CN109343135B - Multi-level energy type static security check CT system and imaging method - Google Patents
Multi-level energy type static security check CT system and imaging method Download PDFInfo
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Abstract
The invention discloses a multi-level energy type static security check CT system and an imaging method. The static security inspection CT system comprises at least one group of N-level image chain structures, wherein a luggage conveying belt is arranged on the inner side of the bottom of each N-level image chain structure, and the N-level image chain structures and the luggage conveying belt are fixed at preset positions of the static security inspection CT system through a rack; each group of N-level image chain structures are sequentially arranged in the advancing direction of the luggage channel, and the adjacent groups of N-level image chain structures are arranged in a staggered mode. The static security check CT system can generate images with higher time resolution and more energy spectrum levels than spiral CT through the exposure of different time sequence ray sources in the N-level image chain structure, and can improve the identification rate of contraband in the luggage and the luggage check speed. On the other hand, the static security check CT system gets rid of dependence on a slip ring, and the multi-focus X-ray source and the detector do not need to rotate, so that non-rotation static imaging is realized.
Description
Technical Field
The invention relates to a multi-level energy type static security check CT system (hereinafter referred to as a static security check CT system), and also relates to an imaging method of the multi-level energy type static security check CT system, belonging to the technical field of radiation imaging.
Background
With the further improvement of the requirement on the precision of the security inspection technology at home and abroad, the traditional perspective security inspection equipment tends to be gradually replaced by CT equipment in important places such as civil aviation, customs and the like; in addition, the requirement on the precision of the security inspection technology is improved, and meanwhile, the detection speed of the security inspection technology is also higher.
The existing security check CT equipment is divided into two types, one type is spiral CT equipment based on a slip ring technology. Among this spiral CT equipment, ray source and detector need be rotatory around the testee, and the highest rotational speed of security check CT can reach about 4 rings per second at present, and each part need bear huge centrifugal force among the rotatory process, and this has proposed higher requirement to the design of key part, especially to the security check CT of large aperture, because the angle of view of scanning is bigger, and the distance of rotation center to key part can be bigger, and under the equal rotational speed, the centrifugal force that key part need bear will be bigger. Meanwhile, after the rotation speed of the spiral CT equipment is increased, the reliability, the safety, the stability and the service life of the whole spiral CT equipment are influenced to a certain degree. Therefore, the rotation speed is difficult to be increased to a certain degree, and in practical application, the requirement of security inspection on the inspection speed is higher and higher. In addition, a slip ring is generally used in the spiral security inspection CT for power supply and data and control signal transmission, and the service life of a carbon brush used for data transmission and power supply in a slip ring system is short, so that the maintenance cost is increased and the maintenance period is shortened; moreover, the noise of the transmission device driving the radiation source and the detector to rotate can also bring about poor user experience.
The other is a static CT device. The static CT device is not provided with a slip ring, and the ray source and the detector do not have rotary motion relative to the detected object. In addition, compared with the spiral CT apparatus, the static CT apparatus has the characteristics of fast inspection speed, low maintenance cost, high reliability, and the like, and is emphasized in the field of security inspection in recent years. However, the existing static CT technology is difficult to meet various requirements such as dual-energy imaging, imaging quality, and scatter suppression, and still has significant disadvantages.
Disclosure of Invention
The invention aims to provide a multi-level energy type static security check CT system.
Another technical problem to be solved by the present invention is to provide an imaging method for a multi-level energy type static security CT system.
In order to achieve the purpose, the invention adopts the following technical scheme:
according to a first aspect of the embodiments of the present invention, there is provided a multi-level energy type static security check CT system, including at least one set of N-level image chain structures, a baggage conveyor belt is disposed at an inner side of a bottom of each of the N-level image chain structures, and the N-level image chain structures and the baggage conveyor belt are fixed at preset positions of the static security check CT system through a rack, where N is a positive integer;
each group of the N-level image chain structures are sequentially arranged in the advancing direction of the luggage channel, and the adjacent groups of the N-level image chain structures are arranged in a staggered mode.
