X-ray fluorescence imaging method and apparatus, electronic device, and storage medium

Abstract

The application relates to an X-ray fluorescence imaging method and device, electronic equipment and a storage medium, comprising: incident X-rays to a sample to be scanned to excite X-ray fluorescence photons and scattered photons in the sample to be scanned; the fluorescence photons and / or scattered photons are shot into a Compton camera detector to obtain first spatial coordinates and first deposited energies of scattering events of the fluorescence photons and the scattered photons when Compton scattering occurs during movement of the Compton camera detector, and second spatial coordinates and second deposited energies of absorption events; and image reconstruction of the Compton camera is performed according to the first spatial coordinates, the first deposited energies, the second spatial coordinates and the second deposited energies to obtain a three-dimensional image of the sample to be scanned. Thus, the problems of a large amount of noise and a low signal-to-noise ratio caused by scattered photons generated by X-ray excitation, difficult identification and imaging of fluorescence photons, and low resolution of the Compton camera for incident photons below 100 keV are solved.

Description

Technical Field

[0001] This application relates to the field of radiation imaging technology, and in particular to an X-ray fluorescence imaging method, apparatus, electronic device and storage medium. Background Technology

[0002] X-ray fluorescence CT (Computed Tomograph) is an imaging modality that can acquire molecular and functional information of a target. Compared to conventional X-ray imaging, it offers higher imaging contrast and sensitivity, and has attracted much attention in recent years. Traditional XFCT (X-ray fluorescence Compton Tomograph) imaging systems typically require a very small-aperture mechanical collimator to obtain the incident direction of fluorescence photons, resulting in significant photon loss and reduced detection efficiency. The Compton camera, however, uses electronic collimation to acquire incident direction information, eliminating the need for a mechanical collimator and thus achieving higher detection efficiency. Originally used for astronomical observations, the Compton camera has since been widely applied in environmental radiation detection, medical imaging, proton therapy, and many other fields due to its unique imaging capabilities. Furthermore, the Compton camera can achieve three-dimensional imaging with single-view or fewer-view scanning, thus saving scanning time.

[0003] To achieve rapid single-angle scanning of three-dimensional X-ray fluorescence imaging, using the Compton camera mode for X-ray fluorescence imaging is a novel and worthwhile approach. In 2016, Vernekohl et al. used the Monte Carlo radiation transport method to simulate X-ray fluorescence imaging under a Compton camera, simulating current detection techniques, especially realistic energy resolution, to demonstrate its feasibility. However, this work only considered simulations under relatively ideal experimental conditions: the incident light was ideal 82 keV monochromatic light, the detector had good energy and spatial resolution, and a very large-area fan-shaped detector was used to obtain projection data from the entire field of view. These conditions are difficult to achieve in real medical experimental environments.

[0004] In fact, the X-ray fluorescence Compton camera imaging mode has not yet been experimentally realized, mainly due to several challenges. First, X-ray fluorescence imaging inherently presents challenges: when X-rays excite fluorescent photons, a large number of scattered photons are usually present, leading to significant noise and a low signal-to-noise ratio, making it difficult to identify and image the fluorescent photons. For traditional XFCT, since the detected projection signal is usually an integrated signal, polynomial fitting methods can be used to remove the scattering background and extract the fluorescence peak signal intensity from the integrated energy spectrum of the projection data. However, for Compton camera imaging, the data required for reconstruction is usually the independent information of each photon, making it impossible to use energy spectrum fitting methods to remove scattering. Second, the Compton camera faces significant challenges in reconstructing low-energy incident photons below 100 keV. The negative impact of the Doppler broadening effect becomes very significant, greatly reducing the accuracy of the Compton scattering angle. Third, traditional Compton cameras are typically used in low-flux radiation environments, so the count rate requirement for the detector is not high. However, X-ray fluorescence photons are usually excited by X-ray machines, and the photon flux is enormous. Therefore, the detector is required to have not only good spatial and energy resolution, but also a high count rate, which is very challenging. Summary of the Invention

[0005] This application provides an X-ray fluorescence imaging method, device, electronic device, and storage medium to solve the problems of large noise and low signal-to-noise ratio caused by scattered photons generated by X-ray excitation, which makes it difficult to identify and image fluorescence photons, and the low resolution of the Compton camera for incident photons below 100 keV. An imaging system capable of X-ray fluorescence imaging is constructed to achieve high-resolution reconstruction of the Compton camera under incident photon energy conditions below 100 keV.

