Three-dimensional photoacoustic imaging method and system based on two-dimensional outline of imaging part

Abstract

The invention relates to the technical field of photoacoustic imaging, in particular to a three-dimensional photoacoustic imaging method and system based on a two-dimensional outline of an imaging part. The method comprises the following steps: extracting a two-dimensional contour of an imaging part, and planning a two-dimensional moving path according to the two-dimensional contour; according to the two-dimensional moving path, the position coordinates of the movement of the mechanical arm are obtained; adjusting the position of the photoacoustic imaging probe based on the position coordinates, and adjusting the posture of the photoacoustic imaging probe according to the mechanical information of the photoacoustic imaging probe; and completing the three-dimensional photoacoustic imaging of the target area by using the photoacoustic imaging probe with the updated attitude. According to the invention, full-coverage conformal three-dimensional photoacoustic imaging of the outline of the imaging part is realized through the low-cost two-dimensional camera, and the problems that in the three-dimensional photoacoustic imaging technology based on photoacoustic tomography, the luminous flux distribution of imaging planes in different target areas is inconsistent due to the fixed orientation of a probe, an imaging blind area exists, and the imaging range is limited are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photoacoustic imaging, and in particular to a three-dimensional photoacoustic imaging method and system based on a two-dimensional contour of an imaging part. Background Art

[0002] Photoacoustic imaging is an advanced medical imaging technology that combines the advantages of optical imaging and ultrasound imaging. It generates high-resolution images by using laser-excited ultrasonic signals generated by tissues, and can accurately display the structure and function inside tissues. In terms of vascular imaging, PAI has unique advantages. It can provide high-definition images of blood vessels and non-invasively detect the morphology and function of blood vessels by analyzing blood components at multiple wavelengths. Therefore, photoacoustic imaging has shown high accuracy and application potential in the early diagnosis, evaluation and monitoring of vascular diseases.

[0003] At present, ultrasonic transducers based on linear arrays are often used as photoacoustic imaging probes in photoacoustic tomography systems to achieve three-dimensional photoacoustic imaging scanning because of their low cost, wide availability in clinical environments, and easy integration with existing medical imaging systems. The scanning method is mainly to linearly move the photoacoustic probe along the x, y, and z axes of the target part, obtain two-dimensional tomographic images, and perform three-dimensional reconstruction in combination with spatial coordinates. At present, a method for three-dimensional photoacoustic imaging of the foot has been proposed. This method adjusts the angle of the contact surface between the dorsum of the foot and the photoacoustic probe so that the probe remains parallel and equidistant to the dorsum of the foot during axial scanning, thereby achieving three-dimensional photoacoustic imaging with consistent light flux. However, this method has the following limitations: first, the imaging site needs to be immersed in water, which limits its wide application in clinical practice; second, this method is only applicable to specific sites such as the foot and lacks versatility. Another document proposes a three-dimensional photoacoustic vascular imaging system with force control, which uses a force sensor to press the probe on the skin surface coated with an ultrasound coupling coagulant, and ensures that the axial scanning imaging is performed after sufficient coupling. This system can achieve three-dimensional photoacoustic imaging of flat tissues with consistent light flux, and does not require water or special equipment, and is relatively convenient to operate. However, since the probe can only move in the axial direction, it cannot fully couple to non-flat parts, so this method is only applicable to small-scale, flat imaging parts. In the field of ultrasound imaging, studies have proposed scanning imaging by adjusting the angle of the B-ultrasound probe inside and outside the imaging plane. Ultrasound imaging mainly relies on the propagation and reflection of sound waves, so the adjustment of the probe is aimed at optimizing the incident angle of the sound wave and the receiving efficiency of the reflected signal to ensure good acoustic coupling and image continuity. Unlike ultrasound imaging, in photoacoustic imaging, since different skin structures have different refractive indices, light scattering and light absorption coefficients, and the skin surface presents different curvature changes at different imaging positions, the adjustment of the photoacoustic probe not only needs to maintain acoustic coupling and image continuity, but also needs to ensure that the incident light angle is consistent, the light flux is concentrated on the imaging plane in the tissue and evenly distributed, thereby improving the photoacoustic signal intensity and imaging quality. In three-dimensional photoacoustic imaging, the most ideal imaging method is to achieve coaxial light excitation and sound propagation in the imaging depth direction during the scanning process, which can not only effectively avoid imaging blind spots, but also significantly improve the signal-to-noise ratio and imaging depth of the photoacoustic image. However, when scanning with an axial linear motion probe, it is often difficult to maintain a constant distance between the probe and the skin surface, to maintain the consistency of the incident light angle inside the tissue, and to effectively concentrate the light flux on the imaging plane of the tissue. This makes it difficult to maintain a uniform distribution of light flux when scanning non-flat surfaces, and may create imaging blind spots during the scanning process, thereby affecting the signal-to-noise ratio and imaging depth of the image, and ultimately making it difficult to ensure the accuracy of the three-dimensional photoacoustic image. The current three-dimensional photoacoustic imaging method based on photoacoustic tomography has difficulty in performing full coverage scanning of non-flat areas, resulting in the inability to obtain a complete vascular structure map, which affects the accurate assessment, early diagnosis, and subsequent detection of the disease.Therefore, there is an urgent need to solve the problems of inconsistent light flux distribution in the imaging plane in different target areas, the existence of imaging blind spots and limited imaging range due to the fixed orientation of the probe in three-dimensional photoacoustic imaging technology based on photoacoustic tomography. Summary of the invention

