Nine-source CT multi-energy level electron beam offset imaging method and imaging system

Abstract

The application discloses a kind of multi-energy level electron beam offset imaging method and imaging system of nine-source CT, belong to computer tomography field.The method includes: in 0 ° to 90 ° limited angle range, nine pairs of ray source-detector are arranged, corresponding nine continuous 10 ° angle interval respectively;Each pair is locally scanned by electron beam offset, and three ray energy levels are staggered collected according to preset energy level-angle correspondence, and mixed energy level limited angle projection data are obtained;After pre-processing, input diffusion model, and map into the 90 ° limited angle projection data corresponding to each energy level;Then respectively sent into the limited angle reconstruction model based on diffusion prior and data consistency constraint and iteratively reconstructed, and the reconstruction image of three energy levels is output.The application does not need mechanical rotation, and acquisition efficiency is high, can effectively separate multi-energy level information and inhibit limited angle artifact, and is suitable for material identification, defect detection and security check and the like scene.

Description

Technical Field

[0001] This invention relates to the field of computed tomography imaging technology, and in particular to a multi-level electron beam shift imaging method and imaging system for nine-source CT. Background Technology

[0002] The basic principle of CT imaging is to obtain projections of the examined object from multiple angles and then reconstruct the object's internal structure based on these projections. Generally speaking, the more complete the projection angles, the more stable the reconstruction result, the fewer artifacts in the image, and the easier it is to recover details.

[0003] However, in many real-world scenarios, the system cannot achieve full-angle scanning. For example, the equipment structure may only allow the X-ray to operate within a limited angular range; the object to be inspected may not be able to rotate freely; industrial inspection and security checks often require faster cycle times and more stable mechanical structures. In such cases, the system can only acquire limited angular data. The information in limited angular data is inherently incomplete, thus easily leading to problems such as trailing, stretching, edge blurring, structural gaps, and grayscale distortion in the reconstruction results.

[0004] On the other hand, multi-level imaging has significant advantages in materials analysis and target identification. Because the attenuation response of an object to radiation differs at different energy levels, multi-level data often provides richer information than single-level data. However, traditional multi-level imaging methods typically require a separate scan for each energy level, which leads to the following problems: 1. The data collection time has increased significantly; 2. Mechanical switching or system control is more complex; 3. Each energy level needs to be reconstructed separately, resulting in a greater computational burden; 4. Under finite angle conditions, the data for each energy level itself is still incomplete, making reconstruction more difficult.

[0005] While existing technologies include some finite angle reconstruction methods and some multi-level imaging methods, there is still a lack of a solution with a clear structure, a coherent process, and suitable for engineering implementation for the overall scheme of "nine pairs of fixed arrangement of X-ray source-detector array, electron beam deflection local scanning, three energy levels staggered acquisition, mixed energy level data splitting, and energy level finite angle reconstruction".

[0006] Therefore, a new approach is needed to complete 90° finite angle acquisition using nine pairs of arrayed X-ray sources and detectors without relying on mechanical rotation scanning. Then, the mixed energy level data is first decomposed into 90° finite angle data of three target energy levels using a depth model, and finally high-quality reconstruction is performed separately, thereby achieving a better balance between acquisition efficiency and imaging quality. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multi-level electron beam shift imaging method and system for nine-source CT. This method divides a finite angular range from 0° to 90° into nine consecutive 10° angular intervals, and correspondingly sets up nine pairs of X-ray source-detectors. Each pair of X-ray source-detectors is responsible for only one local angular interval. The system structure is intuitive, the acquisition tasks are clearly defined, and it facilitates hardware layout, control management, and engineering debugging.

