Photoacoustic imaging system and photoacoustic imaging method

Abstract

The invention relates to a photoacoustic imaging system and a photoacoustic imaging method. The photoacoustic imaging system comprises a laser source module used for providing excitation laser; the light transmission module is connected with the laser source module and is used for combining and / or splitting the excitation laser to form a first laser beam and a second laser beam; the imaging module comprises an optical resolution module used for focusing and irradiating a first laser beam on a to-be-measured object; the acoustic resolution module is used for diverging and irradiating the second laser beam on the to-be-detected object; the ultrasonic transducer is used for detecting a photoacoustic signal generated after the to-be-detected object is excited by the first laser beam and / or the second laser beam, and converting the photoacoustic signal into an imaging signal; wherein the focus of the optical resolution module, the central point of the irradiation area of the acoustic resolution module and the detection axis of the ultrasonic transducer are arranged in an overlapping manner; the driving module is used for driving the imaging module and the to-be-detected object to move relatively; and the data processing and control module is used for performing image reconstruction based on the imaging signal.

Description

Technical Field

[0001] This application relates to the field of photoacoustic imaging technology, and in particular to photoacoustic imaging systems and methods. Background Technology

[0002] Photoacoustic imaging (PAI) is a novel biomedical imaging technique that combines the advantages of optical absorption contrast and ultrasonic detection depth. Its basic principle is that when biological tissue is irradiated with a short-pulse laser, the tissue absorbs the light energy and expands due to thermoelasticity, generating ultrasonic waves (i.e., photoacoustic signals). These signals are then received by an ultrasonic transducer and used to reconstruct the image. Photoacoustic microscopy (PAM), as an important branch of PAI, can provide high-resolution information on microvessels and tissue morphology, and has significant application value in dermatology, oncology, neuroscience, and other fields.

[0003] Optical resolution photoacoustic imaging (OR-PAM) and acoustic resolution photoacoustic imaging (AR-PAM) are two main methods of photoacoustic imaging technology. OR-PAM can achieve ultra-high spatial resolution at the micrometer level, but its imaging depth is limited by the optical diffusion limit, making it suitable for observing surface cells and microvascular structures. AR-PAM, on the other hand, although has lower resolution, can achieve tissue imaging at the centimeter level, making it more suitable for detecting large organs or deep lesions.

[0004] However, in related technologies, photoacoustic imaging systems are limited to a single imaging modality (pure OR-PAM or pure AR-PAM), and cannot simultaneously achieve high-penetration mesoscopic resolution imaging of centimeter-level deep tissues and millimeter-level shallow microscopic resolution. Summary of the Invention

[0005] Therefore, it is necessary to provide a photoacoustic imaging system and method to address the issue of how to achieve both high-penetration mesoscopic resolution imaging of centimeter-level deep tissues and millimeter-level shallow microscopic resolution.

[0006] In a first aspect, this application provides a photoacoustic imaging system, comprising:

[0007] A laser source module, wherein the laser source module is used to provide excitation laser with multiple wavelengths, multiple pulse frequencies and multiple energy ranges;

[0008] An optical transmission module is connected to a laser source module. The optical transmission module is used to transmit excitation laser and combine and / or split the excitation laser into a first laser beam and a second laser beam.

[0009] An imaging module, wherein the imaging module is configured to be positioned relative to the object under test, the imaging module comprising:

[0010] An optical resolution module is connected to the optical transmission module, and the optical resolution module is used to focus the first laser beam onto the object under test.

[0011] An acoustic resolution module is connected to the optical transmission module, and the acoustic resolution module is used to diffuse the second laser beam and irradiate the object under test.

[0012] An ultrasonic transducer is used to detect the photoacoustic signal generated by the object under test after being excited by the first laser beam and / or the second laser beam, and to convert the photoacoustic signal into an imaging signal.

[0013] The optical resolution module focuses the focal point of the first laser beam, and the center point of the irradiation area of ​​the acoustic resolution module that diverges the second laser beam is set to coincide with the detection axis of the ultrasonic transducer that detects the photoacoustic signal.

[0014] A driving module, which is used to drive the imaging module to move relative to the object under test;

[0015] The data processing and control module is communicatively connected to the laser source module, the ultrasonic transducer, and the drive module. The data processing and control module is used to control the operation of the laser source module, the ultrasonic transducer, and the drive module, and to perform image reconstruction based on the imaging signal.

[0016] The technical solution will be further explained below:

[0017] In one embodiment, the laser source module includes multiple lasers, each laser being used to emit excitation lasers with different wavelengths, different pulse frequencies, and / or different energy ranges.

[0018] In one embodiment, the optical transmission module includes:

[0019] A laser beam combining module is connected to the laser source module. The laser beam combining module is used to combine and / or split the excitation lasers emitted by different lasers to form the first laser beam and the second laser beam.

[0020] A first optical fiber, one end of which is connected to the laser beam combining module via a first optical fiber coupler, and the other end of which is connected to the optical resolution module, the first optical fiber being used to transmit the first laser beam to the optical resolution module;

[0021] The second optical fiber has one end connected to the laser beam combining module via a second optical fiber coupler, and the other end connected to the acoustic resolution module. The second optical fiber is used to transmit the second laser beam to the acoustic resolution module.

[0022] In one embodiment, the laser beam combining module includes:

[0023] Multiple first beam splitters are provided, each corresponding to one of the lasers. All the first beam splitters are used to couple a first wavelength laser suitable for the optical resolution module into the first optical fiber to form the first laser beam.

[0024] Multiple second beam splitters are provided, each corresponding to one of the lasers. All the second beam splitters are used to couple a second wavelength laser suitable for the acoustic resolution module into the second optical fiber to form the second laser beam.

