Radiation inspection system

Abstract

The present disclosure provides a radiation inspection system, having an inspection channel through which an object to be inspected passes, and comprising a transmission inspection device, a backscatter inspection device, a signal processing device, and an image processing device. The transmission inspection device comprises a transmission radiation source and a transmission detector which are arranged on two opposite sides of the inspection channel. The backscatter inspection device comprises a backscatter radiation source and a backscatter detector arranged on the same side of the inspection channel. The time at which the transmission radiation source outputs a transmission beam is staggered from the time at which the backscatter radiation source outputs a pencil beam. A backscatter signal correction device is in signal connection with the backscatter detector, and is configured to subtract, from a backscatter detection signal produced by the backscatter detector during output of the pencil beam, an afterglow signal generated on the backscatter detector by the transmission beam, thereby forming a corrected backscatter signal. A backscatter image processing device is in signal connection with the backscatter signal correction device, and is configured to form a backscatter image on the basis of the corrected backscatter signal.

Description

Radiation inspection system

[0001] Cross-references to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202411943554.5, filed on December 26, 2024, entitled "Radiation Inspection System", the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to the field of radiation inspection technology, and in particular to a radiation inspection system. Background Technology

[0004] Radiation inspection systems used for inspecting objects such as containers and vehicles can be divided into transmission inspection systems and backscatter inspection systems from the perspective of imaging principles.

[0005] A transmission inspection system includes a transmission inspection device and a transmission image processing device. The transmission inspection device includes a transmission X-ray source and a transmission detector located on opposite sides of the inspection channel. In the transmission inspection system, the transmission X-ray beam output from the transmission X-ray source passes through the object being inspected within the inspection channel, attenuates, and is detected by the transmission detector located on the other side of the object, thus obtaining a transmission detection signal. The transmission image processing device processes the transmission detection signal to obtain a transmission image. The transmission detection signal detected by the transmission detector reflects information such as the density and thickness of the object being inspected, and can display the internal structure of the object. Transmission inspection systems have the advantages of strong penetration and high image quality.

[0006] The backscattering inspection system includes a backscattering inspection device and a backscattering image processing device. The backscattering inspection device comprises a backscattering X-ray source and a backscattering detector located on the same side of the inspection channel. The backscattering inspection system utilizes the Compton scattering effect. A pencil-shaped X-ray beam is emitted from the backscattering X-ray source towards the object being inspected within the inspection channel. The backscattering detector, located on the same side of the backscattering X-ray source, captures the backscattered X-rays reflected from the object, thus obtaining a backscattering detection signal. The backscattering image processing device processes the backscattering detection signal to obtain a backscattering image. Because the Compton scattering of X-rays is stronger in low atomic number materials such as explosives and drugs, the backscattering system can distinguish materials and highlight organic substances.

[0007] Both transmission and backscattering inspection systems, from an imaging perspective, can be categorized into single-view and multi-view inspection systems. Multi-view radiation inspection systems, for example, can employ combinations of different perspectives such as side, top, and bottom views. Multi-view radiation inspection systems allow for a more comprehensive inspection of the object from various angles.

[0008] Transmission and backscattering inspection systems each have their advantages. A radiation inspection system integrating both technologies can provide both transmission and backscattering images after the inspection, thus combining the advantages of both. Furthermore, a multi-view radiation inspection within this integrated system offers the combined advantages of transmission, backscattering, and multi-view inspection.

[0009] Typically, detectors in radiation inspection systems exhibit a persistence effect. This persistence effect refers to the phenomenon where, after being exposed to light or radiation, a detector continues to emit a weak light or signal for a period of time, even in the absence of direct light or radiation. This persistence effect can cause unwanted, continuous light or signals in the image, thus affecting image quality.

[0010] In a radiation inspection system integrating two radiation inspection technologies, the transmitted X-ray beam output by the transmission X-ray source of the transmission inspection device is a high-energy beam with a large dose. If the backscatter detector is positioned to receive the transmitted X-ray beam (whether before or after attenuation), it will still generate an afterglow signal under the influence of the transmitted X-ray beam for a period of time after the beam stops outputting. Taking an accelerator that emits a pulsed beam as an example, even if the pulse width of the transmitted X-ray beam emitted by the accelerator is only 3-5 μs, if the distance between the backscatter inspection device and the transmission inspection device along the extension direction of the inspection channel is relatively close, placing the backscatter detector in a position to receive the transmitted X-ray beam, the backscatter detector will still be affected by that pulse after a certain pulse output by the accelerator, generating an afterglow signal.

[0011] In related technologies, in radiation inspection systems integrating two radiation inspection technologies, to avoid the transmitted radiation beam generated by the transmitted radiation source of the transmission inspection device affecting the backscatter detection signal of the backscatter detector of the backscatter inspection device, the transmission inspection device and the backscatter inspection device are usually separated by a certain distance along the extension direction of the inspection channel, typically more than 5 meters. This arrangement of the transmission and backscatter inspection devices results in an excessively large footprint for the radiation inspection system.

[0012] The above statements are for providing background information in connection with this disclosure only and do not necessarily constitute prior art. Summary of the Invention

[0013] The purpose of this disclosure is to provide a radiation inspection system that addresses the problem of excessive floor space required for radiation inspection systems integrating two radiation inspection technologies.

[0014] This disclosure provides a radiation inspection system having an inspection channel for the object to be inspected to pass through, including:

[0015] A transmission inspection apparatus, comprising a transmission radiation source and a transmission detector disposed on opposite sides of the inspection channel, is configured to perform transmission inspection on the object being inspected passing through the inspection channel; and

[0016] A backscattering inspection device includes a backscattering X-ray source and a backscattering detector disposed on the same side of the inspection channel, configured to perform backscattering inspection on the object being inspected passing through the inspection channel, wherein the timing of the transmission X-ray source outputting the transmission X-ray beam is staggered from the timing of the backscattering X-ray source outputting the pencil X-ray beam.

[0017] A backscattering signal correction device, signal-connected to the backscattering detector, is configured to subtract the afterglow signal generated by the transmitted beam from the transmitted beam source on the backscattering detector from the backscattering detection signal generated by the backscattering detector when the pencil beam is output, thereby forming a backscattering correction signal; and

[0018] A backscatter image processing device, signal-connected to the backscatter signal correction device, is configured to form a backscatter image based on the backscatter correction signal.

[0019] In some embodiments of the radiation inspection system,

[0020] The afterglow signal is formed based on pre-stored data in the backscatter signal correction device; or

[0021] The afterglow signal is obtained on-site by the backscatter detector when the transmitted X-ray beam output stops and the pencil X-ray beam is not output during the operation of the radiation inspection system.

[0022] In some embodiments of the radiation inspection system, the backscatter signal correction device acquires the afterglow signal multiple times on-site and generates a backscatter correction signal based on the most recently acquired afterglow signal.

[0023] In some embodiments of the radiation inspection system,

[0024] Each time the transmitted beam is output by the transmitted beam source, the backscatter signal correction device acquires the afterglow signal on-site once; or

[0025] The flying point device of the backscattered radiation source includes a fixed part and a movable part that moves periodically relative to the fixed part. Each time the movable part moves for one cycle, the backscattered signal correction device acquires the afterglow signal on site.

[0026] In some embodiments of the radiation inspection system,

[0027] The transmitted ray source outputs the transmitted ray beam in a pulsed manner;

[0028] The backscattered ray source outputs the pencil-shaped ray beam during the time interval between adjacent transmitted ray beams;

[0029] The backscatter signal correction device acquires the afterglow signal on-site based on the backscatter detection signal during the silent period when the backscatter detector stops outputting the pencil beam, excluding the interval between adjacent transmitted beams.

[0030] In some embodiments of the radiation inspection system, the backscattered X-ray source includes a radiation source and a flying point device. The flying point device includes a fixed part fixed relative to the radiation source and a movable part that periodically moves relative to the fixed part. The flying point device is configured to output or stop outputting the pencil-shaped X-ray beam through the relative movement of the fixed part and the movable part.

[0031] In some embodiments of the radiation inspection system, the backscatter signal correction device fits an afterglow attenuation curve based on the backscatter detection signal of the backscatter detector during the silent period, and generates the afterglow signal based on the afterglow attenuation curve.

