Multi-energy x-ray baggage inspection apparatus using x-ray energy spectrum analysis

Abstract

The present invention relates to a multi-energy X-ray baggage inspection device using X-ray energy spectrum analysis, the device acquiring an image for each energy band and deriving X-ray spectrum data so as to distinguish organic materials, inorganic materials, mixtures and heavy metals in detail greater than that of conventional distinguishing performance, thereby having improved material discrimination accuracy.

Description

Multi-energy X-ray baggage screening device using X-ray energy spectrum analysis

[0001] The present invention relates to a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis.

[0002] Airports and major government agencies around the world use X-rays to inspect baggage, carry-on items, and packages for security purposes.

[0003] In the case of dual-energy X-ray security screening machines using existing X-rays, a single X-ray source and high / low dual-energy detector are used to estimate the type of material by calculating using only high-energy and low-energy images and the difference between the transmittance value according to the density of each material and the transmittance value according to thickness, so there were only four types of materials that could be distinguished, making it impossible to distinguish the materials required for each organization's work or causing misidentification.

[0004] In addition, since the conventional inspection device uses a method of classifying substances according to the absorption coefficient range based on the single energy image of the X-ray at the time of display, the accuracy of the substance classification result value was low, and there was also a problem that the time and cost required to correct the classification algorithm for each unique substance increased in order to increase the accuracy of the substance classification result value.

[0005] The purpose of the present invention is to solve the problems of the conventional X-ray baggage screening device described above and to provide an X-ray baggage screening device that can distinguish organic substances, inorganic substances, mixtures and compounds, and among them, can accurately classify and separate necessary substances.

[0006] As a means for solving the above problem, a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis may be provided, including a housing, a transport unit configured to transport a settled object through an inspection location, an X-ray irradiation unit configured to irradiate X-rays to the inspection location, an X-ray detection unit provided in an opposite direction from the X-ray irradiation unit with the inspection location as the center, and a calculation unit configured to receive a counting number by energy from the X-ray detection unit, divide the energy range of the X-ray into a plurality, and generate an image in each energy range, wherein the calculation unit compares the image by energy range of each X-ray with a reference attenuation coefficient to determine whether the object is an inorganic or organic object, and if the object is an inorganic object, the type of inorganic object is identified by comparing the image by energy range of each X-ray with the attenuation coefficient of the inorganic object, and if the object is an organic object, the type of organic object is identified by comparing the image by energy range of each X-ray with the attenuation coefficient of the organic object.

[0007] Meanwhile, the operation unit divides the energy range of the X-ray into n initial ranges, and if the target object is not identified by the n energy ranges of the X-ray, the energy range of the X-ray can be further divided.

[0008] Furthermore, when the energy range of the X-ray is further divided, the operation unit can identify the target object by comparing the image acquired for each energy range with the reference attenuation coefficient for each energy range.

[0009] Meanwhile, the operation unit can divide the energy range of each X-ray into two if the target object is not identified by comparing the energy range of n X-rays with the reference attenuation coefficient.

[0010] In addition, if the target object is not identified, the operation unit can divide the energy range of the X-ray multiple times and compare the reference attenuation coefficient in the divided energy range to identify the target object.

[0011] Meanwhile, the X-ray detector may be a photon counting detector.

[0012] Meanwhile, the X-ray irradiation unit may be provided on the lower side of the transport unit, and the X-ray detection unit may be provided on the upper side of the transport unit.

[0013] Meanwhile, the X-ray irradiation unit is composed of multiple units and is provided in at least two directions among the up, down, left, and right directions of the transport unit, and the X-ray detection unit can be provided on the opposite side of the X-ray irradiation unit with the transport unit as the center.

[0014] It may further include a frame that is formed to extend around the inspection position and is configured to fix the X-ray detection unit to the upper side of the inspection position.

[0015] Meanwhile, the X-ray detection unit is composed of multiple units and can be arranged along the frame above the inspection position.

[0016] Meanwhile, the reference attenuation coefficient can be obtained for each energy range of the X-ray for any substance selected from the group of organic and inorganic substances before X-ray irradiation of the target object.

[0017] The multi-energy X-ray baggage screening device using X-ray energy spectrum analysis according to the present invention can obtain images and derive X-ray spectrum data for each energy band, and based on this, can distinguish organic substances, inorganic substances, mixtures, and heavy metals in more detail and accurately, thereby improving the effectiveness and accuracy of the material discrimination function.

[0018] FIG. 1 is a perspective view of a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis, which is one embodiment according to the present disclosure.

