A proton therapy system CBCT imaging rotating gantry

Abstract

The present application relates to a kind of proton therapy system CBCT imaging rotating gantry, transmission assembly is arranged in the center of rotating gantry assembly and is rigidly connected with it, output gapless rotary driving force;Support wheel assembly is symmetrically arranged in pairs in the both sides of rotating gantry assembly, synchronous realization radial bearing, radial offset limit and power loss locking positioning;Axial limiting wheel assembly is attached to the front and rear end surface of gantry, bidirectional constraint gantry to eliminate axial movement;Flat plate and tube assembly is arranged in the inside of gantry and is synchronously rotated with it to complete cone beam scanning imaging.The present application adopts modular integrated layout, relies on gapless rigid transmission, bidirectional axial limiting and power loss locking structure, can eliminate transmission gap, inhibit rotation offset, prevent gantry axial movement, overcome the defects that existing equipment transmission exists deviation, gantry is prone to movement, lack of safety protection, improve imaging repeatability precision, meet the high-precision positioning requirement of proton radiotherapy.

Description

Technical Field

[0001] The present invention belongs to the technical field of tumor radiotherapy equipment, and more specifically relates to a CBCT imaging rotating gantry for a proton therapy system. Background Art

[0002] Proton radiotherapy relies on the unique physical properties of the Bragg peak to achieve highly concentrated dose in the tumor target area and greatly reduce the damage of rays to the normal tissues surrounding the tumor, making it a core technical means of high-precision tumor radiotherapy at the current stage. In the complete clinical diagnosis and treatment workflow of proton therapy, the on-board CBCT (Cone Beam Computed Tomography) imaging system undertakes key tasks such as patient positioning verification, tumor target localization, anatomical deformation monitoring between fractionated treatments, and proton beam range correction, and is a core supporting imaging device that ensures the accuracy of proton beam irradiation. The core load-bearing component of the CBCT imaging system is the rotating gantry structure, which is used to carry the X-ray tube and the flat panel detector to complete 360° circumferential cone beam scanning imaging. The geometric accuracy, operation stability, structural integration, and scenario adaptability of the gantry directly determine the CBCT imaging quality and tumor localization accuracy, and are the basic prerequisite for ensuring the clinical efficacy of proton therapy.

[0003] With the continuous development of adaptive precision proton radiotherapy technology, clinical diagnosis and treatment scenarios have put forward strict usage requirements for CBCT rotating gantries in terms of miniaturization, high repetitive positioning accuracy, high operation stability, and general adaptability to multiple lesions. At present, the on-board CBCT imaging systems equipped with commercial proton therapy equipment at home and abroad generally adopt the traditional rotating gantry solution of an integral solid annular rotating gantry + external split transmission mechanism + bottom fixed support rollers + fixed imaging components. In this existing solution, a heavy solid steel structural ring is used as the rotating main body, a motor and a reduction box are independently arranged on the outer side of the gantry, and the rotational power is transmitted through flexible transmission structures such as belts and chains; only two sets of support rollers are arranged at the bottom of the gantry, which can only realize radial load bearing without being equipped with a dedicated axial limit structure, and at the same time, the whole machine has no power-loss locking and braking structure; the X-ray tube and the flat panel detector are installed by bolt rigid fixing, without a distance expansion and contraction and angle fine adjustment module, and the whole machine relies on the overall rotation of the solid ring to complete full-angle scanning, so as to realize patient positioning and tumor target localization before proton therapy.

[0004] However, this mainstream traditional CBCT rotating gantry solution exposes many technical defects that cannot adapt to the requirements of high-precision proton radiotherapy in the actual clinical use process, which are specifically reflected in the following aspects:

[0005] First, the overall volume of the gantry is large and the structural integration is low. The traditional gantry adopts a solid integral support structure, matched with external split transmission components, the whole machine occupies a large space in the equipment room, is prone to spatial interference with the patient support system, and has poor flexibility in equipment layout.

[0006] Second, the transmission and braking precision is insufficient, resulting in low positioning repeatability. Traditional solutions rely on flexible components such as belts and chains for transmission, and assembly gaps cannot be eliminated. During gantry rotation, vibration and angular deviation are prone to occur, leading to poor torque output stability. At the same time, conventional support structures do not have power-off locking functions. When the equipment is powered off, in standby mode, or experiences a sudden malfunction, the gantry is prone to slight displacement under external forces. This directly causes deviations in the core imaging geometric parameters of the CBCT system, namely SID (distance from X-ray source to detector) and SAD (distance from X-ray source to rotation axis), ultimately leading to tumor positioning errors and failing to meet the sub-millimeter-level high-precision imaging positioning standards for proton therapy.

[0007] Third, the limiting structure design is imperfect, and long-term operation is prone to axial and radial offset. The existing frame relies solely on bottom support rollers for radial load bearing and does not have a dedicated bidirectional axial limiting structure. Under long-term reciprocating rotation conditions, the frame is prone to problems such as axial movement and radial eccentricity, resulting in a continuous decrease in the alignment accuracy between the X-ray tube and the flat panel detector, an increase in imaging artifacts, a decrease in image resolution, and interference with doctors' identification and registration of tumor target areas and organs at risk.