[0025] In one embodiment, the optical resolution module includes:

[0026] A laser collimator is connected to the optical transmission module and is used to receive the first laser beam;

[0027] A first reflecting mirror is arranged in the optical path of the first laser beam emitted from the laser collimator, and the first reflecting mirror is used to reflect the first laser beam.

[0028] A focusing lens is arranged in the optical path of the first laser beam reflected by the first reflecting mirror, and the focusing lens is used to focus the first laser beam;

[0029] An optical-acoustic beam combining module is disposed between the object under test and the ultrasonic transducer. The optical-acoustic beam combining module is used to guide the first laser beam focused by the focusing lens to be incident on the object under test, and to make the incident optical path of the first laser beam on the object under test coaxial with the detection axis of the ultrasonic transducer. The optical-acoustic beam combining module can be penetrated by the optical-acoustic signal.

[0030] In one embodiment, the photoacoustic beam combining module includes a plurality of second reflectors arranged sequentially opposite each other, the plurality of second reflectors being used to sequentially reflect the first laser beam to guide the first laser beam to be incident on the object under test at an angle coaxial with the detection axis of the ultrasonic transducer.

[0031] In one embodiment, the acoustic resolution module includes a plurality of laser diverging elements, all of which are connected to the optical transmission module. The laser diverging elements are used to irradiate the second laser beam onto the object under test. The plurality of laser diverging elements are arranged at intervals along the outer periphery of the ultrasonic transducer, and the laser diverging elements are tilted relative to the detection axis of the ultrasonic transducer so that the center point of the irradiation area formed by all the laser diverging elements on the object under test coincides with the detection axis of the ultrasonic transducer.

[0032] In one embodiment, the imaging module further includes a first mounting base, which has an annular structure and is disposed between the ultrasonic transducer and the object under test. The first mounting base is provided with a through hole for avoiding the first laser beam and the photoacoustic signal. A plurality of first mounting holes are provided at intervals along the circumference of the first mounting base, and the laser emitting element is installed in the first mounting hole in a corresponding manner.

[0033] In one embodiment, the imaging module further includes a second mounting base;

[0034] The second mounting base is connected to the drive module, and the first mounting base is connected to the end of the second mounting base closer to the object under test;

[0035] The second mounting base has a second mounting hole, which extends through to the end of the second mounting base near the object to be tested and is aligned with the clearance hole. The ultrasonic transducer is disposed in the second mounting hole.

[0036] The second mounting base also has a third mounting hole on its side wall, and the laser collimator is disposed in the third mounting hole;

[0037] The second mounting base also has an optical path channel, which communicates with the third mounting hole and extends to the end of the second mounting base near the object to be tested. The first reflector and the focusing lens are sequentially arranged in the optical path channel, and the photoacoustic beam combining module is arranged in the clearance hole.

[0038] In one embodiment, the drive module includes:

[0039] X-axis drive module, the X-axis drive module is connected to a stage for placing the object to be measured, the X-axis drive module is used to drive the stage to move in the X-axis direction;

[0040] Y-axis drive module, which is connected to the imaging module, is used to drive the imaging module to move in the Y-axis direction;

[0041] The Z-axis drive module is connected to the Y-axis drive module and is used to drive the Y-axis drive module and the imaging module to move in the Z-axis direction.

[0042] In one embodiment, the photoacoustic imaging system further includes a coupling liquid tank, which is connected to the drive module and located between the stage and the imaging module, and the coupling liquid tank is used to contain the coupling liquid.

[0043] In one embodiment, a preprocessing module is further provided between the data processing and control module and the ultrasonic transducer, the preprocessing module being used to amplify and / or filter the imaging signal.

[0044] Secondly, this application also provides a photoacoustic imaging method, implemented using the aforementioned photoacoustic imaging system, comprising the following steps:

[0045] The laser source module emits an excitation laser;

[0046] The optical transmission module combines and / or splits the excited laser beams to form a first laser beam and a second laser beam;

[0047] The driving module drives the imaging module to move relative to the object under test, so that the imaging module performs a scanning operation on the object under test, wherein the scanning operation includes:

[0048] The optical resolution module receives the first laser beam and focuses the first laser beam onto the object under test.

[0049] The acoustic resolution module receives the second laser beam and diffuses the second laser beam onto the object under test; and

[0050] The ultrasonic transducer detects the photoacoustic signal generated by the object under test after being excited by the first laser beam and the second laser beam, and converts the photoacoustic signal into an imaging signal.

[0051] The data processing and control module receives the imaging signal and performs image reconstruction based on the imaging signal.

[0052] In one embodiment, the step of the driving module driving the imaging module to move relative to the object under test, so that the imaging module performs a scanning operation on the object under test, includes:

[0053] Delineate the imaging area on the object to be tested;

[0054] The imaging area is divided into multiple scanning blocks arranged in an array;

[0055] The driving module drives the imaging module to perform the scanning operation on the scanning block in sequence.

[0056] In the aforementioned photoacoustic imaging system and method, the imaging module integrates an optical resolution module, an acoustic resolution module, and an ultrasonic transducer. The focal point of the first laser beam focused by the optical resolution module, the center point of the irradiation area of ​​the second laser beam emitted by the acoustic resolution module, and the detection axis of the photoacoustic signal detected by the ultrasonic transducer are aligned. This allows for simultaneous optical resolution photoacoustic imaging (OR-PAM) and acoustic resolution photoacoustic imaging (AR-PAM) during imaging, thus achieving both centimeter-level high-penetration mesoscopic resolution imaging of deep tissues and millimeter-level shallow microscopic resolution. Specifically, it enables cross-scale imaging of tissue samples, from sub-micrometer resolution microcellular imaging to resolutions of tens of micrometers; for example, shallow tissue imaging can be achieved in sub-nanometer high-resolution microscopic imaging mode; and an imaging depth of approximately 3 millimeters can be obtained in mesoscopic tissue imaging mode. Therefore, automated image signal acquisition and reconstruction can be achieved within a set large imaging field of view, enabling switching between different scale resolutions. For example, a rapid low-resolution scan of the sample can be performed first, followed by switching to a high-resolution mode scan in the region of interest.