Preferably, each of the N-level image chain structures is composed of N single-level image chain units;
each single-stage image chain unit in each group of N-stage image chain structures is sequentially arranged in the advancing direction of the baggage passage, and the adjacent single-stage image chain units are arranged in a staggered manner.
Preferably, each single-stage image chain unit comprises a multi-focus X-ray source and a detector assembly; among a plurality of focuses formed by the multi-focus X-ray source, adjacent focuses are arranged in a straight line mode at equal intervals, in an equal-angle circular arc mode or in an equal-angle curve mode.
Preferably, for the same single-stage image chain unit, in the multiple focuses formed by the multiple focus X-ray sources, an included angle formed between a connecting line from the two focuses located at the outermost side to the virtual rotation center and a connecting line from the focus located at the middle position to the virtual rotation center is not more than 5 °, and an included angle formed between a connecting line from the two focuses located at the outermost side to the virtual rotation center is not more than 10 °.
Preferably, in the plurality of focuses formed by the multi-focus X-ray source, the fan angle of the spread of the ray bundle corresponding to each focus covers the edge of the luggage channel; and the equivalent rotation angle formed by the multi-focus X-ray source and the detector assembly of each single-stage image chain unit is not lower than 180 degrees + max (theta1, theta2, theta3, … and theta M), wherein max (theta1, theta2, theta3, … and theta M) is the largest fan angle selected from fan angles of opening of ray bundles corresponding to a plurality of focuses formed by the multi-focus X-ray source.
Preferably, the multi-level energy type static security inspection CT system further comprises a gate switch for controlling emission/stop of emission of each ray tube or ray source of each single-level image chain unit.
Preferably, the detector assembly comprises an arc detector support and a plurality of detectors, the plurality of detectors are arranged on the arc detector support with the center of the luggage channel as the center of a circle, and the plurality of detectors are opposite to the middle positions of the plurality of focuses of the multi-focus X-ray source.
Preferably, the detector is any one or combination of a plurality of single-energy detectors, dual-energy sandwich detectors and photon counting detectors.
Preferably, when the detector is the single-row detector, the single-row detector and the focal point of the multi-focus X-ray source share an XY plane, and the single-row detector faces to the middle position of the multiple focal points of the multi-focus X-ray source;
when the detector is the multi-row detector, a middle row of the multi-row detector and the multiple focuses of the multi-focus X-ray source share an XY plane, and the multi-row detector faces to the middle position of the multiple focuses of the multi-focus X-ray source.
According to a second aspect of the embodiments of the present invention, there is provided an imaging method implemented by the above-mentioned multi-level energy type static security check CT system, including the steps of:
the method comprises the following steps that luggage or packages enter a luggage channel, focal points in a multi-focal-point X-ray source of each single-stage image chain unit are controlled to be sequentially exposed according to a preset time sequence, and projection data of the luggage or the packages passing through each single-stage image chain unit are collected through corresponding detector components;
when the luggage or the package reaches the last single-level image chain unit of each group of N-level image chain structures, sequentially reconstructing and identifying each tomographic image from the first tomographic image of the luggage or the package;
when the luggage or the package leaves the last single-stage image chain unit of each group of the N-stage image chain structures, the acquisition of projection data is completed, and the reconstruction and the identification of the rest fault images are continuously and sequentially carried out;
and after the reconstruction and the identification of each tomography image of the whole luggage or the parcel are completed, giving alarm information so as to complete the complete detection of one luggage or parcel.
On one hand, the multi-level energy type static security inspection CT system provided by the invention adopts a plurality of single-level image chain units consisting of multi-focus X-ray sources and detector components to form an N-level image chain structure. By exposing the ray sources with different time sequences in the N-level image chain structure, images with higher time resolution and more energy spectrum levels than those of spiral CT can be generated, and the identification rate of contraband in the luggage and the luggage inspection speed are improved. On the other hand, the static security check CT system gets rid of dependence on a slip ring, and the multi-focus X-ray source and the detector do not need to rotate, so that non-rotation static imaging is realized. Meanwhile, the static security inspection CT system is not provided with a rotating part, so that the maintenance cost and the noise of the equipment are reduced, and the stability of the equipment is improved.
