Free sampling trajectory positioning method and positioning system for ct imaging

Abstract

The embodiment of the application discloses a free sampling trajectory positioning method and positioning system for CT imaging, and the method comprises the following steps: determining the center position of the region of interest of the collected target; after any one of the X-ray source and the detector moves to any one sampling point along the free sampling trajectory, the other device moves and positions to the corresponding sampling point along the free sampling trajectory according to the center position of the region of interest of the collected target.

Description

Technical Field

[0001] This invention relates to the field of CT imaging technology, and in particular to a free sampling trajectory localization method and localization system for CT imaging. Background Technology

[0002] X-ray computed tomography (CT) produces clear, high-quality tomographic images, playing a vital role in industrial flaw detection, clinical diagnosis, and surgical navigation. Industrial CT allows observation of an object's internal structure without damage, while medical CT helps radiologists identify and diagnose infectious diseases, musculoskeletal disorders, cardiovascular diseases, trauma, and even certain types of cancer. However, in some practical applications, such as scanning immobile objects, performing internal tomographic imaging in the field, or treating immobile patients with special injuries, conventional or mobile CT scanners are inadequate.

[0003] Typically, CT imaging requires the detector and X-ray source to rotate 360 ​​degrees around the target to collect data. Then, the image is reconstructed using either the Filter-Backprojection (FBP) algorithm or the ART iterative algorithm. The FBP reconstruction algorithm is based on traditional signal processing theory and requires complete data, i.e., enough data to be collected within one revolution to reconstruct the image. The iterative algorithm can tolerate some missing data and continuously optimizes the target image through the iterative process, eventually obtaining an image that meets certain requirements. The disadvantage is that it is computationally time-consuming.

[0004] In some practical applications of CT, such as the inspection of important corner components in industry, large-sized important components that are not easy to cut, mammography in medicine, large-pitch spiral CT, and CT imaging of patients who are not easy to move in the field, the data acquisition process is usually limited by the size of the object being acquired and the flexibility of scanning, which makes it impossible to acquire complete data by traditional circular or spiral trajectories, thus making CT reconstruction impossible. Summary of the Invention

[0005] Based on this, it is necessary to propose a free sampling trajectory localization method and localization system for CT imaging to address the above problems.

[0006] A free sampling trajectory localization method for CT imaging, applied in a CT device, the CT device including an X-ray source and a detector, the method comprising:

[0007] Determine the center location of the region of interest of the object being collected;

[0008] After either the X-ray source or the detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory and positions itself to the corresponding sampling point based on the center position of the region of interest of the object being sampled.

[0009] In the above scheme, after any one of the X-ray source and detector moves to any sampling point along the free sampling trajectory, the other device moves along the free sampling trajectory and positions itself to the corresponding sampling point according to the center position of the region of interest of the object being sampled. After that, the method further includes: acquiring the spatial position information, angular velocity information and rotation angle information of the X-ray source and detector respectively, for CT imaging after free sampling trajectory positioning.

[0010] In the above scheme, determining the center position of the region of interest of the target object specifically includes: determining a reference perpendicular line between the X-ray source and the detector, wherein the reference perpendicular line passes through the region of interest of the target object; and determining the center position of the region of interest of the target object based on the reference perpendicular line.

[0011] In the above scheme, determining the reference perpendicular line between the X-ray source and the detector specifically includes: when the central ray emitted by the X-ray source at any position is perpendicular to the acquisition surface of the detector, the central ray is the reference perpendicular line.

[0012] In the above scheme, determining the center position of the region of interest of the collected object based on the reference vertical line specifically includes: the midpoint of the portion of the reference vertical line that passes through the region of interest of the collected object is the center position of the region of interest of the collected object.

[0013] In the above scheme, the other device moves along the free sampling trajectory and positions itself to the corresponding sampling point according to the center position of the region of interest of the object being collected. Specifically, the opposite side of the real-time vertical line between the X-ray source and the detector is the corresponding sampling point; the real-time vertical line passes through the center position of the region of interest of the object being collected.

[0014] In the above scheme, the deviation range of the real-time vertical line is ±5°.

[0015] In the above scheme, the method further includes: before the other device moves along the free sampling trajectory according to the center position of the region of interest of the sampled object and is positioned to the corresponding sampling point, the other device continuously alarms with sound and light during the movement along the free sampling trajectory, and the alarm is deactivated when it moves to the opposite side of the real-time vertical line between the X-ray source and the detector.