[0057] Furthermore, compared to traditional time-sharing designs, the photoacoustic imaging system of this application does not require time-sharing of the optical resolution module and the acoustic resolution module, thus eliminating the need for switching waiting time and meeting the requirements of real-time dynamic observation. Compared to traditional split designs, the optical resolution module, acoustic resolution module, and ultrasonic transducer of this application are integrated into one imaging module, avoiding spatial registration errors and effectively reducing the size and facilitating operation.

[0058] Furthermore, the laser source module of the aforementioned photoacoustic imaging system can provide excitation lasers with multiple wavelengths, pulse frequencies, and energy ranges, thereby covering multiple biomarker characteristics. This allows for the quantitative analysis of different tissue components through multispectral photoacoustic quantitative analysis algorithms. For example, in the ultraviolet band, the characteristic absorption of nucleic acids is utilized to achieve high depth-to-space ratio imaging of tissue cell nuclei; in the visible to near-infrared band, tissue components such as blood vessels, fat, and water are imaged and quantitatively analyzed; and in the mid-infrared band, tissue components such as carbohydrates, lipids, and proteins in cells and tissues are imaged and quantitatively analyzed. Attached Figure Description

[0059] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0060] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Furthermore, the accompanying drawings are not drawn to a 1:1 scale, and the relative dimensions of the various components are shown as examples only and not necessarily to scale. In the accompanying drawings:

[0062] Figure 1 This is a schematic diagram of the structure of a photoacoustic imaging system according to one embodiment.

[0063] Figure 2 This is a schematic diagram of the laser source module and optical transmission module of an embodiment of a photoacoustic imaging system.

[0064] Figure 3 This is a schematic diagram of the imaging module of a photoacoustic imaging system in an embodiment.

[0065] Figure 4 for Figure 3 The diagram shows the structure of the imaging module from another perspective.

[0066] Figure 5 for Figure 3 The image module shown is a cross-sectional view.

[0067] Figure 6 for Figure 5 The imaging module shown is a cross-sectional view from another perspective.

[0068] Figure 7 This is a schematic diagram of the imaging module of a photoacoustic imaging system according to one embodiment.

[0069] Figure 8 This is a schematic diagram of the scanning trajectory of a photoacoustic imaging system according to one embodiment.

[0070] Explanation of reference numerals in the attached figures

[0071] 10. Laser source module; 11. Laser; 20. Optical transmission module; 21. Laser beam combiner module; 211. First beam splitter; 212. Second beam splitter; 221. First optical fiber; 222. First fiber coupler; 231. Second optical fiber; 232. Second fiber coupler; 30. Imaging module; 31. Optical resolution module; 311. Laser collimator; 312. First reflector; 313. Focusing lens; 314. Optical-acoustic beam combiner module; 3141. Second reflector; 32. Acoustic resolution module; 321. First mounting base; 3211, Clearance hole; 3212, First mounting hole; 322, Laser radiator; 33, Ultrasonic transducer; 331, Probe axis; 34, Second mounting base; 341, Second mounting hole; 342, Third mounting hole; 343, Optical path channel; 40, Drive module; 41, X-axis drive module; 411, Stage; 42, Y-axis drive module; 43, Z-axis drive module; 44, Coupling liquid tank; 50, Data processing and control module; 51, Preprocessing module; 60, Object under test; 61, Imaging area; 611, Scanning block. Detailed Implementation

[0072] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0073] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0074] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0075] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0076] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0077] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0078] As described in the background section, current photoacoustic imaging systems cannot simultaneously achieve high-penetration mesoscopic resolution imaging of centimeter-level deep tissues and millimeter-level shallow microscopic resolution. The inventors of this application, through inventive research, have discovered the reason for this:

[0079] Traditional imaging systems (such as VisualSonics Vevo LAZR and iThera Medical MSOT) typically only carry a single imaging module, such as a pure OR-PAM imaging module or a pure AR-PAM imaging module, resulting in a trade-off between resolution and imaging depth. Specifically, while R-PAM imaging modules can provide high resolution of 1~10μm, their imaging depth is less than 1mm, making them unsuitable for detecting large organs or deep lesions; while AR-PAM imaging modules can achieve imaging depths of >10m, their resolution is only 50~200μm, making it difficult to resolve microvascular or cellular structures.

[0080] Some imaging systems, while incorporating both OR-PAM and AR-PAM imaging modules, often integrate these modules as independent scanning units within the same system. In practice, this necessitates time-division switching or separate probe designs, resulting in significant limitations in collaborative imaging. Specifically, in time-sharing switching schemes (such as Fujifilm VisualSonics RSOM), mechanical delays cause the switching time between the OR-PAM imaging module and the AR-PAM imaging module to exceed 30 seconds, which cannot meet the requirements of real-time dynamic observation. In split-type designs (such as the combination of photoacoustic endoscope and ultrasound endoscope), the physical separation of the OR-PAM imaging module and the AR-PAM imaging module results in a spatial registration error of more than 500 micrometers, and the equipment is bulky and complex to operate. More importantly, existing algorithms lack robustness for cross-module data fusion, and the registration of photoacoustic and ultrasound images still relies on manual labeling, resulting in low automation. Furthermore, the physical coupling effect of optical and acoustic signals (such as the phase difference between photoacoustic pressure field and ultrasound echo) is not fully considered when reconstructing multi-module data, leading to a signal-to-noise ratio drop of more than 30% in the fused image. This severely restricts the application value of multi-module imaging in precision medicine and its application flexibility in clinical and scientific research scenarios.

