection target 30 is included as template data, but it is preferable to include the target item 20 in order to ensure that the detection target 30 can be found when a similar detection target 30 is concealed in a similar item, such as in the case of shotgun-type smuggling. In addition, template data including the target item 20 and template data including only the detection target 30 may be selected and recorded at the same time. Here, the measurement data presenting unit 210 and the target range designating unit 220 display the effective atomic number data and density data in different colors in a superimposed manner, making it easy to visually check the position and shape of the detection target 30 and designate an appropriate range.

[0060] 6(c) and 6(d), the density data and effective atomic number data contained in the template data clarify the positions and shapes of the target article 20 and the discovery target 30 present inside the inspection target 10. Here, in order to facilitate calculation of the similarity in the template matching process, it is preferable to select the cross section and the specified range in the template registration process so that the cross section position and orientation reflect the characteristic shapes of the target article 20 and the discovery target 30.

[0061] FIG. 7 is a schematic diagram for explaining the cutting out of the cut out data from the second measurement data, where FIG. 7(a) shows the second measurement data, FIG. 7(b) shows the cutting out in the cross section (XZ plane) along the length direction and width direction, FIG. 7(c) shows the cutting out in the cross section (XY plane) along the horizontal direction and length direction, and FIG. 7(d) shows the cutting out in the cross section (YZ plane) along the width direction and horizontal direction. FIG. 8 is a schematic diagram for explaining the cut out data cut out from the second measurement data, where FIG. 8(a) to FIG. 8(c) show the cut out positions, FIG. 8(d) to FIG. 8(f) show the two-dimensional voxel data cut out from the cut out positions, and FIG. 8(g) to FIG. 8(i) show the cut out data that has been imaged as a two-dimensional image. Here, the length direction, the horizontal direction, and the width direction are mutually orthogonal directions, and correspond to the x-axis, y-axis, and z-axis in the three-dimensional voxel data of the second measurement data. The cut-out direction (angle) of the inspection object 10 varies depending on whether the cross section is cut out along the length direction, the horizontal direction, the width direction, or a direction other than these. Furthermore, the length direction and the width direction are terms used for convenience based on the length and width of the inspection object 10, and the specific cut-out direction is not limited. Furthermore, the cut-out positions and number are examples and are not limited.

[0062] 7 and 8, cut-out data is extracted from the voxel data of the second measurement data at various positions and angles of the inspection target 10 and the target article 20, and multiple cut-out data are extracted for one inspection target 10. Although Fig. 7 shows an example in which multiple cut-out positions are spaced apart, it is preferable to cut out all two-dimensional voxels in the length, horizontal, and width directions.

[0063] 9 is a schematic diagram for explaining the calculation of similarity in the template matching process. The template matching unit 420 compares two-dimensional images of a plurality of cutout data cut out at a plurality of positions and angles with a two-dimensional image of the template data. At this time, it is preferable to compare the cutout data at each rotation angle with the template data while rotating each cutout data in a two-dimensional plane. It is also preferable to compare each cutout data with the template data that is line-symmetrically inverted.

[0064] As described above, in the X-ray CT inspection system 1000, X-ray CT inspection method, and program of this embodiment, template data is selected and recorded from the first measurement data, and the second measurement data is compared with the template data, and the inspection result is notified when the similarity is equal to or greater than a threshold value, thereby shortening the inspection time and making it possible to accurately and quickly respond to clever concealment methods and an increasing number of inspection objects.

[0065] Second embodiment Next, a second embodiment of the present invention will be described with reference to FIG. 10. Descriptions of contents overlapping with the first embodiment will be omitted. In the first embodiment, an example was shown in which the cut-out data from the second measurement data was cut out in three planes along the axial direction of the voxel data, but in this embodiment, a different cut-out method of the cut-out data is shown. FIG. 10 is a schematic diagram for explaining the cut-out data cut-out according to this embodiment, where FIG. 10(a) shows cut-out in a plurality of rotational planes centered on one axial direction, FIG. 10(b) shows cut-out in a plurality of rotational planes centered on two axial directions, and FIG. 10(c) shows cut-out in a solid.

