Dual modality x-ray imaging system and method

Abstract

This invention relates to a dual-modal X-ray imaging system and method. The system includes an X-ray source, a switchable focusing device, a sample carrier, a transmission imaging detector, and a fluorescence imaging detector. The X-ray source generates and outputs X-rays that propagate along the principal optical axis. The sample carrier carries the sample and allows it to rotate and translate relative to the X-rays. The transmission imaging detector is located on the principal optical axis and downstream of the sample carrier. The switchable focusing device is movable relative to the principal optical axis to be on or off the principal optical axis. When the switchable focusing device is on the principal optical axis, the system is in XFCT imaging mode; when the switchable focusing device is off the principal optical axis, the system is in XCT imaging mode.

Description

Technical Field

[0001] This invention relates to the field of X-ray imaging technology, and more specifically to a dual-modal X-ray imaging system and method. Background Technology

[0002] In the fields of nondestructive testing and biomedical imaging based on laboratory light sources, X-ray computational tomography (XCT) and X-ray fluorescence computational tomography (XFCT) are two important and complementary imaging modalities. XCT utilizes the differences in X-ray absorption and attenuation among different substances to create contrast, enabling the acquisition of high-resolution three-dimensional anatomical morphology and density structure information within a sample; while XFCT, by detecting the characteristic X-ray fluorescence generated by the sample under stimulation, can achieve highly sensitive three-dimensional imaging of elemental spatial distribution. Although XCT and XFCT are highly complementary in information acquisition, these two technologies currently typically rely on two completely independent hardware systems, which has the following significant drawbacks:

[0003] First, the hardware costs of two separate systems are high, the structure is redundant, and the space required is large. Existing XFCT / XCT dual-modal solutions are mostly simple splicing of two independent devices, each with its own independent X-ray source, sample stage, detection system, and optical path components. Among them, the X-ray tube, high-precision motorized stage, and high-sensitivity detector are all high-cost core components. Two independent systems directly lead to double the cost of equipment procurement, operation and maintenance, and use, and the equipment is huge, requiring extremely large site space.

[0004] Secondly, traditional XFCT imaging suffers from weak fluorescence signals, poor signal-to-noise ratio, long acquisition times, and low efficiency. Existing full-field XFCT systems mostly employ cone-beam full-field excitation or pinhole collimation schemes. Laboratory light sources have low X-ray photon flux density, resulting in weak characteristic fluorescence signals generated by sample stimulation, high background noise, low spatial resolution, and requiring long acquisition times. While point-scan-based XFCT's spatial resolution is determined by the size of a single point, the large number of scan points leads to long acquisition times. Therefore, it cannot meet the application requirements of batch sample detection and in vitro tissue imaging. Summary of the Invention

[0005] The purpose of this invention is to provide a dual-modal X-ray imaging system and method that can realize both XCT and XFCT imaging through a single system, thereby solving the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides a dual-modal X-ray imaging system, comprising an X-ray source, a switchable focusing device, a sample carrier, a transmission imaging detector, and a fluorescence imaging detector. The X-ray source generates and outputs X-rays that propagate along the principal optical axis. The sample carrier carries a sample and allows the sample to rotate and translate relative to the X-rays. The transmission imaging detector is positioned on the principal optical axis and downstream of the sample carrier. The switchable focusing device is movable relative to the principal optical axis, either on or off the principal optical axis. When the switchable focusing device is on the principal optical axis, the system is in XFCT imaging mode, where it focuses the X-rays into a focused spot. This focused spot illuminates the sample, exciting it to produce fluorescence. The fluorescence imaging detector receives the fluorescence and outputs a fluorescence projection signal. When the switchable focusing device is off the principal optical axis, the system is in XCT imaging mode, where the X-rays penetrate the sample and are received by the transmission imaging detector, which outputs a transmission projection signal.

[0007] Optionally, it also includes a control device connected to the X-ray source, the switchable focusing device, the sample carrier, the transmission imaging detector, and the fluorescence imaging detector.

[0008] Optionally, the switchable focusing device includes a displacement stage and a focusing element. The focusing element is fixed to the displacement stage by a special clamp. The displacement stage is used to move the focusing element relative to the main optical axis so that the focusing element is on or off the main optical axis. The focusing element is used to focus the X-rays into a focused spot.