Drawings
FIG. 1 is a cross-sectional view of a static security CT system according to the present invention;
FIG. 2 is a diagram of an internal structure of a static security CT system according to the present invention;
FIG. 3 is a structural diagram of an N-level image chain structure in the static security inspection CT system according to the present invention;
FIG. 4 is a schematic diagram of an optical path of an adjacent single-stage image chain unit in the static security inspection CT system provided in the present invention;
FIG. 5 is a schematic diagram of an optical path of a single-stage image chain unit in the static security inspection CT system according to the present invention;
FIG. 6 is a block diagram of a single row of detectors in the static security CT system of the present invention;
FIG. 7 is a block diagram of a multi-row detector in a static security CT system according to the present invention;
FIG. 8 is a flowchart of an imaging method of the static security check CT system according to the present invention.
Detailed Description
The technical contents of the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1 and fig. 2, the multi-level energy type static security inspection CT system provided by the present invention includes a housing 1, a shielding curtain 2 at a cargo inlet, and a shielding curtain 7 at a cargo outlet, wherein at least one group of N-level image chain structures 5 is disposed inside the housing 1, a baggage conveyor belt 4 is disposed on an inner side of a bottom of the N-level image chain structure 5, and the N-level image chain structures 5 and the baggage conveyor belt 4 are fixed at predetermined positions of the static security inspection CT system by a frame 8, so that the baggage conveyor belt 4 transports a baggage or a package 3 to be inspected to the N-level image chain structures 5, and the N-level image chain structures 5 complete the acquisition of projection data, and transmit the acquired projection data to a computer to generate a three-dimensional tomographic image of the baggage or package 3 to be inspected.
Wherein each group of N-level image chain structure 5 is composed of N single-level image chain units, and the range of N is preferably 10-30. For example, assuming that each set of N-level image chain structure 5 in the static security inspection CT system is a 5-level image chain structure composed of 5 single-level image chain units, as shown in fig. 3, the 5-level image chain structure includes a single-level image chain unit 5-1, a single-level image chain unit 5-2, a single-level image chain unit 5-3, a single-level image chain unit 5-4, and a single-level image chain unit 5-5, respectively.
As shown in fig. 4, in order to achieve multiple scanning viewing angle requirements of different baggage or packages, the single-stage image chain units in each group of N-stage image chain structures 5 are sequentially arranged in the advancing direction of the baggage passageway, and adjacent single-stage image chain units may be arranged at the same or different angles, i.e., adjacent single-stage image chain units need to be staggered by a certain angle θ (e.g., the angle θ between the single-stage image chain unit 5-1 and the single-stage image chain unit 5-2). For example, in each set of N-level image chain structures 5, the first single-level image chain unit is arranged at 0 °, the second single-level image chain unit is circumferentially shifted from the first single-level image chain unit by an angle θ, the third single-level image chain unit is circumferentially shifted from the second single-level image chain unit by an angle θ, and so on … …. The angle theta staggered between adjacent single-level image chain units and the number of the single-level image chain units of each group of N-level image chain structures are selected and need to be adjusted according to actual imaging requirements. For example, the angle θ of the shift between the adjacent single-level image chain units in each group of N-level image chain structures and the number of single-level image chain units are adjusted according to the projection range (angle of the rotation around the object) of the single-level image chain units of each group of N-level image chain structures 5 forming a certain angle around the object.
Similarly, in order to meet the requirement of multiple imaging angles of different baggage or packages, the N-level image chain structures 5 of each group are sequentially arranged in the advancing direction of the baggage passage, and the N-level image chain structures 5 of adjacent groups may be staggered at the same or different angles, i.e. the N-level image chain structures 5 of adjacent groups need to be staggered at a certain angle. The angle of the stagger between the adjacent sets of N-level image chain structures 5 and the number of sets of N-level image chain structures need to be adjusted according to the actual imaging requirement.
