Endoscopic OCT imaging correction device and method

Abstract

The application provides an imaging correction device and method for endoscopic OCT, wherein the device is composed of an OCT imaging catheter and a rotating and retracting driving assembly, a single-mode optical fiber, a self-focusing lens and a micro-mirror are sequentially arranged in the catheter, and a disposable sterile sheath is used in cooperation; the driving assembly comprises a synchronous rotating motor, a retracting mechanism and a high-resolution angle encoder, the angle encoder signal is linked with an external FPGA and a high-speed acquisition card through a trigger circuit, equal-angle triggering and data synchronization of A lines are realized, equal-angle resampling is performed on the collected data, and a sub-pixel registration algorithm based on block matching is provided to compensate for NURD distortion caused by respiratory jitter or friction between the spring and the sheath. Without reducing the axial / radial resolution, the application significantly improves the circumferential uniformity and suppresses deformation artifacts, has a simple structure, controllable cost, strong real-time performance and easy integration, and is suitable for stable imaging of a proximal driving endoscopic OCT system in clinical and scientific research.

Description

Technical Field

[0001] This invention relates to the field of medical image processing and endoscopic OCT imaging technology, and particularly to an imaging correction device and an imaging correction method for endoscopic OCT. Background Technology

[0002] Optical coherence tomography (OCT) is a high-resolution imaging technique based on low-coherence interference, which has been widely used for the microstructural observation of cavities such as ophthalmology, cardiovascular, and digestive tract. To meet the needs of minimally invasive clinical procedures, clinical endoscopic OCT typically employs a working mode of proximal motor rotation—distal catheter scanning and simultaneous retraction. Orientation information is obtained through rotation, and three-dimensional information is obtained through retraction, forming helical volume data.

[0003] In proximal drive structures, image drift manifests as a low-frequency, cumulative overall displacement over time: the suture lines (0° / 360°) in the unfolded image gradually shift, and the longitudinal texture becomes tilted. This primarily stems from the elastic hysteresis of the drive catheter and the inability to precisely match the speed of the rotary motor. Jitter drift is more of a global offset, causing angular suture misalignment and layer mismatch, thus affecting the stable measurement of geometric quantities such as cavity diameter and area, and multi-frame fusion. Unlike drift jitter, non-uniform rotational distortion (NURD) is prone to occur due to the friction of the slip ring of the drive spring and the dry friction between the catheter and the disposable sterile sheath. NURD manifests as unequal intervals in azimuth angle sampling, local compression or stretching, leading to geometric distortion of the image. When the subject experiences micro-movements due to respiration, cardiac activity, or endoscopic procedures, these distortions are further amplified, directly affecting the accuracy of cavity boundary measurement, lesion localization, and subsequent quantitative analysis.

[0004] Therefore, in proximal-driven scenarios of endoscopic OCT, neither simple software post-processing nor simple hardware isoangular triggering can simultaneously achieve geometric accuracy, real-time performance, and system integration without sacrificing axial / radial resolution. A correction scheme is urgently needed: on the one hand, it requires achieving isoangular synchronous sampling to suppress azimuth non-uniformity at its source; on the other hand, on the processing side, registration and compensation for residual NURD are needed to improve circumferential uniformity, concentricity, and the stability of volume reconstruction, providing a reliable foundation for accurate intracavitary measurements and subsequent functional imaging. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in the aforementioned technologies. Therefore, the first objective of this invention is to propose an imaging correction device for endoscopic OCT, which uses an angle encoder for triggering, an FPGA and a high-speed acquisition card to achieve isoangular triggering and data synchronization along the A-line, and employs isoangular resampling and block-matching subpixel registration on the processing side to compensate for residual NURD and slow drift, thereby obtaining more stable imaging results.

[0006] The second objective of this invention is to propose an imaging correction method for endoscopic OCT.