[0032] In some embodiments of the radiation inspection system, the afterglow attenuation curve is I. t =I0e -t / τ ,in,

[0033] t is the fitting time;

[0034] It represents the afterglow signal at the fitting time t;

[0035] I0 is the backscattered detection signal at the fitting time t is zero;

[0036] τ is the decay time constant of the backscatter detector.

[0037] In some embodiments of the radiation inspection system, the transmission inspection device and the backscattering inspection device are configured such that the transmitted beam and the pencil beam are coplanar.

[0038] In some embodiments of the radiation inspection system, the radiation inspection system includes two or more backscattering inspection devices with different viewing angles and / or two or more transmission inspection devices with different viewing angles.

[0039] In some embodiments of the radiation inspection system, a pencil beam is output once or multiple times within the time interval between each adjacent transmitted beam.

[0040] In some embodiments of the radiation inspection system, multiple pencil beams are output within the time interval of each adjacent transmitted beam, wherein the output order of the multiple pencil beams is sorted from least to most affected by the afterglow signal of the transmitted beam to the backscatter detector receiving the pencil beams.

[0041] In some embodiments of the radiation inspection system, the backscatter detector includes a plastic scintillator or a GAGG crystal.

[0042] Based on the radiation inspection system provided in this disclosure, a backscatter signal correction device connected to the backscatter detector is provided. This device can subtract the afterglow signal generated by the transmitted X-ray beam output by the transmitted X-ray source from the backscatter detection signal generated by the backscatter detector to form a backscatter correction signal. The backscatter image processing device is connected to the backscatter signal correction device and forms a backscatter image based on the backscatter correction signal. Therefore, even if the backscatter detector is in a position where it can receive the transmitted X-ray beam, a relatively realistic backscatter image of the inspected object can still be obtained because the backscatter image is derived from the backscatter correction signal formed by subtracting the afterglow signal from the backscatter detection signal. As a result, the distance between the transmitted X-ray inspection device and the backscatter inspection device along the extension direction of the inspection channel can be set closer than in related technologies, thereby reducing the total length of the radiation inspection system along the extension direction of the inspection channel and helping to solve the problem of excessive floor space in radiation inspection systems integrating two radiation inspection technologies.

[0043] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0044] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this disclosure, illustrate exemplary embodiments of the present disclosure and are used to explain the disclosure, but do not constitute an undue limitation of the disclosure. In the drawings:

[0045] Figure 1 is a schematic block diagram of a radiation inspection system according to an embodiment of the present disclosure, wherein the radiation inspection system includes a transmission inspection device and a backscattering inspection device.

[0046] Figure 2 is a schematic diagram of the backscattering X-ray source of the backscattering inspection device of the radiation inspection system shown in Figure 1.

[0047] Figure 3 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection system of the embodiment shown in Figure 1.

[0048] Figure 4 is a schematic diagram of the afterglow attenuation curve fitted by the backscatter signal correction device of the radiation inspection system of the embodiment shown in Figure 1.

[0049] Figure 5 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the backscattering inspection device in an alternative embodiment of the radiation inspection system shown in Figure 1.

[0050] Figure 6 is a schematic diagram of the arrangement of the transmission inspection device and the backscatter inspection device of a radiation inspection system according to an embodiment of the present disclosure relative to the inspection channel, wherein the radiation inspection system includes one transmission inspection device and four backscatter inspection devices.

[0051] Figure 7 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection system of the embodiment shown in Figure 6.

[0052] Figure 8 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection device in an alternative embodiment of the radiation inspection system shown in Figures 6 and 7.

[0053] Figure 9 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection device in another alternative embodiment of the radiation inspection system shown in Figures 6 and 7.

[0054] Figure 10 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the backscattering inspection device, which is an alternative embodiment of the radiation inspection system shown in Figures 6 and 7.

[0055] Figure 11 is a schematic diagram of the arrangement of the transmission inspection device and the backscatter inspection device of a radiation inspection system according to an embodiment of the present disclosure relative to the inspection channel, wherein the radiation inspection system includes one transmission inspection device and three backscatter inspection devices.

[0056] Figure 12 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection system of the embodiment shown in Figure 11.

[0057] Figure 13 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection device in an alternative embodiment of the radiation inspection system shown in Figures 11 and 12.

[0058] Figure 14 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection device in another alternative embodiment of the radiation inspection system shown in Figures 11 and 12.

[0059] Figure 15 is a schematic diagram of the arrangement of the transmission inspection device and the backscatter inspection device of a radiation inspection system according to an embodiment of the present disclosure relative to the inspection channel, wherein the radiation inspection system includes one transmission inspection device and two backscatter inspection devices.

[0060] Figure 16 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection system of the embodiment shown in Figure 15.

[0061] Figure 17 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection device in an alternative embodiment of the radiation inspection system shown in Figures 15 and 16.

[0062] Figure 18 is a timing diagram of the transmission beam emitted by the transmission beam source of the transmission inspection device and the pencil beam output by the backscattering beam source of the radiation inspection device in another alternative embodiment of the radiation inspection system shown in Figures 15 and 16. Detailed Implementation

[0063] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0064] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0065] In the description of this disclosure, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this disclosure.

[0066] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0067] Furthermore, the technical features involved in the different embodiments of this disclosure described below can be combined with each other as long as they do not conflict with each other.

[0068] This disclosure provides a radiation inspection system having an inspection channel P for the object to be inspected to pass through, including a transmission inspection device 10, a backscatter inspection device 20, a signal processing device, and an image processing device.

[0069] The transmission inspection device 10 includes a transmission radiation source 11 and a transmission detector 12 disposed on opposite sides of the inspection channel P, and is configured to perform transmission inspection on the object being inspected as it passes through the inspection channel P.

[0070] The backscattering inspection device 20 includes a backscattering X-ray source 21 and a backscattering detector 22 disposed on the same side of the inspection channel P, and is configured to perform backscattering inspection on the object being inspected passing through the inspection channel P. The timing of the transmission X-ray source 11 outputting the transmission X-ray beam is staggered from the timing of the backscattering X-ray source 21 outputting the pencil-shaped X-ray beam.

[0071] The backscattering signal correction device 30 is signal-connected to the backscattering detector 22 and is configured to subtract the afterglow signal generated by the transmitted ray beam output by the transmitted ray source 11 on the backscattering detector 22 from the backscattering detection signal generated by the backscattering detector 22 when the pencil ray beam is output, thereby forming a backscattering correction signal.

[0072] The backscatter image processing device 50 is signal-connected to the backscatter signal correction device 30 and is configured to form a backscatter image based on the backscatter correction signal.

[0073] In a radiation inspection system integrating both transmission and backscattering radiation inspection technologies, if the backscatter detector 22 is positioned to receive the transmitted radiation beam, when the backscatter inspection device 20 begins scanning—that is, when the pencil-shaped radiation beam output from the backscatter source scans the object being inspected—the backscatter detector of the backscatter inspection device 20 begins to collect the backscattered radiation from the object. Due to the afterglow effect, the backscatter detection signal output by the backscatter detector 22 still includes the afterglow signal generated by the transmitted radiation beam output from the transmission source 11 on the backscatter detector. During the inspection operation of the backscatter inspection device 20, the backscatter detection signal of the backscatter detector 22 contains both the actual backscatter signal and the afterglow signal generated by the afterglow effect of the transmitted radiation beam. Therefore, the backscatter detection signal of the backscatter detector 22 cannot accurately reflect the backscatter signal of the object being inspected. In other words, even when the transmission source 11 is not outputting a beam, the backscatter detection signal output by the backscatter detector 22 still includes the afterglow signal affected by the transmitted radiation beam generated by the transmission source 11. If the backscatter detector 22 uses a crystal with a long afterglow decay time (such as BaFCl), the backscatter detection signal output by the backscatter detector 22 will be more severely affected by the afterglow from the transmitted beam.

[0074] In the radiation inspection system of this embodiment, a backscatter signal correction device 30 connected to the backscatter detector 22 is provided. The backscatter signal correction device 30 can subtract the afterglow signal generated by the transmitted X-ray beam output by the transmitted X-ray source 11 on the backscatter detector 22 from the backscatter detection signal generated by the backscatter detector 22 to form a backscatter correction signal. The backscatter image processing device 50 is connected to the backscatter signal correction device 30 and forms a backscatter image based on the backscatter correction signal. Therefore, even if the backscatter detector 22 is in a position that can receive the transmitted X-ray beam, since the backscatter image is obtained from the backscatter correction signal formed by subtracting the afterglow signal from the backscatter detection signal, a relatively realistic backscatter image of the inspected object can still be obtained. As a result, the distance between the transmitted X-ray inspection device 10 and the backscatter inspection device 20 along the extension direction of the inspection channel P can be set closer than in related technologies, thereby reducing the total length of the radiation inspection system along the extension direction of the inspection channel P and helping to solve the problem of excessive floor space in radiation inspection systems integrating two radiation inspection technologies.

