Multi-robot image-guided radiotherapy system

Abstract

The invention relates to a multi-robot image-guided radiotherapy system, and relates to the technical field of radiotherapy. The multi-robot image guide radiotherapy system comprises a treatment device, a main robot, an auxiliary robot and an imaging device. The radiation blocker and the imaging detector are movable such that, when the imaging beam is emitted, the imaging detector can face the X-ray source and the radiation blocker deviates from the X-ray source, the radiation blocker does not interfere with the detection of the imaging detector; and when the treatment beam is emitted, the radiation blocker can face the treatment device, and the imaging detector deviates from the treatment device, so that the treatment beam cannot directly irradiate the imaging detector, and the purpose of protecting the imaging detector to ensure the quality of an image detected by the imaging detector is achieved.

Description

[0001] This application is a divisional application of Chinese patent CN 202410711955.1, whose application date is June 3, 2024 and whose name is “Multi-robot image-guided radiotherapy system and imaging method thereof”. Technical Field

[0002] The present invention relates to the technical field of radiotherapy, and in particular to a multi-robot image-guided radiotherapy system. Background Art

[0003] Image-guided radiotherapy technology uses imaging equipment to conduct real-time image monitoring of tumors and normal organs before and during patients' radiotherapy, correct the displacement of the irradiation target area caused by positioning errors, adjust the treatment range and conditions according to changes in the position and shape of the organs and target area, and allow the irradiation field to "follow" the target area.

[0004] Image-guided radiotherapy equipment generally includes a treatment head, a block, an image transmitter and an image receiver. The treatment head is used for tumor treatment. On the opposite side of the treatment head is a block made of highly absorbent material, so that the treatment beam emitted by the treatment head reaches the center of the block after passing through the patient and is mostly absorbed by the block. The benefit of this is that the shielding requirements for the treatment room can be reduced. The image transmitter is generally a kV-level X-ray tube, and the image receiver on the opposite side of the tube is generally a flat-panel detector, so that the emitted X-ray imaging beam is attenuated by different tissues of the human body and then received by the detector and converted into image information with tissue density.

[0005] At present, image-guided radiotherapy systems are roughly divided into three categories according to the form of the rack. The first category is the rack form of the current mainstream products, that is, the treatment head and imaging equipment are placed on a circular rack or C-shaped arm, and the treatment beam and imaging beam are crossed at approximately 90 degrees, such as Varian Halcyon and Elekta Versa HD. This type of equipment can only treat patients on a limited trajectory plane and a limited patient distance, but this fixed rack form can obtain better kV-CBCT (Cone Beam Computed Tomography) images. CBCT images can be registered with CT or MR images used in the treatment plan, and the position of the treatment bed can be moved according to the real-time patient position, or the treatment plan can be corrected to achieve precise radiotherapy. The second category is to place the treatment head on a robotic arm, and the image is composed of two tubes fixed to the ceiling and two flat plates fixed to the floor. For example, Cyberknife of Accuray, this device has a very flexible treatment trajectory and can perform radiotherapy at multiple spatial angles and different distances. The disadvantage is that the image quality is not as good as the rack form, and a clearer three-dimensional image cannot be obtained. In order to solve the limitations of the first two types of equipment, a new type of radiotherapy equipment currently available uses two robotic arms to treat tumors at various angles and positions in space, and the two robotic arms rotate synchronously to obtain kV-CBCT images, which is similar to the rotation of the imaging device in the rack form. This function cannot be achieved by a single robotic arm or a single robot system. This new type of radiotherapy equipment has the following problems in actual use, that is, during treatment, the imaging device will be directly irradiated by the high-energy treatment beam emitted by the treatment device, which will damage the performance of the imaging device and produce artifacts (afterglow) that are difficult to eliminate for a long time, thereby reducing the image quality. Summary of the invention

[0006] The present invention provides a multi-robot image-guided radiotherapy system for solving at least one of the above-mentioned technical problems.

[0007] The present invention provides a multi-robot image-guided radiotherapy system, comprising:

[0008] a treatment device capable of emitting a treatment beam;

[0009] a main robot connected to the treatment device;

[0010] an auxiliary robot having a radiation blocker connected thereto; and

[0011] an imaging device, comprising 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;

[0012] The radiation blocker and the imaging detector are configured such that when the treatment device emits a treatment beam, the radiation blocker and the imaging detector move to a point where the radiation blocker faces the treatment device and the imaging detector faces away from the treatment device; when the X-ray source emits an imaging beam, the radiation blocker and the imaging detector move to a point where the imaging detector faces the X-ray source and the radiation blocker faces away from the X-ray source;

[0013] The imaging detector is arranged on the radiation blocker, and an angle is formed between the imaging detector and the radiation blocker. The radiation blocker is connected to a base, and the base is rotatably connected to the front end of the auxiliary robot. When the base rotates relative to the auxiliary robot, the orientation of the radiation blocker can be flipped.

[0014] The radiation blocker comprises a plate-shaped member, and when the radiation blocker faces the treatment device, the plate-shaped member can completely block the imaging detector.

[0015] In one embodiment, the treatment device is rotatably connected to the main robot, and the X-ray source is disposed on the treatment device and is tilted toward a treatment beam emitted by the treatment device.