As shown in fig. 5, each single-stage image train unit includes a multi-focus X-ray source 9 and a detector assembly 10. The multi-focus X-ray source 9 can be packaged into an integral source by M ray tubes, and the range of M is preferably 2-24; the multi-focus X-ray source 9 may also be assembled as an assembly from a plurality of small ray sources. Among a plurality of focuses formed by the multi-focus X-ray source 9, adjacent focuses may be arranged in a straight line with equal spacing, or in an arc or curve with equal angle.
Specifically, since a virtual rotation center exists between the single-stage image chain units of each group of N-stage image chain structures 5 in the XY plane, the coordinate of the virtual rotation center in the XY plane is (0, 0), and the virtual rotation center coordinate of each single-stage image chain unit is the same, i.e., the rotation center is shared. The coordinate of the virtual rotation center in the XY plane is (0, 0) which is the center coordinate of the arc structure enclosed by the single-stage image chain units of each group of N-stage image chain structures 5. As shown in fig. 1 and 2, the XY plane refers to a direction parallel to the width direction of the baggage conveyor 4 as an X axis, a direction perpendicular to the surface of the baggage conveyor 4 upward as a Y axis, and a length direction of the baggage conveyor 4 as a Z axis; the plane formed by the X axis and the Y axis is the XY plane.
In order to ensure that the imaging field of view (FOV) of the static security check CT system is large enough, so that multiple focuses of the multi-focus X-ray source 9 of each single-stage image chain unit can share the same detector component, and further ensure that when the static security check CT system realizes dual-energy imaging, pixels of the dual-energy interlayer detector can be aligned, as described later, pixels of the low-energy detector of the high-energy detector are aligned, so that the imaging data of each pixel of the low-energy detector corresponds to the imaging data of each pixel of the high-energy detector one-to-one, for the same single-stage image chain unit, in the multi-focus formed by the multi-focus X-ray source 9, the included angle formed by the connecting line of the two focuses at the outermost side to the virtual rotation center and the connecting line of the focus at the middle position to the virtual rotation center is not more than 5 degrees respectively, and the angle formed by the connecting lines of the two focus points positioned at the outermost side to the virtual rotation center is not more than 10 degrees.
In the multiple focuses formed by the multi-focus X-ray source 9, because the positions of the ray tubes or ray sources (small ray sources) corresponding to different focuses are different, the fan angles of the spread of the ray beams corresponding to different focuses may be different, and may respectively represent theta1, theta2, theta3, and … … theta m. Wherein the opened fan angle of the ray beam corresponding to each focus covers the edge of the luggage channel, so as to ensure that the X-ray beam emitted by the ray tube or the ray source (small ray source) corresponding to each focus can completely cover the checked luggage or the package. In addition, in each group of N-level image chain structures 5, the multi-focus X-ray source 9 and the detector assembly 10 of each single-level image chain unit form a projection range of a certain angle of rotation around the object, and in order to ensure that when the multi-focus X-ray source 9 emits a ray bundle, the corresponding detector assembly will receive projection data of equivalent rotation around the object, the equivalent rotation angle formed by the multi-focus X-ray source 9 and the detector assembly 10 of each single-level image chain unit is not less than 180 ° + max (theta1, theta2, theta3, …, theta m), so that the equivalent rotation angle formed by the multi-focus X-ray source 9 and the detector assembly satisfies the data range of half scanning; max (theta1, theta2, theta3, …, theta M) is the largest fan angle selected among fan angles of beam spread corresponding to the multiple focal points formed by the multi-focal point X-ray source 9.
The static security inspection CT system is further provided with a gate switch for controlling each ray tube or ray source (small ray source) of the single-stage image chain unit in each group of N-stage image chain structures 5 to rapidly emit/stop emitting X-ray beams. According to the running speed of the luggage conveyer belt 4 of the static security check CT system, the row number of each detector component in each group of N-level image chain structures 5 and the response time of the detector components, the exposure sequence and the exposure dose of different focuses (such as the focuses 9-1 to 9-3) of the multi-focus X-ray source 9 are controlled.
