A CBCT system and method for dynamic human motion imaging

Abstract

The application relates to the technical field of medical imaging equipment, and discloses a CBCT system and method for dynamic human body motion imaging. The system comprises parallel double sliding rails and an integrally formed rigid inverted U-shaped frame bridging the two; an X-ray source and a detector are fixed to the two sides of the frame and keep the source-detector geometric relationship constant; a driving mechanism drives the frame to follow the sliding rails, so that a target anatomical region is kept at the center of the imaging field of view; a projection angle modulation mechanism on the frame makes the X-ray source and / or the detector rotate around the scanning region to form multi-angle cone beam projection; a controller combines position, speed and gait phase sensors to implement delay compensation follow-up, triggers pulse exposure at a preset gait phase, and records the track pose and the rotation angle for motion correction and three-dimensional / four-dimensional reconstruction. The application reduces synchronization error and geometric deviation by means of a rigid integrated structure, and is suitable for motion medical research by taking into account image quality and low dose.

Description

Technical Field

[0001] This invention relates to the field of medical imaging equipment technology, and in particular to a cone-beam computed tomography (CBCT) system and method for dynamic human motion imaging. Background Technology

[0002] Traditional CBCT imaging systems typically acquire images of static or quasi-static subjects, requiring the subject to maintain a fixed posture during the scan to ensure consistency of projection data and image reconstruction quality. However, in fields such as sports medicine, rehabilitation assessment, orthopedic functional evaluation, and biomechanical research, it is necessary to acquire three-dimensional dynamic image data of the human body in natural or controlled movement states such as walking, weight-bearing, climbing stairs, and squatting.

[0003] Currently available dynamic imaging or tracking imaging solutions typically rely on structures such as robotic arms, multi-degree-of-freedom supports, left / right split source / detector drives, or mobile chassis to achieve motion acquisition. These structures may be affected by structural flexibility, transmission backlash, synchronization control residuals, and ground repetitive positioning errors during large-scale or high-frequency tracking, making it difficult to maintain consistent source-detector relative geometry, scanning trajectory, and projection timing over long periods. Furthermore, some solutions have limited effective travel, attitude adaptation capabilities, and low-dose phase gating capabilities, making it difficult to simultaneously achieve complete motion cycle coverage and high-quality cone-beam reconstruction.

[0004] Furthermore, when the subject moves along the motion path and the imaging frame moves simultaneously, the longitudinal displacement of the imaging frame, the projection angles of the X-ray source and detector, and the position and orientation of the target anatomical region may all change over time, collectively affecting the imaging geometry corresponding to each cone-beam projection frame. Meanwhile, from the time the target's motion state is detected by the sensor to the actual X-ray exposure, there are system delays caused by sensor sampling, data transmission, control calculation, drive response, and exposure triggering. If the imaging frame is controlled solely based on the currently detected target position, the imaging field of view at the exposure time may deviate from the actual position of the target anatomical region. On the other hand, grouping projections of different motion cycles solely based on the motion phase cannot completely eliminate the impact of differences in target position and orientation between different cycles on projection consistency; when some projections are unusable due to positional deviations, motion phase deviations, geometric errors, or safety interlocks, the projection angles required for reconstruction may be missing.

[0005] Therefore, a CBCT system with stable structure, controllable stroke, easy scene switching, and the ability to coordinate follow-up control and multi-angle projection acquisition is needed to improve geometric stability, acquisition integrity, and reconstruction consistency under natural human movement. Summary of the Invention

[0006] This invention provides a CBCT system and method for dynamic human motion imaging, in order to overcome the shortcomings of the prior art.

[0007] The present invention provides a CBCT system for dynamic human motion imaging, comprising a first slide rail and a second slide rail arranged in parallel, an inverted U-shaped frame spanning between the first slide rail and the second slide rail, an X-ray source and a detector respectively fixed at relative positions on the two side walls of the inverted U-shaped frame, a drive mechanism capable of driving the inverted U-shaped frame to slide along the first slide rail and the second slide rail, a sensor for sensing the position and / or velocity of the subject, and a controller communicatively connected to the sensor, the drive mechanism, the X-ray source, and the detector.

[0008] In one embodiment, the present invention provides a CBCT system for dynamic human motion imaging, comprising a first slide rail and a second slide rail arranged in parallel, an integrally formed rigid inverted U-shaped frame spanning the first slide rail and the second slide rail, an X-ray source and a detector respectively fixed to the opposite positions of the two side walls of the inverted U-shaped frame, a drive mechanism for driving the inverted U-shaped frame to slide along the first slide rail and the second slide rail, a projection angle modulation mechanism disposed on the inverted U-shaped frame, a sensor for sensing the position, velocity and / or gait phase of the subject, and a controller communicatively connected to the sensor, the drive mechanism, the projection angle modulation mechanism, the X-ray source and the detector; wherein, the inverted U-shaped frame is used to maintain a constant relative geometric relationship between the X-ray source and the detector, and the controller performs delay-compensated follow-up control based on the sensor output and triggers multi-angle cone-beam projection acquisition for three-dimensional / four-dimensional reconstruction.

[0009] In one implementation, the controller predicts the target position at the actual exposure time of the cone-beam projection frame based on the position, velocity, and / or attitude of the target anatomical region and the total system delay. It then controls the inverted U-shaped frame to move longitudinally along the first and second slide rails, ensuring the target anatomical region remains within the permissible imaging field of view at the exposure time. Simultaneously, it determines whether to allow triggering pulse exposure based on the motion phase, the positional deviation between the target position and the imaging isocenter, and the safety enable status. For multiple motion cycles or repeated passes of the same motion task, the controller can acquire complementary subsets of projection angles at the same target motion phase and associate each cone-beam projection frame with the corresponding frame track displacement, projection angle, time information, motion phase, and target pose for subsequent projection consistency screening, motion correction, and 3D or 4D reconstruction.

