Multi-energy imaging system and method

Abstract

A multi-energy imaging system and method. The multi-energy imaging system comprises: a multi-energy spectral radiation source (10) configured to generate at least one of a plurality of types of ray radiation, the plurality of types of ray radiation having energy spectra with different maximum energies; a multi-energy spectral detector (20) capable of acquiring at least one of a plurality of energy components in the energy spectrum of the ray radiation; and a processor (30) in signal connection with the multi-energy spectral radiation source (10) and the multi-energy spectral detector (20) and configured to obtain energy spectral image data of at least two coordination modes between the plurality of types of ray radiation that have passed through an inspected object and the plurality of energy components.

Description

Multi-energy imaging systems and methods

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202411997309.2, filed on December 31, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to the field of radiation imaging, and more particularly to a multi-energy imaging system and method. Background Technology

[0004] In some technologies related to transmission imaging security inspection equipment, a combination of a dual-energy X-ray source and an energy spectrum integrating detector is employed. This dual-energy X-ray source emits two types of bremsstrahlung continuous spectrum X-rays with different maximum energies, while the energy spectrum integrating detector outputs signals that are the result of integrating the polychromatic photon signals of the two highest-energy rays, respectively, reflecting the average attenuation effect of the two highest-energy rays after passing through an object. Thus, by utilizing the difference in the attenuation coefficients of matter for X-rays of different energies, material discrimination is achieved. Summary of the Invention

[0005] In one aspect of this disclosure, a multi-energy imaging system is provided, comprising:

[0006] A multi-spectral radiation source is configured to produce at least one of a variety of radiations, which have different maximum energies.

[0007] A multi-spectral detector is capable of obtaining at least one of multiple energy components in the energy spectrum of X-ray radiation; and

[0008] The processor, connected to a multi-spectral radiation source and a multi-spectral detector, is configured to acquire spectral image data of at least two combinations of multiple ray radiations and multiple energy components passing through the object under inspection.

[0009] In some embodiments, the processor is configured to perform image fusion on energy spectrum image data with at least two different coordination modes.

[0010] In some embodiments, the processor is configured to identify substances based on energy spectrum image data of at least two coordination modes and to color them according to the identification results.

[0011] In some embodiments, the multiple radiations include at least one radiation having an energy spectrum with a maximum energy of less than or equal to 1 MeV and at least one radiation having an energy spectrum with a maximum energy of greater than 1 MeV.

[0012] In some embodiments, the multi-energy spectrum radiation source includes at least one of a linear accelerator, an electron induction accelerator, and a multi-ray source. In some embodiments, the multi-energy imaging system further includes:

[0013] A filter, located at the output of a multi-spectral radiation source, is configured to filter out at least a portion of the overlapping energy spectra of multiple types of radiation.

[0014] In some embodiments, the multi-spectral detector includes at least one of a multi-layer structure detector and a detector that directly measures the intensity of the output signal.

[0015] In some embodiments, the processor is configured to switch between multiple scanning modes based on at least one of the type of object being inspected, the inspection scenario, and the scanning area, wherein each scanning mode differs from the other scanning modes at least in the combination of pulses emitted by the multi-spectral radiation source in each cycle.

[0016] In some embodiments, the multiple radiations include a first radiation with a first maximum energy spectrum, a second radiation with a second maximum energy spectrum, and a third radiation with a third maximum energy spectrum, wherein the first maximum energy is less than or equal to 1 MeV, the second maximum energy and the third maximum energy are both greater than 1 MeV, and the third maximum energy is greater than the second maximum energy.

[0017] In some embodiments, the multiple scanning modes include at least two of a first scanning mode, a second scanning mode, a third scanning mode, and a fourth scanning mode;

[0018] The processor is configured as follows:

[0019] In the first scanning mode, the multi-energy spectrum radiation source emits a first pulse combination in each cycle, the first pulse combination including only at least one pulse of the first ray radiation;

[0020] In the second scanning mode, the multi-energy spectrum radiation source emits a second pulse combination in each cycle, the second pulse combination including at least one pulse of second-ray radiation and at least one pulse of third-ray radiation;

[0021] In the third scanning mode, the multi-energy spectrum radiation source emits a third pulse combination in each cycle, the third pulse combination including at least one pulse of second radiation and at least one pulse of first radiation.

[0022] In the fourth scanning mode, the multi-energy spectrum radiation source emits a fourth pulse combination in each cycle, the fourth pulse combination including at least one pulse of the first radiation, at least one pulse of the second radiation, and at least one pulse of the third radiation.

[0023] In some embodiments, the multiple energy components include a first energy component and a second energy component, wherein the average energy of the first energy component is less than the average energy of the second energy component.

[0024] The processor is configured as follows:

[0025] Obtain energy spectrum image data of at least two combinations between at least one of the first, second, and third radiations passing through the object under inspection and at least one of the first and second energy components, and identify the substance based on the energy spectrum image data of at least two combinations.

[0026] In the first scanning mode, the multi-energy spectrum detector obtains the first and second energy components in the energy spectrum of the first ray radiation.

[0027] In the second scanning mode, the multi-energy spectrum detector is made to obtain the second energy component in the energy spectrum of the second and third radiation, or the multi-energy spectrum detector is made to obtain the first and second energy components in the energy spectrum of the second and third radiation.

[0028] In the third scanning mode, the multi-energy spectrum detector is made to obtain the second energy component in the energy spectrum of the first and second radiations, or the multi-energy spectrum detector is made to obtain the first and second energy components in the energy spectrum of the first and second radiations.

[0029] In the fourth scanning mode, the multi-energy spectrum detector is enabled to obtain the second energy component in the energy spectrum of the first, second, and third radiation, or the multi-energy spectrum detector is enabled to obtain the first and second energy components in the energy spectrum of the first, second, and third radiation.

[0030] In some embodiments, the object under inspection includes a truck having a cab area and a cargo box area, and the processor is configured to:

[0031] The multi-spectral radiation source can scan the cab area using either the first or third scanning mode, or it can be configured not to scan the cab area.

[0032] The multi-spectral radiation source is used to scan the cargo compartment area using either the second or fourth scanning mode.

[0033] In some embodiments, the object being inspected includes a bus, and the processor is configured to:

[0034] The multi-spectral radiation source can perform a full vehicle scan of the bus using either the first or third scanning mode, or it can be configured not to scan the entire bus.

[0035] In one aspect of this disclosure, a multi-energy imaging method according to the aforementioned multi-energy imaging system is provided, comprising:

[0036] Obtain energy spectrum image data of at least two coordination modes between multiple types of radiation and multiple energy components passing through the object under inspection.

[0037] In some embodiments, the multi-energy imaging method further includes:

[0038] Image fusion is performed on energy spectrum image data with at least two coordination modes.

[0039] In some embodiments, the multi-energy imaging method further includes:

[0040] Material identification is performed based on energy spectrum image data of at least two coordination modes, and coloring is performed based on the identification results.

[0041] In some embodiments, the multiple radiations include at least one radiation having an energy spectrum with a maximum energy of less than or equal to 1 MeV and at least one radiation having an energy spectrum with a maximum energy of greater than 1 MeV.

[0042] In some embodiments, the multi-energy imaging method further includes:

[0043] The system switches between multiple scanning modes depending on the type of object being inspected, the inspection scenario, and at least one of the scanning areas. Each scanning mode differs from the other scanning modes at least in the combination of pulses emitted by the multi-spectral radiation source in each cycle.

[0044] In some embodiments, the multiple radiations include a first radiation with a first maximum energy spectrum, a second radiation with a second maximum energy spectrum, and a third radiation with a third maximum energy spectrum, wherein the first maximum energy is less than or equal to 1 MeV, the second maximum energy and the third maximum energy are both greater than 1 MeV, and the third maximum energy is greater than the second maximum energy; the multiple scanning modes include at least two of a first scanning mode, a second scanning mode, a third scanning mode, and a fourth scanning mode;

[0045] Multi-energy imaging methods also include:

[0046] In the first scanning mode, the multi-energy spectrum radiation source emits a first pulse combination in each cycle, the first pulse combination including only at least one pulse of the first ray radiation;

[0047] In the second scanning mode, the multi-energy spectrum radiation source emits a second pulse combination in each cycle, the second pulse combination including at least one pulse of second-ray radiation and at least one pulse of third-ray radiation;

[0048] In the third scanning mode, the multi-energy spectrum radiation source emits a third pulse combination in each cycle, the third pulse combination including at least one pulse of second radiation and at least one pulse of first radiation.

[0049] In the fourth scanning mode, the multi-energy spectrum radiation source emits a fourth pulse combination in each cycle, the fourth pulse combination including at least one pulse of the first radiation, at least one pulse of the second radiation, and at least one pulse of the third radiation.

[0050] In some embodiments, the multiple energy components include a first energy component and a second energy component, wherein the average energy of the first energy component is less than the average energy of the second energy component.