[0016] A positioning system for CT imaging using the free sampling trajectory positioning method described in any of the above solutions, the positioning system comprising: a positioning unit and a data acquisition unit;

[0017] The positioning unit is used to determine the position information of the X-ray source and the detector respectively based on the spatial position information, and to determine the center position of the region of interest of the object being collected; it is also used to determine that after any one of the X-ray source and the detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory according to the center position of the region of interest of the object being collected and is positioned to the corresponding sampling point.

[0018] The acquisition unit is used to acquire the spatial position information of the X-ray source and detector corresponding to the positioning unit and transmit it back to the positioning unit.

[0019] In the above scheme, the positioning system includes an audible and visual alarm unit, which is used to continuously sound and light alarms during the movement of another device along the free sampling trajectory before the other device moves along the free sampling trajectory according to the center position of the region of interest of the sampled object and positions itself to the corresponding sampling point. The audible and visual alarm is deactivated when the device moves to the opposite side of the real-time vertical line between the X-ray source and the detector.

[0020] In the above scheme, the positioning unit is specifically used to determine the reference vertical line between the X-ray source and the detector, and the reference vertical line passes through the region of interest of the object being collected; and to determine the center position of the region of interest of the object being collected based on the reference vertical line.

[0021] In the above scheme, the positioning unit is specifically used to take the opposite side of the real-time vertical line between the X-ray source and the detector as the corresponding sampling point; the real-time vertical line passes through the center position of the region of interest of the sampled object.

[0022] A positioning system for CT imaging using the free sampling trajectory positioning method described in any of the above solutions, the system comprising a positioning unit and a data acquisition unit;

[0023] Two positioning units are provided, one on the X-ray source and the other on the detector;

[0024] The acquisition units are set up in pairs and located at any position around the X-ray source and detector, respectively.

[0025] In the above scheme, the positioning unit includes a first main body and a first three-dimensional visual infrared marker. The first main body is disposed on an X-ray source or detector, and the first three-dimensional visual infrared marker is disposed on the top of the first main body along the X, Y, and Z axes, respectively.

[0026] In the above scheme, the acquisition unit includes a second main body, a second three-dimensional visual infrared marker, and a binocular vision module. The second main body is set at any position around the X-ray source and detector. The second three-dimensional visual infrared marker is set on the top of the second main body along the X, Y, and Z axes, respectively. Two binocular vision modules are set and are located on both sides of the second main body.

[0027] In the above scheme, the positioning unit further includes a first gyroscope and a first angle sensor disposed on the first main body; the acquisition unit further includes a second gyroscope and a second angle sensor disposed on the second main body.

[0028] In the above scheme, the system also includes a workstation, which is wirelessly connected to the positioning unit and the acquisition unit respectively, and is used to record the position coordinates and angle information of all sampling points of the X-ray source and detector on the free sampling trajectory.

[0029] The embodiments of the present invention have the following beneficial effects:

[0030] In this invention, after either the X-ray source or the detector moves along a free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory according to the center position of the region of interest of the object being sampled and positions itself to the corresponding sampling point, thereby realizing sampling of arbitrary closed trajectories, 180-degree + sector angle semi-closed trajectories, and finite angle trajectories of a certain angle. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] in:

[0033] Figure 1 This is a flowchart of a free sampling trajectory localization method for CT imaging in one embodiment;

[0034] Figure 2 This is a schematic diagram of the center position of a free sampling trajectory localization method for CT imaging in one embodiment;

[0035] Figure 3 This is a spatial random curve diagram of a free sampling trajectory localization method for CT imaging in one embodiment;

[0036] Figure 4This is a schematic diagram of the reconstruction result of a free sampling trajectory localization method for CT imaging in one embodiment;

[0037] Figure 5 This is a structural block diagram of a positioning system for a free sampling trajectory positioning method for CT imaging in one embodiment;

[0038] Figure 6 This is a schematic diagram of the structure of a positioning unit in a positioning system for a free sampling trajectory positioning method for CT imaging, as shown in one embodiment.

[0039] Figure 7 This is a schematic diagram of the acquisition unit in the positioning system of a free sampling trajectory positioning method for CT imaging in one embodiment.

