A large-field-of-view cone-beam CT imaging method, device, equipment, and storage medium

Abstract

Embodiments of the present invention relate to the field of cone-beam CT imaging, and disclose a large-field-of-view cone-beam CT imaging method, apparatus, device, and storage medium. A target is scanned around a scanning center according to a first sub-scanning path and a second sub-scanning path. During the scanning process, a main robotic arm and an auxiliary robotic arm drive a transmitting device and a receiving device to move synchronously so that the center of the cone imaging beam is always perpendicular to the center of the receiving device. The first sub-scanning path includes the center of the transmitting device deflecting from the direction of the cone imaging beam center to the scanning center in a preset direction by a preset angle and then rotating along a set trajectory. The second sub-scanning path includes the center of the transmitting device deflecting in the opposite direction of the preset direction by 2 times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the set trajectory. The scanning data at the same position are combined and then back-projected and reconstructed. X-ray energy can be efficiently utilized without changing the hardware equipment to achieve large-field-of-view cone-beam CT imaging.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of cone-beam CT imaging, and in particular to a large-field-of-view cone-beam CT imaging method, apparatus, device, and storage medium. Background Art

[0002] Cone beam CT imaging is used in orthopedic C-arms, vascular C-arms, image-guided radiotherapy systems, and industrial CT. The size of the reconstruction volume is limited by the detector size. In the field of industrial CT and radiotherapy, it is necessary to scan and reconstruct relatively large targets. Figure 1 As shown, S0 represents the ray source, D1D2 represents the detector, δ represents the effective fan beam angle, and D represents the distance from the ray source to the detector. S0D1D2 constitutes the geometric layout of the normal field of view scan. The scan reconstruction can be completed by rotating the object 360° with O1 as the scan center, and components with a radius less than or equal to r1 can be detected. When performing a biased wide field of view scan, the geometric layout of the scan remains unchanged, the scan center on the inspection table moves to O2, and the object rotates one circle, and objects with a radius less than or equal to r2 can be detected. This method uses the object offset to form a large field of view reconstruction. In order to simplify the mechanical design, industrial CT uses a method in which the object rotates on a turntable, but the tube and the flat panel do not move for scanning. However, traditional medical cone-beam CT uses a rack that rotates with the tube and the flat panel while the human body does not move for imaging. Mature medical cone-beam CT products translate the flat-panel detector along the width direction of the scan target (such as cone-beam CT imaging in radiotherapy equipment produced by Varian and Elekta), such as Figure 2 The geometric layout of the cone beam CT normal scan is shown. After the flat panel detector is translated, a large field of view scan can be performed. The geometric layout can be Figure 3 However, the applicant found that this solution has two problems: First, the beam limiter needs to be changed to change the range of X-rays emitted by the tube. Since the tube does not move, the photons and energy of the X-rays are the strongest in the central area, while gradually weakening in the surrounding area. After the flat panel detector is translated, for example Figure 3 In the cases shown in (2) and (3), the X-rays in the deviated area are used, but the Figure 3 The optimal area of ​​X-ray shown in (1); second, since the flat panel detector is biased, in order to form the reconstructed image, the rotation angle is increased, for example, Figure 3 In the case shown in (1), only 180° rotation plus the fan angle plus the fan angle α (see Figure 2 ),but Figure 3 The situations shown in (2) or (3) require a rotation angle of 360°, and increasing the rotation angle places higher requirements on the hardware. Summary of the Invention

[0003] The purpose of the present invention is to at least provide a large-field-of-view cone-beam CT imaging method, device, equipment and storage medium, which can at least solve the problem of efficiently utilizing X-ray energy to achieve large-field-of-view cone-beam CT imaging, and at least can achieve the goal of freely changing the positional relationship between the transmitting device and the receiving device relative to the scanning center around which the rotational motion is carried out without changing the hardware device (such as the beam limiter) to efficiently utilize X-ray energy and achieve large-field-of-view cone-beam CT imaging.

[0004] In order to solve the above technical problems, at least one embodiment of the present application provides a large-field-of-view cone-beam CT imaging method, which is implemented based on an image-guided radiotherapy system. The image-guided radiotherapy system includes a main robotic arm and an auxiliary robotic arm. The end of the main robotic arm is equipped with a transmitting device for transmitting a cone-shaped imaging beam, and the end of the auxiliary robotic arm is equipped with a receiving device for receiving the cone-shaped imaging beam; the large-field-of-view cone-beam CT imaging method includes: the main robotic arm and the auxiliary robotic arm respectively drive the transmitting device and the receiving device to scan the target around the scanning center according to a preset scanning path to obtain two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the cone-shaped imaging beam emitted by the transmitting device is formed. The center of the scanning path is always perpendicular to the center of the receiving device; the preset scanning path includes a first sub-scanning path and a second sub-scanning path, the first sub-scanning path includes the center of the transmitting device being deflected from the center of the conical imaging beam to the scanning center in a preset direction by a preset angle and then rotating along a set trajectory, the second sub-scanning path includes the center of the transmitting device being deflected in the opposite direction of the preset direction by 2 times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the set trajectory; the scanning data with the center of the transmitting device at the same position in the two sets of scanning data are combined to obtain a combined projection result; and back projection reconstruction is performed according to the combined projection results with the center of the transmitting device at different positions.

[0005] At least one embodiment of the present application further provides a large-field-of-view cone-beam CT imaging device, which is implemented based on an image-guided radiotherapy system. The image-guided radiotherapy system includes a main robotic arm and an auxiliary robotic arm, wherein a transmitting device for transmitting a cone-shaped imaging beam is installed at the end of the main robotic arm, and a receiving device for receiving the cone-shaped imaging beam is installed at the end of the auxiliary robotic arm; the large-field-of-view cone-beam CT imaging device includes: a rotating scanning control module, which is used to drive the transmitting device and the receiving device respectively through the main robotic arm and the auxiliary robotic arm to scan the target around the scanning center according to a preset scanning path to obtain two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the center of the cone-shaped imaging beam emitted by the transmitting device is always vertical at the center of the receiving device; the preset scanning path includes a first sub-scanning path and a second sub-scanning path, the first sub-scanning path includes the center of the emitting device deflecting from the center of the conical imaging beam to the direction of the scanning center in a preset direction by a preset angle and then rotating along a set trajectory, the second sub-scanning path includes the center of the emitting device deflecting at the end position of the first sub-scanning path in the opposite direction of the preset direction by a preset angle and then rotating in the opposite direction along the set trajectory; a scanning data combination module is used to combine the scanning data of the two sets of scanning data when the center of the emitting device is at the same position to obtain a combined projection result; a back projection reconstruction module is used to perform back projection reconstruction according to the combined projection results when the center of the emitting device is at different positions.

[0006] At least one embodiment of the present application also provides an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the above-mentioned large-field-of-view cone-beam CT imaging method.

[0007] At least one embodiment of the present application further provides a computer-readable storage medium storing a computer program, wherein the computer program implements the above-mentioned large-field-of-view cone-beam CT imaging method when executed by a processor.

