WO2020082654A1

WO2020082654A1 - Composite double-rotation frame accelerator-based non-coplanar radiotherapy apparatus

Info

Publication number: WO2020082654A1
Application number: PCT/CN2019/076320
Authority: WO
Inventors: 唐志全; 李志平; 张伟; 侯氢; 徐庆丰; 李涛; 钟仁明; 黄绍进; 文艳秋
Original assignee: 四川大学华西医院
Priority date: 2018-10-23
Filing date: 2019-02-27
Publication date: 2020-04-30
Also published as: CN109224320A

Abstract

Disclosed is a composite double-rotation frame accelerator-based non-coplanar radiotherapy apparatus, comprising: a main frame rotating along the xz plane, and a secondary frame rotatably connected to the main frame. The secondary frame rotates along the yz plane; the main frame carries two CBCT subsystems; the two CBCT subsystems are arranged orthogonally; and the secondary frame carries an accelerator radiation component and an EPID flat panel detector. The present invention can achieve multi-beam stereotactic directional radiation therapy, has a simple structure, high isocenter accuracy and low cost, and can realize high-efficiency operation, and safe treatment.

Description

Accelerator non-coplanar radiotherapy device based on compound dual rotating gantry

Technical field

The invention relates to a medical device, in particular to an accelerator non-coplanar radiotherapy device based on a composite dual rotating gantry.

Background technique

So far, X (γ) -ray radiation therapy technology has three major achievements, which are multi-beam focused irradiation technology based on non-coplanar irradiation, and intensity-modulated radiation therapy implemented by a multileaf collimator (MLC) ( Intensity Modulated Radiation Therapy (IMRT) and image-guided radiotherapy (IGRT) based on KV grade X-ray cone beam CT (Cone Beam CT, CBCT).

Practice has proved that non-coplanar multi-beam irradiation can actively avoid dangerous organs near the target area or the ray path, reduce the body's exposure volume and reduce its total dose, thus increasing the target dose of the tumor. Because the rotating frame of the traditional accelerator can only rotate coplanar in a plane, non-coplanar irradiation is achieved by isocentric rotation of the treatment bed on the horizontal plane; due to the clear space of the collimator end face of the radiation head from the isocenter It can only achieve about 400mm. After the treatment bed rotates, it will cause the risk of collision between the radiation head and the treatment bed or the patient. In addition, in most cases, the rotation range of the rotating gantry is narrow, causing many blind spots, so the traditional accelerator is still It is more difficult to irradiate lesions such as lung cancer, liver cancer and pituitary tumors, and it can also cause serious side effects such as radiation pneumonia. In addition, the additional installed CBCT further limits the rotatable range of the treatment bed and the technical efficiency of the equipment. Third, bed rotation during treatment increases the risk of target movement.

The products that use the accelerator X radiation source to achieve non-coplanar multi-beam irradiation in the true sense are the CyberKnife manufactured by Accuray in the United States and the Vero manufactured by Mitsubishi Heavy Industries, Ltd. in Japan.

The accelerator radiation head of the wave knife is carried by a six-degree-of-freedom robot with a nominal source wheelbase (Source to Axial Distance, SAD) of SAD = 800 mm, which is irradiated by a non-coplanar multi-point method. The shortcomings of this product are: first, the kV-level X-ray image is a static X-ray image, there is no CBCT function, and there is no MV-level X-ray electronic image verification device (Electronic, Portal, Imaging, Device, EPID); Third, the use of multi-joint robots to carry accelerators increases the difficulty of robotic arm path planning in the reverse planning process, thereby increasing the development cost of the radiotherapy planning system (Radiation Therapy Treatment Planning, TPS) and thus resulting in product prices in the About 8 million US dollars.

Vero uses an aperture structure, and the O-ring frame rotates ± 180 ° under the drive of a crank arm to realize the 360 ° coplanar rotation function of the traditional accelerator frame. On this basis, the ring frame is added on the horizontal plane. , ± 60 ° rotation function with respect to the x-axis of the treatment bed to achieve non-coplanar irradiation, SAD = 1000 mm; 30 pairs of MLC blades with a fineness of 5 mm form a 150 mm × 150 mm irradiation field in the isocenter plane. Due to the need to form an angle of ± 60 ° between the ring-shaped frame and the treatment bed without interference, the aperture of the ring-shaped frame carrying the radiation head of the accelerator is bound to be large, resulting in a slight deflection of the radiation head at certain angles. This kind of deflection uses a universal head mechanism that can rotate ± 2.5 ° in the direction of the ring of the ring frame and the axis direction perpendicular to the plane of the ring frame to aim at the isocenter, so the product structure is complicated , Which in turn leads to higher manufacturing costs and ultimately higher selling prices. In addition, tapered hole collimators are not provided.

Summary of the invention

The invention aims to provide an accelerator non-coplanar radiotherapy device based on a composite dual rotating gantry, which can realize multi-beam stereotactic radiotherapy and stereotactic radiosurgery, with simple structure, high isocenter accuracy, low cost and efficient operation 1. Safe treatment.