[0006] The first aspect of this application provides an X-ray fluorescence imaging method, comprising the following steps: incident X-rays onto a sample to be scanned, exciting X-ray fluorescence photons and scattered photons of fluorescent elements in the sample; based on a preset incident angle, incident the fluorescence photons and / or the scattered photons into a Compton camera detector, and acquiring the first spatial coordinates and first deposition energy of the scattering event when the fluorescence photons and the scattered photons undergo Compton scattering during the movement of the Compton camera detector, as well as the second spatial coordinates and second deposition energy of the absorption event; and reconstructing the image of the Compton camera based on the first spatial coordinates, the first deposition energy, the second spatial coordinates, and the second deposition energy to obtain a three-dimensional image of the sample to be scanned.

[0007] Optionally, the preset reconstruction algorithm is:

[0008]

[0009] in, Let j be the voxel of the image after (l+1) iterations, where l is an integer. Let j be the voxel of the image after l iterations, and T be the voxel of the image. ij Let S be the system matrix. j Let i be the event index, j be the voxel index, N be the total number of events, M be the total number of voxels, k be the voxel index, and T be the sensitivity matrix. ik For the elements of the system matrix, Let k be the voxel of the image after l iterations.

[0010] Optionally, the system matrix is:

[0011]

[0012] Among them, v j Let P(y) be the imaging space volume of voxel j. i |x, E0) is the event y i The probability related to a point x in space, where x is a point in space, y i Let E0 be the total energy of the incident photon, and P(x∈v) be the event i. j Let v be the volume of point x in space at voxel j. j The probability within.

[0013] Optionally, the above-described X-ray fluorescence imaging method further includes: updating the system matrix based on a preset scattering correction algorithm, wherein the updated system matrix is:

[0014]

[0015] in, The rewritten system matrix, This indicates that event yi does not belong to the event set Y caused by scattered photons. (Scattering) The probability of.

[0016] Optionally, the above-described X-ray fluorescence imaging method further includes: determining the system matrix based on a preset Doppler broadening correction low-energy reconstruction algorithm and the scattering correction algorithm, wherein the system matrix is:

[0017]

[0018] in, For event y i With voxel v j Vectors between For vectors The angle between the scattering angle and the vertical direction, where β is the true scattering angle, θ is the measured scattering angle, K(β, E0) is the Compton scattering cross section, and σ er For the detector energy resolution, σ sr For the detector's spatial resolution, σ db The uncertainty in the reconstruction angle caused by the Doppler broadening effect, h(φ) i Let be the probability that event i originates from a scattered photon.

[0019] A second aspect of this application provides an X-ray fluorescence imaging device, comprising: an excitation module for incidenting X-rays onto a sample to be scanned, thereby exciting X-ray fluorescence photons and scattered photons of fluorescent elements in the sample; an acquisition module for incidenting the fluorescence photons and / or the scattered photons into a Compton camera detector based on a preset incident angle, and acquiring the first spatial coordinates and first deposition energy of a scattering event occurring when the fluorescence photons and the scattered photons undergo Compton scattering during the movement of the Compton camera detector, as well as the second spatial coordinates and second deposition energy of an absorption event; and an imaging module for reconstructing an image of the Compton camera based on the first spatial coordinates, the first deposition energy, the second spatial coordinates, and the second deposition energy to obtain a three-dimensional image of the sample to be scanned.

[0020] Optionally, the preset reconstruction algorithm is:

[0021]

[0022] in, Let j be the voxel of the image after (l+1) iterations, where l is an integer. Let j be the voxel of the image after l iterations, and T be the voxel of the image. ij Let S be the system matrix. j Let i be the event index, j be the voxel index, N be the total number of events, M be the total number of voxels, k be the voxel index, and T be the sensitivity matrix. ik For the elements of the system matrix, Let k be the voxel of the image after l iterations.