[0008] Embodiments of the present application provide a large-field-of-view cone-beam CT imaging method that utilizes a dual-manipulator image-guided radiotherapy system. A main manipulator and a secondary manipulator, respectively, drive a transmitter and a receiver to rotate synchronously about a scanning center. Two sets of scan data for forming a large field of view are obtained by deflecting the center of the transmitter in a first direction by a preset angle and then rotating along a set trajectory. At the end of the first sub-scanning path, the center of the transmitter is deflected in the opposite direction of the preset direction by two times the preset angle and then rotating in the opposite direction along the set trajectory. The scan data obtained when the center of the transmitter is at the same position are combined to achieve scan sequencing. The combined data is then used for back-projection reconstruction to obtain a large-field-of-view reconstructed imaging result for the target. Compared to conventional large-field-of-view imaging solutions, the dual manipulators control the main manipulator and the secondary manipulator to drive the transmitter and the receiver to rotate synchronously about the scanning center, ensuring that the center of the cone-shaped imaging beam is always perpendicular to the center of the receiver. This eliminates the need to change hardware devices (such as beam limiters) and allows for the free adjustment of the positional relationship between the transmitter and the receiver relative to the scanning center around which the rotation occurs. This allows for efficient utilization of X-ray energy and achieves large-field-of-view cone-beam CT imaging.

[0009] In some optional embodiments, the preset angle is half of the fan angle. To improve the wide field of view imaging effect, the direction from the center of the cone imaging beam to the scanning center through the center of the transmitter is deflected to both sides, and the deflection angles on both sides are set to half of the fan angle, so that two sets of scanning data obtained when the center of the transmitter is at different positions are combined to cover the maximum field of view angle.

[0010] In some optional embodiments, the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data are combined, including: using a virtual receiving device to combine the projection images corresponding to the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data to obtain a combined projection result, the position of the virtual receiving device being determined based on the position of the receiving device in a first projection space and the position of the receiving device in a second projection space, the first projection space being the projection space formed when the center of the transmitting device is at any position on the first sub-scanning path, and the second projection space being the projection space formed when the center of the transmitting device is at that position on the second sub-scanning path. By combining the two projection images corresponding to the same position in the two sets of scanning data through the virtual receiving device, large field of view reconstruction can be simplified to a reconstruction process similar to that of a small field of view.

[0011] In some optional embodiments, a virtual receiving device is used to combine the two projection images corresponding to the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data to obtain a combined projection result, including: directly mapping each pixel point in the projection image corresponding to the first projection space and the second projection space to the virtual receiving device to obtain a first mapping result; or setting equidistantly distributed pixel positions for the virtual receiving device and reversely mapping the pixel positions to the projection images corresponding to the first projection space and the second projection space to obtain a second mapping result; splicing the two projection images in the first mapping result or the second mapping result to obtain a combined projection result, and processing the overlapping areas in the splicing in a weighted fusion manner. This pair of pixel sorting methods before back-projection reconstruction aligns the pixels corresponding to the real receiving device with the virtual receiving device one-to-one, or sets equidistantly distributed pixel positions for the virtual receiving device and then reversely maps these pixel positions to the projection image of the real receiving device. By implementing pixel sorting in this way, accurate reconstruction positions can be obtained, and thus accurate back-projection reconstruction results can be obtained.

[0012] In some optional embodiments, the back-projection reconstruction includes filtered back-projection reconstruction.

[0013] In some optional embodiments, the large-field-of-view cone-beam CT imaging method further includes: driving the transmitting device and the receiving device, respectively, by the main robotic arm and the auxiliary robotic arm to scan a geometric phantom placed at the scanning center along a preset scanning path around a scanning center to obtain two sets of scanning data, wherein during the scanning process, the transmitting device and the receiving device move synchronously so that the center of the cone imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device; the preset scanning path includes a first sub-scanning path and a second sub-scanning path, the first sub-scanning path including the center of the transmitting device being deflected from the direction of the cone imaging beam toward the scanning center in a preset direction by a preset angle and then rotating along a preset trajectory, and the second sub-scanning path including the center of the transmitting device being deflected in the opposite direction of the preset direction by two times the preset angle at the end position of the first sub-scanning path and then rotating along the preset trajectory in the opposite direction; combining the scanning data in the two sets of scanning data in which the center of the transmitting device is at the same position to obtain a combined projection result; and calculating a projection matrix at different positions based on the combined projection results in which the center of the transmitting device is at different positions and the coordinates on the geometric phantom, and determining the projection matrices at different positions as the geometric relationships at different positions. By scanning the geometric phantom in the same scanning manner as the real target scan reconstruction before scanning and reconstructing the real target, two sets of scanning data are obtained. The scanning data with the center of the transmitting device at the same position are combined to obtain a combined projection result. Combined with the coordinates on the geometric phantom, the projection matrix representing the geometric relationship of different positions can be calculated. This projection matrix provides accurate determination of the projection path during back-projection reconstruction.

[0014] In some optional embodiments, back-projection reconstruction is performed based on the combined projection results and geometric relationships of the center of the transmitting device at different positions. By precalculating the geometric relationship, the transmitting center and the receiving center can be accurately determined, and the geometric relationship of the phantom can be reconstructed, thereby improving the reconstruction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by the figures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments.

[0016] Figure 1 This is a schematic diagram of the large field of view scanning imaging principle of industrial CT in the existing technology;

[0017] Figure 2 This is a schematic diagram of the geometric layout of a normal medical cone-beam CT scan in the prior art;

[0018] Figure 3 This is a schematic diagram of the geometric layout of a large field of view scan after the flat panel detector is translated in the medical cone-beam CT in the prior art;

[0019] Figure 4 This is a flow chart of the large-field cone-beam CT imaging method provided in an embodiment of the present application;

[0020] Figure 5 is a schematic diagram of an image-guided radiotherapy system provided in an embodiment of the present application;

[0021] Figure 6 This is a schematic diagram of the positional relationship of the transmitting device at the bottom and the receiving device at the top provided in an embodiment of the present application;

[0022] Figure 7 This is Example 1 of the path between the transmitting device center and the receiving device center provided in an embodiment of the present application;

[0023] Figure 8 This is a schematic diagram of a large field of view imaging scan provided by an embodiment of the present application;

[0024] Figure 9 This is the second example of the path between the transmitting device center and the receiving device center provided in the embodiment of the present application;

[0025] Figure 10 This is the third example of the path between the transmitting device center and the receiving device center provided in the embodiment of the present application;

[0026] Figure 11 Schematic diagram of the positional relationship between the center of the tube, the center of the flat panel detector, and the line connecting the centers of the two at typical positions provided in the embodiment of the present application, wherein (a) and (b) correspond to Figure 9 Middle Path Example 2 Figure 10 Schematic diagram of the positional relationship between the center of the tube, the center of the flat panel detector, and the line connecting the two centers at a typical position in the middle path example three;

[0027] Figure 12 is a schematic diagram of a virtual receiving device provided in an embodiment of the present application;

[0028] Figure 13 This is a schematic diagram of mapping each pixel on a real receiving device to a virtual receiving device provided by an embodiment of the present application;

[0029] Figure 14 This embodiment of the present application provides Figure 13 A simplified example of;

[0030] Figure 15 This is a schematic diagram of reverse mapping on a real flat panel detector provided by an embodiment of the present application;

[0031] Figure 16 Schematic diagram of a large-field-of-view cone-beam CT imaging device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to solve the above-mentioned technical problem of efficiently utilizing X-ray energy to achieve large-field cone-beam CT imaging, the present invention proposes a large-field cone-beam CT imaging method. The implementation details of the large-field cone-beam CT imaging method of this embodiment are specifically described below. The following content is only for the convenience of understanding the implementation details provided by the present invention.