To achieve the above objectives, the present invention is implemented using the following technical solutions:

The accelerator non-coplanar radiotherapy device based on the composite dual rotating gantry of the present invention includes a main frame rotating along the xz plane and a secondary frame rotatingly connected to the main frame The rack carries two sets of CBCT subsystems, the two sets of CBCT subsystems are arranged orthogonally, and the secondary rack carries accelerator radiation heads and EPID flat panel detectors.

Further, it also includes a vertical frame, the main frame is a circular disc-shaped main frame, the secondary frame is a double-ring rectangular secondary frame, the circular disc-shaped main frame is rotatably connected to the vertical frame, and the double-loop rectangular The two rings of the secondary rack and the two crutches. The two rings are directly opposite and set vertically. The ring-shaped disk-shaped main frame is connected to the two secondary rack support frames. The two rings are respectively connected to the two secondary racks. The support frame rotates and connects, the two secondary frame support frames are fixedly connected with the ring-shaped disc-shaped main frame, the rotation plane of the two rings is perpendicular to the rotation plane of the ring-shaped disc-shaped main frame, and the upper ends of the two rings are connected to the two The lower end of each cantilever, the accelerator radiating head is connected between the upper ends of the two cantilevers, the EPID flat panel detector is directly opposite to the accelerator radiating head, the EPID flat panel detector is connected to the double ring rectangular sub-frame, the EPID flat panel detector is below The bottom of the ring.

Preferably, the two sets of CBCT subsystems include a first CBCT tube, a first CBCT flat panel detector, a second CBCT tube, and a second CBCT flat panel detector between two arms and two rings. The first CBCT tube, the first CBCT flat-panel detector, the second CBCT flat-tube detector, and the second CBCT flat-panel detector are all connected to a circular disk-shaped main frame, and the first CBCT flat-panel detector is directly opposite to the first CBCT tube , The second CBCT flat panel detector is directly opposite to the second CBCT tube; the first CBCT flat panel detector and the second CBCT flat panel detector are arranged at an oblique angle, and the first CBCT tube and the second CBCT tube Located above the first CBCT flat panel detector and the second CBCT flat panel detector.

Preferably, the first CBCT bulb and the second CBCT bulb are higher than the center of the circle, and the first CBCT flat panel detector and the second CBCT flat detector are lower than the center of the circle.

Preferably, the first CBCT tube and the second CBCT tube are respectively connected to the circular disc-shaped main frame through the first tube tube arm and the second tube tube arm, and the first tube tube arm and the second The tube arm is stepped.

Further, the double-ring rectangular sub-frame is provided with a movable counterweight, the first CBCT flat panel detector and the second CBCT flat panel detector are respectively connected to a support arm through a single-joint rotating mechanical arm, and the support arm is connected to a ring disk Main frame.

Preferably, the appearance of the radiation head of the accelerator is a flat cylindrical shape, and the radiation head of the accelerator is provided with a tapered hole collimator.

Preferably, the EPID flat panel detector is installed at the top of the support frame, and both ends of the support frame are respectively connected to the bottoms of the two rings through L plates, and the movable counterweight is movably connected to the support frame. The support frame includes A rectangular frame, which is located at the bottom of the support frame, at least one side of the rectangular frame is open, and the movable weight is located in the rectangular frame.

Further, it also includes an accelerator control system, the movable counterweight is controlled by the accelerator control system, and the accelerator control system solidifies the position of the movable counterweight in the combined state of the CBCT subsystem, the accelerator radiation head and the EPID flat panel detector .

Preferably, the ring is connected to the subframe support frame through a ring-shaped rotating bearing.

Specifically, in the above solution, the carrier frame of the accelerator radiating head is not a single-axis coplanar rotating frame of a traditional accelerator, but a composite dual-axis rotating frame composed of a primary and secondary frame, which realizes coplanar and Non-coplanar compound double rotation; one rotation of the compound biaxial rotating frame is a circular disk-shaped main frame rotating ± 180 ° around the y axis in the xz plane to achieve 360 ° coplanar rotation; the compound two The re-rotation is a double-ring rectangular secondary rack rotating ± 45 ° around the x axis in the yz plane to achieve non-coplanar multi-beam irradiation; the secondary rack rotation plane and the main rack rotation plane are perpendicular to each other, and the secondary rack rotation axis x axis is The y-axis of the rotation axis of the main frame is located at the isocenter horizontal plane and is orthogonal to each other, the intersection point is the isocenter point (according to the convention of accelerator equipment, the isocenter point is the origin of the three-dimensional coordinates).

The composite double rotating frame is composed of a double ring rectangular secondary frame through a secondary frame support frame, a secondary frame support frame and a circular disc-shaped main frame. The center of mass of the circular disc-shaped main frame is located on the y-axis. The ring-shaped disk-shaped main frame and the vertical frame are connected in a ring-shaped rotation, the rotation axis is the y-axis, two sets of orthogonal CBCT are symmetrically installed on the ring-shaped disk-shaped main frame on both sides of the yz plane, and two sub-frame support frames Installed symmetrically and parallelly on the outside of the CBCT system symmetrically about the xy plane and the yz plane. Prior to the compound connection of the secondary racks, the center of mass of the ring-shaped disk-shaped main frame is located on the yz plane. The counterweight places the center of mass on the y-axis; the secondary frame is connected to the secondary frame support frame and the secondary frame support frame as ring-shaped rotating bearings through the secondary frame rotation support arm and the secondary frame rotation support arm respectively, and the rotation axis For the x-axis, the center of gravity of all components on the secondary frame is symmetrical about the xz plane and the yz plane. When the secondary frame rotates, the center of mass is placed at the isocenter through proper weighting.

