Multi-robot image-guided radiotherapy system and its imaging method

Abstract

This invention relates to a multi-robot image-guided radiotherapy system and its imaging method, belonging to the field of radiotherapy technology. The multi-robot image-guided radiotherapy system of this invention includes a treatment device, a main robot, an auxiliary robot, and an imaging device. One or both of the radiation blocker and the imaging detector are movable, such that when emitting an imaging beam, the imaging detector can face the X-ray source while the radiation blocker faces away from the X-ray source, thus the radiation blocker does not obstruct the detection of the imaging detector; while when emitting a treatment beam, the radiation blocker can face the treatment device while the imaging detector faces away from the treatment device, thereby preventing the treatment beam from directly irradiating the imaging detector, thus protecting the imaging detector and ensuring the quality of the detected images.

Description

[0001] This application is a divisional application of CN 202410711955.1, filed on June 3, 2024, titled "Multi-robot image-guided radiotherapy system and imaging method thereof". TECHNICAL FIELD

[0002] The present application relates to the field of radiotherapy, in particular to a multi-robot image-guided radiotherapy system and an imaging method thereof. BACKGROUND

[0003] Image-guided radiotherapy technology is a technology that uses imaging equipment to monitor tumors and normal organs in real time before and during patient radiotherapy, corrects the displacement of the irradiation target area caused by positioning errors, adjusts the treatment range and treatment conditions according to the changes in the position and shape of the organs and target area, and makes the irradiation field "follow" the target area.

[0004] An image-guided radiotherapy device generally includes a treatment head, a blocking block, an image emitter, and an image receiver. The treatment head is used for tumor treatment, and the blocking block of high absorption material is opposite to the treatment head, so that the treatment beam emitted by the treatment head passes through the patient and reaches the center of the blocking block and is mostly absorbed by the blocking block. This has the advantage that the shielding requirement of the treatment room can be reduced. The image emitter is generally a kV-level X-ray ball tube, and the image receiver opposite to the ball tube is generally a flat panel detector, so that the emitted X-ray imaging beam is attenuated by different tissues in the human body and then accepted by the detector and converted into image information with tissue density.

[0005] Currently, image-guided radiotherapy systems are broadly classified into three categories based on their gantry configuration. The first category, the mainstream gantry configuration, places both the treatment head and imaging equipment on a circular gantry or C-arm, with the treatment beam and imaging beam intersecting at approximately 90°. Examples include Varian Halcyon and Elekta Versa HD. This type of equipment can only treat patients within a limited trajectory plane and at a limited patient distance, but this fixed gantry configuration provides better kV-CBCT (Cone Beam Computed Tomography) images. CBCT images can be registered with CT or MR images used in the treatment plan, allowing for adjustments to the treatment bed position based on the real-time patient location or modifications to the treatment plan for precise radiotherapy. The second category places the treatment head on a robotic arm, with the imaging system consisting of two X-ray tubes fixed to the ceiling and two flat panels fixed to the floor. An example is Acrylic's Cyberknife. This type of equipment offers flexible treatment trajectories, enabling radiotherapy at multiple spatial angles and distances. However, its image quality is inferior to the gantry configuration, and it cannot produce clearer three-dimensional images. To overcome the limitations of the first two types of equipment, a new type of radiotherapy device employs two robotic arms, enabling treatment of tumors at various angles and positions in space. The two robotic arms rotate synchronously to acquire kV-CBCT images, similar to the rotation of imaging equipment in a gantry configuration. This functionality is impossible with a single robotic arm or a single robot system. However, this new radiotherapy device suffers from the following problems in practical use: during treatment, the imaging device is directly irradiated by the high-energy treatment beam emitted by the device. This irradiation damages the imaging device's performance and produces persistent artifacts (afterglow) that are difficult to eliminate, thereby reducing image quality. Summary of the Invention

[0006] This invention provides a multi-robot image-guided radiotherapy system and its imaging method to solve at least one of the above-mentioned technical problems.

[0007] This invention provides an imaging method for a multi-robot image-guided radiotherapy system, comprising the following steps:

[0008] S100: Scan the geometric calibration phantom at a predetermined position to establish a pre-projection matrix associated with the imaging device of the multi-robot image-guided radiotherapy system;

[0009] S200: When performing imaging scanning on the target object, the pre-projection matrix is ​​used as the initial value, and the corrected projection matrix is ​​obtained by iterative calculation based on the feature points on the real-time projection image obtained by imaging scanning in the imaging area.

[0010] S300: Based on the corrected projection matrix, obtain the accurate spatial relationship of the reconstructed object and reconstruct a 3D image of the target object.

[0011] In one implementation, step S100 includes the following sub-steps:

[0012] S110: Perform a scan on the geometric calibration phantom at the predetermined position to establish a pre-projection matrix associated with the imaging device at each projection angle of the scan; or

[0013] S120: Perform multiple scans on the geometric calibration phantom at the predetermined position to establish multiple pre-projection matrices related to the imaging device at a certain projection angle, and select the pre-projection matrix with the highest probability among the multiple pre-projection matrices as the pre-projection matrix at that projection angle.

[0014] In one implementation, step S110 includes the following sub-steps:

[0015] S111: Place the geometric calibration phantom at the rotation center of the main robot and auxiliary robot of the multi-robot image-guided radiotherapy system;

[0016] S112: The main robot and the auxiliary robot rotate around the geometric calibration phantom according to a predetermined imaging path. The X-ray source of the imaging device rotates around the geometric calibration phantom with the main robot and emits an imaging beam onto the geometric calibration phantom, thereby obtaining a projected image of the geometric calibration phantom on the imaging detector of the imaging device that rotates with the auxiliary robot.

[0017] S113: Obtain the pre-projection matrix based on the projected image and the spatial coordinates of each marked point on the geometric calibration phantom.

[0018] In one implementation, step S120 includes the following sub-steps:

[0019] S121: Place the geometric calibration phantom at the rotation center of the main robot and auxiliary robot of the multi-robot image-guided radiotherapy system;

[0020] S122: The main robot and the auxiliary robot rotate around the geometric calibration phantom according to a predetermined imaging path. The X-ray source of the imaging device rotates with the main robot to a certain projection angle and emits an imaging beam to the geometric calibration phantom, thereby obtaining a projection image of the geometric calibration phantom at that projection angle on the imaging detector of the imaging device that rotates with the auxiliary robot.