[0075] In some embodiments of the radiation inspection system, the afterglow signal is formed based on pre-stored data in the backscatter signal correction device 30; or the afterglow signal is obtained on-site based on the backscatter detection signal of the backscatter detector when the transmitted X-ray beam output stops and the pencil X-ray beam is not output during the operation of the radiation inspection system.

[0076] The afterglow signal is formed based on pre-stored data in the backscatter signal correction device 30. The afterglow signal generated by the transmitted X-ray source 11 on the backscatter detector 22 can be tested in advance and stored in the storage unit of the backscatter signal correction device 30. When forming the backscatter imaging signal, the backscatter signal correction device 30 directly retrieves the afterglow signal stored in the storage unit. When the pencil beam is output, the afterglow signal generated by the transmitted X-ray beam output by the transmitted X-ray source 11 on the backscatter detector 22 is subtracted from the backscatter detection signal generated by the backscatter detector 22 to form the backscatter correction signal. For example, during advance testing, the afterglow signal test can begin immediately after the transmitted X-ray source 11 stops emitting the transmitted X-ray beam, and end after the test lasts for a period covering the time when the backscatter source 21 emits the pencil beam. After obtaining a series of test data, supplementary data can be generated by forming a fitting curve or using interpolation to obtain the afterglow signal for the entire test period. Obtaining the afterglow signal in this way yields a more accurate backscatter correction signal, making the backscatter image derived from the backscatter correction signal more realistic. If the parameters of the transmitted X-ray beam emitted by the transmitted X-ray source 11 are adjustable, multiple sets of afterglow signals corresponding to the parameters of the transmitted X-ray beam can be tested. When the backscatter signal correction device 30 retrieves the afterglow signal in the storage device, it needs to call up the afterglow signal corresponding to the parameters of the transmitted X-ray beam.

[0077] The afterglow signal is obtained on-site from the backscatter detection signal of the backscatter detector when the transmitted X-ray beam output stops and the pencil X-ray beam is not output during the operation of the radiation inspection system. It is beneficial to form the afterglow signal based on the influence of the transmitted X-ray beam detected in real time by the backscatter detector. The afterglow signal obtained on-site can follow the parameters of the transmitted X-ray beam when the radiation inspection system is working, so as to obtain a more accurate backscatter correction signal, making the backscatter image obtained from the backscatter correction signal more realistic.

[0078] For example, to obtain the afterglow signal on-site, the backscattering source can stop outputting a pencil beam during the interval between two transmission beams emitted by the transmission source 11. The backscattering detector's backscattering signal detected during this interval is the afterglow signal formed by the influence of the transmission beam emitted before the interval. After obtaining the afterglow signal, this afterglow signal can be used to obtain the backscattering correction signal when the backscattering source is normally outputting a pencil beam. In this way, the afterglow signal obtained on-site is complete and accurate, the obtained backscattering correction signal is relatively accurate, and the resulting backscattering image is more realistic.

[0079] In some embodiments of the radiation inspection system, the backscatter signal correction device acquires afterglow signals on-site more than 30 times and generates a backscatter correction signal based on the most recently acquired afterglow signal.

[0080] The backscatter signal correction device acquires afterglow signals on site more than 30 times and generates a backscatter correction signal based on the most recent afterglow signal. This allows for the generation of a backscatter correction signal based on the afterglow signal generated by the parameters of the transmitted X-ray beam, thereby obtaining a more realistic backscatter image.

[0081] In some embodiments of the radiation inspection system, the backscatter signal correction device 30 acquires an afterglow signal once for each time the transmitted X-ray source 11 outputs a transmitted X-ray beam; or the flying point device 212 of the backscatter X-ray source 21 includes a fixed part 2121 and a movable part 2122 that moves periodically relative to the fixed part 2121, and the backscatter signal correction device 30 acquires an afterglow signal once for each cycle of movement of the movable part 2122.

[0082] The frequency settings for the on-site acquisition of the afterglow signal are all conducive to the afterglow signal following the parameters of the transmitted ray velocity in a timely manner, thereby facilitating the formation of a more realistic backscatter correction signal based on the parameters of the transmitted ray beam, and thus obtaining a more realistic backscatter image.

[0083] In some embodiments of the radiation inspection system, the transmitted X-ray source 11 outputs a transmitted X-ray beam in a pulsed manner; the backscattered X-ray source 21 outputs a pencil-shaped X-ray beam during the interval between adjacent transmitted X-ray beams; and the backscattered signal correction device 30 obtains the afterglow signal on-site based on the backscattered detection signal during the silent period when the backscattered detector 22 stops outputting the pencil-shaped X-ray beam, other than the interval between adjacent transmitted X-ray beams.

[0084] In this embodiment of the radiation inspection system, the backscattering source does not emit a pencil beam during a silent period within the interval between two transmission beams emitted by the transmission source 11, while the remaining time period is the normal output period of the pencil beam from the backscattering source. The backscattering detection signal detected by the backscattering detector 22 during this silent period within the interval is the afterglow signal formed by the backscattering detector 22 under the influence of the transmission beam emitted before the interval. The afterglow signal during the output period within the interval is derived from the afterglow signal during the silent period. After obtaining the afterglow signal during the output period within the interval, the afterglow signal during the output period can be used when acquiring the backscattering correction signal when the backscattering source 21 normally outputs the pencil beam. Using this method to obtain the afterglow signal during the inspection does not require stopping the backscattering source to output the pencil beam. With a relatively accurate backscattering correction signal and a relatively realistic backscattering image, the radiation inspection does not need to be interrupted, thus resulting in high efficiency.

[0085] In some embodiments of the radiation inspection system, the backscattered X-ray source 21 includes a radiation source 211 and a flying point device 212. The flying point device 212 includes a fixed part 2121 fixed relative to the radiation source 211 and a movable part 2122 that periodically moves relative to the fixed part 2121. The flying point device 212 is configured to output or stop outputting a pencil-shaped X-ray beam through the relative movement of the fixed part 2121 and the movable part 2122.

[0086] The flying point device 212 is configured to output or stop the output of a pencil-shaped beam by the relative movement of the fixed part 2121 and the movable part 2122. By means of the structural arrangement of the fixed part 2121 and the movable part 2122 of the flying point device 212, it is possible to achieve the goal of not having to control the silent period and the beam output period of the backscattered beam source in order to obtain the afterglow signal on site, so as not to increase the complexity of backscattered beam source control due to obtaining the afterglow signal on site.

[0087] In some embodiments of the radiation inspection system, the backscatter signal correction device 30 fits the afterglow attenuation curve based on the backscatter detection signal of the backscatter detector 22 during the silent period, and forms the afterglow signal based on the afterglow attenuation curve.

[0088] The afterglow attenuation curve is fitted by the backscatter detection signal of the backscatter detector 22 during the silent period. The afterglow signal during the beam time period can be formed by the afterglow attenuation curve, so as to obtain a more accurate backscatter correction signal and a more realistic backscatter image.

[0089] In some embodiments of the radiation inspection system, the afterglow attenuation curve is I t =I0e -t / τ ,in,

[0090] t is the fitting time;

[0091] It represents the afterglow signal at the fitting time t;

[0092] I0 is the backscattered detection signal at the fitting time t is zero;

[0093] τ is the decay time constant of the backscatter detector 22.

[0094] Afterglow decay curve set to I t =I0e -t / τ The fitted curve is applicable to a wide variety of detectors and has a good fitting effect, resulting in a more accurate afterglow signal. This is beneficial for obtaining a more accurate backscatter correction signal and a more realistic backscatter image.

[0095] In some embodiments of the radiation inspection system, the transmission inspection device 10 and the backscatter inspection device 20 are configured such that the transmission beam and the pencil beam are coplanar.