[0016] In one embodiment, the angle between the radiation blocker and the imaging detector is the same as the virtual angle between the treatment beam and the imaging beam.

[0017] In one embodiment, the treatment device is rotatably connected to the main robot.

[0018] In one embodiment, the auxiliary robot includes an upper arm and a lower arm, one end of the upper arm is connected to a shoulder joint, and the other end is connected to the lower arm through an elbow joint, the end of the lower arm is the front end, and the base is rotatably connected to the front end.

[0019] In one embodiment, the base includes a rotating shaft and a U-shaped connecting member rotatably connected to the rotating shaft, and two ends of the U-shaped connecting member are respectively connected to two sides of the front end.

[0020] In one embodiment, the rotating shaft can rotate along its own axis relative to the U-shaped connecting member or the front end, or

[0021] The U-shaped connecting piece can drive the rotating shaft to rotate relative to the front end, and its rotating axis is perpendicular to the axis of the rotating shaft.

[0022] In one embodiment, the front end is rotationally connected to the forearm, and the front end can drive the U-shaped connecting member and the rotating shaft to rotate relative to the forearm around the axis of the front end.

[0023] In one embodiment, the radiation blocker is made of a radiation-impermeable material.

[0024] 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 move, so that when emitting an imaging beam, the imaging detector can be directed toward the X-ray source and the radiation blocker can be directed away from the X-ray source, and the radiation blocker will not hinder the detection of the imaging detector; and when emitting a treatment beam, the radiation blocker can be directed toward the treatment device and the imaging detector can be directed 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Hereinafter, the present invention will be described in more detail based on embodiments and with reference to the accompanying drawings.

[0026] Figure 1 is a schematic structural diagram of a multi-robot image-guided radiotherapy system of the present invention;

[0027] Figure 2a yes Figure 1 The schematic diagram of the structure of the auxiliary robot shown;

[0028] Figure 2b It is a schematic diagram of the structure of the imaging detector and the radiation blocker of the present invention installed in one of the installation modes;

[0029] Figure 2c It is a schematic diagram of the structure of the imaging detector and the radiation blocker of the present invention installed in another installation manner;

[0030] Figure 2d is a schematic structural diagram of an imaging detector and a radiation blocker of the present invention installed in yet another installation manner;

[0031] Figure 3 is a structural view of a treatment device of a multi-robot image-guided radiotherapy system of the present invention emitting a treatment beam;

[0032] Figure 4 is a structural view of an imaging device of a multi-robot image-guided radiotherapy system of the present invention emitting an imaging beam;

[0033] Figure 5 is a schematic diagram of the motion trajectory of the imaging device of the multi-robot image-guided radiotherapy system of the present invention;

[0034] Figure 6 is a schematic diagram of the relationship between projection images of the imaging device of the multi-robot image-guided radiotherapy system of the present invention;

[0035] Figure 7ais a circular trajectory deviation diagram of an imaging device of a multi-robot image-guided radiotherapy system of the present invention;

[0036] Figure 7b It 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;

[0037] Figure 8 is a schematic structural diagram of a geometric calibration phantom of a multi-robot image-guided radiotherapy system of the present invention;

[0038] Figure 9a , Figure 9b , Fig.9c is a schematic diagram of changing the distance between the imaging device and the target object to form different imaging areas;

[0039] Fig.10a , Fig.10b , Fig.10c is a schematic diagram of changing the distance between the imaging device and the target object and changing the opening size of the X-ray source 105 of the imaging device to form different imaging areas;

[0040] Fig.11a , Fig.11b , Fig.11c is a schematic diagram of biasing an imaging device to achieve a larger range of 3D-FOV;

[0041] Fig.12a , Figure 12b , Fig.12c is a schematic diagram of changing the opening size of the X-ray source 105 of the imaging device to change the imaging area;

[0042] Reference numerals:

[0043] 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;

[0044] 1021, front end; 1022, forearm; 1023, elbow joint; 1024, upper arm; 1025, shoulder joint;

[0045] 201, treatment beam; 202, imaging beam;

[0046] 301. Geometric calibration phantom; 302. Target object; 3011. Radiopaque marker point. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the accompanying drawings.

[0048] The present invention provides a multi-robot image-guided radiotherapy system. More specifically, the multi-robot image-guided radiotherapy system of the present invention is a new dual-robot image-guided radiotherapy system, which may include two robots, a radiotherapy system, and an imaging system. The new imaging system of the present invention can perform CBCT imaging through the synchronous rotation of two robots. In order to obtain clearer images, kV-level imaging detectors are generally used, and they are arranged closer to the patient to obtain projection images. However, there is a problem that the imaging detector will be directly irradiated by the high-energy treatment beam during treatment, which will damage the performance of the imaging detector and produce artifacts (afterglow) that are difficult to eliminate for a long time, thereby reducing the image quality.

[0049] The multi-robot image-guided radiotherapy system of the present invention can solve the above technical problems.

[0050] Example 1

[0051] like Figure 1-Figure 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, and the treatment device 103 can emit a treatment beam 201 to perform radiotherapy on a specified area of ​​the patient. The auxiliary robot 102 is arranged on a side of the treatment bed 111 opposite to the main robot 101, and is connected to a radiation blocker 104. By arranging the radiation blocker 104, the treatment beam 201 emitted by the treatment device 103 reaches the radiation blocker 104 after passing through the patient, and most of it can be absorbed by the radiation blocker 104, thereby reducing the shielding requirements for the treatment room.