[0004] In view of the shortcomings of the existing methods and the needs of practical applications, on the one hand, the present invention provides a three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part, comprising the following steps: Extract the two-dimensional contour of the imaging part, plan the two-dimensional moving path according to the two-dimensional contour; obtain the position coordinates of the mechanical arm movement according to the two-dimensional moving path; adjust the position of the photoacoustic imaging probe based on the position coordinates, and adjust the posture of the photoacoustic imaging probe through the mechanical information of the photoacoustic imaging probe; use the photoacoustic imaging probe with updated posture to complete the three-dimensional photoacoustic imaging of the target area. The present invention realizes full coverage conformal three-dimensional photoacoustic imaging of the contour of the imaging part through a low-cost two-dimensional camera, solves the problem of inconsistent light flux distribution in the imaging plane in different target areas, the existence of imaging blind spots and limited imaging range due to the fixed orientation of the probe in the three-dimensional photoacoustic imaging technology based on photoacoustic tomography, and is further conducive to ensuring the consistency of light flux during the three-dimensional photoacoustic imaging process, realizing quantitative photoacoustic imaging of different parts of the human body, thereby ensuring the consistency of imaging conditions and the reliability of results, making the evaluation of vascular morphology and function more accurate, which is of great significance for the early diagnosis, evaluation and monitoring of vascular diseases.

[0005] Optionally, the two-dimensional contour of the extracted imaging part satisfies the following formula: in, represents the difference image, Represents the pixel value of the background image, Represents the pixel value of the image containing the target part, The present invention effectively isolates the target by extracting the two-dimensional contour of the imaging part, reduces the interference of the background, and effectively improves the imaging accuracy of the present invention.

[0006] Optionally, the two-dimensional moving path is planned according to the two-dimensional contour, satisfying the following formula: in, Indicates The coordinates of the sampling path points, represents the set of target contour points, Represents the total number of contour points, Indicates the number of path points that are expected to be sampled. The sampling by the planning method of the present invention can select representative path points at intervals and adjust the number of path points to meet different accuracy and calculation requirements.

[0007] Optionally, obtaining the position coordinates of the robot arm movement according to the two-dimensional moving path comprises the following steps: According to the two-dimensional moving path, the three-dimensional coordinates in the camera coordinate system are obtained; and the position coordinates of the movement of the robotic arm are obtained by using the three-dimensional coordinates. The present invention constructs a rotation transfer matrix based on the actual probe and robotic arm coordinate systems, which can clearly coordinate the relationship between the robotic arm base coordinate system and the photoacoustic imaging probe coordinate system, which is conducive to the subsequent use of the robotic arm to adjust the photoacoustic imaging probe.

[0008] Optionally, the three-dimensional coordinates in the camera coordinate system are obtained according to the two-dimensional moving path, satisfying the following formula: in, , Represents the coordinates of the pixel points of the two-dimensional image in the two-dimensional moving path, represents the focal length of the camera, represents the position of the camera optical axis projection on the image plane, represents the vertical distance from the camera to the imaging platform, Represents the coordinates of the pixel in the camera coordinate system.