As shown in fig. 5, the detector assembly 10 includes a circular arc detector support 13 and a plurality of detectors 11, the plurality of detectors 11 are disposed on the circular arc detector support 13 centered (at a center 12) about the center of the baggage aisle, and the plurality of detectors are aligned with the center of the plurality of focal points of the multi-focal spot X-ray source. The multi-focal spot X-ray scanning area formed between the detectors (detector 11-1 and detector 11-N) should be large enough to cover the entire baggage aisle 15 being examined.
In the detector assembly 10, the detector 11 may be any one or a combination of multiple kinds of a single-energy detector, a dual-energy sandwich detector, and a photon counting detector. For example, it is assumed that the detector employs a dual-energy sandwich detector, which is a high-low energy detector; as shown in fig. 6, each of the high and low energy detectors is composed of a low energy detector 111 located at an upper layer and a high energy detector 112 located at a lower layer; when the to-be-inspected luggage or package 3 sequentially passes through each single-level image chain unit of a certain group of N-level image chain structures from a cargo inlet through a luggage conveying belt 4, each single-level image chain unit can emit fan-shaped X-ray beams according to time sequence from a multi-focus X-ray source 9, a high-low energy detector of a detector assembly 10 corresponding to each single-level image chain unit can receive the X-ray beams attenuated by the cargo, the X-ray beams contain low-energy and high-energy X-ray spectrums, the low-energy and high-energy detectors in the detector assembly 10 respectively receive corresponding X-ray signal data and transmit the data to a background computer, each to-be-inspected luggage or package can obtain the data acquired from the N-level image chain structures, and the data are processed through a certain algorithm to generate three-dimensional tomographic images of the luggage or package.
The detectors in the detector assembly 10 may be single or multiple row detectors, depending on the imaging range requirements. As shown in fig. 6, when the imaging range is small, a single row of detectors may be selected, in which case, the single row of detectors and the focal point of the multi-focus X-ray source share an XY plane, and the single row of detectors is directly opposite to the middle position of the multiple focal points of the multi-focus X-ray source. As shown in fig. 7, when the imaging range is large, multiple rows of detectors may be selected, in which case, the middle row of detectors in the multiple rows of detectors and multiple focuses of the multi-focus X-ray source share an XY plane, and the multiple rows of detectors face the middle positions of the multiple focuses of the multi-focus X-ray source.
As shown in fig. 2, the static security check CT system further includes a high voltage generator 6 for providing a high voltage to each of the multi-focus X-ray sources. When the detector in the detector assembly 10 is a single-energy detector, the working voltage of each multi-focus X-ray source can be different, and the high voltage emitted by the high-voltage generator 6 is controlled, so that each multi-focus X-ray source is at different working voltages, and further the static security check CT system can complete dual-energy imaging, three-energy imaging or multi-energy imaging. In addition, the detector can adopt a dual-energy interlayer detector to realize that the static security check CT system completes dual-energy imaging, for example, the high-low energy detector adopts the same voltage value to realize that the static security check CT system completes dual-energy imaging; or, the detector component adopts a photon counting detector to realize that the static security check CT system completes multi-energy imaging.
The structure of the multi-level energy type static security inspection CT system provided by the present invention is described above, and the imaging method of the multi-level energy type static security inspection CT system provided by the present invention is described in detail below.
As shown in fig. 8, the imaging method of the multi-level energy type static security check CT system provided by the present invention includes the following steps:
step S1: and (3) enabling the luggage or the package to enter a luggage channel, controlling the focuses in the multi-focus X-ray sources of the single-stage image chain units to be sequentially exposed according to a preset time sequence, and acquiring projection data when the package passes through the single-stage image chain units through the corresponding detector assembly.