[0007] To achieve the above objectives, a first aspect of the present invention provides an imaging correction device for endoscopic OCT, comprising: an OCT imaging catheter for acquiring OCT echo signals; a rotation and retraction drive assembly including a rotary motor, a retraction mechanism, and an angle encoder, wherein the rotary motor and the retraction mechanism drive the OCT imaging catheter to rotate and retract synchronously, and the rotary motor and the angle encoder are coaxially arranged; a trigger acquisition module including a trigger circuit, an external FPGA, and a data acquisition card, wherein the angle encoder outputs an angle pulse signal at each preset isoangular step, which drives the external FPGA to output a trigger signal and controls the data acquisition card to acquire OCT echo signals to obtain an A-line data sequence with angle timestamps; an image processing module performing isoangular resampling on the A-line data sequence to obtain an isoangular A-line sequence, and generating an OCT image frame based on the isoangular A-line sequence; and an image correction module performing block-matching subpixel registration on each OCT image frame to obtain a corrected OCT image.

[0008] The imaging correction device for endoscopic OCT proposed in this invention has the following advantages: it achieves isoangular triggering and data synchronization of the A-line through angle encoder triggering, FPGA and high-speed acquisition card, and compensates for residual NURD and slow drift by isoangular resampling and block matching subpixel registration on the processing side, thereby obtaining more stable imaging results.

[0009] In addition, the imaging correction device for endoscopic OCT according to the above embodiments of the present invention may also have the following additional technical features:

[0010] Optionally, the OCT imaging catheter is provided with a single-mode optical fiber, a self-focusing lens and a micromirror in sequence, and works with a disposable sterile sheath to achieve clinical sterilization and replacement.

[0011] Optionally, the external FPGA is also used for de-jittering and timestamp calibration, and to mark the timestamp of each trigger signal to establish an "angle-time" mapping relationship.

[0012] Optionally, the image processing module performs isoangular resampling based on the A-line data sequence to obtain an isoangular A-line sequence, including: establishing an angle-time interpolation model; interpolating the A-line data sequence to the angle-time interpolation model according to the "angle-time" mapping relationship, so as to map the non-uniform time sampling caused by non-uniform rotation to an isoangular A-line sequence.

[0013] Optionally, the image correction module performs subpixel registration of block matching for each frame of OCT image to obtain a corrected OCT image, including: if the current frame's OCT image is not the first frame, then dividing the current frame's OCT image into multiple sectors in the azimuth direction; performing block matching on each sector and the sector corresponding to the reference frame, calculating similarity through normalized cross-correlation, and obtaining confidence using peak-to-sidelobe ratio; when the confidence is higher than a preset threshold, obtaining the azimuth displacement of the sector using subpixel interpolation; when the confidence is lower than the preset threshold, setting the sector displacement to zero or replacing it with neighborhood interpolation results; fusing the azimuth displacement of each sector into a global displacement field through spline interpolation / smoothing constraints, and updating the compensation parameters together with the cumulative displacement of the previous frame to obtain the corrected OCT image.

[0014] Optionally, the rotational retraction drive component is a proximal torsional retraction structure, whose retraction speed and rotation speed can be set independently to achieve helical volume data acquisition and maintain synchronization with isoangular triggering.

[0015] Optionally, the disposable sterile sheath is provided with a low refractive index window at its end to reduce interface reflection, and a low friction liner is provided between the catheter and the sheath to reduce friction-induced non-uniform rotational distortion.

[0016] Optionally, the rotation retraction drive assembly further includes an optical fiber interface, a clamping platform, an optoelectronic slip ring, and a belt. The proximal end of the OCT imaging catheter is connected to the optical path via the optical fiber interface and is guided into the hollow channel of the optoelectronic slip ring via the clamping platform. A rotary motor drives the optoelectronic slip ring to rotate via the belt, and an angle encoder is coaxially mounted with the optoelectronic slip ring and outputs an angle pulse signal. The retraction mechanism carries and drives the clamping platform and the OCT imaging catheter to achieve axial retraction.

[0017] Optionally, the angle encoder is an incremental high-resolution encoder with a resolution of 5000 rpm.