[0019] Figure 2 is a partial cutaway perspective view centered on the inspection position in Figure 1.

[0020] Figure 3 is a conceptual diagram showing the area where X-rays are irradiated centered on the inspection location.

[0021] Figures 4a, 4b, 4c and 4d are diagrams showing examples of dividing the x-ray energy band.

[0022] Figure 5 is a flowchart illustrating a method for separating materials in the operation unit.

[0023] Figure 6 is a flowchart illustrating another method of separating materials in the operation unit.

[0024] Figure 7 is a flowchart illustrating additional steps performed when material differentiation is not performed according to the order of Figure 6.

[0025] FIG. 8 is a diagram illustrating an example of an image obtained when the energy band is divided into four in the present disclosure.

[0026] Hereinafter, a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis according to an embodiment of the present invention will be described in detail with reference to the attached drawings. In the description of the embodiments below, the names of each component may be referred to by different names in the art. However, if there is functional similarity and identity between them, even if a modified embodiment is adopted, it can be viewed as an equivalent configuration. In addition, the symbols added to each component are described for the convenience of explanation. However, the illustrated contents in the drawings in which these symbols are described do not limit each component to the scope within the drawings. Similarly, even if an embodiment in which some of the configurations in the drawings are modified is adopted, it can be viewed as an equivalent configuration if there is functional similarity and identity. In addition, if it is recognized as a component that should be included naturally in light of the general level of a technician in the relevant technical field, a description thereof will be omitted.

[0027] Hereinafter, the configuration of a multi-energy X-ray baggage search device using X-ray energy spectrum analysis according to one embodiment of the present disclosure will be described with reference to FIGS. 1 to 3.

[0028] FIG. 1 is a perspective view of a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis, which is one embodiment according to the present disclosure; FIG. 2 is a partial cutaway perspective view centered on an inspection position in FIG. 1; and FIG. 3 is a conceptual diagram illustrating an area where X-rays are irradiated centered on an inspection position.

[0029] Referring to FIGS. 1 to 3, a multi-energy X-ray baggage search device (1) using X-ray energy spectrum analysis according to one embodiment of the present disclosure may be configured to include a housing (10), a transport unit (20), a frame (50), an X-ray irradiation unit (30), an X-ray detection unit (40), and a calculation unit.

[0030] The housing (10) may have a space provided inside so that an object can move and be inspected. The housing (10) may have an X-ray shielding function to prevent X-rays from being irradiated to the outside when X-rays are irradiated by the X-ray irradiation unit (30). As an example, the housing (10) may be configured to include a shielding body or a material capable of shielding X-rays. Meanwhile, the housing (10) illustrated in FIG. 1 is only an example and may be configured in various shapes.

[0031] The transport unit (20) is configured to transport the object inside the housing (10), perform inspection at the inspection location (D), and transport it to the outside. The transport unit (20) may be configured as a conveyor belt, for example.

[0032] A frame (50) may be provided around the inspection location (D) on the inside of the housing (10). The housing (10) may extend upward on both sides of the transport unit (20) and may extend horizontally above the inspection location (D).

[0033] The X-ray detection unit (40) and the X-ray irradiation unit (30) may be provided in opposite directions with the inspection position (D) between them. As an example, the X-ray irradiation unit (30) may be provided on the lower side of the transport unit (20), and the X-ray detection unit (40) may be provided on the frame (50).

[0034] The X-ray irradiation unit (30) is configured to generate X-rays of single energy. The X-rays irradiated from the X-ray irradiation unit (30) pass through the collimator (60), pass through the inspection position (D), and can be detected by the light detection unit (40).

[0035] The X-ray detection unit (40) may be configured as a photon counting detector. The number of photons detected for each energy can be measured. The X-ray detection unit (40) may be configured in multiple numbers on the frame (50), and as an example, may be arranged along the frame (50).

[0036] The calculation unit is configured to be able to distinguish materials based on the values ​​received from the X-ray detection unit (40). A plurality of photon counting detectors can secure spectrum data by counting photons by energy. Thereafter, the detected X-rays are divided into energy ranges, and materials can be distinguished using image images and attenuation coefficients in each energy range. Meanwhile, in the present disclosure, if material distinction is not made using the attenuation coefficient and image images in the divided energy ranges, the calculation unit subdivides the energy ranges through an energy range division process. In each of the divided energy ranges, materials are again distinguished using image images and attenuation coefficients for each material.