[0008] To achieve the above objectives, the technical solution adopted by this invention is as follows: This invention discloses a multi-level electron beam shift imaging method for nine-source CT, comprising the following steps, S1. Nine pairs of X-ray sources and detectors are arranged within a finite angular arc range of 0° to 90° outside the object being inspected, so that the nine pairs of X-ray sources and detectors correspond to nine consecutive 10° angle intervals respectively. S2. Control each pair of X-ray sources and detectors to perform local scanning in their corresponding 10° angle range using electron beam deflection, and collect finite angle projection data according to the preset angle step size; S3. Set at least three ray energy levels, and perform staggered acquisition of the nine angle intervals according to the preset energy level-angle correspondence to obtain mixed energy level finite angle projection data covering the entire finite angle range from 0° to 90°. S4. Preprocess the finite-angle projection data of the mixed energy level to obtain standardized mixed energy level projection data that meets the input requirements of the diffusion model; S5. Input the standardized mixed energy level projection data into the pre-trained diffusion model, learn the mapping relationship between the mixed energy level finite angle projection data and the 90° finite angle projection data of each target energy level through the diffusion model, and map the mixed energy level finite angle projection data into the 90° finite angle projection data corresponding to the first energy level, the second energy level and the third energy level respectively. S6. Input the 90° finite angle projection data of the three energy levels obtained in step S5 into the finite angle reconstruction model based on diffusion prior and data consistency constraints, and perform iterative reconstruction on the projection data of each energy level to obtain the reconstructed images of the corresponding three energy levels. S7. Output the reconstructed images of the three energy levels for subsequent image analysis, material identification, defect detection, security inspection identification, or target identification.

[0009] The nine pairs of X-ray sources and detectors are arranged in a fan-shaped arc array from 0° to 90°. If the X-ray sources are arranged in a fan-shaped arc array from 0° to 90°, the detectors are arranged in a fan-shaped arc array from 180° to 270° on the opposite side of the X-ray sources. The object under inspection is set in the imaging center area, and the nine X-ray sources are arranged sequentially along the arc direction. The detectors corresponding to each X-ray source are set on the opposite side of the projection path to receive the X-ray projection signal after passing through the object under inspection.

[0010] The nine pairs of X-ray source-detectors correspond to the following angle ranges: the first pair corresponds to an angle range of 0° to 10°; the second pair corresponds to an angle range of 10° to 20°; the third pair corresponds to an angle range of 20° to 30°; the fourth pair corresponds to an angle range of 30° to 40°; the fifth pair corresponds to an angle range of 40° to 50°; the sixth pair corresponds to an angle range of 50° to 60°; the seventh pair corresponds to an angle range of 60° to 70°; the eighth pair corresponds to an angle range of 70° to 80°; and the ninth pair corresponds to an angle range of 80° to 90°.

[0011] In step S2, the preset angle step size is 0.25°. Each pair of X-ray source-detector forms multiple equivalent emission positions within its corresponding 10° angle range by the offset of the electron beam inside the X-ray source, thereby sequentially completing the projection acquisition of multiple sub-angle positions.

[0012] In step S3, the at least three ray energy levels include a first energy level, a second energy level, and a third energy level, and the three energy levels adopt the following staggered sampling method: the first energy level collects data in the angle range of 0° to 10°, 30° to 40°, and 60° to 70°; the second energy level collects data in the angle range of 10° to 20°, 40° to 50°, and 70° to 80°; and the third energy level collects data in the angle range of 20° to 30°, 50° to 60°, and 80° to 90°.

[0013] The first energy level corresponds to the data collected by the 1st, 4th, and 7th pairs of X-ray source-detectors; the second energy level corresponds to the data collected by the 2nd, 5th, and 8th pairs of X-ray source-detectors; and the third energy level corresponds to the data collected by the 3rd, 6th, and 9th pairs of X-ray source-detectors.

[0014] In step S4, the preprocessing includes one or more of the following: dark field correction, gain correction, geometric correction, detector response correction, normalization, logarithmic transformation, angle alignment, noise suppression, and data format unification.

[0015] In step S5, the diffusion model is used to separate the projection information of different energy levels and complete the missing angle information. The diffusion model takes the mixed energy level finite angle projection data as the condition input and outputs the 90° finite angle projection data corresponding to the first energy level, the second energy level and the third energy level respectively.

[0016] In step S6, the finite angle reconstruction model based on diffusion prior and data consistency constraints introduces both diffusion image prior and projection domain data consistency constraints during the reconstruction process. This allows the reconstructed image to satisfy the consistency of the acquired projection data while using diffusion prior to suppress finite angle artifacts and restore image structural details.