[0096] The transmission inspection device 10 and the backscatter inspection device 20 are configured such that the transmitted X-ray beam and the pencil X-ray beam are coplanar. This minimizes the space occupied by the transmission inspection device 10 and the backscatter inspection device 20 along the extension direction of the inspection channel P, thereby maximizing the reduction of the total length of the radiation inspection system along the extension direction of the inspection channel P and more effectively solving the problem of excessive floor space in radiation inspection systems integrating two radiation inspection technologies. As is generally understood in the art, coplanarity in this disclosure means that the scanning plane of the transmission X-ray beam and the scanning plane of the pencil X-ray beam are coplanar or substantially coplanar. In some embodiments of the radiation inspection system, the radiation inspection system includes two or more backscatter inspection devices 20 with different viewing angles and / or two or more transmission inspection devices 10 with different viewing angles. Furthermore, if the transmission inspection device 10 and the backscatter inspection device 20 are separated by a certain distance, the transmission image and the backscatter image need to be aligned and registered so that each position of the two images corresponds to each other, facilitating comparison and viewing of the two images at the same position of the inspected object. Since the transmission inspection device 10 and the backscatter inspection device 20 are configured such that the transmission beam and the pencil beam are coplanar, no alignment and registration operation is required, and the two images at the same position can be directly compared and viewed.

[0097] The radiation inspection system includes two or more backscatter inspection devices 20 with different viewing angles and / or two or more transmission inspection devices 10 with different viewing angles. This allows for a further concentration of the advantages of multi-view radiation inspection in a radiation inspection system that integrates two radiation inspection technologies. Furthermore, since the influence of the afterglow signal is subtracted from the backscatter detection signal, even though the radiation inspection system includes two or more backscatter inspection devices 20 with different viewing angles and / or two or more transmission inspection devices 10 with different viewing angles, the footprint will not increase due to multi-view inspection. Thus, the problem of excessive footprint in a radiation inspection system integrating two radiation inspection technologies can still be solved by using multi-view radiation inspection technology.

[0098] In some embodiments of the radiation inspection system, a pencil beam is output once or multiple times within the time interval between each adjacent transmitted beam.

[0099] The system outputs one or multiple pencil beams within the interval between each adjacent transmitted X-ray beam. The inspection time of the transmission inspection device and the backscattering inspection device can be reasonably allocated according to the output frequency of the transmitted X-ray beam and the output frequency of the pencil beam, which helps to improve the inspection efficiency of the radiation inspection system.

[0100] In some embodiments of the radiation inspection system, multiple pencil beams are output within the time interval of each adjacent transmitted beam, wherein the output order of the multiple pencil beams is sorted from least to most affected by the afterglow signal of the transmitted beams on the backscatter detector 22 receiving the pencil beams.

[0101] The output order of multiple pencil beams is arranged from least to most affected by the afterglow signal of the transmitted beam to the backscatter detector 22 receiving the pencil beam. This helps to minimize the impact of the afterglow signal on the backscatter detection signal of each backscatter detector 22, thereby facilitating the acquisition of more accurate backscatter correction signals and more realistic backscatter images.

[0102] In some embodiments of the radiation inspection system, the backscatter detector 22 includes a plastic scintillator or a GAGG crystal.

[0103] Plastic scintillators or GAGG (gadolinium gallium aluminum garnet) crystals have shorter afterglow decay times compared to other types of backscatter detectors 22, which helps to further reduce the deviation between the backscatter correction signal and the true backscatter signal of the pencil beam completely reflected by the object being inspected, thereby making the backscatter image more realistic.

[0104] The radiation inspection system of the present disclosure will be described in detail below with reference to Figures 1 to 18.

[0105] Figure 1 is a schematic block diagram of a radiation inspection system according to an embodiment of the present disclosure. This radiation inspection system integrates both transmission and backscattering radiation inspection technologies. Both the transmission and backscattering inspection devices are single-viewpoint radiation inspection systems, suitable for radiation scanning inspection of objects such as containers or vehicles.

[0106] As shown in Figure 1, the radiation inspection system of this embodiment has an inspection channel P for the object to be inspected to pass through, including a transmission inspection device 10, a backscatter inspection device 20, a backscatter signal correction device 30, a transmission image processing device 40, a backscatter image processing device 50, a display device 60, and a control device 70.

[0107] The transmission inspection device 10 includes a transmission X-ray source 11 and a transmission detector 12 disposed on opposite sides of the inspection channel P, and is configured to perform transmission inspection on the object being inspected passing through the inspection channel P. The transmission inspection device 10 may, for example, use an accelerator or an isotope source as the transmission X-ray source 11. The high-energy X-rays emitted by the accelerator or the Gamma rays emitted by the isotope source serve as the transmission X-ray beam. After attenuation upon passing through the object being inspected in the inspection channel P, the beam is detected by the transmission detector 12 located on the other side of the object being inspected, thus forming a transmission detection signal.

[0108] The backscattering inspection apparatus 20 includes a backscattering X-ray source 21 and a backscattering detector 22 disposed on the same side of the inspection channel P, and is configured to perform backscattering inspection on the object being inspected passing through the inspection channel P. The backscattering detector 22 includes a plastic scintillator or a GAGG crystal.

[0109] The transmission inspection device 10 and the backscatter inspection device 20 are configured such that the transmission beam and the pencil beam are coplanar. The exit scanning directions of both the transmission beam and the pencil beam are directed towards the scanning channel P and perpendicular to the extension direction of the scanning channel P.

[0110] Figure 2 is a schematic diagram of the backscattering X-ray source 21 of the backscattering X-ray inspection device 20 of the radiation inspection system shown in Figure 1.

[0111] As shown in Figure 2, the backscattered X-ray source 21 includes a radiation source 211 and a flying-spot device 212. The flying-spot device 212 includes a fixed part 2121 fixed relative to the radiation source 211 and a movable part 2122 that periodically moves relative to the fixed part 2121. The flying-spot device 212 is configured to output or stop outputting a pencil-shaped X-ray beam through the relative movement of the fixed part 2121 and the movable part 2122. The radiation source 211 is, for example, an X-ray source.

[0112] As shown in Figure 2, in this embodiment of the present disclosure, the fixed part 2121 is a sector-shaped box, and the beam exit position of the radiation source 211 is set at the radial center of the sector-shaped box. The movable part 2122 includes a rotating ring, on which a beam hole 21221 is provided. The movable part 2122 is sleeved on the outside of the sector-shaped box, and the radial outer side of the sector-shaped box has an arc-shaped groove with the same diameter as the rotating ring. The movable part 2122 is rotatably arranged around the center of the rotating ring.

[0113] As shown in Figure 2, in this embodiment of the present disclosure, the sector-shaped box and the rotating ring are eccentrically arranged, and the sector-shaped box is centered at an angle of 90° with respect to the beam exit point G of the radiation source 211. In embodiments not shown, the sector-shaped box and the rotating ring may be concentrically arranged.

[0114] In Figure 2, the rotating ring has three beam apertures 21221 spaced at 120° intervals. Therefore, with each rotation of the rotating ring, the three beam apertures 21221 pass through the arc-shaped slot of the fan-shaped box once in sequence, and the pencil-shaped X-ray beam is output three times, that is, the backscattered X-ray source completes three scans.

[0115] When the backscatter inspection device 20 performs radiation scanning inspection, the X-ray beam from the X-ray source is collimated into a pencil beam through the fan-shaped box and beam aperture 21221. During the high-speed rotation of the rotating ring, only one beam aperture 21221 can emit the pencil beam at any given time. The pencil beam is a thin beam of X-rays that performs a one-dimensional high-speed linear scan in the vertical direction. Simultaneously, the object under inspection moves within the inspection channel P along the extension direction of the inspection channel P, generating relative motion with the radiation inspection system. The backscatter detector detects the backscattered rays reflected from the object under inspection, thereby obtaining a two-dimensional backscattered image of the object under inspection based on the backscatter detection signal detected by the backscatter detector.

[0116] As shown in Figure 3, the timing of the transmission beam output by the transmission source 11 is staggered from the timing of the pencil beam output by the backscattering source 21.

[0117] As shown in Figure 1, the backscatter signal correction device 30 is signal-connected to the backscatter detector 22. The backscatter signal correction device 30 is configured to subtract the afterglow signal generated by the transmitted X-ray beam output from the transmitted X-ray source 11 on the backscatter detector 22 from the backscatter detection signal generated by the backscatter detector 22 to form a backscatter correction signal.