The compound rotary connection between the primary and secondary frames is connected by a ring-shaped rotary bearing symmetrical about the yz plane. Due to the high precision of the rotary bearing, the compound rotary connection is automatically symmetrical about the xy plane and the xz plane; On the rotating main arm of the disc-shaped main frame and the secondary frame, positioning pins are respectively provided for the secondary frame support frame and the accelerator radiation head support frame, the EPID and the counterweight support frame, which can reduce or even eliminate the secondary frame at the user site, etc. Center debugging; the circular compound rotary connection does not affect the operator when the patient's lesion is located at the isocenter on both sides of the treatment bed to observe the coincidence of the laser lines placed on the walls on both sides and the patient's body surface marks.

The appearance of the accelerator radiating head 4 is a flat cylindrical shape, so that at the edge limit position of the secondary frame ± 45 °, in the entire 360 ° rotation range of the main frame, a 800 mm diameter cylinder is wrapped around the y axis to avoid any collision. Safe net space; all microwave devices are integrated inside the radiation head, including magnetron, flexible waveguide, directional coupler, four-terminal circulator, phase detector, water load and cooling water pipe; the center of gravity inside the accelerator radiation head is optimized Is symmetrical about the xz plane and the yz plane.

The sum of the tube support arms is stepped. The step is located on the ± 45 ° plane of one or two quadrants on the ring-shaped disk-shaped main frame. The lower step is close to the isocenter side and is vertically installed on the ring-shaped disk-shaped main frame. When the secondary frame rotates to + 45 ° in 3 directions, the tube support arm will not interfere with the accelerator head support frame; the upper step is away from the isocenter, and the tube is installed on the mounting end surface of the upper step to ensure the focus of the X-ray tube 1000mm from the isocenter, that is, the focal axis distance of the tube (Focal to Axial Distance) FAD = 1000mm, at this time, the distance between the focal points of the two tubes is about 1400mm; the tube end adjustment mechanism and filter are also installed on the upper step Components.

The support arm of the flat panel detector is a linear arm, the linear arm is vertically installed on a circular disc-shaped main frame, the end is a single-joint rotating mechanical arm, and has a mounting end surface parallel to the linear arm, the flat plate bracket is installed on the mounting end surface, the flat plate The detector is installed on the flat panel support; the two flat panel detectors can be rotated 180 ° towards the axial direction of the flat panel arm respectively, even when the flat panel is rotating, it is still symmetrical about the yz plane; when the CBCT system is used for image guidance, the flat panel The detector is located close to the isocenter, the detector element is facing the focus of the tube. In the CBCT not in use or standby state, the flat panel detector is located away from the isocenter, and the back side of the tablet is covered with copper to ensure high energy during accelerator treatment X-ray scattered rays have minimal damage to the detector elements, extending the life of flat panel detectors. The flat panel detector is about 540mm away from the isocenter, that is, the source image distance SID (Source to Image Distance) is about 1540mm. The larger the SID, the clearer the image.

The EPID flat panel detector can move up and down in the direction of the ray beam, and it is raised when used without being lowered; a thin lead plate which can be opened and closed symmetrically in parallel along the y direction is provided on the top of the flat panel, and the flat panel is separated when the flat panel is raised and used When the flat plate is lowered, the cover plate is closed when not in use, so that the high-energy X-rays passing through the human body can minimize the damage to the detector element, and the symmetrical characteristics of the flat panel detector about the xz plane are not changed.

The counterweight includes a fixed position part and an adjustable position part, which is symmetrical about the xz plane and the yz plane. It has sufficient resolution to move up and down along the beam direction. The accelerator control system can recognize all states and automatically control the counterweight to move to all positions. Position required; the state of the accelerator radiation head is 2 kinds, only MLC or conical hole collimator is used at the same time; the state of the EPID flat panel detector is 2 kinds, it is not used when it is lowered or raised; the state of the CBCT flat panel detector is 2 Species, used facing the tube or not facing the tube; the secondary frame rotation angle position is accurate to 1 °, there are 91 positions; the composite frame rotation has 2 states, the main frame rotation or the sub frame rotation; accelerator control The system pre-calculates and stores the positions of the counterweights in all combined states, and automatically drives the counterweights in place.

So far, it has been applied to accelerator radiation therapy devices in medical clinics. No product has the ability to rotate the radiation head around the x axis, so all TPSs that are available do not have the irradiation method of the sub-frame rotation; the above solution The characteristic of TPS in is that in addition to the function of rotating the conventional frame around the y-axis, it also has the function of rotating the secondary frame around the x-axis; it has the function of reconstruction of the slice image under any non-coplanar illumination mode, and the direction of any beam Digitally reconstructed image (Digitally Reconstructed Radiograph, DRR) function, beam direction view (BEV) function of any ray beam direction.