[0010] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein a first slider and a second slider are respectively provided on the first slide rail and the second slide rail, and the inverted U-shaped frame is connected between the first slide rail and the second slide rail through the first slider and the second slider.

[0011] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein the driving mechanism is connected to the first slider and the second slider, and drives the first slider and the second slider to move the inverted U-shaped frame along the first slide rail and the second slide rail.

[0012] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein the driving mechanism is any one of the following: Linear motor; Servo motors and their compatible synchronous belts; Servo motors and their compatible ball screws.

[0013] In one embodiment, the present invention provides a CBCT system for dynamic human motion imaging, wherein the projection angle modulation mechanism may include a slewing bearing, a rotary motor and an angle encoder, and the X-ray source and the detector are mounted on a rotating assembly and rotate relative to the scanning area within a preset angle range; or, the projection angle modulation mechanism may be a multi-source multi-detector array to achieve multi-angle acquisition without the need for continuous rotation.

[0014] According to the present invention, a CBCT system for dynamic human motion imaging further includes an adjustment platform capable of adjusting height and tilt, the adjustment platform supporting the first slide rail and the second slide rail.

[0015] According to the present invention, a CBCT system for dynamic human motion imaging includes an adjustment platform comprising a base, a first lifting mechanism located at one end of the bottom of the base, and a second lifting mechanism located at the other end of the bottom of the base, wherein the base carries the first slide rail and the second slide rail.

[0016] According to the present invention, a CBCT system for dynamic human motion imaging includes an adjustment platform comprising a platform, a base, and a third lifting mechanism. The platform carries a first slide rail and a second slide rail. The rear end of the platform is connected to the base via a hinge shaft. The lower end of the third lifting mechanism is fixed to the base, and the upper end of the third lifting mechanism is connected to the front end of the platform via a hinge ball.

[0017] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein the lengths of the first slide rail and the second slide rail range from 1.5 to 2 meters.

[0018] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein the tilt range of the adjustment platform is 0-20°.

[0019] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein the sensor is mounted in the middle of the crossbeam of the inverted U-shaped frame.

[0020] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein the sensor is any one of the following or any combination thereof: an infrared beam array, an ultrasonic ranging sensor, a pressure sensing pad, or an inertial measurement unit.

[0021] According to the present invention, a CBCT system for dynamic human motion imaging is provided, wherein the controller is configured to receive position and / or velocity information of the subject from the sensor, send drive commands to the drive mechanism, and send projection data acquisition commands to the X-ray source and the detector; The drive mechanism receives a drive command from the controller and drives the inverted U-shaped frame to move along the first slide rail and the second slide rail to follow the subject. The X-ray source and the detector receive projection data acquisition instructions from the controller to acquire projection data of the subject during movement.

[0022] In one embodiment, the present invention provides a CBCT system for dynamic human motion imaging, wherein the controller is configured to receive position, velocity and / or gait phase information of the subject from the sensor, perform delay compensation and prediction for the follow-up control of the inverted U-shaped frame, send drive commands to the drive mechanism, and send synchronous multi-angle projection data acquisition commands to the X-ray source, the detector and the projection angle modulation mechanism at a preset gait phase. The drive mechanism receives a drive command from the controller and drives the inverted U-shaped frame to move along the first slide rail and the second slide rail to follow the subject, so that the target anatomical area is kept in the center of the imaging field of view; The X-ray source and the detector receive projection data acquisition instructions from the controller to perform pulse exposure and acquire cone-beam projection data at a preset gait phase. The projection angle modulation mechanism receives angle modulation instructions to form multi-angle acquisition. The controller synchronously records the orbital pose and rotation angle for motion correction and three-dimensional / four-dimensional reconstruction.

[0023] The present invention also provides a dynamic human motion imaging method, implemented based on the CBCT system for dynamic human motion imaging described in any of the above claims, comprising: The sensor senses the position and / or velocity of the subject during movement in the CBCT system for dynamic human motion imaging, and sends the subject's position and / or velocity information to the controller. The controller sends drive commands to the drive mechanism and projection data acquisition commands to the X-ray source and detector based on the position and / or velocity information of the subject. The inverted U-shaped frame is driven by the drive mechanism according to the drive command to move along the first and second slide rails to follow the subject. The X-ray source and detector collect projection data of the subject during movement according to the projection data acquisition instructions, which is used for the reconstruction of the subject's three-dimensional motion data.

[0024] The present invention also provides a dynamic human motion imaging method, implemented based on the CBCT system for dynamic human motion imaging described in any of the above claims, comprising: The sensor senses the real-time position, velocity, and / or gait phase of the subject during movement in the CBCT system for dynamic human motion imaging, and sends the information to the controller. The controller generates a follow-up control command for the inverted U-shaped frame based on the information and performs delay compensation prediction. It then sends a drive command to the drive mechanism and simultaneously sends a synchronous multi-angle projection data acquisition command to the X-ray source, detector, and projection angle modulation mechanism at a preset gait phase. The drive mechanism drives the inverted U-shaped frame to move along the first and second slide rails to follow the subject according to the drive command, so that the target anatomical area is kept in the center of the imaging field of view. Pulsed exposure is performed at a preset gait phase using an X-ray source and detector to acquire cone-beam projection data. Simultaneously, multi-angle acquisition is achieved through a projection angle modulation mechanism. The controller synchronously records the orbital pose and rotation angle, and performs geometric calibration, motion correction, and 3D / 4D reconstruction on the projection data.

[0025] The CBCT system and method for dynamic human motion imaging provided by this invention have at least the following technical advantages: By adopting a rigid inverted U-shaped frame structure, the X-ray source and detector are fixed as a rigid whole, so that the geometric relationship between the source and detector remains constant during the follow-up process. This avoids the synchronization error of independent left and right drives and the geometric deviation caused by vibration and micro-motion of flexible connection, thus meeting the geometric accuracy requirements of cone-beam CT reconstruction.