[0081] Based on this, one embodiment of this application provides a photoacoustic imaging system that can balance resolution and imaging depth. Specifically, see... Figure 1 One embodiment of the photoacoustic imaging system includes a laser source module 10, an optical transmission module 20, an imaging module 30, a driving module 40, and a data processing and control module 50, wherein:

[0082] The laser source module 10 is used to provide excitation lasers with multiple wavelengths, multiple pulse frequencies, and multiple energy ranges. In other words, the laser source module 10 can provide excitation lasers that cover the characteristic absorption peaks of multiple biomarkers.

[0083] The optical transmission module 20 is connected to the laser source module 10. The optical transmission module 20 is used to transmit the excitation laser and combine and / or split the excitation laser beam to form a first laser beam and a second laser beam. Specifically, the first laser beam and the second laser beam are two laser beams with different wavelengths, pulse frequencies or energy ranges. The first laser beam is suitable for optical resolution photoacoustic imaging (OR-PAM) and the second laser beam is suitable for second acoustic resolution photoacoustic imaging (AR-PAM).

[0084] The imaging module 30 is positioned relative to the object under test. For example, the photoacoustic imaging system may also include a stage 411, with the imaging module 30 positioned relative to the stage 411, which is used to support the object under test.

[0085] Furthermore, the imaging module 30 includes an optical resolution module 31, an acoustic resolution module 32, and an ultrasonic transducer 33.

[0086] Specifically, the optical resolution module 31 is connected to the optical transmission module 20. The optical resolution module 31 is used to receive the first laser beam and focus the first laser beam onto the object under test to excite the object under test to generate a photoacoustic signal.

[0087] The acoustic resolution module 32 is connected to the optical transmission module 20. The acoustic resolution module 32 is used to receive the second laser beam and irradiate the second laser beam onto the object under test to excite the object under test to generate a photoacoustic signal.

[0088] The ultrasonic transducer 33 is used to detect the photoacoustic signal generated by the object under test after being excited by the first laser beam and / or the second laser beam, and convert the photoacoustic signal into an imaging signal;

[0089] The optical resolution module 31 focuses the focal point of the first laser beam, and the acoustic resolution module 32 emits the center point of the irradiation area of ​​the second laser beam, which is set to coincide with the detection axis 331 of the ultrasonic transducer 33 for detecting photoacoustic signals.

[0090] Furthermore, the drive module 40 is connected to the imaging module 30 and / or the stage 411. The drive module 40 is used to drive the imaging module 30 to move relative to the stage 411 so that the imaging module 30 can scan the object under test.

[0091] The data processing and control module 50 is communicatively connected to the laser source module 10, the ultrasonic transducer 33, and the drive module 40. The data processing and control module 50 controls the operation of the laser source module 10, the ultrasonic transducer 33, and the drive module 40, and performs image reconstruction based on the imaging signals. Specifically, the data processing and control module 50 can be a computer, and it is communicatively connected to the laser source module 10, the ultrasonic transducer 33, and the drive module 40 via cables.

[0092] For example, when the photoacoustic imaging system is working, the laser source module 10 first emits multiple excitation laser beams with different wavelengths, pulse frequencies, and energy ranges. Then, the optical transmission module 20 combines and / or splits the excitation laser beams to form a first laser beam and a second laser beam; and transmits the first laser beam and the second laser beam to the imaging module 30. Subsequently, the optical resolution module 31 receives the first laser beam and focuses it onto the object under test to excite the object to generate a photoacoustic signal. At the same time, the acoustic resolution module 32 receives the second laser beam and diffuses it onto the object under test to excite the object to generate a photoacoustic signal. Then, the ultrasonic transducer 33 detects the photoacoustic signal generated by the object under test after being excited by the first and second laser beams, and converts the photoacoustic signal into an imaging signal. During this process, the drive module 40 drives the imaging module 30 to move relative to the object under test so that the imaging module 30 can perform a full scan of the expected imaging area on the object under test. Finally, the data processing and control module 50 receives the imaging signal and performs image reconstruction based on the imaging signal.

[0093] In the aforementioned photoacoustic imaging system, the imaging module 30 integrates an optical resolution module 31, an acoustic resolution module 32, and an ultrasonic transducer 33. The focal point of the optical resolution module 31 focusing the first laser beam, the center point of the irradiation area of ​​the acoustic resolution module 32 emitting the second laser beam, and the detection axis 331 of the ultrasonic transducer 33 for detecting photoacoustic signals are aligned. This allows for simultaneous optical resolution photoacoustic imaging (OR-PAM) and acoustic resolution photoacoustic imaging (AR-PAM) during imaging, thus achieving both centimeter-level high-penetration mesoscopic resolution imaging of deep tissues and millimeter-level shallow microscopic resolution. Specifically, it enables cross-scale imaging of tissue samples, from sub-micrometer resolution microcellular imaging to resolutions of tens of micrometers. For example, shallow tissue imaging can be achieved in sub-nanometer high-resolution microscopic imaging mode; and an imaging depth of approximately 3 millimeters can be obtained in mesoscopic tissue imaging mode. Therefore, automated image signal acquisition and reconstruction can be achieved within a set large imaging area, enabling switching between different scale resolutions. For instance, a rapid low-resolution scan of the sample can be performed first, followed by switching to high-resolution mode scanning in the region of interest.