[0021] S123: Obtain the pre-projection matrix based on the projected image at this projection angle and the spatial coordinates of each marked point on the geometric calibration phantom;

[0022] S124: Repeat steps S122 and S123 multiple times to obtain multiple pre-projection matrices under the projection angle, and select the pre-projection matrix with the highest probability among the multiple pre-projection matrices as the pre-projection matrix under the projection angle.

[0023] In one embodiment, during step S200, when the target object is scanned, the imaging detector and radiation blocker of the multi-robot image-guided radiotherapy system are moved to a position where the imaging detector is closer to the target object than the radiation blocker. Then, the X-ray source of the multi-robot image-guided radiotherapy system emits an imaging beam, which brings the imaging detector closer to the target object. The imaging beam can be detected and imaged by the imaging detector after passing through the target object.

[0024] In one embodiment, in step S200, the feature points on the real-time projected image include marker points on the support structure used to support the target object or marker points on the target object.

[0025] In one embodiment, the marking points of the geometric calibration phantom are non-transparent marking points, and the non-transparent marking points are arranged spirally along the axial direction of the geometric calibration phantom.

[0026] In one embodiment, in step S300, based on the corrected projection matrix, the accurate spatial relationship of the reconstructed object is obtained and the 3D image of the target object is reconstructed by using a filtered back projection method.

[0027] In one implementation, during step S200, when obtaining a real-time projected image within the imaging area, the distance between the imaging device of the multi-robot image-guided radiotherapy system and the target object is changed to alter the size of the imaging area.

[0028] The size of the X-ray source opening in the imaging device of the multi-robot image-guided radiotherapy system can be changed to alter the size of the imaging area.

[0029] The present invention also provides a multi-robot image-guided radiotherapy system for implementing the imaging method of the above-described multi-robot image-guided radiotherapy system, comprising:

[0030] A treatment device capable of emitting treatment beams;

[0031] The main robot is connected to the treatment device;

[0032] An auxiliary robot, on which a radiation blocker is connected; and

[0033] An imaging device includes an X-ray source capable of emitting an imaging beam and an imaging detector capable of detecting the imaging beam, wherein the X-ray source is disposed on the treatment device and the imaging detector is connected to the auxiliary robot or the radiation blocker.

[0034] The radiation blocker and the imaging detector are configured such that when the treatment device emits a treatment beam, the radiation blocker moves to face the treatment device and the imaging detector moves away from the treatment device; and when the X-ray source emits an imaging beam, the radiation blocker and the imaging detector move to face the X-ray source and the radiation blocker moves away from the X-ray source.

[0035] Compared with the prior art, the advantage of the present invention is that one or both of the radiation blocker and the imaging detector can be moved, such that when emitting the imaging beam, the imaging detector can face the X-ray source while the radiation blocker faces away from the X-ray source, so that the radiation blocker will not hinder the detection of the imaging detector; while when emitting the treatment beam, the radiation blocker can face the treatment device while the imaging detector faces away from the treatment device, so that the treatment beam will not directly irradiate the imaging detector, thereby protecting the imaging detector to ensure the quality of the image it detects. Attached Figure Description

[0036] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0037] Figure 1 This is a schematic diagram of the structure of the multi-robot image-guided radiotherapy system of the present invention;

[0038] Figure 2a yes Figure 1 The diagram shows the structure of the auxiliary robot.

[0039] Figure 2b This is a schematic diagram of the structure of the imaging detector and radiation blocker of the present invention installed in one of the installation methods;

[0040] Figure 2c This is a schematic diagram of the imaging detector and radiation blocker of the present invention installed in another mounting manner;

[0041] Figure 2d This is a schematic diagram of the imaging detector and radiation blocker of the present invention installed in yet another mounting manner;

[0042] Figure 3 This is a structural view of the treatment device emitting the treatment beam in the multi-robot image-guided radiotherapy system of the present invention;

[0043] Figure 4 This is a structural view of the imaging device emitting the imaging beam in the multi-robot image-guided radiotherapy system of the present invention;

[0044] Figure 5This is a schematic diagram of the motion trajectory of the imaging device in the multi-robot image-guided radiotherapy system of the present invention;

[0045] Figure 6 This is a schematic diagram of the projection image relationship of the imaging device of the multi-robot image-guided radiotherapy system of the present invention;

[0046] Figure 7a This is a circular trajectory deviation diagram of the imaging device of the multi-robot image-guided radiotherapy system of the present invention;

[0047] Figure 7b This is a circular trajectory deviation diagram of the imaging device of the multi-robot image-guided radiotherapy system of the present invention during synchronous control;

[0048] Figure 8 This is a schematic diagram of the geometric calibration phantom of the multi-robot image-guided radiotherapy system of the present invention;

[0049] Figure 9a , Figure 9b , Figure 9c This is a schematic diagram illustrating how changing the distance between the imaging device and the target object creates different imaging areas;

[0050] Figure 10a , Figure 10b , Figure 10c This is a schematic diagram showing how changing the distance between the imaging device and the target object, and changing the size of the opening of the X-ray source 105 of the imaging device, can create different imaging areas.

[0051] Figure 11a , Figure 11b , Figure 11c This is a schematic diagram of a biased imaging device to achieve a wider 3D-FOV.

[0052] Figure 12a , Figure 12b , Figure 12c This is a schematic diagram showing how changing the size of the opening of the X-ray source 105 of the imaging device alters the imaging area.

[0053] Figure label:

[0054] 101. Main robot; 102. Auxiliary robot; 103. Treatment device; 104. Radiation blocker; 105. X-ray source; 106. Imaging detector; 107. Base; 1071. Rotating shaft; 1072. U-shaped connector; 108. Telescopic window;

[0055] 1021. Front end; 1022. Forearm; 1023. Elbow joint; 1024. Upper arm; 1025. Shoulder joint;

[0056] 201. Treatment beam; 202. Imaging beam;

[0057] 301. Geometric calibration phantom; 302. Target object; 3011. Non-transmissive markers. Detailed Implementation

[0058] The invention will now be further described with reference to the accompanying drawings.

[0059] This invention provides a multi-robot image-guided radiotherapy system. More specifically, the multi-robot image-guided radiotherapy system of this invention is a novel dual-robot image-guided radiotherapy system, which may include two robots, a radiotherapy system, and an imaging system. The novel imaging system of this invention can perform CBCT imaging through the synchronous rotation of the two robots. To obtain clearer images, kV-level imaging detectors are generally used, and they are positioned closer to the patient to acquire projected images. However, a problem exists: during treatment, the imaging detector is directly irradiated by the high-energy treatment beam. This irradiation damages the performance of the imaging detector and produces artifacts (afterglow) that are difficult to eliminate over a long period of time, thereby reducing image quality.