[0051] The steps for obtaining energy spectrum image data of at least two coordination modes between multiple types of X-ray radiation and multiple energy components passing through the object under examination include:

[0052] Obtain energy spectrum image data of at least two coordination modes between at least one of the first, second, and third radiations passing through the object under inspection and at least one of the first and second energy components;

[0053] Multi-energy imaging methods also include:

[0054] Substance identification based on energy spectrum image data of at least two coordination modes;

[0055] In the first scanning mode, the multi-energy spectrum detector obtains the first and second energy components in the energy spectrum of the first ray radiation.

[0056] In the second scanning mode, the multi-energy spectrum detector is made to obtain the second energy component in the energy spectrum of the second and third radiation, or the multi-energy spectrum detector is made to obtain the first and second energy components in the energy spectrum of the second and third radiation.

[0057] In the third scanning mode, the multi-energy spectrum detector is made to obtain the second energy component in the energy spectrum of the first and second radiations, or the multi-energy spectrum detector is made to obtain the first and second energy components in the energy spectrum of the first and second radiations.

[0058] In the fourth scanning mode, the multi-energy spectrum detector is enabled to obtain the second energy component in the energy spectrum of the first, second, and third radiation, or the multi-energy spectrum detector is enabled to obtain the first and second energy components in the energy spectrum of the first, second, and third radiation.

[0059] In some embodiments, the object to be inspected includes a truck having a cab area and a cargo box area;

[0060] Multi-energy imaging methods also include:

[0061] The multi-spectral radiation source can scan the cab area using either the first or third scanning mode, or it can be configured not to scan the cab area.

[0062] The multi-spectral radiation source is used to scan the cargo compartment area using either the second or fourth scanning mode.

[0063] In some embodiments, the object to be inspected includes a passenger vehicle;

[0064] Multi-energy imaging methods also include:

[0065] The multi-spectral radiation source can perform a full vehicle scan of the bus using either the first or third scanning mode, or it can be configured not to scan the entire bus. Attached Figure Description

[0066] The accompanying drawings, which form part of this specification, illustrate embodiments of this disclosure and, together with the specification, serve to explain the principles of this disclosure.

[0067] This disclosure will become clearer with reference to the accompanying drawings and the following detailed description, wherein:

[0068] Figure 1 is a schematic diagram of the structure of some embodiments of the multi-energy imaging system according to the present disclosure;

[0069] Figure 2 is a schematic diagram of the operation of a multi-spectral radiation source with multiple accelerator tubes in some embodiments of the multi-energy imaging system according to the present disclosure.

[0070] Figure 3 is a schematic diagram of the operation of a multi-energy spectrum radiation source with a single accelerator tube and a control electron gun in some embodiments of the multi-energy imaging system according to the present disclosure.

[0071] Figure 4A is a schematic diagram of the operation of a multi-energy spectrum radiation source with two accelerators in some embodiments of the multi-energy imaging system according to the present disclosure.

[0072] Figure 4B is a schematic diagram of the operation of a multi-energy spectrum radiation source with an accelerator and an X-ray machine in some embodiments of the multi-energy imaging system according to the present disclosure.

[0073] Figure 5 is a structural schematic diagram of some other embodiments of the multi-energy imaging system according to the present disclosure;

[0074] Figures 6A and 6B are schematic diagrams illustrating two examples of first pulse combinations emitted by a multi-energy spectrum radiation source in the first scanning mode, according to some embodiments of the multi-energy imaging system of the present disclosure.

[0075] Figures 7A and 7B are schematic diagrams illustrating examples of two combinations of second pulses emitted by a multi-spectral radiation source in a second scanning mode according to some embodiments of the multi-energy imaging system of the present disclosure.

[0076] Figures 8A and 8B are schematic diagrams illustrating examples of two combinations of third pulses emitted by a multi-spectral radiation source in the third scanning mode according to some embodiments of the multi-energy imaging system of the present disclosure.

[0077] Figures 9A, 9B, 9C, 9D, 9E and 9F are schematic diagrams illustrating four examples of fourth pulse combinations emitted by a multi-spectral radiation source in a fourth scanning mode according to some embodiments of the multi-energy imaging system of the present disclosure.

[0078] Figures 10A, 10B, 10C, 10D and 10E are schematic diagrams of vehicle-area scanning and detector acquisition in a truck inspection scenario according to some embodiments of the multi-energy imaging system of this disclosure.

[0079] Figures 11A and 11B are schematic diagrams of scanning and detector acquisition of a bus in a bus inspection scenario according to some embodiments of the multi-energy imaging system of this disclosure.

[0080] It should be understood that the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Furthermore, the same or similar reference numerals denote the same or similar components. Detailed Implementation

[0081] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit the present disclosure or its application or use. The present disclosure may be implemented in many different forms and is not limited to the embodiments herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0082] The terms "first," "second," and similar words used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Words such as "including" or "contains" mean that the element preceding the word encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well. Terms such as "above," "below," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, this relative positional relationship may also change accordingly.

[0083] In this disclosure, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may be not directly connected to the other devices but have an intermediary device.

[0084] All terms used in this disclosure (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as a dictionary, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or highly formalized meaning, unless expressly defined herein.

[0085] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0086] In some technologies related to transmission imaging security inspection equipment, a combination of a dual-energy X-ray source and an energy spectrum integrating detector is employed. This dual-energy X-ray source emits two types of bremsstrahlung continuous spectrum X-rays with different maximum energies, while the energy spectrum integrating detector outputs signals that are the result of integrating the polychromatic photon signals of the two highest-energy rays, respectively, reflecting the average attenuation effect of the two highest-energy rays after passing through an object. In this way, material discrimination is achieved by utilizing the difference in attenuation coefficients of materials under different energy X-rays.

[0087] Research has revealed some applicability issues with these related technologies in terms of imaging performance and material identification. Regarding imaging performance, MeV-level dual-energy X-rays can penetrate heavy cargo and high-Z (high atomic number) materials, making them more suitable for large container cargo inspection applications. However, for imaging thinner materials, the resulting images have lower contrast and are prone to detail loss. Organic materials such as drugs, explosives, and banknotes, due to their low atomic numbers, are easily missed. This is reflected in the relatively poor typical value of MeV-level high-energy imaging systems in terms of spatial wire detection capability (WD).

[0088] In terms of material identification, MeV-level dual-energy X-rays perform well in identifying thicker materials. However, at thinner thicknesses, the detection sensitivity is poor, leading to inaccurate identification of different materials and hindering the system's ability to achieve intelligent identification and suspect alarm.

[0089] In addition, for scenarios requiring cab scanning, dual-energy X-ray sources can only use high-energy scanning for the vehicle cab, which requires the driver to leave the vehicle in advance, affecting inspection efficiency to some extent; alternatively, a low-energy X-ray machine can be added for scanning, but this will increase system complexity and cost.

[0090] In view of this, embodiments of the present disclosure provide a multi-energy imaging system and method that can improve adaptability to the subject being examined.

[0091] Figure 1 is a schematic diagram of the structure of some embodiments of the multi-energy imaging system according to the present disclosure. Referring to Figure 1, an embodiment of the present disclosure provides a multi-energy imaging system, including: a multi-spectral radiation source 10, a multi-spectral detector 20, and a processor 30. The multi-spectral radiation source 10 is configured to generate at least one of a variety of radiations. Here, the multi-spectral radiation source 10 is capable of generating a variety of radiations, and can generate some or all of the various radiations according to a received control signal.

[0092] Multiple types of radiation have energy spectra with different maximum energies. Here, the energy spectrum of radiation represents the continuous distribution of photon energy, which can include the bremsstrahlung continuous spectrum, and the maximum energy can be the maximum photon energy in the bremsstrahlung continuous spectrum. In Figure 1, the dashed lines with arrows represent the radiation emitted by the multi-energy spectrum radiation source 10 passing through the object under inspection 4 and being received by the multi-energy spectrum detector 20.

[0093] The multi-energy spectrum detector 20 is capable of acquiring at least one of multiple energy components in the energy spectrum of X-ray radiation. Here, the multi-energy spectrum detector 20 can acquire multiple energy components in the energy spectrum of X-ray radiation, including acquiring some or all of the multiple energy components. Taking a dual-energy spectrum integrating detector as an example, this multi-energy spectrum detector 20 can acquire two energy components in the energy spectrum of X-ray radiation. These two energy components have different average energies and can be referred to as the low-energy component and the high-energy component, respectively. The average energies of the low-energy component and the high-energy component can be obtained by dividing the total photon energy deposited by the low-energy detection element and the high-energy detection element in the dual-energy spectrum integrating detector by the number of photons deposited.

[0094] The energy spectrum can contain multiple energy components corresponding to different energy ranges, and the multi-energy spectrum detector 20 can be designed to simultaneously acquire multiple energy components or selectively acquire at least one of multiple energy components, and be able to distinguish different energy components. For the bremsstrahlung continuum, the multi-energy spectrum detector 20 can simultaneously acquire multiple energy components in the bremsstrahlung continuum or selectively acquire at least one energy component in the bremsstrahlung continuum.