[0008] Fourth, the imaging components have poor adaptability and insufficient clinical versatility. The X-ray tubes and flat panel detectors of traditional racks are fixed and cannot be adjusted according to the patient's body size, tumor lesion location, and clinical treatment position. This makes it difficult to meet the scanning imaging needs of tumors in different parts of the head and neck, chest and abdomen, and limbs, thus limiting the clinical application scenarios.

[0009] Fifth, the long-term operational stability of the entire machine is poor, and the equipment maintenance cost is high. Traditional rack transmission systems have many redundant parts, which are prone to structural deformation and component wear under long-term continuous rotational load conditions, and the geometric accuracy of the equipment will continue to drift over time. In order to ensure imaging accuracy, frequent shutdowns are required for geometric calibration and component inspection and maintenance, which reduces the clinical turnover efficiency of proton therapy equipment and increases downtime losses and long-term maintenance costs. Summary of the Invention

[0010] In order to address the problems of large size, poor positioning accuracy, easy deviation during operation, weak clinical adaptability, insufficient stability, and high maintenance costs of existing CBCT rotating gantry systems, this invention aims to provide a CBCT imaging rotating gantry for proton therapy systems.

[0011] According to the present invention, a CBCT imaging rotating gantry for proton therapy system includes a transmission assembly, a rotating gantry assembly, a support wheel assembly, an axial limiting wheel assembly, and a plate and X-ray tube assembly. The transmission assembly is located at the center of the rotating gantry assembly and rigidly connected to it, outputting a backlash-free rotational driving force to drive the entire machine to rotate. The rotating gantry assembly is the load-bearing base of the entire machine, and the support wheel assembly, axial limiting wheel assembly, plate and X-ray tube assembly are all assembled on the rotating gantry assembly. The support wheel assemblies are arranged in pairs symmetrically on both sides of the rotating gantry assembly and fit against the outer circular surface of the rotating gantry, simultaneously achieving radial load-bearing, radial offset limitation, and power-off locking positioning. The axial limiting wheel assembly is located below the axial end face of the rotating gantry and presses against the front and rear end faces of the gantry, bidirectionally constraining the gantry to eliminate axial movement. The plate and X-ray tube assemblies are arranged opposite each other and rotate synchronously with the gantry to complete cone-beam scanning imaging. This invention, by setting up five modular and collaboratively arranged components, integrates a radial load-bearing power-off locking structure and a bidirectional axial limiting structure, and configures an imaging component that can rotate synchronously, can simultaneously solve multiple defects of traditional gantry transmission, such as gaps, easy radial displacement of the gantry, axial movement, lack of power-off protection, and fixed installation of imaging devices, and achieves high-precision and high-safety CBCT cone-beam scanning imaging.

[0012] In a preferred embodiment, the transmission assembly consists of a power output component, a speed reducer, a rigid connector, and a transmission shaft, rigidly connected in series along a single axis of rotation. The end of the transmission shaft is fixed to the center of the rotating frame assembly, and the entire transmission chain has no flexible transmission gaps. This invention, by constructing a coaxial rigid series transmission chain, eliminates flexible transmission methods such as belts and chains, thereby eliminating power transmission gaps, preventing vibration and angular deviation during frame rotation, and improving the repeatability of rotational positioning.

[0013] In a preferred embodiment, the rotating frame assembly includes an outer front ring, a radial spoke support structure, a central connecting flange, and an imaging equipment mounting bracket. The outer front ring is located on the axial front side, and the radial spoke support structure is located on the axial rear side of the outer front ring and is fixedly connected to it. The radial spoke support structure has a rear outer ring, with multiple spokes converging radially to the center, where the central connecting flange is fixed to the drive shaft. The imaging equipment mounting bracket is bridging and fixed to the outer front ring and the radial spoke support structure, respectively supporting the flat panel detector and the X-ray tube. This invention employs a double-layer split frame structure with an axial front ring and a rear spoke outer ring, combined with a bridging imaging equipment mounting bracket. This optimizes the frame's weight distribution while ensuring structural load-bearing rigidity, and provides a stable bridging mounting foundation for the imaging components.

[0014] In a preferred embodiment, the radial spoke support structure adopts an oblique truss spoke configuration, with the outer front ring, radial spoke support structure, and central connecting flange integrally fixed to form a unified load-bearing base. This invention, through the oblique truss spoke and integrated load-bearing base design, can uniformly transmit rotational torque, reduce the overall weight of the frame, decrease the load on the transmission system, and alleviate structural deformation and geometric accuracy drift problems under long-term reciprocating rotation conditions.

