Fluorescence diffusion tomography system with double-line simultaneous scanning excitation

Abstract

The invention discloses a fluorescence diffusion tomography system capable of scanning and exciting two lines simultaneously, and relates to the field of optical and biomedical engineering, and the system comprises a rotary objective table which is used for placing a sample and driving the sample to rotate; the laser scanning module is used for emitting double-line exciting light to scan and excite the sample, so that a fluorescent target in the sample generates fluorescent light; and the detection module is used for detecting the double-line exciting light and the fluorescent light, performing reverse image reconstruction according to the double-line exciting light and the fluorescent light, and generating a three-dimensional image of the fluorescent target in the sample. According to the method, the overall reconstruction quality of FDT imaging can be further improved while the high imaging rate is kept.

Description

Technical Field

[0001] This application relates to the fields of optics and biomedical engineering, and particularly to a fluorescence diffusion tomography system with dual-line simultaneous scanning excitation. Background Art

[0002] Fluorescence Diffusion Tomography (FDT), also known as Fluorescence Molecular Tomography (FMT), is a macroscopic optical imaging technology used in the biomedical field. FDT irradiates the surface of biological tissue with excitation light in the near-infrared band from multiple angles in sequence. After the excitation light diffuses through the tissue, it excites the fluorescent targets labeled by specific molecular probes in the tissue, thereby emitting fluorescent signals. Then, the optical signal detection device is used to collect the excitation light signals and fluorescent signals that reach the tissue surface after diffusion. Based on the light transmission model and corresponding reconstruction algorithms, three-dimensional stereoscopic reconstruction of fluorescent targets in the living body can be achieved. This technology can perform localization and quantitative imaging of fluorescent probes in small animals as a whole or specific organs of the human body, and has the characteristics of large imaging range, deep imaging depth, low cost, and no radiation. Currently, it has been widely used in fields such as early cancer diagnosis, drug development, brain function imaging, and gene therapy.

[0003] In recent years, due to its unique advantages, FDT technology has begun to be involved in the field of dynamic imaging with extremely high real-time requirements, such as surgical navigation and pharmacokinetic research. However, the traditional FDT technology relies on the point light source scanning excitation mode, and the slow imaging rate caused by this mode seriously hinders its further expansion and application in the field of dynamic imaging. To overcome this problem, a fluorescence diffusion tomography method and system with full-angle line scanning excitation have been proposed. This system uses a line light source to replace the point light source for scanning excitation, and corresponding forward process modeling and system calibration technologies have been developed. The aim is to significantly improve the FDT imaging speed without sacrificing the reconstruction accuracy. Phantom experiment data strongly confirms that the line scanning FDT system not only greatly shortens the imaging data acquisition cycle but also improves the reconstruction quality to a certain extent.

[0004] Nevertheless, both the traditional point scanning excitation mode and the single-line scanning excitation mode that has been proposed face a common problem: after excitation at many angles, the intensity of the fluorescent signals received by the opposite detection surface is weak. The weaker fluorescent signals are more vulnerable to noise interference and even completely masked, thus seriously restricting the reconstruction quality of FDT. Moreover, as the excitation angle changes, the difference in the intensity of the fluorescent signals is not significant, which also seriously restricts the reconstruction quality of FDT. Summary of the Invention

[0005] The purpose of this application is to provide a fluorescence diffuse tomography system with dual-line simultaneous scanning excitation, which can improve the overall reconstruction quality of FDT imaging.

[0006] To achieve the above object, the present application provides the following solutions.

[0007] The present application provides a fluorescence diffuse tomography system with dual-line simultaneous scanning excitation, including the following devices.

[0008] A rotating stage for placing a sample and driving the sample to rotate.

[0009] A laser scanning module for emitting dual-line excitation light to scan and excite the sample, so that fluorescent targets in the sample generate fluorescence.

[0010] A detection module for detecting the dual-line excitation light and the fluorescence, and performing inverse image reconstruction based on the dual-line excitation light and the fluorescence to generate a three-dimensional image of the fluorescent target inside the sample.

[0011] Optionally, the laser scanning module includes the following devices.

[0012] A near-infrared laser for emitting a near-infrared excitation beam.