[0023] Optionally, the system matrix is:

[0024]

[0025] Among them, v j Let P(y) be the imaging space volume of voxel j. i |x, E0) is the event y i The probability related to a point x in space, where x is a point in space, y i Let E0 be the total energy of the incident photon, and P(x∈v) be the event i. jLet v be the volume of point x in space at voxel j. j The probability within.

[0026] Optionally, the above-mentioned X-ray fluorescence imaging device further includes: updating the system matrix based on a preset scattering correction algorithm, wherein the updated system matrix is:

[0027]

[0028] in, The rewritten system matrix, Represents event y i The event set Y that does not belong to the scattered photons (Scattering) The probability of.

[0029] Optionally, the aforementioned X-ray fluorescence imaging device further includes: determining the system matrix based on a preset Doppler broadening correction low-energy reconstruction algorithm and the scattering correction algorithm, wherein the system matrix is:

[0030]

[0031] in, For event y i With voxel v j Vectors between For vectors The angle between the scattering angle and the vertical direction, where β is the true scattering angle, θ is the measured scattering angle, K(β, E0) is the Compton scattering cross section, and σ er For the detector energy resolution, σ sr For the detector's spatial resolution, σ db The uncertainty in the reconstruction angle caused by the Doppler broadening effect, h(φ) i Let be the probability that event i originates from a scattered photon.

[0032] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the X-ray fluorescence imaging method as described in the above embodiments.

[0033] A fourth aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the X-ray fluorescence imaging method as described in the above embodiments.

[0034] Therefore, by incident X-rays onto the sample to be scanned, X-ray fluorescence photons and scattered photons of fluorescent elements in the sample are excited. Based on a preset incident angle, the fluorescence photons and / or scattered photons are injected into the Compton camera detector. The first spatial coordinates and first deposition energy of the scattering event when the fluorescence photons and scattered photons undergo Compton scattering during the movement of the Compton camera detector, and the second spatial coordinates and second deposition energy of the absorption event, are obtained. Based on the first spatial coordinates, first deposition energy, second spatial coordinates, and second deposition energy, the Compton camera image is reconstructed to obtain a three-dimensional image of the sample to be scanned. This method solves the problems of large noise and low signal-to-noise ratio caused by scattered photons generated by X-ray excitation, which makes it difficult to identify and image fluorescence photons, and the low resolution of the Compton camera for incident photons below 100 keV. An imaging system capable of X-ray fluorescence imaging has been constructed, achieving high-resolution reconstruction of the Compton camera under incident photon energy conditions below 100 keV.

[0035] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0036] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0037] Figure 1 This is a flowchart of an X-ray fluorescence imaging method provided according to an embodiment of this application;

[0038] Figure 2 This is a schematic diagram of the data acquisition and physical process of an XFCC system according to an embodiment of this application;

[0039] Figure 3 This is a schematic diagram of the data acquisition process of a Compton camera according to an embodiment of this application;

[0040] Figure 4 This is a schematic diagram of an incident photon and a scattered photon and their respective polarization vectors according to an embodiment of this application;

[0041] Figure 5 This is a schematic diagram of the theoretical variation curve of the Compton scattering KN (Klein-Nishina) cross section with azimuth angle φ according to an embodiment of this application;

[0042] Figure 6 The diagram shows the distribution of the azimuth angle φ and the trigonometric function fitting curve based on real experimental data collected according to an embodiment of this application.

[0043] Figure 7This is a block diagram of an X-ray fluorescence imaging apparatus according to an embodiment of this application;