[0026] The dual-rail structure used in the system can provide a scanning stroke of up to 1.5–2 meters, which can cover the key walking range of natural human walking. It supports the uninterrupted acquisition of time-series projection data in scenarios such as continuous walking and weight-bearing movement, providing a more complete data foundation for gait / weight-bearing function assessment.

[0027] It innovatively introduces an adjustable platform with adjustable height and tilt angle, which can set the isocenter height according to the height of the subject and the target anatomical part, and can simulate real environments such as going up and down stairs / ramps, thereby supporting dynamic imaging of various postures such as horizontal walking, going up and down stairs, standing still, squatting and standing up.

[0028] By integrating position / velocity / gait phase sensors and controllers, the system implements delayed-compensated follow-up control of the inverted U-shaped frame to keep the target anatomical area in the center of the imaging field of view; and can trigger pulse exposure at preset gait phases (such as the ground phase / support phase) to reduce blurring and artifacts caused by relative motion from the acquisition timing.

[0029] By setting a projection angle modulation mechanism on the inverted U-shaped frame, multi-angle cone beam projection acquisition is formed during the follow-up process. Combined with the synchronous recording of orbital pose and rotation angle, the projection data can be geometrically calibrated and motion corrected, thereby realizing three-dimensional reconstruction or four-dimensional reconstruction by gait phase binning. At the same time, combined with low-dose strategies such as pulse exposure and iterative / sparse reconstruction, the radiation dose to the subject and operator is significantly reduced while ensuring image quality.

[0030] In summary, this invention, through the collaborative design of a rigid integrated structure, long-stroke slide rail, adjustable platform, delay-compensated servo control, and multi-angle projection acquisition, systematically solves the problems of geometric stability, coverage, and reconstruction consistency under dynamic motion conditions, enabling the acquisition of high-quality, low-dose three-dimensional / four-dimensional dynamic images under real motion conditions. It has broad application prospects in clinical diagnosis, rehabilitation assessment, and biomechanical research. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a front view of a CBCT system for dynamic human motion imaging provided by the present invention.

[0033] Figure 2 This is an application example diagram of a CBCT system for dynamic human motion imaging provided by the present invention.

[0034] Figure 3 This is a schematic diagram of the follow-up control and phase gating acquisition process provided by the present invention.

[0035] Figure 4This is a schematic diagram of projection angle modulation and pose recording provided by the present invention.

[0036] Figure 5 This is a schematic diagram of the projection frame motion correction and 3D / 4D reconstruction process provided by the present invention.

[0037] Figure 6 This is a schematic diagram of the safety interlocking and anti-collision control provided by the present invention.

[0038] Figure 7 This is a schematic diagram of geometric calibration and error compensation provided by the present invention.

[0039] Figure 8 This is a schematic diagram of the low-dose phase-gated exposure timing provided by the present invention.

[0040] Figure 9 This is a schematic diagram illustrating the dynamic imaging verification and effect evaluation provided by the present invention.

[0041] Reference numerals in the attached figures: 1: First slide rail; 2: Second slide rail; 3: Adjustment platform; 4: First slider; 5: Second slider; 6: Inverted U-shaped frame; 7: X-ray source; 8: Detector; 9: Sensor. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] See Figures 1 to 5 The present invention provides a CBCT system for dynamic human motion imaging, which may include: The first slide rail 1 and the second slide rail 2 are set in parallel. An adjustment platform 3 is capable of adjusting its height and tilt, and the adjustment platform 3 supports the first slide rail 1 and the second slide rail 2; A first slider 4 and a second slider 5 are respectively provided on the first slide rail 1 and the second slide rail 2; The inverted U-shaped frame 6, which spans between the first slide rail 1 and the second slide rail 2, is connected by the first slider 4 and the second slider 5. X-ray source 7 and detector 8 are fixed to the opposite positions of the two side walls of the inverted U-shaped frame 6. The central axes of X-ray source 7 and detector 8 intersect at the center of the scanning area to ensure projection coverage of the target. The two are precisely aligned by the inverted U-shaped frame 6, forming a CBCT transmitter-receiver pair. X-ray source 7 and detector 8 are constrained by the same rigid support structure, ensuring that the source-detector distance, the direction of the main beam relative to the detector, and the orientation of the detector relative to the X-ray source of the same source-detector pair remain within the pre-calibrated geometric relationship and allowable error range during the longitudinal movement of the inverted U-shaped frame. The source-detector relative geometric maintenance referred to here is a calibrated relationship and does not limit the projection angle of the source-detector pair relative to the target anatomical area to remain unchanged. The projection angle modulation mechanism (not shown) mounted on the inverted U-shaped frame 6 is used to drive the X-ray source 7 and / or detector 8 to rotate around the rotation axis passing through the scanning area, and the corresponding rotation angle is output by the angle encoder to form a multi-angle cone beam projection acquisition. The drive mechanism is connected to the first slider 4 and the second slider 5, and drives the first slider 4 and the second slider 5 to move the inverted U-shaped frame 6 along the first slide rail 1 and the second slide rail 2. Sensor 9 is used to sense the position and / or speed of the subject in the scanning area. Sensor 9 can be installed in the middle of the crossbeam of the inverted U-shaped frame 6, or at an appropriate position on the first slide rail 1 and the second slide rail 2. The controller is connected in communication with the sensor 9, the drive mechanism, the X-ray source 7, and the detector 8. The controller can estimate the gait phase of the subject based on the output of the sensor 9, and send a drive command to the drive mechanism to drive the inverted U-shaped frame 6 to move synchronously with the subject, and send a projection data acquisition command to the X-ray source 7 and the detector 8 to acquire projection data in sequence.

[0044] In one embodiment, the projection angle modulation mechanism is a multi-source, multi-detector array, including multiple X-ray sources distributed at preset fixed angles along the circumference of the scanning area and detectors corresponding to each X-ray source. The geometric angle of each source-detector relative to the scanning area is constant. This allows for the acquisition of multiple cone-beam projections at the same time or time-division without continuous rotation. The controller records the fixed projection angle of each source-detector relative to the scanning area, along with the orbital displacement and timestamp, for geometric calibration, motion correction, and 3D / 4D reconstruction.