[0060] The multi-robot image-guided radiotherapy system of the present invention can solve the above-mentioned technical problems.

[0061] Example 1

[0062] like Figures 1-4 As shown, the present invention provides a multi-robot image-guided radiotherapy system, including a treatment device 103, a main robot 101, an auxiliary robot 102, and an imaging device. Figure 1 and Figure 2a As shown, the treatment device 103 is connected to the main robot 101. The treatment device 103 can emit a treatment beam 201 to perform radiotherapy on a designated area of ​​the patient. The auxiliary robot 102 is located on the side of the treatment bed 111 opposite to the main robot 101, and a radiation blocker 104 is connected to it. By setting the radiation blocker 104, the treatment beam 201 emitted by the treatment device 103 passes through the patient and reaches the radiation blocker 104, and most of it can be absorbed by the radiation blocker 104, thus reducing the shielding requirements of the treatment room.

[0063] The imaging device includes an X-ray source 105 capable of emitting an imaging beam 202 and an imaging detector 106 capable of detecting the imaging beam 202. The X-ray source 105 is mounted on the treatment device 103, and the imaging detector 106 can be connected to an assistive robot 102 or a radiation blocker 104. The X-ray source 105 emits the imaging beam 202, which is detected and imaged by the imaging detector 106 after passing through the target object 302 (e.g., a human patient). This image can guide the treatment device 103; therefore, a high-quality imaging image is the foundation and guarantee for image-guided precision radiotherapy.

[0064] The present invention changes the orientation of the radiation blocker 104 and the imaging detector 106 by synchronizing their movements, thereby ensuring that the imaging detector 106 is not damaged when the treatment beam 201 is emitted and that the detection of the imaging detector 106 is not affected when the imaging beam 202 is emitted.

[0065] On the one hand, such as Figure 1 and Figure 3 As shown, the radiation blocker 104 and the imaging detector 106 are configured such that when the treatment device 103 emits the treatment beam 201, one or both of the radiation blocker 104 and the imaging detector 106 move to a position where the radiation blocker 104 faces the treatment device 103 and the imaging detector 106 faces away from the treatment device 103. That is, the radiation blocker 104 directly faces the treatment device 103, while the imaging detector 106 does not directly face the treatment device 103. When the radiation blocker 104 and the imaging detector 106 are in this position, the high-energy treatment beam 201 first passes through the radiation blocker 104, where a large amount of energy is absorbed before reaching the imaging detector 106. This avoids damage to the imaging detector 106 from direct high-energy radiation, thereby protecting the imaging detector 106.

[0066] On the other hand, such as Figure 1 and Figure 4 As shown, when the X-ray source 105 emits the imaging beam 202, one or both of the radiation blocker 104 and the imaging detector 106 move to a position where the imaging detector 106 faces the X-ray source 105 and the radiation blocker 104 faces away from the imaging detector 106. That is, the imaging detector 106 directly faces the X-ray source 105, while the radiation blocker 104 does not directly face the X-ray source 105. When the radiation blocker 104 and the imaging detector 106 are in this position, the imaging beam 202 is detected and imaged by the imaging detector 106 after passing through the target object 302. The image can guide the treatment, and because the radiation blocker 104 faces away from the X-ray source 105, it will not affect the detection of the imaging detector 106.

[0067] Furthermore, changing the orientation of the radiation blocker 104 and the imaging detector 106 can be achieved through their synchronized flipping motion.

[0068] In some alternative embodiments, such as Figure 2aAs shown, both the radiation blocker 104 and the imaging detector 106 are connected to the base 107 of the auxiliary robot 102, and the radiation blocker 104 and the imaging detector 106 are located on both sides of the base 107. The base 107 is rotatably connected to the front end of the auxiliary robot 102 (for example, through a shaft connection). Therefore, when the base 107 rotates relative to the auxiliary robot 102, it can drive the radiation blocker 104 and the imaging detector 106 to rotate, so that the radiation blocker 104 on one side rotates to face the treatment device 103, and the imaging detector 106 rotates to face away from the treatment device; or the imaging detector 106 on the other side rotates to face the X-ray source 105, and the radiation blocker 104 rotates to face away from the X-ray source.

[0069] The auxiliary robot 102 includes a large arm 1024 and a forearm 1022. One end of the large arm 1024 is connected to a shoulder joint 1025, and the other end is connected to the forearm 1022 via an elbow joint 1023. The end of the forearm 1022 is a front end 1021, and a base 107 is rotatably connected to the front end 1021. The large arm 1024 is movably connected to the shoulder joint 1025, thereby allowing it to rotate relative to the shoulder joint 1025. The large arm 1024 and the forearm 1022 are movably connected via the elbow joint 1023, so the forearm 1022 can rotate relative to either the large arm 1024 or the shoulder joint 1025, thereby adjusting the posture of the auxiliary robot 102.

[0070] The base 107 includes a rotating shaft 1071, which is connected to the radiation blocker 104 and the imaging detector 106. The base 107 also includes a U-shaped connector 1072 rotatably connected to the rotating shaft 1071, with its two ends connected to the two sides of the front end 1021. Therefore, the rotating shaft 1071 can rotate relative to either the U-shaped connector 1072 or the front end 1021 along its own axis.

[0071] When the rotating shaft 1071 rotates relative to the U-shaped connector 1072, the radiation blocker 104 and the imaging detector 106 can be rotated synchronously to the position shown. Figure 3 The radiation blocker 104 is shown facing the treatment device 103 to protect the position of the imaging detector 106; or, when the rotating shaft 1071 rotates in the opposite direction relative to the U-shaped connector 1072, the radiation blocker 104 and the imaging detector 106 can be rotated synchronously to the position shown. Figure 4 The imaging detector 106 shown is oriented toward the X-ray source 105 to perform the detection.

[0072] Furthermore, the U-shaped connector 1072 can also drive the rotating shaft 1071 to rotate relative to the front end 1021, and its rotation axis is perpendicular to the axis of the rotating shaft 1071. The front end 1021 can also be rotatably connected to the forearm 1022, so the front end 1021 can drive the U-shaped connector 1072 and the rotating shaft 1071 to rotate relative to the forearm 1022 about the axis of the front end 1021 itself, thereby changing the angle between the radiation blocker 104 and the imaging detector 106 and the treatment device 103 or the X-ray source 105.

[0073] In some alternative embodiments, the radiation blocker 104 can be configured to be connected to the base 107, and the imaging detector 106 can be disposed on the radiation blocker 104, such as... Figure 2b As shown, the imaging detector 106 and the radiation blocker 104 are at a certain angle (acute angle), which can also realize the synchronous flipping of the radiation blocker 104 and the imaging detector 106.

