Energy spectrum CT and optical dual-mode imaging system and method with high space and spectral domain resolution

Abstract

The invention discloses an energy spectrum CT and optical dual-mode imaging system and method with high space and spectral domain resolution. An X-ray energy spectrum detector in the system is used for collecting multi-energy-level X-ray projection data; the hyperspectral camera is used for collecting multispectral fluorescence data and fluorescence images; the method comprises the following steps: correcting X-ray projection under each energy level, performing three-dimensional reconstruction on corrected multi-energy-level projection data, performing volume rendering on the reconstructed three-dimensional data to obtain a three-dimensional contour of an object, mapping fluorescence data to the three-dimensional contour, and mapping the fluorescence data to the three-dimensional contour, according to an accurate substance decomposition result obtained through multi-energy-level CT reconstruction, an accurate photon transmission forward model is constructed and reconstructed by referring to scattering coefficients and absorption coefficients of different substances on the basis of a third-order simplified spherical harmonic equation, three-dimensional registration and image fusion are carried out on a dual-mode image, and a dual-mode fusion image is obtained; the dual-mode fusion image obtained by the method is high in spatial resolution and high in spectral domain resolution.

Description

Technical Field

[0001] The present invention relates to the field of medical imaging technology, and in particular to a high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging system and method. Background Art

[0002] Medical imaging technology can be divided into two categories: one is structural imaging technology represented by CT, which can obtain anatomical information of the imaging object; the other is functional imaging technology represented by PET, SPECT and optical imaging, which can obtain biochemical function information. Each imaging modality has its unique advantages and inherent shortcomings. Clearer and faster observation of changes in the physiological structure and biochemical function of the imaging object is an urgent need in current medical imaging research. High resolution and multimodality are the mainstream development directions of medical imaging technology. Among them, CT and optical dual-mode imaging have significant advantages such as high spatial resolution, stable optical probe properties, and easy use and maintenance. They have been widely used in medical imaging, especially in the field of small animal imaging.

[0003] However, the CT and optical dual-mode imaging technology in the prior art has low contrast of soft tissue imaging due to the weak CT energy spectrum and spectral resolution, and the image reconstruction of the optical and CT modes is independent of each other, and the information of the two modes cannot be effectively utilized, and the spatial resolution needs to be improved. In view of the problem that the current CT and optical dual-mode imaging energy spectrum and spectral resolution are low, and the dual-mode system is difficult to coordinate and reconstruct, resulting in low spatial resolution, the present invention proposes a high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging method. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems in the prior art and to provide a high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging system and method, so that the obtained dual-mode fusion image has high spatial resolution and high spectral resolution.

[0005] The present invention also provides a high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging method, comprising:

[0006] Collect multi-spectral fluorescence data and fluorescence images;

[0007] Collect multi-energy level X-ray projection data;

[0008] Multi-energy-level CT reconstruction: The X-ray projection at each energy level is corrected, and the corrected multi-energy-level projection data is reconstructed in three dimensions using a method based on tensor dictionary learning to obtain CT images at different energy levels;

[0009] Perform volume rendering on the three-dimensional data of the reconstructed CT image to obtain the three-dimensional contour of the object; perform angle registration on the acquired two-dimensional fluorescence image and the three-dimensional contour, and map the fluorescence data onto the three-dimensional contour;

[0010] For each spectral segment, according to the precise material decomposition results obtained by multi-level CT reconstruction, referring to the scattering coefficients and absorption coefficients of different materials, based on the third-order simplified spherical harmonic equation, an accurate photon transmission forward model is constructed, and the relationship between the three-dimensional distribution of the X-ray luminescent probe in the imaging object and the photon distribution on the surface of the imaging object is established, and an optical three-dimensional image is obtained through the reconstruction algorithm;

[0011] According to the relative position geometric relationship between the devices of the energy spectrum CT and optical dual-mode imaging system, including geometric relationships such as geometric height and angle, the dual-mode images are three-dimensionally registered based on mutual information; and a fusion method based on wavelet transform is used to perform image fusion to obtain a dual-mode fusion image.