[0044] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0045] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0046] The following description, with reference to the accompanying drawings, describes an X-ray fluorescence imaging method, apparatus, electronic device, and storage medium according to embodiments of this application. Addressing the issues mentioned in the background section regarding the significant noise and low signal-to-noise ratio caused by scattered photons generated by X-ray excitation, leading to difficulties in the identification and imaging of fluorescent photons, and the low resolution of the Compton camera for incident photons below 100 keV, this application provides an X-ray fluorescence imaging method. In this method, X-rays are incident on the sample to be scanned, exciting X-ray fluorescence photons and scattered photons of fluorescent elements in the sample. Based on a preset incident angle, the fluorescence photons and / or scattered photons are incident into the Compton camera detector. The first spatial coordinates and first deposition energy of the scattering event occurring when the fluorescence photons and scattered photons undergo Compton scattering during the movement of the Compton camera detector, and the second spatial coordinates and second deposition energy of the absorption event, are acquired. Image reconstruction of the Compton camera is performed based on the first spatial coordinates, first deposition energy, second spatial coordinates, and second deposition energy to obtain a three-dimensional image of the sample to be scanned. This solves the problems of the large amount of noise and low signal-to-noise ratio caused by scattered photons generated by X-ray excitation, which makes it difficult to identify and image fluorescent photons, as well as the low resolution of the Compton camera for incident photons below 100keV. An imaging system capable of X-ray fluorescence imaging was constructed, enabling high-resolution reconstruction of the Compton camera under incident photon energy conditions below 100keV.

[0047] Specifically, Figure 1 This is a schematic flowchart of an X-ray fluorescence imaging method provided in an embodiment of this application.

[0048] like Figure 1 As shown, this X-ray fluorescence imaging method includes the following steps:

[0049] In step S101, X-rays are incident on the sample to be scanned, exciting X-ray fluorescent photons and scattered photons of fluorescent elements in the sample to be scanned.

[0050] Specifically, such as Figure 2As shown, X-rays are incident on the sample to be scanned, exciting X-ray fluorescent photons and scattered photons of fluorescent elements in the sample.

[0051] In step S102, based on a preset incident angle, fluorescent photons and / or scattered photons are injected into the Compton camera detector, and the first spatial coordinates and first deposition energy of the scattering event when fluorescent photons and scattered photons undergo Compton scattering during the movement of the Compton camera detector are obtained, as well as the second spatial coordinates and second deposition energy of the absorption event.

[0052] It should be understood that, such as Figure 3 As shown, fluorescent photons and scattered photons enter the Compton camera detector at a 90° angle to the incident direction together, or fluorescent photons or scattered photons enter the Compton camera detector at a 90° angle to the incident direction together. The incident photons detected by the Compton camera detector undergo Compton scattering inside it. Through the response of the area array detector, the first spatial coordinates and the first deposition energy of the scattering event can be obtained, as well as the second spatial coordinates and the second deposition energy of the absorption event.

[0053] In step S103, the Compton camera image is reconstructed based on the first spatial coordinates, the first deposition energy, the second spatial coordinates, and the second deposition energy to obtain a three-dimensional image of the sample to be scanned.

[0054] Specifically, based on the first spatial coordinates, the first deposition energy, the second spatial coordinates, and the second deposition energy, the movement of the translation stage can achieve the switching of different sections of the fan beam scan, and finally form a three-dimensional image.

[0055] Optionally, in some embodiments, the preset reconstruction algorithm is:

[0056]

[0057] in, Let j be the voxel of the image after (l+1) iterations, where l is an integer. Let j be the voxel of the image after l iterations, and T be the voxel of the image. ij Let S be the system matrix. j Let i be the event index, j be the voxel index, N be the total number of events, M be the total number of voxels, k be the voxel index, and T be the sensitivity matrix. ik For the elements of the system matrix, Let k be the voxel of the image after l iterations.

[0058] Specifically, based on the list pattern data required for Compton camera reconstruction, these data are used for iterative reconstruction using the list pattern maximum likelihood expectation maximization algorithm. The voxel index values ​​can be arbitrarily selected, such as random initial values ​​or the reconstruction results of the filtered back projection algorithm.

[0059] Optionally, in some embodiments, the system matrix is:

[0060]

[0061] Among them, v j Let P(y) be the imaging space volume of voxel j. i |x, E0) is the event y i The probability related to a point x in space, where x is a point in space, y i Let E0 be the total energy of the incident photon, and P(x∈v) be the event i. j Let v be the volume of point x in space at voxel j. j The probability within.

[0062] It should be understood that, since the fluorescence photon energy of some elements is below 100 keV, the reconstruction of the Compton camera in this energy range will be affected by the Doppler broadening effect. Therefore, Doppler broadening correction is introduced. For the Compton camera reconstruction algorithm for low-energy reconstruction, the probabilistic model of the system matrix is ​​used.