[0033] Example 1:

[0034] The large-field-of-view cone-beam CT imaging method of this embodiment can be applied to electronic devices with communication, computing, and data storage capabilities. The large-field-of-view cone-beam CT imaging method is implemented based on an image-guided radiotherapy system. The image-guided radiotherapy system includes a main robotic arm and an auxiliary robotic arm. The end of the main robotic arm is equipped with a transmitting device for transmitting a cone imaging beam, and the end of the auxiliary robotic arm is equipped with a receiving device for receiving a cone imaging beam. The specific process of the large-field-of-view cone-beam CT imaging method of this embodiment can be as follows: Figure 4 Shown, including:

[0035] In step 101, the main robotic arm and the auxiliary robotic arm drive the transmitting device and the receiving device respectively, and scan the target around the scanning center according to the preset scanning path to obtain two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the center of the conical imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device.

[0036] Specifically, the preset scanning path includes a first sub-scanning path and a second sub-scanning path. The first sub-scanning path includes the center of the emitting device deflecting from the center of the conical imaging beam to the direction of the scanning center in a preset direction by a preset angle and then rotating along a set trajectory. The second sub-scanning path includes the center of the emitting device deflecting in the opposite direction of the preset direction by 2 times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the set trajectory.

[0037] In some specific implementations, the preset direction includes a clockwise direction or a counterclockwise direction. After the center of the emitting device is deflected clockwise by 1 / 2 of the sector angle from the center of the cone imaging beam to the scanning center, it is rotated 180° plus the sector angle along the set trajectory around the scanning center. At the current position, the center of the emitting device is deflected counterclockwise by the sector angle and then rotated 180° plus the sector angle along the set trajectory in the opposite direction to obtain two sets of scanning data for forming a large field of view. The combination of the two sets of scanning data can cover a larger field of view angle, thereby realizing large-field cone-beam CT imaging. It should be understood that the center of the emitting device in the two sub-scanning paths can be deflected first to the clockwise direction or to the counterclockwise direction first. Since the set trajectory is fixed, only the deflection direction of the center of the emitting device in the two sub-scanning paths is different, and the actual large-field imaging result is not affected.

[0038] In some specific implementations, the preset angle is half of the fan angle. To improve the large field of view imaging effect, the angle of the center deflection of the preset transmitting device is set to half of the fan angle, so that the two sets of scanning data obtained when the center of the transmitting device is at different positions are combined to cover the maximum field of view angle.

[0039] In some examples, starting from an initial scanning position, a first sub-scanning path and a second sub-scanning path are sequentially executed. Specifically, at the initial scanning position, the center of the conical imaging beam emitted by the center of the transmitting device points toward the scanning center. Following the first sub-scanning path, the center of the transmitting device is deflected clockwise (counterclockwise) by 1 / 2 of a sector angle from the center of the conical imaging beam toward the scanning center, and then rotated along a predetermined trajectory by 180° plus the sector angle. At the current position, the center of the transmitting device is deflected counterclockwise (clockwise) by the sector angle, and then rotated in the opposite direction of the predetermined trajectory by 180° plus the sector angle, thereby obtaining two sets of scan data corresponding to the two sub-scanning paths. It should be understood that the deflection of the center of the transmitting device toward opposite directions in the two sub-scanning paths only changes the emission direction of the conical imaging beam and does not change the position of the center of the transmitting device. In actual applications, the center of the transmitting device needs to move along the predetermined trajectory to continuously change its position for scanning. Therefore, the center of the transmitting device executes the above-described predetermined scanning path around the scanning center to scan the target, thereby obtaining two sets of scan data.

[0040] When accurately locating a tumor before radiotherapy, the size of the reconstructed volume is limited by the size of the imaging device. In some scenarios, a larger reconstruction volume is required, such as chest and abdominal imaging. A larger field of view can also obtain better registration results. Therefore, this embodiment provides a solution for large-field cone-beam CT imaging based on dual robotic arms. Specifically, the main robotic arm and the auxiliary robotic arm respectively drive the transmitting device and the receiving device, and scan the target around the scanning center according to the first sub-scanning path and the second sub-scanning path to obtain two sets of scanning data. During the scanning process, the positional relationship between the transmitting device and the receiving device relative to the scanning center around which the rotational motion is carried out can be freely changed, so that the transmitting device and the receiving device move synchronously so that the center of the cone imaging beam emitted by the transmitting device is always perpendicular to that of the receiving device. Center, without changing the hardware equipment (such as beam limiter), X-ray energy can be efficiently utilized. After the center of the transmitting device is deflected in a preset direction by a preset angle, the transmitting device and the receiving device are rotated around the scanning center along the set trajectory by 180° plus the fan angle, and then the center of the transmitting device is deflected in the opposite direction of the preset direction by 2 times the preset angle, the transmitting device and the receiving device are rotated around the scanning center along the opposite direction of the set trajectory by 180° plus the fan angle, forming two sets of scanning data. The combination of these two sets of data can realize large-field cone-beam CT imaging. The deflection of the center of the transmitting device on the two sub-scanning paths can form two projection spaces with the direction of the center of the cone imaging beam pointing to the scanning center as the symmetry axis at the same position of the set trajectory, thereby forming large-field cone-beam CT imaging.

[0041] Step 102 : combining the scanning data in which the center of the emitting device is at the same position in the two sets of scanning data to obtain a combined projection result.

[0042] Step 103 , performing back-projection reconstruction based on the combined projection results when the center of the transmitting device is at different positions.

[0043] This embodiment provides a large-field-of-view cone-beam CT imaging method that utilizes a dual-manipulator image-guided radiotherapy system. The main and auxiliary manipulators, respectively, drive a transmitter and a receiver to rotate synchronously about a scanning center. The center of the transmitter deflects from the center of the cone-shaped imaging beam toward the scanning center in a predetermined direction by a predetermined angle and then rotates along a predetermined trajectory. The center of the transmitter then deflects in the opposite direction of the predetermined direction by twice the predetermined angle and then rotates in the opposite direction of the predetermined trajectory. Two sets of scan data are generated to form a large field of view. Scan data obtained when the center of the transmitter is at the same position are combined. Back-projection reconstruction is performed based on the combined projection results at different positions to obtain a large-field-of-view reconstructed imaging result for the target. Compared to existing large-field-of-view imaging solutions, the flexible control of the dual manipulators allows the main and auxiliary manipulators to drive the transmitter and receiver to rotate synchronously about the scanning center, ensuring that the center of the cone-shaped imaging beam is always perpendicular to the center of the receiver. This eliminates the need to change hardware (such as a beam limiter) and allows for flexible adjustment of the positional relationship between the transmitter and receiver relative to the scanning center around which the rotation occurs. This allows for efficient utilization of X-ray energy and achieves large-field-of-view cone-beam CT imaging.