[0017] This invention discloses a multi-level electron beam shift imaging system for nine-source CT, including an array acquisition module for arranging nine pairs of X-ray sources and detectors in a circular arc range of 0° to 90° outside the subject, and controlling each X-ray source to perform projection acquisition by electron beam shift within the corresponding 10° angle range. The energy level control module is used to set at least three ray energy levels and control the interleaved energy level sampling in each angle interval according to the preset energy level-angle correspondence. The data construction module is used to combine the projection data collected from nine angular intervals in angular order to construct mixed energy level finite angle projection data covering the range of 0° to 90°. The preprocessing module is used to perform dark field correction, gain correction, geometric correction, normalization, logarithmic transformation, angle alignment, noise suppression, and data format unification on the finite angle projection data of the mixed energy level. The mapping module is used to call the diffusion model to map the mixed energy level finite angle projection data into 90° finite angle projection data corresponding to the first energy level, the second energy level, and the third energy level, respectively. The reconstruction module is used to call the finite angle reconstruction model based on diffusion prior and data consistency constraints to perform finite angle reconstruction on the 90° finite angle projection data of the three energy levels respectively; The output module is used to output the reconstructed images corresponding to the three energy levels.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. The data acquisition structure is clear and easy to implement in engineering. This invention divides a finite angle range of 0° to 90° into nine consecutive 10° angle intervals and sets up nine pairs of X-ray source-detectors accordingly. Each pair of X-ray source-detectors is responsible for only one local angle interval. The system structure is intuitive, the acquisition tasks are clearly defined, and it is convenient for hardware layout, control management, and engineering debugging.

[0020] 2. Reduce reliance on mechanical rotation scanning Traditional CT systems typically require the X-ray source and detector to mechanically rotate around the subject. This invention, however, employs a nine-pair fixed or quasi-fixed X-ray source-detector array and utilizes electron beam deflection to achieve equivalent scanning within a local angular range. This method reduces large-scale mechanical movement, improves system stability, reduces mechanical errors, and is suitable for applications where space is limited or the subject cannot be easily rotated.

[0021] 3. Improve data acquisition speed and detection efficiency. In this invention, each pair of X-ray source-detector pairs only needs to complete local sampling within a 10° angle range. The nine pairs of acquisition units can complete acquisition sequentially or in parallel according to the system control strategy, which can effectively shorten the acquisition time compared to the traditional rotating scanning method. At the same time, the multi-level adopts an interleaved segmented acquisition method, which does not require each level to complete a complete 90° scan separately, thereby reducing repeated sampling and improving the multi-level imaging efficiency.

[0022] 4. Multi-level data acquisition is more efficient. This invention assigns three energy levels to different angular ranges. For example, the first energy level corresponds to 0° to 10°, 30° to 40°, and 60° to 70°; the second energy level corresponds to 10° to 20°, 40° to 50°, and 70° to 80°; and the third energy level corresponds to 20° to 30°, 50° to 60°, and 80° to 90°. The three energy levels collectively cover the 0° to 90° angular region, avoiding the problem of repeatedly scanning the entire angular region level by level, thus reducing the acquisition burden.

[0023] 5. It can fully utilize the complementary information between angles and energy levels. Since different angle intervals are collected from different energy levels, the raw data contains both angle information and energy level information. This invention learns the mapping relationship between the finite-angle projection data of mixed energy levels and the projection data of each target energy level through a diffusion model. It can make full use of angle continuity, structural correlation and energy level complementarity, thereby achieving the separation of different energy level information and the completion of missing angle information.

[0024] 6. It helps reduce artifacts in finite-angle reconstruction. Limited-angle CT reconstruction is prone to artifacts such as tailing, stretching, and structural loss. This invention first uses a diffusion model to map mixed-energy-level data into 90° limited-angle projection data corresponding to each energy level, and then performs reconstruction using a reconstruction model based on diffusion priors and data consistency constraints. This process can improve the structural recovery capability under limited-angle conditions by introducing depth prior information while maintaining the consistency of the acquired data.