The beneficial effects of the present invention are as follows:

(1) The rotary connection of the main and secondary frames are all circular ring-shaped rotary connections, which is convenient for the use of rotary bearings in manufacturing, and the balance requirements of the rotary bearings only require the center of mass to be located at any point on the axis of rotation, with a high axial And radial load capacity, it only needs to overcome a small friction force to easily drive when balancing, and the rotating bearing itself has extremely high precision of micron level, which is easy to ensure that the accuracy of the isocenter of the accelerator treatment device is maintained at sub-millimeter level the above.

(2) The compound dual rotating frame with a simple structure has high market value because of its advantages of high precision and low manufacturing cost.

(3) The combined rotating irradiation mode of the main and secondary racks is essentially the main frame rotating irradiation after determining the angle of the secondary rack, whether it is the reverse planning process of the TPS or the real treatment process, it reflects the simple process and efficient operation specialty.

(4) The rotational movement of the treatment bed is eliminated, and the 800mm diameter safe rotation net space is eliminated, which eliminates the risk of patient displacement caused by the rotation movement of the treatment bed and the corresponding risk of collision of the radiation head during the treatment process, which improves the treatment The safety is also convenient for the use of treatment aids such as respiratory gating.

(5) Since the non-coplanar stereotactic radiotherapy and non-coplanar stereotactic radiosurgery irradiation methods are realized in a true sense, it can significantly improve the radiotherapy efficacy of traditional accelerators such as lung cancer, liver cancer and pituitary tumors, which are difficult to irradiate lesions. Reduce or even prevent the occurrence of radiation pneumonitis in the radiotherapy of lung cancer.

BRIEF DESCRIPTION

Figure 1 is a schematic diagram of the main structure of the present invention;

2 is a schematic front view of the layout of the primary and secondary racks in the first embodiment;

3 is a schematic diagram of the size of the right side view of the radiation head in the first embodiment;

4 is a schematic front view of the structure layout of the primary and secondary racks in the second embodiment;

5 is a schematic diagram of the size of the right side view of the radiation head in the second embodiment;

In the picture: 1: vertical frame; 2: ring-shaped disk-shaped main frame; 2-1: secondary frame support frame 1; 2-2: secondary frame support frame 2; 2-3: CBCT1 tube and arm ; 2-4: CBCT1 flat panel detector and support arm; 2-5: CBCT2 tube and support arm; 2-6: CBCT2 flat panel detector and support arm; 3: secondary frame; 3-1: secondary Rotating arm 1 of the frame; 3-2: Rotating arm 2 of the secondary frame; 3-3: Support frame of the radiation head of the accelerator; 3-4: Support frame of the EPID flat panel detector and counterweight; 3-5: Counterweight ; 4: accelerator radiation head; 4-1: EPID flat panel detector and bracket; 4-2: acceleration tube; 4-3: primary collimator; 4-4: leveling filter; 4-5: ionization chamber: 4 -6: Spotlight reflector; 4-7: y direction tungsten door; 4-8: x direction tungsten door; 4-9: x direction MLC; 4-10: tapered hole collimator and mounting bracket; 5: treatment bed; 5-1: treatment bed surface; 5-2: treatment end weight.

detailed description

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the drawings.

Example one

The accelerator non-coplanar radiotherapy device based on the compound dual rotating gantry according to the present invention includes: a stand 1, a circular disk-shaped main frame 2, a CBCT1 tube and a support arm 2-3, and a CBCT1 flat panel detector And support arm 2-4, CBCT2 tube and support arm 2-5, CBCT2 flat panel detector and support arm 2-6, secondary rack support frame 2-1, secondary rack support frame 2-2, double ring rectangle Subframe 3 (including subframe rotating arm 3-1, subframe rotating arm 3-2, accelerator radiation head support frame 3-3, EPID flat panel detector and counterweight support frame 3-4), Accelerator radiation head 4, EPID flat panel detector and bracket 4-1, counterweight 3-5, tapered hole collimator 4-10, treatment bed 5, and TPS (not shown in the figure).