[0044] Combining the scan data in which the center of the emitting device is at the same position in the two sets of scan data to obtain a combined projection result may further include:

[0045] Step 102a, using a virtual receiving device, combines the projection images corresponding to the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data. The position of the virtual receiving device is determined based on the position of the receiving device in the first projection space and the position of the receiving device in the second projection space. The first projection space is the projection space formed when the center of the transmitting device is at any position on the first sub-scanning path, and the second projection space is the projection space formed when the center of the transmitting device is at that position on the second sub-scanning path.

[0046] Through the virtual receiving device, the two projection images corresponding to the scan data at the same position in the two sets of scan data are combined to obtain a combined projection result, which can simplify the reconstruction of a large field of view into a reconstruction process similar to that of a small field of view.

[0047] In some embodiments, using a virtual receiving device, combining projection images corresponding to scan data in which the center of the transmitting device is at the same position in two sets of scan data to obtain a combined projection result further includes:

[0048] Directly mapping each pixel point in the projection images corresponding to the first projection space and the second projection space onto the virtual receiving device to obtain a first mapping result; or setting pixel positions of equal distance distribution on the virtual receiving device, and reversely mapping the pixel positions onto the projection images corresponding to the first projection space and the second projection space to obtain a second mapping result;

[0049] The two projection images in the first mapping result or the second projection result are spliced ​​to obtain a combined projection result, and the overlapping area is processed in a weighted fusion manner during the splicing.

[0050] This pair of pixel sorting methods before back-projection reconstruction matches the pixels corresponding to the real receiving device with the virtual receiving device one-to-one, or sets the virtual receiving device to equidistantly distributed pixel positions, and then reversely maps these pixel positions to the projection image of the real receiving device. In this way, pixel sorting can be achieved to obtain accurate reconstruction positions, and then obtain accurate back-projection reconstruction results.

[0051] In some embodiments, the large field-of-view cone-beam CT imaging method of this embodiment further includes:

[0052] The main robotic arm and the auxiliary robotic arm respectively drive the transmitting device and the receiving device to scan a geometric phantom placed at the scanning center around the scanning center according to a preset scanning path to obtain two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the center of the conical imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device. The preset scanning path includes a first sub-scanning path and a second sub-scanning path. The first sub-scanning path includes the center of the transmitting device being deflected from the center of the conical imaging beam to the scanning center in a preset direction by a preset angle and then rotating along a preset trajectory. The second sub-scanning path includes the center of the transmitting device being deflected in a direction opposite to the preset direction by two times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the preset trajectory. The scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data are combined to obtain a combined projection result.

[0053] According to the combined projection results of the center of the transmitting device at different positions and the coordinates on the geometric phantom, the projection matrices at different positions are calculated, and the projection matrices at different positions are determined as geometric relationships at different positions.

[0054] In a specific implementation, back-projection reconstruction is performed based on the combined projection results when the center of the transmitting device is at different positions and the aforementioned geometric relationship determined in advance by calculation.

[0055] By scanning the geometric phantom in the same scanning manner as the real target scan reconstruction before scanning and reconstructing the real target, two sets of scanning data are obtained. By combining the scanning data with the center of the transmitting device at the same position with the coordinates on the geometric phantom, the projection matrix representing the geometric relationship of different positions can be calculated. This projection matrix provides accurate determination of the projection path during back-projection reconstruction.

[0056] Example 2:

[0057] Based on the above embodiments, this embodiment is based on Figure 5 The image-guided radiotherapy system shown implements the method of the aforementioned embodiment, wherein a transmitting device 111 for transmitting a cone-shaped imaging beam is installed at the end of the main robotic arm 11, and a receiving device 121 for receiving the cone-shaped imaging beam is installed at the end of the auxiliary robotic arm 12. The transmitting device 111 may be an X-ray tube, and the receiving device 121 may be a flat-panel detector. In some examples, a treatment device 112 is also installed at the end of the main robotic arm 11, and the transmitting device 111 may be installed on the treatment device 112. The two robotic arms rotate synchronously around the scanning center (e.g., the center of the lesion), and while rotating, the tube emits a cone-shaped X-ray beam, and the flat-panel detector receives it synchronously to obtain multiple projection images. When the scanning angle is greater than 180° plus the fan angle, a cone-beam CT image can be obtained using a reconstruction algorithm. Figure 6 In the positional relationship shown, where the transmitting device 111 is at the bottom and the receiving device 121 is at the top, the dotted circle within the coverage range of the conical imaging beam emitted by the center 111 a of the transmitting device 111 represents the size of the reconstructed cross-section. Figure 7 is the rotation path of the center of the transmitting device 111 and the center of the receiving device 121 ( Figure 6 In order to distinguish the two rotation paths, the large arc A0-A1 is the rotation path of the center 111a of the transmitting device 111, and the small arc B0-B1 is the rotation path of the center of the receiving device 121. The two rotate synchronously around the scanning center (the intersection between the two dotted lines). The center 111a of the transmitting device 111 rotates from A0 to A1. Synchronously, the center of the receiving device 121 rotates from B0 to B1. The two are driven by the main robot arm 11 and the auxiliary robot arm 12 respectively. Based on this rotation path, it can be formed Figure 6 The reconstructed volume is represented by the dotted circle. Figure 7 At all positions on the two arcs, the X-ray beam emitted from the center of the tube is ensured to pass through the scanning center and then reach the center of the flat-panel detector vertically, which can be achieved through the synchronous motion control of the dual robotic arms. Figure 7The path shown is only an example. In actual applications, there may be multiple scanning paths. As long as the robot arm position is guaranteed to be reachable and there is no collision between the robot arms or between the robot arms and other objects, and the rotation angle is greater than 180° plus the fan angle, a cone-beam CT image can be formed.

[0058] In practical applications, it is often necessary to achieve scanning reconstruction with a larger field of view to obtain a larger reconstructed volume.

[0059] In order to form a reconstructed image with a large field of view and make the cross-section of the reconstructed object larger, the flexible and free movement and rotation of the robotic arm are used. The rotation center and the center of the reconstructed object remain unchanged. At the starting position of the scan, the tube first deflects 1 / 2 of the fan beam to one side (for example, clockwise), and the flat-panel detector moves to the corresponding position to ensure that the center of the beam is perpendicular to the center of the flat-panel detector, such as Figure 8 In the solid triangle area shown in , the tube deflects 1 / 2 of the fan beam to the other side (for example, counterclockwise), and the flat panel detector moves to the corresponding position to ensure that the center of the beam is perpendicular to the center of the flat panel detector, as shown in Figure 8 The dotted triangle area shown, Figure 8 The solid triangle and the dotted triangle form a large irradiation field, such as Figure 8 As shown in the solid circle area, the combined irradiation field rotates 180° around the rotation center and the combined fan angle can form a cone-beam CT image with a large field of view.