[0118] In this embodiment, the afterglow signal is acquired on-site based on the backscatter detection signal of the backscatter detector when the transmitted X-ray beam output stops and the pencil X-ray beam is not output during the operation of the radiation inspection system. The backscatter signal correction device 30 acquires the afterglow signal on-site more than 30 times and forms a backscatter correction signal based on the most recent on-site acquired afterglow signal. Every time the transmitted X-ray source 11 outputs the transmitted X-ray beam, the backscatter X-ray source 21 outputs the pencil X-ray beam once, and the backscatter signal correction device 30 acquires the afterglow signal on-site once.

[0119] The transmitted X-ray source 11 is an accelerator that outputs a transmitted X-ray beam in a pulsed manner. The backscattered X-ray source 21 outputs a pencil-shaped X-ray beam during the interval between adjacent transmitted X-ray beams. The backscattered signal correction device 30 obtains the afterglow signal on-site based on the backscattered detection signal during the silent period when the backscattered detector 22 stops outputting the pencil-shaped X-ray beam, excluding the interval between adjacent transmitted X-ray beams.

[0120] As shown in Figure 3, the pulse frequency of the accelerator's output transmitted X-ray beam is 100 Hz, the pulse width is 3–5 μs, and the time interval between two adjacent pulses, i.e., between two adjacent output transmitted X-ray beams, is approximately 10 ms. The vertical lines in Figure 3 qualitatively indicate the relative magnitude of the energy E of the accelerator's output transmitted X-ray beam.

[0121] As shown in Figures 2 and 3, the rotating ring of the flying point device 212 of the backscattered X-ray source 21 has three beam apertures 21221, operating at a rotation speed of 2000 rpm, meaning one rotation takes 30 ms. The backscattered X-ray source 21 scans one column in 10 ms. Centered on the exit point G of the radiation source 211, the angle of the sector box is 90°, and the angle of the arc-shaped slot is 87°. Each beam aperture 21221 passes through the arc-shaped slot of the sector box once, resulting in a 3° blind zone with no pencil-shaped X-ray beam output. The time period during which the beam aperture 21221 passes through the arc-shaped slot of the sector box is the beam output time period, and the time period during which the beam aperture 21221 passes through the blind zone is the silent time period. The beam output time period for each backscattered X-ray source outputting a pencil-shaped X-ray beam is 9.67 ms, with a corresponding silent time period of 0.33 ms. During the silent period of 0.33 ms, neither the transmitted X-ray source 11 nor the backscattered X-ray source 21 outputs a pencil-shaped X-ray beam. It is understandable that the relative magnitudes of the beam-out time and the silent period can be adjusted according to the angle of the arc-shaped slot in the sector box. In Figure 3, the shading qualitatively indicates the relative magnitude of the energy E of the pencil-shaped X-ray beam output by the backscattered X-ray source 21 during the beam-out time.

[0122] The backscatter detector 22 acquires backscatter detection signals at a certain sampling interval during the time interval between two pulses. Among them, the backscatter detection signal obtained during the 0.33ms silent period is the afterglow signal of the silent period, and the backscatter detection signal obtained during the 9.67ms beam-out period is the total signal of the superposition of the backscatter signal and the afterglow signal of the beam-out period.

[0123] In this embodiment of the disclosure, the backscatter signal correction device 30 fits the afterglow attenuation curve based on the backscatter detection signal obtained within the silent period of 0.33ms, thereby obtaining the afterglow signal within the beam-out period of 9.67ms. The backscatter correction signal is formed by subtracting the afterglow signal at the corresponding time point from the backscatter detection signal generated by the backscatter detector 22 within the beam-out period of 9.67ms.

[0124] As shown in Figure 4, the backscatter signal correction device 30 fits the afterglow attenuation curve based on the backscatter detection signal of the backscatter detector 22 during the silent period, and forms the afterglow signal based on the afterglow attenuation curve.

[0125] In this embodiment, the backscatter signal correction device 30 fits the afterglow attenuation curve more than 30 times and forms an afterglow signal based on the most recently fitted afterglow attenuation curve. Each time the transmitted X-ray source 11 outputs a transmitted X-ray beam, and each time the backscatter X-ray source 21 outputs a pencil-shaped X-ray beam, the backscatter signal correction device 30 fits the afterglow attenuation curve once.

[0126] Afterglow decay curve is I t =I0e -t / τ Where t is the fitting time; It is the afterglow signal at fitting time t; I0 ​​is the backscattered detection signal when fitting time t is zero; and τ is the decay time constant of the backscattered detector 22. τ can be calculated from the backscattered detection signals corresponding to multiple measurement times t during the silent period. Different types of detectors have different decay time constants.

[0127] In other words, after the accelerator finishes one transmission beam exit, i.e., at time 0 in Figure 4, during the silent period before the backscattered beam source 21 exits, the backscatter detector 22 collects data at certain time intervals. The afterglow decay curve I is then fitted using the backscattered detection signals collected during the silent period. t =I0e -t / τAfter the backscattered X-ray source 21 begins to emit its beam, the backscattered detection signal output by the backscatter detector 22 includes a backscattered signal and an afterglow signal. Subtracting the fitted afterglow signal based on the fitted curve at the same moment from the backscattered detection signal during the beam emission period yields the required backscattered correction signal. In Figure 4, time t1 represents the start time of beam emission from the backscattered X-ray source 21, and time t2 represents the end time of beam emission from the backscattered X-ray source 21. In this embodiment, t1 is 0.33 ms and t2 is 10 ms.

[0128] Even when the afterglow signal is subtracted using a fitted afterglow decay curve, the fitted afterglow decay curve will inevitably deviate from the actual afterglow signal. In this embodiment, a plastic scintillator or GAGG crystal is selected to form the backscatter detector 22, which has a short afterglow decay time, resulting in a more realistic backscatter image.

[0129] As shown in Figure 1, the transmission image processing device 40 is signal-connected to the transmission detector 12 and is configured to form a transmission image based on the transmission detection signal.

[0130] As shown in Figure 1, the backscatter image processing device 50 is connected to the backscatter signal correction device 30 and is configured to form a backscatter image based on the backscatter correction signal.

[0131] The display device 60 is signal-connected to the transmission image processing device 40 and the backscatter image processing device 50, and is used to display transmission images and backscatter images.

[0132] The control device 70 is signal-connected to the transmitted X-ray source 11 and the backscattered X-ray source 21, and is used to control the output parameters of the transmitted X-ray source 11 and the backscattered X-ray source 21. The output parameters include, for example, the output time and the output frequency.

[0133] The control device 70 may be implemented as a general-purpose processor, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any suitable combination thereof for performing the functions described in this disclosure.

[0134] Figure 5 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20 in an alternative embodiment of the radiation inspection system shown in Figure 1.

[0135] As shown in Figure 5, in this embodiment, the transmitted X-ray source 11 is an accelerator that outputs a transmitted X-ray beam in a pulsed manner. The accelerator outputs the transmitted X-ray beam with alternating high and low pulses, both at a frequency of 200 Hz and a pulse width of 3–5 μs. The interval between two adjacent high and low pulses is approximately 2.5 ms.

[0136] The flying point device 212 of the backscattered X-ray source 21 has four beam apertures 21221 on its rotating ring, operating at a speed of 6000 rpm. A sector box is concentrically positioned with the rotating ring, with an angle of 90°, allowing the flying point device 212 to emit a pencil-shaped X-ray beam four times per revolution of the rotating ring. The angle of the arc-shaped slot is 86°. Each beam aperture 21221 passes through the arc-shaped slot of the sector box once, resulting in a 4° blind zone with no pencil-shaped X-ray beam output. The backscattered X-ray source 21 can complete a series of backscattered X-ray acquisitions within the 2.5ms interval between two adjacent high and low pulses emitted by the transmitted X-ray source. Therefore, the emission time of each pencil-shaped X-ray beam is 2.39ms, corresponding to a silent period of 0.11ms during which neither the transmitted X-ray source 11 nor the backscattered X-ray source 21 emits a beam.

[0137] The backscatter detector 22 acquires backscatter detection signals at a certain sampling interval during the time interval between two pulses. Among them, the backscatter detection signal obtained during the 0.11ms silent period is the afterglow signal of the silent period, and the backscatter detection signal obtained during the 2.39ms beam-out period is the total signal of the superposition of the backscatter signal and the afterglow signal of the beam-out period.