[0025] 7. Improve the quality of reconstructed images The reconstruction process of this invention not only relies on traditional projection inversion relationships but also incorporates a diffusion prior model to constrain the image structure, resulting in better performance in edge preservation, detail recovery, noise suppression, and artifact reduction. Compared to traditional reconstruction of mixed-energy-level finite-angle data, this invention can obtain more stable and clearer sub-energy-level images. Attached Figure Description

[0026] Figure 1 This is a flowchart of the multi-level electron beam shift imaging method of nine-source CT in this invention; Figure 2 This is a schematic diagram of the arrangement of nine pairs of radiation sources and detectors in this invention; Figure 3 This is a schematic diagram of single-angle region electron beam deflection sampling in this invention; Figure 4 This is a diagram showing the correspondence between the three energy levels and the nine corner regions in this invention; Figure 5 This is a schematic diagram of the energy level mapping in the diffusion model of this invention; Figure 6 This is a schematic diagram of the finite angle reconstruction result in this invention; Figure 7 This is a flowchart of the algorithm of the present invention.

[0027] In the diagram, 1 is the radiation source, 2 is the detector, and 3 is the object being inspected. Detailed Implementation

[0028] The present invention will be further described below: Please see Figure 1-7 .

[0029] Example 1: Nine-Source CT Multi-Level Electron Beam Migration Imaging Method This embodiment provides a multi-level electron beam shift imaging method for nine-source CT, the method comprising the following steps.

[0030] Step S1: Arrange nine pairs of X-ray source-detector arrays like Figure 2 As shown, nine pairs of X-ray sources 1 and detectors 2 are arranged within a limited angular range of 0° to 90° outside the object under inspection 3. The object under inspection 3 is located in the imaging center area. The nine X-ray sources 1 are arranged sequentially along an arc direction from 0° to 90°. The nine detectors 2 corresponding to each X-ray source 1 are located on the opposite side of the X-ray propagation path. The object under inspection 3 is located at the imaging center O. The nine X-ray sources 21-29 are arranged sequentially along an arc direction from 0° to 90°, and each corresponds to one of the nine consecutive 10° angle intervals. The detectors 31-39 corresponding to each X-ray source are located on the opposite side of the projection path to receive the projection signal after passing through the object under inspection 3.

[0031] Nine pairs of radiation sources 1 and detectors 2 are each responsible for nine consecutive 10° angle intervals, specifically: ; With the above arrangement, the entire 90° finite angle range is divided into nine local angle domains, and each acquisition unit is only responsible for one small angle domain, which helps to reduce the control complexity of a single acquisition unit.

[0032] Step S2: Perform local angle sampling using electron beam deflection. like Figure 3 As shown, within each 10° angle interval, the corresponding X-ray source 1 does not require large-scale mechanical rotation. Instead, multiple equivalent emission positions are formed by the deflection of the electron beam within the X-ray source 1. Each equivalent emission position corresponds to a sub-angle projection direction. The X-ray source and detector are relatively fixed, and the electron beam deflects sequentially within the X-ray source in a preset direction to form multiple equivalent emission positions with different sub-angles. This allows for the acquisition of multiple sets of projection data within a local angular domain from 0° to 10°. The sampling step size between adjacent sub-angles is Δθ = 0.25°.

[0033] In this embodiment, the preferred angular step size for electron beam offset sampling is 0.25°. Therefore, multiple sub-angle sampling positions can be formed within each 10° angle interval. For example, within the range of 0° to 10°, the first pair of X-ray sources 1-detectors 2 sequentially acquire multiple sets of projection data at 0°, 0.25°, 0.5°, 0.75° up to near 10° through electron beam offset.

[0034] The other eight pairs of X-ray sources 1 and detectors 2 complete local projection acquisition in their respective angular ranges using the same method. By employing electron beam deflection, the need for mechanical scanning can be reduced, improving acquisition stability and speed.

[0035] Step S3: Perform staggered sampling of the three energy levels. like Figure 4 As shown, the system is configured with three ray energy levels, denoted as the first, second, and third energy levels. The three energy levels are sampled alternately according to a preset angle segmentation rule.

[0036] In this embodiment, the correspondence between the three energy levels and the nine angular intervals is as follows: ; This staggered acquisition method allows the three energy levels to collectively cover a finite angular range from 0° to 90°. Compared to the traditional level-by-level scanning method, this embodiment eliminates the need for the first, second, and third energy levels to each completely scan from 0° to 90°, thereby reducing redundant sampling and improving acquisition efficiency.

[0037] Step S4: Construct finite-angle projection data of the hybrid energy level and preprocess the projection data. After collecting data in nine angular intervals, the projection data obtained in each angular interval are arranged and combined in angular order to construct mixed energy level finite-angle projection data covering 0° to 90°.