[0074] In the two optional embodiments described above, the base 107 can rotate relative to the auxiliary robot 102, thereby allowing the radiation blocker 104 and the imaging detector 106 to rotate synchronously by a certain angle, for example, they can rotate synchronously by 180°, thereby changing the original orientation of the radiation blocker 104 and the imaging detector 106.

[0075] In this invention, by synchronously flipping the radiation blocker 104 and the imaging detector 106 to change their orientation, a simpler auxiliary robot 102 can be formed. It can also greatly protect the imaging detector 106 when the treatment device 103 emits the treatment beam 201. During imaging, the imaging detector 106 can be easily and quickly restored to the required position, thereby ensuring a clearer projected image.

[0076] Furthermore, it is conceivable that changing the orientation of the radiation blocker 104 and the imaging detector 106 could also be achieved through their synchronized telescoping motion. For example... Figure 2c As shown, the imaging detector 106 is disposed in the radiation blocker 104. The radiation blocker 104 is provided with a telescopic window 108. When the X-ray source 105 emits the imaging beam 202, the telescopic window opens, and the imaging detector 106 extends out of the telescopic window to the outside of the radiation blocker 104 for detection. When the treatment device 103 emits the treatment beam 201, the imaging detector 106 retracts from the telescopic window into the inside of the radiation blocker 104, and the telescopic window closes simultaneously, thereby protecting the imaging detector 106.

[0077] Alternatively, in some other alternative embodiments, changing the orientation of the radiation blocker 104 and the imaging detector 106 can also be achieved by rotating the imaging detector 106 relative to the radiation blocker 104.

[0078] Specifically, the imaging detector 106 and the radiation blocker 104 are pivotally connected. For example, the side of the imaging detector 106 and the side of the radiation blocker 104 are rotatably connected by a pivot shaft 109 or a hinge, so that the imaging detector 106 can rotate along the pivot shaft 109, thereby changing the angle between it and the radiation blocker 104.

[0079] When the treatment device 103 emits the treatment beam 201, the imaging detector 106 can rotate until the angle between it and the radiation blocker 104 is 0° (i.e., they are parallel, please refer to...). Figure 2a Thus, the radiation blocker 104 faces the treatment device 103, while the imaging detector 106 faces away from the treatment device 103. The radiation blocker 104 covers the imaging detector 106 to protect it. Please refer to... Figure 2d As shown, when the X-ray source 105 emits the imaging beam 202, the imaging detector 106 rotates around the pivot axis 109. For example, the angle between the radiation blocker 104 and the imaging detector 106 is 90° (i.e., they are perpendicular) or a larger angle, so that the imaging detector 106 faces the X-ray source 105 and the radiation blocker 104 is away from the X-ray source 105 and does not block the imaging detector 106, so that the imaging detector 106 can receive the imaging beam 202.

[0080] The rotation of the imaging detector 106 can be achieved by a rotation drive on the base 107. For example, the base 107 is equipped with a rotation drive such as an electric cylinder or a pneumatic cylinder, which is connected to the imaging detector 106 and achieves the rotation of the imaging detector 106 around the pivot axis 109 by pushing or pulling the imaging detector 106. Alternatively, the imaging detector 106 can also be driven to rotate by the pivot axis 109.

[0081] It should be noted that, as described herein, radiation blocker 104 "facing" treatment device 103 means that radiation blocker 104 directly faces treatment device 103, thereby blocking the treatment beam 201. Imaging detector 106 "away from" treatment device 103 means that imaging detector 106 does not directly face treatment device 103. Similarly, imaging detector 106 "facing" X-ray source 105 means that imaging detector 106 directly faces X-ray source 105, and radiation blocker 104 "away from" X-ray source 105 means that radiation blocker 104 does not directly face X-ray source 105, in order to avoid blocking imaging beam 202.

[0082] The treatment device 103 is rotatably connected to the main robot 101. The X-ray source 105 is mounted on the treatment device 103, for example, it can be mounted at the front end of the treatment device 103 (i.e., the end closer to the target object 302). Alternatively, the X-ray source 105 can be mounted at other positions on the treatment device 103, as long as the imaging beam 202 emitted by the X-ray source 105 is not blocked by the treatment device 103.

[0083] In some alternative embodiments, the X-ray source 105 is tilted toward the treatment beam 201 emitted by the treatment device 103, such as... Figure 3 and Figure 4 As shown, this allows the imaging beam 202 emitted by the X-ray source 105 and the treatment beam 201 emitted by the treatment device 103 to virtually intersect at a certain location (e.g., the source-to-original distance SOD is 1 mm) (in reality, the X-ray source 105 and the treatment device 103 will not emit beams simultaneously). For example, the location of the virtual intersection could be the treatment center. The advantage of this is that the tumor location can be monitored while treating it, and in cases where the tumor is greatly affected by respiration, the tumor location can be precisely tracked for treatment.

[0084] Understandably, when the X-ray source 105 is installed at an angle so that the treatment beam 201 and the imaging beam 202 can virtually intersect (i.e., form a virtual angle between them), since it is necessary to ensure that the imaging beam 202 is perpendicular to the imaging detector 106, an angle can also be set between the radiation blocker 104 and the imaging detector 106, and the angle between the radiation blocker 104 and the imaging detector 106 is the same as the virtual angle, which can ensure that the imaging center of the imaging detector 106 is the treatment center.

[0085] In some alternative embodiments, the X-ray source 105 and the treatment device 103 can also be configured such that the imaging beam 202 emitted by the X-ray source 105 and the treatment beam 201 emitted by the treatment device 103 do not virtually intersect, and the imaging beam 202 and the treatment device 103 can even be virtually parallel. In this case, no angle needs to be set between the radiation blocker 104 and the imaging detector 106, thus facilitating the design and arrangement of the mechanical structure. For example... Figure 3 and Figure 4 As shown, the radiation blocker 104 includes a plate-shaped member that is parallel to and abuts against the plate-shaped imaging detector 106. In this case, the distance between the imaging beam 202 and the treatment beam 201 can be calculated and converted into the motion of the main robot 101, thereby ensuring that the imaging center is consistent with the treatment center, and achieving the effect of the radiation blocker 104 and the imaging detector 106 being installed at an angle as described in the above embodiment.