[0138] The backscatter signal correction device 30 fits the afterglow attenuation curve based on the backscatter detection signal obtained within the silent period of 0.11ms, thereby obtaining the afterglow signal within the beam-out period of 2.39ms. The backscatter correction signal is formed by subtracting the afterglow signal at the corresponding time point from the backscatter detection signal generated by the backscatter detector 22 within the beam-out period of 2.39ms.

[0139] For any parts not described in the embodiments corresponding to Figure 5, please refer to the relevant descriptions of the embodiments corresponding to Figures 1 to 4.

[0140] Figures 6 to 18 illustrate, for example, a multi-view radiation inspection system integrating both transmission and backscattering radiation inspection techniques in some embodiments, using multiple backscattering inspection devices to form a multi-view system.

[0141] Figure 6 is a schematic diagram of the arrangement of the transmission inspection device and the backscattering inspection device relative to the inspection channel of a radiation inspection system according to an embodiment of the present disclosure, wherein the radiation inspection system includes one transmission inspection device and four backscattering inspection devices. Figure 7 is a timing diagram of the transmission beam emitted by the transmission X-ray source 11 of the transmission inspection device of the radiation inspection system shown in Figure 6 and the pencil-shaped X-ray beam output by the backscattering X-ray source 21 of the backscattering inspection device 20.

[0142] As shown in Figure 6, the radiation inspection system includes one transmission inspection device and four backscattering inspection devices. The transmission X-ray source 11 of the transmission inspection device is located on the right side of the inspection channel P, and the transmission detector 12 is located on the left side of the inspection channel P. The four backscattering inspection devices are: a first backscattering inspection device 20A located above the transmission detector 12 on the left side of the inspection channel P (left-angle view); a second backscattering inspection device 20B located above the transmission X-ray source 11 on the right side of the inspection channel P (right-angle view); a third backscattering inspection device 20C located above the inspection channel P (top-angle view); and a fourth backscattering inspection device 20D located below the inspection channel P (bottom-angle view).

[0143] The first backscattering inspection device 20A includes a first backscattering X-ray source 21A and a second backscattering detector 22A. The second backscattering inspection device 20B includes a second backscattering X-ray source 21B and a second backscattering detector 22B. The third backscattering inspection device 20C includes a third backscattering X-ray source 21C and a third backscattering detector 22C. The fourth backscattering inspection device 20D includes a fourth backscattering X-ray source 21D and a fourth backscattering detector 22D. The exit directions of the transmitted X-ray beam emitted by the transmitted X-ray source 11 and the pencil-shaped X-ray beam emitted by the backscattering X-ray sources of the backscattering inspection devices at each viewing angle are all directed towards the scanning channel P and perpendicular to the extension direction of the scanning channel P.

[0144] In Figure 7, the vertical lines qualitatively indicate the relative magnitude of the energy E of the transmitted X-ray beam output by the accelerator, and the shading qualitatively indicates the relative magnitude of the energy E of the pencil-shaped X-ray beam output by the backscattered X-ray sources at each viewing angle during the beam exit time period. Furthermore, in order to distinguish between the transmitted X-ray beam emitted by the transmitted X-ray source and the pencil-shaped X-ray beam emitted by the backscattered X-ray sources at each viewing angle, the transmitted X-ray beam is labeled "transmitted", the pencil-shaped X-ray beam emitted by the first backscattered X-ray source 21A is labeled "backscattered 1", the pencil-shaped X-ray beam emitted by the second backscattered X-ray source 21B is labeled "backscattered 2", the pencil-shaped X-ray beam emitted by the third backscattered X-ray source 21C is labeled "backscattered 3", and the pencil-shaped X-ray beam emitted by the fourth backscattered X-ray source 21D is labeled "backscattered 4".

[0145] As shown in Figure 7, in this embodiment, between every two pulses of the accelerator that serves as the transmission X-ray source 11, only the backscattered X-ray source of the backscattered inspection device at a certain angle emits a beam, and the backscattered X-ray sources at each angle emit beams in turn in the order of the first backscattered X-ray source 21A, the second backscattered X-ray source 21B, the third backscattered X-ray source 21C, and the fourth backscattered X-ray source 21D.

[0146] In this embodiment, for each time the transmitted X-ray source 11 outputs a transmitted X-ray beam, the backscattered X-ray source 21 outputs a pencil-shaped X-ray beam, and the backscattered signal correction device 30 acquires an afterglow signal on site.

[0147] For any parts not described in the embodiments corresponding to Figures 6 and 7, please refer to the relevant descriptions in other embodiments.

[0148] Figure 8 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20, which is an alternative embodiment of the radiation inspection system shown in Figures 6 and 7.

[0149] As shown in Figure 8, the difference between this embodiment and the radiation inspection system shown in Figures 6 and 7 lies in the different beam emission methods of the transmitted X-ray source and the backscattered X-ray source at each viewing angle.

[0150] In the embodiment shown in Figure 8, in order to reduce the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewing angle, the radiation scan of the backscatter inspection device at two viewing angles is completed between the pulses of the two transmitted X-ray beams, that is, within a time interval. The backscatter X-ray sources at each viewing angle are emitted in turn in the order of the first backscatter X-ray source 21A, the second backscatter X-ray source 21B, the third backscatter X-ray source 21C, and the fourth backscatter X-ray source 21D.

[0151] In this embodiment, the backscatter signal correction device 30 acquires an afterglow signal once every time the transmitted ray source 11 outputs a transmitted ray beam.

[0152] For any parts not described in the embodiments corresponding to Figure 8, please refer to the relevant descriptions in other embodiments.

[0153] Figure 9 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20 in another alternative embodiment of the radiation inspection system shown in Figures 6 and 7.

[0154] As shown in Figure 9, the difference between this embodiment and the radiation inspection system shown in Figures 6 and 7 lies in the different beam emission methods of the transmitted X-ray source and the backscattered X-ray source at each viewing angle.

[0155] In the embodiment shown in Figure 9, in order to reduce the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewing angle, the radiation scan of the backscatter inspection device at four viewing angles is completed between the pulses of the two transmitted X-ray beams, that is, within a time interval. The backscatter X-ray sources at each viewing angle are emitted in turn in the order of the first backscatter X-ray source 21A, the second backscatter X-ray source 21B, the third backscatter X-ray source 21C, and the fourth backscatter X-ray source 21D.

[0156] In this embodiment, the backscatter signal correction device 30 acquires an afterglow signal once every time the transmitted ray source 11 outputs a transmitted ray beam.

[0157] For any parts not described in the embodiments corresponding to Figure 9, please refer to the relevant descriptions in other embodiments.

[0158] Figure 10 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20, which is another alternative embodiment of the radiation inspection system shown in Figures 6 and 7.

[0159] As shown in Figure 10, the difference between this embodiment and the radiation inspection system shown in Figures 6 and 7 lies in the different beam emission methods of the transmitted X-ray source and the backscattered X-ray source at each viewing angle.

[0160] In the embodiment shown in Figure 10, in order to reduce the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewing angle, the radiation scan of the backscatter inspection device at four viewing angles is completed between the pulses of the two transmitted X-ray beams, that is, within a time interval. The backscatter X-ray sources at each viewing angle are emitted in turn in the order of the third backscatter X-ray source 21C, the fourth backscatter X-ray source 21D, the second backscatter X-ray source 21B, and the first backscatter X-ray source 21A.

[0161] Because the backscattering inspection devices are positioned differently at different angles, the afterglow effect of the transmission inspection device 10 varies for each backscattering detector. Activating the backscattering inspection device 20 least affected by afterglow first, and then activating the one most affected last, allows for more afterglow attenuation time for the most affected device. That is, when multiple pencil beams are output within the interval between adjacent transmission beams, the output order of the multiple pencil beams is sorted from least to most affected by the afterglow signal of the transmission beam to the backscattering detector 22 receiving the pencil beams.