[0052] 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, wherein the X-ray source 105 is disposed on the treatment device 103, and the imaging detector 106 can be connected to the auxiliary robot 102 or the radiation blocker 104. The X-ray source 105 can emit an 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), and the imaging image can guide the treatment device 103, so an imaging image with good quality is the basis and guarantee of image-guided precision radiotherapy.

[0053] The present invention changes the orientation of the radiation blocker 104 and the imaging detector 106 by making them move synchronously, thereby ensuring that the imaging detector 106 will not be damaged when the treatment beam 201 is emitted, and the detection of the imaging detector 106 will not be affected when the imaging beam 202 is emitted.

[0054] On the one hand, if Figure 1 and Figure 3 As shown, the radiation blocker 104 and the imaging detector 106 are constructed so 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 such a position, the high-energy treatment beam 201 first passes through the radiation blocker 104 and is absorbed by the radiation blocker 104, and then reaches the imaging detector 106, thereby preventing the imaging detector 106 from being damaged by direct exposure to high energy, thereby achieving the purpose of protecting the imaging detector 106.

[0055] On the other hand, 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 such a position, the imaging beam 202 is detected and imaged by the imaging detector 106 after passing through the target object 302, and the imaged image can guide the treatment, and since the radiation blocker 104 faces away from the X-ray source 105, it will not affect the detection of the imaging detector 106.

[0056] Furthermore, changing the orientation of the radiation blocker 104 and the imaging detector 106 can be achieved by a synchronous flipping motion of the two.

[0057] In some optional embodiments, such as Figure 2a As shown, the radiation blocker 104 and the imaging detector 106 are both connected to the base 107 of the auxiliary robot 102, and the radiation blocker 104 and the imaging detector 106 are respectively located on both sides of the base 107, and the base 107 is rotatably connected to the front end of the auxiliary robot 102 (for example, the rotatable connection is achieved through an axis connection, etc.). 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 flip over, so that the radiation blocker 104 on one side is flipped to face the treatment device 103, and the imaging detector 106 is synchronously flipped to face away from the treatment device; or the imaging detector 106 on the other side is flipped to face the X-ray source 105, and the radiation blocker 104 is synchronously flipped to face away from the X-ray source.

[0058] The auxiliary robot 102 includes an upper arm 1024 and a lower arm 1022, wherein one end of the upper arm 1024 is connected to a shoulder joint 1025, and the other end is connected to the lower arm 1022 through an elbow joint 1023, the end of the lower arm 1022 is a front end 1021, and the base 107 is rotatably connected to the front end 1021. The upper arm 1024 is movably connected to the shoulder joint 1025, so that it rotates relative to the shoulder joint 1025, and the upper arm 1024 and the lower arm 1022 are movably connected through the elbow joint 1023, so that the lower arm 1022 can rotate relative to the upper arm 1024 or the shoulder joint 1025, so that the posture of the auxiliary robot 102 can be adjusted.

[0059] The base 107 includes a rotating shaft 1071, which is respectively 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, and the two ends of the U-shaped connector 1072 are respectively connected to the two sides of the front end 1021. Therefore, the rotating shaft 1071 can rotate relative to the U-shaped connector 1072 or the front end 1021 along its own axis.

[0060] When the rotating shaft 1071 rotates relative to the U-shaped connecting member 1072, the radiation blocker 104 and the imaging detector 106 can be synchronously rotated to the position as shown in FIG. Figure 3 The radiation blocker 104 shown in FIG. 1 is oriented toward the treatment device 103 to protect the imaging detector 106; or when the rotating shaft 1071 rotates in the opposite direction relative to the U-shaped connecting member 1072, the radiation blocker 104 and the imaging detector 106 can be rotated synchronously to the position shown in FIG. Figure 4 An imaging detector 106 is shown oriented toward the X-ray source 105 to perform detection.

[0061] In addition, the U-shaped connector 1072 can also drive the rotating shaft 1071 to rotate relative to the front end 1021, and its rotating axis is perpendicular to the axis of the rotating shaft 1071. The front end 1021 and the small arm 1022 can also be rotatably connected, so the front end 1021 can drive the U-shaped connector 1072 and the rotating shaft 1071 to rotate relative to the small arm 1022 around the axis of the front end 1021, 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.

[0062] In some optional embodiments, the radiation blocker 104 may be arranged to be connected to the base 107, and the imaging detector 106 may be arranged on the radiation blocker 104. Figure 2b As shown, the imaging detector 106 and the radiation blocker 104 are at a certain angle (acute angle), and the radiation blocker 104 and the imaging detector 106 can also be flipped synchronously.

[0063] In the above two optional embodiments, the base 107 can rotate relative to the auxiliary robot 102, so that the radiation blocker 104 and the imaging detector 106 can rotate synchronously by a certain angle, for example, the two can rotate synchronously by 180°, thereby changing the original orientation of the radiation blocker 104 and the imaging detector 106.

