WO2021087681A1

WO2021087681A1 - Cone-beam-based helical volumetric modulated radiation therapy device and image system

Info

Publication number: WO2021087681A1
Application number: PCT/CN2019/115404
Authority: WO
Inventors: 田新智; 陈亮; 金铁; 陈忠平; 吴修东; 赵晓峰
Original assignee: 新里程医用加速器(无锡)有限公司
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2021-05-14
Also published as: CN112055602B; CN112055602A

Abstract

Provided is a cone-beam-based helical volumetric modulated radiation therapy device, comprising a fixed rack (100); a rotary rack (101) arranged on the fixed rack (100), the rotary rack (101) having a middle channel; a microwave system (200) arranged on the rotary rack (101) and used for generating rays; a therapy head (300) arranged on the rotary rack (101) and used for modulating the rays generated by the microwave system (200) into a cone beam; and a therapy bed (400) arranged on one side of the rotary rack (101), the therapy bed (400) being capable of moving in X, Y and Z in a three-dimensional space coordinate system relative to the rotary rack (101). In addition, a cone-beam-based helical volumetric modulated image system is further provided. The radiation therapy device can be combined with stepping of the cone beam and the therapy bed (400), such that different doses are applied to different target areas, and the range of irradiation fits better to the shape of a tumor, thereby improving the tumor control rate, reducing side effects of radiation therapy, and prolonging patient survival time.

Description

Cone beam-based spiral volume intensity modulated radiotherapy device and imaging system

Technical field

The invention relates to a radiotherapy device, in particular to a spiral volume intensity modulated radiotherapy device based on a cone beam, and also relates to an imaging system including the radiotherapy device.

Background technique

The radiotherapy device is a large-scale long-distance radiotherapy equipment used for cancer treatment. It generates X-rays and electronic rays to directly irradiate the tumor in the patient's body outside the body, thereby achieving the purpose of eliminating or reducing the tumor. At present, there are two types of common radiotherapy devices: C-arm and O-arm. Relatively speaking, the structure of O-arm device is more compact and closed. It has more advantages in the implementation of more and more automation and intelligent radiotherapy technology. It also has higher security. Commonly used radiotherapy techniques include Intensity Modulated Radiation Therapy (IMRT), Volumetric Modulated Arc Therapy (VMAT) and helical tomotherapy (HT).

Among them, Intensity Modulated Radiation Therapy (IMRT) has several fixed radiation fields. The position of the grating blades can be changed during each radiation field treatment process. The dose distribution of a single fixed field is better, but due to the radiation field direction It is a limited number of directions. The overall dose distribution is rougher than the gantry rotation intensity adjustment. At the same time, because the fixed field generally requires manual operation and the radiation beam needs to be stopped, the time utilization rate is not high, and the treatment time is longer. long.

Compared with fixed-field therapy, Volumetric Modulated Arc Therapy (VMAT) has better conformability with dose distribution, more accurate dose, and low dose to the organs at risk around the target area, while the tumor target area The characteristics of receiving large doses of radiation can significantly improve the efficiency of radiotherapy and reduce related side effects. At the same time, the duty cycle of the movement or work of each component device is higher, and less treatment time is required, which effectively improves the throughput of hospital patient treatment. Volumetric Modulated Arc Therapy (Volumetric Modulated Arc Therapy, VMAT) is a treatment method that combines dynamic multi-leaf grating MLC and gantry movement. While the gantry moves, the position of the MLC blades and the beam dose (Monitor Unit, MU) can be changed. ), where the frame speed, MLC blade speed, dosage and other parameters are adjustable. At present, the main models on the market are all ±180°rotation methods. The basic principle is to form one or more arcs by rotating the frame angle for continuous irradiation. When rotating, the multi-leaf grating MLC irradiates the conformal subfields generated by each angle through integration The superposition forms a dose distribution with good dose, volume, conformity and high precision. As shown in Figures 1 and 2, the accelerator of Volumetric Modulated Arc Therapy (VMAT) is basically the same as the IMRT accelerator, including the upper collimator 1', the lower collimator 2'and the multi-collimator 3' (Including the blade drive motor 31' and the blade 32' moving under the blade drive motor), there is no difference in structure except for the higher requirements for the blade speed and system control ability of the multi-element collimator.

Volumetric Modulated Arc Therapy (VMAT) has so far only been used in cases of small and medium target areas. For very large tumors or systemic lesions, fractional or segmented treatment is required. It is difficult to achieve multi-target or large-target treatment. The seams are connected, and the super-large tumor treatment dose field has the characteristics of cold and hot spots and different dose values, which brings toxic and side effects to patients. At the same time, the work efficiency of this treatment method is low.