[0009] Optionally, the switchable focusing device further includes a positioning baffle, a first limiting protection unit, and a second limiting protection unit. The positioning baffle is disposed between the displacement stage and the sample carrying device, the first limiting protection unit is disposed between the displacement stage and the X-ray source, and the second limiting protection unit is disposed between the positioning baffle and the sample carrying device.

[0010] Optionally, the sample carrying device includes a sample stage and a sample clamp, wherein the sample is fixed on the sample stage by the sample clamp, and the sample stage is used to enable the sample to rotate and translate.

[0011] Optionally, the transmission imaging detector is an X-ray surface detector.

[0012] Optionally, the fluorescence imaging detector is an energy-dispersive single-photon counting point scanning detector.

[0013] Optionally, it also includes a protective device, in which the X-ray source, the switchable focusing device, the sample carrier, the transmission imaging detector, and the fluorescence imaging detector are all located, and the protective device is used for radiation shielding.

[0014] Another aspect of the present invention provides a dual-modal X-ray imaging method, comprising:

[0015] A dual-modal X-ray imaging system as described above is provided;

[0016] The control device controls the switchable focusing device to move to a position off the main optical axis, mounts the sample on the sample carrier, and controls the sample carrier to move with the sample so that the sample moves to the main optical axis.

[0017] XCT imaging was performed on the sample to obtain a three-dimensional XCT tomographic image of the sample;

[0018] The region of interest of the sample is determined based on the XCT three-dimensional tomographic image of the sample, and the XFCT imaging parameters are determined based on the region of interest of the sample.

[0019] The control device controls the switchable focusing device to move onto the main optical axis and performs optical path calibration;

[0020] XFCT imaging is performed on the region of interest of the sample based on XFCT imaging parameters to obtain the XFCT three-dimensional tomographic image of the sample.

[0021] The control device performs in-situ fusion of the XCT three-dimensional tomographic image and the XFCT three-dimensional tomographic image of the sample to obtain a dual-modal fused image of the sample.

[0022] Optionally, optical path calibration may be performed, specifically including:

[0023] The control device controls the movement of the sample carrier, causing the sample to move and leave the main optical axis;

[0024] The control device controls the X-ray conduction of the X-ray source. The X-rays are focused into a focused spot by a switchable focusing device. The focused spot is incident on the transmission imaging detector, which detects the two-dimensional grayscale image of the focused spot.

[0025] The control device processes the two-dimensional grayscale image of the focused spot to obtain the centroid coordinates of the spot and the coaxial deviation between the centroid coordinates of the spot and the reference coordinates of the principal optical axis.

[0026] The control device controls the switchable focusing device to make micro-translation adjustments based on the coaxial deviation between the centroid coordinates of the light spot and the reference coordinates of the principal optical axis. Each adjustment sequentially acquires a two-dimensional grayscale image of the focused light spot until the coaxial deviation between the centroid of the light spot and the reference coordinates of the principal optical axis is less than the preset value.

[0027] The control device controls the X-ray to be disconnected. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a dual-modal X-ray imaging system according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the switchable focusing device of a dual-modal X-ray imaging system according to an embodiment of the present invention;

[0030] Figure 3 This is a flowchart of a dual-modal X-ray imaging method according to an embodiment of the present invention. Detailed Implementation

[0031] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0032] like Figure 1 As shown, this embodiment of the invention provides a dual-modal X-ray imaging system, which includes an X-ray source 10, a switchable focusing device 20, a sample carrier 30, a transmission imaging detector 40, and a fluorescence imaging detector 50. The X-ray source 10 generates and outputs X-rays that propagate along the principal optical axis. The sample carrier 30 carries the sample and allows the sample to rotate and translate relative to the X-rays, with the rotation center of the sample located on the principal optical axis. The transmission imaging detector 40 is located on the principal optical axis and downstream of the sample carrier 30. The switchable focusing device 20 is configured to be movable relative to the principal optical axis to position... The switching focusing device 20 is located on or off the main optical axis. When the switching focusing device 20 is located on the main optical axis, the dual-mode X-ray imaging system is in XFCT imaging mode. The switching focusing device 20 is used to focus X-rays into a focused spot, which irradiates the sample and excites the sample to produce fluorescence. The fluorescence imaging detector 50 is used to receive the fluorescence and output the fluorescence projection signal. When the switching focusing device 20 is off the main optical axis, the dual-mode X-ray imaging system is in XCT imaging mode. After the X-rays penetrate the sample, they are received by the transmission imaging detector 40, which detects the transmission projection signal.