[0064] In the present invention, by synchronously flipping the radiation blocker 104 and the imaging detector 106 to change their orientations, an auxiliary robot 102 with a simpler structure can be formed, and the imaging detector 106 can be greatly protected when the treatment device 103 emits the treatment beam 201. When imaging, the imaging detector 106 can be easily and quickly restored to the desired position, thereby ensuring a clearer projection image.

[0065] Furthermore, it is conceivable that changing the orientation of the radiation blocker 104 and the imaging detector 106 can also be achieved by synchronously extending and retracting the two. Figure 2c As shown, the imaging detector 106 is arranged in the radiation blocker 104, and a telescopic window 108 is arranged on the radiation blocker 104. When the X-ray source 105 emits the imaging beam 202, the telescopic window is opened, and the imaging detector 106 is synchronously extended from 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 is retracted from the telescopic window into the inside of the radiation blocker 104, and the telescopic window is synchronously closed, thereby protecting the imaging detector 106.

[0066] Alternatively, in some other optional embodiments, changing the orientation of the radiation blocker 104 and the imaging detector 106 may also be achieved by rotating the imaging detector 106 relative to the radiation blocker 104 .

[0067] Specifically, the imaging detector 106 is pivotally connected to the radiation blocker 104. 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 the imaging detector 106 and the radiation blocker 104.

[0068] When the treatment device 103 emits the treatment beam 201, the imaging detector 106 can be rotated to an angle of 0° between it and the radiation blocker 104 (ie, the two are parallel, see Figure 2a ), so that the radiation blocker 104 faces the treatment device 103, and the imaging detector 106 faces away from the treatment device 103, and the radiation blocker 104 covers the imaging detector 106 to protect the imaging detector 106; please refer to Figure 2dAs 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., the two are perpendicular) or a larger angle, so that the imaging detector 106 faces the X-ray source 105, the radiation blocker 104 turns 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.

[0069] The rotation of the imaging detector 106 can be achieved by a rotating drive member on the base 107. For example, a rotating drive member such as an electric cylinder or a pneumatic cylinder is provided on the base 107, which is connected to the imaging detector 106, and the imaging detector 106 is pushed or pulled to achieve the rotation of the imaging detector 106 around the pivot shaft 109. Alternatively, the imaging detector 106 can also be driven to rotate by the pivot shaft 109.

[0070] It should be noted that the radiation blocker 104 described herein “facing” the treatment device 103 means that the radiation blocker 104 directly faces the treatment device 103, thereby blocking the treatment beam 201, and the imaging detector 106 “facing away from” the treatment device 103 means that the imaging detector 106 does not directly face the treatment device 103. Similarly, the imaging detector 106 “facing” the X-ray source 105 means that the imaging detector 106 directly faces the X-ray source 105, and the radiation blocker 104 facing away from the X-ray source 105 means that the radiation blocker 104 does not directly face the X-ray source 105, so as to avoid blocking the imaging beam 202.

[0071] The treatment device 103 is rotatably connected to the main robot 101, and the X-ray source 105 is disposed on the treatment device 103, for example, it can be disposed at the front end of the treatment device 103 (i.e., the end close to the target object 302). Alternatively, the X-ray source 105 can also be installed 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.

[0072] In some optional 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, in this way, the imaging beam 202 emitted by the X-ray source 105 and the treatment beam 201 emitted by the treatment device 103 can virtually intersect at a certain position (for example, the source-to-original distance SOD is 1 mm) (in fact, the X-ray source 105 and the treatment device 103 do not emit beams at the same time). For example, the position of the virtual intersection can be the treatment center, and the advantage of this is that the tumor position can be monitored while the treatment is being performed. In the case of some tumors that are greatly affected by breathing, the tumor position can be accurately tracked for treatment.

[0073] It can be understood that 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 (that is, a virtual angle is formed between the two), 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.

[0074] In some optional embodiments, the X-ray source 105 and the treatment device 103 may also be configured so 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 may even be virtually parallel, so that there is no need to set an angle between the radiation blocker 104 and the imaging detector 106, thereby facilitating the design and arrangement of the mechanical structure. Figure 3 and Figure 4 As shown, the radiation blocker 104 includes a plate-shaped component, which 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 movement of the main robot 101, thereby ensuring that the imaging center is consistent with the treatment center, and the effect of the inclined installation of the radiation blocker 104 and the imaging detector 106 in the above embodiment can also be achieved.

[0075] As described above, the multi-robot image-guided radiotherapy system of the present invention adopts a dual-robot system, and the main robot 101 and the auxiliary robot 102 each have their own control system. In order to achieve the purpose of treatment and imaging, the two robots need to move in coordination. During the treatment process, the main robot 101 irradiates the treatment position from different angles and at different doses according to the treatment plan, and the auxiliary robot 102 moves with the main robot 101 to ensure that the treatment beam 201 irradiates the approximate center area of ​​the radiation blocker 104 after passing through the treatment site. The absolute position accuracy of the main robot 101 and the auxiliary robot 102 can be, for example, ±0.6mm, which can meet the requirement of treatment accuracy of 1mm.