Helical tomotherapy (helical tomotherapy, HT) is a CT scan with 360° continuous rotation and a narrow fan beam for spiral irradiation to achieve intensity-modulated radiotherapy. Specifically, a long and narrow collimator (binary pneumatic collimator) is installed on the traditional machine to obtain a fan beam with a width of about 20 cm and a layer thickness of 1-4 cm. As shown in Figure 3, as the gantry rotates, the fan beam can form a strip-shaped irradiation field on the cross section of the patient. During the rotation of the frame, the blades of the collimator enter and exit under the control of the computer to adjust the opening or closing time of each sector to achieve the purpose of strengthening. At the same time, with the stepping movement of the treatment bed, it can cover the treatment of super-large tumors.

This kind of equipment adopting spiral stepping intensity modulation method can treat multiple lesions at the same time in the same positioning interval. And for longer radiation fields (such as total central irradiation, large-area irregular lymphatic drainage area irradiation and spinal tumors, etc.), there is no need to separate fields and complete them at one time, avoiding the appearance of cold spots or hot spots, improving tumor control rate and reducing Damage to normal tissues. However, compared with the VMAT radiotherapy technology under cone beam conditions, the use of fan beam spiral intensity modulation equipment has a low utilization rate of radiation. To treat the entire target area, it is necessary to irradiate several narrow fields in sequence, so it is relatively The treatment time of VMAT is relatively long, and the treatment efficiency is reduced. In terms of time, a VMAT treatment takes about 2-3 minutes, and to complete the same treatment, it takes 15-30 minutes to use fan beam treatment.

Summary of the invention

In view of the problems in the background art, the present invention provides a cone beam-based spiral volume intensity modulated radiotherapy device, including:

Fixed frame

A rotating frame arranged on the fixed frame, the rotating frame has a middle channel, and the rotating frame can rotate 360° along a horizontal B axis relative to the fixed frame;

A microwave system for generating rays arranged on the rotating gantry;

A treatment head arranged on the rotating gantry for modulating the rays generated by the microwave system into a cone beam, the treatment head being capable of rotating 360° along the vertical A axis relative to the rotating gantry;

A treatment bed arranged on one side of the rotating gantry, the treatment bed being able to move relative to the rotating gantry in a three-dimensional space coordinate system X, Y, Z, so that it can enter or leave via the middle channel The rotating frame.

The cone-beam-based spiral volume-modulated radiotherapy device provided by the present invention can combine the stepping of the cone beam and the treatment bed to implement different doses to different target areas, high-dose tumor target areas, low-dose surrounding normal tissues, and irradiate The range is more suitable for the shape of the tumor, which improves the tumor control rate, improves the protection of risk organs, reduces the side effects of radiotherapy, and improves the survival time of patients.

In addition, the radiotherapy device has higher target area accuracy and achieves sub-millimeter target area accuracy errors. It can complete extremely complex intensity modulation planning schemes that cannot be completed by traditional radiotherapy devices, improve work efficiency, and allow more patients to perform radiation Treatment reduces the labor intensity of doctors who perform radiotherapy work and reduces the requirements of radiological physicists.

In some embodiments of the present invention, the cone beam-based spiral volume-modulated radiotherapy device includes a first solenoid valve arranged on the rotating gantry or the fixed gantry, so that both can pass through the first solenoid valve. A solenoid valve is locked.

In some embodiments of the present invention, the rotating frame has a cantilever extending parallel to the B axis; the microwave system includes a modulator, a magnetron, a circulator, a grid-controlled gun power supply, a grid-controlled gun, and an acceleration The modulation modulator controls the magnetron, the magnetron is connected to the acceleration tube through a circulator, and the grid control gun power supply is used to control the grid control gun injection voltage and Electric current to make the grid control gun output an electron beam, the accelerator tube accelerates the electron beam and makes it hit the accelerator tube target to generate an X-ray beam, and the central axis of the X-ray generated by the microwave system coincides with the A axis , And the A axis and the B axis intersect at the isocenter point I.

In some embodiments of the present invention, the treatment head and the rotating gantry are connected by a cantilever and are located below the accelerating tube target, and the treatment head includes:

Fixing the primary collimator nested on the cantilever;

An ionization chamber fixedly arranged on the cantilever and located below the primary collimator for ionizing inert gas to generate an output electrical signal;

A secondary collimator fixedly arranged on the cantilever and located below the ionization chamber;

A double-layer multi-leaf grating located under the secondary collimator, the double-layer multi-leaf grating is connected to the cantilever shaft, so that the double-layer multi-leaf grating can rotate 360° along the vertical A axis.

The treatment head of the cone beam-based spiral volume intensity modulated radiotherapy device provided by the present invention adopts a combination of a primary collimator, a secondary collimator, and a rotating double-layer multi-leaf grating to modulate the rays emitted by the microwave system into a cone Beam, and then coordinate with the movement of the treatment bed to achieve precise radiotherapy of the target area.