[0095] The processor 30 is signal-connected to the multi-spectral radiation source 10 and the multi-spectral detector 20, and is configured to acquire energy spectrum image data of at least two combinations of multiple X-ray radiations and multiple energy components passing through the object under inspection.

[0096] The processor 30 may be implemented, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that may be used, without limitation, include: microprocessors, microcontrollers, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), etc. The processor 30 may be signal-connected to the multi-spectral radiation source 10 and the multi-spectral detector 20 via wired or wireless communication.

[0097] When scanning and imaging the object under inspection using the multi-energy spectrum radiation source 10, multiple radiation sources can be combined with the multi-energy spectrum detector 20 to detect multiple energy components. This allows for various combinations, such as two or more radiation sources combined with the detection of one energy component, or one radiation source combined with the detection of two or more energy components, or even more combinations of two or more radiation sources combined with the detection of two or more energy components. This allows for obtaining energy spectrum image data from at least two different combinations in a single scan. The energy spectrum image data from various combinations can reflect richer feature information about the object under inspection, which is beneficial for subsequent operations such as image processing, material identification, and analysis, effectively improving the adaptability of imaging the object under inspection.

[0098] Based on this, the processor can be configured to perform image fusion on energy spectrum image data with at least two different combinations. By fusing energy spectrum image data with at least two different combinations, the fused image can reflect richer feature information of the inspected object, improving imaging performance and thus effectively enhancing the imaging system's adaptability to imaging the inspected object.

[0099] Image fusion algorithms for at least two different energy spectrum image data combinations can be implemented using traditional computer image processing algorithms or deep learning algorithms. For example, traditional computer image processing algorithms can use the ORB (Oriented Fast and Rotated BRIEF) method or the SIFT (Scale Invariant Feature Transform) method for keypoint detection, and the BF (Brute Force) algorithm for feature matching. Finally, weights are assigned and fused based on the characteristics of the image regions.

[0100] Image fusion based on deep learning algorithms can employ supervised or unsupervised methods. Supervised algorithms use high-dose or oversampled images as ground truth image samples during model training. The fusion model extracts deep features using an autoencoder and fuses multi-scale features using a Spatial Transformer (ST). The ST fusion block consists of a CNN and a Transformer branch, capturing local and long-range features respectively. The fusion model can be evaluated using a Generative Adversarial Network (GAN). By alternately training a generative model and a discriminative model, the network optimizes itself to reach Nash equilibrium, thus achieving the optimal fusion effect.

[0101] Unsupervised algorithms can be implemented using information conservation measures. Considering the inconsistency of information contained in different source images, information metric can be estimated by extracting shallow features (texture, local shape, etc.) and deep features (content, spatial structure, etc.). During training, the final loss function is obtained based on the information conservation weights. Feature-level image fusion extracts feature information from source images, such as the edges and contours of the object being inspected, and then analyzes, processes, and integrates this feature information to obtain fused image features. The accuracy of target recognition using the fused features is significantly higher than that of the original image.

[0102] In some embodiments, the processor 30 is configured to identify substances based on energy spectrum image data of at least two coordination modes, and to color the data based on the identification results. This coloring can be applied to a fused image after image fusion based on the identification results, or it can be applied to energy spectrum images of at least two coordination modes based on the identification results.

[0103] In terms of substance identification, the energy spectrum image data obtained from at least two different combinations can reflect the characteristic information of radiation of different maximum energies passing through the inspected object. By using methods such as lookup tables, support vector machines (SVM), or logistic regression, the substances contained in the inspected object can be classified and identified, improving classification accuracy. Moreover, based on the identified classification information, the fused image or the energy spectrum image from at least two combinations can be colored, so that different substances in the image are clearly shown by different colors, improving readability and making it easier for users of multi-energy imaging systems to quickly understand the image and perform verification.

[0104] In some embodiments, the multiple radiations include at least one radiation having an energy spectrum with a maximum energy of less than or equal to 1 MeV and at least one radiation having an energy spectrum with a maximum energy of greater than 1 MeV.

[0105] X-ray radiation with a maximum energy of less than or equal to 1 MeV (such as keV-level radiation of 200 keV, 300 keV, 500 keV or 800 keV, or radiation of 1 MeV) can achieve low-energy scanning of the object being inspected. This low-energy scanning is relatively safe, has relatively low radiation hazards to the human body, and is suitable for scanning thin material areas.

[0106] In terms of spatial wire detection capability (WD), a typical value of 0.6 mm is found for keV-level imaging systems. Therefore, these systems can generate high-contrast scanned images with more detail in imaging thin material regions.

[0107] In terms of material identification, X-ray radiation with a maximum energy of 1 MeV or less can be used in conjunction with multi-energy spectral detectors to identify thin material regions. This allows for more precise material resolution based on the relative atomic number of the material, covering a wide range of materials with relatively low mass and thickness.

[0108] X-ray radiation with a maximum energy greater than 1 MeV (e.g., MeV-level radiation such as 3 MeV, 4 MeV, 6 MeV, and 9 MeV) can penetrate thick materials and materials with high atomic numbers, meeting the imaging requirements for these materials. Combining X-ray radiation with a maximum energy greater than 1 MeV with radiation with a maximum energy less than or equal to 1 MeV allows for imaging of materials with a wider range of mass thicknesses and atomic numbers, resulting in higher contrast and more detailed scanned images, and reducing the risk of missed detections of materials with different atomic numbers. Here, "thick materials" refers to materials with high mass thickness.

[0109] In terms of material identification, dual-energy X-ray radiation with a maximum energy greater than 1 MeV is more effective at identifying thick materials and materials with high atomic numbers. However, different thin materials are less susceptible to attenuation from this high-energy radiation, making them less suitable for identification.

[0110] X-ray radiation with a maximum energy of 1 MeV or less, combined with a multi-energy spectral detector, can effectively identify thin materials, while X-ray radiation with a maximum energy of greater than 1 MeV can effectively identify thick materials. Therefore, by combining the two, a wider range of material thicknesses can be identified, and the classification based on the atomic number of the material can be more refined and accurate.

[0111] In this way, by generating richer and more comprehensive energy spectrum image data, matching and optimization can be performed in image fusion and other aspects according to the physicochemical properties of the inspected object and the aspects of interest to the inspector (such as penetrability, details of thin materials, specific materials, etc.), thereby obtaining more targeted images. For example, it can simultaneously ensure that information on thick material regions and thin material regions is not lost, or it can improve the imaging contrast of materials with similar attenuation coefficients, not just limited to the four categories of organic matter, inorganic matter, mixtures, and heavy metals, or it can make the range of material mass, thickness, and atomic number values ​​applicable to material identification wider and more accurate. Intelligent identification of suspects based on the material identification structure helps improve the work efficiency of inspectors.

[0112] In this disclosure, the multi-spectral radiation source can be implemented in various ways. The multi-spectral radiation source can emit multiple X-ray pulses (e.g., from an accelerator or pulsed X-ray machine) or direct current X-rays (e.g., from an X-ray machine) with different maximum energies in a specific timing sequence. The X-ray pulses or direct current X-rays can be emitted by devices or combinations of devices.

[0113] 1. X-ray machine – This machine uses a high-voltage electric field to accelerate electrons, which then strike an anode target to generate X-rays, producing monoenergetic X-ray pulses or direct current X-rays. X-ray machines can be used in conjunction with accelerators.

[0114] 2. Electron Induction Accelerator – This type of accelerator uses an induced electric field generated by a time-varying magnetic field to accelerate electrons, which then strike an anode target to produce X-rays. Multi-energy pulses are obtained by controlling the electron extraction time. Electron induction accelerators can be used alone or in conjunction with X-ray machines, other electron induction accelerators, or linear accelerators.

[0115] 3. Linear Accelerator – A resonant accelerator that utilizes a high-frequency electric field to accelerate electrons, which then collide with an anode target to generate X-rays. Depending on the configuration and parameter settings of the microwave power source or electron gun, multi-energy pulses can be obtained using a single accelerating tube, or multiple accelerating tubes within a single accelerator can be used to obtain multi-energy pulses. Linear accelerators can be used independently or in conjunction with X-ray machines, electron induction accelerators, or other linear accelerators.

[0116] For multi-spectral radiation sources with different implementations, if the radiation source has different target locations, a registration operation for the energy spectrum image data can be added.

[0117] Figure 2 is a schematic diagram of the operation of a multi-spectral radiation source with multiple accelerating tubes in some embodiments of the multi-energy imaging system according to the present disclosure. Referring to Figure 2, in some embodiments, the multi-spectral radiation source 10 includes a linear accelerator having multiple accelerating tubes 111, 112, ..., 11n. The multiple accelerating tubes 111, 112, ..., 11n are configured to generate multiple types of radiation.