[0060] In order to achieve Figure 8 The scanning effect shown in the figure is that at the start of the scan, the tube first deflects 1 / 2 of the fan beam to one side (for example, from the center of the cone imaging beam to the scanning center in a clockwise direction), and the flat panel detector moves to the corresponding position to ensure that the center of the beam is perpendicular to the center of the flat panel detector, as shown in the figure. Figure 8 In the solid triangle area shown in , the tube and flat panel detector rotate synchronously around the scanning center by 180° plus the fan angle plus the fan angle. Figure 9 A schematic diagram of the rotation path of the tube center and the flat panel detector center. To distinguish, the large arc A0-A1 is the path of the tube center, and the small arc B0-B1 is the path of the flat panel detector center. A0 and B0 are Figure 8 The positions of the center of the tube and the center of the flat-panel detector are shown in the solid triangle area. The center of the tube rotates from A0 to A1, and synchronously, the center of the flat-panel detector rotates from B0 to B1. All positions on the two arcs try to ensure that the X-rays emitted from the center of the tube pass through the scanning center and reach the center of the flat-panel detector vertically. This effect can be achieved by relying on the synchronous motion control of the robotic arm. Figure 11(a) shows the positional relationship between the tube center, the flat-panel detector center, and the line connecting the two centers at three typical positions in the current rotation path. It can be seen that although the tube center and the flat-panel detector center are not directly opposite the center of the scanned object, the distance between the tube center and the scanned object center is unchanged, and the rotation path is still centered on the scan center. The same applies to the flat-panel detector center, so it is not repeated here.

[0061] After the previous rotation, the tube deflects 1 / 2 of the fan beam to the other side (for example, the center of the cone imaging beam points to the scanning center in the counterclockwise direction), and the flat panel detector moves to the corresponding position to ensure that the center of the beam is perpendicular to the center of the flat panel detector, such as Figure 8 In the dotted triangle area shown, the tube and flat panel detector rotate synchronously around the scanning center by 180° plus the fan angle. Figure 10 This is another diagram of the rotation path of the tube center and the flat panel detector center. To distinguish, let the large arc A0-A1 be the path of the tube center, and the small arc B0-B1 be the path of the flat panel detector center. A0 and B0 are Figure 8 The dotted triangle area shows the positions of the tube center and the flat-panel detector center. The tube center rotates from A0 to A1, and synchronously, the flat-panel detector center moves from B0 to B1. All positions between the two arcs try to ensure that the X-rays emitted by the tube center pass through the scanning center and then reach the flat-panel detector center vertically. This effect can be achieved by relying on the synchronous motion control of the robotic arm. Figure 11 (b) shows the positional relationship between the tube center, the flat-panel detector center, and the line connecting the two centers at three typical positions in the current rotation path. It can be seen that although the tube center and the flat-panel detector center are not directly facing the center of the scanned object, the distance between the tube center and the scanned object center is unchanged, and the rotation path is still centered on the scan center. The same applies to the flat-panel detector center, so it is not repeated here.

[0062] This embodiment also provides the following fast scanning path:

[0063] First, the center of the tube starts from Figure 9 A0 rotates along the arc path to Figure 9 A1, flat panel detector center synchronization from Figure 9 B0 rotates along the arc path to Figure 9 Then, the main and auxiliary manipulators rotate the tube and move it to the nearest position. Figure 9 A1 posture rotates to Figure 10 A1, that is, deflected to the other side (counterclockwise direction of the direction in which the center of the cone imaging beam points to the scanning center) by 1 / 2 fan angle, the center of the flat panel detector faces Figure 10 B1 in the figure, the center of the flat panel detector is closest to Figure 9 B1 moves to Figure 10B1, so that the center of the tube is Figure 10 The X-ray emitted by A1 is perpendicular to Figure 10 The center of the flat panel detector at B1; finally, the center of the tube from Figure 10 A1 rotates along the arc path to Figure 10 A0, the center of the flat panel detector is synchronized from Figure 10 B1 rotates along a circular path to Figure 10 B0; using this fast scanning path to complete cone-beam CT scanning with a large field of view.

[0064] Cone-beam CT reconstruction methods include direct filtered back-projection reconstruction and sorted back-projection reconstruction. Back-projection reconstruction can be performed using one of two methods: combining scan data obtained from scanning at the same tube center position. Back-projection involves evenly distributing the measured projection values ​​to each point along the original projection path. After back-projecting the projection values ​​in all directions, the back-projected images from each angle are accumulated. Filtered back-projection involves first performing a one-dimensional filter on the projection values ​​before back-projecting them, resulting in clearer contours in the reconstructed image.

[0065] The key to back-projection reconstruction is knowing the projection path. This means knowing the relationship between the coordinates of the reconstructed object and the center of the tube and the center of the flat-panel detector. This relationship is called the geometric relationship. Therefore, before back-projection reconstruction, the geometric relationship must be calculated, as shown in the following equation.

[0066]

[0067] Where, s represents the magnification factor (which is a dimensionless distance weighting factor), ( x , y , z ) represents the coordinates of the reconstructed volume space, ( u , v ) represents the projected image coordinates, P Represents a 3×4 projection matrix.

[0068] The process of solving the projection matrix is ​​called geometric correction. It can be solved using a geometric phantom. Given the coordinates (x, y, z) of the object points on the phantom and their positions (u, v) on the projected image, the projection matrix is ​​numerically solved. Each projection angle has its own projection matrix.

[0069] One implementation of back-projection reconstruction involves traversing the (x, y, z) coordinates of the reconstruction volume and calculating the corresponding (u, v) values ​​using the formula above: V(x, y, z) = F(u, v), where V represents the reconstruction volume and F represents the filtered projection image. In direct filtered back-projection reconstruction, if the geometric relationships are slightly off, some reconstructed positions may be superimposed multiple times, requiring weighted addition, with a total weight of 1.

[0070] In this embodiment, the implementation method of back-projection reconstruction after sorting can be adopted. The solid triangle and dotted triangle shown by the deflection of the tube and the flat panel detector to both sides are as shown in FIG. Figure 8 As shown, these two triangular fields of view are exactly solid great circles, Figure 6 In comparison, the scan data at the same position can be synthesized into a similar Figure 6 A circular area, such as Figure 12 The thick solid line in the figure shows a virtual detector. The scanning and reconstruction process is consistent with the traditional small field of view reconstruction process.

[0071] Figure 12 The position of the virtual receiving device 121a in the first projection space is determined based on the (real) receiving device position in the first projection space and the (real) receiving device position in the second projection space. The first projection space is the projection space formed when the center of the transmitting device is at any position on the first sub-scanning path ( Figure 8 The second projection space is the projection space formed when the center of the emitting device is at the position on the second sub-scanning path ( Figure 8 The virtual receiving device 121a is a side of a new triangle formed by the two sides representing the real receiving device in the solid triangle area and the dotted triangle area.

[0072] The position of each pixel on the real receiving device (real flat panel detector) mapped to the virtual receiving device (virtual flat panel detector) is the position where the center of the tube and the pixel connection line intersect on the virtual flat panel detector, such as Figure 13 As shown, the specific calculation can be done using Figure 14 A simplified example of . Figure 14 BC is the length of the flat-panel detector, A is the center of the tube, so the relationship between triangle ABC is known. D is a point on the actual flat-panel detector, and the distance CD is known. Find the length of CE. One solution process is as follows:

[0073] (1) Given ∠ACD, according to the cosine formula, AD 2 =AC 2 +CD 2 -2*AC*CD*cos(∠ACD) can calculate the distance of AD;

[0074] (2) According to the sine formula, CD / sin(∠CAE) = AD / sin(∠ACD), ∠CAE can be calculated;

[0075] (3) Given ∠ACE and ∠CAE, ∠AEC can be calculated. According to the sine formula: CE / sin(∠CAE) =AC / sin(∠AEC), CE can be calculated.