[0012] As a preferred method, when collecting multi-spectral fluorescence data and fluorescence images, turn on the X-ray source, set parameters, use the excitation source to excite the luminescent probe in the imaging object to emit fluorescence in a specific spectral band, turn on the hyperspectral camera, and collect fluorescence images of multiple spectral bands; the rotating stage rotates through a certain angle, and continues to complete the multi-spectral fluorescence image collection until the rotating stage completes a 360-degree rotation.

[0013] As a preferred method, when collecting multi-energy level X-ray projection data, the X-ray source is kept turned on, and the X-ray transmission projection data of each energy level in the multiple energy levels are collected and saved; the rotating table rotates through a certain angle, and the multi-energy level X-ray projection data collection is continued until the rotating table completes a 360-degree rotation;

[0014] The imaging object is removed, and several X-ray projections are collected at the aforementioned energy levels, and the averaged images are used as bright-field images; the X-ray source is turned off, and several X-ray projections are collected at the aforementioned energy levels, and the averaged images are used as dark-field images.

[0015] As a preferred method, during multi-energy level CT reconstruction, bright field and dark field corrections are performed on the X-ray projections at each energy level to obtain a transformed image that can be used for reconstruction, that is, Among them I new , I are the images before and after correction respectively, I1 is the bright field image and I0 is the dark field image.

[0016] As a preferred method, the constructed forward photon transmission model is b=AS; where b is the photon distribution on the imaging object surface, S is the three-dimensional distribution of the probe, and A is the system matrix. The regularization method is used to solve it. Where S is a regular matrix, P represents different norms, and λ is a regularization parameter; L is constructed as follows:

[0017]

[0018]

[0019] in is the normalization factor, di,j is the Euclidean distance between voxel points, R is the Gaussian kernel function, Sk represents the kth component in the imaged object, i represents the row of the regular matrix L, and j represents the column of the regular matrix L.

[0020] The present invention also provides a high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging system, comprising:

[0021] An X-ray source, used for emitting X-rays and passing through an imaging object to form transmission X-rays;

[0022] A rotating table, used for carrying an imaging object and rotating the imaging object;

[0023] An X-ray luminescent probe is placed in the imaging object during imaging and emits visible or near-infrared photons under the stimulation of X-rays;

[0024] An X-ray energy spectrum detector is used to receive X-rays of different energy levels passing through the imaging object and collect multi-energy level X-ray projection data;

[0025] Hyperspectral camera, used to collect multi-spectral fluorescence data and fluorescence images;

[0026] The computer is connected to the X-ray source, the rotating stage, the X-ray energy spectrum detector and the hyperspectral camera signal, and is used to control the operation and parameter setting of the above-mentioned equipment, control the collection of optical data and X-ray projection data, process and reconstruct multi-spectral fluorescence data and multi-energy level X-ray projection data, fuse dual-modal imaging and display dual-modal fusion images.

[0027] The present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging method described in any one of the above items is implemented.

[0028] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the above-mentioned high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging method.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] Based on the spatial resolution of imaging objects brought by spectral CT, especially the high soft tissue resolution, the present invention accurately decomposes the various structures or components of the imaging object to provide support for the accurate construction of the optical imaging model. In addition, the optical three-dimensional reconstruction proposed by the present invention introduces different structures or components obtained by CT reconstruction into the regularization matrix, which helps to improve the spatial resolution of optical reconstruction, especially the morphological resolution capability.

[0031] In the high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging system of the present invention, an excitation source is used to excite the luminescent probe in the imaging object to emit fluorescence in a specific spectral band, and a hyperspectral camera is used to collect multi-spectral fluorescence data and fluorescence images, and an X-ray energy spectrum detector collects multi-energy level X-ray projection data, while conventional CT detectors cannot distinguish between X-rays of different energies; the hyperspectral camera of the present invention collects fluorescence images of multiple specific spectral bands. Compared with the method of adding filters in front of the optical camera to obtain light in different spectral bands, the system formed by the data in this method is more concise and the imaging is more efficient. The data acquisition system with spectral resolution capability of the present invention provides a data basis for improving the spatial resolution of images. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of a spectral CT and optical dual-mode imaging system with high spatial and spectral resolution according to an embodiment of the present invention.