[0033] The dual-modal X-ray imaging system may also include a control device 60, which is connected to the X-ray source 10, the switchable focusing device 20, the sample carrier device 30, the transmission imaging detector 40, and the fluorescence imaging detector 50, respectively, for controlling the on / off state of the X-ray source, controlling the movement of the switchable focusing device 20, controlling the movement of the sample carrier device 30, receiving and processing the signals detected by the transmission imaging detector 40 and the fluorescence imaging detector 50.

[0034] X-ray source 10 may include a cone-beam X-ray tube, a high-voltage generator, an air-cooling assembly, and a fast-control shutter. The high-voltage generator is connected to the cone-beam X-ray tube and provides adjustable tube voltage and current. The X-ray tube generates a broad-spectrum cone-beam X-ray. The air-cooling assembly is connected to the cavity of the cone-beam X-ray tube and maintains a stable operating temperature through forced air convection, ensuring consistent X-ray output. The fast-control shutter is installed at the front end of the exit window of the cone-beam X-ray tube and controls the on / off state of the X-rays. A control device 60 is connected to the fast-control shutter. The core function of X-ray source 10 is to provide a uniform and stable broad-spectrum cone-beam X-ray for dual-modal imaging, simultaneously meeting the needs of XCT transmission imaging and XFCT fluorescence imaging without replacing the X-ray source, achieving low-cost reuse.

[0035] like Figure 2 As shown, the switchable focusing device 20 includes a displacement stage 21 and a focusing element 22. The focusing element 22 can be fixed to the displacement stage 21, for example, by a dedicated clamp 23. The displacement stage 21 has at least X / Y / Z-axis translation and rotational degrees of freedom about the Z and Y axes. The Y-axis translation is used to move the focusing element 22 relative to the principal optical axis, so that the focusing element 22 is on or off the principal optical axis. For example, the main body of the displacement stage 21 can be placed horizontally perpendicular to the principal optical axis, and its movement can cause the focusing element 22 to move completely into or out of the principal optical axis. The X / Z-axis translation and rotation about the Z / Y axes enable the focusing element 22 to accurately focus X-rays into a micrometer-level focused spot. The minimum step resolution of the displacement stage is better than 1 micrometer, and the rotational angle resolution is better than 0.001°, meeting the requirements of high-precision calibration. The focusing element 22 is used to focus X-rays into a high-intensity micro-focus spot with a micrometer-level diameter, which illuminates the sample and causes it to emit fluorescence. The focusing element 22 can be a capillary focusing lens.

[0036] The switchable focusing device 20 may further include a positioning baffle 24, a first limiting protection unit 25, and a second limiting protection unit 26. The positioning baffle 24 is located between the displacement stage 21 and the sample carrier 30, the first limiting protection unit 25 is located between the displacement stage 21 and the X-ray source 10, and the second limiting protection unit 26 is located between the positioning baffle 24 and the sample carrier 30. The positioning baffle 24 serves as a reference point for determining whether the focusing element 22 is located on the main optical axis, and the first and second limiting protection units are used to prevent the focusing element 22 from colliding with other surrounding components. Specifically, the positioning baffle 24 is equipped with a position sensor. When the displacement stage 21 moves the focusing element 22 to the main optical axis, it triggers a position sensor signal. The control device 60 controls the displacement stage 21 to stop moving based on this position signal. The positioning baffle 24 acts as a passive physical reference, used to ensure repeatability of positioning accuracy through mechanical alignment after each switching, thereby indirectly ensuring that the focusing element 22 is located on the main optical axis.