[0040] Figure 8 This is a schematic diagram of the positioning system of a free sampling trajectory positioning method for CT imaging in one embodiment. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] like Figure 1 As shown, in one embodiment, a free sampling trajectory localization method for CT imaging is provided, applied in a CT device, the CT device including an X-ray source and a detector, the free sampling trajectory localization method specifically includes the following steps:

[0043] Step 101: Determine the center location of the region of interest of the target object;

[0044] Specifically, such as Figure 2 As shown, a reference perpendicular line is determined between the X-ray source and the detector, and the reference perpendicular line passes through the region of interest of the object being collected; the center position P of the region of interest of the object being collected is determined based on the reference perpendicular line.

[0045] When the central ray emitted by the X-ray source at any position is perpendicular to the acquisition surface of the detector, the central ray is the reference perpendicular line.

[0046] The midpoint of the portion of the reference vertical line that passes through the region of interest of the object being collected is the center position P of the region of interest of the object being collected.

[0047] In other words, when the X-ray source and detector are placed at any sampling point, the central ray emitted by the X-ray source is perpendicular to the sampling surface of the detector. The midpoint of the part of the central ray that penetrates the region of interest of the sampled object is the center position P of the region of interest of the sampled object.

[0048] In some embodiments, at any two sampling points, the center position P' of the region of interest of the two collected objects is determined respectively. Then, the midpoint of the line connecting the center positions P' of the two collected objects's regions of interest is determined as the center position P of the region of interest of the collected object.

[0049] In some embodiments, at several sampling points, the center position P' of the region of interest for a corresponding number of collected objects is determined. Then, the center positions P' of the regions of interest of several collected objects are connected, and their geometric center is determined as the center position P of the region of interest of the collected objects.

[0050] Step 102: After any one of the X-ray source and detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory according to the center position of the region of interest of the object being sampled and positions itself to the corresponding sampling point.

[0051] Specifically, the sampling point is located on the opposite side of the real-time vertical line between the X-ray source and the detector; this real-time vertical line passes through the center of the region of interest of the sampled object.

[0052] It should be noted that the X-ray source and detector can move along a free sampling trajectory, or they can move along a 180-degree + fan-angle semi-closed trajectory or a finite angle trajectory of a certain angle, as is used in the prior art.

[0053] For example, assuming that after the detector moves along the free sampling trajectory to any sampling point, the X-ray source moves along the free sampling trajectory until the sampling point is located at the center of the region of interest of the sampled object, where the real-time perpendicular line between the X-ray source and the detector passes through the sampling point. Then, this sampling point is the sampling point where the X-ray source needs to be located.

[0054] Conversely, if the X-ray source is moved first and then the detector is moved, the same process is used.

[0055] Furthermore, before the other device moves along the free sampling trajectory to the center position of the region of interest of the sampled object and is positioned at the corresponding sampling point, it continuously emits an audible and visual alarm during the movement along the free sampling trajectory. When it moves to the opposite side of the real-time vertical line between the X-ray source and the detector, the audible and visual alarm is deactivated.

[0056] For example, assuming the detector moves to any sampling point along the free sampling trajectory, the X-ray source continuously emits an audible and visual alarm during the process of moving to the corresponding sampling point along the free sampling trajectory, that is, informing the user that "the X-ray source has not yet moved to the corresponding sampling point". After moving to the corresponding sampling point, the audible and visual alarm is deactivated, that is, informing the user that "the X-ray source has moved to the corresponding sampling point and data can be collected".

[0057] Conversely, if the X-ray source is moved first and then the detector is moved, the same process is used.

[0058] In other words, the two ends of the real-time vertical line between the X-ray source and the detector are the two corresponding sampling points.

[0059] The deviation range of the real-time vertical line is ±5°.

[0060] After step 102, the method further includes: acquiring the spatial position information, angular velocity information and rotation angle information of the X-ray source and the detector respectively, for CT imaging after free sampling trajectory positioning.

[0061] Specifically, after the X-ray source and detector collect data at the corresponding sampling points, the collected data are reconstructed based on the spatial position information, angular velocity information and rotation angle information of the X-ray source and detector to obtain CT imaging of the free sampling trajectory.

[0062] This invention does not require strict requirements on the acquisition path during the free sampling trajectory movement of the X-ray source and detector; it only needs to meet basic closure requirements (360-degree closed trajectory, 180-degree + fan-angle semi-closed trajectory, and finite angle trajectory sampling at a certain angle).