[0033] Description of reference numerals:

[0034] 1. X-ray source, 2. Imaging object, 3. Rotating stage, 4. X-ray luminescence probe, 5. X-ray energy spectrum detector, 6. Hyperspectral camera, 7. Computer. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0036] Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with ordinary skills in the field to which the present disclosure belongs. "First", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of "including" or "comprising" cover the elements or objects listed after "including" or "comprising" and their equivalents, and do not exclude other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] The high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging system of this embodiment includes:

[0038] An X-ray source 1, used for emitting X-rays and passing through an imaging object to form transmission X-rays;

[0039] A rotating table 3, used for carrying the imaging object 2 and rotating the imaging object 2;

[0040] An X-ray luminescent probe 4 is used to be placed in the imaging object during imaging and emit visible or near-infrared photons under the stimulation of X-rays;

[0041] An X-ray energy spectrum detector 5, used to receive X-rays of different energy levels passing through the imaging object and collect multi-energy level X-ray projection data;

[0042] A hyperspectral camera 6, used for collecting multi-spectral fluorescence data and fluorescence images;

[0043] The computer 7 is connected to the X-ray source 1, the rotating table 3, the X-ray energy spectrum detector 5 and the hyperspectral camera 6 by signals, and is used to control the operation and parameter setting of the above-mentioned devices, control the collection of optical data and X-ray projection data, process and reconstruct multi-spectral fluorescence data and multi-energy level X-ray projection data, fuse dual-modal imaging and display dual-modal fused images.

[0044] This embodiment also provides an imaging method of the above-mentioned high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging system, including:

[0045] Step 1, multi-spectral fluorescence data acquisition: turn on the X-ray source, set the current, voltage and other parameters, use the excitation source to excite the luminescent probe in the imaging object to emit fluorescence in a specific spectral band, such as 610nm-1100nm, turn on the hyperspectral camera, set the relevant parameters, collect and save fluorescence images of multiple spectral bands, for example, collect spectral bands from 1000nm to 1100nm, and collect one image every 50nm. The rotating table rotates a certain angle. For example, the rotation angle of the rotating table can be 25 degrees, 30 degrees or 35 degrees each time, and the multi-spectral fluorescence image acquisition is continued until the rotating table completes a 360-degree rotation. In this embodiment, the multi-spectral fluorescence emitted by the X-ray luminescent probe after the interaction with the ray is collected for subsequent three-dimensional reconstruction.

[0046] Step 2, multi-energy level X-ray projection data acquisition: keep the X-ray source turned on, set the integration time and other parameters of the X-ray energy spectrum detector, collect multiple energy levels, such as 50kV-100kV, collect an X-ray transmission projection data every 10kV and save it. The rotating table rotates a certain angle. For example, the rotating angle of the rotating table is 1 degree each time, and the multi-energy level X-ray projection data acquisition is continued until the rotating table completes a 360-degree rotation. Remove the imaging object, collect several (such as 200) X-ray projections at the aforementioned energy levels, and average them as the bright field image I1. Turn off the X-ray source, collect several (such as 200) X-ray projections at the aforementioned energy levels, and average them as the dark field image I0.

[0047] The purpose of multi-energy-level X-ray projection data acquisition in this embodiment is to be used for correction and reconstruction of X-ray projection data at multiple energy levels.

[0048] Step 3: Multi-energy level CT reconstruction: Perform bright field and dark field correction on the X-ray projection at each energy level to obtain a transformed image that can be used for reconstruction, that is, I new and I are the images after correction and before correction, respectively. The corrected multi-energy-level projection data is subjected to three-dimensional reconstruction using a method based on tensor dictionary learning to obtain CT images of different energy levels. This embodiment obtains the three-dimensional structure and various material components of the imaging object through multi-energy-level CT reconstruction, providing a basis for subsequent optical reconstruction.