[0076] The above method directly maps the pixel size of the real flat panel detector to the virtual flat panel detector, and the pixels corresponding to the real receiving device are mapped one-to-one with the virtual receiving device. In this way, the pixel distances on the virtual flat panel detector are not equal, and the reconstruction calculation of non-equidistant pixels may be more complicated. Therefore, in order to simplify the reconstruction, this embodiment can also assume equidistant pixel positions on the virtual flat panel detector and reversely interpolate and map the pixel values ​​on the real flat panel detector, such as Figure 15 As shown, the dotted line connects the tube center and equidistant pixels on the virtual flat-panel detector. Given the length of CE, the length of CD is calculated using a similar solution as previously described. This pixel sorting method prior to back-projection reconstruction assigns equidistant pixel positions to the virtual receiving device and then reverse-maps these pixel positions to the projection image of the real receiving device. This yields accurate reconstructed positions and, consequently, accurate back-projection reconstruction results.

[0077] The scanning and reconstruction process of the method of the aforementioned embodiment in this embodiment is as follows:

[0078] (1) Place a large geometric phantom at the center of the scan;

[0079] (2) Scan the geometric phantom according to the fast scanning path to obtain two sets of scanning data;

[0080] Specifically, the fast scanning path includes: first, the center of the tube starts from Figure 9 A0 rotates along the arc path to Figure 9 A1, flat panel detector center synchronization from Figure 9 B0 rotates along the arc path to Figure 9 Then, the main and auxiliary manipulators rotate the tube and move it to the nearest position. Figure 9 A1 posture rotates to Figure 10 A1, that is, deflected to the other side (counterclockwise direction of the direction in which the center of the cone imaging beam points to the scanning center) by 1 / 2 fan angle, the center of the flat panel detector faces Figure 10 B1 in the figure, the flat panel detector is located near Figure 9 B1 moves to Figure 10 B1, so that the center of the tube is Figure 10 The X-ray emitted by A1 is perpendicular to Figure 10 The center of the flat panel detector at B1; finally, the center of the tube from Figure 10 A1 rotates along the arc path to Figure 10 A0, the center of the flat panel detector is synchronized from Figure 10 B1 rotates along a circular path to Figure 10 B0; using this fast scanning path to complete cone-beam CT scanning with a large field of view.

[0081] (3) Combine the scan data with the tube center at the same position. It should be understood that the two sets of data have the same spatial position of the tube center but different orientations. The scan data at the same position in the two sets of data correspond to two projection images. Since the distance between the objects on the geometric phantom is known, the two projection images can be synthesized into one image by image stitching. When stitching the images, a weighted addition is performed on the overlapping areas. Record the weighted values ​​under different virtual pixels.

[0082] (4) Calculate the geometric relationship: Given the projection image and the coordinates of the object on the geometric phantom, calculate the projection matrix according to formula (1).

[0083] (5) Repeat steps (3) and (4) at different tube center positions to obtain the corresponding projection matrix, and the geometric relationship is established.

[0084] (6) Place the scan object at the scanning center and scan the object according to the fast scanning path to obtain two sets of scanning data;

[0085] (7) Using the recorded weighted values ​​to combine the data in the manner of step (3), the data can be quickly combined;

[0086] (8) Perform filtered back-projection reconstruction according to the geometric relationship calculated in step (4);

[0087] (9) Repeat steps (7) and (8) for the scan data at different tube center positions to complete the reconstruction process.

[0088] Example 3:

[0089] Another embodiment of the present application relates to a large field of view cone-beam CT imaging device. The implementation details of the large field of view cone-beam CT imaging device of this embodiment are specifically described below. The following content is only provided for the convenience of understanding the implementation details of the present invention. The schematic diagram of the large field of view cone-beam CT imaging device of this embodiment can be as follows: Figure 16 As shown, the image-guided radiotherapy system is implemented based on the image-guided radiotherapy system, which includes a main robotic arm and an auxiliary robotic arm. The end of the main robotic arm is equipped with a transmitting device for transmitting a cone imaging beam, and the end of the auxiliary robotic arm is equipped with a receiving device for receiving the cone imaging beam. The large-field cone-beam CT imaging device includes a rotation scanning control module 301, a scanning data combination module 302, and a back-projection reconstruction module 303.

[0090] The rotational scanning control module 301 is configured to drive the transmitting device and the receiving device via the main and auxiliary robotic arms, respectively, to scan a target around a scanning center according to a preset scanning path, thereby obtaining two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the center of the conical imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device. The preset scanning path includes a first sub-scanning path and a second sub-scanning path. The first sub-scanning path includes the center of the transmitting device being deflected by a preset angle from the center of the conical imaging beam toward the scanning center in a preset direction and then rotating along a preset trajectory. The second sub-scanning path includes the center of the transmitting device being deflected by two times a preset angle in a direction opposite to the preset direction at the end of the first sub-scanning path and then rotating along the preset trajectory in the opposite direction. It should be understood that deflecting the center of the transmitting device by a preset angle toward either side of the direction from the center of the conical imaging beam toward the scanning center only changes the emission direction of the conical imaging beam and does not change the position of the center of the transmitting device. In practical applications, the position of the center of the transmitting device needs to be continuously changed for scanning. Therefore, the center of the transmitting device performs the above-described scanning of the target around the scanning center according to the preset scanning path to obtain two sets of scanning data.

[0091] The scanning data combining module 302 is configured to combine the scanning data in which the centers of the emitting devices are at the same position in the two sets of scanning data to obtain a combined projection result.

[0092] The back projection reconstruction module 303 is used to perform back projection reconstruction based on the combined projection results when the center of the transmitting device is at different positions.

[0093] In some specific implementations, the preset direction includes a clockwise direction or a counterclockwise direction. After the center of the emitting device is deflected clockwise by 1 / 2 of the sector angle from the center of the cone imaging beam to the scanning center, it is rotated 180° plus the sector angle along the set trajectory around the scanning center. At the current position, the center of the emitting device is deflected counterclockwise by the sector angle and then rotated 180° plus the sector angle along the set trajectory in the opposite direction to obtain two sets of scanning data for forming a large field of view. The combination of the two sets of scanning data can cover a larger field of view angle, thereby realizing large-field cone-beam CT imaging. It should be understood that the center of the emitting device in the two sub-scanning paths can be deflected first to the clockwise direction or to the counterclockwise direction first. Since the set trajectory is fixed, only the deflection direction of the center of the emitting device in the two sub-scanning paths is different, and the actual large-field imaging result is not affected.

[0094] In some specific implementations, the preset angle is half of the fan angle. To improve the large field of view imaging effect, the angle of the center deflection of the preset transmitting device is set to half of the fan angle, so that the two sets of scanning data obtained when the center of the transmitting device is at different positions are combined to cover the maximum field of view angle.