[0013] A first lens disposed on the outgoing light path of the near-infrared laser for focusing the near-infrared excitation beam.

[0014] A small hole disposed on the transmitted light path of the first lens for filtering the focused near-infrared excitation beam.

[0015] A second lens disposed on the outgoing light path of the small hole for collimating the filtered near-infrared excitation beam.

[0016] A diaphragm disposed on the transmitted light path of the second lens for restricting the diameter of the collimated near-infrared excitation beam.

[0017] A beam shaper disposed on the outgoing light path of the diaphragm for converting the near-infrared excitation beam with a restricted diameter from a Gaussian beam into a uniform flat-top beam.

[0018] A beam splitter disposed on the outgoing light path of the beam shaper for splitting the uniform flat-top beam into two beams, namely a first beam and a second beam.

[0019] A first light path turning device disposed on the outgoing light path of the beam splitter for redirecting the first beam and focusing the redirected first beam on the surface of the sample.

[0020] The second light conversion path is arranged on the outgoing light path of the beam splitter and is used to direct the second light beam and focus the redirected second light beam on the surface of the sample; the redirected first light beam and the redirected second light beam form a two-line excitation light.

[0021] Optionally, the first conversion path includes the following devices.

[0022] The first cylindrical lens is arranged on the outgoing light path of the beam splitter and is used to focus the first light beam in the horizontal direction to form a first line light beam.

[0023] The first reflector is arranged on the transmission light path of the first cylindrical lens and is used to reflect the first line light beam.

[0024] The first two-axis galvanometer is arranged on the reflection light path of the first reflector and is used to change the direction of the reflected first line light beam to generate a redirected first light beam.

[0025] The first flat-field scanning lens is arranged on the outgoing light path of the first two-axis galvanometer and is used to focus the redirected first light beam.

[0026] Optionally, the second conversion path includes the following devices.

[0027] The second reflector is arranged on the outgoing light path of the beam splitter and is used to reflect the second light beam.

[0028] The second cylindrical lens is arranged on the reflection light path of the second reflector and is used to focus the reflected second light beam in the horizontal direction to form a second line light beam.

[0029] The second two-axis galvanometer is arranged on the transmission light path of the second cylindrical lens and is used to change the direction of the second line light beam to generate a redirected second light beam.

[0030] The second flat-field scanning lens is arranged on the outgoing light path of the second two-axis galvanometer and is used to focus the redirected second light beam.

[0031] Optionally, the included angle between the redirected first light beam and the redirected second light beam is from 0 degrees to 180 degrees, and the intersection of the redirected first light beam and the redirected second light beam is located on the rotation axis of the rotary stage.

[0032] Optionally, the included angle between the redirected first light beam and the redirected second light beam is 90 degrees, and the intersection of the redirected first light beam and the redirected second light beam is located on the rotation axis of the rotary stage.

[0033] Optionally, the laser scanning module further includes: a shutter disposed on the transmission optical path of the second lens for controlling the opening and closing of the transmission optical path.

[0034] Optionally, the detection module includes: a filter set, a camera lens, an electron multiplying charge coupled device, and a computer; the filter set, the camera lens, and the electron multiplying charge coupled device are sequentially arranged.

[0035] The double-line excitation light or the fluorescence is filtered by the filter set, and the filtered light beam is converged by the camera lens onto the electron multiplying charge coupled device, and the electron multiplying charge coupled device detects the converged light beam.

[0036] The computer is connected to the electron multiplying charge coupled device; the computer is configured to receive and store detection data, and perform inverse image reconstruction based on the detection data to generate a three-dimensional image of the fluorescence target inside the sample; the detection data includes: double-line excitation light and fluorescence.

[0037] The computer is also connected to the near-infrared laser for controlling the near-infrared laser to emit a near-infrared excitation light beam.

[0038] The computer is also respectively connected to the first biaxial galvanometer and the second biaxial galvanometer for controlling the operating voltages of the first biaxial galvanometer and the second biaxial galvanometer, and changing the beam angle according to the operating voltages.

[0039] The computer is also connected to the rotating stage for controlling the rotating stage to rotate.

[0040] Optionally, the filter set includes the following devices.