[0086] As described above, the multi-robot image-guided radiotherapy system of the present invention employs a dual-robot system. The main robot 101 and the auxiliary robot 102 each have their own control systems. To achieve the goals of treatment and imaging, the two robots need to move in coordination. During treatment, the main robot 101 irradiates the treatment location from different angles and with different doses according to the treatment plan. The auxiliary robot 102 moves along with the main robot 101 to ensure that the treatment beam 201, after passing through the treatment site, irradiates approximately the central area of ​​the radiation blocker 104. The absolute positional accuracy of the main robot 101 and the auxiliary robot 102 can be, for example, ±0.6 mm, which meets the requirement of a treatment accuracy of 1 mm.

[0087] Furthermore, the radiation blocker 104 can be a plate-like component, with its area designed to be larger to allow for sufficient precision and absorption of scattered radiation, ensuring that the positional accuracy errors of the main robot 101 and the auxiliary robot 102 are within design margins and can meet treatment requirements. The radiation blocker 104 can be made of radiation-resistant materials, such as heavy metals like lead.

[0088] like Figure 2a As shown, when the radiation blocker 104 and the imaging detector 106 are constructed as plate-shaped components, their bottom sides can be connected to the base 107 to achieve synchronous rotation. When the radiation blocker 104 is constructed as a cylindrical or disc-shaped structure, a fixing ring can be provided around its circumference, and the fixing ring is connected to the base 107 to realize the movement of the radiation blocker 104 as described in the above embodiments.

[0089] Example 2

[0090] like Figure 5 As shown, the X-ray source 105 of the imaging device emits an imaging beam 202, which forms a projected image on the imaging detector 106. Figure 6 As shown, the X-ray source 105 and the imaging detector 106 rotate around the imaging center (e.g., a human patient) with the main robot 101 and the auxiliary robot 102, respectively, and can obtain projection images at different projection angles. The reconstructed 3D image can be obtained by filtering and backprojecting the projection images at different angles.

[0091] In order to reconstruct a 3D image from a projected image, it is necessary to know accurately the geometric relationship between the 3D voxel coordinates of each projected image and the 2D pixel position on the imaging detector 106. The process of obtaining this geometric relationship is called geometric calibration, and this geometric relationship is the projection matrix.

[0092] Therefore, geometric relationships are a key factor determining the reconstruction quality of 3D images from CT (computed tomography) or CBCT (cone-beam computed tomography). In the multi-robot image-guided radiotherapy system of the present invention, which has a main robot 101 and an auxiliary robot 102, the treatment device 103 mounted on the main robot 101 and the radiation blocker 104 mounted on the auxiliary robot 102 are particularly heavy. Furthermore, the X-ray source 105 and imaging detector 106 of the imaging system are superimposed on the treatment device 103 and radiation blocker 104, respectively, resulting in a significant load on the main robot 101 and auxiliary robot 102, leading to slightly reduced dexterity. Additionally, the main robot 101 and auxiliary robot 102 are controlled independently, therefore the accuracy error is the sum of the errors of the two robots. Moreover, the main robot 101 and auxiliary robot 102 also exhibit path deviations when traversing circular trajectories, such as… Figure 7a As shown, in the two concentric rings, the innermost ring represents the target path of the imaging detector 106, and the outermost ring represents the target path of the X-ray source 105. The darker colored trajectory represents the actual trajectory of the X-ray source 105, and the lighter colored point trajectory represents the actual trajectory of the imaging detector 106. Figure 7b As shown, synchronous control of the main robot 101 and the auxiliary robot 102 was added, but the added synchronous control did not improve the deviation between the actual motion trajectory and the target trajectory. These deviations are caused by the X-ray source 105 and the imaging detector 106 deviating from their circular orbits in space, and because the deviation is different each time they rotate to the same position, it is difficult to establish the spatial position each time.

[0093] The geometric calibration method for CBCT imaging systems of the present invention aims to solve the problem of large errors in the position accuracy and position repeatability of multiple robots by obtaining reconstructed images without geometric errors.

[0094] Specifically, the geometric calibration method for the CBCT imaging system of the present invention includes the following steps.

[0095] S100: Scan the geometric calibration phantom 301 in the predetermined position to establish a pre-projection matrix associated with the imaging device of the multi-robot image-guided radiotherapy system.

[0096] As mentioned above, the main robot 101 and the auxiliary robot 102 will deviate from the predetermined track and position during movement, but the deviation is within a certain range. Therefore, the obtained pre-projection matrix is ​​also within the deviation range. Using it as the initial value of the iterative algorithm can accelerate the calculation process of the iterative algorithm.

[0097] In an optional implementation, S100 includes the following sub-steps;

[0098] S110: Perform a scan on the geometric calibration phantom 301 in the predetermined position to establish a pre-projection matrix associated with the imaging device of the multi-robot image-guided radiotherapy system at each projection angle of the scan.

[0099] More specifically, S110 includes the following sub-steps:

[0100] S111: Place the geometric calibration phantom 301 at the rotation center of the main robot 101 and auxiliary robot 102 of the multi-robot image-guided radiotherapy system.

[0101] S112: The main robot 101 and the auxiliary robot 102 rotate around the geometric calibration phantom 301 according to a predetermined imaging path. The X-ray source 105 of the imaging device rotates around the geometric calibration phantom 301 with the main robot 101 and emits an imaging beam onto the geometric calibration phantom 301, thereby obtaining the projected image (u,v) of the geometric calibration phantom on the imaging detector 106 of the imaging device that rotates with the auxiliary robot 102.

[0102] Geometric calibration phantom 301 Figure 8 As shown, non-transparent marking points 3011 are provided on it. The non-transparent marking points 3011 can be arranged spirally along the axis of the geometric calibration phantom 301, or arranged in other ways, such that the markings 301 are not in the same plane.

[0103] like Figure 6 As shown, the X-ray source 105 and the imaging detector 106 rotate around the rotation center O of the target object 302, with the coordinates of the rotation center O being (0,0,0). The spatial coordinates of a point on the target object 302 are (x,y,z), and the projection image of this point on the imaging detector 106 is (u,v). The projection relationship represented by the homogeneous coordinates of a point on the target object 302 is shown in formula (1).

[0104]

[0105] Where s is the magnification factor (a dimensionless distance weighting factor used to match the spatial coordinates (x, y, z) with the projected image (u, v)), and P is the 3×4 projection matrix (X-ray imaging direction information is mathematically expressed as a projection matrix. The projection matrix is ​​given in the form of a 3×4 matrix with real components, and can also be called the camera matrix. Geometrically, the 3×4 projection matrix represents a mapping or transformation from a set of three-dimensional points to a set of two-dimensional points). Therefore, given the magnification factor, as long as the projection matrix is ​​obtained, the spatial coordinates (x, y, z) of the target object 302 can be obtained, thus completing accurate 3D reconstruction.