[0037] The core functions of the switchable focusing device 20 are: 1) Switching imaging modes: When the stage 21 positions the focusing element 22 on the main optical axis, it is locked after mechanical pre-positioning and optical fine calibration. The diverging X-rays emitted by the cone beam X-ray are focused by the focusing element 22 into a high-intensity micro-focus spot with a diameter of micrometers, providing a high-throughput excitation source for XFCT point scanning; when the stage 21 moves the focusing element 22 away from the main optical axis (i.e. completely removed from the main optical axis), the cone beam X-rays are emitted along the main optical axis without obstruction, irradiating the sample in the entire field, providing a uniform full-field excitation source for XCT transmission imaging; 2) Optical path self-calibration function: In conjunction with the transmission imaging detector, the center position, size, and shape of the focused spot are detected, and the high-precision coaxial calibration between the focused spot and the main optical axis is achieved through the micro-adjustment of the stage 21.

[0038] The sample carrier device 30 may include a sample stage and a sample clamp. The sample is fixed to the sample stage by the sample clamp. The sample stage has at least three degrees of freedom for translation along the X / Y / Z axes and rotation around the Z-axis, enabling three-dimensional translation and 360° continuous rotation of the sample. The displacement resolution is better than 1 micrometer, and the rotation angle resolution is better than 0.001°. The core function of the sample carrier device 30 is that a single sample stage is used throughout the dual-modal imaging process, and the sample only needs to be clamped once. There is no relative displacement or secondary clamping during the switching between XCT and XFCT modalities, ensuring that the physical coordinate system of the two imaging processes is completely unified, achieving true in-situ imaging, and eliminating mechanical errors in image registration from the hardware source.

[0039] The transmission imaging detector 40 can be an X-ray surface detector, such as a CMOS (Complementary Metal-Oxide-Semiconductor) flat panel detector or an amorphous silicon flat panel detector. The detection surface of the transmission imaging detector 40 faces the X-ray principal optical axis and is coaxially arranged with the exit window of the X-ray tube. The center of the detection surface is completely coincident with the principal optical axis, with no optical path obstruction throughout the entire process. The core functions of the transmission imaging detector 40 are: 1) XCT imaging function: In XCT imaging mode, it acquires the X-ray transmission attenuation signal after penetrating the sample and obtains sample projection data at different rotation angles, providing raw data for XCT three-dimensional structure reconstruction; 2) Optical path calibration function: In the XFCT optical path calibration stage, when there is no sample obstruction, it directly acquires the focused spot image, providing raw data for optical path coaxiality calibration, spot size adjustment, and defocus correction, realizing optical path self-calibration without additional hardware.

[0040] The fluorescence imaging detector 50 can be an energy-dispersive single-photon counting point-scan detector, such as a silicon drift detector (SDD). The fluorescence imaging detector 50 is fixedly mounted on the side of the shared sample-carrying module via a three-dimensional adjustment bracket. Its detection surface is orthogonal to the X-ray principal axis at 90°, with the center of the detection surface directly facing the focused spot illumination area on the sample. This maximizes the reception of characteristic fluorescence signals generated by the sample's excitation, while avoiding signal crosstalk and saturation caused by direct incident X-rays from the principal axis onto the detector. The detector is equipped with a multi-channel pulse amplitude analyzer, which can perform energy window filtering on the acquired fluorescence spectrum to accurately separate the characteristic fluorescence peaks of the target element and filter out scattered background noise. The core function of the fluorescence imaging detector 50 is to acquire characteristic X-ray fluorescence signals generated by the sample point-by-point in XFCT point-scan mode, obtain the fluorescence count rate of the target element through energy spectrum analysis, provide raw data for XFCT three-dimensional elemental distribution reconstruction, adapt to the point-by-point data acquisition requirements of micro-focus scanning, and achieve high-sensitivity detection of trace elements.

[0041] The dual-modal X-ray imaging system may also include a protective device 70, which encloses the imaging optical path area. The X-ray source 10, switchable focusing device 20, sample carrier 30, transmission imaging detector 40, and fluorescence imaging detector 50 are all located within the protective device 70, serving as radiation shielding. The control device 60 is located outside the protective device 70. The protective device 70 may employ a lead-steel composite shielding structure, with the lead layer thickness designed according to the highest X-ray tube voltage to ensure that the radiation leakage dose is below the national standard limit. The protective chamber is equipped with an electrically interlocked door, which is interlocked with a fast-control shutter for safety. The X-ray beam is automatically cut off if the chamber door is not fully closed. The core function of the protective device 70 is to shield scattered X-rays, reduce imaging background noise, and simultaneously ensure the radiation safety of operators, achieving a dual improvement in imaging quality and safety protection.