[0118] In scenarios where multiple accelerator tubes 111, 112, ..., 11n have different target locations, before image fusion of energy spectrum image data with at least two different configurations, the processor 30 can perform image registration on energy spectrum image data corresponding to at least two of the various radiation types based on the target locations of the multiple accelerator tubes 111, 112, ..., 11n, so as to perform image fusion on the registered energy spectrum image data. In Figure 2, the range of radiation emitted by each accelerator tube is illustrated using dashed lines, dotted lines, and double-dotted lines, respectively.

[0119] This multi-spectral radiation source uses multiple accelerating tubes with target points at different physical locations to generate various types of radiation. This allows the imaging system to generate scanning images from different angles, thereby obtaining richer spatial information and reducing the adverse effects of overlapping objects in the penetration direction of the radiation on the imaging. Moreover, the multiple accelerating tubes can be spatially arranged according to specific needs to adapt to different application scenarios and inspection objects, thus improving the application range of the imaging system.

[0120] In some embodiments, multiple accelerator tubes can be configured on the same accelerator, and the target points of each accelerator tube are positioned close to each other. The acquired images are processed using an image registration algorithm before fusion. The images corresponding to each target point can be registered according to the geometric projection relationship of feature points to eliminate ghosting.

[0121] Image registration algorithms are used to determine the spatial mapping relationship between pixels in one image and pixels in another. For scanned images corresponding to different target points, the aforementioned ORB (Oriented Fast and Rotated BRIEF) method or SIFT (Scale Invariant Feature Transform) method can also be used for keypoint detection, and the Brute Force algorithm can be used for feature matching. After matching multiple pairs of keypoints, the scanned images are geometrically transformed using the homographies matrix.

[0122] Figure 3 is a schematic diagram of the operation of a multi-spectral radiation source with a single accelerating tube and a control electron gun in some embodiments of the multi-energy imaging system according to the present disclosure. Referring to Figure 3, in some embodiments, the multi-spectral radiation source 10 includes a single accelerating tube 12 and a control electron gun 13, the control electron gun 13 being connected to the single accelerating tube 12 to cause the single accelerating tube 12 to generate various types of radiation. In Figure 3, the range of radiation emitted by the single accelerating tube is schematically indicated by a double-dotted line.

[0123] This multi-energy spectrum radiation source uses a controlled electron gun to achieve multi-energy beam output from a single accelerating tube. Moreover, the angle of the radiation emitted by the target point of the single accelerating tube can be relatively fixed, so the generated scanning images can be registered before fusion.

[0124] In other embodiments, the multi-spectral radiation source 10 may include a single accelerating tube and a control microwave power source. The control microwave power source may be connected to the single accelerating tube and cause the single accelerating tube to produce multiple types of radiation.

[0125] Figure 4A is a schematic diagram of the operation of a multi-spectral radiation source with two accelerators in some embodiments of the multi-energy imaging system according to the present disclosure. Referring to Figure 4A, in some embodiments, the multi-spectral radiation source 10 includes two accelerators 14 and 15. The two accelerators 14 and 15 are capable of producing a variety of radiation types.

[0126] Both accelerators 14 and 15 can be single-energy accelerators, both can be multi-energy accelerators, or they can be a single-energy accelerator and a multi-energy accelerator respectively. Both accelerators 14 and 15 can be linear accelerators, both can be electron induction accelerators, or they can be a linear accelerator and an electron induction accelerator respectively.

[0127] In scenarios where multiple accelerator tubes 111, 112, ..., 11n have different target locations, the processor 30 can perform image registration on energy spectrum image data corresponding to at least two of the various types of radiation based on the target locations of the two accelerators 14 and 15, so as to perform image fusion on the registered energy spectrum image data. In Figure 4A, the range of radiation emitted by the single-energy accelerator and the dual-energy accelerator is illustrated by dashed lines and dotted lines, respectively.

[0128] This multi-energy spectrum radiation source can generate various types of radiation with different maximum energies by combining multiple existing accelerators. It is more economical to implement and helps to reduce costs. Furthermore, the number and type of accelerators can be replaced or adjusted according to changes in actual needs to enhance adaptability.

[0129] Figure 4B is a schematic diagram of the operation of a multi-spectral radiation source having an accelerator and an X-ray machine in some embodiments of the multi-energy imaging system according to the present disclosure. Referring to Figure 4B, in some embodiments, the multi-spectral radiation source may further include an X-ray machine 17 and an accelerator 18, wherein the accelerator 18 may be a linear accelerator or an electron induction accelerator. In terms of quantity, the multi-spectral radiation source 10 may include one or more accelerators, or one or more X-ray machines.

[0130] Figure 5 is a schematic diagram of the structure of some other embodiments of the multi-energy imaging system according to the present disclosure. Referring to Figure 5, in some embodiments, the multi-energy imaging system further includes a filter 16. The filter 16 is located at the output of the multi-energy radiation source 10 and is configured to filter out at least a portion of the overlapping energy spectra of multiple radiation sources. In Figure 5, dashed lines with arrows indicate that the radiation emitted by the multi-energy radiation source 10 passes through the filter 16 and the object under inspection 4 and is received by the multi-energy detector 20.

[0131] For multiple types of radiation, there may be overlap between the continuous energy spectra. By setting a filter 16 at the output end of the multi-energy radiation source 10, at least the overlapping part of the energy spectra of multiple radiations is filtered out, so as to reduce the overlap of multiple continuous spectra, separate adjacent energy spectra as much as possible, and further widen the equivalent energy difference of the energy spectra of multiple radiations in the multi-energy mode, so that each radiation can be more clearly distinguished and the mutual influence between overlapping radiations is reduced.

[0132] In the selection of the multi-energy spectrum detector 20, the multi-energy spectrum detector 20 may include at least one of a detector with a multi-layer structure design and a detector that directly measures the intensity of the output signal. For example, the detector with a multi-layer structure design may include a dual-energy spectrum integrating detector.

[0133] Dual-energy spectral integrating detectors consist of a double-layer scintillation crystal and a photoelectric sensor (e.g., a photodiode, or PD). The double-layer scintillation crystal has different positions and thicknesses, allowing it to distinguish between high-energy and low-energy radiation, such as high-energy X-rays and low-energy X-rays. X-rays first pass through the thinner detector, resulting in a higher proportion of X-ray photons deposited in the low-energy spectral region, thus obtaining the low-energy component of the spectrum, which can be used for thin material identification. Simultaneously, a lower proportion of X-ray photons are deposited in the high-energy spectral region. These high-energy photons passing through the thin detector are received by the thicker detector, obtaining the high-energy component of the spectrum, which can be used for thick material identification. Considering the overlapping portions of the energy spectra of multi-energy radiation sources, filters can be added to minimize spectral overlap and improve energy separation capabilities.

[0134] For example, detectors that directly measure the intensity of the output signal may include SiPM spectral-resolved photon counting detectors or semiconductor detectors.

[0135] The SiPM (Silicon Photomultiplier) energy-resolution photon counting detector comprises a scintillation crystal and a silicon photomultiplier (SiPM) photoelectric sensor. This detector can be configured with different gating thresholds to divide the energy spectrum of radiation (e.g., the X-ray continuum) into multiple energy ranges, individually discriminating and counting each incident photon to obtain the various energy components within the spectrum.

[0136] Semiconductor detectors, such as high-purity germanium HPGe detectors and cadmium zinc telluride (CZT) compound semiconductor detectors, can directly generate electrical signals from incident radiation (such as X-rays) to measure the radiation, and then combine with multichannel energy spectrum analyzers to generate high-energy-resolution radiation spectrum data.

[0137] In various application scenarios of multi-energy imaging systems, based on the different maximum energy radiation provided by the multi-energy spectrum radiation source, the processor can pre-configure multiple scanning modes to match different types of objects under inspection, different inspection scenarios of the objects under inspection, and / or different inspection areas of the objects under inspection.

[0138] In some embodiments, the processor 30 is configured to switch between multiple scanning modes based on at least one of the type of object being inspected, the inspection scenario, and the scanning area, wherein each scanning mode differs from the other scanning modes at least in the combination of pulses emitted by the multi-spectral radiation source 10 in each cycle.

[0139] The types of objects to be inspected can include goods, vehicles, etc. Vehicles can be further subdivided into automobiles, trains, aircraft, ships, etc. Based on their carrying content or control method, automobiles can be further subdivided into buses, trucks, etc., or driverless vehicles, manned vehicles, etc. The inspection scenarios for the objects to be inspected can include airports, ports, train station entrances, etc. The inspection areas for the objects to be inspected can include different areas defined in at least one direction, or sides in different directions, or areas that perform different functions or have different inspection requirements, such as the driver's cab area and cargo box area of ​​a truck.

[0140] The pulse combination emitted by the multi-spectral radiation source 10 in each cycle under each scanning mode differs from that under other scanning modes. The types of radiation contained in the different pulse combinations are at least partially different. For example, if the pulse combination emitted by the multi-spectral radiation source 10 in each cycle under the first scanning mode includes radiation a and radiation b, denoted here as [a,b], then the pulse combinations [a], [b], [a,c], [b,c], or [c] emitted by the multi-spectral radiation source 10 in each cycle under the second scanning mode are all different from the pulse combination [a,b] corresponding to the first scanning mode.