[0063] Optionally, in some embodiments, the above-described X-ray fluorescence imaging method further includes: updating the system matrix based on a preset scattering correction algorithm, wherein the updated system matrix is:

[0064]

[0065] in, The rewritten system matrix, Represents event y i The event set Y that does not belong to the scattered photons (Scattering) The probability of.

[0066] It is understandable that, since the incident photons contain both effective signals, namely X-ray fluorescence photons, and scattered photons, a scattering correction algorithm based on photon polarization information is used to correct the noise of the scattered photons.

[0067] In order to solve The Klein-Nishina (KN) differential cross section needs to be discussed when linearly polarized scattered photons are incident on the detector and undergo Compton scattering again, as shown in the following equation:

[0068]

[0069] Where r0 is the classical electron radius, E2 and E0 are the scattered photon energy and the total incident photon energy, respectively, θ is the Compton scattering angle, and φ is the polarization azimuth angle, which is the angle between the projection of the scattered photon vector onto the polarization plane of the incident photon and the polarization direction of the incident photon. A schematic diagram of the incident photon, the scattered photon, and their respective polarization vectors is shown below. Figure 4 As shown, Figure 5 The variation of the Klein-Nishina differential cross section with polarization azimuth angle φ is shown.

[0070] Furthermore, when only scattered photons are incident, the distribution of the azimuth angle φ (angle window of 10°) is analyzed, and a trigonometric function nonlinear curve is fitted to this distribution as shown in the following figure. The distribution of the azimuth angle in the data collected from the actual experiment, and a schematic diagram of the trigonometric function fitting curve, are shown below. Figure 6 As shown.

[0071]

[0072] Where y0, A, ω, and φ0 are the parameters to be fitted. The fitting results show that the azimuth distribution of the actual experiment matches the theoretical analysis. Therefore, f(φ) is normalized to ensure its range is between [0, 1], resulting in the function h(φ), which is then used to construct the probability. as follows:

[0073]

[0074] Optionally, in some embodiments, the above-described X-ray fluorescence imaging method further includes: determining a system matrix based on a preset Doppler broadening correction low-energy reconstruction algorithm and a scattering correction algorithm, wherein the system matrix is:

[0075]

[0076] in, For event y i With voxel v j Vectors between For vectors The angle between the scattering angle and the vertical direction, where β is the true scattering angle, θ is the measured scattering angle, K(β, E0) is the Compton scattering cross section, and σ er For the detector energy resolution, σ sr For the detector's spatial resolution, σ db The uncertainty in the reconstruction angle caused by the Doppler broadening effect, h(φ) i Let σ be the probability that event i originates from a scattered photon. er σ sr and σ dbIt can be obtained by any reasonable method, such as numerical calculation method, Monte Carlo simulation method, experimental measurement method, etc.

[0077] Specifically, by combining the low-energy reconstruction algorithm with Doppler broadening correction and the scattering correction algorithm based on polarization information, the system matrix obtained by the CCFIRM (Compton camera-based X-ray fluorescence imaging reconstruction method) method can be obtained.

[0078] In addition to being constructed by fitting data from real experiments, this probability model can also be constructed by fitting simulation data or constructing theoretical calculation data, etc., without specific limitations here.

[0079] According to the X-ray fluorescence imaging method proposed in this application, X-rays are incident on the sample to be scanned, exciting X-ray fluorescence photons and scattered photons of fluorescent elements in the sample. Based on a preset incident angle, the fluorescence photons and / or scattered photons are injected into the Compton camera detector. The first spatial coordinates and first deposition energy of the scattering event when the fluorescence photons and scattered photons undergo Compton scattering during the movement of the Compton camera detector, and the second spatial coordinates and second deposition energy of the absorption event are obtained. The Compton camera image is reconstructed based on the first spatial coordinates, first deposition energy, second spatial coordinates, and second deposition energy to obtain a three-dimensional image of the sample to be scanned. This solves the problems of large noise and low signal-to-noise ratio caused by scattered photons generated by X-ray excitation, which makes it difficult to identify and image fluorescence photons, and the low resolution of the Compton camera for incident photons below 100 keV. An imaging system capable of X-ray fluorescence imaging is constructed, achieving high-resolution reconstruction of the Compton camera under incident photon energy conditions below 100 keV.