[0076] In addition, the radiation blocker 104 may be a plate-shaped component, and its area may be designed to be larger so as to leave sufficient accuracy and absorption of scattered rays, so that the position accuracy error of the main robot 101 and the auxiliary robot 102 is within the design margin and can meet the treatment requirements. The radiation blocker 104 may be made of an anti-penetrating radiation material, such as heavy metal materials such as lead.

[0077] like Figure 2aAs shown, when the radiation blocker 104 and the imaging detector 106 are configured as plate-like components, the bottom sides of the two can be connected to the base 107 to achieve synchronous flipping. When the radiation blocker 104 is configured as a cylindrical structure or a disc-shaped structure, a fixing ring can be provided on its circumference, and connected to the base 107 through the fixing ring to achieve the movement of the radiation blocker 104 described in the above various embodiments.

[0078] Example 2

[0079] like Figure 5 As shown, the X-ray source 105 of the imaging device emits an imaging beam 202 and forms a projection 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 (such as a human patient) with the main robot 101 and the auxiliary robot 102 respectively, and projection images at different projection angles can be obtained. The reconstructed 3D image can be obtained by filtering and back-projecting the projection images at different angles.

[0080] In order to reconstruct a 3D image from the projection images, the geometric relationship between the 3D voxel coordinates of each projection image and the 2D pixel position on the imaging detector 106 must be accurately known. The process of obtaining this geometric relationship is geometric calibration, and this geometric relationship is the projection matrix.

[0081] Therefore, geometric relationship is a key factor in determining the quality of CT (computed tomography) or CBCT (cone beam computed tomography) 3D image reconstruction. For the multi-robot image-guided radiotherapy system of the present invention having a main robot 101 and an auxiliary robot 102, the weight of the treatment device 103 carried by the main robot 101 and the radiation blocker 104 carried by the auxiliary robot 102 are particularly heavy. In addition, the X-ray source 105 and the imaging detector 106 of the imaging system are respectively superimposed on the treatment device 103 and the radiation blocker 104, which makes the main robot 101 and the auxiliary robot 102 carry a large load, which will cause their dexterity to be slightly poor; in addition, the main robot 101 and the auxiliary robot 102 are controlled independently, so the accuracy error is the superposition of the errors of the two robots; and the main robot 101 and the auxiliary robot 102 also have path deviations when traversing the circular arc trajectory, such as Figure 7a As shown, of the two concentric circles, the innermost circle is the target path of the imaging detector 106, and the outermost circle is the target path of the X-ray source 105. The darker track is the actual running track of the X-ray source 105, and the track formed by the lighter dots is the actual running track of the imaging detector 106. Figure 7bAs shown, the synchronization control of the main robot 101 and the auxiliary robot 102 is added, but the added synchronization control does 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 the circular orbit in space, and because the deviations are different each time they rotate to the same position, it is difficult to establish the spatial position each time.

[0082] The geometric calibration method of the CBCT imaging system of the present invention aims to obtain a reconstructed image without geometric errors, so as to solve the problem of large errors in the position accuracy and position repeatability of multiple robots.

[0083] Specifically, the CBCT imaging system geometric calibration method of the present invention includes the following operating steps.

[0084] S100: Scanning the geometric calibration phantom 301 at a predetermined position to establish a pre-projection matrix associated with an imaging device of a multi-robot image-guided radiotherapy system.

[0085] As described above, the main robot 101 and the auxiliary robot 102 may deviate from the predetermined track and position during movement, but the deviation is within a certain range, so the obtained pre-projection matrix is ​​also within the deviation range. Using it as the initial value of the iterative algorithm can speed up the calculation process of the iterative algorithm.

[0086] In an optional embodiment, S100 includes the following sub-steps:

[0087] S110: Scan the geometric calibration phantom 301 at a predetermined position to establish a pre-projection matrix associated with an imaging device of the multi-robot image-guided radiotherapy system at each projection angle of the scan.

[0088] More specifically, S110 includes the following sub-steps:

[0089] S111: placing the geometric calibration phantom 301 at the rotation center position of the main robot 101 and the auxiliary robot 102 of the multi-robot image-guided radiotherapy system.

[0090] S112: The main robot 101 and the auxiliary robot 102 rotate around the geometric calibration phantom 301 according to the predetermined imaging path respectively. The X-ray source 105 of the imaging device rotates around the geometric calibration phantom 301 along with the main robot 101 and emits an imaging beam to the geometric calibration phantom 301, thereby obtaining a projection image (u, v) of the geometric calibration phantom on the imaging detector 106 of the imaging device rotating along with the auxiliary robot 102.

[0091] Geometric calibration phantom 301 Figure 8As shown, radiopaque marking points 3011 are arranged thereon. The radiopaque marking points 3011 may be arranged in a spiral manner along the axial direction of the geometric calibration phantom 301, or in other ways, so that the markings 301 are not in the same plane.

[0092] like Figure 6 As shown, the X-ray source 105 and the imaging detector 106 rotate around the rotation center of the target object 302, and the coordinates of the rotation center O are (0,0,0). The spatial coordinates of a point on the target object 302 are (x,y,z), and the projection image of the projection figure of the 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 as shown in formula (1).

[0093]

[0094] Wherein, s is the magnification factor (which is a dimensionless distance weight factor used to match the spatial coordinates (x, y, z) and the projection 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 of real components and can also be called a 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, when the magnification factor is known, as long as the projection matrix is ​​obtained, the spatial coordinates of the target object 302 can be obtained as (x, y, z), thereby completing accurate 3D reconstruction.