The rotating connection of the main frame and the secondary frame adopts rotary bearings, the bearing outer casing is fastened on the fixed frame, and the inner sleeve fastens a ring-shaped short tube, and the ring-shaped short tube is fastened on the rotating part; for the main frame, fixed The frame is a fixed stand 1 with reinforcing ribs fixed on the embedded base, and the rotating part is a circular disc-shaped main frame 2; for the secondary frame 3, the fixed frames are the secondary frame support frames 2-1 and 2-2 , The rotating part is two rotating arms 3-1 and 3-2. The ring-shaped short tube has a ring of teeth on the outer ring, which is used as a tooth for the transmission of the tooth chain, and the metal chain is hung on the teeth for transmission. The drive motor uses a bidirectional rotating DC servo motor with a reduction gear and a braking device. The drive motor of the main frame is horizontally installed on the bottom plate of the stand 1 behind the square hole in the lower right corner of the figure. The motor shaft extends from the square hole. The disc gear is installed on the gear, the chain is sleeved on the gear, and the motor rotates in two directions to drive the main frame to rotate in two directions; a tensioning wheel is also installed at an appropriate position on the stand. The driving mode of the rotating arms of the sub-frame is the same, and the two rotating arms 3-1 and 3-2 are synchronously driven by a double motor. The motor is installed on the ring-shaped disk-shaped main frame 2, and the shafts of the two motors are respectively left and right. The right side is perpendicular to the planes of the subframe support frames 2-1 and 2-2, and the gears on the motor shaft are parallel to the plane of the subframe support frames. The square holes on the secondary rack support frames 2-1 and 2-2 are used to facilitate the passage of various cables, cooling water pipes, and sulfur hexafluoride gas pipes. In the manufacturing process, the rotary bearing is permanently assembled, that is, the ring-shaped disc-shaped main frame 2 is pre-assembled on the stand 1 in the factory, and packaged and shipped as an integral part to the user site; the rotating arm of the secondary frame 3-1 and 3-2 are assembled to the secondary rack support frames 2-1 and 2-2, respectively, and are packaged and shipped as integral components to the user site.

According to the convention of accelerator equipment, when the ray direction is vertically down along the z-axis, it is the 0 ° position of the co-rotating main frame. The rotation angle of the main frame is defined as clockwise rotation of 0 ° ~ + 180 °, and counterclockwise rotation of 0 ° ～ -180 °, the main frame can be rotated from -180 ° to 360 ° to + 180 °, and vice versa; in the present invention, when the ray direction is vertically down along the z-axis, it is 0 ° of the secondary frame For the position, the rotation angle of the secondary rack when rotating in the direction of the main frame is positive, the rotation angle of the secondary rack when rotating in the direction away from the main frame is negative, and the rotation range of the secondary frame is ± 45 °.

This embodiment uses a conventional accelerator with a source axis distance SAD = 1000mm, and ensures that when the secondary frame rotates to the limit position of ± 45 °, the vertical distance of the lower edge of the accelerator radiation head from the y-axis is greater than or equal to 400mm, that is The primary and secondary racks are in any position, and there is a cylindrical safe clear space with a diameter of 800mm along the y-axis.

2 and 3, at this time, the installation positions of the CBCT tube support arms 2-3 and 2-5, the installation positions of the CBCT detector plate support arms 2-4 and 2-6, and the secondary rack are formed The installation position of the supporting frames 2-1 and 2-2 and the length of the contact surface installed on the main frame, the length of the rotating arms 3-1 and 3-2 of the secondary frame, the height of the isocenter, and the departure of the isocenter Factors such as the distance of the ring-shaped disk-shaped main frame 2, the height of the accelerator radiating head 4, the width of the radiating head 4, the shape of the radiating head 4, and the length of the acceleration tube.

The constraint size calculated initially in this embodiment is as follows, but is not limited to a more optimal size.

The diameter of the circular disk-shaped main frame 2 is 2400mm, and the diameter of the circle cut off at the center is 800mm, which is exactly equal to the diameter of the safe cylindrical clear space. Cables, cooling water pipes and sulfur hexafluoride gas pipes can be passed from the side of the fixed stand to the main frame through the appropriate position of the inner edge of the main frame ring, and then arranged to their respective target positions. The height of the isocenter is 1350mm, and the isocenter is 1050mm away from the main frame.

The CBCT system is located on the ± 45 ° line of both sides of the main frame and is orthogonal to each other. The vertical distance of the center of the installation position of the tube arm is about 600mm from the isocenter, and the center of the installation position of the flat panel detector arm is the isocenter The vertical distance is about 635mm. The tube support arm is stepped. The step is located on the ± 45 ° plane of the two quadrants on the ring-shaped disk-shaped main frame 2. The lower step is close to the isocenter side, and is vertically installed on the ring-shaped disk-shaped main frame 2 for secondary operation. When the frame 3 rotates to + 45 °, the tube arms 2-3 and 2-5 will not interfere with the accelerator head support frame 3-3; the upper step is far from the isocenter, and the tube is installed on the mounting end surface of the upper step On the top, ensure that the focal distance of the X-ray tube is 1000mm, that is, the focal length of the tube (Focal to Axial Distance) FAD = 1000mm, at this time, the distance between the focus of the two tubes is about 1400mm; the ball is also installed on the upper step Tube end face adjustment mechanism and filter assembly.

The flat detector arms 2-4 and 2-6 are linear arms. The linear arms are installed vertically on the ring-shaped disk-shaped main frame 2. The end is a single-joint rotating mechanical arm and has a mounting end surface parallel to the linear arm. On the mounting end surface, the flat panel detector is mounted on the flat panel bracket; the two flat panel detectors can be rotated 180 ° about the axial direction of the flat panel arm respectively, even when the flat panel is rotating, it is still symmetrical about the yz plane; in the CBCT system During image guidance, the flat panel detector is located close to the isocenter, and the detector element faces the focus of the tube. In the CBCT not in use or standby state, the flat panel detector is located away from the isocenter, and the back side of the flat panel is covered with copper. Ensure that the scattered rays of high-energy X-rays during the accelerator treatment will minimize the damage to the detector elements and extend the service life of the flat panel detector. The flat panel detector is about 540mm away from the isocenter, that is, the source image distance SID (Source to Image Distance) is about 1540mm. The larger the SID, the clearer the image.