[0015] In a preferred embodiment, a through-hole channel is provided in the middle of the outer ring front body, allowing the patient support system and the patient to extend into the channel to complete the scan. By providing a through-hole channel in the middle of the outer ring front body, this invention avoids spatial interference between the gantry and the patient support system, improving the flexibility of clinical equipment placement.

[0016] In a preferred embodiment, each set of support wheel assemblies integrates a locking component. The locking component is normally released and locks the support wheels in the event of a power outage. The paired support wheels work together to support the outer circumference of the outer ring. By integrating a power-off locking component into the support wheel assemblies and arranging them symmetrically in pairs, this invention simultaneously achieves radially balanced load-bearing of the frame and provides locking protection against unexpected conditions, stably maintaining the imaging geometric reference for each scan and avoiding the safety risks caused by accidental frame rotation.

[0017] In a preferred embodiment, the axial limiting wheel assembly is equipped with a pre-tightening adjustment component and a pair of limiting rollers. The pair of limiting rollers respectively abut against the front and rear axial end faces of the outer ring. The pre-tightening adjustment component continuously provides clamping force to achieve bidirectional limiting. This invention, through the bidirectional clamping of the frame end faces by the pair of rollers and the pre-tightening adjustment component, can continuously constrain the axial movement of the frame, maintain long-term alignment between the X-ray tube and the flat panel detector, reduce imaging artifacts, and ensure image resolution.

[0018] In a preferred embodiment, the limiting roller rolls synchronously with the rotation of the outer ring front body, without generating additional rotational resistance. This invention employs a driven rolling limiting roller structure, which, while achieving axial constraint, avoids increasing the frame's rotational resistance and does not interfere with normal scanning rotational motion.

[0019] In a preferred embodiment, the flat plate and X-ray tube assembly consists of a flat plate assembly and an X-ray tube assembly, which are mounted opposite each other on a rotating gantry assembly. The flat plate assembly is equipped with a linear telescopic drive structure and an angle adjustment structure; the X-ray tube assembly is equipped with an attitude adjustment support structure. This invention, by configuring independent adjustment structures for the flat plate assembly and the X-ray tube assembly respectively, enables independent adjustment of the imaging device's mounting distance and attitude, adapting to diverse clinical scanning conditions.

[0020] In a preferred embodiment, the flat panel assembly and the X-ray tube assembly can be simultaneously adjusted in terms of installation distance and posture to match standardized imaging geometric parameters. This invention, through the coordinated adjustment of the flat panel assembly and the X-ray tube assembly, can flexibly match the imaging geometric parameters required in clinical practice, adapting to the positioning and scanning needs of patients with all body types and different lesion sites, thus broadening the applicable scenarios of the equipment.

[0021] This invention employs a modular integrated layout scheme, combined with a backlash-free rigid transmission structure, a lightweight double-spoke frame, a support structure that combines radial load-bearing and power-off locking functions, and a bidirectional pre-tightened axial limiting structure. It also incorporates a flat panel and X-ray tube imaging assembly capable of adjusting installation distance and orientation. This effectively eliminates transmission backlash, suppresses rotational jitter and angular deviation, evenly supports the rotating frame, provides locking protection under fault conditions, constrains axial movement of the frame, and maintains stable alignment of the imaging devices. Furthermore, it flexibly adapts to different clinical scanning conditions, overcoming the shortcomings of existing solid frames such as excessive weight, long-term accuracy drift, positioning deviation due to flexible transmission, easy frame displacement, lack of safety protection, and fixed imaging device installation methods. This improves the long-term operational stability and imaging repeatability accuracy of the entire machine, ensuring CBCT imaging quality and meeting the high-precision positioning requirements of proton radiotherapy. Attached Figure Description

[0022] Figure 1 This is a general structural diagram of a CBCT imaging rotating gantry for a proton therapy system according to the present invention;

[0023] Figure 2 This is a schematic diagram of the independent structure of the transmission component of the present invention;

[0024] Figure 3 This is a schematic diagram showing the disassembled assembly of the internal components of the transmission assembly of the present invention;

[0025] Figure 4 This is a schematic diagram of the individual structure of the rotating frame assembly of the present invention;

[0026] Figure 5 This is a schematic diagram of the connection and assembly of the rotating frame assembly and the drive shaft of the present invention;

[0027] Figure 6 This is a schematic diagram of the independent structure of a single support wheel assembly of the present invention;

[0028] Figure 7 This is a schematic diagram showing the assembly positions of the two sets of support wheel assemblies and the rotating frame of the present invention;

[0029] Figure 8 This is a schematic diagram of the independent structure of a single axial limiting wheel assembly of the present invention;

[0030] Figure 9 This is a schematic diagram showing the overall assembly position of the axial limiting wheel assembly and the rotating frame of the present invention;

[0031] Figure 10 This is a schematic diagram of the independent structure of the flat panel component of the present invention;

[0032] Figure 11 This is a schematic diagram of the independent structure of the X-ray tube assembly of the present invention. Detailed Implementation

[0033] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0034] like Figure 1 As shown, the present invention discloses a CBCT imaging rotating gantry 1 for proton therapy system. The whole adopts a modular integrated collaborative layout structure. The whole machine mainly includes five functional modules: transmission component 11, rotating gantry component 12, support wheel component 13, axial limiting wheel component 14, and flat plate and X-ray tube component 15.