[0009] Optionally, the three-dimensional coordinates are used to obtain the position coordinates of the robot arm movement, satisfying the following formula: in, , , represents the coordinates of the robot base, , , Represents the three-dimensional coordinates in the camera coordinate system, Represents the rotation matrix of the camera coordinate system relative to the robot coordinate system, Represents the translation vector of the camera coordinate system relative to the robot coordinate system.

[0010] Optionally, adjusting the position of the photoacoustic imaging probe based on the position coordinates comprises the following steps: According to the position coordinates, the displacement acceleration of the photoacoustic imaging probe is obtained; the new displacement velocity is calculated using the displacement acceleration; and the updated position of the photoacoustic imaging probe is calculated according to the new displacement velocity.

[0011] Optionally, the displacement acceleration of the photoacoustic imaging probe is obtained according to the position coordinates, satisfying the following formula: in, represents the displacement acceleration of the photoacoustic imaging probe, represents the mass matrix, represents the contact force between the probe and the skin, represents the damping matrix, represents the expected speed, represents the speed at the previous moment, represents the stiffness matrix, represents the desired target position, The present invention can achieve accurate control of the probe position by adjusting the parameters of the mass, damping and stiffness matrix to keep the contact force between the probe and the skin surface consistent.

[0012] Optionally, adjusting the posture of the photoacoustic imaging probe according to the mechanical information of the photoacoustic imaging probe comprises the following steps: According to the mechanical information, the rotational acceleration of the mechanical arm is obtained; through the rotational acceleration, the angular velocity of the mechanical arm is obtained; and the new posture of the photoacoustic imaging probe is obtained using the angular velocity. The present invention adjusts the rotational acceleration of the mechanical arm through external torque feedback, thereby achieving posture adjustment, which is beneficial to improving the adaptability of non-flat parts and the accuracy of imaging results.

[0013] In the second aspect, in order to efficiently execute the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part provided by the present invention, the present invention also provides a three-dimensional photoacoustic imaging system based on the two-dimensional contour of the imaging part, including a processor, an input device, an output device and a memory, wherein the processor, the input device, the output device and the memory are interconnected, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part as described in the first aspect of the present invention. The three-dimensional photoacoustic imaging system based on the two-dimensional contour of the imaging part of the present invention has a compact structure and stable performance, and can stably execute the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part provided by the present invention, further improving the overall applicability and practical application ability of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A flow chart of a three-dimensional photoacoustic imaging method based on a two-dimensional contour of an imaging part provided by an embodiment of the present invention; Figure 2A schematic diagram of a scanning method of the present invention and a conventional scanning method provided in an embodiment of the present invention; Figure 3 A framework diagram of a three-dimensional photoacoustic imaging device based on a two-dimensional contour of an imaging part provided by an embodiment of the present invention; Figure 4 A framework diagram of a three-dimensional photoacoustic imaging system based on a two-dimensional contour of an imaging part provided by an embodiment of the present invention; Figure 5 A schematic structural diagram of a three-dimensional photoacoustic imaging device based on a two-dimensional contour of an imaging part provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0016] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0017] See also Figure 1 In order to solve the problems of inaccurate imaging results, inapplicability to non-flat parts and limited imaging range in dry-coupled three-dimensional photoacoustic imaging of a moving photoacoustic imaging probe position, the present invention provides a three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part, such as Figure 1 In one embodiment, the method comprises the following steps: S1. Extracting a two-dimensional contour of an imaging part, and planning a two-dimensional moving path according to the two-dimensional contour.

[0018] In an embodiment, when there is no target part, a two-dimensional camera is used to capture an image of the imaging platform as a reference of the scene. When the target part exists, the captured image includes a combination of the target and the background. By comparing the background image with the target image, the difference between the two is identified, thereby extracting the area of ​​the target part. This process can effectively isolate the target and reduce the interference of the background.

[0019] Specifically, background subtraction is to extract the two-dimensional contour of the imaging part, satisfying the following formula: in, represents the difference image, Represents the pixel value of the background image, Represents the pixel value of the image containing the target part, Represents absolute value operation. Remove the background effect from the target image, so as to highlight the target area and replace the background image and the target image Perform pixel-level differentiation to generate a new differential image , to reflect the difference between the two.