[0042] The control device 60 may include a synchronous timing controller, a data acquisition device, and a host computer. The synchronous timing controller is connected to the fast-control shutter of the X-ray source 10, the switchable focusing device 20, the sample carrier device 30, the transmission imaging detector 40, and the fluorescence imaging detector 50, respectively, to realize the synchronous timing control of all hardware in the entire system. The data acquisition device is connected to the transmission imaging detector 40 and the fluorescence imaging detector 50, respectively, to acquire the raw signals output by the detectors and transmit them to the host computer. The host computer is connected to the synchronous timing controller and the data acquisition device. The host computer has built-in optical axis calibration unit, spot analysis and calibration algorithm unit, ROI (region of interest) intelligent recognition unit, coordinate automatic transformation unit, CT image reconstruction unit, XFCT image reconstruction unit, and dual-modal image fusion unit, which can complete optical axis calibration, automatic optical path calibration, image reconstruction, ROI recognition, coordinate transformation, and dual-modal in-situ fusion. The control device has 60 core functions: it enables one-click switching of dual-modal imaging, fully automated control of the entire process, synchronous data acquisition, image reconstruction and fusion, and can automatically plan the XFCT scanning path and spot parameters based on the XCT imaging results to achieve intelligent targeted scanning.

[0043] like Figure 3 As shown, this embodiment of the invention also provides a dual-modal X-ray imaging method, which includes the following steps:

[0044] S100: Provide a dual-modal X-ray imaging system as described in the above embodiments.

[0045] After preparing the dual-modal X-ray imaging system, the entire system power should be turned on to complete the self-test and reset of each module of the system. The control device 60 confirms that the zero position of each motion axis is accurate.

[0046] S200: The control device 60 controls the switchable focusing device 20 to move to a position off the main optical axis, mounts the sample on the sample carrier device 30, and controls the sample carrier device 30 to move with the sample so that the sample moves to the main optical axis.

[0047] The switchable focusing device 20 is moved relative to the main optical axis by the control device 60, so that it is completely moved away from the main optical axis, thereby putting the system into XCT imaging mode. After the sample is mounted on the sample carrier 30, the control device 60 can move the sample carrier 30, thereby moving the sample to the main optical axis.

[0048] S300: Perform XCT imaging on the sample to obtain a three-dimensional XCT tomographic image of the sample.

[0049] Step S300 specifically includes:

[0050] S310: The control device 60 controls the X-ray source 10 to generate and emit X-rays outward. The X-rays irradiate the sample along the main optical axis without obstruction. The transmission imaging detector synchronously receives the transmitted X-rays after penetrating the sample and outputs the transmission projection signal. The control device 60 controls the sample carrying device 30 to move according to the transmission projection signal so that the area to be observed of the sample is aligned with the transmission imaging detector.

[0051] S320: The control device 60 controls the sample carrier 30 to drive the sample to rotate continuously in a preset step size, and completes the synchronous acquisition of full-angle transmission projection data within the range of 0-360°. After the control device 60 has acquired the transmission projection data, it controls the X-ray source 10 to disconnect the X-ray (for example, close the fast control shutter while keeping the X-ray tube open).

[0052] S330: The control device 60 performs three-dimensional reconstruction based on full-angle transmission projection data to obtain the XCT three-dimensional tomographic image of the sample.

[0053] S400: Determine the region of interest of the sample based on the XCT three-dimensional tomographic image of the sample, and determine the XFCT imaging parameters based on the region of interest of the sample.

[0054] In step S400, the region of interest can be selected manually or automatically identified. When selected manually, the operator uses a mouse to select the local region of interest to be analyzed. When automatically identified, the control device 60 uses a built-in image recognition algorithm to automatically identify high-density / low-density anomalous regions of the sample and mark them as regions of interest.