[0141] For ease of understanding, a multi-spectral radiation source 10 capable of emitting three types of radiation is used as an example. In this embodiment, the multiple radiations include a first radiation i1 with a first maximum energy spectrum, a second radiation i2 with a second maximum energy spectrum, and a third radiation i3 with a third maximum energy spectrum. The first maximum energy is less than or equal to 1 MeV, and both the second and third maximum energies are greater than 1 MeV, with the third maximum energy being greater than the second maximum energy. For example, the first maximum energy is 0.5 MeV, the second maximum energy is 4 MeV, and the third maximum energy is 7 MeV. Another example is the first maximum energy being 0.3 MeV, the second maximum energy being 3 MeV, and the third maximum energy being 6 MeV. Yet another example is the first maximum energy being 0.6 MeV, the second maximum energy being 6 MeV, and the third maximum energy being 9 MeV.

[0142] Figures 6A and 6B are schematic diagrams illustrating two examples of first pulse combinations emitted by a multi-spectral radiation source in a first scanning mode, according to some embodiments of the multi-energy imaging system of the present disclosure. Figures 7A and 7B are schematic diagrams illustrating two examples of second pulse combinations emitted by a multi-spectral radiation source in a second scanning mode, according to some embodiments of the multi-energy imaging system of the present disclosure. Figures 8A and 8B are schematic diagrams illustrating two examples of third pulse combinations emitted by a multi-spectral radiation source in a third scanning mode, according to some embodiments of the multi-energy imaging system of the present disclosure. Figures 9A, 9B, 9C, 9D, 9E, and 9F are schematic diagrams illustrating four examples of fourth pulse combinations emitted by a multi-spectral radiation source in a fourth scanning mode, according to some embodiments of the multi-energy imaging system of the present disclosure.

[0143] Referring to Figures 6A to 9D, in some embodiments, the multiple scanning modes include at least two of a first scanning mode, a second scanning mode, a third scanning mode, and a fourth scanning mode; the processor 30 is configured to:

[0144] In the first scanning mode, the multi-energy spectrum radiation source 10 emits a first pulse combination in each cycle, the first pulse combination including only at least one pulse of the first ray radiation i1;

[0145] In the second scanning mode, the multi-energy spectrum radiation source 10 emits a second pulse combination in each cycle, the second pulse combination including at least one pulse of second radiation i2 and at least one pulse of third radiation i3;

[0146] In the third scanning mode, the multi-energy spectrum radiation source 10 emits a third pulse combination in each cycle, the third pulse combination including at least one pulse of the second radiation i2 and at least one pulse of the first radiation i1.

[0147] In the fourth scanning mode, the multi-energy spectrum radiation source 10 emits a fourth pulse combination in each cycle, the fourth pulse combination including at least one pulse of the first radiation i1, at least one pulse of the second radiation i2, and at least one pulse of the third radiation i3.

[0148] In Figures 6A to 9D, the horizontal axis represents the pulse timing of the multi-energy spectrum radiation source 10, and t on the horizontal axis represents one period. The pulse combinations repeat periodically, and the vertical axis represents the maximum energy of the corresponding X-ray pulse. In each figure, black arrows indicate the different types of X-ray radiation corresponding to the pulses in each period, namely i1, i2, and i3.

[0149] Figures 6A and 6B illustrate two combinations of first pulses emitted by a multi-energy spectrum radiation source in the first scanning mode. The first pulse combination in Figure 6A includes only two pulses of the first radiation i1, while the first pulse combination in Figure 6B includes only a single pulse of the first radiation i1. This combination of first pulses in the first scanning mode offers strong material resolution for thin materials, making it suitable for imaging and identification of thin materials. It also reduces the radiation dose to the inspected object, improving safety. The first pulse combinations shown in Figures 6A and 6B can be used for detection in areas where radiation dose reception is limited but imaging and material identification are required, such as material identification in a driver's cab or scanning a bus.

[0150] Figures 7A and 7B illustrate two combinations of second pulses emitted by a multi-energy spectrum radiation source in the second scanning mode. The second pulse combination in Figure 7A includes a single pulse of second radiation i2 and a single pulse of third radiation i3, while the second pulse combination in Figure 7B includes two pulses of second radiation i2 and two pulses of third radiation i3. This combination of second pulses in the second scanning mode has strong penetrating power and can be applied to imaging and material identification of thick materials.

[0151] Figures 8A and 8B illustrate two combinations of third pulses emitted by a multi-energy spectrum radiation source in the third scanning mode. The third pulse combination in Figure 8A includes a single pulse of the second radiation i2 and a single pulse of the first radiation i1, while the third pulse combination in Figure 8B includes two pulses of the second radiation i2 and two pulses of the first radiation i1. This combination of third pulses in the third scanning mode can be applied to the detection of areas where radiation dose reception is limited and imaging and material identification are required, such as for material identification in a driver's cab area.

[0152] Figures 9A to 9F illustrate four combinations of fourth pulses emitted by the multi-energy spectrum radiation source in the fourth scanning mode. The fourth pulse combinations in Figures 9A and 9B include a single pulse of the first radiation i1, a single pulse of the second radiation i2, and a single pulse of the third radiation i3. The fourth pulse combination in Figure 9C includes a single pulse of the second radiation i2, a single pulse of the third radiation i3, and two pulses of the first radiation i1. The fourth pulse combination in Figure 9D includes a single pulse of the second radiation i2, a single pulse of the third radiation i3, and four pulses of the first radiation i1.

[0153] The fourth pulse combination in Figure 9E includes a single pulse of the second radiation i2, a single pulse of the third radiation i3, and six pulses of the first radiation i1. The fourth pulse combination in Figure 9F includes two pulses of the second radiation i2, two pulses of the third radiation i3, and four pulses of the first radiation i1. This fourth pulse combination in the fourth scanning mode can be applied to the scanning of cargo sections, achieving strong penetration and meeting the imaging and material identification requirements of thick materials and materials with high atomic numbers. Using one or more pulses of the first radiation i1 can increase the total output and sampling rate of radiation with a maximum energy spectrum of less than or equal to 1 MeV, thereby improving the image quality and spatial resolution of thin material regions.

[0154] Referring to Figures 9C to 9F, the fourth pulse combination begins with a pulse of the third ray radiation i3 at the start of the period. The number of pulses of the first ray radiation i1 can be a multiple of 2, such as the two pulses in Figure 9C, the four pulses in Figures 9D and 9F, and the six pulses in Figure 9E. For a fourth pulse combination containing a single pulse or two pulses of the first ray radiation i1, the pulse of the first ray radiation i1 can exit at positions such as T / 4, T / 3, 2T / 3, or 3T / 4. For a fourth pulse combination containing four pulses of the first ray radiation i1, the pulse of the first ray radiation i1 can exit at positions such as T / 6, T / 3, 2T / 3, 5T / 6, T / 8, 3T / 8, 5T / 8, or 7T / 8. For a fourth pulse combination containing six pulses of the first ray radiation i1, the pulse of the first ray radiation i1 can exit at positions such as T / 8, T / 4, 3T / 8, 5T / 8, 3T / 4, or 7T / 8.

[0155] For the scanning mode, in addition to distinguishing by the combination of pulses emitted by the multi-energy spectrum radiation source 10 in each cycle, it can also be further distinguished by the energy components in the energy spectrum that can be sensed by the multi-energy spectrum detector 20.

[0156] In some embodiments, the multiple energy components include a first energy component and a second energy component, wherein the average energy of the first energy component is less than the average energy of the second energy component; the processor 30 is configured to:

[0157] Obtain energy spectrum image data of at least two coordination modes between various pulse combinations passing through the object under test and at least one of a first energy component and a second energy component, and identify substances based on the energy spectrum image data of at least two coordination modes;

[0158] In the first scanning mode, the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the first X-ray radiation i1.

[0159] In the second scanning mode, the multi-energy spectrum detector 20 obtains the second energy component in the energy spectrum of the second radiation i2 and the third radiation i3, or the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the second radiation i2 and the third radiation i3.

[0160] In the third scanning mode, the multi-energy spectrum detector 20 obtains the second energy component in the energy spectrum of the first radiation i1 and the second radiation i2, or the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the first radiation i1 and the second radiation i2.

[0161] In the fourth scanning mode, the multi-energy spectrum detector 20 obtains the second energy component in the energy spectrum of the first radiation i1, the second radiation i2, and the third radiation i3, or the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the first radiation i1, the second radiation i2, and the third radiation i3.

[0162] For the first scanning mode, since the first pulse combination emitted by the multi-energy spectrum radiation source 10 only includes the pulse of the first ray radiation i1, in order to achieve material identification, the multi-energy spectrum detector 20 detects both the first energy component and the second energy component in the energy spectrum of the first ray radiation i1. In this way, by comparing and analyzing the absorption data of the high-energy component and the low-energy component in the continuous spectrum of the first ray radiation i1 by the multi-energy spectrum detector 20, the equivalent atomic number and other parameters of the material can be further determined.