In some embodiments of the present invention, the treatment head includes a homogenizer that is fixedly disposed on the primary collimator and can filter low-energy X-rays to form evenly distributed high-energy X-rays.

In some embodiments of the present invention, the double-layer multi-leaf grating includes:

The upper independent collimator or the upper multi-element collimator, and the lower multi-element collimator that are fixedly connected to each other; or

The lower independent collimator or the lower multi-element collimator, and the upper multi-element collimator that are fixedly connected to each other.

In some embodiments of the present invention, the cone beam-based spiral volume-modulated radiotherapy device includes a second solenoid valve disposed on the double-layer multi-leaf grating or the cantilever, so that the two can Locked by the second solenoid valve.

In some embodiments of the present invention, the treatment bed includes:

Bottom plate

A single scissors support structure provided on the bottom plate and a first driving device for driving the single scissors support mechanism to complete the Z-direction movement;

A first bearing plate with an X-direction unit provided on the single scissors support structure;

A second supporting plate capable of moving along the X-direction unit and a second driving device for driving the second supporting plate to move along the X-direction unit provided on the first supporting plate, the second supporting plate With Y-direction unit;

A third supporting plate capable of moving along the Y-direction unit and a third driving device for driving the third supporting plate to move along the Y-direction unit are arranged on the second supporting plate.

In some embodiments of the present invention, the rotation speed of the rotating gantry, the number of machine hops of the radiotherapy device, the movement speed of the blades of the double-layer multi-leaf grating, and the movement speed of the treatment bed satisfy the following conditions:

Δθ/Δt≤(dθ/dt) _max ;

ΔMU/Δt≤(dMU/dt) _max ;

Δx/Δt≤(dx/dt) _max ;

Δy/Δt≤(dy/dt) _max ;

Where θ, MU, x, and y respectively represent the rotation speed of the rotating gantry, the number of machine hops of the radiotherapy device, the movement displacement of the double-layer multi-leaf grating, and the movement displacement of the treatment bed;

(dθ/dt) _max , (dMU/dt) _max , (dx/dt) _max , (dy/dt) _max respectively represent the maximum speed of the rotating frame, the maximum dose rate of the accelerator, and the maximum speed of the double-layer multi-leaf grating And the maximum speed of the treatment bed.

Based on the speed limitations of the above components, the control algorithm can plan the motion control of the accelerator's spiral VMAT treatment mode, that is, every time the rotating gantry rotates one degree, the grating position of the treatment head changes in real time to conform to the shape of the target area of the treatment field. The dose rate is also changing to ensure the accuracy of the radiation therapy dose. At the same time, the treatment bed runs at a uniform speed. When the treatment bed covers the entire tumor area, the patient's treatment is completed.

In addition, the present invention also provides a cone beam-based spiral volume intensity modulation imaging system, including:

The above-mentioned cone beam-based spiral volume-modulated radiotherapy device and MV imaging system;

The MV imaging system includes:

An MV detector arranged on the rotating gantry for collecting X-rays penetrating the treatment bed;

The main beam shielding assembly arranged on the rotating gantry and located under the MV detector;

The MV detector and the beam main shielding assembly are both located on the opposite side of the treatment head.

The MV imaging system and the treatment head 300 provided by the present invention work at the same time, so that the MV imaging system can complete the quality assurance (QA) function of the radiotherapy device, such as the verification of the center position of the radiotherapy device, and the positioning of the double-layer multi-leaf grating 305 Accuracy verification and dose verification of accelerator treatment field, etc.

In some embodiments of the present invention, the cone-beam-based spiral volume modulation imaging system further includes a KV-level energy X-ray-based CBCT imaging system, and the CBCT imaging system includes:

A high-voltage generator for outputting high-voltage CBCT arranged on the rotating frame;

A CBCT tube capable of generating KV-level X-rays with corresponding energy under the control of the CBCT high-voltage generator and arranged on the rotating gantry;

A KV beam limiting device arranged on the rotating gantry and located at the front end of the CBCT tube;

A KV detector arranged on the rotating gantry and located on the opposite side of the CBCT tube;

The center line of the KV class X-ray generated by the CBCT tube and the B axis intersect at the isocenter point I.

The KV ray-based CBCT system provided by the present invention has multiple applications, such as monitoring of the patient's position during treatment, and patient's position verification before treatment. The high-voltage generator, CBCT tube, and image detector form an image acquisition system. First, the acquisition system collects and transmits the projection data sequence to the CBCT workstation for 3D reconstruction, and then the reconstructed CBCT volume data and the radiotherapy planning system CT image are used for 3D volume registration , And finally get the patient's positioning error. If the error exceeds the specified positioning deviation requirement, the imaging system will transmit the deviation to the motion control system. The motion control system controls the movement of the treatment bed to eliminate the artificial positioning error, and finally performs accurate positioning on the patient. Radiation Therapy.