[0045] In one embodiment, the lengths of the first and second slide rails range from 1.5 to 2 meters to cover the complete gait cycle, and are preferably 1.8 meters in this embodiment.

[0046] In one embodiment, the tilt range of the adjustment platform is 0-20°, adapting to different scenarios such as walking on level ground, standing still, and walking on slopes. For example, a tilt of 0° corresponds to walking on level ground, and as the tilt increases, it can approximately simulate walking environments on slopes or steps with different inclines within this range. The specific tilt can be set according to the height of the subject, the target anatomical location, and the motion scenario to be evaluated. When the adjustment platform is at a non-zero tilt angle, the controller can combine the recorded platform tilt angle, along with the track displacement, rotation angle, and timestamp, as inputs for geometric calibration and motion correction, and adjust the follow-up control of the inverted U-shaped frame accordingly to keep the target anatomical region near the preset isocenter height. The platform tilt angle α relative to the reference horizontal plane is recorded, and the platform tilt angle α is used as one of the input parameters for coordinate transformation between the frame coordinate system and the motion channel reference coordinate system, as well as for the geometric determination of the projection geometry of each cone-beam projection frame, so that the changes in the motion channel direction and imaging isocenter position caused by the platform tilt can be incorporated into the geometric correction and motion compensation process.

[0047] In one embodiment, the height and tilt adjustment of the adjustment platform can be achieved by any of the following structures. Firstly, the adjustment platform includes a base, a first lifting mechanism located at one end of the bottom of the base, and a second lifting mechanism located at the other end of the bottom of the base. The base carries the first slide rail and the second slide rail, and the overall lifting and tilting of the base is achieved through the differential lifting of the first lifting mechanism and the second lifting mechanism.

[0048] Secondly, as an alternative implementation of the aforementioned adjustment platform, the adjustment platform includes a platform, a base, and a third lifting mechanism. The platform carries the first and second slide rails. The rear end of the platform is connected to the base via a hinge shaft. The lower end of the third lifting mechanism is fixed to the base, and the upper end of the third lifting mechanism is connected to the front end of the platform via a hinge ball.

[0049] In one embodiment, the inverted U-shaped frame is made of a high-strength, lightweight metal material.

[0050] In one embodiment, the drive mechanism is any one of the following: a linear motor, a servo motor and a synchronous belt adapted thereto, or a servo motor and a ball screw adapted thereto.

[0051] In one embodiment, the sensor is any one or any combination thereof: an infrared beam array, an ultrasonic ranging sensor, a pressure-sensing pad, or an inertial measurement unit. For example, an infrared sensor is placed at the starting end of the slide rail, triggering the start of scanning when the subject passes the starting position; an inertial sensor is installed on the inverted U-shaped frame to measure the position and speed of the frame in real time, achieving closed-loop control. In this embodiment, it is preferable to arrange multiple infrared sensors along the walking direction of the subject on the slide rail path to capture the subject's gait rhythm and calculate the real-time position and walking speed in the controller.

[0052] In one embodiment, the target tracking sensor, frame position or pose detection unit, projection angle encoder, X-ray source and detector generate timestamps using a unified time reference; or, each unit generates timestamps using a local clock, and the controller converts them to the same time reference according to the pre-obtained clock deviation and clock drift relationship, so that the target position or pose, frame track position, projection angle and motion phase associated with the same cone beam projection frame correspond to the same exposure time.

[0053] In one embodiment, the controller includes a high-speed data acquisition module, a motion control module, and a reconstruction processing module. The controller integrates the outputs of sensors such as infrared / IMU / pressure sensors to estimate the real-time position, velocity, and gait phase of the target anatomical region of the subject. Based on system sampling and drive delay, it performs feedforward prediction compensation to adjust the position and velocity of the inverted U-shaped frame on the slide rail in real time, so that the target anatomical region is kept in the center of the imaging field of view.

[0054] In one implementation, the total system delay τ includes at least one of the following: sensor sampling delay, data transmission and control calculation delay, drive response delay, and exposure trigger delay. Let the position and velocity of the target anatomical region along the slide rail direction at the current time t be p(t) and v(t), respectively. The controller can predict the target's longitudinal position at the exposure time based on p(t+τ)=p(t)+v(t)τ; when the target's longitudinal acceleration a(t) is available, it can also be predicted based on p(t+τ)=p(t)+v(t)τ+0.5a(t)τ². The controller generates position and / or velocity control commands for the inverted U-shaped frame based on the deviation between the predicted position and the longitudinal position of the imaging isocenter, and performs closed-loop correction using the frame position detection results. The above prediction relationship is an exemplary implementation; state estimation, Kalman filtering, model predictive control, or other control methods with the same prediction function can also be used. Specifically, when the subject is detected entering a preset gait phase (such as the support phase / landing phase), the controller controls the projection angle modulation mechanism to rotate continuously or in segments within a preset angle range. Simultaneously, it controls the X-ray source to perform low-dose pulsed exposure and drives the detector to synchronously acquire projection frames, recording track displacement, rotation angle, and timestamps. When a swaying phase is detected, the exposure can be paused or reduced, and the inverted U-shaped frame can be moved to the next position. Through this closed-loop control of phase gating and pose recording, cone-beam projection data sufficient for the required angle coverage for reconstruction can be accumulated within one or more gait cycles.

[0055] In one implementation, the controller maintains a set of already acquired valid projection angles and a set of missing projection angles that still need to be acquired for a predetermined target motion phase. Based on the set of missing projection angles, it determines the subset of projection angles corresponding to subsequent motion cycles or re-passes. After each acquisition, the controller determines whether the projection frame is valid based on the motion phase error, target position deviation, target attitude deviation, and geometric consistency evaluation results corresponding to the projection frame. Projection angles corresponding to valid projection frames are added to the set of already acquired valid projection angles, while projection angles corresponding to invalid projection frames are re-added to the set of missing projection angles and allocated to subsequent motion cycles or re-passes for supplementary acquisition, until the set of valid projection angles corresponding to the target motion phase meets the predetermined reconstruction angle coverage conditions.