[0035] The transmission component 11 is located at the center of the rotating frame component 12 and is rigidly fixed to the rotating frame component 12. As the core of the whole machine, it is used to output a smooth and gapless rotational driving force to drive the frame to rotate in a circular motion.

[0036] The rotating frame assembly 12 is the load-bearing base of the whole machine, and all other components are directly or indirectly assembled on the rotating frame assembly 12.

[0037] The support wheel assembly 13 is symmetrically arranged on the left and right sides of the rotating frame assembly 12, and fits the outer circular surface of the rotating frame assembly 12. It is used for radial bearing, limiting the radial displacement of the frame and realizing power-off locking braking.

[0038] The axial limiting wheel assembly 14 is mounted below the axial end face of the rotating frame assembly 12 and is pressed and fitted against the front and rear end faces of the rotating frame assembly 12 to constrain the frame in both directions and prevent axial movement.

[0039] The flat plate and the X-ray tube assembly 15 are arranged in a cross-facing manner, and their mounting bases are fixed to the circular part of the rotating frame assembly 12. The imaging main body extends outwards from each other and serves as the imaging execution component, which can rotate 360° synchronously with the frame to complete the cone beam scanning.

[0040] This invention adopts a modular integrated layout, with each module being independently assembled and disassembled without interfering with each other, which greatly reduces the difficulty of equipment assembly and maintenance, while also reducing the space occupied by the whole machine.

[0041] like Figures 2-3 As shown, the transmission assembly 11 is the core component for the power drive of the whole machine, including a servo motor 111, a reducer 112, a rigid coupling 113, and a transmission shaft 114. The four components are rigidly assembled coaxially along the same axis, and the entire transmission chain has no flexible transmission gap.

[0042] The servo motor 111 serves as the power input source, enabling precise control of the output speed and rotation angle to meet the angle control requirements of high-precision imaging scanning. The output end of the servo motor 111 is fixedly connected to the input port of the reducer 112. The reducer 112 can precisely reduce the output speed of the servo motor 111 while amplifying the output torque, enabling a small-volume motor to drive a heavy frame. Compared with the existing external split belt / chain flexible transmission technology, the integrated reduction structure of this invention is smaller in size and has more stable torque output.

[0043] The output end of the reducer 112 is coaxially and securely connected to the transmission shaft 114 via a rigid coupling 113. The rigid coupling 113 ensures that the transmission shaft 114 and the output end of the reducer 112 remain without gap and rotate completely synchronously. There will be no shaking or angular deviation during the rotation of the frame, which ensures the rotational positioning accuracy from the power source and solves the defect of imaging positioning error caused by transmission gap in the existing technology.

[0044] The end of the drive shaft 114 away from the rigid coupling 113 is rigidly connected to the center of the rotating frame assembly 12, directly transmitting the backlash-free and highly stable rotational power to the rotating frame assembly 12, ensuring uniform angle reference throughout the imaging scanning process.

[0045] like Figures 4-5 As shown, the rotating frame assembly 12 includes an outer front ring 121, a radial spoke support structure 122, a central connecting flange 123, and an imaging equipment mounting bracket 124.

[0046] The outer ring front body 121 forms the annular main body on the axial front side of the rotating frame assembly 12, and has a hollow annular structure. The outer ring front body 121 has a continuous outer circumferential cylindrical surface and a front axial end face. The outer circumferential cylindrical surface is used to fit with the support wheel assembly 13 to achieve radial bearing. The rear end face of the outer ring front body 121 is fixedly connected to the radial spoke support structure 122. A large-sized hollow channel is formed in the center of the outer ring front body 121, which allows the patient support system and the patient to extend into the ring for scanning imaging. Compared with the existing solid annular frame, the hollow channel can effectively avoid spatial interference between beds and improve the flexibility of equipment layout and clinical use.

[0047] A radial spoke support structure 122 is arranged on the axial rear side of the outer ring front body 121. The radial spoke support structure 122 includes a rear outer ring and multiple support spokes, which are arranged radially along the circumference. The outer ends of the support spokes are fixed to the inner side of the rear outer ring, and the inner ends of the support spokes converge towards the center of the frame. The front outer edge of the radial spoke support structure 122 is integrally and tightly connected to the rear end face of the outer ring front body 121. Compared with the existing thick solid steel structure ring, this split double-layer ring + spoke hollow structure reduces the rotational load of the whole machine, reduces the load on the transmission system, alleviates the problems of structural deformation and geometric accuracy drift under long-term reciprocating rotation conditions, reduces the frequency of downtime calibration, and reduces maintenance costs.