[0037] A reference material attenuation coefficient may be stored in advance in the calculation unit. The reference material attenuation coefficient may be an attenuation coefficient that serves as a reference when the calculation unit determines a material. The reference material attenuation coefficient may include an attenuation coefficient for each energy range obtained using a phantom or calculated after X-ray irradiation of actual materials. The reference material attenuation coefficient may be stored for each energy range. In the present disclosure, since the energy range is divided by the 'energy division process', attenuation coefficients for comparison in each energy range may be stored. This process may be calculated and stored for each energy range when the energy range is re-set (e.g., divided) based on the energy-specific coefficient for the target object in the X-ray detector.

[0038] The calculation unit may include a reference inorganic attenuation coefficient and a reference organic attenuation coefficient in the reference material attenuation coefficient. The reference material attenuation coefficient first uses the data and attenuation coefficient acquired by each energy range to distinguish between organic and inorganic substances. Afterwards, if it is distinguished as organic, the detailed type of the organic substance is identified using the reference organic attenuation coefficient. In addition, if it is distinguished as inorganic, the detailed type of the inorganic substance is identified using the reference inorganic attenuation coefficient. Meanwhile, these reference material attenuation coefficients may be used to perform X-ray imaging on a new substance that has not been stored or a substance composed of a new thickness, and the imaging data may be added.

[0039] Meanwhile, although the above-described embodiment has described a single-view configuration in which the X-ray irradiator is configured as one, the baggage search device according to the present disclosure may be modified and applied to a dual-view configuration. When the baggage search device according to the present disclosure is modified to a dual-view configuration, the X-ray irradiators may be configured in multiple numbers. The multiple X-ray irradiators may be selectively installed in two of the four directions of the upper, lower, left, and right directions of the transport section. As an example, the X-ray irradiators may be configured as a pair, and may be installed on the upper and lower sides of the transport section, or on the lower and side sides, or on the upper and side sides, respectively. At this time, the X-ray detection units may be configured in multiple numbers, and may be installed on opposite sides of the X-ray irradiators with respect to the transport section.

[0040] Figures 4a, 4b, 4c and 4d are diagrams showing examples of dividing the x-ray energy band.

[0041] In the following, the explanation will be given on the assumption that X-ray photography has been performed on a target object and spectral data has been acquired from a photon counting detector.

[0042] Referring to FIG. 4a, in the present disclosure, in order to save resources and shorten the judgment time, the energy range of X-rays is first divided into a low energy range (E1) and a high energy range (E2). At this time, an image is generated in the low energy range (E1) and an attenuation coefficient is calculated. In addition, an image is generated in the high energy range (E2) and an attenuation coefficient is calculated. The two acquired attenuation coefficients and the attenuation coefficient of the reference material are compared to determine whether it is organic or inorganic. In addition, if it is determined to be organic or inorganic, a detailed distinction is made as to what material it is. For example, if the target is determined to be organic, the calculation unit determines whether the target is an organic material such as PE or PVC.

[0043] In the present disclosure, when the distinction between materials is not clearly made within the current energy range, the computation unit performs an 'energy range segmentation process'. The energy range segmentation process can be performed by segmenting each energy range, as in the case of dividing from FIG. 4a to FIG. 4b. Referring to FIG. 4b, the energy ranges can be segmented into four, E1, E2, E3, and E4, through the energy range segmentation process. At this time, since each energy range has changed, images for each energy range are regenerated, and the attenuation coefficients of the objects photographed in each energy range are recalculated. In other words, through a single energy range segmentation process, the amount of data that can be compared is doubled. Thereafter, the attenuation coefficients calculated for each energy range are compared with the reference attenuation coefficient through the reference material attenuation coefficient to first determine whether the material is inorganic or organic. If it cannot be determined whether the material is organic or inorganic, or if it cannot be determined which organic or inorganic material it is, the computation unit performs the 'energy range segmentation process' again.

[0044] Afterwards, as shown in Fig. 4c, the energy range is divided into E1 to E8, and an image is regenerated for each energy range, and the attenuation coefficient is also calculated again.

[0045] If the material is not distinguished in the energy range divided as shown in Fig. 4c, the operation unit performs the 'energy range division process' again on the measured X-ray energy spectrum data. As a result, the energy range is divided into 16 energy ranges as shown in Fig. 4d.

[0046] Meanwhile, the energy range division process of the aforementioned operation unit was explained by citing as an example that one energy range is divided into two when divided, but it can be implemented by modifying it to three divisions, four divisions, etc.

[0047] FIG. 5 is a diagram illustrating an example of an image obtained when the energy range in the present disclosure is divided into four.