[0095] The spatial coordinates of the i-th marking 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, the 3D spatial coordinates of each marker point 3011 are {(x 0 ,y 0 ,z 0 ),(x 1 ,y 1 ,z 1 ),…,(x i ,y i ,z i ),…,(x n ,y n ,z n )} is known on the geometric calibration phantom 301. The projection image corresponding to each marker point 3011 on the imaging detector 106 is {(u 0 ,v 0 ),(u 1,v 1 ),…,(u i ,v i ),…,(u n ,v n )}, the above projection image {(u 0 ,v 0 ),(u 1 ,v 1 ),…,(u i ,v i ),…,(u n ,v n )} can be obtained by detecting the center of the black spot on the projection image. S113: Obtain a pre-projection matrix according to the projection image and the spatial coordinates of each marking point 3011 on the geometric calibration phantom 301.

[0096] According to the above relationship (1), an algebraic matrix relationship between the projection image and the spatial coordinates of each marking point on the geometric calibration phantom 301 can be established, such as formula (2).

[0097]

[0098] Among them, the 3D space coordinates {(x 0 ,y 0 ,z 0 ),(x 1 ,y 1 ,z 1 ),…,(x i ,y i ,z i ),…,(x n ,y n ,z n )} and the projected image {(u 0 ,v 0 ),(u 1 ,v 1 ),…,(u i ,v i ),…,(u n ,v n )} are all known parameters, so the projection matrix can be calculated according to the above relationship (2), and the projection matrix is ​​the pre-projection matrix.

[0099] S200: When performing imaging scanning on the target object 302, the pre-projection matrix is ​​used as the initial value, and an iterative calculation is performed based on the feature points on the real-time projection image obtained in the imaging area by the imaging scan to obtain a corrected projection matrix.

[0100] When the pre-projection matrix is ​​modified to obtain the modified projection matrix, for example, P can be traversed within a certain range. ijEach parameter makes the result on the left side of the equal sign of formula (2) closest to 0. In some optional embodiments, the feature points on the real-time projection image include marking points on the support structure (e.g., treatment bed 111) for supporting the target object 302. The marking points on the support structure supporting the target object 302 are displayed as high-attenuation black points on the real-time projection image.

[0101] Due to the particularity of radiotherapy, in order to facilitate the positioning of the target object 302 (human patient) or anti-collision simulation, a treatment bed 111 with marking points is generally configured. These marking points are equidistantly distributed near the treatment area on the bed board of the treatment bed 111. These marking points are made of high X-ray absorption materials, so they appear as high-attenuation black points on the projection image, which is conducive to feature recognition on the projection image. The marking points fixed on the treatment bed 111 can be the same as the marking points on the geometric calibration phantom 301, that is, the spatial coordinate points of these marking points and their corresponding projection images are all known parameters. Therefore, the projection matrix can be obtained by analyzing the spatial coordinate points of the marking points and their corresponding projection images to obtain the accurate spatial position of the current image, thereby obtaining a reconstructed image with better quality.

[0102] In some optional embodiments, the feature points on the real-time projection image include marking points on the target object 302. The marking points on the target object 302 are displayed as highly attenuated black points on the real-time projection image, which facilitates feature recognition on the projection image.

[0103] Due to the particularity of radiotherapy, CT simulation positioning is usually performed before radiotherapy. During positioning, some marking points are marked on the target object 302 (human patient), and both the forward projection and the lateral projection of these marking points fall near the treatment center. These marking points are also high-attenuation black points on the projection image. Therefore, these feature points can be used to iteratively correct the pre-projection matrix to obtain the accurate spatial position of the current image, thereby obtaining a reconstructed image with better quality.

[0104] In some optional embodiments, the feature points on the real-time projection image include obvious feature positions on the real-time projection image. In such optional embodiments, no marker points are used, but obvious feature points on the projection image (such as bone boundaries) can be used, and the pre-projection matrix can be iteratively corrected by changing the feature points on the close or adjacent projection images to obtain the accurate spatial position of the current image, thereby obtaining a reconstructed image with better quality.

[0105] It should be noted that when performing imaging scan on 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 imaging scan of the target object 302 is performed.

[0106] Because during treatment, in order to prevent the imaging detector 106 from being directly irradiated by the high-energy treatment beam 201 emitted by the treatment device 103 and thus being 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, so that the high-energy treatment beam 201 first passes through the radiation blocker 104, and then reaches the imaging detector 106 after being absorbed by the radiation blocker 104 with a large amount of energy, thereby avoiding damage to the imaging detector 106. Therefore, when performing imaging scanning on the target object 302, it is necessary to move the imaging detector 106 and the radiation blocker 104 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 emits the 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.

[0107] S300: Reconstruct the 3D target object 302 according to the modified projection matrix using a filtered back-projection method.

[0108] According to the corrected projection matrix obtained in the above steps, the projection image is filtered back-projected to obtain the reconstructed 3D target object 302. For example, according to the above formula (2), the 3D spatial coordinates of the target object 302 are unknown parameters, and its projection image and the corrected projection matrix P are both known parameters, so the 3D spatial coordinates of the target object 302 can be calculated according to the above relationship (2), so as to obtain the reconstructed 3D target object 302.