[0094] Furthermore, compared to traditional time-sharing designs, the photoacoustic imaging system of this application does not require time-sharing of the optical resolution module 31 and the acoustic resolution module 32, thus eliminating the need for switching waiting time and meeting the requirements of real-time dynamic observation. Compared to traditional split designs, the optical resolution module 31, acoustic resolution module 32, and ultrasonic transducer 33 of this application are integrated into an imaging module 30, avoiding spatial registration errors and effectively reducing the size and facilitating operation.

[0095] Furthermore, the laser source module 10 of the aforementioned photoacoustic imaging system can provide excitation lasers with multiple wavelengths, pulse frequencies, and energy ranges, thereby covering multiple biomarker characteristics. This allows for the quantitative analysis of different tissue components through multispectral photoacoustic quantitative analysis algorithms. For example, in the ultraviolet band, the characteristic absorption of nucleic acids is utilized to achieve high depth-to-space ratio imaging of tissue cell nuclei; in the visible to near-infrared band, tissue components such as blood vessels, fat, and water are imaged and quantitatively analyzed; and in the mid-infrared band, tissue components such as carbohydrates, lipids, and proteins in cells and tissues are imaged and quantitatively analyzed.

[0096] Referring to Figure 1, in some embodiments, the laser source module 10 includes multiple lasers 11, each laser 11 emitting excitation lasers with different wavelengths, pulse frequencies, and / or energy ranges. Specifically, by emitting excitation lasers with different wavelengths, pulse frequencies, and / or energy ranges from different lasers 11, and then combining and splitting the different excitation lasers using the optical transmission module 20, a first laser beam suitable for optical resolution photoacoustic imaging (OR-PAM) and a second laser beam suitable for second acoustic resolution photoacoustic imaging (AR-PAM) can be formed.

[0097] See Figure 1 Optionally, in some embodiments, the optical transmission module 20 includes a laser beam combining module 21, a first optical fiber 221, and a second optical fiber 231. The laser beam combining module 21 is connected to the laser source module 10 and is used to combine and / or split the excitation lasers emitted by different lasers 11 to form a first laser beam and a second laser beam. One end of the first optical fiber 221 is connected to the laser beam combining module 21 via a first optical fiber coupler 222, and the other end of the first optical fiber 221 is connected to the optical resolution module 31. The first optical fiber 221 is used to transmit the first laser beam to the optical resolution module 31. One end of the second optical fiber 231 is connected to the laser beam combining module 21 via a second optical fiber coupler 232, and the other end of the second optical fiber 231 is connected to the acoustic resolution module 32. The second optical fiber 231 is used to transmit the second laser beam to the acoustic resolution module 32.

[0098] The laser beam combining module 21 is used to combine and / or split the excitation lasers emitted by different lasers 11 to form a first laser beam and a second laser beam. The first laser beam is then transmitted to the optical resolution module 31 through the first optical fiber 221, and the second laser beam is transmitted to the acoustic resolution module 32 through the second optical fiber 231. This achieves the dynamic allocation of excitation lasers of specific wavelengths to the optical resolution module 31 and the acoustic resolution module 32, respectively.

[0099] See Figure 2Specifically, in some embodiments, the laser beam combining module 21 includes a plurality of first beam splitters 211 and a plurality of second beam splitters 212. Wherein:

[0100] Multiple first beam splitters 211 are configured one-to-one with multiple lasers 11. All first beam splitters 211 are used to couple a first wavelength laser suitable for optical resolution module 31 into a first optical fiber 221 to form a first laser beam.

[0101] For example, a plurality of first beam splitters 211 are arranged at intervals relative to each other. The front side of the first beam splitter 211 can reflect the first wavelength laser and transmit lasers of other wavelengths. The back side of the first beam splitter 211 can transmit the first wavelength laser. In this way, the first beam splitter 211 can filter the laser emitted by the laser 11 to couple the first wavelength laser suitable for the optical resolution module 31 into the first optical fiber 221.

[0102] Similarly, multiple second beam splitters 212 are configured one-to-one with multiple lasers 11. All the second beam splitters 212 are used to couple the second wavelength laser suitable for the optical resolution module 31 into the second optical fiber 231 to form a second laser beam.

[0103] For example, a plurality of second beam splitters 212 are arranged at intervals relative to each other. The front side of the second beam splitter 212 can reflect the second wavelength laser and transmit lasers of other wavelengths, while the back side of the second beam splitter 212 can transmit the first wavelength laser. In this way, the first beam splitter 211 can filter the laser emitted by the laser 11 to couple the second wavelength laser suitable for the optical resolution module 31 into the second optical fiber 231.

[0104] See Figure 1 Optionally, in some embodiments, the optical resolution module 31 includes a laser collimator 311, a first reflector 312, a focusing lens 313, and a photoacoustic beam combining module 314.

[0105] The laser collimator 311 is connected to the optical transmission module 20. The laser collimator 311 is used to receive the first laser beam. Specifically, the laser collimator 311 is connected to the first optical fiber 221.

[0106] The first reflector 312 is arranged in the optical path of the first laser beam emitted from the laser collimator 311. The first reflector 312 is used to reflect the first laser beam, thereby changing the path of the first laser beam.

[0107] A focusing mirror 313 is arranged in the optical path of the first laser beam reflected by the first mirror, and the focusing mirror 313 is used to focus the first laser beam.

[0108] The photoacoustic beam combining module 314 is disposed between the stage 411 and the ultrasonic transducer 33. The photoacoustic beam combining module 314 is used to guide the first laser beam focused by the focusing lens 313 to be incident on the object under test, and to make the incident optical path of the first laser beam on the object under test coaxial with the detection axis 331 of the ultrasonic transducer 33, thereby ensuring that the focal point of the first laser beam focused by the optical resolution module 31 coincides with the detection axis 331 of the ultrasonic transducer 33, thereby realizing optical resolution imaging.