[0106] The spatial coordinates of the i-th marker point 3011 on the geometric calibration phantom 301 are (x... i ,y i ,z i ), where 0≤i≤n, and n is the total number of marker points 3011 on the geometric calibration phantom 301. Since each marker point 3011 is a preset point on the geometric calibration phantom 301, it is the 3D spatial coordinates of each marker point 3011 {(x0,y0,z0),(x1,y1,z1),…,(x… i ,y i ,z i ), …,(x n ,y n ,z n The points 3011 are known on the geometric calibration phantom 301. The projected images of each marker point 3011 on the imaging detector 106 are {(u0,v0),(u1,v1),…,(u…}. i ,v i ), …, (u n ,v n The above projected images {(u0,v0),(u1,v1),…,(u...}} are... i ,v i ), …, (u n ,v n This can be obtained by detecting the center of the black dot on the projected image.

[0107] S113: Obtain the pre-projection matrix based on the spatial coordinates of each marker point 3011 on the projected image and the geometric calibration phantom 301.

[0108] Based on the above relationship (1), the algebraic matrix relationship between the spatial coordinates of each marked point on the projected image and the geometric calibration phantom 301 can be established, as shown in formula (2).

[0109]

[0110] Among them, the 3D spatial coordinates on the geometric calibration phantom 301 are {(x0,y0,z0),(x1,y1,z1),…,(x…} i ,y i ,z i ), …,(x n ,y n ,z n )} and projected images {(u0,v0),(u1,v1),…,(u i ,v i ), …, (u n ,v n All of these are known parameters, and the projection matrix can be calculated based on the above relation (2). This projection matrix is ​​the pre-projection matrix.

[0111] S200: When performing imaging scanning on the target object 302, the pre-projection matrix is ​​used as the initial value, and the corrected projection matrix is ​​obtained by iterative calculation based on the feature points on the real-time projection image obtained by imaging scanning in the imaging area.

[0112] When correcting the pre-projection matrix to obtain the corrected projection matrix, for example, P can be traversed within a certain range. ij The parameters are chosen such that the result on the left side of equation (2) is closest to 0. In some alternative implementations, the feature points on the real-time projection image include marker points on the support structure (e.g., treatment bed 111) used to support the target object 302. The marker points on the support structure supporting the target object 302 are displayed as highly attenuated black dots on the real-time projection image.

[0113] Due to the specific nature of radiotherapy, a treatment bed 111 with markers is typically used to facilitate the positioning of the target object 302 (human patient) or to simulate collision avoidance. These markers are evenly distributed on the treatment area near the treatment surface of the treatment bed 111. These markers are made of a high-absorption X-ray material, thus appearing as highly attenuated black dots in the projection image, which facilitates feature recognition in the projection image. The markers fixed on the treatment bed 111 can be the same as those on the geometric calibration phantom 301; that is, the spatial coordinates of these markers and their corresponding projection images are known parameters. Therefore, by analyzing the spatial coordinates of the markers and their corresponding projection images, the projection matrix can be obtained to obtain the accurate spatial position of the current image, thereby obtaining a high-quality reconstructed image.

[0114] In some alternative implementations, the feature points on the real-time projected image include marker points on the target object 302. The marker points on the target object 302 appear as highly attenuated black dots on the real-time projected image, which facilitates feature recognition on the projected image.

[0115] Due to the specific nature of radiotherapy, CT simulations are typically performed before the procedure. During this simulation, markers are placed on the target object 302 (the human patient). Both the orthogonal and lateral projections of these markers fall near the treatment center. These markers appear as highly attenuated black dots on the projected image. Therefore, these feature points can be used to iteratively correct the pre-projection matrix to obtain the accurate spatial location of the current image, resulting in a high-quality reconstructed image.

[0116] In some alternative implementations, feature points on the real-time projected image include prominent feature locations on the real-time projected image. In this alternative implementation, instead of using any marker points, prominent feature points (e.g., bone boundaries) on the projected image can be utilized, and the pre-projection matrix can be iteratively corrected by changes in feature points on nearby or adjacent projected images to obtain the accurate spatial location of the current image, thereby obtaining a high-quality reconstructed image.

[0117] It should be noted that when imaging the target object 302, the radiation blocker 104 on the auxiliary robot 102 of the multi-robot image-guided radiotherapy system and the imaging detector 106 of the imaging device move from a position where the radiation blocker 104 is closer to the target object 302 than the imaging detector 106 to a position where the imaging detector 106 is closer to the target object 302 than the radiation blocker 104, and then the target object 302 is imaged and scanned.

[0118] During treatment, to prevent the imaging detector 106 from being directly irradiated by the high-energy treatment beam 201 emitted by the treatment device 103 and damaged, the radiation blocker 104 and the imaging detector 106 of the imaging device are moved to a position where the radiation blocker 104 is closer to the target object 302 than the imaging detector 106. This allows the high-energy treatment beam 201 to pass through the radiation blocker 104 first, where a large amount of energy is absorbed before reaching the imaging detector 106, thus avoiding damage to the imaging detector 106. Therefore, when imaging the target object 302, the imaging detector 106 and the radiation blocker 104 need to be moved to a position where the imaging detector 106 is closer to the target object 302 than the radiation blocker 104 before the X-ray source 105 emits the imaging beam 202. This allows the imaging detector 106 to be closer to the target object 302, and the imaging beam 202 can be detected and imaged by the imaging detector 106 after passing through the target object 302.

[0119] S300: Based on the corrected projection matrix, reconstruct the 3D target object 302 using the filtered back projection method.

[0120] Based on the corrected projection matrix obtained in the above steps, the reconstructed 3D target object 302 can be obtained by filtering and backprojecting the projected image. For example, according to the above formula (2), the 3D spatial coordinates of the target object 302 are unknown parameters, while its projected image and the corrected projection matrix P are known parameters. Therefore, the 3D spatial coordinates of the target object 302 can be calculated according to the above relationship (2), and thus the reconstructed 3D target object 302 can be obtained.

[0121] Furthermore, the multi-robot image-guided radiotherapy system of the present invention can obtain reconstructed images without geometric errors through geometric calibration methods. Therefore, the multi-robot image-guided radiotherapy system of the present invention can also change the size of the imaging area. For example, when obtaining a real-time projected image within the imaging area, the distance between the imaging device and the target object 302 can be changed to change the size of the imaging area, or the size of the opening of the X-ray source 105 of the imaging device can be changed to change the size of the imaging area, thereby enabling the main robot 101 and the auxiliary robot 102 of the multi-robot image-guided radiotherapy system to move along arbitrary trajectories.