[0041] A fluorescence filter disposed on a turntable for filtering the double-line excitation light and passing the fluorescence.

[0042] An excitation light filter disposed on the turntable for filtering the fluorescence and passing the double-line excitation light.

[0043] The turntable is used to adjust the positions of the fluorescence filter and the excitation light filter.

[0044] Optionally, the fluorescence filter, the excitation light filter, and the turntable are one or more.

[0045] According to the specific embodiments provided by the present application, the present application has the following technical effects.

[0046] The present application provides a fluorescence diffusion tomography system with dual-line simultaneous scanning excitation. The rotating stage drives the sample to rotate, enabling the laser scanning module to perform multi-angle scanning excitation on the dual-line excitation light emitted by the sample, so that the fluorescent targets in the sample generate fluorescent signals with higher intensity and significant variation with the excitation angle. Furthermore, it provides better data support for subsequent FDT image reconstruction. Finally, the detection module receives the multi-angle dual-line excitation light and fluorescence to perform three-dimensional image reconstruction of the fluorescent targets inside the sample, thereby improving the overall reconstruction quality of the final FDT imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] To more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0048] Figure 1 It is a schematic structural diagram of a fluorescence diffusion tomography system with dual-line simultaneous scanning excitation provided by an embodiment of the present application.

[0049] Figure 2 It is a schematic diagram of a three-dimensional view and a sectional view of a heterogeneous cylinder simulation model provided by an embodiment of the present application; among them, (a) is the three-dimensional view of the heterogeneous cylinder simulation model, and (b) is the sectional view of the heterogeneous cylinder simulation model.

[0050] Figure 3 It is a schematic cross-sectional view of single-line and dual-line excitation modes provided by an embodiment of the present application; among them, (a) is the schematic cross-sectional view of the single-line excitation mode, and (b) is the schematic cross-sectional view of the dual-line excitation mode.

[0051] Figure 4 It is a line graph showing the variation of the maximum fluorescence intensity value of a dual-fluorophore with the excitation angle under single-line excitation and dual-line excitation with an angle of 90° provided by an embodiment of the present application.

[0052] Figure 5 It is a schematic diagram of the image reconstruction results of a dual-fluorophore under single-line and dual-line (angle 90°) scanning excitation modes provided by an embodiment of the present application; among them, (a) is the three-dimensional distribution diagram of the real fluorophore, (b) is the middle-layer sectional view of the real fluorophore, (c) is the three-dimensional distribution diagram of the fluorophore reconstructed by single-line excitation, (d) is the middle-layer sectional view of the fluorophore reconstructed by single-line excitation, (e) is the three-dimensional distribution diagram of the fluorophore reconstructed by dual-line excitation, and (f) is the middle-layer sectional view of the fluorophore reconstructed by dual-line excitation.

[0053] Reference numerals: 1 - near-infrared laser; 2 - first lens; 3 - small hole; 4 - second lens; 5 - shutter; 6 - diaphragm; 7 - beam shaper; 8 - beam splitter; 9 - first cylindrical lens; 10 - first mirror; 11 - first biaxial galvanometer; 12 - first flat-field scanning lens; 13 - second mirror; 14 - second cylindrical lens; 15 - second biaxial galvanometer; 16 - second flat-field scanning lens; 17 - rotary stage; 18 - filter set; 19 - camera lens; 20 - electron multiplying charge-coupled device; 21 - computer. Detailed implementation manners

[0054] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0055] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0056] In an exemplary embodiment, as Figure 1 shown, a fluorescence diffuse optical tomography system for simultaneous double-line scanning excitation is provided, including: a rotary stage 17, a laser scanning module, and a detection module.

[0057] The rotary stage 17 is used to place a sample and drive the sample to rotate.

[0058] The laser scanning module is used to emit double-line excitation light to scan and excite the sample, so that fluorescent targets in the sample generate fluorescence.

[0059] The detection module is used to detect the double-line excitation light and fluorescence, and perform inverse image reconstruction based on the double-line excitation light and fluorescence to generate a three-dimensional image of the fluorescent targets inside the sample.