[0109] Furthermore, the photoacoustic beam combining module 314 can be penetrated by the photoacoustic signal, so that while ensuring that the photoacoustic beam combining module 314 can guide the first laser beam to coincide with the detection axis 331 of the ultrasonic transducer 33, it does not affect the transmission of the photoacoustic signal to the ultrasonic transducer 33.

[0110] For example, the photoacoustic beam combining module 314 includes a plurality of second reflectors 3141 arranged in sequence relative to each other. The plurality of second reflectors 3141 are used to reflect the first laser beam in sequence to guide the first laser beam to be incident on the object under test at an angle coaxial with the detection axis 331 of the ultrasonic transducer 33, thereby ensuring that the incident path of the first laser beam is coaxial with the detection axis 331 of the ultrasonic transducer 33, thereby achieving optical resolution imaging.

[0111] See Figure 1 The acoustic resolution module 32 includes multiple laser diverging elements 322, all of which are connected to the optical transmission module 20. Each laser diverging element 322 is used to irradiate a second laser beam onto the object under test. For example, each laser diverging element 322 is connected to a corresponding number of second optical fibers 231.

[0112] Furthermore, multiple laser diverging elements 322 are arranged at intervals along the outer periphery of the ultrasonic transducer 33, and the laser diverging elements 322 are tilted relative to the detection axis 331 of the ultrasonic transducer 33, so that the center point of the irradiation area formed by all the laser diverging elements 322 on the object under test coincides with the detection axis 331 of the ultrasonic transducer 33, thereby achieving acoustic resolution imaging.

[0113] See Figures 3 to 6 In some embodiments, the imaging module 30 further includes a first mounting base 321, which has an annular structure and is disposed between the ultrasonic transducer 33 and the stage 411. The first mounting base 321 is provided with a through hole 3211 for avoiding the first laser beam and photoacoustic signal. A plurality of first mounting holes 3212 are provided at intervals along the circumference of the first mounting base 321, and the laser emitting element 322 is installed in the first mounting hole 3212 in a corresponding manner.

[0114] All laser emitting elements 322 are mounted on the annular first mounting base 321, so that the laser emitting elements 322 can be arranged at intervals around the outer periphery of the ultrasonic transducer 33. At the same time, the first laser beam and photoacoustic signal are avoided by using the clearance hole 3211 of the first mounting base 321, thus avoiding the first mounting base 321 from blocking the first laser beam and photoacoustic signal.

[0115] See Figure 5 as well as Figure 6 In one embodiment, the imaging module 30 further includes a second mounting base 34, which is connected to the drive module 40, and a first mounting base 321 is connected to one end of the second mounting base 34 near the stage 411.

[0116] See Figure 5 Furthermore, the second mounting base 34 has a second mounting hole 341, which extends to one end of the second mounting base 34 near the stage 411 and is aligned with the clearance hole 3211. The ultrasonic transducer 33 is disposed in the second mounting hole 341, thereby ensuring that the ultrasonic transducer 33 can receive photoacoustic signals through the clearance hole 3211.

[0117] See Figure 5 For example, the second mounting base 34 also has a third mounting hole 342 on its side wall, and the laser collimator 311 is disposed in the third mounting hole 342. Further, the second mounting base 34 also has an optical path channel 343, which communicates with the third mounting hole 342 and extends to the end of the second mounting base 34 near the stage 411. The first reflecting mirror 312 and the focusing mirror 313 are sequentially disposed in the optical path channel 343, and the photoacoustic beam combining module 314 is disposed in the clearance hole 3211. Thus, after the first laser beam enters the laser collimator 311, it can be sequentially transmitted along the optical path channel 343 to the first reflecting mirror 312 and the focusing mirror 313, and after being focused by the focusing mirror 313, it enters the photoacoustic beam combining module 314, which guides the focused first laser beam to the object under test.

[0118] See Figure 7 Optionally, in one embodiment, the driving module 40 includes an X-axis driving module 41, a Y-axis driving module 42, and a Z-axis driving module 43. The X-axis driving module 41 is connected to the stage 411 and is used to drive the stage 411 to move in the X-axis direction. The Y-axis driving module 42 is connected to the imaging module 30 and is used to drive the imaging module 30 to move in the Y-axis direction. The Z-axis driving module 43 is connected to the Y-axis driving module 42 and is used to drive both the Y-axis driving module 42 and the imaging module 30 to move in the Z-axis direction.

[0119] It is easy to understand that the X-axis, Y-axis and Z-axis are set perpendicular to each other. In this way, by using the X-axis drive module 41, Y-axis drive module 42 and Z-axis drive module 43 to work together, the imaging module 30 and the stage 411 can move relative to each other on the X-axis, Y-axis and Z-axis, thereby enabling the imaging module 30 to scan the object to be measured on the stage 411.

[0120] For example, in some embodiments, the X-axis drive module 41, the Y-axis drive module 42, and the Z-axis drive module 43 can be a mobile platform, a linear module, an electric actuator, a two-dimensional scanning galvanometer, or a two-dimensional scanning MEMS drive module 40, etc., without limitation.

[0121] See Figure 7 The photoacoustic imaging system also includes a coupling fluid tank 44, which is connected to the drive module 40 and located between the stage 411 and the imaging module 30. The coupling fluid tank 44 is used to contain the coupling fluid. Specifically, in actual operation, the coupling fluid tank 44 moves synchronously with the stage 411, and the receiving end of the ultrasonic transducer 33 is immersed in the coupling fluid so that the photoacoustic signal can be transmitted to the ultrasonic transducer 33 through the coupling fluid.