[0163] For the second, third, and fourth scanning modes, since the combination of the second, third, and fourth pulses emitted by the multi-energy spectrum radiation source 10 includes pulses of two or three types of radiation, the high-energy component detection using the multi-energy spectrum detector 20 can achieve material identification, which is beneficial for reducing energy consumption. These three modes can also use the multi-energy spectrum detector 20 to detect both high-energy and low-energy components to generate more energy spectrum image data, which helps improve the resolution and accuracy of material identification.

[0164] Figures 10A, 10B, 10C, 10D, and 10E are schematic diagrams illustrating vehicle-area scanning and detector acquisition in a truck inspection scenario according to some embodiments of the multi-energy imaging system of this disclosure. Referring to Figures 10A to 10E, the scanning mode for vehicle-area inspection is explained using a scenario where a driver is conducting a rapid inspection of a truck driven by a multi-energy imaging system including a multi-energy accelerator (6 / 3 / 0.3MeV) and a dual-energy detector (1mm~8mm / 20mm~60mm dual-layer CsI scintillation crystal + PD photoelectric sensor) as an example.

[0165] In this scenario, the object under inspection includes a truck with a cab area 41 and a cargo box area 42. Accordingly, the processor 30 is configured to: enable the multi-spectral radiation source 10 to scan the cab area 41 through a first scanning mode or a third scanning mode, or enable the multi-spectral radiation source 10 not to scan the cab area 41; enable the multi-spectral radiation source 10 to scan the cargo box area 42 through a second scanning mode or a fourth scanning mode.

[0166] A multi-energy accelerator may include a pulse modulator, an X-ray machine, and a constant-temperature water-cooling system. Through a microwave power and transmission system, a 6 / 3 MeV accelerating tube, and a 0.3 MeV accelerating tube arranged within the X-ray machine, it can output 6 / 3 / 0.3 MeV X-ray pulses according to a predetermined pulse quantity ratio and a predetermined timing sequence. Here, the 6 / 3 / 0.3 MeV X-ray pulses correspond to i3, i2, and i1 in Figures 10A to 10E.

[0167] The dual-energy detector has two layers of scintillation crystals along the X-ray incident direction. The X-ray photons first pass through the 4 mm thick low-energy scintillation crystal CsI, generating a low-energy component image signal, and then pass through the 30 mm thick high-energy scintillation crystal CsI, generating a high-energy component image signal. Here, the low-energy scintillation crystal CsI and the high-energy scintillation crystal CsI correspond to s1 and s2 in Figures 10A to 10E, respectively.

[0168] Referring to Figure 10A, when the driver drives the truck into the scanning channel, the vehicle type recognition system (e.g., multi-light curtain photoelectric, multi-group vertical light curtain high-brightness curtain, laser sensor, visible light, and other vehicle type recognition technologies) identifies the vehicle type and provides information such as real-time vehicle speed, vehicle outline, and cab length, thereby determining the truck's cab area 41 and cargo box area 42. Based on the above recognition information, the multi-energy imaging system performs regional scanning of the inspected truck. It scans the cab area using a single beam of 0.3 MeV first radiation i1, and then quickly switches to three radiation types i3, i2, and i1 (i.e., 6 / 3 / 0.3 MeV) to achieve multi-energy alternating scanning of the cargo box area 42. This is equivalent to having the multi-energy spectrum radiation source 10 scan the cab area 41 using the first scanning mode and then scan the cargo box area 42 using the fourth scanning mode.

[0169] Because the target points of the two accelerating tubes in the multi-energy accelerator are spatially misaligned, separated by a predetermined distance (e.g., 25mm, 30mm, or 37mm), the energy spectrum image data corresponding to the two target points need to be registered according to the geometric projection relationship of the feature points to eliminate ghosting. Based on the information representing penetration capability (e.g., grayscale values) contained in each original energy spectrum image data, the effective information is fused into a single image (e.g., a grayscale image) according to image weights. The fused image can simultaneously demonstrate good spatial filament resolution and penetration performance, achieving overall image quality and performance improvement without switching between high and low energies. This allows for effective penetration of thick material regions while minimizing the loss of information from thin material regions.

[0170] For the cab area 41, material identification is achieved using a pulse-matched dual-energy detector emitting 0.3 MeV radiation. For the cargo compartment area 42, material identification of thin material areas is achieved using a pulse-matched dual-energy detector emitting 0.3 MeV radiation from the first ray, while material identification of thick material areas is achieved using a pulse-matched high-energy detector emitting the third ray and the second ray (i.e., 6 / 3 MeV). Material identification images are obtained through image fusion, which is then used to colorize the image obtained after image registration and fusion.

[0171] Referring to Figure 10B, unlike Figure 10A, an avoidance mode is adopted for the cab area 41. That is, the multi-spectral radiation source 10 does not scan the cab area 41, which greatly improves the driver's safety during the scanning process. When the cargo compartment area 42 is scanned, the material identification of thin material areas can be achieved through a pulse-matched dual-energy detector using the first 0.3 MeV radiation, and the material identification of thick material areas can be achieved through a pulse-matched high-energy detector using the third and second 6 / 3 MeV radiation. This is equivalent to the multi-spectral radiation source 10 scanning the cargo compartment area 42 through a fourth scanning mode.

[0172] Referring to Figure 10C, the main differences from Figure 10A are in three aspects. First, both the cab area 41 and the cargo area 42 only use the high-energy component detection function of the dual-energy detector, which can reduce costs. Second, for the cab area 41, the high-energy scintillation crystal CsI of the dual-energy detector is matched with pulses of 0.3MeV and 3MeV ray radiation. This is equivalent to the multi-energy spectrum radiation source 10 scanning the cab area 41 through a third scanning mode, combined with the detection of high-energy components by the multi-energy spectrum detector. In this way, while scanning with a pulse combination containing 0.3MeV ray radiation to meet driver safety requirements, the dual-energy scanning of the cab area 41 enables material identification within the cab.

[0173] The third aspect is that for the cargo compartment area 42, imaging of thin and thick material areas can be achieved by matching the pulse of the first ray radiation (0.3 MeV) with the pulse of the third ray radiation and the pulse of the second ray radiation (i.e., 6 / 3 MeV) with a high-energy detector, and energy consumption can be effectively saved.

[0174] Referring to Figure 10D, unlike Figure 10A, only the high-energy component detection function of a dual-energy detector is used for both the cab area 41 and the cargo compartment area 42. In this case, cab imaging can be achieved without the need for material identification in the cab, ensuring driver safety. For the cargo compartment area 42, material identification of thin and thick material areas can be achieved by matching the pulses of the first radiation (0.3 MeV) and the pulses of the third and second radiations (i.e., 6 / 3 MeV) with a high-energy detector, effectively saving energy consumption.

[0175] Referring to Figure 10E, the difference from Figure 10A is that for cargo compartment area 42, material identification of the thick material region is achieved through a pulse-matched dual-energy detector using third-ray radiation and second-ray radiation (i.e., 6 / 3 MeV). Material identification images are obtained through image fusion, which is then used to colorize the image obtained after the previous image registration and fusion.

[0176] Figures 11A and 11B are schematic diagrams of scanning and detector acquisition of a bus in a bus inspection scenario according to some embodiments of the multi-energy imaging system of this disclosure.

[0177] Referring to Figures 11A and 11B, the scanning mode for vehicle inspection is explained using a scenario where a multi-energy imaging system, which includes a multi-energy accelerator (6 / 3 / 0.3MeV) and a dual-energy detector (1mm~8mm / 20mm~60mm dual-layer CsI scintillation crystal + PD photoelectric sensor), performs a rapid inspection of a passing bus.

[0178] In this scenario, the object under inspection includes the bus 40. Accordingly, the processor 30 is configured to either enable the multi-spectral radiation source 10 to perform a full vehicle scan of the bus 40 using a first scanning mode or a third scanning mode, or to disable the multi-spectral radiation source 10 from scanning the entire bus 40.

[0179] The relevant configurations of the multi-energy accelerator and dual-energy detector can be found in the previous descriptions of Figures 10A to 10D, and will not be repeated here.

[0180] Referring to Figure 11A, when the driver drives the bus 40 into the scanning channel, the vehicle type recognition system (e.g., multi-light curtain photoelectric, multi-group vertically arranged high-brightness curtain, laser sensor, visible light, and other vehicle type recognition technologies) identifies the vehicle type and provides information such as real-time vehicle speed and vehicle outline, thereby determining that the vehicle is a bus. Based on the above recognition information, the multi-energy imaging system emits a single beam of 0.3 MeV first-ray radiation i1 to perform a whole-vehicle scan of the inspected bus 40. This is equivalent to having the multi-energy spectrum radiation source 10 perform a whole-vehicle scan of the bus 40 through the first scanning mode.