[0048] The central connecting flange 123 is located at the center of the radial spoke support structure 122. The central connecting flange 123 has a central shaft hole and an assembly positioning hole. The central connecting flange 123 is used to rigidly connect with the drive shaft 114 in the transmission assembly 11. Power can be evenly transmitted to the outer ring front ring 121 through the central connecting flange 123 and the radial spoke support structure 122, driving the entire rotating frame assembly 12 to rotate synchronously and smoothly, avoiding slippage gaps during power transmission, and ensuring the repeatability and positioning accuracy of the frame rotation angle.

[0049] The imaging equipment mounting bracket 124 is simultaneously fixedly assembled on the inner wall of the outer ring front body 121 and the radial spoke support structure 122. The imaging equipment mounting bracket 124 includes two types of mounting bases. One type is a truss-type support bracket that extends axially outward. The truss relies on multiple diagonal members to form a stable triangular support structure, and a flat mounting platform is set at the end of the truss for mounting the flat panel detector. The other type is a fixed rectangular mounting base, arranged on the inner side below the outer ring front body 121, for mounting the X-ray tube. The truss-type support bracket can extend the mounting platform outward, providing a mounting base for the adjustable assembly structure of the flat panel assembly and the X-ray tube assembly, facilitating flexible adjustment of the imaging device spacing and achieving adaptive adjustment of the imaging geometric distance.

[0050] The outer front ring 121, the radial spoke support structure 122, and the central connecting flange 123 are fixedly connected to form an integrated rotating load-bearing base. The imaging equipment mounting bracket 124 is bridging and fixed to the outer front ring 121 and the radial spoke support structure 122, enabling the entire frame to achieve 360° synchronous rotation. During the operation of the equipment, the rotational torque output by the drive shaft is transmitted to the radial spoke support structure 122 via the central connecting flange 123, thereby driving the outer front ring 121, the imaging equipment mounting bracket 124, and the plate and X-ray tube mounted on the bracket to move synchronously in a circular motion, completing the CBCT cone beam projection data acquisition.

[0051] like Figures 6-7As shown, the support wheel assembly 13 includes a support base 131, a bearing end cap 132, a support roller 133, and a power-off electromagnetic brake 134.

[0052] The support base 131 is an integral load-bearing bracket, adopting a box-type welded truss structure. A flange mounting plate is installed at the bottom, with through holes for fixing the support base 131 to the machine's foundation platform. The support base 131 extends upwards to form symmetrically arranged support arms, with triangular reinforcing ribs between the support arms to enhance structural rigidity. Compared to a simple plate-type bracket, the box-type reinforced structure can withstand the continuous radial load applied by the rotating frame assembly 12, suppressing structural deformation caused by long-term operation and maintaining stable roller alignment accuracy.

[0053] The top of the support arm has a bearing mounting position, and the bearing is assembled inside the bearing mounting position; the support shaft passes through the inner ring of the bearing and can rotate freely around its own axis; the support shaft serves as a common mounting shaft for the support roller 133 and the de-energized electromagnetic brake 134, achieving coaxial integrated arrangement; the bearing end cover 132 is installed on the outer end of the bearing position of the support arm, pressing the outer ring of the bearing, and is used to axially limit and protect the bearing from dust, restricting the axial movement of the bearing and the support shaft.

[0054] The support roller 133 is fixedly mounted in the middle of the support shaft; the outer circular surface of the support roller 133 is used to tangentially fit with the outer cylindrical surface of the outer ring 121 of the rotating frame assembly 12. Multiple sets of support rollers 133 cooperate with each other to form radial support for the rotating frame assembly 12, limit the radial runout and radial eccentricity of the rotating frame assembly 12, and ensure the roundness of the frame rotation movement.

[0055] The de-energized electromagnetic brake 134 is coaxially mounted on the end of the support shaft and rotates synchronously with the support roller 133. The de-energized electromagnetic brake 134 adopts a working mode of energized release and de-energized locking. When the equipment is powered on and scanning is being carried out, the de-energized electromagnetic brake 134 releases the brake, and the support roller 133 can passively rotate with the outer ring surface of the rotating frame assembly 12 with low running resistance and without interfering with the normal rotation of the frame. When the equipment stops, experiences an unexpected power outage, or a malfunction occurs, the de-energized electromagnetic brake 134 immediately locks the support shaft, causing the support roller 133 to stop rotating, and locking the entire rotating frame assembly 12 by the friction between the roller and the outer ring front ring 121.

[0056] Compared to existing support rollers without a braking structure, this invention integrates a power-off electromagnetic brake 134, which can prevent the gantry from shifting slightly under external forces during power outages or malfunctions, stably maintaining the imaging geometric reference parameters and improving the repeatability of tumor localization; at the same time, it can prevent the gantry from accidentally rotating and colliding with the equipment or injuring the patient, thus improving the safety of the equipment in clinical use.