[0055] XFCT imaging parameters include the translation range, translation steps, rotation angle range, rotation steps, single-point integration time, and translation step size of the XFCT point scan. After the region of interest is selected, the control device 60 can automatically convert the image pixel coordinates of the region of interest into the physical motion coordinates of the sample carrier device 30. At the same time, it can automatically calculate the translation range, translation steps, rotation angle range, and rotation steps of the XFCT point scan according to the three-dimensional size and resolution requirements of the region of interest. The control device 60 can also automatically adjust the single-point integration time and translation step size of the XFCT scan according to the contrast of the XCT three-dimensional tomographic image, so as to maximize the compression of the scan time while ensuring the imaging signal-to-noise ratio.

[0056] S500: The control device 60 controls the switchable focusing device 20 to move onto the main optical axis and performs optical path calibration.

[0057] In some embodiments, step S500 specifically includes:

[0058] S510: The control device 60 controls the movement of the displacement stage 21 of the switchable focusing device 20, which drives the focusing element 22 to move and move it into the X-ray main optical axis.

[0059] S520: Control device 60 controls the sample carrier 30 to move the sample away from the main optical axis;

[0060] S530: The control device 60 controls the X-ray conduction of the X-ray source. After the X-ray is focused by the focusing element 22, it is directly incident on the transmission imaging detector 40. The transmission imaging detector 40 detects the two-dimensional grayscale image of the focused spot.

[0061] S540: The control device 60 uses the built-in spot analysis and calibration algorithm to perform Gaussian fitting and binarization processing on the two-dimensional grayscale image of the acquired focused spot, and calculates three core parameters: 1) the centroid coordinates of the spot, which are compared with the reference coordinates of the principal optical axis to obtain the coaxiality deviation; 2) the full width at half maximum (FWHM) of the spot, i.e. the effective focused spot size; 3) the morphological parameters such as the roundness and energy uniformity of the spot.

[0062] S550: The control device 60 automatically controls the switchable focusing device 20 to perform micro-translation and rotation adjustment based on the coaxiality deviation. Each adjustment acquires a spot image until the deviation between the spot centroid and the main optical axis reference coordinate is less than or equal to a preset value (e.g., ±1 micrometer).

[0063] S560: After calibration, the control device 60 controls the X-ray to disconnect; the system completes the final calibration of XFCT according to the current position of the displacement stage. If an abnormal situation occurs during the calibration process, such as severe spot deformation or no effective focused spot, the system will pop up a warning window to prompt the operator to check the installation status of the focusing element.

[0064] S600: XFCT imaging is performed on the region of interest of the sample based on XFCT imaging parameters to obtain a three-dimensional XFCT tomographic image of the sample.

[0065] In some embodiments, step S600 specifically includes:

[0066] S610: The control device 60 controls the sample carrier 30 to move the sample so that the region of interest of the sample is aligned with the focused spot of the switchable focusing device 20.

[0067] S620: The control device 60 controls the X-ray conduction of the X-ray source 10. The X-rays are focused into a micro-focus spot of a preset size by the switchable focusing device 20, which irradiates the sample and excites fluorescence. The fluorescence imaging detector 50 simultaneously collects fluorescence energy spectrum data (i.e., fluorescence projection signal).

[0068] S630: The control device 60 controls the sample carrier device 30 to drive the sample to complete the translation-rotation step-by-step point scan according to the preset scanning path: at each rotation angle, the translation scan of the entire region of interest is completed, and the fluorescence projection signal is collected point by point; after the current angle scan is completed, the sample is rotated to the next angle, and the translation scan process is repeated until the full-angle region of interest targeted scan is completed. After the scan is completed, the X-ray is disconnected.

[0069] S640: The control device 60 uses the Ordered Subset Expectation Maximization (OSEM) algorithm to perform three-dimensional reconstruction of the fluorescence projection signal of the acquired region of interest, and obtain the XFCT three-dimensional tomographic image of the sample.

[0070] S700: The control device 60 performs in-situ fusion of the XCT three-dimensional tomographic image and the XFCT three-dimensional tomographic image of the sample to obtain a dual-modal fused image of the sample.

[0071] Since the sample is only clamped once during XCT and XFCT imaging, and the entire imaging process is completed on the same shared sample stage without relative displacement or secondary clamping, the two imaging processes are in the same physical coordinate system. However, considering that the detector resolution and pixel size of the two imaging modes may differ, it is necessary to fuse the images from the two imaging modes.