[0109] Furthermore, the multi-robot image-guided radiotherapy system based on the present invention can obtain a reconstructed image without geometric errors through a geometric calibration method. Therefore, the multi-robot image-guided radiotherapy system of the present invention can also change the size of the imaging area. For example, when a real-time projection image is obtained in 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 opening size of the X-ray source 105 of the imaging device can be changed to change the size of the imaging area, so that the main robot 101 and the auxiliary robot 102 of the multi-robot image-guided radiotherapy system can realize movement along any trajectory.

[0110] Because when the opening size of the X-ray source 105 remains unchanged, the attenuation of the dose of the X-ray source 105 is proportional to the square of the distance between the X-ray source 105 and the target object 302, the smaller the imaging distance, the smaller the imaging area. Figure 9a , Figure 9b and Fig.9c As shown, the X-ray source 105 and the imaging detector 106 move simultaneously. The closer the X-ray source 105 is to the target object 302 and the farther the imaging detector 106 is from the target object, the smaller the imaging area is. This allows for more effective use of the dose of the X-ray source 105 and the photosensitive area of ​​the imaging detector 106. Fig.10a , Fig.10b and Fig.10c As shown, by moving the imaging detector 106 away from the target object 302, or moving the X-ray source 105 close to the target object 302, and changing the opening size of the X-ray source 105, the imaging area changes, and the dose of the X-ray source 105 and the photosensitive area of ​​the imaging detector 106 can be more fully utilized.

[0111] Therefore, by reducing the imaging area, lower emission energy can be used to achieve the same image effect. For example, when the human patient is very fat 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.

[0112] like Fig.11a , Fig.11b and Fig.11c As shown, the X-ray source 105 and the imaging detector 106 follow the movement of the main robot 101 and the auxiliary robot 102 respectively, and half-fan imaging can be realized to reconstruct a larger 3D-FOV. Fig.11a As shown, the X-ray source 105 and the imaging detector 106 are not offset, the FOV is 250 mm, and the diameter of the imaging area is D1 (400 mm). Fig.11b As shown, after the imaging detector 106 is offset, its FOV is larger, 250 mm, and the diameter of the imaging area is D2 (310 mm), and D2 is smaller than D1. Fig.11c As shown, after the X-ray source 105 is offset, its FOV is larger, 500 mm, and the diameter of the imaging area is D1 (400 mm).

[0113] like Fig.12a , Figure 12b and Fig.12c As shown, the opening size of the X-ray source 105 can also be gradually reduced to reduce the imaging area.

[0114] The image modes of the multi-robot image-guided radiotherapy system of the present invention include not only CBCT images, but also single image mode and movie mode. Obtaining a projection image at a certain projection angle is the single image mode; while continuously acquiring multiple single images at a constant projection angle is the movie image mode.

[0115] Example 3

[0116] Based on the above-mentioned embodiment 2, the present invention further provides a modified embodiment 3. The difference between embodiment 3 and embodiment 1 is that S120 is used to replace S110, and the similarities between embodiment 2 and embodiment 1 will not be repeated.

[0117] Specifically, S120 is to scan the geometric calibration phantom 301 at a predetermined position multiple times, establish multiple pre-projection matrices related to the imaging device of the multi-robot image-guided radiotherapy system 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 the projection angle.

[0118] S120 includes the following sub-steps:

[0119] S121: placing the geometric calibration phantom 301 at the rotation center position of the main robot 101 and the auxiliary robot 102 of the multi-robot image-guided radiotherapy system.

[0120] S122: The main robot 101 and the auxiliary robot 102 rotate around the geometric calibration phantom 301 according to the predetermined imaging path respectively. The X-ray source 105 of the imaging device rotates to a certain projection angle along with the main robot 101 and emits an imaging beam to the geometric calibration phantom 301, thereby obtaining a projection image (u, v) of the geometric calibration phantom 301 at the projection angle on the imaging detector 106 of the imaging device rotating along with the auxiliary robot 102.

[0121] Geometric calibration phantom 301 Figure 8 As shown, radiopaque marking points 3011 are arranged thereon. The radiopaque marking points 3011 may be arranged in a spiral manner along the axial direction of the geometric calibration phantom 301, or in other ways, so that the markings 301 are not in the same plane.

[0122] like Figure 6 As shown, the X-ray source 105 and the imaging detector 106 rotate around the rotation center of the target object 302, and the coordinates of the rotation center O are (0,0,0). The spatial coordinates of a point on the target object 302 are (x,y,z), and the projection image of the projection figure of the 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 as shown in formula (1).

[0123]

[0124] Wherein, s is the magnification factor (which is a dimensionless distance weight factor used to match the spatial coordinates (x, y, z) and the projection 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 of real components and can also be called a 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, when the magnification factor is known, as long as the projection matrix is ​​obtained, the spatial coordinates of the target object 302 can be obtained as (x, y, z), thereby completing accurate 3D reconstruction.