[0122] See Figure 1 Optionally, in some embodiments, a preprocessing module 51 is further provided between the data processing and control module 50 and the ultrasonic transducer 33. The preprocessing module 51 is used to amplify and / or filter the imaging signal. This ensures that the data processing and control module 50 can receive a clear imaging signal.

[0123] Another embodiment of this application also provides a photoacoustic imaging method implemented using the photoacoustic imaging system of any of the above embodiments. Specifically, the photoacoustic imaging method includes the following steps:

[0124] S110: Laser source module 10 emits excitation laser;

[0125] Specifically, each laser 11 in the laser source module 10 emits a variety of excitation lasers with different wavelengths, different pulse frequencies, and different energy ranges.

[0126] S120: The optical transmission module 20 will excite laser beam combining and / or beam splitting to form a first laser beam and a second laser beam;

[0127] Specifically, the laser beam combining module 21 of the optical transmission module 20 couples a first wavelength laser suitable for the optical resolution module 31 into the first optical fiber 221 to form a first laser beam. At the same time, the laser beam combining module 21 couples a second wavelength laser suitable for the acoustic resolution module 32 into the second optical fiber 231 to form the first laser beam.

[0128] S130: The driving module 40 drives the imaging module 30 to move relative to the stage 411 so that the imaging module 30 can perform a scanning operation on the object to be tested placed on the stage 411.

[0129] Specifically, the scanning operation includes:

[0130] S131: Optical resolution module 31 receives the first laser beam and focuses the first laser beam onto the object to be measured;

[0131] S132: The acoustic resolution module 32 receives the second laser beam and irradiates the object under test with the second laser beam;

[0132] S133: The ultrasonic transducer 33 detects the photoacoustic signal generated by the object under test 60 after being excited by the first laser beam and the second laser beam, and converts the photoacoustic signal into an imaging signal.

[0133] S140: The data processing and control module 50 receives the imaging signal and performs image reconstruction based on the imaging signal.

[0134] like Figure 8 As shown, exemplarily, in some embodiments, step S130 further includes the following steps:

[0135] S134: Define the imaging region 61 on the object to be tested 60;

[0136] S135: Divide the imaging area 61 into multiple scanning blocks 611 arranged in an array;

[0137] S136: The driving module 40 drives the imaging module 30 to perform scanning operations on the scanning block 611 in sequence.

[0138] Specifically, by first defining a large imaging area 61 on the object under test 60, and then dividing the imaging area 61 into several individual high-resolution scanning blocks 611, during the imaging process, the driving module 40 will drive the imaging module 30 to complete the high-resolution imaging of a small scanning block 611 in a point-by-point scanning manner, and then the imaging module 30 will be driven to the next scanning block 611 for the next round of high-resolution small-area imaging. By repeating the above process, high-resolution imaging can be performed on the defined large imaging area 61.

[0139] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0140] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A photoacoustic imaging system, characterized in that, include: The laser source module (10) is used to provide excitation lasers with multiple wavelengths, multiple pulse frequencies and multiple energy ranges; An optical transmission module (20) is connected to the laser source module (10) for transmitting excitation laser and combining and / or splitting the excitation laser to form a first laser beam and a second laser beam; An imaging module (30) is configured relative to the object under test (60), the imaging module (30) comprising: An optical resolution module (31) is connected to the optical transmission module (20) and is used to focus the first laser beam onto the object under test (60). An acoustic resolution module (32) is connected to the optical transmission module (20) and is used to irradiate the object under test (60) with the second laser beam. An ultrasonic transducer (33) is used to detect the photoacoustic signal generated by the object under test (60) after being excited by the first laser beam and / or the second laser beam, and to convert the photoacoustic signal into an imaging signal; The optical resolution module (31) focuses the focal point of the first laser beam, and the acoustic resolution module (32) diverges the center point of the irradiation area of ​​the second laser beam, which is set to coincide with the detection axis (331) of the ultrasonic transducer (33) for detecting the photoacoustic signal. A driving module (40) is used to drive the imaging module (30) to move relative to the object under test (60); The data processing and control module (50) is used to control the operation of the laser source module (10), the ultrasonic transducer (33) and the drive module (40), and to perform image reconstruction based on the imaging signal.

2. The photoacoustic imaging system according to claim 1, characterized in that, The laser source module (10) includes multiple lasers (11), and different lasers (11) are used to emit excitation lasers with different wavelengths, different pulse frequencies and / or different energy ranges.

3. The photoacoustic imaging system according to claim 2, characterized in that, The optical transmission module (20) includes: Laser beam combining module (21), which is connected to the laser source module (10), is used to combine and / or split the excitation lasers emitted by different lasers (11) to form the first laser beam and the second laser beam; The first optical fiber (221) has one end connected to the laser beam combining module (21) via a first optical fiber coupler (222), and the other end connected to the optical resolution module (31). The first optical fiber (221) is used to transmit the first laser beam to the optical resolution module (31). The second optical fiber (231) has one end connected to the laser beam combining module (21) via a second optical fiber coupler (232), and the other end connected to the acoustic resolution module (32). The second optical fiber (231) is used to transmit the second laser beam to the acoustic resolution module (32).

4. The photoacoustic imaging system according to claim 3, characterized in that, The laser beam combining module (21) includes: Multiple first beam splitters (211) are provided in a one-to-one correspondence with multiple lasers (11). All the first beam splitters (211) are used to jointly couple a first wavelength laser suitable for the optical resolution module (31) into the first optical fiber (221) to form the first laser beam. Multiple second beam splitters (212) are provided in a one-to-one correspondence with multiple lasers (11). All the second beam splitters (212) are used to jointly couple a second wavelength laser suitable for the acoustic resolution module (32) into the second optical fiber (231) to form the second laser beam.