Description of the drawings

Fig. 1 is a schematic diagram of the structure of a multi-element collimator 3'in the prior art;

Figure 2 shows the formation of a cone beam conformal field in the prior art;

Figure 3 shows the formation of a fan beam conformal field in the prior art;

4 is a schematic diagram of the overall structure of a spiral volume-modulated radiotherapy device based on a cone beam according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a microwave system 200 in an embodiment of the present invention;

6 is a schematic diagram of the structure of the treatment head 300 in an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a treatment bed 400 in an embodiment of the present invention;

FIG. 8 is a working flow chart of an MV imaging system application in an embodiment of the present invention;

9 is a working flow chart of a CBCT imaging system based on KV energy X-rays in an embodiment of the present invention;

Fig. 10 is a schematic diagram of a spiral volume-modulated radiotherapy device based on a cone beam provided by the present invention that generates spiral rays surrounding the human body.

Description of reference signs :

Fixed frame 100;

Rotating frame 101;

Cantilever 102;

Microwave system 200: modulator 201; magnetron 202; circulator 203; grid control gun power supply 204; grid control gun 205; acceleration tube 206; acceleration tube target 207;

Treatment head 300: primary collimator 301; homogenizer 302; ionization chamber 303; secondary collimator 304; double-layer multi-leaf grating 305; upper independent collimator or upper multi-element collimator 305-1; lower independent collimator Straightener or lower multi-element collimator 305-2;

The treatment bed 400: a bottom plate 401, a single scissors support structure 402, a first driving device 403, a first supporting board 404, a second supporting board 405, a second driving device 406, a third supporting board 407, and a third driving device 408.

Detailed ways

In order to make the objectives, technical solutions and advantages of the invention clearer, the invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Although the drawings show exemplary embodiments of the present disclosure, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to facilitate a thorough understanding of the present invention and to fully convey the concept of the present invention to those skilled in the art.

Example one

Referring to FIG. 4, the cone beam-based spiral volume-modulated radiotherapy apparatus provided in this embodiment includes a fixed gantry 100, a rotating gantry 101, a microwave system 200, a treatment head 300, and a treatment bed 400. The above-mentioned rotating frame 101 is arranged on the fixed frame 100, and the rotating frame 101 can rotate 360° along the horizontal axis B in FIG. 4 relative to the fixed frame 100 (the rotating frame 101 can be mounted on the fixed frame in a shaft connection manner). 100 on the shelf). The rotating gantry 101 is roughly cylindrical, with a hollow channel in the middle, which can allow the treatment bed 400 carrying the patient to pass through (enter or leave). The microwave system 200 is installed on the rotating gantry 101 and can control and generate X-rays. The treatment head 300 is disposed on the rotating machine 101, and the treatment head 200 can rotate 360° along the vertical axis A in FIG. 4 relative to the rotating frame 101. The treatment head 300 can modulate the X-rays generated by the microwave system 200 into a cone beam. The treatment bed 400 is arranged on one side of the rotating gantry 101 (shown as the left side in FIG. 4), which can move relative to the rotating gantry 101 in the three-dimensional space coordinate system X, Y, and Z shown in the figure, so that It can enter or leave the rotating frame 101 via the middle passage.

Further, the rotating frame 101 has a cantilever 102 extending in a direction parallel to the B axis, and the microwave system 200 is fixedly arranged on the cantilever 102. As shown in FIG. 5, the microwave system 200 includes a modulator 201, a magnetron 202, a circulator 203, a grid control gun power supply 204, a grid control gun 205, an acceleration tube 206 and an acceleration tube target 207. All components are arranged on the rotating frame 101 of the accelerator. The relationship between the components is shown in FIG. 5, the modulator 201 controls the magnetron 202, and the magnetron 202 is connected to the acceleration tube 206 through the circulator 203. The grid control gun power supply 204 is used to control the injection voltage and current of the grid control gun 205, and the grid control gun 205 outputs an electron beam. At the same time, the electron beam is accelerated by the acceleration tube 206 and hits the acceleration tube target 207 to generate an X-ray beam. The central axis of the X-ray generated by the microwave system 200 coincides with the A-axis, and the A-axis and the B-axis intersect at the isocenter I