The secondary rack support brackets 2-1 and 2-2 are installed vertically and in parallel and are symmetrical from top to bottom, left and right. Their mounting end faces on the main rack 2 are longer than 1000mm, and the distance between them is about 1600mm; the secondary rack rotation support arm 3-1 and 3-2 is installed on the outer side of the support frame of the secondary rack, so that various cables, cooling water pipes and sulfur hexafluoride gas pipes are arranged around the rotating arm of the secondary rack.

The secondary frame rotating arms 3-1 and 3-2 are about 1800mm long, and the ends of the supporting frames 3-3 and 3-4 are truncated so that when each angle is rotated to the bottom, there is still about 50mm from the ground At the same time, the top of the accelerator radiation head 4 is also truncated for the same purpose.

EPID flat panel detector 4-1 can move up and down along the direction of the ray beam, and it is raised when used without being lowered; a thin lead plate that can be opened and closed in parallel along the y direction is provided on the top of the flat panel, and the flat panel is separated when the flat panel is raised and used When the flat plate is lowered, the cover plate is closed when not in use, so that the high-energy X-rays passing through the human body can minimize the damage to the detector element, and the symmetrical characteristics of the flat panel detector about the yz plane are not changed.

The counterweight 3-5 includes a fixed part and a part that can move up and down in the direction of the beam. The balance mechanism is: the counterweight 3-5 itself is symmetrical about the xz plane and the yz plane. The moving part has sufficient resolution to move up and down in the direction of the beam Adjustment; when the double-ring rectangular secondary frame 3 rotates, no matter the EPID flat panel detector is in the raised or lowered position, the counterweight is moved to place the center of mass of the secondary frame 3 at the isocenter; the ring-shaped disk-shaped main frame 2 rotates When the center of gravity on both sides of the yz plane is always symmetrical, the accelerator control system pre-calculates and stores the position of the counterweight 3-5 in all combined states, and automatically drives the counterweight 3-5 in place, placing the center of mass of the composite rack at y On the shaft.

The height of the radiation head of the accelerator is about 650mm, and the length in the x direction is 600mm. This size can be increased to about 700mm according to the specific design needs. At this time, when the height of all collimating components is 80mm, the center line of the radiation head is from top to bottom. Installed in order: acceleration tube 4-2, 80mm high primary collimator 4-3, ionization chamber 4-5, 80mm high y direction tungsten gate (secondary collimator) 4-7, 80mm high x direction tungsten Doors 4-8, 80mm high x direction MLC 4-9. In the actual design, the height of the tungsten gate 4-8 in the x direction only needs 20mm, and the remaining 60mm space can meet the needs of selective installation of the leveling filter and the reflector of the spotlight. At the same time, it can also appropriately reduce the overall quality of the accelerator radiation head . The tungsten gate is a double-focusing method, that is, the motion track of the tungsten gate is ring-shaped, and the end face of the tungsten gate is parallel to the ray beam in different irradiation fields. In addition, all microwave devices are integrated inside the radiation head, including magnetron, flexible waveguide, directional coupler, four-terminal circulator, phase detector, water load and cooling water tube; the center of gravity inside the accelerator radiation head 4 Optimized to be symmetrical about the xz plane and the yz plane. In this embodiment, the length of the accelerating tube is limited to less than 300 mm, so a C-band accelerating tube is used to provide 6MeV single energy X-radiation radiation therapy. In order to prevent the deflection of the radiation head of the accelerator, the support frame has reinforcement ribs and the main frame of the support frame is integrally manufactured with the mounting frame in the radiation head and is located on the plane of the center of mass of the radiation head.

The width of the accelerator radiating head 4 in the y direction is about 360 mm, and the top and bottom are both symmetrically truncated at 100 mm, and the top width after the truncation is 200 mm and the bottom width is 140 mm. The size of the irradiation field in the y direction is determined by the opening and closing of the tungsten gate in the y direction and the number of MLC blades moving in the x direction; the upper edge of the MLC is about 250 mm from the radiation source, so the magnification ratio is 4, which is the MLC blade on the isocenter plane The width is 4 times its physical width; MLC blades with a physical width of 1.5mm are used, and the width on the isocenter plane is 6mm; 50 pairs of MLC blades are installed with a physical width of 75mm, and 300mm irradiation can be obtained on the isocenter plane wild. The size of the irradiation field in the x direction is determined by the opening and closing degree of the tungsten gate in the x direction and the length of the MLC blade that can move freely in the x direction; although the length of the radiation head in the x direction is 600mm to 700mm, but the The centerline requirement limits the size of the irradiation field in the x direction to 300 mm. MLC is a single focus mode, that is, the MLC motion track is linear, and the end surface of the MLC blade is circular. In this embodiment, an irradiation field with a size of 300 mm × 300 mm can be realized on the isocenter plane, and the fineness of the MLC blade is 6 mm.