[0063] This invention has undergone preliminary simulation experiments, such as Figure 3 As shown, a spatial random curve was simulated, which revolves around a digital phantom. The digital phantom was sampled along the trajectory of this curve; 200 sampling points were used in the simulation experiment. Figure 4 As shown, the image reconstructed using spatial random curves as data collected by free sampling trajectories demonstrates the effectiveness of using the free sampling trajectory positioning data collected by the present invention for tomographic imaging.

[0064] like Figure 5 As shown, in one embodiment, a positioning system for a free sampling trajectory positioning method for CT imaging is provided, the positioning system comprising: a positioning unit and a data acquisition unit;

[0065] The positioning unit is used to determine the position information of the X-ray source and the detector respectively based on the spatial position information, and to determine the center position of the region of interest of the object being collected; it is also used to determine that after any one of the X-ray source and the detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory according to the center position of the region of interest of the object being collected and is positioned to the corresponding sampling point.

[0066] The acquisition unit is used to obtain the spatial position information of the X-ray source and detector corresponding to the positioning unit and transmit it back to the positioning unit.

[0067] Furthermore, the positioning system includes an audible and visual alarm unit, which is used to continuously sound and light alarms during the movement of another device along the free sampling trajectory before the other device moves along the free sampling trajectory according to the center position of the region of interest of the sampled object and positions itself to the corresponding sampling point. The audible and visual alarm is deactivated when the device moves to the opposite side of the real-time vertical line between the X-ray source and the detector.

[0068] The positioning unit is specifically used to determine the reference vertical line between the X-ray source and the detector, and the reference vertical line passes through the region of interest of the object being collected; the center position of the region of interest of the object being collected is determined according to the reference vertical line.

[0069] The positioning unit is specifically used to take the opposite side of the real-time vertical line between the X-ray source and the detector as the corresponding sampling point; the real-time vertical line passes through the center of the region of interest of the sampled object.

[0070] like Figure 6 , 7 As shown, in one embodiment, a positioning system for a free sampling trajectory positioning method for CT imaging is provided, characterized in that the system includes a positioning unit and a data acquisition unit;

[0071] Two positioning units are provided, one on the X-ray source and the other on the detector;

[0072] The acquisition units are set up in pairs and located at any position around the X-ray source and detector, respectively.

[0073] The positioning unit includes a first main body 101 and a first three-dimensional visual infrared marker 102. The first main body 101 is disposed on an X-ray source or detector, and the first three-dimensional visual infrared marker 102 is disposed on the top of the first main body 101 along the X, Y, and Z axes, respectively.

[0074] The positioning unit also includes a first gyroscope 103 and a first angle sensor 104 disposed on the first main body 101.

[0075] The acquisition unit includes a second main body 201, a second three-dimensional visual infrared marker 202, and a binocular vision module 203. The second main body 201 is set at any position around the X-ray source and detector. The second three-dimensional visual infrared marker 202 is set on the top of the second main body 201 along the X, Y, and Z axes, respectively. Two binocular vision modules 203 are provided and are located on both sides of the second main body 201.

[0076] The binocular vision module 203 can also be a laser 3D spatial positioning module, which acquires spatial position information by means of laser.

[0077] The acquisition unit also includes a second gyroscope 204 and a second angle sensor 205 mounted on the second main body 201.

[0078] Each binocular vision module 203 is equipped with two sets of infrared cameras.

[0079] The system also includes a workstation, which is wirelessly connected to the positioning unit and the acquisition unit to record the position coordinates and angle information of all sampling points of the X-ray source and detector on the free sampling trajectory.

[0080] For example, such as Figure 8 As shown, the system includes a positioning unit, a data acquisition unit, and a workstation. Two positioning units are provided and located on the X-ray source and the detector, respectively. Two data acquisition units are provided and located at any position around the X-ray source and the detector, respectively. The workstation is wirelessly connected to the positioning unit and the data acquisition unit, respectively, and is used to record the position coordinates and angle information of all sampling points of the X-ray source and the detector on the free sampling trajectory.

[0081] When any one of the X-ray source and detector moves along the free sampling trajectory, at least one of the positioning unit, acquisition unit, and workstation should be stationary as a reference point to assist other devices in obtaining spatial position information.

[0082] In one embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, causes the processor to perform the following steps:

[0083] Step 101: Determine the center location of the region of interest of the target object;

[0084] Specifically, a reference vertical line is determined between the X-ray source and the detector, and the reference vertical line passes through the region of interest of the object being collected; the center position P of the region of interest of the object being collected is determined based on the reference vertical line.