[0057] Combination Figure 7 As shown, the whole machine is symmetrically arranged with two sets of support wheel assemblies 13. The two sets of support wheel assemblies 13 are symmetrically arranged on both sides below the rotating frame assembly 12. The two sets of support rollers 133 simultaneously contact the outer cylindrical surface of the outer ring front ring 121, and work together to complete the radial bearing and braking locking functions, so that the rotating frame assembly 12 is subjected to balanced force and avoids the wear caused by unilateral force.

[0058] like Figure 8 As shown, the axial limiting wheel assembly 14 includes a limiting support base 141, a mounting plate 142, a pre-tightening adjustment mechanism 143, and a limiting roller 144. The axial limiting wheel assembly 14 is an independent modular unit that can be disassembled and assembled and the gap adjusted independently, which facilitates factory debugging and subsequent on-site precision maintenance.

[0059] The limiting support base 141 is a box-shaped welded load-bearing bracket with a mounting base plate at the bottom. The base plate has through holes for fixing the axial limiting wheel assembly 14 to the machine's foundation platform. Triangular reinforcing ribs are arranged around the limiting support base 141 to improve the overall structural bending stiffness. It can continuously withstand the axial force transmitted by the limiting roller 144 and is not prone to deformation under long-term working conditions, thus ensuring the stability of the limiting position.

[0060] The mounting plate 142 is horizontally fixed at the top of the limiting support base 141. The mounting plate 142 has multiple sets of assembly holes for arranging the pre-tightening adjustment mechanism 143 and the limiting rollers 144. In this embodiment, the limiting rollers 144 are arranged in pairs on the mounting plate 142, respectively abutting against the front and rear axial end faces of the outer ring 121 of the rotating frame assembly 12.

[0061] The pre-tightening adjustment mechanism 143 is assembled between the mounting plate 142 and the limiting roller 144. The pre-tightening adjustment mechanism 143 can adjust the extension height of the limiting roller 144, so that the limiting roller 144 continuously presses the axial end face of the outer ring front ring 121 with a preset pressure to achieve elastic fit. At the same time, the pre-tightening adjustment mechanism 143 can compensate for the machining error of the parts and the assembly gap, ensuring that the rollers on both sides can always fit tightly against the end face of the frame.

[0062] The limiting roller 144 is rotatably mounted on the upper end of the pre-tightening adjustment mechanism 143; the wheel surface of the limiting roller 144 is in contact with the axial end face of the outer ring front ring 121. When the rotating frame assembly 12 undergoes circumferential rotation, the limiting roller 144 can passively follow the end face of the frame to roll, without creating additional resistance to the normal rotation of the frame.

[0063] Combination Figure 9As shown, the entire machine is equipped with at least one set of axial limiting wheel assemblies 14, which are arranged below the rotating frame assembly 12. Two sets of limiting rollers 144 clamp the outer ring front ring 121 from both the front and rear sides of the axial direction. The bidirectional clamping constraint can completely limit the axial movement and slight front-rear displacement of the rotating frame assembly 12, and continuously ensure that the X-ray tube and flat panel detector mounted on the imaging equipment mounting bracket 124 on the rotating frame assembly 12 remain in a centered state for a long time.

[0064] Compared to existing technologies that only have radial support and lack axial restraint, this invention eliminates axial displacement of the frame through a bidirectional clamping restraint roller structure, avoids drift in imaging geometry parameters caused by forward and backward movement, reduces CBCT image artifacts and resolution degradation, and stably ensures the accuracy of tumor target area positioning, meeting the sub-millimeter precision imaging requirements of proton radiotherapy.

[0065] Back Figure 1 The plate and tube assembly 15 includes a plate assembly 151 and a tube assembly 152. The plate assembly 151 and the tube assembly 152 are arranged opposite to each other and are integrally connected and assembled on the outer ring front ring 121 and the radial spoke support structure 122 of the rotating frame assembly 12, and can achieve 360° synchronous rotation with the rotating frame assembly 12.

[0066] like Figure 10 As shown, the flat panel assembly 151 includes a flat panel mounting base 1511, a linear drive module 1512, a detector carrying platform 1513, a flat panel detector fixing clamp 1514, a flat panel detector 1515, and an angle fine-tuning mechanism.

[0067] The flat panel mounting base 1511 serves as the mounting reference for the flat panel assembly 151, and is used for overall hoisting and fixing onto the imaging equipment mounting bracket 124 of the rotating frame assembly 12. The detector carrier platform 1513 is the carrier base, used to support the flat panel detector fixing clamp 1514, the flat panel detector 1515, and the angle fine-tuning mechanism. The flat panel detector fixing clamp 1514 is mounted on the detector carrier platform 1513 and is used to clamp and fix the flat panel detector 1515. The linear drive module 1512 is assembled between the flat panel mounting base 1511 and the detector carrier platform 1513. The linear drive module 1512 can drive the detector carrier platform 1513, the flat panel detector fixing clamp 1514, and the flat panel detector 1515 to achieve linear telescopic movement. The angle fine-tuning mechanism (not shown in the figure) consists of an adjusting workpiece and an adjusting screw, and is assembled on the detector carrier platform 1513, the flat panel detector fixing clamp 1514, and the flat panel detector 1515.