[0018] To achieve the above objectives, a second aspect of the present invention provides an imaging correction method for endoscopic OCT, applied to the imaging correction device for endoscopic OCT as described in any of the first aspects, comprising the following steps: outputting an angle pulse signal once according to a preset isoangular step under rotational retraction drive; outputting a trigger signal according to the angle pulse signal to acquire OCT echo signals according to the trigger signal to obtain an A-line data sequence with angle timestamps; performing isoangular resampling according to the A-line data sequence to obtain an isoangular A-line sequence, and generating an OCT image frame according to the isoangular A-line sequence; performing subpixel registration of block matching on each OCT image frame to obtain a corrected OCT image. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the rotation retraction drive assembly according to an embodiment of the present invention;

[0020] Figure 2 This is a block diagram of an imaging correction device for endoscopic OCT according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic flowchart of an imaging correction method for endoscopic OCT according to an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of a timing logic design according to an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of equal-angle acquisition according to an embodiment of the present invention;

[0024] Figure 6 A schematic diagram of a block-matching-based registration algorithm according to an embodiment of the present invention;

[0025] Figure 7 This is a comparison diagram showing the data before and after correction according to an embodiment of the present invention.

[0026] Label Explanation:

[0027] 1. Retraction mechanism; 2. Fiber optic interface; 3. Clamping platform; 4. Rotary motor; 5. Photoelectric slip ring; 6. Belt; 7. Angle encoder; 10. OCT imaging catheter; 20. Rotation and retraction drive assembly; 30. Trigger acquisition module; 40. Image processing module; 50. Image correction module. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0030] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0031] like Figure 1-2 As shown, the imaging correction device for endoscopic OCT includes: an OCT imaging catheter 10, a rotation and retraction drive assembly 20, a trigger acquisition module 30, an image processing module 40, and an image correction module 50.

[0032] The OCT imaging catheter 10 is used to acquire OCT echo signals. The rotation and retraction drive assembly 20 includes a rotary motor 4, a retraction mechanism 1, and an angle encoder 7. The rotary motor 4 and the retraction mechanism 1 drive the OCT imaging catheter 10 to rotate and retract synchronously. The rotary motor 4 and the angle encoder 7 are coaxially arranged. The trigger acquisition module 30 includes a trigger circuit, an external FPGA, and a data acquisition card. The angle encoder 7 outputs an angle pulse signal at each preset equal-angle step. The trigger circuit drives the external FPGA to output a trigger signal and controls the data acquisition card to acquire OCT echo signals to obtain an A-line data sequence with angle timestamps. The image processing module 40 performs equal-angle resampling based on the A-line data sequence to obtain an equal-angle A-line sequence and generates an OCT image frame based on the equal-angle A-line sequence. The image correction module 50 performs block matching sub-pixel registration on each OCT image frame to obtain a corrected OCT image.

[0033] As an example, the OCT imaging catheter 10 is provided with a single-mode optical fiber, a self-focusing lens and a micromirror in sequence, and works with a disposable sterile sheath to achieve clinical sterilization and replacement.

[0034] As an example, a low-refractive-index window is provided at the end of the disposable sterile sheath to reduce interface reflection, and a low-friction liner is provided between the catheter and the sheath to reduce friction-induced non-uniform rotational distortion.

[0035] As an example, the rotational retraction drive component 20 is a proximal torsional retraction structure, and its retraction speed and rotation speed can be set independently to achieve helical volume data acquisition and keep it synchronized with the isoangular trigger.

[0036] Specifically, such as Figure 1 As shown, a retraction mechanism 1 is provided in sequence along the retraction direction: it is used to drive the endoscopic OCT imaging catheter 10 to make axial linear motion. It is preferably an electric linear module or a lead screw platform, which supports an adjustable speed of 0.1–20 mm / s and has an origin / limit switch to ensure the accuracy and repeatability of the retraction step distance of volume acquisition.

[0037] Fiber optic interface 2: Used to connect the optical signal output / returned from the system host to the rotating end conduit. It is preferred to use standard interfaces such as FC / SC or custom coaxial fiber optic connectors, and to use stress relief structure to avoid bending loss.

[0038] Clamping platform 3: Used to clamp and position the proximal end of the OCT imaging catheter 10 or the drive spring / rotor, providing height and angle fine-tuning to achieve axis coaxiality control.

[0039] Rotary motor 4: As a near-end rotational drive source, the drive frequency range is 100–8000 rpm; its output shaft is connected to the input end of the photoelectric slip ring 5 through the belt 6 to realize flexible transmission and isolate minor eccentricity and vibration.