[0181] Referring to Figure 11B, the difference from Figure 11A is that the bus 40 is scanned by a high-energy scintillation crystal CsI of a dual-energy detector using pulsed matching of 0.3 MeV and 3 MeV radiation. This is equivalent to the multi-energy spectrum radiation source 10 performing a full-vehicle scan of the bus 40 through a third scanning mode, combined with the detection of high-energy components by the multi-energy spectrum detector. Thus, while ensuring the safety of the driver and other occupants through pulse combinations containing 0.3 MeV radiation, the dual-energy scanning also enables material identification within the bus.

[0182] Referring to Figures 10A to 11B above, the dual-energy detector in the multi-energy imaging system can be replaced with a SiPM spectral-resolution photon counting detector to detect more energy components in the X-ray radiation spectrum, thereby achieving better material identification and image quality. Accordingly, the processor can control the pulse of the X-ray radiation output from the multi-energy accelerator and the energy components selected for detection by the SiPM spectral-resolution photon counting detector based on the operational scenario of truck or bus inspection.

[0183] Based on the multi-energy imaging systems of the above embodiments, in one aspect of this disclosure, a multi-energy imaging method according to any of the foregoing embodiments of the multi-energy imaging system is also provided. The multi-energy imaging method includes:

[0184] Obtain energy spectrum image data of at least two coordination modes between multiple types of radiation and multiple energy components passing through the object under inspection.

[0185] When scanning and imaging the object under inspection using the multi-energy spectrum radiation source 10, multiple radiation sources can be combined with the multi-energy spectrum detector 20 to detect multiple energy components. This allows for various combinations, such as two or more radiation sources combined with the detection of one energy component, or one radiation source combined with the detection of two or more energy components, or even more combinations of two or more radiation sources combined with the detection of two or more energy components. This allows for obtaining energy spectrum image data from at least two different combinations in a single scan. The energy spectrum image data from various combinations can reflect richer feature information about the object under inspection, which is beneficial for subsequent operations such as image processing, material identification, and analysis, effectively improving the adaptability of imaging the object under inspection.

[0186] In some embodiments, the multi-energy imaging method further includes: image fusion of energy spectrum image data with at least two coordination modes.

[0187] By fusing energy spectrum image data from at least two different combinations, the fused image can reflect richer feature information of the object under examination, improve imaging performance, and thus effectively enhance the adaptability of the imaging system to the object under examination.

[0188] In some embodiments, the multi-energy imaging method further includes: identifying substances based on energy spectrum image data of at least two coordination modes, and coloring the images based on the identification results. Here, coloring can be applied to a fused image obtained after image fusion based on the identification results, or it can be applied to energy spectrum images of at least two coordination modes based on the identification results.

[0189] In some embodiments, the plurality of radiations includes at least one type of radiation having an energy spectrum with a maximum energy of less than or equal to 1 MeV and at least one type of radiation having an energy spectrum with a maximum energy of greater than 1 MeV.

[0190] In some embodiments, the multi-energy imaging method further includes switching between multiple scanning modes based on at least one of the type of object under examination, the examination scenario, and the scanning area, wherein each scanning mode differs from the other scanning modes at least in the combination of pulses emitted by the multi-energy spectral radiation source 10 in each cycle.

[0191] In some embodiments, the multiple radiations include a first radiation i1 with a first maximum energy spectrum, a second radiation i2 with a second maximum energy spectrum, and a third radiation i3 with a third maximum energy spectrum, wherein the first maximum energy is less than or equal to 1 MeV, the second maximum energy and the third maximum energy are both greater than 1 MeV, and the third maximum energy is greater than the second maximum energy; the multiple scanning modes include at least two of a first scanning mode, a second scanning mode, a third scanning mode, and a fourth scanning mode.

[0192] Correspondingly, multi-energy imaging methods also include:

[0193] In the first scanning mode, the multi-energy spectrum radiation source 10 emits a first pulse combination in each cycle, the first pulse combination including only at least one pulse of the first ray radiation i1;

[0194] In the second scanning mode, the multi-energy spectrum radiation source 10 emits a second pulse combination in each cycle, the second pulse combination including at least one pulse of second radiation i2 and at least one pulse of third radiation i3;

[0195] In the third scanning mode, the multi-energy spectrum radiation source 10 emits a third pulse combination in each cycle, the third pulse combination including at least one pulse of the second radiation i2 and at least one pulse of the first radiation i1.

[0196] In the fourth scanning mode, the multi-energy spectrum radiation source 10 emits a fourth pulse combination in each cycle, the fourth pulse combination including at least one pulse of the first radiation i1, at least one pulse of the second radiation i2, and at least one pulse of the third radiation i3.

[0197] In some embodiments, the multiple energy components include a first energy component and a second energy component, wherein the average energy of the first energy component is less than the average energy of the second energy component; the step of obtaining energy spectrum image data of at least two combinations between multiple radiations passing through the object under inspection and multiple energy components includes: obtaining energy spectrum image data of at least two combinations between at least one of the first radiation i1, the second radiation i2 and the third radiation i3 passing through the object under inspection and at least one of the first energy component and the second energy component.

[0198] Correspondingly, multi-energy imaging methods also include:

[0199] Substance identification based on energy spectrum image data of at least two coordination modes;

[0200] In the first scanning mode, the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the first X-ray radiation i1.

[0201] In the second scanning mode, the multi-energy spectrum detector 20 obtains the second energy component in the energy spectrum of the second radiation i2 and the third radiation i3, or the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the second radiation i2 and the third radiation i3.

[0202] In the third scanning mode, the multi-energy spectrum detector 20 obtains the second energy component in the energy spectrum of the first radiation i1 and the second radiation i2, or the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the first radiation i1 and the second radiation i2.

[0203] In the fourth scanning mode, the multi-energy spectrum detector 20 obtains the second energy component in the energy spectrum of the first radiation i1, the second radiation i2, and the third radiation i3, or the multi-energy spectrum detector 20 obtains the first energy component and the second energy component in the energy spectrum of the first radiation i1, the second radiation i2, and the third radiation i3.

[0204] In some embodiments, the object under inspection includes a truck having a cab area 41 and a cargo box area 42. Accordingly, the multi-energy imaging method further includes: causing the multi-energy radiation source 10 to scan the cab area 41 using a first scanning mode or a third scanning mode, or causing the multi-energy radiation source 10 not to scan the cab area 41; and causing the multi-energy radiation source 10 to scan the cargo box area 42 using a second scanning mode or a fourth scanning mode.

[0205] In some embodiments, the object under inspection includes a bus 40; wherein, the multi-energy imaging method further includes: enabling the multi-energy radiation source 10 to perform a whole-vehicle scan of the bus 40 through a first scanning mode or a third scanning mode, or enabling the multi-energy radiation source 10 not to scan the whole-vehicle of the bus 40.

[0206] This specification describes multiple embodiments in a progressive manner, with each embodiment having a different focus. Similar or identical parts between embodiments can be referred to interchangeably. For method embodiments, since their overall structure and involved steps correspond to the content in system embodiments, the description is relatively simple; relevant parts can be referred to in the descriptions of the system embodiments.

[0207] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0208] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.

Claims

1. A multi-energy imaging system, comprising: A multi-spectral radiation source (10) is configured to produce at least one of a variety of ray radiations, the variety of ray radiations having energy spectra with different maximum energies; The multi-energy spectrum detector (20) is capable of obtaining at least one of the multiple energy components in the energy spectrum of X-ray radiation; and The processor (30), signal-connected to the multi-spectral radiation source (10) and the multi-spectral detector (20), is configured to acquire spectral image data of at least two combinations of the various radiations passing through the object under inspection and the various energy components.

2. The multi-energy imaging system according to claim 1, wherein, The processor (30) is configured to perform image fusion on the energy spectrum image data of the at least two coordination modes.

3. The multi-energy imaging system according to claim 1 or 2, wherein, The processor (30) is configured to identify substances based on energy spectrum image data of the at least two coordination modes and to color them according to the identification results.

4. The multi-energy imaging system according to any one of claims 1-3, wherein, The plurality of radiations includes at least one type of radiation with an energy spectrum having a maximum energy of less than or equal to 1 MeV and at least one type of radiation with an energy spectrum having a maximum energy of greater than 1 MeV.

5. The multi-energy imaging system according to any one of claims 1-4, wherein, The multi-spectral radiation source (10) includes one or more combinations of linear accelerators, electron induction accelerators, and X-ray machines.

6. The multi-energy imaging system according to any one of claims 1-5, further comprising: A filter (16), located at the output end of the multi-spectral radiation source (10), is configured to filter out at least a portion of the overlapping energy spectra of the multi-spectral radiation.

7. The multi-energy imaging system according to any one of claims 1-6, wherein, The multi-spectral detector (20) includes at least one of a detector with a multi-layer structure design and a detector that directly measures the intensity of the output signal.