[0048] Referring to Fig. 5, the computation unit can generate X-ray transmission images in each of four energy ranges. Meanwhile, the computation unit can generate eight images when the energy range is divided into eight, and can generate 16 images when the energy range is further divided. Meanwhile, the number of images generated can be limited within a number set by the user.

[0049] Hereinafter, the operation of a multi-energy X-ray baggage search device using X-ray energy spectrum analysis according to the present disclosure will be described with reference to FIGS. 6 to 8.

[0050] Figure 6 is a flowchart illustrating a method for separating materials in the operation unit.

[0051] Referring to Fig. 6, an X-ray is irradiated to an object transferred to an inspection location (S100). As the X-ray is irradiated to the object, the X-ray detection unit obtains energy spectrum data of the X-rays that have passed through the object (S110). The obtained spectrum data is transmitted to the calculation unit. The calculation unit classifies the spectrum data by energy range (S200). At this time, the spectrum data is divided into preset ranges (S200). Thereafter, using the image generated in each divided energy range and the standard attenuation coefficients of inorganic and organic substances, it is determined whether the object is organic or inorganic (S210). If the object is determined to be organic, it is determined what kind of organic substance it is by comparing it with the attenuation coefficients for each organic substance input in advance in each energy range (S220). At this time, the difference in the density and attenuation coefficient of the material in each energy range is comparatively used to determine what kind of organic substance it is. Similarly, if it is determined to be inorganic, it is determined what kind of inorganic substance it is by comparing it with the attenuation coefficients for each inorganic substance input in advance in each energy range (S230). When the target is determined to be a specific type of organic or inorganic substance, the calculation unit outputs the target determination result (S400).

[0052] Meanwhile, if it is unclear whether the target is organic or inorganic, or if it is unclear which inorganic substance it is, or if it is not yet known which organic substance it is, the calculation unit refines the energy range (S300). After the energy range has been refined, a step may be performed to determine whether the target is organic or inorganic using the image for each energy range, the reference attenuation coefficient, and the calculated attenuation coefficient of the target (S210).

[0053] The energy range segmentation process in the aforementioned computational unit can be repeated repeatedly until the substance is identified. Theoretically, the energy range segmentation process can be performed until the energy range is segmented according to the energy of the photon that can be distinguished by each photon counting detector. However, to prevent resource waste and enable rapid judgment, the user can set the energy range segmentation process to be limited to n times. If the computational unit cannot identify the substance even after segmenting the energy range for the user-set number of times, it can output an indecipherable result value and generate a signal to notify the user.

[0054] Hereinafter, a method for identifying an object in a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis performed by a computation unit according to another embodiment of the present disclosure will be described. This embodiment may also include the same steps as in the aforementioned embodiment, and such configurations will be omitted, with a detailed description of steps that differ.

[0055] Figure 7 is a flowchart illustrating another method of separating materials in the operation unit.

[0056] Referring to Fig. 7, when an X-ray energy spectrum penetrating a target is acquired (S1100), the computation unit divides the energy range into a low-energy range E1 and a high-energy range E2. Thereafter, an image is generated from E1 and E2, and whether the target is organic or inorganic is determined using the standard attenuation coefficients of inorganic and organic substances (S2100). In this step, if it is unclear whether the target is organic or inorganic, a step of dividing the energy range (S3000) may be performed. If the target is determined to be organic, the standard attenuation coefficients for each organic substance are compared in E1 and E2 to determine whether the target is organic (S2300). At this time, when the determination is complete, the determination result of the target is output (S10000). Conversely, if it is impossible to determine whether the target is organic, a step of dividing the energy range (S3000) may be performed.

[0057] If the target is determined to be an inorganic object, the type of inorganic object is determined using the standard attenuation coefficient for each inorganic object in E1 and E2, the calculated attenuation coefficient, and the image for each area (S2200). Once the type of inorganic object has been determined, the target identification result is output (S10000). However, if the type of inorganic object cannot be determined, a step of dividing the energy range (S3000) may be performed.

[0058] Figure 8 is a flowchart illustrating additional steps performed when material differentiation is not performed according to the order of Figure 7.

[0059] In Fig. 8, if it is difficult to identify the target object using the images and attenuation coefficients acquired for each currently divided energy range, the energy range is divided. At this time, each energy range can be divided into two. Thereafter, the operation unit divides the energy range into E1, E2, E3, and E4 according to the energy magnitude (S3000). Thereafter, using the four images generated in each energy range, the four reference attenuation coefficients, and the four calculated attenuation coefficients for the target object, it is determined whether it is an inorganic or organic object (S3100). If it is an organic object, it is determined which organic object it is in the four energy ranges (S3300), and if it is an inorganic object, it is also determined which inorganic object it is in the four energy ranges (S3200). Meanwhile, if the target object is not identified even using the images and attenuation coefficients acquired in the energy ranges divided into four as in Fig. 7, a step of dividing the energy range again can be performed.