[0038] The mixed energy level finite-angle projection data continuously covers 0° to 90° in the angular dimension, but is staggered in the energy level dimension. That is, data in different angular intervals correspond to different ray energy levels.

[0039] For example, 0° to 10° is the data for the first energy level, 10° to 20° is the data for the second energy level, 20° to 30° is the data for the third energy level, 30° to 40° is the data for the first energy level again, and so on.

[0040] Before inputting the mixed energy level finite-angle projection data into the diffusion model, it is preprocessed to improve data quality and standardize the data format.

[0041] The preprocessing process may include: 1. Dark field correction, used to eliminate the influence of dark current in detector 2; 2. Gain correction, used to correct inconsistencies in the response of detector 2; 3. Geometric correction, used to correct geometric errors between X-ray source 1, the object under inspection 3, and detector 2; 4. Normalization processing is used to unify the data range between different energy levels and different detector channels; 5. Logarithmic transformation, used to convert detection intensity data into line integral projection data; 6. Angle alignment, used to ensure that the angle order is consistent across different angle ranges; 7. Noise suppression, used to reduce the impact of random noise on subsequent mapping and reconstruction; 8. The data format is standardized to meet the requirements of the input tensor or matrix format for the diffusion model.

[0042] After preprocessing, standardized mixed energy level finite-angle projection data are obtained.

[0043] Step S5: Perform energy level mapping using a diffusion model. like Figure 5 As shown, the standardized mixed-level finite-angle projection data is input into a pre-trained diffusion model. This diffusion model is used to learn the mapping relationship between the mixed-level finite-angle projection data and the projection data of the three target levels.

[0044] In this embodiment, the input to the diffusion model is mixed energy level projection data covering 0° to 90°, and the output is: 90° finite angle projection data corresponding to the first energy level; 90° finite angle projection data corresponding to the second energy level; The 90° finite angle projection data corresponding to the third energy level.

[0045] Because the original data acquisition process only collected data from three 10° angle intervals for each energy level, the data from the remaining angle intervals are missing data for any given energy level. The diffusion model learns the structural correlations and statistical relationships between different angles and energy levels to separate energy level information and complete missing angle information.

[0046] For example, for the first energy level, the actual collected data comes from 0° to 10°, 30° to 40° and 60° to 70°. The diffusion model needs to infer the projection data of the first energy level in the range of 10° to 30°, 40° to 60° and 70° to 90° based on the mixed data, so as to form the complete 90° finite angle projection data of the first energy level.

[0047] Step S6: Finite angle reconstruction based on diffusion prior and data consistency constraints The 90° finite-angle projection data of the three energy levels obtained in step five are input into the finite-angle reconstruction model. This reconstruction model combines diffusion priors and data consistency constraints to independently reconstruct the projection data of each energy level.

[0048] Specifically, for each energy level, the reconstruction process may include: ① Initialize the reconstructed image of the corresponding energy level; ② Perform orthographic projection on the current reconstructed image to obtain simulated projection data; ③ Compare the simulated projection data with the 90° finite angle projection data corresponding to the energy level; ④ Construct data consistency constraints based on the differences between the two; ⑤ Use diffusion priors to constrain and correct image structure; ⑥ Iteratively update the reconstructed image until the preset number of iterations or convergence conditions are met.

[0049] In this way, the reconstructed model can mitigate finite-angle artifacts and recover edge, texture, and internal structural details while maintaining the consistency of the projected data, such as... Figure 6 This is a schematic diagram of the finite angle reconstruction result.

[0050] Step S7: Output the reconstructed image of the three energy levels. After finite angle reconstruction, the system outputs reconstructed images corresponding to the three energy levels, namely: First energy level reconstructed image; Second energy level reconstructed image; Reconstructed image of the third energy level.

[0051] The reconstructed images of the three energy levels can be used individually to observe the internal structure of the object under inspection, or they can be used in combination for material decomposition, material identification, defect detection, hazardous material identification, or target classification.

[0052] Example 2: Nine-Source CT Multi-Level Electron Beam Shift Imaging System This embodiment provides a nine-source CT multi-level electron beam migration imaging system for implementing the above-described method. The system includes an array acquisition module, an energy level control module, a data construction module, a preprocessing module, a mapping module, a reconstruction module, and an output module.