[0060] Specifically, as Figure 1 shown, the laser scanning module includes: a near-infrared laser 1, a first lens 2, a small hole 3, a second lens 4, a diaphragm 6, a beam shaper 7, a beam splitter 8, a first conversion optical path, and a second conversion optical path.

[0061] A near-infrared laser 1, which is used to emit a near-infrared excitation beam. A multimode semiconductor laser with a wavelength of 750 nm is used as the light source. This is because the scattering and absorption of near-infrared light in tissues are relatively weak compared to visible light, which is beneficial to improving the quality of FDT imaging; a first lens 2, which is arranged on the outgoing light path of the near-infrared laser 1 and is used to focus the near-infrared excitation beam, facilitating small-hole filtering and subsequent collimation; a small hole 3, which is arranged on the transmitted light path of the first lens 2 and is used to filter the focused near-infrared excitation beam to achieve filtering of multimode laser; a second lens 4, which is arranged on the outgoing light path of the small hole 3 and is used to parallelize the filtered near-infrared excitation beam, converting the focused laser into parallel light; a diaphragm 6, which is arranged on the transmitted light path of the second lens 4 and is used to limit the diameter of the near-infrared excitation beam after parallel processing; a beam shaper 7, which is arranged on the outgoing light path of the diaphragm 6 and is used to convert the Gaussian beam in the near-infrared excitation beam with a limited diameter into a uniform flat-top beam; a beam splitter 8, which is arranged on the outgoing light path of the beam shaper 7 and is used to split the uniform flat-top beam into two beams, namely a first beam and a second beam, and the intensities of the first beam and the second beam are comparable; a first conversion optical path, which is arranged on the outgoing light path of the beam splitter and is used to direct the first beam and focus the directed first beam on the surface of the sample; a second conversion optical path, which is arranged on the outgoing light path of the beam splitter and is used to direct the second beam and focus the directed second beam on the surface of the sample; the directed first beam and the directed second beam form a two-line excitation light.

[0062] Specifically, the first conversion optical path includes: a first cylindrical lens 9, a first mirror 10, a first two-axis galvanometer 11, and a first flat-field scanning lens 12.

[0063] The first cylindrical lens 9 is arranged on the outgoing light path of the beam splitter 8 and is used to gradually focus the first beam in the horizontal direction to form a first line beam; the first mirror 10 is arranged on the transmitted light path of the first cylindrical lens 9 and is used to reflect the first line beam; the first two-axis galvanometer 11 is arranged on the reflected light path of the first mirror 10 and is used to change the direction of the reflected first line beam to generate the directed first beam, realizing two-dimensional scanning; the first flat-field scanning lens 12 is arranged on the outgoing light path of the first two-axis galvanometer 11 and is used to focus the directed first beam so that the directed first beam is focused on the surface of the sample.

[0064] Specifically, the second conversion optical path includes: a second mirror 13, a second cylindrical lens 14, a second two-axis galvanometer 15, and a second flat-field scanning lens 16.

[0065] The second reflector 13 is disposed on the outgoing light path of the beam splitter 8 and is configured to reflect the second light beam. The second cylindrical lens 14 is disposed on the reflected light path of the second reflector 13 and is configured to gradually focus the second light beam in the horizontal direction to form a second line beam. The second two-axis galvanometer 15 is disposed on the transmitted light path of the second cylindrical lens 14 and is configured to change the direction of the reflected second line beam to generate a second light beam after being redirected, thereby achieving two-dimensional scanning. The second flat-field scanning lens 16 is disposed on the outgoing light path of the second two-axis galvanometer 15 and is configured to focus the second light beam after being redirected so that the second light beam after being redirected is focused on the sample surface.

[0066] As an optional implementation manner, the laser scanning module further includes a shutter 5. The shutter 5 is disposed on the transmitted light path of the second lens 4 and is configured to control the opening and closing of the transmitted light path.

[0067] Specifically, the included angle between the first light beam after being redirected and the second light beam after being redirected is from 0 degrees to 180 degrees, and the intersection of the first light beam after being redirected and the second light beam after being redirected is located on the rotation axis of the rotary stage 17.