[0122] Since the dose attenuation of the X-ray source 105 is proportional to the square of the distance between it and the target object 302 when the aperture size of the X-ray source 105 remains constant, the smaller the imaging distance, the smaller the imaging area. Figure 9a , Figure 9b and Figure 9c As shown, the X-ray source 105 and the imaging detector 106 move simultaneously. The closer the X-ray source 105 gets to the target object 302, the farther the imaging detector 106 gets from the target object, and the smaller the imaging area becomes. This allows for more efficient use of the dose from the X-ray source 105 and the photosensitive area of ​​the imaging detector 106. Figure 10a , Figure 10b and Figure 10c As shown, moving the imaging detector 106 away from the target object 302, or moving the X-ray source 105 closer to the target object 302 and changing the opening size of the X-ray source 105, changes the imaging area, allowing for more efficient use of the dose of the X-ray source 105 and the photosensitive area of ​​the imaging detector 106.

[0123] Therefore, by reducing the imaging area, the same imaging effect can be achieved using lower emission energy. For example, when the human patient is obese or the power and heat of the X-ray source 105 are limited, reducing the imaging distance can increase the performance of the X-ray source 105.

[0124] like Figure 11a , Figure 11b and Figure 11c As shown, the X-ray source 105 and the imaging detector 106 move with the main robot 101 and the auxiliary robot 102, respectively, and can also achieve half-fan imaging to reconstruct a larger 3D-FOV. Figure 11a As shown, the X-ray source 105 and imaging detector 106 are not biased, their field of view (FOV) is 250 mm, and the diameter of the imaging area is D1 (400 mm). Figure 11b As shown, after the imaging detector 106 is biased, its FOV is larger, at 250 mm, and the diameter of the imaging area is D2 (310 mm). D2 is smaller than D1, as... Figure 11cAs shown, after the X-ray source 105 is biased, its FOV is larger, which is 500 mm, and the diameter of the imaging area is D1 (400 mm).

[0125] like Figure 12a , Figure 12b and Figure 12c As shown, the size of the X-ray source 105 opening can also be gradually reduced to decrease the imaging area.

[0126] The multi-robot image-guided radiotherapy system of this invention includes not only CBCT images, but also single-image and cinematic modes. Acquiring a projected image at a specific projection angle constitutes the single-image mode; continuously acquiring multiple single images while maintaining the same projection angle constitutes the cinematic image mode.

[0127] Example 3

[0128] Based on Embodiment 2 described above, the present invention also provides a modified Embodiment 3. The difference between Embodiment 3 and Embodiment 1 is that S120 is used instead of S110. The similarities between Embodiment 2 and Embodiment 1 will not be repeated.

[0129] Specifically, S120 involves scanning the geometric calibration phantom 301 at a predetermined position multiple times to establish multiple pre-projection matrices related to the imaging device of the multi-robot image-guided radiotherapy system at a certain projection angle, and selecting the pre-projection matrix with the highest probability among the multiple pre-projection matrices as the pre-projection matrix at that projection angle.

[0130] S120 includes the following sub-steps:

[0131] S121: Place the geometric calibration phantom 301 at the rotation center of the main robot 101 and auxiliary robot 102 of the multi-robot image-guided radiotherapy system.

[0132] S122: The main robot 101 and the auxiliary robot 102 rotate around the geometric calibration phantom 301 according to a predetermined imaging path. The X-ray source 105 of the imaging device rotates with the main robot 101 to a certain projection angle and emits an imaging beam to the geometric calibration phantom 301, thereby obtaining the projection image (u,v) of the geometric calibration phantom 301 at that projection angle on the imaging detector 106 of the imaging device that rotates with the auxiliary robot 102.

[0133] Geometric calibration phantom 301 Figure 8 As shown, non-transparent marking points 3011 are provided on it. The non-transparent marking points 3011 can be arranged spirally along the axis of the geometric calibration phantom 301, or arranged in other ways, such that the markings 301 are not in the same plane.

[0134] like Figure 6As shown, the X-ray source 105 and the imaging detector 106 rotate around the rotation center O of the target object 302, with the coordinates of the rotation center O being (0,0,0). The spatial coordinates of a point on the target object 302 are (x,y,z), and the projection image of this point on the imaging detector 106 is (u,v). The projection relationship represented by the homogeneous coordinates of a point on the target object 302 is shown in formula (1).

[0135]

[0136] Where s is the magnification factor (a dimensionless distance weighting factor used to match the spatial coordinates (x, y, z) with the projected image (u, v)), and P is the 3×4 projection matrix (X-ray imaging direction information is mathematically expressed as a projection matrix. The projection matrix is ​​given in the form of a 3×4 matrix with real components, and can also be called the camera matrix. Geometrically, the 3×4 projection matrix represents a mapping or transformation from a set of three-dimensional points to a set of two-dimensional points). Therefore, given the magnification factor, as long as the projection matrix is ​​obtained, the spatial coordinates (x, y, z) of the target object 302 can be obtained, thus completing accurate 3D reconstruction.

[0137] The spatial coordinates of the i-th marker point 3011 on the geometric calibration phantom 301 are (x... i ,y i ,z i ), where 0≤i≤n, and n is the total number of marker points 3011 on the geometric calibration phantom 301. Since each marker point 3011 is a preset point on the geometric calibration phantom 301, it is the 3D spatial coordinates of each marker point 3011 {(x0,y0,z0),(x1,y1,z1),…,(x… i ,y i ,z i ), …,(x n ,y n ,z n The points 3011 are known on the geometric calibration phantom 301. The projected images of each marker point 3011 on the imaging detector 106 are {(u0,v0),(u1,v1),…,(u…}. i ,v i ), …, (u n ,v n The above projected images {(u0,v0),(u1,v1),…,(u...}} are... i ,v i ), …, (u n ,v n This can be obtained by detecting the center of the black dot on the projected image.

[0138] S123: Obtain the pre-projection matrix based on the projected image at the projection angle and the spatial coordinates of each marker point 3011 on the geometric calibration phantom 301.

[0139] Based on the above relationship (1), the algebraic matrix relationship between the spatial coordinates of each marked point on the projected image and the geometric calibration phantom 301 can be established, as shown in formula (2).