[0049] Step 4: Fluorescence data mapping: Volume rendering is performed on the object 3D data reconstructed in step 3 to obtain the 3D contour of the object. According to the geometric relationship between the imaging components, the 2D fluorescence image is angularly registered with the 3D contour, and the fluorescence data is mapped onto the 3D contour.

[0050] Step 4: Fluorescence three-dimensional reconstruction: For each spectral segment, according to the precise material decomposition results obtained by multi-level CT reconstruction, referring to the scattering coefficients and absorption coefficients of different materials, based on the third-order simplified spherical harmonic equation, an accurate forward photon transmission model is constructed, that is, b = AS. Where b is the photon distribution on the surface of the imaging object, S is the three-dimensional distribution of the probe, and A is the system matrix, which establishes the relationship between the three-dimensional distribution of the luminescent probe in the imaging object and the photon distribution on the surface of the imaging object. The regularization method is used to solve, that is, Where S is a regular matrix, P represents different norms, and λ is a regularization parameter. L is constructed as follows,

[0051]

[0052]

[0053] in is a normalization factor, di,j is the Euclidean distance between voxel points, R is a Gaussian kernel function, Sk represents the kth component in the imaging object, i represents the row of the regular matrix L, and j represents the column of the regular matrix L. In this embodiment, the reconstruction results of each spectral segment are obtained by fluorescence three-dimensional reconstruction.

[0054] Step 5: Dual-mode image registration and fusion: According to the relative position geometric relationship between the devices of the spectral CT and optical dual-mode imaging system, such as geometric height and angle, the dual-mode images are three-dimensionally registered. The image fusion method based on wavelet transform is used to obtain the dual-mode fusion image.

[0055] In the energy spectrum CT and optical dual-mode imaging system of this embodiment, an excitation source is used to excite the luminescent probe in the imaging object to emit fluorescence in a specific spectrum, and a hyperspectral camera is used to collect multi-spectral fluorescence data and fluorescence images, and an X-ray energy spectrum detector collects multi-level X-ray projection data, while a conventional CT detector cannot distinguish between X-rays of different energies; the hyperspectral camera of this embodiment collects fluorescence images of multiple specific spectrums. Compared with the method of adding filters in front of the optical camera to obtain light in different spectrums, the system formed by this method is more concise and the imaging is more efficient. The data acquisition with spectral domain resolution capability in this embodiment provides a data basis for improving the spatial resolution of the image. Based on the spatial resolution of the imaging object brought by energy spectrum CT, especially the high soft tissue resolution, this embodiment accurately decomposes the various structures or components of the imaging object, and provides support for the accurate construction of the optical imaging model. In addition, the optical three-dimensional reconstruction proposed in this embodiment introduces different mechanisms or components obtained by CT reconstruction into the regularization matrix, which helps to improve the spatial resolution of optical reconstruction, especially the morphological resolution capability. Energy spectrum CT and optical dual-mode imaging with high spatial resolution and high spectral domain resolution can be achieved.

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high spatial and spectral resolution spectral CT and optical dual-mode imaging method, characterized in that: include: Collect multi-spectral fluorescence data and fluorescence images; Collect multi-energy level X-ray projection data; Multi-energy-level CT reconstruction: The X-ray projection at each energy level is corrected, and the corrected multi-energy-level X-ray projection data is reconstructed in three dimensions using a method based on tensor dictionary learning to obtain CT images at different energy levels; Perform volume rendering on the three-dimensional data of the reconstructed CT image to obtain the three-dimensional contour of the object; perform angle registration on the acquired two-dimensional fluorescence image and the three-dimensional contour, and map the fluorescence data onto the three-dimensional contour; For each spectral segment, according to the precise material decomposition results obtained by multi-level CT reconstruction, referring to the scattering coefficients and absorption coefficients of different materials, based on the third-order simplified spherical harmonic equation, an accurate photon transmission forward model is constructed, and the relationship between the three-dimensional distribution of the X-ray luminescent probe in the imaging object and the photon distribution on the surface of the imaging object is established, and an optical three-dimensional image is obtained through the reconstruction algorithm; According to the relative position geometric relationship between the devices of the energy spectrum CT and optical dual-mode imaging system, the dual-mode images are three-dimensionally registered based on mutual information; and a fusion method based on wavelet transform is used to perform image fusion to obtain a dual-mode fusion image.