[0095] In some examples, starting from an initial scanning position, a first sub-scanning path and a second sub-scanning path are sequentially executed. Specifically, at the initial scanning position, the center of the conical imaging beam emitted by the center of the transmitting device points toward the scanning center. Following the first sub-scanning path, the center of the transmitting device is deflected clockwise (counterclockwise) by 1 / 2 of a sector angle from the center of the conical imaging beam toward the scanning center, and then rotated along a predetermined trajectory by 180° plus the sector angle. At the current position, the center of the transmitting device is deflected counterclockwise (clockwise) by the sector angle, and then rotated in the opposite direction of the predetermined trajectory by 180° plus the sector angle, thereby obtaining two sets of scan data corresponding to the two sub-scanning paths. It should be understood that the deflection of the center of the transmitting device toward opposite directions in the two sub-scanning paths only changes the emission direction of the conical imaging beam and does not change the position of the center of the transmitting device. In actual applications, the center of the transmitting device needs to move along the predetermined trajectory to continuously change its position for scanning. Therefore, the center of the transmitting device executes the above-described predetermined scanning path around the scanning center to scan the target, thereby obtaining two sets of scan data.

[0096] When accurately locating a tumor before radiotherapy, the size of the reconstructed volume is limited by the size of the imaging device. In some scenarios, a larger reconstruction volume is required, such as chest and abdominal imaging. A larger field of view can also obtain better registration results. Therefore, this embodiment provides a solution for large-field cone-beam CT imaging based on dual robotic arms. Specifically, the main robotic arm and the auxiliary robotic arm respectively drive the transmitting device and the receiving device, and scan the target around the scanning center according to the first sub-scanning path and the second sub-scanning path to obtain two sets of scanning data. During the scanning process, the positional relationship between the transmitting device and the receiving device relative to the scanning center around which the rotational motion is carried out can be freely changed, so that the transmitting device and the receiving device move synchronously so that the center of the cone imaging beam emitted by the transmitting device is always perpendicular to that of the receiving device. Center, without changing the hardware equipment (such as beam limiter), X-ray energy can be efficiently utilized. After the center of the transmitting device is deflected in a preset direction by a preset angle, the transmitting device and the receiving device are rotated around the scanning center along the set trajectory by 180° plus the fan angle, and then the center of the transmitting device is deflected in the opposite direction of the preset direction by 2 times the preset angle, the transmitting device and the receiving device are rotated around the scanning center along the opposite direction of the set trajectory by 180° plus the fan angle, forming two sets of scanning data. The combination of these two sets of data can realize large-field cone-beam CT imaging. The deflection of the center of the transmitting device on the two sub-scanning paths can form two projection spaces with the direction of the center of the cone imaging beam pointing to the scanning center as the symmetry axis at the same position of the set trajectory, thereby forming large-field cone-beam CT imaging.

[0097] The large-field-of-view cone-beam CT imaging device provided in this embodiment utilizes an image-guided radiotherapy system with dual robotic arms. The main and auxiliary robotic arms, respectively, drive a transmitter and a receiver to rotate synchronously about a scanning center. The center of the transmitter deflects from the center of the cone-shaped imaging beam toward the scanning center in a predetermined direction by a predetermined angle and then rotates along a predetermined trajectory. The center of the transmitter then deflects in the opposite direction of the predetermined direction by twice the predetermined angle and then rotates in the opposite direction of the predetermined trajectory. This generates two sets of scan data for a large field of view. Scan data obtained when the center of the transmitter is at the same position are combined. Back-projection reconstruction is performed based on the combined projection results at different positions to obtain a large-field-of-view reconstructed imaging result for the target. Compared to existing large-field-of-view imaging solutions, the flexible control of the dual robotic arms allows the main and auxiliary robotic arms to drive the transmitter and receiver to rotate synchronously about the scanning center, ensuring that the center of the cone-shaped imaging beam is always perpendicular to the center of the receiver. This eliminates the need to change hardware (such as a beam limiter) and allows for flexible adjustment of the positional relationship between the transmitter and receiver relative to the scanning center around which the rotation occurs. This allows for efficient utilization of X-ray energy and achieves large-field-of-view cone-beam CT imaging.

[0098] Combining the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data to obtain a combined projection result may further include: using a virtual receiving device to combine the projection images corresponding to the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data to obtain a combined projection result, wherein the position of the virtual receiving device is determined based on the position of the receiving device in the first projection space and the position of the receiving device in the second projection space, the first projection space is a projection space formed when the center of the transmitting device is at any position on the first sub-scanning path, and the second projection space is a projection space formed when the center of the transmitting device is at that position on the second sub-scanning path.

[0099] By combining two projection images corresponding to the scan data at the same position in the two sets of scan data through a virtual receiving device, the reconstruction of a large field of view can be simplified to a reconstruction process similar to that of a small field of view.

[0100] In some embodiments, using a virtual receiving device, combining projection images corresponding to scan data in which the center of the transmitting device is at the same position in two sets of scan data to obtain a combined projection result further includes:

[0101] Directly mapping each pixel point in the projection images corresponding to the first projection space and the second projection space onto the virtual receiving device to obtain a first mapping result; or setting pixel positions of equal distance distribution on the virtual receiving device, and reversely mapping the pixel positions onto the projection images corresponding to the first projection space and the second projection space to obtain a second mapping result;

[0102] The two projection images in the first mapping result or the second projection result are spliced ​​to obtain a combined projection result, and the overlapping area is processed in a weighted fusion manner during the splicing.

[0103] This pair of pixel sorting methods before back-projection reconstruction matches the pixels corresponding to the real receiving device with the virtual receiving device one by one, or sets the virtual receiving device to equidistantly distributed pixel positions, and then reversely maps these pixel positions to the projection image of the real receiving device, thereby achieving pixel sorting. In this way, accurate reconstruction positions can be obtained, and then accurate back-projection reconstruction results can be obtained.

[0104] In some embodiments, the large field of view cone-beam CT imaging apparatus further includes a geometric relationship calculation module for:

[0105] The main robotic arm and the auxiliary robotic arm respectively drive the transmitting device and the receiving device to scan a geometric phantom placed at the scanning center around the scanning center according to a preset scanning path to obtain two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the center of the conical imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device. The preset scanning path includes a first sub-scanning path and a second sub-scanning path. The first sub-scanning path includes the center of the transmitting device being deflected from the center of the conical imaging beam to the scanning center in a preset direction by a preset angle and then rotating along a preset trajectory. The second sub-scanning path includes the center of the transmitting device being deflected in a direction opposite to the preset direction by two times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the preset trajectory. The scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data are combined to obtain a combined projection result.

[0106] According to the combined projection results of the center of the transmitting device at different positions and the coordinates on the geometric phantom, the projection matrices at different positions are calculated, and the projection matrices at different positions are determined as geometric relationships at different positions.

[0107] In a specific implementation, back-projection reconstruction is performed based on the combined projection results when the center of the transmitting device is at different positions and the aforementioned geometric relationship determined in advance by calculation.

[0108] By scanning the geometric phantom in the same scanning manner as the real target scan reconstruction before scanning and reconstructing the real target, two sets of scanning data are obtained. By combining the scanning data with the center of the transmitting device at the same position with the coordinates on the geometric phantom, the projection matrix representing the geometric relationship of different positions can be calculated. This projection matrix provides accurate determination of the projection path during back-projection reconstruction.