When luggage or packages pass through each single-stage image chain unit of a certain group of N-stage image chain structures from a goods inlet through the luggage conveying belt 4 in sequence, the exposure sequence of focuses in the multi-focus X-ray sources of each single-stage image chain unit in each group of N-stage image chain structures 5 and the size of exposure dose are controlled through a grid control switch according to the running speed of the luggage conveying belt 4 of the static security check CT system, the row number of each detector component in each group of N-stage image chain structures 5 and the response time of each detector component.
Because only one ray tube or ray source can emit ray beams at a time, one ray tube or ray source in the multi-focus X-ray source of each single-stage image chain unit can be controlled at a time to emit ray beams through the grid control switch according to the exposure sequence of the focus in the multi-focus X-ray source of each single-stage image chain unit. Therefore, the focuses in the multi-focus X-ray sources of the single-stage image chain units can be controlled to be sequentially exposed through the grid control switch, the focus in the multi-focus X-ray source of each single-stage image chain unit is projected onto the corresponding detector assembly after being exposed, and therefore projection data when luggage or packages pass through the single-stage image chain units are collected through the corresponding detector assembly. Projection data acquired by the detector assembly of each single-stage image chain unit can be transmitted to a background computer.
Step S2: when the luggage or the package reaches the last single-level image chain unit of each group of N-level image chain structures, the reconstruction and the identification are sequentially carried out on the tomography images from the first tomography image of the luggage or the package.
Because the three-dimensional tomographic image of one baggage or parcel is composed of a plurality of tomographic images, and in the three-dimensional tomographic image of each baggage or parcel, the tomographic position corresponding to each baggage or parcel sequentially passes through all the single-level image chain units of the current group of N-level image chain structures, the projection data of the tomographic position acquired by each single-level image chain unit is reconstructed, and the tomographic image corresponding to the tomographic position is formed.
When the luggage or the package reaches the last single-stage image chain unit of each group of N-stage image chain structures, the single-stage image chain units of the current group of N-stage image chain structures finish the acquisition of projection data of the fault position of the head of the luggage or the package, so that the reconstruction of a first tomographic image corresponding to the fault position of the head of the luggage or the package can be realized according to the acquired projection data, and the reconstructed first tomographic image is identified through an identification program (for example, an image identification program commonly used in the existing security inspection CT) which is pre-installed by a computer according to the attenuation coefficient, the electron density and the equivalent atomic number of the first tomographic image so as to judge whether forbidden articles exist in the tomographic image. And (3) along with the travelling of the luggage or the package, sequentially passing through the last single-stage image chain unit of each group of N-stage image chain structures at a plurality of fault positions of the luggage or the package, and sequentially reconstructing and identifying other fault images of the luggage or the package by adopting a reconstruction and identification method of the first fault image.
It is emphasized that the background computer may employ an analytical reconstruction algorithm or an iterative reconstruction algorithm to reconstruct each tomographic image of the baggage or parcel; the background computer can also reconstruct each tomographic image of the baggage or parcel using a hybrid analytical and iterative reconstruction algorithm. When the product of the number of single-stage image chain units of each group of N-stage image chain structures and the number of focuses of the multi-focus ray source of each single-stage image chain unit is large, if the product is larger than 720, preferably reconstructing each tomographic image of the luggage or the parcel by adopting an analytic reconstruction algorithm; the implementation process of the analytical reconstruction algorithm can be found in the papers of Lenbang et al, "optimization iteration method for X-ray dual-energy computed tomography projection decomposition" (published in optics journal, 2017, 10: 365-.
When the product of the number of the single-stage image chain units of each group of N-stage image chain structures and the number of the focal points of the multi-focus ray source of each single-stage image chain unit is small, if the product is less than 360 degrees, each tomographic image of the luggage or the package is preferably reconstructed by adopting an iterative reconstruction algorithm. For the implementation of the Iterative Reconstruction algorithm, see Ruoqiao Zhang et al, "Model-Based Iterative Reconstruction for Dual-Energy X-Ray CT Using a Joint Quadrative Likeliod Model" (published in IEEE Transactions on medical imaging, 2014, 33: 117-) -134.