2. The high spatial and spectral resolution spectral CT and optical dual-mode imaging method according to claim 1, characterized in that: When collecting multi-spectral fluorescence data and fluorescence images, turn on the X-ray source, set parameters, use the excitation source to excite the luminescent probe in the imaging object to make it emit fluorescence in a specific spectral band, turn on the hyperspectral camera, and collect fluorescence images in multiple spectral bands; the rotating stage rotates to a certain angle and continues to complete the multi-spectral fluorescence image collection until the rotating stage completes a 360-degree rotation.

3. The high spatial and spectral resolution spectral CT and optical dual-mode imaging method according to claim 1, characterized in that: When collecting multi-energy level X-ray projection data, keep the X-ray source turned on, collect and save the X-ray transmission projection data of each energy level in multiple energy levels; when the rotating table rotates to a certain angle, continue to complete the multi-energy level X-ray projection data collection until the rotating table completes a 360-degree rotation; The imaging object is removed, and several X-ray projections are collected at the aforementioned energy levels, and the averaged images are used as bright field images; Turn off the X-ray source, collect several X-ray projections at the aforementioned energy levels, and average them as dark field images.

4. The high spatial and spectral resolution spectral CT and optical dual-mode imaging method according to claim 1, characterized in that: When CT images of different energy levels are obtained, the X-ray projection at each energy level is corrected for bright field and dark field to obtain the transformed image for reconstruction, that is, Among them I new , I are the images before and after correction respectively, I1 is the bright field image and I0 is the dark field image.

5. The high spatial and spectral resolution spectral CT and optical dual-mode imaging method according to claim 1, characterized in that: The constructed forward model of photon transmission is b=AS, where b is the photon distribution on the surface of the imaging object, S is the three-dimensional distribution of the probe, and A is the system matrix. The regularization method is used to solve it. Where S is a regular matrix, P represents different norms, and λ is a regularization parameter; L is constructed as follows: in is the normalization factor, d i,j is the Euclidean distance between voxel points, R is the Gaussian kernel function, S k represents the kth component in the imaging object, i represents the row of the regular matrix L, and j represents the column of the regular matrix L.

6. A high spatial and spectral resolution spectral CT and optical dual-mode imaging system, characterized in that: include: An X-ray source, used for emitting X-rays and passing through an imaging object to form transmission X-rays; A rotating table, used for carrying an imaging object and rotating the imaging object; An X-ray luminescent probe is placed in the imaging object during imaging and emits visible or near-infrared photons under the stimulation of X-rays; An X-ray energy spectrum detector is used to receive X-rays of different energy levels passing through the imaging object and collect multi-energy level X-ray projection data; Hyperspectral camera, used to collect multi-spectral fluorescence data and fluorescence images; The computer is connected to the X-ray source, the rotating stage, the X-ray energy spectrum detector and the hyperspectral camera signal, and is used to control the operation and parameter setting of the above-mentioned equipment, control the collection of optical data and X-ray projection data, process and reconstruct multi-spectral fluorescence data and multi-energy level X-ray projection data, fuse dual-modal imaging and display dual-modal fusion images.

7. A computer device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the energy spectrum CT and optical dual-mode imaging method with high spatial and spectral resolution as described in any one of claims 2 to 5 is implemented.

8. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the high spatial and spectral resolution energy spectrum CT and optical dual-mode imaging method according to any one of claims 2 to 5 is implemented.

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