5. The photoacoustic imaging system according to claim 1, characterized in that, The optical resolution module (31) includes: A laser collimator (311) is connected to the optical transmission module (20) and is used to receive the first laser beam. A first reflector (312) is arranged in the optical path of the first laser beam emitted from the laser collimator (311), and the first reflector (312) is used to reflect the first laser beam. A focusing lens (313) is arranged in the optical path of the first laser beam reflected by the first reflecting mirror (312), and the focusing lens (313) is used to focus the first laser beam; A photoacoustic beam combining module (314) is disposed between the object under test (60) and the ultrasonic transducer (33). The photoacoustic beam combining module (314) is used to guide the first laser beam focused by the focusing lens (313) to be incident on the object under test (60), and to make the incident optical path of the first laser beam on the object under test (60) coaxial with the detection axis (331) of the ultrasonic transducer (33). The photoacoustic beam combining module (314) can be penetrated by the photoacoustic signal.

6. The photoacoustic imaging system according to claim 5, characterized in that, The photoacoustic beam combining module (314) includes a plurality of second reflectors (3141) arranged in sequence opposite to each other. The plurality of second reflectors (3141) are used to reflect the first laser beam in sequence to guide the first laser beam to be incident on the object under test (60) at an angle coaxial with the detection axis (331) of the ultrasonic transducer (33).

7. The photoacoustic imaging system according to claim 5, characterized in that, The acoustic resolution module (32) includes multiple laser diverging elements (322), all of which are connected to the optical transmission module (20). The laser diverging elements (322) are used to irradiate the second laser beam onto the object under test (60). The multiple laser diverging elements (322) are arranged at intervals along the outer periphery of the ultrasonic transducer (33), and the laser diverging elements (322) are tilted relative to the detection axis (331) of the ultrasonic transducer (33) so that the center point of the irradiation area formed by all the laser diverging elements (322) on the object under test (60) coincides with the detection axis (331) of the ultrasonic transducer (33).

8. The photoacoustic imaging system according to claim 7, characterized in that, The imaging module (30) further includes a first mounting base (321), which has a ring structure and is disposed between the ultrasonic transducer (33) and the object under test (60). The first mounting base (321) is provided with a through hole (3211) for avoiding the first laser beam and the photoacoustic signal. A plurality of first mounting holes (3212) are provided at intervals along the circumference of the first mounting base (321), and the laser emitting element (322) is installed in the first mounting hole (3212) one by one.

9. The photoacoustic imaging system according to claim 8, characterized in that, The imaging module (30) also includes a second mounting base (34); The second mounting base (34) is connected to the drive module (40), and the first mounting base (321) is connected to the end of the second mounting base (34) near the object under test (60); The second mounting base (34) has a second mounting hole (341), which extends to one end of the second mounting base (34) near the object to be tested (60) and is aligned with the clearance hole (3211). The ultrasonic transducer (33) is disposed in the second mounting hole (341). The second mounting base (34) also has a third mounting hole (342) on its side wall, and the laser collimator (311) is disposed in the third mounting hole (342); The second mounting base (34) is also provided with an optical path channel (343), which is connected to the third mounting hole (342) and extends to the end of the second mounting base (34) near the object to be tested (60). The first reflector (312) and the focusing lens (313) are sequentially arranged in the optical path channel (343), and the photoacoustic beam combining module (314) is arranged in the clearance hole (3211).

10. The photoacoustic imaging system according to claim 1, characterized in that, The drive module (40) includes: X-axis drive module (41), the X-axis drive module (41) is connected to a stage (411) for placing the object to be measured (60), the X-axis drive module (41) is used to drive the stage (411) to move in the X-axis direction; Y-axis drive module (42), which is connected to the imaging module (30), is used to drive the imaging module (30) to move in the Y-axis direction; Z-axis drive module (43), which is connected to Y-axis drive module (42), is used to drive Y-axis drive module (42) and imaging module (30) to move in the Z-axis direction.

11. The photoacoustic imaging system according to claim 10, characterized in that, The photoacoustic imaging system also includes a coupling liquid tank (44), which is connected to the drive module (40) and located between the stage (411) and the imaging module (30). The coupling liquid tank (44) is used to contain the coupling liquid.

12. The photoacoustic imaging system according to claim 1, characterized in that, A preprocessing module (51) is also provided between the data processing and control module (50) and the ultrasonic transducer (33). The preprocessing module (51) is used to amplify and / or filter the imaging signal.

13. A photoacoustic imaging method, implemented using the photoacoustic imaging system according to any one of claims 1-12, characterized in that, Includes the following steps: The laser source module (10) emits an excitation laser; The optical transmission module (20) combines and / or splits the excitation laser beams to form a first laser beam and a second laser beam; The driving module (40) drives the imaging module (30) to move relative to the object under test (60), so that the imaging module (30) performs a scanning operation on the object under test (60), wherein the scanning operation includes: The optical resolution module (31) receives the first laser beam and focuses the first laser beam onto the object under test (60). The acoustic resolution module (32) receives the second laser beam and diffuses the second laser beam onto the object under test (60); and The ultrasonic transducer (33) detects the photoacoustic signal generated by the object under test after being excited by the first laser beam and the second laser beam, and converts the photoacoustic signal into an imaging signal; The data processing and control module (50) receives the imaging signal and performs image reconstruction based on the imaging signal.

14. The photoacoustic imaging method according to claim 13, characterized in that, The step of the driving module (40) driving the imaging module (30) to move relative to the object under test (60) so that the imaging module (30) can perform a scanning operation on the object under test (60) includes: An imaging region (61) is defined on the object to be tested (60); The imaging area (61) is divided into multiple scanning blocks (611) arranged in an array. The driving module (40) drives the imaging module (30) to perform the scanning operation on the scanning block (611) in sequence.

Images