[0068] Specifically, the included angle between the first light beam after being redirected and the second light beam after being redirected is 90 degrees, and the intersection of the first light beam after being redirected and the second light beam after being redirected is located on the rotation axis of the rotary stage 17. As Figure 1 shown, by adjusting the placement positions of the optical devices, a certain included angle can be formed among the first light beam after being redirected, the second light beam after being redirected, and the rotation axis of the rotary stage. Figure 1 The figure shows a schematic structural diagram of a two-line scanning FDT system with a two-line included angle of 90°.

[0069] Specifically, the detection module includes: a filter set 18, a camera lens 19, an electron multiplying charge coupled device 20, and a computer 21. The filter set 18, the camera lens 19, and the electron multiplying charge coupled device 20 are arranged in sequence. The computer 21 is connected to the electron multiplying charge coupled device 20.

[0070] The double-line excitation light or fluorescence is filtered by the filter set 18. The filtered light beam is converged onto the electron multiplying charge coupled device 20 through the camera lens 19, and the electron multiplying charge coupled device 20 detects the converged light beam; the computer 21 is used to receive and store the detection data, and perform inverse image reconstruction based on the detection data to generate a three-dimensional image of the fluorescence target inside the sample; the detection data includes: double-line excitation light and fluorescence; the computer 21 is also connected to the near-infrared laser 1 and is used to control the near-infrared laser 1 to emit near-infrared laser. Among them, the camera lens 19 is used to collect the light beam and converge the collected light beam onto the electron multiplying charge coupled device 20; the converged light beam detected by the electron multiplying charge coupled device 20 is double-line excitation light or fluorescence; the computer 21 is also connected to the shutter and is used to control the opening or closing of the shutter; the computer 21 is also connected to the rotary stage 17 and is used to control the rotation of the rotary stage 17; the computer 21 is also respectively connected to the first biaxial galvanometer 11 and the second biaxial galvanometer 15 and is used to control the working voltages of the first biaxial galvanometer 11 and the second biaxial galvanometer 15, and change the light beam angle according to the working voltages to achieve the change of the light beam angle.

[0071] Specifically, the filter set 18 includes: a fluorescence filter, an excitation light filter, and a turntable.

[0072] The fluorescence filter is arranged on the turntable and is used to filter out the double-line excitation light and pass the fluorescence; the excitation light filter is arranged on the turntable and is used to filter out the fluorescence and pass the double-line excitation light. The two filters are placed at different positions on the turntable. When detecting different wavelength bands, it is necessary to adjust the corresponding filter (fluorescence filter or excitation light filter) to in front of the lens through the turntable.

[0073] Specifically, the fluorescence filter, the excitation light filter, and the turntable are one or more.

[0074] In a specific embodiment, the specific imaging steps of the fluorescence diffuse optical tomography system using the above double-line simultaneous scanning excitation are as follows.

[0075] Place the sample containing the fluorescent target on the rotating stage, turn on the near-infrared laser 1 and the shutter 5. The near-infrared light is focused after passing through the first lens 2, then filtered through the small hole 3, and forms a parallel beam after passing through the second lens 4. Then, it passes through the shutter 5, the aperture 6, and the beam shaper 7 in sequence to become a collimated, uniform parallel light. Then the beam is split into two beams of equal intensity, the first beam and the second beam, by the beam splitter 8. The first beam is focused in the horizontal direction by the cylindrical lens, reflected by the mirror and enters the biaxial galvanometer, and then after being regulated in the scanning direction by the biaxial galvanometer, passes through the flat-field scanning lens to form a line of the first beam focused on the sample surface; the second beam is focused in the horizontal direction by the cylindrical lens after passing through the mirror, and then after being regulated in the scanning direction by the biaxial galvanometer, passes through the flat-field scanning lens to form a line of the second beam focused on the sample surface. By controlling the rotation of the rotating stage 17, scanning of the sample at different angles is achieved.

[0076] After the two excitation line light sources hit the tissue surface of the sample, they will diffuse inside it. When they reach the fluorescent target, they will excite the fluorophore to generate fluorescence. Then, the fluorescence will also diffuse inside the tissue like the excitation light and reach the surface and be detected by the EMCCD. When using the EMCCD to detect fluorescence, first place the fluorescence filter in front of the lens to filter out the excitation light, and then converge the beam to the EMCCD through the camera lens 19; the operation of using the EMCCD to detect the excitation light is similar, just place the excitation light filter in front of the lens to filter out the fluorescence, and then converge the beam to the EMCCD through the camera lens 19.