[0056] During scanning, the controller drives the projection angle modulation mechanism according to a preset angle sequence / angular velocity, causing the X-ray source and detector to rotate relative to the scanning area within a preset angle range, and triggering low-dose pulse exposure at a preset gait phase; the detector synchronously acquires cone-beam projection frames. Each projection frame is associated with and recorded for its orbital displacement, rotation angle, and timestamp, serving as input for geometric calibration, motion correction, and reconstruction. Because the inverted U-shaped frame maintains a constant source-detector geometric relationship, and the acquisition timing is limited by gait phase gating, the projection sequence can be considered as multi-angle acquisition under quasi-static conditions after motion correction, making it suitable for algorithms such as FDK, iterative reconstruction, and sparse view reconstruction.

[0057] Further, see Figure 6 The system of this invention can be equipped with a safety interlock and anti-collision control module. This module may include one or more of the following: a distance sensor, a light curtain, a vision sensor, a torque / current detection unit, a travel limit switch, an emergency stop button, and a high-voltage enable detection unit. The interlock judgment can be performed by an independent safety controller or by the controller itself. The safety interlock and anti-collision control can be implemented by an independent safety controller or by a safety control link within the controller that is independent of the imaging acquisition control logic. A safety enable signal is generated when the safety interlock is active, and its control priority is higher than that of the frame servo and X-ray exposure commands.

[0058] When the system detects that the subject or obstacle has entered the preset safe distance, the inverted U-shaped frame is close to the end of the stroke, the torque or current of the drive mechanism exceeds the threshold, an emergency stop is triggered, or the high voltage condition is abnormal, the safety controller will take precedence over the imaging acquisition command to execute speed limiting, braking, stopping the drive, cutting off X-ray exposure, turning off high voltage enable and / or audible and visual alarms; only after the fault is cleared and the reset self-test is completed can the follow-up and gating exposure be re-enabled.

[0059] Further, see Figure 7This invention allows for geometric calibration and error compensation before and / or during data acquisition. Specifically, a calibration phantom is placed in the scanning area, and by combining the orbital displacement encoder, projection angle encoder, and timestamp, the source-detector distance, detector principal point offset, detector tilt angle, and geometric matrix M_i for each projection frame are determined.

[0060] The controller or reconstruction module can bind the projected frame P_i with the orbital displacement x_i, projection angle θ_i, timestamp t_i, gait phase φ_i, and the geometric matrix M_i for each frame. When the geometric calibration residual Δ_i exceeds a preset threshold, the corresponding projected frame is subject to rejection, resampling, geometric compensation, or recalibration prompts, thereby reducing the accumulation of geometric errors in motion acquisition. For projected frames obtained across different motion cycles or repeated passes, consistency evaluation can also be performed based on motion phase error, target position deviation, target attitude deviation, and geometric consistency residual. Only when the above parameters meet their respective preset conditions is the projected frame added as a valid frame to the projection set of the corresponding motion phase; for projected frames where at least one parameter exceeds the corresponding threshold, they are marked as invalid frames or their reconstruction weight is reduced.

[0061] For the i-th cone-beam projection frame P_i, the controller or reconstruction module associates the projection frame P_i with the frame orbit displacement x_i, projection angle parameter θ_i, timestamp t_i, motion phase φ_i, and the position and / or orientation q_i of the target anatomical region corresponding to the exposure time. Based on the pre-calibrated source-detector geometry, frame orbit displacement x_i, projection angle parameter θ_i, and target orientation q_i, it determines the projection geometry or projection matrix M_i corresponding to the projection frame, thus forming a projection record corresponding to the i-th projection frame. The projection geometry characterizes at least three time-varying factors: the displacement of the inverted U-shaped frame along the slide rail direction, the projection angle of the source-detector pair relative to the target region, and the position and orientation of the target anatomical region itself. Therefore, for cone-beam projection frames obtained from different motion cycles, even if their motion phases are the same, their actual projection geometry can be determined based on their respective projection records, rather than treating all projection frames with the same motion phase as having completely identical target positions and orientations.

[0062] Further, see Figure 8 Low-dose phase-gated exposure can be achieved using a timing control method: the controller generates a gating window based on the target gait phase φ(t), the center position of the target anatomical region, the predicted longitudinal position of the target, and the predicted position of the inverted U-shaped frame. The X-ray source short pulse exposure is triggered only when the gait phase is preset and the deviation between the target anatomical region and the center of the imaging field of view is less than a preset position threshold. The controller also controls the detector to synchronously acquire cone-beam projection frames and perform integration within the corresponding exposure window. Exposure is prohibited or delayed when the swing phase, position deviation exceeds the limit, or safety interlock is triggered.

[0063] Further, see Figure 9 This invention can be dynamically verified using a motion phantom or gait simulation platform. During verification, repeatable target translation and attitude trajectories can be set and reference trajectories recorded. The servo-tracking, gated, frame-by-frame pose recording, and projection consistency screening modes of this invention are compared with non-servo-tracking or non-gated control modes. Evaluation indicators may include one or more of the following: target center offset, target longitudinal tracking error, target attitude error, geometric calibration residual, motion artifact degree, fixed marker reprojection residual, effective projection angle coverage, number of missing angle re-sampling attempts, reconstruction motion artifact degree, number of repeated scans, and dose-related indicators, to respectively evaluate servo-tracking performance, frame-by-frame geometric consistency, projection acquisition integrity, and reconstruction quality. This verification method is used to demonstrate that the technical effects produced by this invention can be evaluated by objective data.