[0072] Step S700 specifically includes:

[0073] S710: Perform slice extraction, extracting two-dimensional slice images I corresponding to the XFCT scan layers from the XCT 3D reconstruction volume. CT The layer is determined by the relationship between the Z coordinate of the sample carrier device 30 and the spatial position of the XCT reconstructed voxels;

[0074] S720: Perform affine transformation registration using XCT slice images I CT For reference, XFCT three-dimensional tomographic image I XF For floating images, an affine transformation model is used for geometric alignment. The affine transformation includes rotation, translation, and isotropic scaling, and its mathematical expression is:

[0075]

[0076] Where (x,y) is I XF The pixel coordinates in I, (x', y') are the transformed pixels in I. CT Corresponding coordinates in the coordinate system; θ is the rotation angle, s is the scaling factor, t x t y The translation is represented by θ. By extracting common feature points (such as sample edges, high-density particles, etc.) from the two images, the four parameters (θ, s, t) are solved using the least squares method. x,t y ), and then for I XF Bilinear interpolation resampling is performed to obtain the registered image I. XF_reg .

[0077] S730: Resolution normalization. If the pixel size of the XFCT image is different from that of the XCT image, bicubic interpolation is used to normalize the resolution. XF_reg Resampling to I CT The same pixel size ensures a one-to-one correspondence in space.

[0078] S740: Performs pseudo-color mapping and overlay fusion. The registered and resampled element distribution image is pseudo-color mapped, and then fused with the XCT grayscale image using a weighted overlay algorithm. The fusion formula is as follows:

[0079]

[0080] Where C(·) is the pseudo-color mapping function, and α and β are the fusion weights (usually α=0.5, β=0.5). The final output is a bimodal fused image with precise anatomical localization.

[0081] The dual-modal X-ray imaging device and method of this invention have the following improvements and beneficial effects compared with the prior art:

[0082] Improvement 1: A switchable focusing device 20 is adopted to achieve integrated dual-modal coaxial imaging. The focusing element 22 is moved into / out of the optical path by the displacement stage 21, and lossless modulation of X-rays "diverging across the entire field / focusing a microbeam" is achieved in a single coaxial optical path. This is the first innovation in dual-modal imaging of focusing element and cone beam in the existing technology.

[0083] Beneficial effects: 1) Maximizes the sharing of core high-cost components. The reuse rate of core components such as X-ray source 10, sample carrier device 30, detector, and control device 60 reaches 100%. The two independent devices are combined into one, reducing the hardware cost of the equipment by more than 60% and the volume by more than 70%. The structure is compact and suitable for multiple application scenarios in the laboratory and on-site testing; 2) The coaxial optical path design throughout the process ensures the consistency of the optical axis through automatic calibration after mode switching. There is no need for manual recalibration of the optical path, which greatly simplifies the operation process and significantly improves the long-term stability of the equipment.

[0084] Improvement 2: A multi-capillary focusing lens is used as the focusing element 22 to achieve high-throughput focusing of X-rays. The photon flux at the focused spot is 10,000 times higher than that of a traditional pinhole collimator. At the same time, a single-photon counting point scanning detector with a 90° orthogonal arrangement to the main optical axis is used to completely avoid crosstalk of transmitted X-rays and is equipped with an energy window filtering function to filter background noise.

[0085] Beneficial effects: 1) Significantly improves the characteristic fluorescence excitation efficiency of samples, greatly enhances the fluorescence signal intensity, and significantly shortens the single-point integration time, further improving imaging efficiency; 2) Effectively reduces background noise, improves the fluorescence signal-to-noise ratio by more than one order of magnitude, and achieves element detection limits up to 100 ppm, realizing high-sensitivity quantitative imaging of trace elements and expanding the application scenarios of the system in biomedicine, environmental monitoring and other fields.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A dual-modal X-ray imaging system, characterized in that, The system includes an X-ray source, a switchable focusing device, a sample carrier, a transmission imaging detector, and a fluorescence imaging detector. The X-ray source generates and outputs X-rays that travel along the principal optical axis. The sample carrier carries the sample and allows it to rotate and translate relative to the X-rays. The transmission imaging detector is located on the principal optical axis and downstream of the sample carrier. The switchable focusing device is movable relative to the principal optical axis, either on or off the axis. When the switchable focusing device is on the principal optical axis, the system is in XFCT imaging mode, where it focuses the X-rays into a focused spot that illuminates the sample and excites it to produce fluorescence. The fluorescence imaging detector receives the fluorescence and outputs a fluorescence projection signal. When the switchable focusing device is off the principal optical axis, the system is in XCT imaging mode, where the X-rays penetrate the sample and are received by the transmission imaging detector, which outputs a transmission projection signal.