[0068] By cooperating with the linear drive module 1512 and the angle fine-tuning mechanism, the extension distance and installation tilt angle of the flat panel detector can be flexibly adjusted. Compared with the fixed detector installation structure of the prior art, this invention can adaptively adjust the imaging geometry parameters according to clinical needs, adapt to the scanning requirements of patients of different body types and different lesion sites, ensure the accuracy of CBCT imaging, and meet the high-precision positioning requirements of proton radiotherapy.

[0069] like Figure 11 As shown, the X-ray tube assembly 152 includes an X-ray tube mounting base 1521, an adjustable support truss 1522, and an X-ray tube body 1523.

[0070] The X-ray tube mounting base 1521 serves as the mounting reference plate for the X-ray tube assembly 152, and is used to fix it onto the imaging equipment mounting bracket 124 of the rotating gantry assembly 12. One end of the adjustable support truss 1522 is connected to the X-ray tube mounting base 1521, and the upper part of the adjustable support truss 1522 supports and mounts the X-ray tube body 1523. The adjustable support truss 1522 can finely adjust the installation position and tilt angle of the X-ray tube body 1523. The X-ray tube body 1523 serves as a radiation emitting unit, used to generate a conical X-ray beam that is emitted towards the flat panel detector.

[0071] Before clinical scanning, the X-ray tube body 1523 can be adjusted synchronously using the telescopic and angle adjustment functions of the flat panel assembly 151 to precisely match the imaging geometric parameters required for clinical use. Compared with the existing technology where the X-ray tube is completely fixed and cannot be adjusted, this invention can flexibly adjust the imaging conditions according to the patient's body shape and lesion location, adapting to the positioning and scanning needs of tumors in different parts of the head, neck, chest, abdomen, and limbs, stably ensuring CBCT imaging quality, and meeting the sub-millimeter-level high-precision positioning requirements of proton radiotherapy.

[0072] The complete workflow of the present invention is briefly described below.

[0073] In clinical use, the patient lies on the patient support system and is placed in the center of the hollow ring of the rotating gantry assembly 12. Based on the patient's body size and tumor location, the detector carrier platform 1513 automatically extends and retracts via the linear drive module 1512 of the flat panel assembly 151. The angle fine-tuning mechanism and adjustable support truss 1522 are pre-determined in position and angle during equipment installation, maintaining a fixed position throughout the clinical scanning process. The optimal imaging geometry parameters are matched by the extension and retraction stroke of the flat panel detector 1515. After parameter adjustment, the servo motor 111 outputs a precise rotational speed, which is then reduced by a reducer 1. The 12-speed reduction and torque increase system, along with the rigid coupling 113, transmits torque seamlessly to the drive shaft 114, driving the rotating frame assembly 12, the flat plate, and the X-ray tube assembly 15 to rotate synchronously at a constant speed of 360°, continuously completing cone-beam scanning imaging. After scanning is completed, the equipment stops, and the de-energized electromagnetic brake 134 of the support wheel assembly 13 immediately locks the support shaft and support roller 133, locking the rotating frame assembly 12 to prevent the frame from shifting. If a power outage or malfunction occurs during equipment operation, the de-energized electromagnetic brake 134 will lock synchronously to avoid the safety risks of collisions or patient injuries caused by accidental rotation of the frame.

[0074] The technical advantages of this invention are briefly described below.

[0075] 1) The double-layer hollow spoke lightweight rotating frame, composed of an outer front ring body 121 and a radial spoke support structure 122, and rigidly connected to the central connecting flange 123 and the drive shaft 114, solves the defects of traditional solid ring frames, such as large size, high weight, and easy deformation and geometric accuracy drift during long-term operation. The whole machine has a compact structure, can avoid spatial interference with the patient support system, has stronger long-term operation stability, and significantly reduces the frequency and cost of operation and maintenance.

[0076] 2) The servo motor 111, reducer 112, and rigid coupling 113 form a backlash-free transmission system, eliminating assembly gaps caused by flexible transmissions such as belts and chains, preventing frame rotation vibration and angular offset problems, achieving sub-millimeter repeatability positioning accuracy, and meeting the high-precision imaging positioning requirements of proton therapy.

[0077] 3) The left and right support wheel assemblies 13 integrate power failure electromagnetic brakes 134, which simultaneously realize the dual functions of radial load limit and power failure locking of the rotating frame assembly 12, stabilize and unify the geometric reference of each scanning imaging, and avoid equipment damage and personnel safety hazards caused by accidental rotation of the frame.

[0078] 4) The axial limiting wheel assembly 14 relies on the pre-tightening adjustment mechanism 143 to drive the limiting roller 144 to press the axial end face of the outer ring front ring 121 in both directions, and to constrain the axial movement of the rotating frame assembly 12 in both directions, so as to ensure that the X-ray tube body 1523 and the flat panel detector are accurately aligned for a long time, reduce imaging artifacts, improve image resolution, and facilitate doctors to accurately identify tumor target areas and organs at risk.