[0080] Next, the X-ray fluorescence imaging apparatus according to embodiments of this application is described with reference to the accompanying drawings.

[0081] Figure 7 This is a block diagram of an X-ray fluorescence imaging device according to an embodiment of this application.

[0082] like Figure 7 As shown, the X-ray fluorescence imaging device 10 includes: an excitation module 100, an acquisition module 200, and an imaging module 300.

[0083] The excitation module 100 is used to incident X-rays onto the sample to be scanned, exciting X-ray fluorescence photons and scattered photons of fluorescent elements in the sample; the acquisition module 200 is used to incident fluorescence photons and / or scattered photons into the Compton camera detector based on a preset incident angle, and acquire the first spatial coordinates and first deposition energy of the scattering event when fluorescence photons and scattered photons undergo Compton scattering during the movement of the Compton camera detector, as well as the second spatial coordinates and second deposition energy of the absorption event; the imaging module 300 is used to reconstruct the image of the Compton camera based on the first spatial coordinates, the first deposition energy, the second spatial coordinates and the second deposition energy to obtain a three-dimensional image of the sample to be scanned.

[0084] Optionally, in some embodiments, the preset reconstruction algorithm is:

[0085]

[0086] in, Let j be the voxel of the image after (l+1) iterations, where l is an integer. Let j be the voxel of the image after l iterations, and T be the voxel of the image. ij Let S be the system matrix. j Let i be the event index, j be the voxel index, N be the total number of events, M be the total number of voxels, k be the voxel index, and T be the sensitivity matrix. ik For the elements of the system matrix, Let k be the voxel of the image after l iterations.

[0087] Optionally, in some embodiments, the system matrix is:

[0088]

[0089] Among them, v j Let P(y) be the imaging space volume of voxel j. i |x, E0) is the event y i The probability related to a point x in space, where x is a point in space, y i Let E0 be the total energy of the incident photon, and P(x∈v) be the event i. j Let v be the volume of point x in space at voxel j. j The probability within.

[0090] Optionally, in some embodiments, the X-ray fluorescence imaging device 10 described above further includes: updating the system matrix based on a preset scattering correction algorithm, wherein the updated system matrix is:

[0091]

[0092] in, The rewritten system matrix, Represents event y i The event set Y that does not belong to the scattered photons (Scattering) The probability of.

[0093] Optionally, in some embodiments, the X-ray fluorescence imaging device 10 described above further includes: determining a system matrix based on a preset Doppler broadening correction low-energy reconstruction algorithm and a scattering correction algorithm, wherein the system matrix is:

[0094]

[0095] in, For event y i With voxel v j Vectors between For vectors The angle between the scattering angle and the vertical direction, where β is the true scattering angle, θ is the measured scattering angle, K(β, E0) is the Compton scattering cross section, and σ er For the detector energy resolution, σ sr For the detector's spatial resolution, σ db The uncertainty in the reconstruction angle caused by the Doppler broadening effect, h(φ) i Let be the probability that event i originates from a scattered photon.

[0096] It should be noted that the foregoing explanation of the X-ray fluorescence imaging method embodiment also applies to the X-ray fluorescence imaging device of this embodiment, and will not be repeated here.

[0097] According to the X-ray fluorescence imaging device proposed in this application, X-rays are incident on the sample to be scanned, exciting X-ray fluorescence photons and scattered photons of fluorescent elements in the sample. Based on a preset incident angle, the fluorescence photons and / or scattered photons are injected into the Compton camera detector. The device acquires the first spatial coordinates and first deposition energy of the scattering event when the fluorescence photons and scattered photons undergo Compton scattering during the movement of the Compton camera detector, as well as the second spatial coordinates and second deposition energy of the absorption event. Based on the first spatial coordinates, first deposition energy, second spatial coordinates, and second deposition energy, the Compton camera image is reconstructed to obtain a three-dimensional image of the sample to be scanned. This solves the problems of high noise and low signal-to-noise ratio caused by scattered photons generated by X-ray excitation, which makes the identification and imaging of fluorescence photons difficult, and the low resolution of the Compton camera for incident photons below 100 keV. It constructs an imaging system capable of X-ray fluorescence imaging, achieving high-resolution reconstruction of the Compton camera under incident photon energy conditions below 100 keV.