As shown in FIG. 6, the treatment head 300 includes a primary collimator 301, a homogenizer 302, an ionization chamber 303, a secondary collimator 304 and a double-layer multi-leaf grating 305 arranged in sequence. Specifically, as shown in FIG. 4, the treatment head 300 is located under the accelerating tube target 207 of the microwave system 200, and the primary collimator 301 is fixedly nested on the cantilever 102. The homogenizer 302 is fixedly arranged on the primary collimator 301, and is used to filter out low-energy rays to form evenly distributed high-energy rays. The ionization chamber 303 is fixedly arranged on the cantilever 102 and located under the primary collimator 301, and is used to ionize the inert gas to generate an output electrical signal, and to perform statistics on the dose emitted by the accelerator. The secondary collimator 304 is fixedly arranged on the cantilever 102 and located under the ionization chamber 303, and is used to collimate the X-ray into a cone beam with a square cross-section. The double-layer multi-leaf grating 305 is located below the secondary collimator 304, and the double-layer multi-leaf grating 305 is axially connected to the cantilever 102, so that the double-layer multi-leaf grating 305 can rotate 360° along the vertical A axis. It is mainly used to provide conformal positioning of the irradiation field during treatment or plan verification, and to provide support for precise treatment.

Further, the radiotherapy device also supports a flattening filter free (FFF) treatment mode. In this mode, the flattening filter 302 can be moved out of the radiation irradiation area, and the radiation without flattening becomes softer than the radiation quality, and the photon flux increases.

Further, the double-layer multi-leaf grating 305 includes an upper independent collimator or an upper multi-element collimator 305-1 and a lower multi-element collimator 305-2 that are fixedly connected to each other. Or, the upper layer multi-element collimator 305-1, the lower layer independent collimator or the lower layer multi-element collimator 305-2 fixedly connected to each other. That is, the above-mentioned double-layer multi-leaf grating 305 does not use a combination of an upper-layer independent collimator and a lower-layer independent collimator.

Further, the cone beam-based spiral volume modulated radiotherapy device includes a first solenoid valve (not shown) arranged on the rotating gantry 101 or the fixed gantry 100, so that the two can be locked by the first solenoid valve . The control system controls the operation of the first solenoid valve. When the rotating gantry 101 rotates to a predetermined angle relative to the fixed gantry 100 during treatment, the two are locked by the first solenoid valve, and the treatment head 300 modulates the cone beam radiation treatment The patient on the bed 400, until the treatment of the predetermined part of the patient is completed, the first solenoid valve fails, and the rotating frame 101 rotates to the next predetermined angle relative to the fixed frame 100.

Further, the cone beam-based spiral volume modulation radiotherapy device includes a second solenoid valve (not shown) provided on the double-layer multi-leaf grating 305 or the cantilever 102, so that the two can pass through the second solenoid valve. The valve is locked. The function of the second solenoid valve is similar to that of the first solenoid valve, and is used to ensure that the double-layer multi-leaf grating 305 will not rotate relative to the cantilever 102 during the treatment process.

As shown in FIG. 7, further, the above-mentioned treatment bed 400 includes a bottom plate 401, a single scissors support structure 402, a first driving device 403, a first supporting board 404, a second supporting board 405, a second driving device 406, and a third Carrying board 407, third driving device 408.

Specifically, the single scissors supporting structure 402 and the first driving device 403 are both arranged on the bottom plate 401, and the bottom of the X-shaped single scissors supporting structure 402 and the bottom plate 401 are slidably arranged, so that it can be realized under the driving of the first driving device 403. Z-direction movement (such as the Z-direction in Figure 4), that is, to achieve raising and lowering. The first bearing plate 404 is arranged on the single scissors support structure 402 so that it can follow the single scissors support structure 402 to move in the Z direction. The first supporting board 404 has an X-direction unit (the X-direction as shown in FIG. 4, and the X-direction unit in this embodiment is represented as a slide rail). The second bearing plate 405 and the second driving device 406 are both arranged on the first bearing plate 404, and the lower part of the second bearing plate 405 has a structure that matches the X-direction unit (in this embodiment, a slider moving along a guide rail can be used). ), so that under the driving of the second driving device 406, the second bearing plate 405 realizes the X-direction movement along the first bearing plate 404. A Y-direction unit (the Y-direction as shown in FIG. 1, and the Y-direction unit in this embodiment is represented by a screw) is provided on the second bearing plate 405. The third bearing plate 407 and the third driving device 408 are arranged on the second bearing plate 405, and the lower part of the third bearing plate 407 is provided with a structure matching the above-mentioned Y-direction unit (in this embodiment, the movement along the lead screw can be used). Screw nut), so that under the driving of the third driving device 408, the third bearing plate 407 realizes the Y-direction movement along the second bearing plate 405.

Example two

As shown in Figure 4, in this embodiment, the cone-beam-based helical volume-modulated radiotherapy device has a more advanced imaging system configuration, and this part of the components can be selected according to economic conditions. The imaging system includes MV imaging system and CBCT imaging system based on KV energy X-ray.