The width of the treatment bed surface 5-1 is 520mm, and the maximum range of left and right movement is ± 140mm. When the thickness of the human body is 100mm, the treatment bed drops 100mm, and the left and right movement range is ± 120mm; the minimum height of the treatment bed from the ground is about 700mm , A special ladder is arranged on one side of the treatment bed body to facilitate the patient to get on and off the treatment bed. Since the rotation requirement of the treatment bed is eliminated, the technical efficiency of the equipment will not be affected.

Since the rotation axis of the secondary frame is the x-axis over the isocenter, the secondary frame occupies the space near the isocenter on both sides of the treatment bed. In order to facilitate the operator to position the patient's lesion to the isocenter, in the treatment room An additional set of laser lights is placed on the side wall and roof, and the planes of the three laser lights are translated toward the bed of the treatment bed to avoid the position occupied by the secondary rack, forming a virtual isocenter O ₁ = (x ₁ , y ₁ , z ₁ ), its positional relationship with the true isocenter O = (0,0,0) is xx ₁ = 0, yy ₁ = constant, zz ₁ = constant; design an automatic button in place next to the treatment bed, complete After the virtual isocentric position is set, just press the auto-in-position button. The treatment bed automatically moves to the real isocenter by ascending and the panel is moved forward. The operator stands outside the rotating ring of the secondary frame, and observes and confirms the positioning again. The position of the laser line coincides with the marking line on the patient's body surface. This method is also used for the placement of the equivalent water phantom during machine dose calibration and the placement of the two-dimensional water tank during machine data acquisition.

Example 2

As shown in Figure 1, Figure 4 and Figure 5, in this embodiment, SAD = 1200mm, the length of the acceleration tube is still 300mm, and the width of the radiation head in the y direction is still 360mm, which is different from the first embodiment. The truncated part of the bottom 100mm is replaced by a detachable tapered hole collimator 4-10; at this time, the height of the accelerator radiation head is 750mm, the isocenter height is 1550mm, and the isocenter is 1200mm away from the main frame.

The lengths of the mounting end surfaces of the secondary rack support frames 2-1 and 2-2 on the main frame 2 are greater than 1100mm, and the mutual distance is still 1600mm; the length of the secondary rack rotation arms 3-1 and 3-2 is increased to approximately 2000mm. The mounting positions and methods of all the arms of the CBCT system on the ring-shaped disk-shaped main frame 2 are the same as those in the first embodiment.

When the height of all collimation components is 80mm, the inner center line of the radiation head is installed in order from top to bottom: acceleration tube 4-2, primary collimator 4-3, leveling filter 4-4, ionization chamber 4- 5. Spotlight reflector 4-6, y direction tungsten door 4-7, x direction tungsten door 4-8, x direction MLC 4-9. The lower end of the radiating head is installed with a mounting bracket for a tapered hole collimator with a height of 30 mm, and a detachable tapered hole collimator with a height of 100 mm 4-10 is mounted on the bracket. As in the first embodiment, in actual design, the height of the tungsten gate in the x direction is 20 mm.

The distance between the upper edge of the MLC blade and the radiation source is about 360mm, and the magnification ratio is about 3.333. If the MLC blade with a physical width of 1.5mm is used, the projection width of the MLC blade on the isocenter plane is 5mm, and 50 MLC blades are in the y-axis direction, etc. The radiation field in the center plane is 250 mm. Therefore, in this embodiment, an irradiation field with a size of 250 mm × 250 mm can be realized on the isocenter plane, and the fineness of the MLC blade is 5 mm. The distance of the cone hole collimator 4-10 from the radiation source is about 480mm, and the magnification ratio is 2.5. When the diameter of the cone hole is 1.2mm along the diameter, the diameter can be obtained in the isocenter plane

Of the circular irradiation field, so the size of the tapered hole collimator in the isocenter plane uses the diameter

The same size is used to carry out non-coplanar stereotactic radiosurgery.

The implementation process of the present invention shows that changing the cylindrical radiating head used in the conventional accelerator into a rectangular flat radiating head also makes the present invention more beautiful in appearance. The above implementation process also shows that: with the target window at the end of the acceleration tube as the boundary, the accelerator radiation head can be divided into upper and lower parts; the length of the upper part of the acceleration tube restricts the isocentric height, and the length of the acceleration tube can be selected by changing the isocentric height If the isocenter height is changed to 1400mm in the first embodiment, an acceleration tube with a length of 350mm, that is, an S-band acceleration tube can be used, and the S-band acceleration tube is the most mature and inexpensive acceleration tube, which makes the acceleration tube The choice is more flexible; if the X-band acceleration tube with a length of 250mm is used in the second embodiment, the isocenter height can be reduced to 1500mm; according to the law of inverse square of the intensity of the radiation field, the intensity of the isocenter plane irradiation field is SAD when SAD = 1200mm = 1.44 at 1000mm, which is 69.44%, the dose rate of modern accelerators can be very high, and the total dose of each treatment of the present invention must be distributed to tens or even hundreds of non-coplanar irradiation fields, after SAD is extended It does not affect the technical efficiency of the accelerator, and the large source wheelbase results in a large source skin distance, which is beneficial to reduce the surface dose of human skin. Example 2 is a preferred embodiment of the present invention, benefiting from a wide non-coplanar coverage of 2π spherical angle along the body trunk direction, non-coplanar stereotactic rotational intensity-modulated radiation therapy based on 5mm fine MLC is expected to be significantly improved Lung cancer, liver cancer and other body parts are more difficult to irradiate the focus of radiotherapy, and effectively reduce or eliminate the probability of radiation pneumonitis; based on diameter

The non-coplanar stereotactic rotational intensity-modulated radiosurgery treatment of the series of tapered hole collimators is expected to significantly improve the radiotherapy effect of pituitary tumors and other heads that are difficult to irradiate lesions.