[0098] Figure 8A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0099] The memory 801, the processor 802, and the computer program stored on the memory 801 and capable of running on the processor 802.

[0100] When the processor 802 executes the program, it implements the X-ray fluorescence imaging method provided in the above embodiments.

[0101] Furthermore, electronic devices also include:

[0102] Communication interface 803 is used for communication between memory 801 and processor 802.

[0103] The memory 801 is used to store computer programs that can run on the processor 802.

[0104] The memory 801 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0105] If the memory 801, processor 802, and communication interface 803 are implemented independently, then the communication interface 803, memory 801, and processor 802 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be divided into address buses, data buses, control buses, etc. For ease of representation, Figure 8 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0106] Optionally, in a specific implementation, if the memory 801, processor 802, and communication interface 803 are integrated on a single chip, then the memory 801, processor 802, and communication interface 803 can communicate with each other through an internal interface.

[0107] The processor 802 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0108] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the X-ray fluorescence imaging method described above.

[0109] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0110] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified. Any process or method description in the flowcharts or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing customized logical functions or processes, and the scope of preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0111] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0112] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0113] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0114] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0115] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. An X-ray fluorescence imaging method, characterized in that, Includes the following steps: X-rays are incident on the sample to be scanned, exciting X-ray fluorescent photons and scattered photons of fluorescent elements in the sample; Based on a preset incident angle, the fluorescent photons and / or the scattered photons are injected into the Compton camera detector, and the first spatial coordinates and first deposition energy of the scattering event when the fluorescent photons and the scattered photons undergo Compton scattering during the movement of the Compton camera detector are obtained, as well as the second spatial coordinates and second deposition energy of the absorption event. as well as Based on the first spatial coordinates, the first deposition energy, the second spatial coordinates, and the second deposition energy, the Compton camera image is reconstructed to obtain a three-dimensional image of the sample to be scanned. The preset reconstruction algorithm is as follows: in, Let j be the voxel of the image after (l+1) iterations, where l is an integer. Let j be the voxel of the image after l iterations, and T be the voxel of the image. ij Let S be the system matrix. j Let i be the event index, j be the voxel index, N be the total number of events, M be the total number of voxels, k be the voxel index, and T be the sensitivity matrix. ik For the elements of the system matrix, Let k be the voxel of the image after l iterations. The system matrix is: Among them, v j Let P(y) be the imaging space volume of voxel j. i |x,E0) represents the event y i The probability related to a point x in space, where x is a point in space, y i Let E0 be the total energy of the incident photon, and P(x∈v) be the event i. j Let v be the volume of point x in space at voxel j. j The probability within; It also includes: updating the system matrix based on a preset scattering correction algorithm, wherein the updated system matrix is: in, Represented as event y i The event set Y that does not belong to the scattered photons (Scattering) The probability of; It also includes: determining the system matrix based on a pre-defined low-energy reconstruction algorithm with Doppler broadening correction and the scattering correction algorithm, wherein the system matrix is: in, For event y i With voxel v j Vectors between For vectors The angle between the scattering angle and the vertical direction, where β is the true scattering angle, θ is the measured scattering angle, K(β,E0) is the Compton scattering cross section, and σ er For the detector's energy resolution, σ sr For the detector's spatial resolution, σ db The uncertainty in the reconstruction angle caused by the Doppler broadening effect, h(φ) i Let φ be the probability that event i originates from a scattered photon, and let h(φ) be the probability model. i It can be constructed by fitting data from real experiments, or by fitting data from simulations, or by constructing data from theoretical calculations. When photons are incident on the Compton camera detector and undergo Compton scattering, the incident photons, scattered photons, and their respective polarization vectors exhibit angular distributions. Based on these azimuth angle distributions, a nonlinear curve is fitted. The nonlinear curve fitting method is as follows: Where φ is the azimuth angle, y0, A, ω, φ0 are the parameters to be fitted, and A is the amplitude. Further normalization of f(φ) ensures its range is between [0, 1], yielding the function h(φ). The probability is then constructed using h(φ). ， The Klein-Nishina differential cross section is obtained from the Compton scattering of the scattered photon after it is incident on the detector. The differential cross section is as follows: Where r0 is the classical electron radius, E2 and E0 are the scattered photon energy and the total incident photon energy, respectively, θ is the Compton scattering angle, and φ is the angle between the projection of the scattered photon vector onto the incident photon polarization plane and the incident photon polarization direction.