[0020] For each pixel coordinate, take the pixel values ​​of the background image and the target image at that position, calculate their difference, and take the absolute value (to avoid negative values); in the difference result, the pixel position with a larger value represents the area of ​​the target part, because the pixel value of the target part is significantly different from the background; further, the difference of the background part (static area) is close to zero, and the pixel value is low; the difference of the target part (dynamic area) is large, and the pixel value is high, so that the target area can be separated from the image.

[0021] Furthermore, a two-dimensional moving path is planned according to the two-dimensional contour, satisfying the following formula: in, Indicates The coordinates of the sampling path points, represents the set of target contour points, Represents the total number of contour points, i.e. Length, Indicates the number of path points you want to sample.

[0022] pass Calculate the fixed interval between every two sampling points, for each path point Calculate its index position in the contour point array , and finally from Select the point with the corresponding index , and then plan a two-dimensional moving path. By controlling the value of M, the number of path points can be adjusted to meet different accuracy and calculation requirements.

[0023] S2. Obtain the position coordinates of the robot arm movement according to the two-dimensional moving path.

[0024] In an embodiment, obtaining the position coordinates of the robot arm movement according to the two-dimensional moving path comprises the following steps: S21. Obtain three-dimensional coordinates in a camera coordinate system according to the two-dimensional moving path.

[0025] Specifically, the three-dimensional coordinates in the camera coordinate system are obtained according to the two-dimensional moving path, satisfying the following formula: in, , Represents the coordinates of the pixel points of the two-dimensional image in the two-dimensional moving path, represents the focal length of the camera, represents the position of the camera optical axis projection on the image plane, represents the vertical distance from the camera to the imaging platform, Represents the coordinates of the pixel in the camera coordinate system.

[0026] S22. Using the three-dimensional coordinates, obtain the position coordinates of the robot arm movement.

[0027] Specifically, the three-dimensional coordinates are used to obtain the position coordinates of the robot arm movement, satisfying the following formula: in, , , represents the coordinates of the robot base, , , Represents the three-dimensional coordinates in the camera coordinate system, Represents the rotation matrix of the camera coordinate system relative to the robot coordinate system, It represents the translation vector of the camera coordinate system relative to the robot coordinate system. It should be understood that the camera coordinate system and the robot motion coordinate system are generally two different coordinate systems, and the mapping between the two needs to be achieved through coordinate system conversion.

[0028] S3. Adjust the position of the photoacoustic imaging probe based on the position coordinates, and adjust the posture of the photoacoustic imaging probe according to the mechanical information of the photoacoustic imaging probe.

[0029] In an embodiment, adjusting the position of the photoacoustic imaging probe based on the position coordinates comprises the following steps: S31. Obtaining the displacement acceleration of the photoacoustic imaging probe according to the position coordinates.

[0030] Specifically, the displacement acceleration of the photoacoustic imaging probe is obtained according to the position coordinates, satisfying the following formula: in, represents the displacement acceleration of the photoacoustic imaging probe, represents the mass matrix, represents the contact force between the probe and the skin, represents the damping matrix, represents the expected speed, represents the speed at the previous moment, represents the stiffness matrix, represents the desired target position, Indicates the position at the previous moment.

[0031] S32. Calculate a new displacement velocity using the displacement acceleration.

[0032] Specifically, the new displacement velocity is calculated using the displacement acceleration to satisfy the following formula: in, represents the new displacement velocity, represents the speed at the previous moment, represents the displacement acceleration of the photoacoustic imaging probe, Represents the time step.

[0033] S33, calculating the updated position of the photoacoustic imaging probe according to the new displacement velocity.

[0034] In the embodiment, the updated position of the photoacoustic imaging probe is calculated according to the new displacement speed, satisfying the following formula: in, Indicates the updated position of the photoacoustic imaging probe. represents the position at the previous moment, represents the speed at the previous moment, represents the new displacement velocity, Represents the time step.

[0035] Furthermore, the position of the photoacoustic imaging probe is updated through control of a host computer of the robotic arm.

[0036] Furthermore, adjusting the posture of the photoacoustic imaging probe according to the mechanical information of the photoacoustic imaging probe comprises the following steps: S34. Obtain the rotational acceleration of the robotic arm according to the mechanical information.