[0040] Optical slip ring 5: Used to achieve reliable transmission of optical / electrical signals while rotating. The optical channel is connected to the optical fiber in the conduit, and the electrical channel is used for power supply and signal output of the motor / encoder / sensor, ensuring low loss and low jitter during rotation.

[0041] Belt 6: Adopting a synchronous belt / pulley structure, it smoothly transmits the torque of the rotary motor 4 to the photoelectric slip ring 5 / angle encoder 7, and has the functions of vibration reduction, buffering and speed ratio adjustment, reducing transient speed fluctuations.

[0042] Angle encoder 7: Installed on the coaxial end or coaxial system of photoelectric slip ring 5, used to output A / B / Z channel angle pulses. The angle pulse signal of angle encoder 7 is sent to the external FPGA and high-speed acquisition card through the trigger circuit to realize the equal angle triggering and timestamp synchronization of line A; when the speed of rotating motor 4 is disturbed or the transmission elasticity changes, the equal angle consistency of azimuth sampling can still be maintained.

[0043] During assembly, the proximal end of the OCT imaging catheter 10 is connected to the optical path of the system host via fiber optic interface 2, and is guided into the hollow channel of the photoelectric slip ring 5 through a fixed clamping platform 3. The rotary motor 4 drives the photoelectric slip ring 5 to rotate via belt 6. The angle encoder 7 is coaxially mounted with the photoelectric slip ring 5 and outputs angle pulse signals. The retraction mechanism 1 carries and drives the clamping platform 3 and the OCT imaging catheter 10 to achieve axial retraction. This layout makes the rotation and retraction degrees of freedom independent of each other, and at the same time, the angle encoder 7 is synchronized with the external FPGA / acquisition card through equal angle triggering to achieve source-end angle consistency.

[0044] In addition, the angle encoder 7 is a key synchronization component of this device, preferably an incremental high-resolution encoder with a resolution of 5000 rpm. The angle encoder 7 is synchronized with the rotating shaft via belt 6 or coupling, and is coaxially mounted on the shaft system on one side of the photoelectric slip ring 5. It is only used for angle measurement and triggering and does not undertake the function of conduit passage or rotation interface. The A / B quadrature pulse and Z index signal output by the angle encoder 7 are sent to the FPGA and high-speed acquisition card through isolation and shaping trigger circuit. It generates A-line equal angle triggering according to the preset angle and records the hardware timestamp. At the same time, it can establish angle-time mapping and monitor angular velocity disturbances through frequency multiplication / subdivision. To reduce jitter and electromagnetic interference, the angle encoder 7, rotating motor 4, and photoelectric slip ring 5 share a rigid base and adopt a shielded grounding and belt vibration isolation arrangement, thereby improving the stability and repeatability of equal angle triggering.

[0045] As an example, the external FPGA is also used for de-jittering and timestamp calibration, and to mark the timestamp of each trigger signal to establish an "angle-time" mapping relationship.

[0046] As one embodiment, the image processing module 40 performs iso-angle resampling on the A-line data sequence to obtain an iso-angle A-line sequence, including: establishing an angle-time interpolation model; interpolating the A-line data sequence to the angle-time interpolation model according to the "angle-time" mapping relationship, so as to map the non-uniform time sampling caused by non-uniform rotation to an iso-angle A-line sequence.

[0047] Specifically, such as Figure 4 As shown, the zero-reset signal of angle encoder 7 marks the start of each revolution. The zero-reset signal of angle encoder 7 fluctuates like a sine wave, with one peak and trough constituting one cycle. Within each revolution, angle encoder 7 uniformly generates M equal-angle triggers with a step angle of 5000 / 360°. The frequency of the sweep frequency light source trigger signal is fixed at N, determined by the sweep frequency period. An external FPGA receives data from line A. When the accumulated data reaches a set number, the external FPGA sends an enable signal P to acquire the signal at the current position. After angle encoder 7 completes one revolution, it generates a frame synchronization signal and resets the angle count, entering the next revolution for acquisition. This timing ensures consistent azimuth sampling regardless of changes in instantaneous angular velocity.