[0064] Based on the aforementioned CBCT system for dynamic human motion imaging, a dynamic human motion imaging method can be developed, including: Before entering the dynamic projection acquisition state, initialization and self-tests can be performed, including: completing source-detector geometric calibration; establishing the correspondence between the motion channel coordinate system, the inverted U-shaped frame coordinate system, and the target tracking coordinate system; verifying the zero point, direction, and time synchronization status of the track position detection unit, projection angle detection unit, and target tracking sensor; reading or determining system delay parameters; and performing checks on low-speed operation, travel limit, emergency stop, high-voltage enable, and safety interlocks of the drive mechanism. The controller is allowed to enter the dynamic projection acquisition state only when the necessary geometric calibration, coordinate correspondence, time synchronization, and safety status meet the preset conditions.

[0065] Set the height and / or tilt of the adjustment platform; The subject is instructed to walk or go up and down steps on the adjustment platform, that is, between the first slide rail and the second slide rail; The sensor detects the position and / or velocity of the subject and sends the position and / or velocity information of the subject to the controller. The controller sends drive commands to the drive mechanism and projection data acquisition commands to the X-ray source and detector based on the position and / or velocity information of the subject. The inverted U-shaped frame is driven by the drive mechanism according to the drive command to move along the first and second slide rails to follow the subject. The X-ray source and detector collect projection data of the subject during movement according to the projection data acquisition command. Specifically, the X-ray source performs pulse exposure when the subject reaches the preset phase, and the detector collects the projection sequence to obtain projection data. The preset phase includes the grounding phase and the support phase of the gait. Based on the projection data of the subject during movement, motion correction and three-dimensional reconstruction are performed to obtain a volumetric image of the subject in a dynamic state. Motion correction can be based on the output of the sensor.

[0066] Based on the aforementioned CBCT system for dynamic human motion imaging, a dynamic human motion imaging method can be developed, including: Set the height and / or tilt of the platform to position the target anatomical area at a preset isocentric height, and optionally simulate a ramp / step environment; The test subject was instructed to walk naturally, walk with a load, or go up and down stairs on the adjustment platform (i.e., the walking area between the first and second slide rails); The sensor detects the real-time position, speed, and / or gait phase of the subject and sends the information to the controller. The controller generates a follow-up control command for the inverted U-shaped frame based on the information and performs delay compensation prediction, driving the inverted U-shaped frame to move along the first and second slide rails to follow the subject, so that the target anatomical area is kept in the center of the imaging field of view. When the subject is in a preset gait phase, the controller triggers the X-ray source pulse exposure and controls the detector to synchronously acquire cone-beam projection frames. At the same time, the controller controls the projection angle modulation mechanism to drive the X-ray source and / or detector to rotate around the scanning area according to a preset angle sequence / angular velocity to form multi-angle acquisition, and records the orbital displacement, rotation angle and timestamp. For multiple motion cycles or multiple repetitions of the same motion task, the controller prioritizes allocating projection angles for the current motion cycle from the missing projection angle set. For projection frames that meet the validity conditions, the corresponding projection angles are moved into the valid projection angle set. For invalid projection frames, the corresponding projection angles are retained or added back to the missing projection angle set for subsequent cycles to be acquired.

[0067] Based on the recorded information, the projected frame is geometrically calibrated and motion corrected, and three-dimensional reconstruction or four-dimensional reconstruction by binning according to gait phase is performed to obtain the volumetric image of the subject in a dynamic state.

[0068] The CBCT system for dynamic human motion imaging provided by this invention can be widely applied in biomechanics and clinical fields. For example, in rehabilitation training, subjects can walk naturally or perform weight-bearing exercises between tracks, and the system captures the motion trajectory and three-dimensional posture of the lower limb joints in real time, helping to assess rehabilitation progress and adjust training programs. In orthopedic diagnosis and treatment, doctors can have subjects walk under controlled weight-bearing conditions, and use the system to observe changes in knee joint space or instability under dynamic weight-bearing, thus aiding in the diagnosis of ligament injuries and other problems. Furthermore, in sports medicine research, this system can be used to analyze athletes' gait, biomechanical parameters, and the impact of training on joint load, providing a scientific basis for improving exercise posture.

[0069] The CBCT system and method for dynamic human motion imaging provided by this invention have at least the following beneficial effects: The rigid inverted U-shaped frame is molded as one piece to fix the X-ray source and detector into a rigid whole, so that the geometric relationship between the source and detector remains constant during the follow-up process. This avoids the synchronization error of independent left and right drives and reduces the geometric deviation caused by vibration and micro-motion of flexible connection, thereby meeting the geometric accuracy requirements of cone-beam CT reconstruction and ensuring the image clarity during dynamic scanning.

[0070] The dual sliding rails in this system are long enough to cover a walking path of approximately 1.5-2 meters, enabling the device to collect continuous projection data throughout the subject's complete gait cycle. In contrast, robotic arm systems often have limited travel and cannot acquire full gait information in a single scan. This system is suitable for full-range 3D imaging in scenarios such as walking and weight-bearing walking.

[0071] With its vertical and tilt adjustment platform, the sliding rail can be raised and lowered to accommodate different heights and standing postures, and can also be tilted simultaneously to simulate the sloping environment of going up and down stairs. Therefore, this system is not only suitable for horizontal walking, but also for dynamic imaging in various postures such as standing still, going up and down stairs, and squatting, achieving a multi-purpose effect.

[0072] The sensors and controller work together to achieve precise synchronization between the movement of the inverted U-shaped frame and the gait of the subject. As the subject walks between the rails, the sensors monitor their movement rhythm in real time, and the controller drives the inverted U-shaped frame to translate at a matching speed, ensuring that the scanning process is synchronized with the gait. This ensures that each projection frame captures the same viewpoint of the target area during dynamic movement, reducing motion artifacts and improving the accuracy of 3D reconstruction.

[0073] This system supports acquiring the required images while the subject is in motion, thereby reducing the number of repeated scans. Simultaneously, by combining low-dose strategies such as pulsed exposure and iterative / sparse view reconstruction, it can reduce the radiation dose to the subject while ensuring image quality. This is of great significance for subjects who require multiple assessments of the effectiveness of rehabilitation training.