[0085] When the central ray emitted by the X-ray source at any position is perpendicular to the acquisition surface of the detector, the central ray is the reference perpendicular line.

[0086] The midpoint of the portion of the reference vertical line that passes through the region of interest of the object being collected is the center position P of the region of interest of the object being collected.

[0087] In other words, when the X-ray source and detector are placed at any sampling point, the central ray emitted by the X-ray source is perpendicular to the sampling surface of the detector. The midpoint of the part of the central ray that penetrates the region of interest of the sampled object is the center position P of the region of interest of the sampled object.

[0088] In some embodiments, at any two sampling points, the center position P' of the region of interest of the two collected objects is determined respectively. Then, the midpoint of the line connecting the center positions P' of the two collected objects's regions of interest is determined as the center position P of the region of interest of the collected object.

[0089] In some embodiments, at several sampling points, the center position P' of the region of interest for a corresponding number of collected objects is determined. Then, the center positions P' of the regions of interest of several collected objects are connected, and their geometric center is determined as the center position P of the region of interest of the collected objects.

[0090] Step 102: After any one of the X-ray source and detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory according to the center position of the region of interest of the object being sampled and positions itself to the corresponding sampling point.

[0091] Specifically, the sampling point is located on the opposite side of the real-time vertical line between the X-ray source and the detector; this real-time vertical line passes through the center of the region of interest of the sampled object.

[0092] It should be noted that the X-ray source and detector can move along a free sampling trajectory, or they can move along a 180-degree + fan-angle semi-closed trajectory or a finite angle trajectory of a certain angle, as is used in the prior art.

[0093] For example, assuming that after the detector moves along the free sampling trajectory to any sampling point, the X-ray source moves along the free sampling trajectory until the sampling point is located at the center of the region of interest of the sampled object, where the real-time perpendicular line between the X-ray source and the detector passes through the sampling point. Then, this sampling point is the sampling point where the X-ray source needs to be located.

[0094] Conversely, if the X-ray source is moved first and then the detector is moved, the same process is used.

[0095] Furthermore, before the other device moves along the free sampling trajectory to the center position of the region of interest of the sampled object and is positioned at the corresponding sampling point, it continuously emits an audible and visual alarm during the movement along the free sampling trajectory. When it moves to the opposite side of the real-time vertical line between the X-ray source and the detector, the audible and visual alarm is deactivated.

[0096] For example, assuming the detector moves to any sampling point along the free sampling trajectory, the X-ray source continuously emits an audible and visual alarm during the process of moving to the corresponding sampling point along the free sampling trajectory, that is, informing the user that "the X-ray source has not yet moved to the corresponding sampling point". After moving to the corresponding sampling point, the audible and visual alarm is deactivated, that is, informing the user that "the X-ray source has moved to the corresponding sampling point and data can be collected".

[0097] Conversely, if the X-ray source is moved first and then the detector is moved, the same process is used.

[0098] In other words, the two ends of the real-time vertical line between the X-ray source and the detector are the two corresponding sampling points.

[0099] The deviation range of the real-time vertical line is ±5°.

[0100] After step 102, the method further includes: acquiring the spatial position information, angular velocity information and rotation angle information of the X-ray source and the detector respectively, for CT imaging after free sampling trajectory positioning.

[0101] Specifically, after the X-ray source and detector collect data at the corresponding sampling points, the collected data are reconstructed based on the spatial position information, angular velocity information and rotation angle information of the X-ray source and detector to obtain CT imaging of the free sampling trajectory.

[0102] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A free sampling trajectory localization method for CT imaging, applied in a CT device, the CT device comprising an X-ray source and a detector, characterized in that, The method includes: Determine the center location of the region of interest of the object being collected; After any one of the X-ray source and detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory and positions itself to the corresponding sampling point according to the center position of the region of interest of the object being sampled. Determining the center position of the region of interest of the target object specifically includes: determining a reference perpendicular line between the X-ray source and the detector, wherein the reference perpendicular line passes through the region of interest of the target object; and determining the center position of the region of interest of the target object based on the reference perpendicular line. Specifically, determining the reference perpendicular line between the X-ray source and the detector includes: when the central ray emitted by the X-ray source at any position is perpendicular to the acquisition surface of the detector, the central ray is the reference perpendicular line. Specifically, determining the center position of the region of interest of the collected object based on the reference vertical line includes: the midpoint of the portion of the reference vertical line that passes through the region of interest of the collected object is the center position of the region of interest of the collected object.