Of course, there can be many other embodiments of the present invention. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes And modifications shall fall within the scope of protection of the claims appended to the present invention.

Claims

An accelerator non-coplanar radiation therapy device based on a composite dual rotating gantry is characterized by comprising a main frame rotating along the xz plane, and a secondary frame rotatably connected to the main frame, the secondary frame rotating along the yz plane, The main frame carries two sets of CBCT subsystems, the two sets of CBCT subsystems are arranged orthogonally, and the secondary frame carries an accelerator radiation head and an EPID flat panel detector.
An accelerator non-coplanar radiotherapy device based on a composite dual rotating gantry is characterized in that it also includes a stand, the main frame is a circular disk-shaped main frame, and the secondary frame is a double-loop rectangular secondary frame, The ring-shaped disk-shaped main frame is rotatably connected to the vertical frame, the double ring-shaped rectangular subframe has two rings and two crutches, the two rings are directly opposite and vertically set, and the ring-shaped disk-shaped main frame is connected to two A secondary rack support frame, two rings are rotatably connected to the two secondary rack support frames, the two secondary rack support frames are fixedly connected to the ring-shaped disk-shaped main frame, the rotation plane of the two rings and the ring The rotation plane of the disk-shaped main frame is vertical, the upper ends of the two circular rings are respectively connected to the lower ends of the two cantilever arms, and the accelerator radiation heads are connected between the upper ends of the two cantilever arms. The EPID flat panel detector is directly opposite to the accelerator radiation head. The EPID flat panel detector is connected to the double ring rectangular sub-frame, and the EPID flat panel detector is lower than the bottom of the ring.
The accelerator non-coplanar radiotherapy device based on a compound dual rotating gantry according to claim 2, characterized in that the two sets of CBCT subsystems include a first CBCT tube located between two crutches and two rings , The first CBCT flat panel detector, the second CBCT tube, the second CBCT flat panel detector, the first CBCT tube, the first CBCT flat panel detector, the second CBCT tube, the second CBCT flat panel detector are all connected A ring-shaped disk-shaped main frame, the first CBCT flat panel detector is directly opposite to the first CBCT tube, the second CBCT flat panel detector is directly opposite to the second CBCT tube; the first CBCT flat panel detector, The second CBCT flat panel detector is relatively inclined, and the first CBCT bulb and the second CBCT bulb are located above the first CBCT flat panel detector and the second CBCT flat panel detector.
The accelerator non-coplanar radiotherapy device based on a composite dual rotating gantry according to claim 3, wherein the first CBCT tube and the second CBCT tube are higher than the center of the ring, and the first The CBCT flat panel detector and the second CBCT flat panel detector are lower than the center of the circle.
The accelerator non-coplanar radiotherapy device based on a compound dual rotating gantry according to claim 3 or 4, wherein the first CBCT bulb and the second CBCT bulb are passed through the first bulb support arm, The second bulb support arm is connected to the circular disk-shaped main frame, and the first bulb support arm and the second bulb support arm are stepped.
The accelerator non-coplanar radiotherapy device based on a compound dual rotating gantry according to claim 5, characterized in that: the double ring rectangular secondary gantry is provided with a movable counterweight, the first CBCT flat panel detector, the second The CBCT flat panel detectors are respectively connected with support arms through a single-joint rotating mechanical arm, and the support arms are connected with a circular disk-shaped main frame.
The accelerator non-coplanar radiation therapy device based on a compound dual rotating gantry according to claim 6, wherein the appearance of the accelerator radiation head is a flat column shape, and the accelerator radiation head is externally provided with a tapered hole collimator.
The accelerator non-coplanar radiotherapy device based on a compound dual rotating gantry according to claim 6 or 7, wherein the EPID flat panel detector is installed at the top of the support frame, and the two ends of the support frame pass through The L plate is connected to the bottoms of the two rings. The movable counterweight is movably connected to the support frame. The support frame includes a rectangular frame. The rectangular frame is located at the bottom of the support frame. At least one side of the rectangular frame is open. The movable frame The counterweight is located inside the rectangular frame.
The accelerator non-coplanar radiotherapy apparatus based on a compound dual rotating gantry according to claim 8, further comprising an accelerator control system, the movable counterweight is controlled by an accelerator control system, and the accelerator control system The position of the movable counterweight in the combined state of the CBCT subsystem, accelerator radiation head and EPID flat panel detector is cured.
An accelerator non-coplanar radiation therapy device based on a composite dual rotating gantry according to claim 2, wherein the ring is connected to the secondary gantry support frame through a ring-shaped rotating bearing.