[0066] 10(a), the plane is rotated around an axis extending in the vertical direction in the figure, and cut-out data is cut out on the plane at each position. By using cut-out data on multiple planes obtained by rotating around one axis, it becomes possible to satisfactorily compare the similarity between the two even if the orientation of the target object 20 in the inspection target 10 is tilted in a direction different from that of the template data.

[0067] 10(b), the plane is rotated around an axis extending in the vertical direction and an axis extending in the horizontal direction in the figure, and cut-out data is cut out for each plane. By using cut-out data for multiple planes obtained by rotating around two axes, it becomes possible to more effectively compare the similarity between the two even if the orientation of the target object 20 in the inspection target 10 is tilted in a direction different from that of the template data.

[0068] In the example shown in Fig. 10(c), cut-out data is cut out in a three-dimensional shape from a part of the second measurement data. In this case, it is preferable that the template data is also three-dimensional voxel data of a three-dimensional shape selected from a part of the first measurement data and recorded. In addition, since the template data and the cut-out data are three-dimensional voxel data, the similarity of the three-dimensional shape is calculated in the template matching process. By using the three-dimensional cut-out data, the accuracy of the similarity can be improved.

[0069] 10(a) and 10(b) show cutouts in a plurality of planes obtained by rotating around one axis or two axes, but the number of axes around which the rotation is centered may be three or more. Also, in FIG. 10(c), a spherical shape is shown as the solid to be cut out, but the solid may be cut out in a polyhedral shape, a cubic shape, a cylindrical shape, or the like. Also, cutouts in a solid and cutouts in a rotation plane may be combined, and cutouts in three planes shown in the first embodiment may be combined.

[0070] Fig. 11 is a schematic diagram for explaining the cutting out of cut out data from the inspection object 10 in this embodiment, Fig. 11(a) and Fig. 11(b) show the cutting out in a plurality of planes obtained by rotating around two axes. Fig. 11(c) and Fig. 11(d) show the cutting out in a three-dimensional form. Fig. 11 shows only the cutting out at a predetermined position of the inspection object 10, but it is preferable to cut out similar cut out data at a plurality of positions within the inspection object 10. Note that the cutting out in a plurality of planes obtained by rotating around one or two axes may be performed on the entire inspection object 10.

[0071] Third embodiment Next, a third embodiment of the present invention will be described with reference to FIG. 12. Descriptions of contents overlapping with the first embodiment will be omitted. In the first embodiment, an example was shown in which two-dimensional voxel data or three-dimensional voxel data is used as template data, but in this embodiment, an example is shown in which a histogram of the first measurement data is used. FIG. 12 is a graph showing template data in a histogram according to this embodiment, where FIG. 12(a) is a histogram of density data, and FIG. 12(b) is a histogram of effective atomic number.

[0072] In Fig. 12(a), the horizontal axis indicates density, and the vertical axis indicates the number of voxels counted. In Fig. 12(b), the horizontal axis indicates effective atomic number, and the vertical axis indicates the number of voxels counted. In this embodiment, the effective atomic numbers and densities of voxels included in the range selected in the target range designation step are counted to create a histogram. Fig. 12(a) shows an example in which 60 voxels with a density class interval of 0.4 are counted. Also, Fig. 12(b) shows an example in which 160 voxels with an effective atomic number class interval of 10 are counted.

[0073] When a histogram is used as the template data, the effective atomic number and density of the voxels contained in each of the cut out data are counted to create a histogram. In the template matching process, the histograms of the template data and the cut out data are visualized to calculate the similarity between the two. Since the histogram lacks the amount of shape and structure information compared to two-dimensional voxel data or three-dimensional voxel data, the accuracy of the similarity is not high, but the amount of calculation required to compare the two can be reduced and the similarity can be calculated quickly.

[0074] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. Descriptions of contents overlapping with the first embodiment will be omitted. In the third embodiment, an example was shown in which histograms were used as template data and cutout data, but in this embodiment, an example is shown in which voxel data and histograms are used in combination.