When the product of the number of single-stage image chain units of each group of N-stage image chain structures and the number of focuses of the multi-focus ray sources of each single-stage image chain unit is between 360 and 720, preferably adopting an analytic and iterative mixed reconstruction algorithm to reconstruct each tomographic image of the luggage or the package; for the implementation of the analytical and iterative hybrid reconstruction algorithm, see the article "Accurate iterative FBP reconstruction method for real energy CT" by Mengfei Li et al (published in IEEE Transactions on medical imaging, 2018).
Step S3: and when the luggage or the package leaves the last single-stage image chain unit of each group of N-stage image chain structures, completing the acquisition of projection data, and continuously and sequentially reconstructing and identifying the rest tomograms.
And when the luggage or the package leaves the last single-stage image chain unit of each group of N-stage image chain structures, finishing the acquisition of the projection data of the luggage or the package by the current group of N-stage image chain structures, and continuously reconstructing and identifying the rest tomograms which are not reconstructed and identified in the current luggage or the package by adopting the method of the step S2.
Step S4: and after reconstruction and identification of each tomographic image of the whole luggage or the package are completed, alarm information is given so as to complete detection of one package or the package.
After reconstruction and identification of each tomographic image of the luggage or the package are completed, if the luggage or the package is identified to possibly contain forbidden articles, alarm information is given, so that security personnel can conveniently carry out subsequent unpacking inspection work.
On one hand, the multi-level energy type static security inspection CT system provided by the invention adopts a plurality of single-level image chain units consisting of multi-focus X-ray sources and detector components to form an N-level image chain structure. By exposing the ray sources with different time sequences in the N-level image chain structure, images with higher time resolution and more energy spectrum levels than those of spiral CT can be generated, and the identification rate of contraband in the luggage and the luggage inspection speed are improved. On the other hand, the static security check CT system gets rid of dependence on a slip ring, and the multi-focus X-ray source and the detector do not need to rotate, so that non-rotation static imaging is realized. Meanwhile, the static security inspection CT system is not provided with a rotating part, so that the maintenance cost and the noise of the equipment are reduced, and the stability of the equipment is improved.
The multi-level energy type static security inspection CT system and the imaging method provided by the invention are explained in detail above. It will be apparent to those skilled in the art that any obvious modifications thereto can be made without departing from the true spirit of the invention, which is to be accorded the full scope of the claims herein.
Claims (9)
1. A multi-level energy type static security check CT system is characterized by comprising at least one group of N-level image chain structures, wherein a luggage conveying belt is arranged on the inner side of the bottom of each N-level image chain structure, the N-level image chain structures and the luggage conveying belt are fixed on preset positions of the static security check CT system through a rack, and N is a positive integer;
each group of the N-level image chain structures are sequentially arranged in the advancing direction of the luggage channel, and the adjacent groups of the N-level image chain structures are arranged in a staggered manner;
each group of the N-level image chain structure consists of N single-level image chain units;
each single-stage image chain unit in each group of N-stage image chain structures is sequentially arranged in the advancing direction of the baggage passage, and adjacent single-stage image chain units are staggered and arranged at the same or different angles along the circumferential direction.
2. The multi-level energy type static security CT system of claim 1, wherein:
each single-stage image chain unit comprises a multi-focus X-ray source and a detector assembly; among a plurality of focuses formed by the multi-focus X-ray source, adjacent focuses are arranged in a straight line mode at equal intervals, in an equal-angle circular arc mode or in an equal-angle curve mode.
3. The multi-level energy type static security CT system of claim 2, wherein:
for the same single-stage image chain unit, in the multiple focuses formed by the multiple focus X-ray source, an included angle formed between a connecting line from two focuses located on the outermost side to the virtual rotation center and a connecting line from a focus located in the middle to the virtual rotation center is not more than 5 degrees, and an included angle formed between a connecting line from two focuses located on the outermost side to the virtual rotation center is not more than 10 degrees.