The MV imaging system includes the above-mentioned cone beam-based spiral volume modulation radiotherapy device, an MV detector 107, and a beam main shielding assembly 108. The MV detector 107 and the beam main shielding assembly 108 are both installed on the rotating gantry 101, and they are directly below the treatment head 300 (located on the opposite side of the treatment head 300), and the beam main shielding assembly 108 is located at the MV detection Below the device 107.

The CBCT imaging system based on KV energy X-rays includes a KV beam limiting device 103, a CBCT tube 104, a CBCT high-voltage generator 105, and a KV detector 106. The components of the CBCT imaging system are all arranged on the rotating gantry 101, wherein the KV beam limiting device 103 and the CBCT tube 104 are installed together, and the KV detector 106 is arranged on the rotating gantry opposite to the CBCT tube 104. The working principle is that when the CBCT high-voltage generator 105 outputs high voltage to the CBCT tube 104, the CBCT tube 104 can be controlled to generate KV-level X-rays with corresponding energy, and the X-rays are transmitted to the KV detector 106 through the KV beam limiting device 103. The generated X-ray centerline and the B axis intersect at the isocenter point I.

Furthermore, the MV imaging system has many applications. In the absence of a CBCT imaging system based on KV-level energy X-rays, the MV imaging system can collect the projection of the angular position of the two rotating gantry 101 to achieve the patient before treatment. Placement verification. At the same time, because the MV imaging system and the treatment head 300 work at the same time, the MV imaging system can complete the quality assurance (QA) function of the radiotherapy device, such as the verification of the central position of the radiotherapy device, and the verification of the positioning accuracy of the double-layer multi-leaf grating 305 And the dose verification of the treatment field of the radiotherapy device.

Figure 8 shows the workflow of the MV imaging system application, where the MV imaging detector 107 and the treatment head 300 form an image acquisition system. First, the acquisition system collects projection data. The collected data can be used for two-dimensional registration or a radiotherapy device. QA function. If the registration function is performed, the data is transmitted to the MV two-dimensional registration system, and then the projection data is collected and the digitally reconstructed radiograph (DRR) in the radiotherapy planning system is used for two-dimensional registration, and finally the patient's Set-up error, if the error exceeds the specified set-up deviation requirements, the imaging system will transmit the deviation to the motion control system. The motion control system controls the movement of the treatment bed 400 to eliminate man-made positioning errors, and finally perform accurate radiotherapy on the patient. If the QA function of the radiotherapy device is realized, the collected projection data will be transmitted to the MV QA system, and then the system will analyze the projection data to obtain relevant machine QA or radiation field-related information, such as dose flatness, symmetry, and dose The QA analysis report can be printed out at the end.

Furthermore, the CBCT system based on KV rays has many applications, such as monitoring the patient's position during treatment, and verifying the patient's position before treatment. Figure 9 shows an application process of the CBCT imaging system in patient positioning verification. The high-voltage generator 105, the CBCT tube 104, and the image detector 106 constitute an image acquisition system. First, the acquisition system collects and transmits the projection data sequence to the CBCT workstation for 3D reconstruction, and then the reconstructed CBCT volume data and radiotherapy planning system CT images are used for 3D reconstruction. Volume registration, and finally get the patient's positioning error. If the error exceeds the specified positioning deviation requirements, the imaging system will transmit the deviation to the motion control system. The motion control system controls the movement of the treatment bed 400 to eliminate the artificial positioning error. The patient undergoes precise radiotherapy.

Further, the cone beam-based spiral volume-modulated radiotherapy device provided in this embodiment has a spiral VMAT-based treatment method. The existing VMAT treatment technology is suitable for relatively small tumor target areas and can complete irradiation treatment at one time. This technology is also a relatively mature technology. In summary, it can be considered as a subset of spiral VMAT. This device also supports VMAT treatment. Because of the more mature technology, I won't repeat it here. Compared with the traditional VMAT treatment method, the spiral VMAT treatment method is suitable for the treatment of large tumors, and has higher efficiency, smoother dose distribution, higher conformity, and more accurate dose distribution. Spiral VMAT can complete the treatment of all the lesions after a patient is placed, without the need for traditional technology to switch to multi-center treatment. After the traditional treatment method is switched to the repositioning of the center, it is a new treatment and requires positioning and verification operations. Relatively speaking, the spiral VMAT takes less time. In particular, this treatment method is safer, because the treatment process can be fully automated without manual intervention in the middle process, which reduces the possibility of human error. Since the entire target area is treated by moving the bed at a uniform speed during the whole process, this method can ensure the accuracy of the modulation of the dose intensity through exercise, and ensure that the dose conformity of the target area is better.