[0053] 1. Array acquisition module The array acquisition module is used to arrange nine pairs of X-ray sources 1 and detectors 2 within a 0° to 90° arc range outside the object under inspection 3. Each pair of X-ray source 1 and detector 2 corresponds to a 10° angle interval.

[0054] The array acquisition module also includes an electron beam deflection controller, used to control the electron beam inside each X-ray source 1 to deflect according to a preset trajectory and a preset step size to form multiple equivalent emission positions. In a preferred embodiment, the angular step size corresponding to the electron beam deflection is 0.25°.

[0055] 2. Energy Level Control Module The energy level control module is used to set the first energy level, the second energy level, and the third energy level, and to control different X-ray sources 1 and detector 2 to collect data using the corresponding energy level within the corresponding angle range.

[0056] In this embodiment, the energy level control module controls the first, fourth, and seventh pairs of X-ray source 1-detector 2 to use the first energy level for acquisition; controls the second, fifth, and eighth pairs of X-ray source 1-detector 2 to use the second energy level for acquisition; and controls the third, sixth, and ninth pairs of X-ray source 1-detector 2 to use the third energy level for acquisition.

[0057] 3. Data Construction Module The data construction module is used to receive projection data collected from nine angular intervals and combine them in angular order to generate mixed energy level projection data covering a limited angular range from 0° to 90°.

[0058] 4. Preprocessing module The preprocessing module is used to correct and standardize the mixed energy level projection data. The preprocessing includes dark field correction, gain correction, geometric correction, normalization, logarithmic transformation, angle alignment, noise suppression, and data format unification.

[0059] 5. Mapping Module The mapping module is used to invoke a pre-trained diffusion model. This diffusion model takes finite-angle projection data of the mixed energy levels as input and outputs 90° finite-angle projection data corresponding to each of the three energy levels.

[0060] 6. Rebuild Module The reconstruction module is used to call the finite angle reconstruction model based on diffusion priors and data consistency constraints to reconstruct the 90° finite angle projection data of the three energy levels respectively.

[0061] 7. Output Module The output module is used to output the reconstructed images corresponding to the first, second, and third energy levels, and can provide them to subsequent image analysis, material identification, defect detection, or target identification modules.

[0062] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A multi-level electron beam shift imaging method for nine-source CT, characterized in that: Includes the following steps, S1. Nine pairs of X-ray sources and detectors are arranged within a finite angular arc range of 0° to 90° outside the object being inspected, so that the nine pairs of X-ray sources and detectors correspond to nine consecutive 10° angle intervals respectively. S2. Control each pair of X-ray sources and detectors to perform local scanning in their corresponding 10° angle range using electron beam deflection, and collect finite angle projection data according to the preset angle step size; S3. Set at least three ray energy levels, and perform staggered acquisition of the nine angle intervals according to the preset energy level-angle correspondence to obtain mixed energy level finite angle projection data covering the entire finite angle range from 0° to 90°. S4. Preprocess the finite-angle projection data of the mixed energy level to obtain standardized mixed energy level projection data that meets the input requirements of the diffusion model; S5. Input the standardized mixed energy level projection data into the pre-trained diffusion model, learn the mapping relationship between the mixed energy level finite angle projection data and the 90° finite angle projection data of each target energy level through the diffusion model, and map the mixed energy level finite angle projection data into the 90° finite angle projection data corresponding to the first energy level, the second energy level and the third energy level respectively. S6. Input the 90° finite angle projection data of the three energy levels obtained in step S5 into the finite angle reconstruction model based on diffusion prior and data consistency constraints, and perform iterative reconstruction on the projection data of each energy level to obtain the reconstructed images of the corresponding three energy levels. S7. Output the reconstructed images of the three energy levels for subsequent image analysis, material identification, defect detection, security inspection identification, or target identification.

2. The multi-level electron beam shift imaging method for nine-source CT according to claim 1, characterized in that: The nine pairs of X-ray sources and detectors are arranged in a fan-shaped arc array from 0° to 90°. The object under inspection is set in the imaging center area. The nine X-ray sources are arranged sequentially along the arc direction. The detectors corresponding to each X-ray source are set on the opposite side of the projection path to receive the X-ray projection signal after passing through the object under inspection.