2. The free sampling trajectory localization method for CT imaging according to claim 1, characterized in that, After either the X-ray source or the detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory and positions itself to the corresponding sampling point based on the center position of the region of interest of the object being sampled. Afterward, the method further includes: acquiring the spatial position information, angular velocity information and rotation angle information of the X-ray source and the detector respectively, for CT imaging after free sampling trajectory positioning.

3. The free sampling trajectory localization method for CT imaging according to claim 2, characterized in that, The other device moves along a free sampling trajectory and positions itself to the corresponding sampling point based on the center position of the region of interest of the object being sampled. Specifically, the sampling point is located on the opposite side of the real-time vertical line between the X-ray source and the detector. The real-time vertical line passes through the center position of the region of interest of the object being sampled.

4. The free sampling trajectory localization method for CT imaging according to claim 3, characterized in that, The deviation range of the real-time vertical line is ±5°.

5. The free sampling trajectory localization method for CT imaging according to claim 4, characterized in that, The method further includes: before the other device moves along the free sampling trajectory according to the center position of the region of interest of the sampled object and is positioned to the corresponding sampling point, the other device continuously alarms with sound and light during the movement along the free sampling trajectory, and the alarm is deactivated when it moves to the opposite side of the real-time vertical line between the X-ray source and the detector.

6. A positioning system applying the free sampling trajectory positioning method for CT imaging as described in claim 1, characterized in that, The positioning system includes: a positioning unit and a data acquisition unit; The positioning unit is used to determine the position information of the X-ray source and the detector respectively based on the spatial position information, and to determine the center position of the region of interest of the object being collected; it is also used to determine that after any one of the X-ray source and the detector moves along the free sampling trajectory to any sampling point, the other device moves along the free sampling trajectory according to the center position of the region of interest of the object being collected and is positioned to the corresponding sampling point. The acquisition unit is used to acquire the spatial position information of the X-ray source and detector corresponding to the positioning unit and transmit it back to the positioning unit. The positioning unit is specifically used to determine a reference vertical line between the X-ray source and the detector, and the reference vertical line passes through the region of interest of the object being collected; and to determine the center position of the region of interest of the object being collected based on the reference vertical line.

7. The positioning system according to claim 6, characterized in that, The positioning system includes an audible and visual alarm unit, which is used to continuously sound and light alarms during the movement of another device along the free sampling trajectory before the other device moves along the free sampling trajectory according to the center position of the region of interest of the sampled object and positions itself to the corresponding sampling point. The audible and visual alarm is deactivated when the device moves to the opposite side of the real-time vertical line between the X-ray source and the detector.

8. The positioning system according to claim 6, characterized in that, The positioning unit is specifically used to take the opposite side of the real-time vertical line between the X-ray source and the detector as the corresponding sampling point; the real-time vertical line passes through the center of the region of interest of the sampled object.

9. A positioning system employing the free sampling trajectory positioning method for CT imaging as described in any one of claims 1-5, characterized in that, The system includes a positioning unit and a data acquisition unit; Two positioning units are provided, one on the X-ray source and the other on the detector. Two acquisition units are set up and located at any position around the X-ray source and detector, respectively.

10. The positioning system according to claim 9, characterized in that, The positioning unit includes a first main body and a first three-dimensional visual infrared marker. The first main body is disposed on an X-ray source or detector, and the first three-dimensional visual infrared marker is disposed on the top of the first main body along the X, Y, and Z axes, respectively.

11. The positioning system according to claim 9 or 10, characterized in that, The acquisition unit includes a second main body, a second three-dimensional visual infrared marker, and a binocular vision module. The second main body is set at any position around the X-ray source and detector. The second three-dimensional visual infrared marker is set on the top of the second main body along the X, Y, and Z axes, respectively. Two binocular vision modules are set and located on both sides of the second main body.

12. The positioning system according to claim 10, characterized in that, The positioning unit further includes a first gyroscope and a first angle sensor disposed on the first main body; the acquisition unit further includes a second gyroscope and a second angle sensor disposed on the second main body.

13. The positioning system according to claim 12, characterized in that, The system also includes a workstation, which is wirelessly connected to the positioning unit and the acquisition unit to record the position coordinates and angle information of all sampling points of the X-ray source and detector on the free sampling trajectory.

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