[0077] Finally, combined with the dual-line scanning FDT forward model, use the detected excitation light and fluorescence data for inverse image reconstruction, so as to realize dual-line scanning fluorescence diffusion tomography, and finally obtain the three-dimensional image of the fluorescent target inside the sample.

[0078] For the forward modeling process in the dual-line scanning FDT image reconstruction, the field strength distribution in the excitation light band of the dual-line light source can be regarded as the superposition of the field strength distributions in the excitation light bands of two single-line light sources. For a single-line light source, it can be modeled as an overall composed of multiple point light sources. Then, the field strength distribution in the excitation light band diffused by the dual-line light source can be regarded as the weighted superposition of the field strength distributions in the excitation light bands diffused by multiple point light sources. Perform normalized Born approximation processing on the processed field strength distributions in the excitation band and the fluorescence band, and the dual-line scanning FDT forward system matrix A can be obtained. Further, the dual-line scanning FDT system forward model is as follows.

[0079] 。

[0080] Among them, is the ratio of the fluorescence detection data to the excitation light detection data, It is the three-dimensional distribution of fluorescence targets inside the sample to be measured. By using the above formula and combining the excitation light and fluorescence data obtained by detection, the double-line scanning FDT image reconstruction can be carried out.

[0081] In order to verify the improvement effect of the double-line scanning FDT method and system proposed in this application on the image reconstruction quality, a heterogeneous cylinder simulation experiment was designed. The heterogeneous cylinder simulation model is as Figure 2 shown, with multiple regions inside, representing different tissue structures. The optical parameters set for different tissue structures are shown in Table 1.

[0082] Table 1 Optical parameters of each tissue structure in the heterogeneous cylinder simulation model

[0083] This application set up FDT image reconstruction simulation experiments in single-line and double-line scanning excitation modes. Figure 3 In (a) and (b) of

[0084] are respectively the cross-sectional schematic diagrams of single excitation of double fluorophores and double excitation of double fluorophores. In the simulation experiment, the power of each single light source was set to be consistent; the size of the fluorophore was set to be 2 mm in length, 2 mm in width, and 6 mm in height; the angle between the double line and the rotation axis was set to 90°. Figure 4 shows the variation of the maximum fluorescence intensity value detected on the opposite detection surface after single excitation and double excitation when there are double fluorophores in the model. The solid line represents double excitation with an angle of 90°, and the dotted line represents single excitation. From Figure 4 it can be seen that the fluorescence signal intensity detected by single excitation is weak, and the intensity difference with the change of the excitation angle is not obvious, which will make the FDT reconstruction sensitive to noise and limit the image reconstruction quality. For the double-line simultaneous excitation mode, the detected fluorescence signal intensity is significantly enhanced, and the intensity difference degree with the change of the excitation angle is also relatively obvious.

[0085] Next, FDT simulation reconstruction was carried out in single-line and double-line scanning excitation modes. The length of each line light source in the experiment was also set to 10 mm, which was evenly divided into 20 point light sources. The detector selection range was all sample surface nodes within the z-axis range [-12, 12] within 150° on the other side directly opposite the light source, and half of them were selected as detectors in a pattern of selecting every other point. The reconstruction regularization method used the iteratively reweighted L1 regularization method (IRL1), and the optimization method selected the split Bregman algorithm. The specific parameter settings for the simulation reconstruction experiment are shown in Table 2.

[0086] Table 2 Parameter settings for the simulation reconstruction experiment

[0087] Table 3 shows the simulation reconstruction quantitative indicators of the dual fluorophore in two scanning excitation modes. Among them, RMSE represents the root mean square error, CNR represents the contrast signal-to-noise ratio, Dice is the similarity metric coefficient, and LE represents the localization error. When the RSME and LE are smaller and the CNR and Dice are larger, the FDT image reconstruction quality is better. Figure 5 are the image reconstruction results of the dual fluorophore in single-line and double-line (90° angle) scanning excitation modes, Figure 5 where (a) and (b) in are the three-dimensional distribution map and the middle layer slice map of the real fluorophore, Figure 5 where (c) and (d) in are the three-dimensional distribution map and the middle layer slice map of the fluorophore reconstructed by single-line excitation, Figure 5 where (e) and (f) in are the three-dimensional distribution map and the middle layer slice map of the fluorophore reconstructed by double-line excitation.