[0048] Specifically, such as Figure 5 As shown, a stable data acquisition process is achieved by coordinating the light source trigger signal and the angle encoder 7 equal angle trigger signal through an external FPGA. When the rotary motor 4 rotates at normal speed, the trigger signal of the light source corresponds strictly to the equiangular trigger signal of the angle encoder 7. The FPGA generates a synchronous enable signal accordingly, so that the trigger of the light source and the acquisition time slot are perfectly aligned, forming a seamless timing registration and ensuring uniform sampling of a fixed number of lines per revolution. When the rotation speed is slower, the time interval between adjacent equiangular trigger signals is lengthened, while the trigger rate of the light source remains unchanged. The FPGA continues to generate a specified number of trigger signals by accumulating by angle. Since the trigger interval between adjacent light sources may become shorter than the equiangular interval, resulting in false triggers that are too close, the FPGA will discard these false triggers that are too close to avoid overly dense sampling. Only the valid triggers that meet the minimum sampling time slot requirements will be retained, ultimately ensuring that a fixed number of lines is maintained per revolution and avoiding data redundancy. When the rotation speed is faster, the time interval between adjacent equiangular trigger signals becomes shorter, but the trigger rate of the light source remains unchanged. When the signal from the angle encoder 7 arrives, the FPGA checks whether the specified angle count has been accumulated in the previous interval. If the count is less than the specified number, the acquisition cannot be triggered and the current acquisition is skipped. This mechanism prevents insufficient sampling and ensures stable acquisition quality.

[0049] As one embodiment, the image correction module 50 performs subpixel registration of block matching on each frame of OCT image to obtain a corrected OCT image, including: if the current frame's OCT image is not the first frame, then the current frame's OCT image is divided into multiple sectors in the azimuth direction; block matching is performed on each sector and the sector corresponding to the reference frame, similarity is calculated through normalized cross-correlation, and confidence is obtained using peak-to-sidelobe ratio; when the confidence is higher than a preset threshold, the azimuth displacement of the sector is obtained using subpixel interpolation; when the confidence is lower than the preset threshold, the sector displacement is set to zero or replaced by neighborhood interpolation results; the azimuth displacement of each sector is fused into a global displacement field through spline interpolation / smoothing constraints, and the compensation parameters are updated together with the cumulative displacement of the previous frame to obtain the corrected OCT image.

[0050] Specifically, such as Figure 6As shown, after acquiring the raw image data from the endoscopic OCT, the system first determines whether it is the first frame. If it is, it saves it as the reference frame and proceeds directly to the next frame for processing. If it is not the first frame, the current frame is divided into multiple sectors in the azimuth direction. Block matching correlation calculation is performed on each sector and the corresponding sector of the reference frame, and the confidence index of the sector is obtained by using the peak-to-sidelobe ratio correlation peak. When the confidence is higher than the threshold, the azimuth displacement of the sector is obtained using sub-pixel interpolation; when the confidence is lower than the threshold, the sector displacement is set to zero or replaced by the neighborhood interpolation result. Subsequently, the displacements of each sector are fused into a global displacement field through spline interpolation / smoothing constraints, and the drift and NURD compensation parameters are updated together with the cumulative displacement of the previous frame. The system performs geometric resampling / distortion correction on the current frame based on this displacement field, and performs stitching smoothing at the sector boundaries. The resulting corrected image serves as the output and can also be updated as a new reference frame for registration in the next frame, thereby achieving continuous and stable correction along the pullback direction.

[0051] Specifically, such as Figure 7 As shown, the image on the left is the result of acquisition in the uncorrected state, exhibiting obvious non-uniform rotational distortion characteristics: uneven distribution of radial stripes, dense and distorted stripes in some areas, blurred edges, and angular offsets, resulting in imaging distortion and loss of detail. The image on the right is the result after correction using this device. Through synchronous acquisition at equal angles and real-time NURD compensation, the stripes are evenly distributed, the angles are precisely aligned, and the overall structure is clear and symmetrical, significantly improving the fidelity and resolution of the endoscopic OCT image. This comparison verifies the robustness of the device in dynamic rotational environments and effectively suppresses distortion caused by rotational speed fluctuations.