[0109] It is worth mentioning that all modules involved in this embodiment are logical modules. In actual applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, to highlight the innovation of this application, this embodiment does not include units that are not closely related to solving the technical problem proposed by this application. However, this does not mean that other units do not exist in this embodiment.

[0110] Example 4:

[0111] Another embodiment of the present application relates to an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the large-field-of-view cone-beam CT imaging method of the above-mentioned embodiments.

[0112] The memory and processor are connected using a bus, which can include any number of interconnected buses and bridges. The bus connects various circuits of one or more processors and memories. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits. These are all well known in the art and are therefore not described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single component or multiple components, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over a wireless medium via an antenna. Furthermore, the antenna receives data and transmits it to the processor.

[0113] The processor is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory can be used to store data used by the processor when performing operations.

[0114] Embodiment 5:

[0115] Another embodiment of the present application relates to a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-mentioned large-field-of-view cone-beam CT imaging method embodiment.

[0116] That is, those skilled in the art will understand that all or part of the steps in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a program. The program is stored in a storage medium and includes a number of instructions for causing a device (which may be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, an optical disk, and other media that can store program code.

[0117] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A large-field-of-view cone-beam CT imaging method, implemented based on an image-guided radiotherapy system, wherein the image-guided radiotherapy system includes a main robotic arm and an auxiliary robotic arm, characterized in that: The end of the main robotic arm is equipped with a transmitting device for transmitting a conical imaging beam, and the end of the auxiliary robotic arm is equipped with a receiving device for receiving the conical imaging beam; The large-field-of-view cone-beam CT imaging method comprises: The main robotic arm and the auxiliary robotic arm respectively drive the transmitting device and the receiving device to scan the target around the scanning center according to a preset scanning path to obtain two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the center of the conical imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device. The preset scanning path includes a first sub-scanning path and a second sub-scanning path. The first sub-scanning path includes the center of the transmitting device being deflected from the center of the conical imaging beam to the scanning center in a preset direction by a preset angle and then rotating along a preset trajectory. The second sub-scanning path includes the center of the transmitting device being deflected in the opposite direction of the preset direction by two times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the preset trajectory. Using a virtual receiving device, the projection images corresponding to the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data are combined to obtain a combined projection result, including: directly mapping each pixel point in the projection image corresponding to the first projection space and the second projection space to the virtual receiving device to obtain a first mapping result; or setting equidistantly distributed pixel positions for the virtual receiving device, and reversely mapping them to the projection images corresponding to the first projection space and the second projection space according to the pixel positions to obtain a second mapping result; splicing the two projection images in the first mapping result or the second projection result to obtain a combined projection result; the position of the virtual receiving device is determined based on the position of the receiving device in the first projection space and the position of the receiving device in the second projection space, the first projection space being the projection space formed when the center of the transmitting device is at any position on the first sub-scanning path, and the second projection space being the projection space formed when the center of the transmitting device is at that position on the second sub-scanning path; Back-projection reconstruction is performed based on the combined projection results when the center of the emitting device is at different positions.

2. The large field of view cone-beam CT imaging method according to claim 1, characterized in that: The preset angle is half of the fan angle.

3. The large field of view cone-beam CT imaging method according to claim 1, characterized in that: During stitching, the overlapping areas are processed by weighted fusion.

4. The large field of view cone-beam CT imaging method according to claim 1, characterized in that: The back projection reconstruction includes filtered back projection reconstruction.

5. The large field of view cone-beam CT imaging method according to any one of claims 1 to 4, characterized in that: Also includes: The main robotic arm and the auxiliary robotic arm respectively drive the transmitting device and the receiving device to scan a geometric phantom placed at the scanning center around the scanning center according to a preset scanning path to obtain two sets of scanning data. During the scanning process, the transmitting device and the receiving device move synchronously so that the center of the conical imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device. The preset scanning path includes a first sub-scanning path and a second sub-scanning path. The first sub-scanning path includes the center of the transmitting device being deflected from the direction of the center of the conical imaging beam to the scanning center in a preset direction by a preset angle and then rotating along a preset trajectory. The second sub-scanning path includes the center of the transmitting device being deflected in the opposite direction of the preset direction by two times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the preset trajectory. Combining the scanning data in which the center of the emitting device is at the same position in the two sets of scanning data to obtain a combined projection result; According to the combined projection results of the center of the emitting device at different positions and the coordinates on the geometric phantom, the projection matrices at different positions are calculated, and the projection matrices at different positions are determined as geometric relationships at different positions.

6. The large field of view cone-beam CT imaging method according to claim 5, characterized in that: Back-projection reconstruction is performed based on the combined projection results when the center of the emitting device is at different positions and the geometric relationship.

7. A large-field-of-view cone-beam CT imaging device, implemented based on an image-guided radiotherapy system, wherein the image-guided radiotherapy system includes a main robotic arm and an auxiliary robotic arm, characterized in that: The end of the main robotic arm is equipped with a transmitting device for transmitting a conical imaging beam, and the end of the auxiliary robotic arm is equipped with a receiving device for receiving the conical imaging beam; The large-field cone-beam CT imaging device comprises: a rotational scanning control module, configured to drive the transmitting device and the receiving device via the main robotic arm and the auxiliary robotic arm, respectively, to scan a target around a scanning center according to a preset scanning path to obtain two sets of scanning data; during the scanning process, the transmitting device and the receiving device move synchronously so that the center of the conical imaging beam emitted by the transmitting device is always perpendicular to the center of the receiving device; the preset scanning path includes a first sub-scanning path and a second sub-scanning path, the first sub-scanning path includes the center of the transmitting device being deflected from the direction of the conical imaging beam toward the scanning center in a preset direction by a preset angle and then rotating along a preset trajectory; the second sub-scanning path includes the center of the transmitting device being deflected in a direction opposite to the preset direction by two times the preset angle at the end position of the first sub-scanning path and then rotating in the opposite direction along the preset trajectory; a scanning data combination module, configured to combine, using a virtual receiving device, the projection images corresponding to the scanning data in which the center of the transmitting device is at the same position in the two sets of scanning data to obtain a combined projection result, including: directly mapping each pixel point in the projection images corresponding to the first projection space and the second projection space onto the virtual receiving device to obtain a first mapping result; or setting equidistantly distributed pixel positions for the virtual receiving device, and reversely mapping them to the projection images corresponding to the first projection space and the second projection space according to the pixel positions to obtain a second mapping result; and splicing the two projection images in the first mapping result or the second projection result to obtain a combined projection result; the position of the virtual receiving device is determined based on the position of the receiving device in the first projection space and the position of the receiving device in the second projection space, the first projection space being the projection space formed when the center of the transmitting device is at any position on the first sub-scanning path, and the second projection space being the projection space formed when the center of the transmitting device is at that position on the second sub-scanning path; The back projection reconstruction module is used to perform back projection reconstruction based on the combined projection results when the center of the transmitting device is at different positions.

8. An electronic device, characterized in that: include: at least one processor; as well as, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the large-field-of-view cone-beam CT imaging method according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the large-field-of-view cone-beam CT imaging method according to any one of claims 1 to 6 is implemented.

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