[0079] 5) The flat panel assembly 151 has adaptive adjustment capabilities for telescopic and pitch angles. Combined with the adjustable support truss 1522 of the X-ray tube assembly 152, it can adapt to the radiotherapy imaging needs of patients of all body types and different parts, improve the clinical versatility of the equipment, and broaden the applicable scenarios of proton therapy CBCT equipment.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A CBCT imaging rotating gantry for proton therapy system, characterized in that, It includes a transmission assembly (11), a rotating frame assembly (12), a support wheel assembly (13), an axial limiting wheel assembly (14), and a plate and tube assembly (15). The transmission component (11) is located at the center of the rotating frame component (12) and is rigidly connected to the rotating frame component (12), and outputs a gapless rotational driving force to drive the whole machine to rotate. The rotating frame assembly (12) is the load-bearing base of the whole machine. The support wheel assembly (13), the axial limiting wheel assembly (14), and the plate and tube assembly (15) are all assembled on the rotating frame assembly (12). The support wheel assemblies (13) are arranged symmetrically in pairs on both sides of the rotating frame assembly (12) and fit against the outer circular surface of the rotating frame, so as to simultaneously realize radial bearing, radial offset limitation and power failure locking positioning. The axial limiting wheel assembly (14) is located below the axial end face of the rotating frame and presses against the front and rear end faces of the frame, thus constraining the frame in both directions to eliminate axial movement. The flat plate and the X-ray tube assembly (15) are arranged in a cross-shaped manner, and the cone beam scanning imaging is completed synchronously with the frame.

2. The CBCT imaging rotating gantry of the proton therapy system according to claim 1, characterized in that, The transmission assembly (11) consists of a power output component, a speed reducer, a rigid connector, and a transmission shaft (114) arranged in a rigid series along a single rotation axis. The end of the transmission shaft (114) is fixed to the center of the rotating frame assembly (12), and the entire transmission chain has no flexible transmission gap.

3. The CBCT imaging rotating gantry of the proton therapy system according to claim 1, characterized in that, The rotating frame assembly (12) includes an outer ring front body (121), a radial spoke support structure (122), a central connecting flange (123), and an imaging equipment mounting bracket (124). The outer ring front body (121) is located on the axial front side, and the radial spoke support structure (122) is located on the axial rear side of the outer ring front body (121) and is fixedly connected to the outer ring front body (121). The radial spoke support structure (122) has its own rear outer ring, and multiple spokes converge radially to the center. The central connecting flange (123) at the center is fixed to the drive shaft (114). The imaging equipment mounting bracket (124) is bridging and fixed on the outer ring front body (121) and the radial spoke support structure (122), respectively supporting the flat panel detector and the X-ray tube.

4. The CBCT imaging rotating gantry of the proton therapy system according to claim 3, characterized in that, The radial spoke support structure (122) adopts an oblique truss spoke configuration. The outer ring front body (121), the radial spoke support structure (122), and the central connecting flange (123) are integrally fixed to form an overall load-bearing base.

5. The CBCT imaging rotating gantry of the proton therapy system according to claim 3, characterized in that, A through-hole channel is provided in the middle of the outer ring anterior body (121), which allows the patient support system and the patient to extend into the channel to complete the scan.

6. The CBCT imaging rotating gantry of the proton therapy system according to claim 1, characterized in that, Each set of support wheel assemblies (13) integrates a locking component. The locking component is normally released and locks the support wheel under power failure conditions. The pair of support wheels jointly fit against the outer circumferential surface of the outer ring front body (121) to jointly bear the load.

7. The CBCT imaging rotating gantry of the proton therapy system according to claim 1, characterized in that, The axial limiting wheel assembly (14) is equipped with a pre-tightening adjustment component and a pair of limiting rollers. The pair of limiting rollers abut against the front and rear axial end faces of the outer ring front ring body (121) respectively. The pre-tightening adjustment component continuously provides clamping force to achieve bidirectional limiting.

8. The CBCT imaging rotating gantry of the proton therapy system according to claim 7, characterized in that, The limiting roller rotates synchronously with the outer ring front ring (121) without generating additional rotational resistance.

9. The CBCT imaging rotating gantry of the proton therapy system according to claim 1, characterized in that, The plate and tube assembly (15) is divided into a plate assembly (151) and a tube assembly (152), which are mounted on the rotating frame assembly (12) in opposite directions. The plate assembly (151) is equipped with a linear telescopic drive structure and an angle adjustment structure. The tube assembly (152) is equipped with an attitude adjustment support structure.

10. The CBCT imaging rotating gantry of the proton therapy system according to claim 9, characterized in that, The flat panel assembly (151) and the X-ray tube assembly (152) can be simultaneously adjusted in terms of installation distance and installation posture to match standardized imaging geometry parameters.

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