[0162] In this embodiment, the third backscatter detector 22C and the fourth backscatter detector 22D are located on the upper and lower sides of the transmitted X-ray source 11, thus the afterglow effect on the third backscatter detector 22C and the fourth backscatter detector 22D is relatively low. The relative level of the afterglow effect on the third backscatter detector 22C and the fourth backscatter detector 22D is affected by factors such as the distance from the transmitted X-ray source in the height direction and the scanning angle of the transmitted X-ray source. In this embodiment, the afterglow effect on the fourth backscatter detector 22D is higher than that on the third backscatter detector 22C. The second backscatter detector 22B is located on the same side of the transmitted X-ray source 11 and is affected by the afterglow of the backscattered X-rays generated after the transmitted X-ray beam irradiates the object being inspected. The effect is higher than that on the fourth backscatter detector 22D and the third backscatter detector 22C. The first backscatter detector 22A is located on the opposite side of the transmitted X-ray source 11 and is affected by the afterglow of the transmitted X-ray beam before or after attenuation, thus being the most affected. Therefore, the beams are emitted in turn in the order of the third backscattered beam source 21C, the fourth backscattered beam source 21D, the second backscattered beam source 21B, and the first backscattered beam source 21A. Compared with other beam emission sequences, this is beneficial to reduce the afterglow effect of the transmitted beams on the backscatter detectors at each viewing angle.

[0163] In this embodiment, the backscatter signal correction device 30 acquires an afterglow signal once every time the transmitted ray source 11 outputs a transmitted ray beam.

[0164] For any parts not described in the embodiment corresponding to Figure 10, please refer to the relevant descriptions in other embodiments.

[0165] Figure 11 is a schematic diagram of the arrangement of the transmission inspection device and the backscattering inspection device relative to the inspection channel of a radiation inspection system according to an embodiment of the present disclosure, wherein the radiation inspection system includes one transmission inspection device and three backscattering inspection devices. Figure 12 is a timing diagram of the transmission beam emitted by the transmission X-ray source 11 of the transmission inspection device of the radiation inspection system shown in Figure 11 and the pencil-shaped X-ray beam output by the backscattering X-ray source 21 of the backscattering inspection device 20.

[0166] As shown in Figure 11, the radiation inspection system includes one transmission inspection device and three backscatter inspection devices. The transmission X-ray source 11 of the transmission inspection device is located on the right side of the inspection channel P, and the transmission detector 12 is located on the left side of the inspection channel P. The three backscatter inspection devices are: a first backscatter inspection device 20A located above the transmission detector 12 on the left side of the inspection channel P (left-angle view), a second backscatter inspection device 20B located above the transmission X-ray source 11 on the right side of the inspection channel P (right-angle view), and a third backscatter inspection device 20C located above the inspection channel P (top-angle view).

[0167] The first backscattering inspection device 20A includes a first backscattering X-ray source 21A and a second backscattering detector 22A. The second backscattering inspection device 20B includes a second backscattering X-ray source 21B and a second backscattering detector 22B. The third backscattering inspection device 20C includes a third backscattering X-ray source 21C and a third backscattering detector 22C. The exit directions of the transmitted X-ray beam emitted by the transmitted X-ray source 11 and the pencil-shaped X-ray beam emitted by the backscattering X-ray sources of the backscattering inspection devices at each viewing angle are all directed towards the scanning channel P and perpendicular to the extension direction of the scanning channel P.

[0168] In Figure 12, the vertical lines qualitatively indicate the relative magnitude of the energy E of the transmitted X-ray beam output by the accelerator, and the shading qualitatively indicates the relative magnitude of the energy E of the pencil-shaped X-ray beam output by the backscattered X-ray sources at each viewing angle during the beam exit time period. Furthermore, in order to distinguish between the transmitted X-ray beam emitted by the transmitted X-ray source and the pencil-shaped X-ray beam emitted by the backscattered X-ray sources at each viewing angle, the transmitted X-ray beam is labeled "transmitted", the pencil-shaped X-ray beam emitted by the first backscattered X-ray source 21A is labeled "backscattered 1", the pencil-shaped X-ray beam emitted by the second backscattered X-ray source 21B is labeled "backscattered 2", and the pencil-shaped X-ray beam emitted by the third backscattered X-ray source 21C is labeled "backscattered 3".

[0169] As shown in Figure 12, in this embodiment, between every two pulses of the accelerator that serves as the transmission X-ray source 11, only the backscattered X-ray source of the backscattered inspection device at a certain angle emits a beam, and the backscattered X-ray sources at each angle emit beams in turn in the order of the first backscattered X-ray source 21A, the second backscattered X-ray source 21B, and the third backscattered X-ray source 21C.

[0170] For any parts not described in the embodiments corresponding to Figures 11 and 12, please refer to the relevant descriptions in other embodiments.

[0171] Figure 13 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20, which is an alternative embodiment of the radiation inspection system shown in Figures 11 and 12.

[0172] As shown in Figure 13, the difference between this embodiment and the radiation inspection system shown in Figures 11 and 12 lies in the different beam emission methods of the transmitted X-ray source and the backscattered X-ray source at each viewing angle.

[0173] In the embodiment shown in Figure 13, in order to reduce the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewing angle, the radiation scan of the backscatter inspection device at three viewing angles is completed between the pulses of the two transmitted X-ray beams, that is, within a time interval. The backscatter X-ray sources at each viewing angle are emitted in turn in the order of the first backscatter X-ray source 21A, the second backscatter X-ray source 21B, and the third backscatter X-ray source 21C.

[0174] For any parts not described in the embodiments corresponding to Figure 13, please refer to the relevant descriptions in other embodiments.

[0175] Figure 14 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20, which is an alternative embodiment of the radiation inspection system shown in Figures 11 and 12.

[0176] As shown in Figure 14, the difference between this embodiment and the radiation inspection system shown in Figures 11 and 12 lies in the different beam emission methods of the transmitted X-ray source and the backscattered X-ray source at each viewing angle.

[0177] In the embodiment shown in Figure 14, in order to reduce the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewing angle, the radiation scan of the backscatter inspection device at three viewing angles is completed between the pulses of the two transmitted X-ray beams, that is, within a time interval. The backscatter X-ray sources at each viewing angle are emitted in turn in the order of the third backscatter X-ray source 21C, the second backscatter X-ray source 21B, and the first backscatter X-ray source 21A.

[0178] In this embodiment, the third backscatter detector 22C is located above the transmitted X-ray source 11, and therefore experiences relatively less afterglow. The second backscatter detector 22B is located on the same side of the transmitted X-ray source 11 and is affected by the afterglow of the backscattered X-rays generated after the transmitted X-ray beam irradiates the object being inspected; the impact is greater than that on the third backscatter detector 22C. The first backscatter detector 22A is located on the opposite side of the transmitted X-ray source 11 and is affected by the afterglow of the transmitted X-ray beam before or after attenuation, thus experiencing the greatest impact. Therefore, emitting the beam in the order of the third backscatter source 21C, the second backscatter source 21B, and the first backscatter source 21A in turn reduces the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewing angle compared to other beam emission sequences.

[0179] For any parts not described in the embodiments corresponding to Figure 14, please refer to the relevant descriptions in other embodiments.

[0180] Figure 15 is a schematic diagram of the arrangement of the transmission inspection device and the backscattering inspection device relative to the inspection channel of a radiation inspection system according to an embodiment of the present disclosure, wherein the radiation inspection system includes one transmission inspection device and two backscattering inspection devices. Figure 16 is a timing diagram of the transmission beam emitted by the transmission X-ray source 11 of the transmission inspection device of the radiation inspection system shown in Figure 15 and the pencil-shaped X-ray beam output by the backscattering X-ray source 21 of the backscattering inspection device 20.

[0181] As shown in Figure 15, the radiation inspection system includes one transmission inspection device and two backscattering inspection devices. The transmission X-ray source 11 of the transmission inspection device is located on the right side of the inspection channel P, and the transmission detector 12 is located on the left side of the inspection channel P. The two backscattering inspection devices are a first backscattering inspection device 20A located above the transmission detector 12 on the left side of the inspection channel P (left-angle view) and a second backscattering inspection device 20B located above the transmission X-ray source 11 on the right side of the inspection channel P (right-angle view).

[0182] The first backscattering inspection device 20A includes a first backscattering X-ray source 21A and a second backscattering detector 22A. The second backscattering inspection device 20B includes a second backscattering X-ray source 21B and a second backscattering detector 22B. The exit directions of the transmitted X-ray beam emitted by the transmitted X-ray source 11 and the pencil-shaped X-ray beam emitted by the backscattering X-ray sources of the backscattering inspection devices at each viewing angle are all directed towards the scanning channel P and perpendicular to the extension direction of the scanning channel P.