2. An X-ray fluorescence imaging device, characterized in that, include: The excitation module is used to incident X-rays onto the sample to be scanned, thereby exciting the X-ray fluorescent photons and scattered photons of the fluorescent elements in the sample to be scanned. The acquisition module is used to inject the fluorescent photons and / or the scattered photons into the Compton camera detector based on a preset incident angle, and acquire the first spatial coordinates and first deposition energy of the scattering event when the fluorescent photons and the scattered photons undergo Compton scattering during the movement of the Compton camera detector, as well as the second spatial coordinates and second deposition energy of the absorption event. as well as An imaging module is used to reconstruct images from a Compton camera based on the first spatial coordinates, the first deposition energy, the second spatial coordinates, and the second deposition energy to obtain a three-dimensional image of the sample to be scanned. The preset reconstruction algorithm is as follows: in, Let j be the voxel of the image after (l+1) iterations, where l is an integer. Let j be the voxel of the image after l iterations, and T be the voxel of the image. ij Let S be the system matrix. j Let i be the event index, j be the voxel index, N be the total number of events, M be the total number of voxels, k be the voxel index, and T be the sensitivity matrix. ik For the elements of the system matrix, Let k be the voxel of the image after l iterations. The system matrix is: Among them, v j Let P(y) be the imaging space volume of voxel j. i |x,E0) represents the event y i The probability related to a point x in space, where x is a point in space, y i Let E0 be the total energy of the incident photon, and P(x∈v) be the event i. j Let v be the volume of point x in space at voxel j. j The probability within; It also includes: updating the system matrix based on a preset scattering correction algorithm, wherein the updated system matrix is: Where is the rewritten system matrix. Represented as event y i The event set Y that does not belong to the scattered photons (Scattering) The probability of; It also includes: determining the system matrix based on a pre-defined low-energy reconstruction algorithm with Doppler broadening correction and the scattering correction algorithm, wherein the system matrix is: in, For event y i With voxel v j Vectors between For vectors The angle between the scattering angle and the vertical direction, where β is the true scattering angle, θ is the measured scattering angle, K(β,E0) is the Compton scattering cross section, and σ er For the detector's energy resolution, σ sr For the detector's spatial resolution, σ db The uncertainty in the reconstruction angle caused by the Doppler broadening effect, h(φ) i Let φ be the probability that event i originates from a scattered photon, and let h(φ) be the probability model. i It can be constructed by fitting data from real experiments, or by fitting data from simulations, or by constructing data from theoretical calculations. When photons are incident on the Compton camera detector and undergo Compton scattering, the incident photons, scattered photons, and their respective polarization vectors exhibit angular distributions. Based on these azimuth angle distributions, a nonlinear curve is fitted. The nonlinear curve fitting method is as follows: Where φ is the azimuth angle, y0, A, ω, φ0 are the parameters to be fitted, and A is the amplitude. Further normalization of f(φ) ensures its range is between [0, 1], yielding the function h(φ). The probability is then constructed using h(φ). ， The Klein-Nishina differential cross section is obtained from the Compton scattering of the scattered photon after it is incident on the detector. The differential cross section is as follows: Where r0 is the classical electron radius, E2 and E0 are the scattered photon energy and the total incident photon energy, respectively, θ is the Compton scattering angle, and φ is the angle between the projection of the scattered photon vector onto the incident photon polarization plane and the incident photon polarization direction.

3. An electronic device, characterized in that, Including memory and processor; The processor reads executable program code stored in the memory to run a program corresponding to the executable program code, so as to implement the X-ray fluorescence imaging method as described in claim 1.

4. A computer-readable storage medium storing a computer program, characterized in that, When the program is executed by the processor, it implements the X-ray fluorescence imaging method as described in claim 1.

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