3. The multi-level electron beam shift imaging method for nine-source CT according to claim 2, characterized in that: The nine pairs of X-ray source-detectors correspond to the following angle ranges: the first pair corresponds to an angle range of 0° to 10°; the second pair corresponds to an angle range of 10° to 20°; the third pair corresponds to an angle range of 20° to 30°; the fourth pair corresponds to an angle range of 30° to 40°; the fifth pair corresponds to an angle range of 40° to 50°; the sixth pair corresponds to an angle range of 50° to 60°; the seventh pair corresponds to an angle range of 60° to 70°; the eighth pair corresponds to an angle range of 70° to 80°; and the ninth pair corresponds to an angle range of 80° to 90°.

4. The multi-level electron beam shift imaging method for nine-source CT according to claim 1, characterized in that: In step S2, the preset angle step size is 0.25°. Each pair of X-ray source-detector forms multiple equivalent emission positions within its corresponding 10° angle range by the offset of the electron beam inside the X-ray source, thereby sequentially completing the projection acquisition of multiple sub-angle positions.

5. The multi-level electron beam shift imaging method for nine-source CT according to claim 1, characterized in that: In step S3, the at least three ray energy levels include a first energy level, a second energy level, and a third energy level, and the three energy levels adopt the following staggered sampling method: the first energy level collects data in the angle range of 0° to 10°, 30° to 40°, and 60° to 70°; the second energy level collects data in the angle range of 10° to 20°, 40° to 50°, and 70° to 80°; and the third energy level collects data in the angle range of 20° to 30°, 50° to 60°, and 80° to 90°.

6. The multi-level electron beam shift imaging method for nine-source CT according to claim 5, characterized in that: The first energy level corresponds to the data collected by the 1st, 4th, and 7th pairs of X-ray source-detectors; the second energy level corresponds to the data collected by the 2nd, 5th, and 8th pairs of X-ray source-detectors; and the third energy level corresponds to the data collected by the 3rd, 6th, and 9th pairs of X-ray source-detectors.

7. The multi-level electron beam shift imaging method for nine-source CT according to claim 1, characterized in that: In step S4, the preprocessing includes one or more of the following: dark field correction, gain correction, geometric correction, detector response correction, normalization, logarithmic transformation, angle alignment, noise suppression, and data format unification.

8. The multi-level electron beam shift imaging method for nine-source CT according to claim 1, characterized in that: In step S5, the diffusion model is used to separate the projection information of different energy levels and complete the missing angle information. The diffusion model takes the mixed energy level finite angle projection data as the condition input and outputs the 90° finite angle projection data corresponding to the first energy level, the second energy level and the third energy level respectively.

9. A multi-level electron beam shift imaging method for nine-source CT according to claim 1, characterized in that: In step S6, the finite angle reconstruction model based on diffusion prior and data consistency constraints introduces both diffusion image prior and projection domain data consistency constraints during the reconstruction process. This allows the reconstructed image to satisfy the consistency of the acquired projection data while using diffusion prior to suppress finite angle artifacts and restore image structural details.

10. An imaging system for the multi-level electron beam shift imaging method of nine-source CT as described in claim 1, characterized in that: It includes an array acquisition module, which is used to arrange nine pairs of X-ray sources and detectors in an arc range of 0° to 90° outside the object being inspected, and to control each X-ray source to perform projection acquisition by electron beam deflection within the corresponding 10° angle range. The energy level control module is used to set at least three ray energy levels and control the interleaved energy level sampling in each angle interval according to the preset energy level-angle correspondence. The data construction module is used to combine the projection data collected from nine angular intervals in angular order to construct mixed energy level finite angle projection data covering the range of 0° to 90°. The preprocessing module is used to perform dark field correction, gain correction, geometric correction, normalization, logarithmic transformation, angle alignment, noise suppression, and data format unification on the finite angle projection data of the mixed energy level. The mapping module is used to call the diffusion model to map the mixed energy level finite angle projection data into 90° finite angle projection data corresponding to the first energy level, the second energy level, and the third energy level, respectively. The reconstruction module is used to call the finite angle reconstruction model based on diffusion prior and data consistency constraints to perform finite angle reconstruction on the 90° finite angle projection data of the three energy levels respectively; The output module is used to output the reconstructed images corresponding to the three energy levels.

Images