Further, in conjunction with Figure 10, to treat a large tumor, the spiral VMAT treatment technology needs to be used. To realize the treatment of spiral VMAT, the key is to control the movement of the moving parts of the accelerator and the X-ray beam to achieve the coordinated and precise work of the parts. The component parameters that need to be controlled include the speed of the rotating gantry 101, the number of machine hops of the radiotherapy device, the motion speed of the blades of the double-layer multi-leaf grating 305, and the motion speed of the treatment bed 400. The parameter restriction conditions of each component are as follows:

Δθ/Δt≤(dθ/dt) _max ,

ΔMU/Δt≤(dMU/dt) _max ,

Δx/Δt≤(dx/dt) _max ,

Δy/Δt≤(dy/dt) _max ,

Where θ, MU, x, and y respectively represent the rotation speed of the rotating gantry 101, the number of machine hops of the radiotherapy device (dose monitoring uses the number of machine hops MU as the display unit), the movement displacement of the double-layer multi-leaf grating 305, and the treatment bed 400 The movement displacement. (dθ/dt) _max , (dMU/dt) _max , (dx/dt) _max , (dy/dt) _max represent the maximum speed of the rotating gantry 101, the maximum dose rate of the accelerator, and the double-layer multi-leaf grating 305 The maximum speed and the maximum speed of the treatment couch. When executing the patient's treatment plan, each device must not exceed the maximum speed of its own machine, otherwise the accelerator's interlocking system will report interlocking, and the interlocking interface will give corresponding prompt information and methods to remove interlocking. The rotating gantry 101 of the accelerator is designed to support a speed of 6 revolutions per minute. If the speed used during treatment is one revolution per minute, in order to ensure safety during treatment, the running speed of the gantry may be reduced, and the high-speed gantry rotates Modes are more used in imaging and verification functions.

Then the maximum speed of the movement of the gantry at this time is (dθ/dt) _max = 6deg/s. By setting the maximum speed of the double-layer multi-leaf grating 305 (dx/dt) _max ＝6cm/s, the rotating gantry 101 can be obtained. The displacement of the largest double-layer multi-leaf grating 305 corresponding to each rotation is 1 cm, namely:

(dx/dθ) _max = (dx/dt) _max /(dθ/dt) _max = 1 cm/deg.

Similarly, by setting the maximum dose rate of the accelerator (dMU/dt) _max = 800MU/min, it can be obtained that the number of machine hops corresponding to one degree of rotation of the rotating frame 101 is approximately 2.2 MU, namely:

(dMU/dθ) _max = (dMU/dt) _max /(dθ/dt) _max = 2.2 MU/deg.

At the same time, the maximum dose rate of the accelerator in this embodiment is supported to 1200 MU/min.

Similarly, by setting the maximum speed of the treatment bed 400 (dy/dt) _max = 6cm/s, it can be obtained that the maximum displacement of the treatment bed 400 corresponding to one degree of rotation of the rotating gantry 101 is 1 cm/s, namely:

(dy/dθ) _max = (dy/dt) _max /(dθ/dt) _max = 1 cm/deg.

In order to better ensure the accuracy of the treatment during the treatment process, the movement speed of the treatment bed 400 of the radiotherapy device in this embodiment is set as an unchangeable parameter. In summary, in the process of implementing the spiral VMAT, every time the rotating gantry 101 rotates one degree, the grating position of the treatment head 300 changes in real time to conform to the shape of the target area of the treatment field, and the dose rate is also changing to ensure radiotherapy The accuracy of the dose, while the treatment bed 400 runs at a uniform speed, when the treatment bed 400 covers the entire tumor area, the treatment of the patient is completed.

Further, the radiotherapy device provides a real-time dose statistics function. When a deviation occurs in the execution of the treatment plan, the BGM (Beam Generator Module) system of the radiotherapy device can be within the allowable range of the deviation of the rotating gantry 101 and the dose. Adjust the dose rate to compensate. When the dose is under-dose, increase the dose rate, but the dose rate cannot exceed the range of the dose rate supported by the machine itself, otherwise the system will report the chain of under-dose. When the dose is too large, lower the dose rate, and the same dose rate cannot exceed the range of the dose rate supported by the machine, otherwise the system will report a chain of excessive dose.

Further, when there is deviation in the execution of the treatment plan, the BGM (Beam Generator Module) system of the radiotherapy device can adjust the speed of the rotating gantry 101 to compensate within the allowable range of the deviation between the deflection of the rotating gantry 101 and the dose. When the dose is under-dose, reduce the speed of the rotating frame 101. When the dose is too large, increase the speed of the rotating frame 101, but the rotating speed cannot exceed the maximum value of the rotating speed supported by the machine itself, otherwise the system will report an overdose chain.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that modifications or equivalent replacements to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and should be covered by the present invention. Within the scope of the claims of the invention.