[0140]

[0141] Among them, the 3D spatial coordinates on the geometric calibration phantom 301 are {(x0,y0,z0),(x1,y1,z1),…,(x…} i ,y i ,z i ), …,(x n ,y n ,z n )} and projected images {(u0,v0),(u1,v1),…,(u i ,v i ), …, (u n ,v n All of these are known parameters, and the projection matrix can be calculated based on the above relation (2). This projection matrix is ​​the pre-projection matrix.

[0142] S124: Repeat S122 and S123 multiple times to obtain multiple pre-projection matrices under the projection angle, and select the pre-projection matrix with the highest probability among the multiple pre-projection matrices as the pre-projection matrix under the projection angle.

[0143] Among multiple pre-projection matrices, the pre-projection matrix with the highest probability is the pre-projection matrix with the highest repeatability; or the pre-projection matrix with the highest probability among multiple pre-projection matrices is the pre-projection matrix with the smallest deviation between the actual running trajectory of the X-ray source and the imaging detector and the predetermined target path.

[0144] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A multi-robot image-guided radiotherapy system for implementing an imaging method of a multi-robot image-guided radiotherapy system, the imaging method comprising the following operation steps: S100: scanning a geometric calibration phantom (301) in a predetermined position to establish a pre-projection matrix related to an imaging device of the multi-robot image-guided radiotherapy system; S200: when performing an imaging scan on a target object (302), taking the pre-projection matrix as an initial value, and iteratively calculating a feature point on a real-time projection image obtained in the imaging scan in an imaging region to obtain a corrected projection matrix; S300: obtaining a reconstructed object accurate spatial relationship and reconstructing a 3D image of the target object (302) according to the corrected projection matrix; characterized in that The multi-robot image-guided radiotherapy system comprises: a treatment device (103) capable of emitting a treatment beam (201); a main robot (101) connected with the treatment device (103); a secondary robot (102) having a radiation blocker (104) connected thereto; and an imaging device comprising an X-ray source (105) capable of emitting an imaging beam (202) and an imaging detector (106) capable of detecting the imaging beam (202), the X-ray source (105) being arranged on the treatment device (103), and the imaging detector (106) being connected with the secondary robot (102) or the radiation blocker (104); wherein the radiation blocker (104) and the imaging detector (106) are configured to move to a position where the radiation blocker (104) faces the treatment device (103) and the imaging detector (106) faces away from the treatment device (103) when the treatment device (103) emits the treatment beam (201), and to move to a position where the imaging detector (106) faces the X-ray source (105) and the radiation blocker (104) faces away from the X-ray source (105) when the X-ray source (105) emits the imaging beam (202).

2. The multi-robot image guided radiotherapy system of claim 1, wherein, Step S100 comprises the following sub-steps: S110: scanning the geometric calibration phantom (301) in a predetermined position once to establish a pre-projection matrix related to the imaging device at each projection angle of the once scanning; or S120: scanning the geometric calibration phantom (301) in a predetermined position multiple times to establish multiple pre-projection matrices related to the imaging device at a certain projection angle, and selecting a pre-projection matrix with the highest probability among the multiple pre-projection matrices as the pre-projection matrix at the projection angle.

3. The multi-robot image guided radiotherapy system of claim 2, wherein, Step S110 comprises the following sub-steps: S111: placing the geometric calibration phantom (301) at the rotation center position of the main robot (101) and the secondary robot (102) of the multi-robot image-guided radiotherapy system; S112: the main robot (101) and the auxiliary robot (102) rotate around the geometric calibration phantom (301) according to a predetermined imaging path, the X-ray source (105) of the imaging device rotates around the geometric calibration phantom (301) with the main robot (101) and emits an imaging beam to the geometric calibration phantom (301), so as to obtain a projection image of the geometric calibration phantom on the imaging detector (106) of the imaging device rotating with the auxiliary robot (102); S113: a pre-projection matrix is obtained according to the projection image and the spatial coordinates of each marker point (3011) on the geometric calibration phantom (301).

4. The multi-robot image guided radiotherapy system of claim 2, wherein, Step S120 includes the following sub-steps: S121: the geometric calibration phantom (301) is placed at the rotation center position of the main robot (101) and the auxiliary robot (102) of the multi-robot image-guided radiotherapy system; S122: the main robot (101) and the auxiliary robot (102) rotate around the geometric calibration phantom (301) according to a predetermined imaging path, the X-ray source (105) of the imaging device rotates to a certain projection angle with the main robot (101) and emits an imaging beam to the geometric calibration phantom (301), so as to obtain a projection image of the geometric calibration phantom (301) at the projection angle on the imaging detector (106) of the imaging device rotating with the auxiliary robot (102); S123: a pre-projection matrix is obtained according to the projection image at the projection angle and the spatial coordinates of each marker point (3011) on the geometric calibration phantom (301); S124: steps S122 and S123 are repeated multiple times to obtain multiple pre-projection matrices at the projection angle, and the pre-projection matrix with the maximum probability is selected from the multiple pre-projection matrices as the pre-projection matrix at the projection angle.

5. The multi-robot image guided radiotherapy system of any of claims 1-4, wherein, In step S200, when the target object (302) is imaged, the imaging detector (106) and the radiation blocker (104) of the multi-robot image-guided radiotherapy system are moved to a position where the imaging detector (106) is closer to the target object (302) than the radiation blocker (104), and then the X-ray source (105) of the multi-robot image-guided radiotherapy system emits an imaging beam (202) again, so that the imaging detector (106) is closer to the target object (302), and the imaging beam (202) can be detected and imaged by the imaging detector (106) after passing through the target object (302).

6. The multi-robot image guided radiotherapy system of any one of claims 1-4, wherein, In step S200, the feature points on the real-time projection image include marker points on a support structure for supporting the target object (302) or marker points on the target object (302).

7. The multi-robot image guided radiotherapy system of claim 3, wherein, The marker points (3011) of the geometric calibration phantom (301) are radio-opaque marker points, and the radio-opaque marker points are arranged in a spiral along the axial direction of the geometric calibration phantom (301).

8. The multi-robot image guided radiotherapy system of claim 1, wherein, In step S300, according to the modified projection matrix, the accurate spatial relationship of the reconstructed object is obtained by the method of filtered back-projection, and the 3D image of the target object is reconstructed.

9. The multi-robot image guided radiotherapy system of any one of claims 1-4, wherein, In step S200, when the real-time projection image obtained in the imaging area, the distance between the imaging device of the multi-robot image-guided radiotherapy system and the target object (302) is changed to change the size of the imaging area, or The opening size of the X-ray source (105) of the imaging device of the multi-robot image-guided radiotherapy system is changed to change the size of the imaging area.

Images