[0075] In this embodiment, a template matching process is first performed using template data of a histogram. Specifically, the similarity between the template data and all the cutout data obtained when inspecting the inspection target 10 is calculated, and cutout data having a similarity equal to or greater than a first threshold is extracted. Next, a template matching process is performed using template data of two-dimensional or three-dimensional voxel data. Specifically, the similarity between the extracted cutout data and template data of two-dimensional or three-dimensional voxel data is calculated, and if cutout data having a similarity equal to or greater than a second threshold is present, it is determined that the inspection target 10 contains the discovery target 30. This makes it possible to achieve both rapid screening using a histogram and accurate inspection using voxel data, and to quickly and accurately notify the presence of the discovery target 30.

[0076] Furthermore, it is preferable that the template matching step using histograms uses three-dimensional cutouts, and the template matching step using voxel data uses the two-dimensional cutouts used in the first or second embodiment.

[0077] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. For example, although the above-described embodiments are directed to import-restricted items, the present invention may also be directed to export-restricted items. [Explanation of symbols]

[0078] 1000…X-ray CT inspection system 100...1st X-ray CT section 110...Effective atomic number data acquisition section 120…Density data acquisition section 200…Template registration section 210…Measurement data presentation section 220...Target range specification section 230…Template recording section 300…Second X-ray CT section 310...Effective atomic number data acquisition section 320…Density data acquisition section 400…Template judgement section 410…Template Acquisition Department 420: Template matching section 430…Test Result Notification Department 10, 50a, 50b, 50c…Target of inspection 20. Target items 30…Discovery target

Claims

1. a first X-ray CT unit that acquires first measurement data from a first inspection object; a template registration unit that selects a target range from the first measurement data and records it as template data; a second X-ray CT unit that inspects a second inspection object and obtains second measurement data; a template determination unit that calculates a similarity between the extracted data obtained from the second measurement data and the template data, and notifies an inspection result when the similarity is equal to or greater than a threshold; Equipped with An X-ray CT inspection system characterized in that the target range is a range that includes a detection target contained in the first inspection target and a target item used to conceal or disguise the detection target and that is present inside the first inspection target.

2. 2. The X-ray CT inspection system according to claim 1, The X-ray CT inspection system is characterized in that the object to be detected is an import-controlled item or an export-controlled item.

3. The X-ray CT inspection system according to claim 1, the first measurement data is three-dimensional voxel data; 2. An X-ray CT inspection system according to claim 1, wherein the template data and the cut-out data are two-dimensional voxel data.

4. 4. The X-ray CT inspection system according to claim 3, The template determination unit extracts a plurality of pieces of cut data from the second measurement data, which is three-dimensional voxel data, at a plurality of sections, and calculates the similarity between each of the plurality of cut data and the template data.

5. 5. The X-ray CT inspection system according to claim 4, An X-ray CT inspection system, wherein the multiple cut sections are multiple planes or multiple rotational planes that are parallel to each other.

6. 6. An X-ray CT inspection system according to claim 1, 11. An X-ray CT inspection system, wherein the template data and the cut-out data each include effective atomic number data and density data.

7. 7. The X-ray CT inspection system according to claim 6, the template data and the cut-out data are image data that respectively display effective atomic numbers in a first color set and density in a second color set different from the first color set, The X-ray CT inspection system is characterized in that the template determination unit calculates the similarity by comparing these image data with each other.

8. a first measurement step of acquiring first measurement data from a first test object; a template registration step of selecting a target range from the first measurement data and recording it as template data; a second measurement step of inspecting a second inspection object to obtain second measurement data; a template determination step of calculating a similarity between the second measurement data and the template data, and notifying an inspection result when the similarity is equal to or greater than a threshold value; An X-ray CT inspection method, characterized in that the target range is a range that includes a detection target contained in the first inspection target and a target item used to conceal or disguise the detection target and that is present inside the first inspection target.

9. On the computer, a first measurement procedure for acquiring first measurement data from a first test object; a template registration step of selecting a target range from the first measurement data and recording it as template data; a second measurement step of inspecting a second inspection object to obtain second measurement data; a template determination procedure for calculating a similarity between the second measurement data and the template data, and notifying an inspection result when the similarity is equal to or greater than a threshold, A program in which the target range includes detection targets contained in the first inspection target and target items used to conceal or disguise the detection targets and that are present inside the first inspection target.

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