2. The dual-modal X-ray imaging system according to claim 1, characterized in that, It also includes a control device, which is connected to the X-ray source, the switchable focusing device, the sample carrier, the transmission imaging detector and the fluorescence imaging detector.

3. The dual-modal X-ray imaging system according to claim 1, characterized in that, The switchable focusing device includes a displacement stage and a focusing element. The focusing element is fixed to the displacement stage by a special clamp. The displacement stage is used to move the focusing element relative to the main optical axis so that the focusing element is on or off the main optical axis. The focusing element is used to focus the X-rays into a focused spot.

4. The dual-modal X-ray imaging system according to claim 3, characterized in that, The switchable focusing device further includes a positioning baffle, a first limiting protection unit, and a second limiting protection unit. The positioning baffle is located between the displacement stage and the sample carrying device, the first limiting protection unit is located between the displacement stage and the X-ray source, and the second limiting protection unit is located between the positioning baffle and the sample carrying device.

5. The dual-modal X-ray imaging system according to claim 1, characterized in that, The sample carrying device includes a sample stage and a sample clamp. The sample is fixed on the sample stage by the sample clamp, and the sample stage is used to enable the sample to rotate and translate.

6. The dual-modal X-ray imaging system according to claim 1, characterized in that, The transmission imaging detector is an X-ray surface detector.

7. The dual-modal X-ray imaging system according to claim 1, characterized in that, The fluorescence imaging detector is an energy-dispersive single-photon counting point scanning detector.

8. The dual-modal X-ray imaging system according to claim 1, characterized in that, It also includes a protective device, in which the X-ray source, the switchable focusing device, the sample carrier, the transmission imaging detector and the fluorescence imaging detector are all located, and the protective device is used for radiation shielding.

9. A dual-modal X-ray imaging method, characterized in that, include: Provide a dual-modal X-ray imaging system as described in claim 2; The control device controls the switchable focusing device to move to a position off the main optical axis, mounts the sample on the sample carrier, and controls the sample carrier to move with the sample so that the sample moves to the main optical axis. XCT imaging was performed on the sample to obtain a three-dimensional XCT tomographic image of the sample; The region of interest of the sample is determined based on the XCT three-dimensional tomographic image of the sample, and the XFCT imaging parameters are determined based on the region of interest of the sample. The control device controls the switchable focusing device to move onto the main optical axis and performs optical path calibration; XFCT imaging is performed on the region of interest of the sample based on XFCT imaging parameters to obtain the XFCT three-dimensional tomographic image of the sample. The control device performs in-situ fusion of the XCT three-dimensional tomographic image and the XFCT three-dimensional tomographic image of the sample to obtain a dual-modal fused image of the sample.

10. The dual-modal X-ray imaging method according to claim 9, characterized in that, Optical path calibration includes: The control device controls the movement of the sample carrier, causing the sample to move and leave the main optical axis; The control device controls the X-ray conduction of the X-ray source. The X-rays are focused into a focused spot by a switchable focusing device. The focused spot is incident on the transmission imaging detector, which detects the two-dimensional grayscale image of the focused spot. The control device processes the two-dimensional grayscale image of the focused spot to obtain the centroid coordinates of the spot and the coaxial deviation between the centroid coordinates of the spot and the reference coordinates of the principal optical axis. The control device controls the switchable focusing device to make micro-translation adjustments based on the coaxial deviation between the centroid coordinates of the light spot and the reference coordinates of the principal optical axis. Each adjustment sequentially acquires a two-dimensional grayscale image of the focused light spot until the coaxial deviation between the centroid of the light spot and the reference coordinates of the principal optical axis is less than the preset value. The control device controls the X-ray to be disconnected.

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