[0060] The number of times the steps in FIG. 8 are repeated can be determined based on the number of division steps preset by the user or the width of the minimum energy range.

[0061] As described above, the multi-energy X-ray baggage screening device using X-ray energy spectrum analysis according to the present disclosure can acquire images for each region by dividing the region by energy range, rather than acquiring image energy of the integrated value of simple high / low energy of the conventional method. Therefore, according to the present disclosure, it is possible to acquire an attenuation coefficient and an image for each energy region, rather than a simple dual energy, and thus, in addition to distinguishing four types of substances, namely organic substances, inorganic substances, mixtures, and heavy metals, it is possible to further identify the detailed type of substances within the organic or inorganic range, such as distinguishing between water / gasoline / acetone, iron, and copper, according to the present disclosure.

Claims

1. Housing with X-ray shielding function; A transport unit configured to transport a settled object through an inspection location; An X-ray irradiation unit configured to irradiate X-rays to the above inspection location; An X-ray detection unit provided in the opposite direction to the X-ray irradiation unit centered on the above inspection position; and A calculation unit configured to receive the number of counts by energy from the X-ray detection unit and divide the energy range of the X-ray into multiple ranges to generate an image in each energy range, The above operation unit, By comparing the image and attenuation coefficient acquired for each energy range of the above X-rays with the pre-input standard attenuation coefficient, it is determined whether the target is inorganic or organic. If the above target is an inorganic substance, the type of inorganic substance is identified by comparing the image and attenuation coefficient acquired for each energy range of the above X-ray with the attenuation coefficient of the inorganic substance entered in advance. A multi-energy X-ray baggage screening device that uses X-ray energy spectrum analysis to identify the type of organic matter by comparing the image and attenuation coefficient acquired for each energy range of the X-rays with the attenuation coefficient of the organic matter input in advance when the above target is an organic matter.

2. In paragraph 1, The above operation unit, The energy range of the above X-rays is divided into the initial n, A multi-energy X-ray baggage screening device using X-ray energy spectrum analysis that further divides the energy range of the X-rays when the target object is not identified within the energy range of the n X-rays.

3. In paragraph 2, The above operation unit, A multi-energy X-ray baggage screening device using X-ray energy spectrum analysis that identifies the target object by comparing the image acquired for each energy range with the reference attenuation coefficient in each energy range when the energy range of the X-ray is further divided.

4. In paragraph 3, The above operation unit, A multi-energy X-ray baggage screening device using X-ray energy spectrum analysis that divides the energy range of each X-ray into two when the target object is not identified by comparing the energy range of the n X-rays with the reference attenuation coefficient.

5. In paragraph 4, The above operation unit, If the above object is not identified, A multi-energy X-ray baggage screening device using X-ray energy spectrum analysis that divides the energy range of the X-ray multiple times and identifies the target object by comparing the reference attenuation coefficient in the divided energy range.

6. In paragraph 5, The above X-ray detection unit is a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis, which is a photon counting detector.

7. In paragraph 6, The above X-ray irradiation unit is provided on the lower side of the transport unit, The above X-ray detection unit is a multi-energy X-ray baggage search device using X-ray energy spectrum analysis, which is provided on the opposite side of the above transport unit.

8. In paragraph 6, The above X-ray irradiation unit is composed of multiple parts, It is provided in at least two directions among the up, down, left, and right directions of the above transport unit, The above X-ray detection unit is a multi-energy X-ray baggage search device using X-ray energy spectrum analysis, each of which is provided on the opposite side of the X-ray irradiation unit with the transfer unit as the center.

9. In paragraph 7, A multi-energy X-ray baggage screening device using X-ray energy spectrum analysis, further comprising a frame formed to extend around the inspection location and configured to fix the X-ray detection unit to the opposite side of the X-ray irradiation unit.

10. In paragraph 9, The above X-ray detection unit is composed of multiple parts, A multi-energy X-ray baggage screening device using X-ray energy spectrum analysis arranged along the above frame.

11. In paragraph 6, The above-mentioned reference attenuation coefficient is a multi-energy X-ray baggage screening device using X-ray energy spectrum analysis obtained by the energy range of the X-ray for a material selected from the group of organic and inorganic substances in advance before X-ray irradiation of the target object.

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