[0052] In other words, as a specific embodiment, the angle encoder 7 (such as an incremental high-resolution encoder with a resolution of 5000 lines / revolution) is coaxially mounted with the rotating shaft, outputting A / B quadrature pulses (for angle measurement) and a Z index signal (zeroing mark per revolution). For each preset angular step (e.g., 5000 steps per 360° revolution, each step 0.072°), the angle encoder 7 outputs an angle pulse signal, which is sent to the FPGA via an isolated trigger circuit. After receiving the angle pulse signal from the angle encoder 7, the FPGA generates an A-line angular trigger signal according to the preset angle step (e.g., every 0.072°), synchronously triggering the light source frequency sweep and the high-speed acquisition card; each trigger signal is marked with a hardware timestamp, establishing an "angle-time" mapping relationship; even if the motor speed fluctuates (e.g., too fast / too slow), the FPGA still ensures a fixed number of triggers per revolution (e.g., 5000 times) by accumulating angle counts, avoiding overly dense or insufficient sampling. The high-speed acquisition card responds to the FPGA's trigger signal, acquiring one OCT A-line data point (containing optical echo information of radial tissue) each time it is triggered. During each rotation, the acquisition card collects a total of 5000 iso-angle A-lines (consistent with the 7 steps of the angle encoder), with each A-line accompanied by an angle timestamp. The image processing module 40 uses an "angle-time" mapping to interpolate the original time-domain sampled data to an iso-angle grid (keeping the radial resolution unchanged); the iso-angle resampled A-lines are arranged in ascending order of azimuth angle, forming a two-dimensional frame structure of "azimuth (0°~360°) × radial (depth)," i.e., a single-frame OCT image. Sub-pixel registration with block matching is performed on the single-frame OCT image. Along the retracement direction (proximal to distal), a corrected image is generated after each rotation, continuously acquiring three-dimensional spiral volume data (multi-frame corrected image sequence) to achieve stable imaging in endoscopic OCT.

[0053] In summary, the imaging correction device for endoscopic OCT provided by the embodiments of the present invention solves the problems of uneven azimuth sampling, geometric distortion, and decreased concentricity caused by angular velocity fluctuations and transmission elasticity in traditional proximal-driven endoscopic OCT. This device uses an angle encoder for triggering, and an FPGA and high-speed acquisition card to achieve isoangular triggering and data synchronization along the A-line. On the processing side, isoangular resampling and block-matching subpixel registration are used to compensate for residual NURD and slow drift. This results in more stable imaging results, providing reliable support for clinical interventional navigation.

[0054] To achieve the above embodiments, such as Figure 3 As shown in the figure, this invention also proposes an imaging correction method for endoscopic OCT, comprising the following steps:

[0055] S101, under the drive of rotation and retraction, outputs an angle pulse signal once according to the preset equal angle step.

[0056] S102 outputs a trigger signal based on the angle pulse signal to acquire the OCT echo signal based on the trigger signal, so as to obtain the A-line data sequence with angle timestamp.

[0057] S103, perform iso-angle resampling based on the A-line data sequence to obtain an iso-angle A-line sequence, and generate an OCT image based on the iso-angle A-line sequence.

[0058] S104, perform subpixel registration of block matching for each frame of OCT image to obtain the corrected OCT image.

[0059] It should be noted that the device used in the endoscopic OCT imaging correction method of this embodiment is the aforementioned endoscopic OCT imaging correction device. Therefore, the explanation and description of the aforementioned embodiment of the endoscopic OCT imaging correction device also applies to the endoscopic OCT imaging correction method of this embodiment, and will not be repeated here.