[0074] By incorporating distance detection, light curtain / visual detection, torque detection, travel limit, emergency stop, and high voltage enable status into the same interlocking logic through the safety interlocking and anti-collision control module, both the inverted U-shaped frame follow-up and X-ray exposure are subject to safety constraints. When safety conditions are not met, the system can prioritize speed limiting, braking, cutting off exposure, or turning off high voltage enable, thereby improving the engineering feasibility and safety of use during dynamic human motion scanning.

[0075] By combining geometric calibration, error compensation, low-dose timing control, and dynamic imaging verification indicators, each frame of projection data is bound to pose, time, gait phase, and geometric matrix, and frames with excessive residuals can be corrected or eliminated. This further reduces motion artifacts and geometric inconsistencies, and provides verifiable evaluation criteria for the technical effect of this invention compared to non-follow-up or non-gated imaging methods.

[0076] In summary, this invention, through an innovative sliding rail + inverted U-shaped frame structure and synchronous control, maintains the calibrated geometric relationship between the source and detector under the condition that the target anatomical region and the imaging frame move simultaneously. This is achieved through an integral rigid inverted U-shaped frame and a common rigid support structure. The target position at the exposure time is predicted based on the target motion state and system delay, and projection acquisition is jointly controlled by motion phase, target position deviation, and safety enable conditions. Simultaneously, the frame track displacement, projection angle, target attitude, motion phase, and time information are correlated to each cone-beam projection frame, forming a frame-by-frame determinable composite projection geometry. Valid projections are selected based on phase, position, attitude, and geometric consistency across motion cycles. For projection frames deemed invalid, their corresponding missing projection angles can be redistributed to subsequent motion cycles or repeated for supplementary acquisition, gradually forming a consistent projection set that meets the reconstruction angle coverage conditions for the same target motion phase. This provides a data foundation for three-dimensional or four-dimensional cone-beam volume reconstruction under natural human motion conditions. This invention effectively achieves highly stable, high-resolution CBCT imaging under dynamic human motion (walking, weight-bearing, etc.), expanding the application scope of CBCT and possessing significant clinical and research value.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A CBCT system for dynamic human motion imaging, characterized in that, The device includes a first and second slide rail arranged in parallel, an inverted U-shaped frame, an X-ray source, a detector, a drive mechanism, a sensor, and a controller. The inverted U-shaped frame spans between the first and second slide rails, and the X-ray source and the detector are fixed at their relative positions on opposite sides of the inverted U-shaped frame. The sensor is used to sense the position, velocity, and / or gait phase of the subject. The controller is communicatively connected to the sensor, the drive mechanism, the X-ray source, and the detector, and is configured to control the drive mechanism to drive the inverted U-shaped frame to move along the first and second slide rails to follow the subject, based on the output of the sensor, and to control the X-ray source and the detector to collect cone-beam projection data during the subject's movement.

2. The CBCT system for dynamic human motion imaging according to claim 1, characterized in that, The first slide rail and the second slide rail are respectively provided with a first slider and a second slider. The inverted U-shaped frame is connected between the first slide rail and the second slide rail through the first slider and the second slider. The driving mechanism is connected to the first slider and / or the second slider, and drives the first slider and the second slider to make the inverted U-shaped frame slide along the first slide rail and the second slide rail.

3. The CBCT system for dynamic human motion imaging according to claim 1 or 2, characterized in that, The inverted U-shaped frame is a rigid frame formed in one piece. The X-ray source and the detector are fixed as a rigid whole by the inverted U-shaped frame, so that the relative geometric relationship between the X-ray source and the detector remains constant as the inverted U-shaped frame moves along the first slide rail and the second slide rail.

4. The CBCT system for dynamic human motion imaging according to any one of claims 1-3, characterized in that, It also includes an adjustment platform capable of adjusting height and tilt, the adjustment platform supporting the first slide rail and the second slide rail; the adjustment platform includes a platform, a base and a lifting mechanism, the rear end of the platform is connected to the base via a hinge shaft, the lower end of the lifting mechanism is fixed to the base, the upper end of the lifting mechanism is connected to the front end of the platform, and / or the adjustment platform includes a base and a first lifting mechanism and a second lifting mechanism respectively disposed at both ends of the bottom of the base; the tilt range of the adjustment platform is 0-20°.

5. The CBCT system for dynamic human motion imaging according to any one of claims 1-4, characterized in that, The sensor includes one or more of the following: an infrared beam array, an ultrasonic ranging sensor, a pressure sensing pad, an inertial measurement unit, and a vision sensor; the inertial measurement unit is disposed on the inverted U-shaped frame and / or the part worn by the subject, and is used to measure the position, velocity, posture, or gait phase of the inverted U-shaped frame and / or the subject.

6. The CBCT system for dynamic human motion imaging according to any one of claims 1-5, characterized in that, The controller is configured to perform delay compensation and feedforward prediction compensation on the follow-up control of the inverted U-shaped frame based on the system's sampling delay and drive delay, and according to the subject's position, velocity, and / or gait phase output by the sensor, to adjust the position and / or velocity of the inverted U-shaped frame along the first and second slide rails in real time, so that the target anatomical area of ​​the subject is kept in the center of the imaging field of view; the controller is also configured to perform closed-loop correction on the actual movement of the inverted U-shaped frame based on the position and / or velocity feedback of the inverted U-shaped frame.

7. The CBCT system for dynamic human motion imaging according to any one of claims 1-6, characterized in that, The controller is configured to determine the gate window based on the gait phase of the subject, the center position of the target anatomical region, and the predicted position of the inverted U-shaped frame; when the subject is in a preset gait phase and the deviation between the center position of the target anatomical region and the predicted position of the inverted U-shaped frame is less than a preset position threshold, the X-ray source is triggered to perform pulse exposure and the detector is controlled to synchronously acquire cone-beam projection frames. When the subject is in the oscillating phase, the deviation exceeds the preset position threshold, or the exposure safety conditions are not met, the exposure of the X-ray source is prohibited, delayed, or reduced.