4. The multi-level energy type static security CT system of claim 3, wherein:
in a plurality of focuses formed by the multi-focus X-ray source, the opened fan angle of the ray bundle corresponding to each focus covers the edge of the luggage channel; and the equivalent rotation angle formed by the multi-focus X-ray source and the detector assembly of each single-stage image chain unit is not lower than 180 degrees + max (theta1, theta2, theta3, … and theta M), wherein max (theta1, theta2, theta3, … and theta M) is the largest fan angle selected from fan angles of opening of ray bundles corresponding to a plurality of focuses formed by the multi-focus X-ray source.
5. The multi-level energy type static security CT system of claim 1, wherein:
and the multi-level energy type static security inspection CT system is also provided with a grid control switch for controlling the emission/stop of the emission of the ray tube or the ray source of each single-level image chain unit.
6. The multi-level energy type static security CT system of claim 2, wherein:
the detector assembly comprises an arc detector support and a plurality of detectors, the detectors are arranged on the arc detector support with the center of the luggage channel as the center of a circle, and the detectors are opposite to the middle positions of the focuses of the multi-focus X-ray source.
7. The multi-level energy type static security CT system of claim 6, wherein:
the detector is any one or combination of a plurality of single-energy detectors, double-energy interlayer detectors and photon counting detectors.
8. The multi-level energy type static security CT system of claim 7, wherein:
when the detector is the single-row detector, the single-row detector and the focal point of the multi-focus X-ray source share an XY plane, and the single-row detector is opposite to the middle position of the multiple focal points of the multi-focus X-ray source;
when the detector is the multi-row detector, a middle row of the multi-row detector and the multiple focuses of the multi-focus X-ray source share an XY plane, and the multi-row detector faces to the middle position of the multiple focuses of the multi-focus X-ray source.
9. An imaging method implemented by the multi-level energy type static security inspection CT system of any one of claims 1 to 8, characterized by comprising the steps of:
the method comprises the following steps that luggage or packages enter a luggage channel, focal points in a multi-focal-point X-ray source of each single-stage image chain unit are controlled to be sequentially exposed according to a preset time sequence, and projection data of the luggage or the packages passing through each single-stage image chain unit are collected through corresponding detector components;
when the luggage or the package reaches the last single-level image chain unit of each group of N-level image chain structures, sequentially reconstructing and identifying each tomographic image from the first tomographic image of the luggage or the package;
when the luggage or the package leaves the last single-stage image chain unit of each group of the N-stage image chain structures, the acquisition of projection data is completed, and the reconstruction and the identification of the rest fault images are continuously and sequentially carried out;
and after the reconstruction and the identification of each tomography image of the whole luggage or the parcel are completed, giving alarm information so as to complete the complete detection of one luggage or parcel.
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| PCT/CN2019/077239 WO2020087825A1 (en) | 2018-10-31 | 2019-03-06 | Multi-energy static security ct system and imaging method |
| AU2019373486A AU2019373486A1 (en) | 2018-10-31 | 2019-03-06 | Multi-energy static security ct system and imaging method |
| EP19879454.7A EP3872535A4 (en) | 2018-10-31 | 2019-03-06 | Multi-energy static security ct system and imaging method |
| JP2021523592A JP7352304B2 (en) | 2018-10-31 | 2019-03-06 | Multi-stage fixed safety inspection CT system and image forming method |
| US17/302,320 US11789175B2 (en) | 2018-10-31 | 2021-04-30 | Multi-energy static security CT system and imaging method |
| AU2023204307A AU2023204307A1 (en) | 2018-10-31 | 2023-07-04 | Multi-energy static security ct system and imaging method |
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| CN110495901A (en) * | 2019-09-12 | 2019-11-26 | 北京纳米维景科技有限公司 | The real-time CT imaging system of static state and image formation control method with pairs of radiographic source ring |
| CN111447373B (en) * | 2020-04-16 | 2021-10-26 | 北京纳米维景科技有限公司 | Automatic exposure control system and image correction method |
| CN112683934A (en) * | 2020-12-04 | 2021-04-20 | 重庆大学 | X-ray source static CT imaging system and method based on electron beam scanning |
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