[0037] Specifically, according to the mechanical information, the rotational acceleration of the robot arm is obtained, which satisfies the following formula: in, represents the rotational acceleration of the robot arm, represents the inertia matrix of the robot arm, represents the external feedback torque, represents the damping matrix, represents the desired angular velocity, represents the angular velocity at the previous moment, represents the stiffness matrix, represents the desired pose of the photoacoustic imaging probe, Indicates the posture of the photoacoustic imaging probe at the previous moment. The external feedback torque refers to the influence of contact or external force, the damping matrix, the response of controlling the rotation speed, the stiffness matrix, the response of controlling the rotation error, and the posture is usually expressed by Euler angles. .

[0038] S35. Obtain the angular velocity of the robotic arm through the rotational acceleration.

[0039] By calculating the rotational acceleration, we get the new angular velocity, which satisfies the following formula: in, represents the new angular velocity, represents the angular velocity at the previous moment, represents the rotational acceleration of the robot arm, is the time step.

[0040] S36: using the angular velocity, obtaining a new posture of the photoacoustic imaging probe.

[0041] By integrating the angular velocity, we can get a new posture, and the update formula satisfies: in, Indicates the new posture of the photoacoustic imaging probe, Indicates the posture at the previous moment. represents the new angular velocity, represents the angular velocity at the previous moment, is the time step.

[0042] The core of the posture control in this embodiment is to adjust the rotational acceleration of the robot arm through external torque feedback, such as the contact torque provided by the environment, so as to achieve posture adjustment. The change of posture is related to the interaction of external torque, damping, and stiffness matrix.

[0043] In another embodiment, adjusting the posture of the photoacoustic imaging probe according to the mechanical information of the photoacoustic imaging probe can also be achieved by the following steps: The rotation angle of the photoacoustic imaging probe is obtained according to the mechanical information.

[0044] In the embodiment, the rotation angle of the photoacoustic imaging probe is obtained according to the mechanical information, and satisfies the following formula: in, represents the X-axis rotation angle of the photoacoustic imaging probe, represents the Y-axis rotation angle of the photoacoustic imaging probe, represents the Z-axis rotation angle of the photoacoustic imaging probe, represents the moment component in the X-axis direction, represents the moment component in the Y-axis direction, represents the moment component in the Z-axis direction, represents the norm of the force acting on the photoacoustic imaging probe, Represents the distance from the point of force application to the center of rotation.

[0045] The norm of the force acting on the photoacoustic imaging probe satisfies: , , , They represent the three-dimensional components of the force acting on the photoacoustic imaging probe.

[0046] Furthermore, a new posture of the photoacoustic imaging probe is updated by the rotation angle.

[0047] The new posture of the photoacoustic imaging probe is updated by the rotation angle, satisfying the following formula: in, represents the updated photoacoustic imaging probe posture, represents the posture of the photoacoustic imaging probe at the previous moment, represents the rotation angle of the photoacoustic imaging probe, Represents the torque component that determines the direction of rotation.

[0048] S4. Using the photoacoustic imaging probe with updated posture, complete three-dimensional photoacoustic imaging of the target area.

[0049] In an embodiment, the imaging region is traversed step by step to ensure that the entire target region is covered, thereby completing three-dimensional photoacoustic imaging of the target region.

[0050] Furthermore, the minimum accuracy of each movement of the three-dimensional photoacoustic scanning is given by the following formula: Indicates the distance the probe moves in a single stroke. represents the speed of sound, represents the center frequency of the photoacoustic imaging probe.

[0051] See also Figure 2 , Figure 2 (a) represents the scanning method of the present invention, Figure 2 (b) represents the conventional scanning method. Figure 2 1 in the middle represents the photoacoustic imaging probe. Figure 2 2 in the middle represents the beam, Figure 2 3 represents the imaging target. The imaging target 3 refers to the part to be photoacoustically imaged in the target area. The photoacoustic imaging probe 1 emits a light beam 2 to the imaging target and collects feedback information for subsequent imaging. By comparison, it can be found that by adopting the method of the present invention, the probe can adjust its position and posture in real time during movement to ensure that the contact surface of the probe is in close contact with the skin surface, thereby avoiding the risk of missing the imaging target, especially when contacting non-flat parts, and accurately scanning each area that needs to be imaged; at the same time, since the contact surface of the probe always maintains a constant force fit with the imaging part, the consistency of the light flux at each imaging position is guaranteed, thereby avoiding the difference in light flux between different positions and ensuring the consistency of imaging quality; finally, the present invention can flexibly adapt to the scanning of curved or irregular surfaces, and is no longer subject to the physical limitations of the scanning part, breaking through the limitations of small-range scanning and only applicable to flat areas in traditional technologies.