8. The CBCT system for dynamic human motion imaging according to any one of claims 1-7, characterized in that, It also includes a projection angle modulation mechanism disposed on the inverted U-shaped frame. The projection angle modulation mechanism is used to drive the X-ray source and / or the detector to rotate relative to the scanning area between the X-ray source and the detector within a preset angle range to form a multi-angle cone-beam projection acquisition. The projection angle modulation mechanism includes a slewing bearing, a rotary motor and an angle encoder, or a multi-source multi-detector array. The controller is also communicatively connected to the projection angle modulation mechanism and records the rotation angle output by the projection angle modulation mechanism.

9. The CBCT system for dynamic human motion imaging according to claim 8, characterized in that, The controller is also configured to simultaneously record the orbital displacement of the inverted U-shaped frame, the rotation angle output by the projection angle modulation mechanism, the corresponding timestamp, and / or gait phase when acquiring each frame of cone beam projection; the system also includes a geometric calibration module, which is configured to determine the source-detector distance, detector principal point offset, detector tilt angle, and / or geometric matrix of each frame corresponding to each projection frame based on the calibration phantom image, the orbital displacement, the rotation angle, and the timestamp.

10. The CBCT system for dynamic human motion imaging according to claim 9, characterized in that, The controller is configured to, when the geometric calibration residual exceeds a preset threshold, discard, resample, geometrically compensate, or recalibrate the corresponding projection frame, and use the corrected projection frame for three-dimensional reconstruction or four-dimensional reconstruction by gait phase binning.

11. The CBCT system for dynamic human motion imaging according to any one of claims 7-10, characterized in that, The controller is further configured to, during multiple gait cycles of the subject traversing the walking area between the first and second slide rails, trigger pulse exposures at different projection angles at preset gait phases of each gait cycle to acquire cone-beam projection frames, and, based on the recorded rotation angles and track displacements, merge the multi-angle cone-beam projection frames acquired in the multiple gait cycles into a projection set that satisfies the angle coverage range of three-dimensional or four-dimensional reconstruction.

12. The CBCT system for dynamic human motion imaging according to any one of claims 1-11, characterized in that, It also includes a safety interlock module, which comprises at least one of a distance detection unit, a light curtain detection unit, a visual detection unit, a torque detection unit, a travel limit unit, an emergency stop unit, and a high-voltage enable detection unit; the controller or independent safety controller is configured to perform deceleration, braking, stopping the drive mechanism, prohibiting X-ray source exposure, and / or turning off the high-voltage enable when the safety interlock module detects that the person being tested or an obstacle has entered a preset safe distance, the torque of the drive mechanism exceeds the limit, the travel exceeds the limit, an emergency stop is triggered, or the high-voltage state is abnormal.

13. A dynamic human motion imaging method, characterized in that, The CBCT system for dynamic human motion imaging according to any one of claims 1-12 includes: setting the height and / or tilt of the adjustment platform; moving the subject between the first slide rail and the second slide rail; sensing the subject's position, speed, and / or gait phase using sensors; controlling a drive mechanism to drive an inverted U-shaped frame to follow the subject's movement along the first slide rail and the second slide rail according to the output of the sensors using a controller; acquiring cone-beam projection data during the subject's movement using an X-ray source and a detector; and performing three-dimensional or four-dimensional reconstruction based on the cone-beam projection data.

14. The dynamic human motion imaging method according to claim 13, characterized in that, The controller generates follow-up control commands for the inverted U-shaped frame based on the subject's position, velocity, and / or gait phase information, and performs delay compensation prediction based on the system's sampling delay and drive delay, so that the inverted U-shaped frame follows the subject's movement and keeps the subject's target anatomical area in the center of the imaging field of view.

15. The dynamic human motion imaging method according to claim 13 or 14, characterized in that, The gating window is determined based on the gait phase of the subject, the center position of the target anatomical region, and the predicted position of the inverted U-shaped frame; when the subject is in the grounding phase or the support phase and the deviation between the center position of the target anatomical region and the predicted position of the inverted U-shaped frame is less than a preset position threshold, the X-ray source is triggered to perform pulse exposure and the detector is controlled to synchronously acquire cone-beam projection frames. Exposure is prohibited, delayed, or reduced when the wobbling phase or the deviation exceeds a preset position threshold.

16. The dynamic human motion imaging method according to any one of claims 13-15, characterized in that, When acquiring the cone-beam projection data, the X-ray source and / or the detector are driven to rotate relative to the scanning area by the projection angle modulation mechanism according to a preset angle sequence or preset angular velocity to form multi-angle cone-beam projection acquisition, and the orbital displacement, rotation angle, timestamp and / or gait phase of the inverted U-shaped frame are recorded simultaneously.

17. The dynamic human motion imaging method according to claim 16, characterized in that, Based on the recorded orbital displacement, rotation angle, timestamp, and / or gait phase, the acquired projection frames are geometrically calibrated and motion corrected; when the geometric calibration residual exceeds a preset threshold, the corresponding projection frames are discarded, resampled, geometrically compensated, or recalibrated; and the motion-corrected projection data are reconstructed in three dimensions, or binned according to gait phase and reconstructed in four dimensions to obtain the volumetric image of the subject in dynamic state.

18. The dynamic human motion imaging method according to claim 16 or 17, characterized in that, During multiple gait cycles of the subject traversing the walking area between the first and second slide rails, cone-beam projection frames with different projection angle ranges are collected at the same gait phase of each gait cycle. Based on the recorded rotation angle and track displacement, the cone-beam projection frames collected across gait cycles are merged into a projection set that satisfies the reconstruction angle coverage range. Based on this, three-dimensional reconstruction or four-dimensional reconstruction by binning according to gait phase is performed.

Images