[0183] In Figure 16, the vertical lines qualitatively indicate the relative magnitude of the energy E of the transmitted X-ray beam output by the accelerator, and the shading qualitatively indicates the relative magnitude of the energy E of the pencil-shaped X-ray beam output by the backscattered X-ray sources at each viewing angle during the beam-out time period. Furthermore, in order to distinguish between the transmitted X-ray beam emitted by the transmitted X-ray source and the pencil-shaped X-ray beam emitted by the backscattered X-ray sources at each viewing angle, the transmitted X-ray beam is labeled "transmission", the pencil-shaped X-ray beam emitted by the first backscattered X-ray source 21A is labeled "backscatter 1", and the pencil-shaped X-ray beam emitted by the second backscattered X-ray source 21B is labeled "backscatter 2".

[0184] As shown in Figure 16, in this embodiment, between every two pulses of the accelerator that serves as the transmission X-ray source 11, only the backscattered X-ray source of the backscattered inspection device at a certain angle emits a beam, and the backscattered X-ray sources at each angle emit beams in turn in the order of the first backscattered X-ray source 21A and the second backscattered X-ray source 21B.

[0185] For any parts not described in the embodiments corresponding to Figures 15 and 16, please refer to the relevant descriptions in other embodiments.

[0186] Figure 17 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20, an alternative embodiment of the radiation inspection system shown in Figures 15 and 16.

[0187] As shown in Figure 17, the difference between this embodiment and the radiation inspection system shown in Figures 15 and 16 lies in the different beam emission methods of the transmitted X-ray source and the backscattered X-ray source at each viewing angle.

[0188] In the embodiment shown in Figure 17, in order to reduce the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewpoint, the radiation scan of the backscatter inspection device at two viewpoints is completed between the pulses of the two transmitted X-ray beams, that is, within a time interval. The backscatter X-ray sources at each viewpoint are emitted in turn according to the order of the first backscatter X-ray source 21A and the second backscatter X-ray source 21B.

[0189] For any parts not described in the embodiments corresponding to Figure 17, please refer to the relevant descriptions in other embodiments.

[0190] Figure 18 is a timing diagram of the transmission beam emitted by the transmission beam source 11 of the transmission inspection device and the pencil beam output by the backscattering beam source 21 of the backscattering inspection device 20 in another alternative embodiment of the radiation inspection system shown in Figures 15 and 16.

[0191] As shown in Figure 18, the difference between this embodiment and the radiation inspection system shown in Figures 11 and 12 lies in the different beam emission methods of the transmitted X-ray source and the backscattered X-ray source at each viewing angle.

[0192] In the embodiment shown in Figure 18, in order to reduce the afterglow effect of the transmitted X-ray beam on the backscatter detectors at each viewpoint, the radiation scan of the backscatter inspection device at two viewpoints is completed between the pulses of the two transmitted X-ray beams, that is, within a time interval. The backscatter X-ray sources at each viewpoint are emitted in turn according to the order of the second backscatter X-ray source 21B and the first backscatter X-ray source 21A.

[0193] In this embodiment, the second backscatter detector 22B is located on the same side as the transmitted X-ray source 11 and is affected by the afterglow of the backscattered X-rays generated after the transmitted X-ray beam irradiates the object being inspected. The first backscatter detector 22A is located on the opposite side of the transmitted X-ray source 11 and is affected by the afterglow of the transmitted X-ray beam before or after attenuation, and is more affected than the second backscatter detector 22B. Therefore, by alternately emitting the beams in the order of the second backscatter source 21B and the first backscatter source 21A, compared to other beam emission orders, it is beneficial to reduce the afterglow effect of the transmitted X-ray beams on the backscatter detectors at each viewing angle.

[0194] For any parts not described in the embodiment corresponding to Figure 18, please refer to the relevant descriptions in other embodiments.

[0195] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit them; although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this disclosure or equivalent substitutions can be made to some technical features, all of which should be covered within the scope of the technical solutions claimed in this disclosure.

Claims

1. A radiation inspection system having an inspection channel (P) for an object to be inspected to pass through, comprising: The transmission inspection device (10) includes a transmission radiation source (11) and a transmission detector (12) disposed on opposite sides of the inspection channel (P), and is configured to perform transmission inspection on the object to be inspected passing through the inspection channel (P). and A backscattering inspection device (20) includes a backscattering X-ray source (21) and a backscattering detector (22) disposed on the same side of the inspection channel (P), and is configured to perform backscattering inspection on the object to be inspected passing through the inspection channel (P), wherein the time at which the transmission X-ray source (11) outputs the transmission X-ray beam is staggered from the time at which the backscattering X-ray source (21) outputs the pencil X-ray beam. A backscattering signal correction device (30) is connected to the backscattering detector (22) and is configured to subtract the afterglow signal generated by the transmitted ray beam output by the transmitted ray source (11) on the backscattering detector (22) from the backscattering detection signal generated by the backscattering detector (22) when the pencil ray beam is output to form a backscattering correction signal. and A backscatter image processing device (50) is signal-connected to the backscatter signal correction device (30) and configured to form a backscatter image based on the backscatter correction signal.

2. The radiation inspection system according to claim 1, wherein... The afterglow signal is formed based on pre-stored data in the backscatter signal correction device (30); or The afterglow signal is obtained on-site by the backscatter detector when the transmitted X-ray beam output stops and the pencil X-ray beam is not output during the operation of the radiation inspection system.

3. The radiation inspection system according to claim 2, wherein the backscatter signal correction device (30) acquires the afterglow signal multiple times on site and forms a backscatter correction signal based on the most recently acquired afterglow signal on site.

4. The radiation inspection system according to claim 3, wherein Each time the transmitted beam is output by the transmitted beam source (11), the backscatter signal correction device (30) acquires the afterglow signal on-site; or The flying point device (212) of the backscattered ray source (21) includes a fixed part (2121) and a movable part (2122) that moves periodically relative to the fixed part (2121). Each time the movable part (2122) moves for one cycle, the backscattered signal correction device (30) acquires the afterglow signal once on site.

5. The radiation inspection system according to any one of claims 2 to 4, wherein The transmitted ray source (11) outputs the transmitted ray beam in a pulsed manner; The backscattered ray source (21) outputs the pencil-shaped ray beam during the time interval between adjacent transmitted ray beams; The backscatter signal correction device (30) acquires the afterglow signal on-site based on the backscatter detection signal of the backscatter detector (22) during the silent period when it stops outputting the pencil-shaped beam, excluding the interval time between adjacent transmitted beams.

6. The radiation inspection system according to claim 5, wherein the backscattered beam source (21) comprises a radiation source (211) and a flying point device (212), the flying point device (212) comprising a fixed part (2121) fixedly disposed relative to the radiation source (211) and a movable part (2122) periodically moving relative to the fixed part (2121), the flying point device (212) being configured to output or stop outputting the pencil beam by the relative movement of the fixed part (2121) and the movable part (2122).

7. The radiation inspection system according to claim 5 or 6, wherein the backscatter signal correction device (30) fits the afterglow attenuation curve based on the backscatter detection signal of the backscatter detector (22) during the silent period, and forms the afterglow signal based on the afterglow attenuation curve.

8. The radiation inspection system of claim 7, wherein the afterglow decay curve is I = I0e t - a -t / τ wherein, t is the fitting time; It represents the afterglow signal at the fitting time t; I0 is the backscattered detection signal at the fitting time t is zero; τ is the decay time constant of the backscatter detector (22).

9. The radiation inspection system according to any one of claims 1 to 8, wherein the transmission inspection device (10) and the backscattering inspection device (20) are configured such that the transmitted beam and the pencil beam are coplanar.

10. The radiation inspection system according to any one of claims 1 to 9, wherein the radiation inspection system comprises two or more backscattering inspection devices (20) with different viewing angles and / or two or more transmission inspection devices (10) with different viewing angles.

11. The radiation inspection system according to any one of claims 1 to 10, wherein a pencil beam is output once or multiple pencil beams are output within the time interval of each adjacent transmitted beam.

12. The radiation inspection system of claim 11, wherein multiple pencil beams are output within the time interval of each adjacent transmitted beam, wherein the output order of the multiple pencil beams is sorted from least to most affected by the afterglow signal of the transmitted beams on the backscatter detector (22) receiving the pencil beams.

13. The radiation inspection system according to any one of claims 1 to 12, wherein the backscatter detector (22) comprises a plastic scintillator or a GAGG crystal.

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