[0052] See also Figure 3 In an embodiment, in order to efficiently execute a three-dimensional photoacoustic imaging method based on the two-dimensional contour of an imaging part provided by the present invention, the present invention further provides a three-dimensional photoacoustic imaging device based on the two-dimensional contour of an imaging part, and the device comprises: a two-dimensional camera, a multi-degree-of-freedom robotic arm, a photoacoustic probe, a laser coupler, a multi-wavelength laser, a digital delayed pulse synchronizer, a pulse synchronization trigger, an industrial computer, and a photoacoustic signal collector.

[0053] Two-dimensional camera: Take a picture of the imaging platform to obtain the two-dimensional contour of the tissue part. In this example, the two-dimensional camera used is an RGB camera.

[0054] Multi-DOF robotic arm: used to precisely control the position and posture of the photoacoustic probe at the imaging site, and output a trigger signal for data acquisition. In this example, a six-DOF robotic arm is used, which can obtain the spatial coordinates of the photoacoustic probe, including the three-dimensional position (x, y, z) and posture (rx, ry, rz). The high-level analog signal output by the robotic arm is 24V, which is used to trigger data acquisition. The robotic arm has a built-in six-dimensional force sensor, which can measure the force in three-dimensional space (x, y, z axis) and the corresponding torque (torque around the x, y, z axis) in real time. These force and torque data are used to monitor the force on the contact surface of the photoacoustic probe in real time and accurately adjust the position and posture of the photoacoustic probe.

[0055] Photoacoustic probe: used to receive the photoacoustic signal generated by the imaging target. In this example, the photoacoustic probe consists of a quartz optical fiber with a diameter of 1.5 mm, a B-ultrasound transducer, and an optical lens group. The photoacoustic probe can effectively receive the ultrasonic signal generated by laser excitation and convert it into image data for subsequent analysis.

[0056] Laser coupler: used to effectively transfer the output beam of the laser into the optical fiber, and transmit it to the photoacoustic probe through the optical fiber for subsequent photoacoustic imaging process.

[0057] Multi-wavelength laser: used as an excitation source in photoacoustic imaging, it stimulates tissue to produce photoacoustic effects by generating laser signals of different wavelengths. In this example, the laser used is a 100 Hz pulsed laser with an adjustable wavelength range of 532 nm to 1064 nm, which can provide laser outputs of different wavelengths.

[0058] Laser synchronizer: used to synchronize the oscillation and amplification stages of the laser to ensure that the laser outputs a stable beam.

[0059] Pulse synchronization trigger: used for unified timing control of pulse signals of different frequencies between devices and standard conversion of high-level signals. In this example, the pulse synchronization trigger receives pulse signals from the laser synchronizer and the multi-degree-of-freedom robotic arm, and after timing synchronization, it outputs a standard high-level signal to trigger the data acquisition system to collect photoacoustic signals.

[0060] Photoacoustic signal collector: used to collect photoacoustic signal data. In this example, the photoacoustic signal collector used is a 256-channel photoacoustic data collector.

[0061] Industrial computer: used to perform the control and processing tasks in the above method, responsible for controlling the force-controlled movement of the robotic arm, storing photoacoustic data, and displaying the 2D photoacoustic images generated during the scanning process in real time.