[0088] Table 3 Simulation reconstruction quantitative indicators of the dual fluorophore in single-line and double-line excitation scanning modes

[0089] It can be seen from the results in Table 3 that when the angle between the two lines is 90°, the FDT image reconstruction index of the double-line simultaneous excitation scanning mode has been significantly improved compared with that of single-line excitation. From Figure 5It can be seen that there are many artifacts in the reconstructed image of the single-line scanning FDT, and it is difficult to reconstruct the square cross-sectional morphology of the fluorophore. However, there are fewer artifacts in the reconstructed image of the double-line scanning FDT when the included angle between the two lines is 90°, and the cross-sectional morphology of the fluorophore is well reconstructed. The simulation experiment verifies that the double-line scanning FDT system can further improve the FDT image reconstruction quality while retaining the high imaging rate of the line scanning excitation mode. It should be noted that different imaging samples and different fluorophore distribution situations may correspond to different optimal double-line excitation included angles, and the optimal excitation mode that can meet all situations cannot be satisfied. Therefore, a relatively moderate double-line included angle, such as 90°, can be selected when building the double-line scanning FDT system.

[0090] Aiming at the problem that the fluorescence detection intensity of the previously proposed single-line scanning FDT system is weak and the difference with the change of the excitation angle is not obvious, which restricts the image reconstruction quality, this application further improves the excitation mode and innovatively proposes a double-line scanning FDT system, which can further improve the FDT image reconstruction quality while retaining the high imaging rate of the line scanning excitation mode. This application has the following beneficial effects.

[0091] For the double-line scanning FDT system proposed in this application, each excitation uses a double-line light source at a certain included angle with the rotation axis to simultaneously excite the sample to be measured, and the excitation light signal and fluorescence signal diffused to the sample surface are detected on the opposite side. The rotation stage drives the sample to be measured to rotate, so as to realize full-angle scanning excitation and detection. After that, the acquisition of FDT imaging data is completed, which can be used for subsequent FDT image reconstruction. This double-line scanning FDT system can further enhance the intensity of the detected fluorescence signal and the degree of difference with the change of the excitation angle while retaining the high imaging rate of the line scanning excitation mode. Combined with the corresponding forward process modeling method of double-line FDT, this fluorescence diffusion tomography system with double-line simultaneous scanning excitation can significantly improve the image reconstruction quality.

[0092] For the forward process modeling method of double-line scanning FDT image reconstruction, the field strength distribution of the excitation light band of the double-line light source is modeled as the superposition of the field strength distributions of the excitation light bands of two single-line light sources. And a single line light source can be discretized into multiple point light sources, then the field strength distribution of the excitation light band diffused by each line light source in the tissue can be regarded as the weighted sum of the field strength distributions of the excitation light bands of the point light sources. This method can more accurately describe the diffusion movement of the double-line light source in the sample and ensure the accuracy of forward modeling and inverse reconstruction.

[0093] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0094] In this article, specific examples are used to illustrate the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A fluorescence diffuse optical tomography system with dual-line simultaneous scanning excitation, characterized in that, The fluorescence diffuse tomography system with dual-line simultaneous scanning excitation includes: A rotating stage for placing the sample and driving the sample to rotate; A laser scanning module for emitting dual-line excitation light to scan and excite the sample, causing fluorescent targets in the sample to generate fluorescence; A detection module for detecting the dual-line excitation light and the fluorescence, and performing inverse image reconstruction based on the dual-line excitation light and the fluorescence to generate a three-dimensional image of the fluorescent targets inside the sample.

2. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 1, characterized in that The laser scanning module includes: A near-infrared laser for emitting a near-infrared excitation beam; A first lens disposed on the output light path of the near-infrared laser for focusing the near-infrared excitation beam; A small hole disposed on the transmitted light path of the first lens for filtering the focused near-infrared excitation beam; A second lens disposed on the output light path of the small hole for collimating the filtered near-infrared excitation beam; A diaphragm disposed on the transmitted light path of the second lens for restricting the diameter of the collimated near-infrared excitation beam; A beam shaper disposed on the output light path of the diaphragm for converting the near-infrared excitation beam with restricted diameter from a Gaussian beam into a uniform flat-top beam; A beam splitter disposed on the output light path of the beam shaper for splitting the uniform flat-top beam into two beams, namely a first beam and a second beam; A first conversion optical path disposed on the output light path of the beam splitter for redirecting the first beam and focusing the redirected first beam on the surface of the sample; A second conversion optical path disposed on the output light path of the beam splitter for redirecting the second beam and focusing the redirected second beam on the surface of the sample; the redirected first beam and the redirected second beam form the dual-line excitation light.

3. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 2, wherein The first conversion optical path includes: A first cylindrical lens disposed on the output light path of the beam splitter for focusing the first beam in the horizontal direction to form a first line beam; A first mirror disposed on the transmitted light path of the first cylindrical lens for reflecting the first line beam; A first two-axis galvanometer disposed on the reflected light path of the first mirror for changing the direction of the reflected first line beam to generate the redirected first beam; A first flat-field scanning lens disposed on the output light path of the first two-axis galvanometer for focusing the redirected first beam.

4. The fluorescence diffuse tomography system with dual-line simultaneous scanning excitation according to claim 3, wherein The second conversion optical path includes: A second mirror disposed on the output light path of the beam splitter for reflecting the second beam; A second cylindrical lens disposed on the reflected light path of the second mirror for focusing the reflected second beam in the horizontal direction to form a second line beam; A second two-axis galvanometer disposed on the transmitted light path of the second cylindrical lens for changing the direction of the second line beam to generate the redirected second beam; A second flat-field scanning lens disposed on the output light path of the second two-axis galvanometer for focusing the redirected second beam.

5. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 4, wherein The included angle between the first beam after adjustment and the second beam after adjustment is from 0 degree to 180 degrees, and the intersection of the first beam after adjustment and the second beam after adjustment is located on the rotation axis of the rotating stage.

6. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 4, wherein The included angle between the first beam after adjustment and the second beam after adjustment is 90 degrees, and the intersection of the first beam after adjustment and the second beam after adjustment is located on the rotation axis of the rotating stage.

7. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 2, wherein The laser scanning module further includes: a shutter, disposed on the transmission optical path of the second lens, for controlling the opening and closing of the transmission optical path.

8. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 4, wherein The detection module includes: a filter set, a camera lens, an electron multiplying charge coupled device, and a computer; the filter set, the camera lens, and the electron multiplying charge coupled device are arranged in sequence; The double-line excitation light or the fluorescence is filtered by the filter set, and the filtered light beam is converged by the camera lens onto the electron multiplying charge coupled device, and the electron multiplying charge coupled device detects the converged light beam; The computer is connected to the electron multiplying charge coupled device; the computer is configured to receive and store detection data, and perform inverse image reconstruction based on the detection data to generate a three-dimensional image of the fluorescence target inside the sample; the detection data includes: double-line excitation light and fluorescence; The computer is further connected to the near-infrared laser, and is used to control the near-infrared laser to emit a near-infrared excitation beam; The computer is also respectively connected to the first biaxial galvanometer and the second biaxial galvanometer, and is used to control the operating voltages of the first biaxial galvanometer and the second biaxial galvanometer, and change the beam angle according to the operating voltages; The computer is also connected to the rotating stage, and is used to control the rotation of the rotating stage.

9. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 8, characterized in that, The filter set includes: a fluorescence filter, disposed on a turntable, for filtering the double-line excitation light and passing the fluorescence; an excitation light filter, disposed on the turntable, for filtering the fluorescence and passing the double-line excitation light; The turntable is used to adjust the positions of the fluorescence filter and the excitation light filter.

10. The fluorescence diffuse tomography imaging system with dual-line simultaneous scanning excitation according to claim 9, characterized in that, The fluorescence filter, the excitation light filter, and the turntable are one or more.

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