[0125] The spatial coordinates of the i-th marking 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, the 3D spatial coordinates of each marker point 3011 are {(x 0 ,y 0 ,z 0 ),(x 1 ,y 1 ,z 1 ),…,(x i ,y i ,z i ),…,(x n ,y n ,z n )} is known on the geometric calibration phantom 301. The projection image corresponding to each marker point 3011 on the imaging detector 106 is {(u 0 ,v 0 ),(u 1 ,v 1 ),…,(u i ,v i ),…,(u n ,v n )}, the above projection image {(u 0 ,v 0 ),(u 1 ,v 1 ),…,(u i ,v i ),…,(u n ,v n )} can be obtained by detecting the center of the black spot on the projected image.

[0126] S123: Obtain a pre-projection matrix according to the projection image at the projection angle and the spatial coordinates of each marking point 3011 on the geometric calibration phantom 301.

[0127] According to the above relationship (1), an algebraic matrix relationship between the projection image and the spatial coordinates of each marking point on the geometric calibration phantom 301 can be established, such as formula (2).

[0128]

[0129] Among them, the 3D space coordinates {(x 0 ,y 0 ,z 0 ),(x 1 ,y 1 ,z 1 ),…,(x i ,y i ,z i ),…,(x n ,y n ,z n )} and the projected image {(u 0 ,v 0 ),(u 1 ,v 1 ),…,(u i ,v i ),…,(u n ,v n )} are all known parameters, so the projection matrix can be calculated according to the above relationship (2), and the projection matrix is ​​the pre-projection matrix.

[0130] S124: Repeat S122 and S123 multiple times to obtain multiple pre-projection matrices at the projection angle, and select the pre-projection matrix with the highest probability among the multiple pre-projection matrices as the pre-projection matrix at the projection angle.

[0131] Among them, the pre-projection matrix with the highest probability among multiple pre-projection matrices 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.

[0132] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present 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, characterized in that: include: a treatment device (103) capable of emitting a treatment beam (201); A main robot (101), which is connected to the treatment device (103); an auxiliary 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), wherein the X-ray source (105) is disposed on the treatment device (103), and the imaging detector (106) is connected to the auxiliary robot (102) or the radiation blocker (104); The radiation blocker (104) and the imaging detector (106) are configured such that when the treatment device (103) emits a treatment beam (201), the radiation blocker (104) and the imaging detector (106) move until the radiation blocker (104) faces the treatment device (103) and the imaging detector (106) faces away from the treatment device (103); when the X-ray source (105) emits an imaging beam (202), the radiation blocker (104) and the imaging detector (106) move until the imaging detector (106) faces the X-ray source (105) and the radiation blocker (104) faces away from the X-ray source (105); The imaging detector (106) is arranged on the radiation blocker (104), and an angle is formed between the imaging detector (106) and the radiation blocker (104); the radiation blocker (104) is connected to a base (107), and the base (107) is rotatably connected to a front end (1021) of the auxiliary robot (102); when the base (107) rotates relative to the auxiliary robot (102), the orientation of the radiation blocker (104) can be flipped; The radiation blocker (104) comprises a plate-shaped component, and when the radiation blocker (104) faces the treatment device (103), the plate-shaped component can completely block the imaging detector (106).

2. The multi-robot image-guided radiotherapy system according to claim 1, characterized in that: The treatment device (103) is rotatably connected to the main robot (101), and the X-ray source (105) is arranged on the treatment device (103) and is inclined toward the treatment beam (201) emitted by the treatment device (103).

3. The multi-robot image-guided radiotherapy system according to claim 2, characterized in that: The angle between the radiation blocker (104) and the imaging detector (106) is the same as the virtual angle between the treatment beam (201) and the imaging beam (202).

4. The multi-robot image-guided radiotherapy system according to claim 1, characterized in that: The treatment device (103) is rotatably connected to the main robot (101).

5. The multi-robot image-guided radiotherapy system according to claim 1, characterized in that: The auxiliary robot (102) includes an upper arm (1024) and a lower arm (1022), one end of the upper arm (1024) is connected to a shoulder joint (1025), and the other end is connected to the lower arm (1022) via an elbow joint (1023), the end of the lower arm (1022) is the front end (1021), and the base (107) is rotatably connected to the front end (1021).

6. The multi-robot image-guided radiotherapy system according to claim 5, characterized in that: The base (107) comprises a rotating shaft (1071) and a U-shaped connecting piece (1072) rotatably connected to the rotating shaft (1071), and two ends of the U-shaped connecting piece (1072) are respectively connected to two sides of the front end (1021).

7. The multi-robot image-guided radiotherapy system according to claim 6, characterized in that: The rotating shaft (1071) is capable of rotating along its own axis relative to the U-shaped connecting member (1072) or the front end (1021), or The U-shaped connecting member (1072) can drive the rotating shaft (1071) to rotate relative to the front end (1021), and its rotating axis is perpendicular to the axis of the rotating shaft (1071).

8. The multi-robot image-guided radiotherapy system according to claim 6, characterized in that: The front end (1021) is rotatably connected to the small arm (1022), and the front end (1021) can drive the U-shaped connecting piece (1072) and the rotating shaft (1071) to rotate relative to the small arm (1022) around the axis of the front end (1021).

9. The multi-robot image-guided radiotherapy system according to claim 1, characterized in that: The radiation blocker (104) is made of a radiation-proof material.

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