[0062] The device workflow includes: The industrial computer controls the two-dimensional camera to take two two-dimensional images with and without the target part, and performs image processing to extract the two-dimensional contour of the imaging part and plan the two-dimensional path; the industrial computer extracts the two-dimensional path and converts it into three-dimensional coordinates in the camera coordinate system; the industrial computer converts the three-dimensional coordinates into the position coordinates of the movement of the robotic arm; the industrial computer sends instructions to the robotic arm to control the photoacoustic probe to move and position according to the position coordinates. At the same time, the industrial computer analyzes the force data of the photoacoustic probe and provides real-time feedback to the robotic arm for posture adjustment; when the position and posture of the photoacoustic probe meet the expected conditions, the industrial computer data acquisition process is triggered. Since the robotic arm sends out an acquisition trigger signal, the signal triggers the photoacoustic signal collector through a pulse synchronization trigger and a laser synchronizer to ensure that the laser emission and data acquisition process are carried out synchronously, and the photoacoustic signal collector stores the real-time collected data in the industrial computer.

[0063] See also Figure 4 In an embodiment, in order to efficiently execute the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part provided by the present invention, the present invention also provides a three-dimensional photoacoustic imaging system based on the two-dimensional contour of the imaging part, including: an input device, an output device, a processor, and a memory, wherein the input device, the output device, the processor, and the memory are interconnected, and the memory contains program instructions, and the program instructions are used for the steps of the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part. The three-dimensional photoacoustic imaging system based on the two-dimensional contour of the imaging part of the present invention has a compact structure and stable performance, and can stably execute the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part of the present invention, further improving the overall applicability and practical application ability of the present invention.

[0064] In an embodiment, the processor may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. An input device may be used to obtain data information. An output device may be used to output the results obtained by storing program instructions contained in a computer program in a memory provided by the present invention. The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory.

[0065] In yet another alternative embodiment, see Figure 5 In order to efficiently perform the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part provided by the present invention, this embodiment also provides a three-dimensional photoacoustic imaging device based on the two-dimensional contour of the imaging part, such as Figure 5 Said, including: The memory 10 is used to store computer programs; the processor 20 is used to execute the computer programs to implement the above-mentioned three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part. The memory 10, the processor 20, the communication interface 31 and the communication bus 32. The memory 10, the processor 20, and the communication interface 31 all communicate with each other through the communication bus 32.

[0066] In an embodiment, the memory 10 is used to store one or more program instructions. The memory 10 may store program instructions for implementing the following functions: Extract the two-dimensional contour of the imaging part, and plan a two-dimensional moving path according to the two-dimensional contour; obtain the position coordinates of the movement of the robotic arm according to the two-dimensional moving path; adjust the position of the photoacoustic imaging probe based on the position coordinates, and adjust the posture of the photoacoustic imaging probe according to the mechanical information of the photoacoustic imaging probe; use the photoacoustic imaging probe with updated posture to complete three-dimensional photoacoustic imaging of the target area.

[0067] In one possible implementation, the memory 10 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, and at least one application required for a function, etc.; the data storage area may store data created during use. In addition, the memory 10 may include a read-only memory and a random access memory, and provide instructions and data to the processor. A portion of the memory may also include NVRAM. The memory stores an operating system and operating instructions, executable modules or data structures, or a subset thereof, or an extended set thereof, wherein the operating instructions may include various operating instructions for implementing various operations. The operating system may include various system programs for implementing various basic tasks and processing hardware-based tasks.

[0068] The processor 20 may be a central processing unit (CPU), an application specific integrated circuit, a digital signal processor, a field programmable gate array or other programmable logic device, and the processor 20 may be a microprocessor or any conventional processor, etc. The processor 20 may call a program stored in the memory 10. The communication interface 31 may be an interface of a communication module, and is used to connect with other devices or systems.

[0069] Of course, it should be noted that Figure 5 The above structure does not constitute a limitation on the three-dimensional photoacoustic imaging device based on the two-dimensional contour of the imaging part in this embodiment. In actual applications, the three-dimensional photoacoustic imaging device based on the two-dimensional contour of the imaging part may include Figure 5 More or fewer components as described, or combinations of certain components.

[0070] An embodiment further provides a storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the above-mentioned three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part are implemented.

[0071] The storage medium may include: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store program codes.