8. The multi-energy imaging system according to any one of claims 1-7, wherein, The processor (30) is configured to switch between multiple scanning modes based on at least one of the type of the object being inspected, the inspection scenario, and the scanning area, wherein each of the multiple scanning modes is different from the other scanning modes in at least the combination of pulses emitted by the multi-spectral radiation source (10) in each cycle.

9. The multi-energy imaging system according to claim 8, wherein, The multiple types of radiation include a first radiation (i1) with a first maximum energy spectrum, a second radiation (i2) with a second maximum energy spectrum, and a third radiation (i3) with a third maximum energy spectrum. The first maximum energy is less than or equal to 1 MeV, the second maximum energy and the third maximum energy are both greater than 1 MeV, and the third maximum energy is greater than the second maximum energy.

10. The multi-energy imaging system according to claim 9, wherein, The multiple scanning modes include at least two of the following: a first scanning mode, a second scanning mode, a third scanning mode, and a fourth scanning mode; The processor (30) is configured to: In the first scanning mode, the multi-spectral radiation source (10) emits a first pulse combination in each cycle, the first pulse combination including only at least one pulse of the first ray radiation (i1); In the second scanning mode, the multi-spectral radiation source (10) emits a second pulse combination in each cycle, the second pulse combination including at least one pulse of the second ray radiation (i2) and at least one pulse of the third ray radiation (i3); In the third scanning mode, the multi-energy spectrum radiation source (10) emits a third pulse combination in each cycle, the third pulse combination including at least one pulse of the second radiation (i2) and at least one pulse of the first radiation (i1); In the fourth scanning mode, the multi-energy spectrum radiation source (10) emits a fourth pulse combination in each cycle, the fourth pulse combination including at least one pulse of the first radiation (i1), at least one pulse of the second radiation (i2) and at least one pulse of the third radiation (i3).

11. The multi-energy imaging system according to claim 10, wherein, The multiple energy components include a first energy component and a second energy component, wherein the average energy of the first energy component is less than the average energy of the second energy component; The processor (30) is configured to: Obtain energy spectrum image data of at least two coordination modes between various pulse combinations passing through the object under test and at least one of the first energy component and the second energy component, and perform substance identification based on the energy spectrum image data of the at least two coordination modes; In the first scanning mode, the multi-energy spectrum detector (20) obtains the first energy component and the second energy component in the energy spectrum of the first ray radiation (i1); In the second scanning mode, the multi-spectral detector (20) is made to obtain the second energy component in the energy spectrum of the second radiation (i2) and the third radiation (i3), or the multi-spectral detector (20) is made to obtain the first energy component and the second energy component in the energy spectrum of the second radiation (i2) and the third radiation (i3); In the third scanning mode, the multi-spectral detector (20) is made to obtain the second energy component in the energy spectrum of the first radiation (i1) and the second radiation (i2), or the multi-spectral detector (20) is made to obtain the first energy component and the second energy component in the energy spectrum of the first radiation (i1) and the second radiation (i2). In the fourth scanning mode, the multi-energy spectrum detector (20) is made to obtain the second energy component in the energy spectrum of the first radiation (i1), the second radiation (i2) and the third radiation (i3), or the multi-energy spectrum detector (20) is made to obtain the first energy component and the second energy component in the energy spectrum of the first radiation (i1), the second radiation (i2) and the third radiation (i3).

12. The multi-energy imaging system according to claim 10 or 11, wherein, The inspected object includes a truck having a cab area (41) and a cargo box area (42), and the processor (30) is configured to: The multi-spectral radiation source (10) can scan the cab area (41) using the first scanning mode or the third scanning mode, or the multi-spectral radiation source (10) can choose not to scan the cab area (41). The multi-spectral radiation source (10) is used to scan the cargo compartment area (42) using the second or fourth scanning mode.

13. The multi-energy imaging system according to claim 10 or 11, wherein, The object under inspection includes a passenger vehicle (40), and the processor (30) is configured to: The multi-spectral radiation source (10) can perform a full vehicle scan of the bus (40) using either the first or third scanning mode, or the multi-spectral radiation source (10) can choose not to scan the entire bus (40).

14. A multi-energy imaging method for a multi-energy imaging system according to any one of claims 1-13, comprising: Obtain energy spectrum image data of at least two coordination modes between the various types of radiation and the various energy components passing through the object under inspection.

15. The multi-energy imaging method according to claim 14, further comprising: Image fusion is performed on the energy spectrum image data of the at least two coordination methods.

16. The multi-energy imaging method according to claim 14 or 15, further comprising: Material identification is performed based on the energy spectrum image data of the at least two coordination methods, and coloring is performed based on the identification results.

17. The multi-energy imaging method according to any one of claims 14-16, wherein, The plurality of radiations includes at least one type of radiation with an energy spectrum having a maximum energy of less than or equal to 1 MeV and at least one type of radiation with an energy spectrum having a maximum energy of greater than 1 MeV.

18. The multi-energy imaging method according to any one of claims 14-17, further comprising: The system switches between multiple scanning modes depending on at least one of the type of object being inspected, the inspection scenario, and the scanning area. Each of the multiple scanning modes is different from the other scanning modes in at least the combination of pulses emitted by the multi-spectral radiation source (10) in each cycle.

19. The multi-energy imaging method according to claim 18, wherein, The multiple radiation sources include a first radiation source (i1) with a first maximum energy spectrum, a second radiation source (i2) with a second maximum energy spectrum, and a third radiation source (i3) with a third maximum energy spectrum, wherein the first maximum energy is less than or equal to 1 MeV, the second maximum energy and the third maximum energy are both greater than 1 MeV, and the third maximum energy is greater than the second maximum energy; the multiple scanning modes include at least two of a first scanning mode, a second scanning mode, a third scanning mode, and a fourth scanning mode; The multi-energy imaging method further includes: In the first scanning mode, the multi-spectral radiation source (10) emits a first pulse combination in each cycle, the first pulse combination including only at least one pulse of the first ray radiation (i1); In the second scanning mode, the multi-spectral radiation source (10) emits a second pulse combination in each cycle, the second pulse combination including at least one pulse of the second ray radiation (i2) and at least one pulse of the third ray radiation (i3); In the third scanning mode, the multi-energy spectrum radiation source (10) emits a third pulse combination in each cycle, the third pulse combination including at least one pulse of the second radiation (i2) and at least one pulse of the first radiation (i1); In the fourth scanning mode, the multi-energy spectrum radiation source (10) emits a fourth pulse combination in each cycle, the fourth pulse combination including at least one pulse of the first radiation (i1), at least one pulse of the second radiation (i2) and at least one pulse of the third radiation (i3).

20. The multi-energy imaging method according to claim 19, wherein, The multiple energy components include a first energy component and a second energy component, wherein the average energy of the first energy component is less than the average energy of the second energy component; The step of obtaining energy spectrum image data of at least two coordination modes between the various types of radiation and the various energy components passing through the object under examination includes: Obtain energy spectrum image data of at least two coordination modes between at least one of the first radiation (i1), the second radiation (i2), and the third radiation (i3) passing through the object under inspection and at least one of the first energy component and the second energy component; The multi-energy imaging method further includes: Substance identification is performed based on energy spectrum image data of at least two of the aforementioned coordination methods; In the first scanning mode, the multi-energy spectrum detector (20) obtains the first energy component and the second energy component in the energy spectrum of the first ray radiation (i1); In the second scanning mode, the multi-spectral detector (20) is made to obtain the second energy component in the energy spectrum of the second radiation (i2) and the third radiation (i3), or the multi-spectral detector (20) is made to obtain the first energy component and the second energy component in the energy spectrum of the second radiation (i2) and the third radiation (i3); In the third scanning mode, the multi-spectral detector (20) is made to obtain the second energy component in the energy spectrum of the first radiation (i1) and the second radiation (i2), or the multi-spectral detector (20) is made to obtain the first energy component and the second energy component in the energy spectrum of the first radiation (i1) and the second radiation (i2). In the fourth scanning mode, the multi-energy spectrum detector (20) is made to obtain the second energy component in the energy spectrum of the first radiation (i1), the second radiation (i2) and the third radiation (i3), or the multi-energy spectrum detector (20) is made to obtain the first energy component and the second energy component in the energy spectrum of the first radiation (i1), the second radiation (i2) and the third radiation (i3).

21. The multi-energy imaging method according to claim 19 or 20, wherein, The objects to be inspected include trucks with a cab area (41) and a cargo box area (42); The multi-energy imaging method further includes: The multi-spectral radiation source (10) can scan the cab area (41) using the first scanning mode or the third scanning mode, or the multi-spectral radiation source (10) can choose not to scan the cab area (41). The multi-spectral radiation source (10) is used to scan the cargo compartment area (42) using the second or fourth scanning mode.

22. The multi-energy imaging method according to claim 19 or 20, wherein, The object under inspection includes a passenger vehicle (40); wherein, the multi-energy imaging method further includes: The multi-spectral radiation source (10) can perform a full vehicle scan of the bus (40) using either the first or third scanning mode, or the multi-spectral radiation source (10) can choose not to scan the entire bus (40).

Images