[0060] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0061] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0062] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0063] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0064] It should be noted that any reference signs placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0065] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0067] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0068] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0069] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of 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. "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.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An imaging correction device for endoscopic OCT, characterized in that, include: OCT imaging catheter, which is used to acquire OCT echo signals; A rotational retraction drive assembly includes a rotary motor, a retraction mechanism, and an angle encoder. The rotary motor and the retraction mechanism drive the OCT imaging catheter to rotate and retract synchronously. The rotary motor and the angle encoder are coaxially arranged. The trigger acquisition module includes a trigger circuit, an external FPGA, and a data acquisition card. The angle encoder outputs an angle pulse signal once for each preset equal angle step. The trigger circuit drives the external FPGA to output a trigger signal and controls the data acquisition card to acquire OCT echo signals to obtain an A-line data sequence with angle timestamps. An image processing module performs iso-angle resampling on the A-line data sequence to obtain an iso-angle A-line sequence, and generates an OCT image frame based on the iso-angle A-line sequence. An image correction module performs block matching subpixel registration on each frame of the OCT image to obtain a corrected OCT image. The image correction module performs block-matching sub-pixel registration on each frame of the OCT image to obtain a corrected OCT image, including: If the OCT image of the current frame is not the first frame, then the OCT image of the current frame is divided into multiple sectors in the orientation direction; For each sector, block matching is performed with the sector corresponding to the reference frame. The similarity is calculated by normalized cross-correlation, and the confidence is obtained by peak sidelobe ratio. When the confidence level is higher than a preset threshold, the azimuth displacement of the sector is obtained by subpixel interpolation. When the confidence level is lower than a preset threshold, the sector displacement is set to zero or replaced by the neighborhood interpolation result. The azimuth displacement of each sector is fused into a global displacement field through spline interpolation / smoothing constraints, and the compensation parameters are updated together with the cumulative displacement of the previous frame to obtain the corrected OCT image.

2. The imaging correction device for endoscopic OCT as described in claim 1, characterized in that, The OCT imaging catheter is sequentially equipped with a single-mode optical fiber, a self-focusing lens, and a micromirror, and works in conjunction with a disposable sterile sheath to achieve clinical sterilization and replacement.

3. The imaging correction device for endoscopic OCT as described in claim 1, characterized in that, The external FPGA is also used for de-jittering and timestamp calibration, and marks each trigger signal with a timestamp to establish an "angle-time" mapping relationship.

4. The imaging correction device for endoscopic OCT as described in claim 3, characterized in that, The image processing module performs isoangular resampling based on the A-line data sequence to obtain an isoangular A-line sequence, including: Establish an angle-time interpolation model; The A-line data sequence is interpolated to the angle-time interpolation model based on the angle-time mapping relationship, so as to map the non-uniform time sampling caused by non-uniform rotation into a uniform angle A-line sequence.

5. The imaging correction device for endoscopic OCT as described in claim 1, characterized in that, The rotational retraction drive component is a proximal torsional retraction structure, and its retraction speed and rotation speed are set independently to achieve helical volume data acquisition and keep it synchronized with the isoangular trigger.

6. The imaging correction device for endoscopic OCT as described in claim 2, characterized in that, The disposable sterile sheath is provided with a low refractive index window at the end to reduce interface reflection, and a low friction liner is provided between the catheter and the sheath to reduce friction-induced non-uniform rotational distortion.

7. The imaging correction device for endoscopic OCT as described in claim 1, characterized in that, The rotation retraction drive assembly also includes an optical fiber interface, a clamping platform, an optoelectronic slip ring, and a belt. The proximal end of the OCT imaging catheter is connected to the optical path via the optical fiber interface and is guided into the hollow channel of the optoelectronic slip ring via the clamping platform. The rotary motor drives the optoelectronic slip ring to rotate via the belt. The angle encoder is coaxially mounted with the optoelectronic slip ring and outputs an angle pulse signal. The retraction mechanism carries and drives the clamping platform and the OCT imaging catheter to achieve axial retraction.

8. The imaging correction device for endoscopic OCT as described in claim 1, characterized in that, The angle encoder is an incremental high-resolution encoder with a resolution of 5000 rpm.

9. An imaging correction method for endoscopic OCT, characterized in that, The imaging correction device applied to the endoscopic OCT according to any one of claims 1-8, the method comprising the following steps: Under the rotational retraction drive, an angle pulse signal is output once for each preset equal angle step; A trigger signal is output based on the angle pulse signal to acquire the OCT echo signal based on the trigger signal, so as to obtain the A-line data sequence with angle timestamp; An isoangular resampling is performed on the A-line data sequence to obtain an isoangular A-line sequence, and an OCT image is generated based on the isoangular A-line sequence. Subpixel registration with block matching is performed on each frame of the OCT image to obtain the corrected OCT image.

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