[0072] In summary, the present invention realizes full-coverage conformal three-dimensional photoacoustic imaging of the contour of the imaging part through a low-cost two-dimensional camera, solves the problems of inconsistent light flux distribution in the imaging plane in different target areas, the existence of imaging blind spots and limited imaging range due to the fixed orientation of the probe in the three-dimensional photoacoustic imaging technology based on photoacoustic tomography, and is further conducive to ensuring consistent light flux during the three-dimensional photoacoustic imaging process, realizing quantitative photoacoustic imaging of different parts of the human body, thereby ensuring the consistency of imaging conditions and the reliability of results, making the evaluation of vascular morphology and function more accurate, which is of great significance for the early diagnosis, evaluation and monitoring of vascular diseases.

[0073] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope recorded in the present invention.

Claims

1. A three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part, characterized in that: The following steps are involved: Extracting a two-dimensional contour of the imaging part, and planning a two-dimensional moving path according to the two-dimensional contour; According to the two-dimensional moving path, obtaining the position coordinates of the robot arm movement; adjusting the position of the photoacoustic imaging probe based on the position coordinates, and adjusting the posture of the photoacoustic imaging probe according to the mechanical information of the photoacoustic imaging probe; The photoacoustic imaging probe with updated posture is used to complete three-dimensional photoacoustic imaging of the target area.

2. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 1, characterized in that: The two-dimensional contour of the extracted imaging part satisfies the following formula: in, represents the difference image, Represents the pixel value of the background image, Represents the pixel value of the image containing the target part, Represents absolute value operation.

3. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 1, characterized in that: The two-dimensional moving path is planned according to the two-dimensional contour, satisfying the following formula: in, Indicates The coordinates of the sampling path points, represents the set of target contour points, Represents the total number of contour points, Indicates the number of path points you want to sample.

4. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 1, characterized in that: The step of obtaining the position coordinates of the robot arm movement according to the two-dimensional moving path comprises the following steps: According to the two-dimensional moving path, obtaining three-dimensional coordinates in a camera coordinate system; The three-dimensional coordinates are used to obtain the position coordinates of the robot arm movement.

5. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 4, characterized in that: According to the two-dimensional moving path, the three-dimensional coordinates in the camera coordinate system are obtained, which satisfies the following formula: in, , Represents the coordinates of the pixel points of the two-dimensional image in the two-dimensional moving path, represents the focal length of the camera, represents the position of the camera optical axis projection on the image plane, represents the vertical distance from the camera to the imaging platform, Represents the coordinates of the pixel in the camera coordinate system.

6. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 4, characterized in that: The three-dimensional coordinates are used to obtain the position coordinates of the robot arm movement, satisfying the following formula: in, , , represents the coordinates of the robot base, , , Represents the three-dimensional coordinates in the camera coordinate system, Represents the rotation matrix of the camera coordinate system relative to the robot coordinate system, Represents the translation vector of the camera coordinate system relative to the robot coordinate system.

7. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 1, characterized in that: The step of adjusting the position of the photoacoustic imaging probe based on the position coordinates comprises the following steps: According to the position coordinates, obtaining the displacement acceleration of the photoacoustic imaging probe; Calculating a new displacement velocity using the displacement acceleration; An updated position of the photoacoustic imaging probe is calculated according to the new displacement velocity.

8. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 7, characterized in that: The displacement acceleration of the photoacoustic imaging probe is obtained according to the position coordinates, satisfying the following formula: in, represents the displacement acceleration of the photoacoustic imaging probe, represents the mass matrix, represents the contact force between the probe and the skin, represents the damping matrix, represents the expected speed, represents the speed at the previous moment, represents the stiffness matrix, represents the desired target position, Indicates the position at the previous moment.

9. The three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to claim 1, characterized in that: The step of adjusting the posture of the photoacoustic imaging probe by using the mechanical information of the photoacoustic imaging probe comprises the following steps: According to the mechanical information, obtaining the rotational acceleration of the robotic arm; Obtaining the angular velocity of the robotic arm through the rotational acceleration; The new posture of the photoacoustic imaging probe is obtained by using the angular velocity.

10. A three-dimensional photoacoustic imaging system based on the two-dimensional contour of the imaging part, characterized in that: The three-dimensional photoacoustic imaging system based on the two-dimensional contour of the imaging part comprises: an input device, an output device, a processor, and a memory, wherein the input device, the output device, the processor, and the memory are interconnected, and the memory comprises program instructions, and the program instructions are used to execute the three-dimensional photoacoustic imaging method based on the two-dimensional contour of the imaging part according to any one of claims 1 to 9.

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