Claims

The spiral volume intensity modulated radiotherapy device based on cone beam is characterized in that it comprises:

Fixed frame (100);

A rotating frame (101) arranged on the fixed frame (100), the rotating frame (101) has a middle channel, and the rotating frame (101) can be relative to the fixed frame (100) 360° rotation along the horizontal B axis;

A microwave system (200) for generating rays arranged on the rotating gantry (101);

A treatment head (300) arranged on the rotating gantry (101) for modulating the rays generated by the microwave system (200) into a cone beam, the treatment head (300) being able to rotate relative to the The frame (101) rotates 360° along the vertical A axis;

A treatment bed (400) arranged on one side of the rotating gantry (101), the treatment bed (400) being able to move in a three-dimensional space coordinate system X, Y, Z relative to the rotating gantry (101), So that it can enter or leave the rotating frame (101) via the middle passage.
The cone beam-based spiral volume-modulated radiotherapy device according to claim 1, characterized in that it comprises:

The first solenoid valve is arranged on the rotating frame (101) or the fixed frame (100), so that the two can be locked by the first solenoid valve.
The cone beam-based spiral volume-modulated radiotherapy device according to claim 1, wherein the rotating gantry (101) has a cantilever (102) extending parallel to the B-axis direction; the microwave system ( 200) includes a modulator (201), a magnetron (202), a circulator (203), a grid control gun power supply (204), a grid control gun (205), an acceleration tube (206) and an acceleration tube target (207); The modulation modulator (201) controls the magnetron (202), the magnetron (202) is connected to the accelerating tube (206) through a circulator (203), and the grid control gun power supply (204) ) Is used to control the injection voltage and current of the grid control gun (205) so that the grid control gun (205) outputs an electron beam, and the acceleration tube (206) accelerates the electron beam to make it hit the acceleration tube The target (207) generates an X-ray beam, the central axis of the X-ray generated by the microwave system (200) coincides with the A axis, and the A axis and the B axis intersect at the isocenter I.
The cone beam-based spiral volume-modulated radiotherapy device according to claim 3, wherein the treatment head (300) and the rotating gantry (101) are connected by a cantilever (102), and are located in the Below the accelerating tube target (207), the treatment head (300) includes:

Fixing the primary collimator (301) nested on the cantilever (102);

An ionization chamber (303) fixedly arranged on the cantilever (102) and located below the primary collimator (301) for ionizing inert gas to generate an output electrical signal;

A secondary collimator (304) fixedly arranged on the cantilever (102) and located below the ionization chamber (303);

The double-layer multi-leaf grating (305) located below the secondary collimator (304), the double-layer multi-leaf grating (305) and the cantilever (102) are axially connected so that the double-layer multi-leaf The grating (305) can rotate 360° along the vertical A axis.
The cone-beam-based spiral volume-modulated radiotherapy device according to claim 4, wherein the treatment head (300) comprises:

A homogenizer (302) which is fixedly arranged on the primary collimator (301) and can filter low-energy X-rays to form a uniformly distributed high-energy X-ray.
The cone-beam-based spiral volume-modulated radiotherapy device according to claim 4, wherein the double-layer multi-leaf grating (305) comprises:

The upper independent collimator or the upper multi-element collimator (305-1) and the lower multi-element collimator (305-2) fixedly connected to each other; or

The lower independent collimator or the lower multi-element collimator (305-2), and the upper multi-element collimator (305-1) fixedly connected to each other.
The cone beam-based spiral volume-modulated radiotherapy device according to claim 4, characterized in that it comprises:

A second solenoid valve arranged on the double-layer multi-leaf grating (305) or the cantilever (102), so that the two can be locked by the second solenoid valve.
The cone-beam-based spiral volume-modulated radiotherapy device according to claim 4, characterized in that the treatment bed (400) comprises:

Base plate (401);

A single scissors support structure (402) provided on the bottom plate (401) and a first driving device (403) for driving the single scissors support mechanism (402) to complete Z-direction movement;

A first bearing plate (404) with an X-direction unit provided on the single scissors support structure (402);

A second supporting plate (405) that is arranged on the first supporting plate (404) and capable of moving along the X-direction unit and a second supporting plate (405) for driving the second supporting plate (405) to move along the X-direction unit The driving device (406), the second bearing plate (405) has a Y guide unit;

A third bearing plate (407) that is arranged on the second bearing plate (405) and capable of moving along the Y-direction unit and a third bearing plate (407) for driving the third bearing plate (407) to move along the Y-direction unit Drive device (408).
The cone-beam-based spiral volume-modulated radiotherapy device according to claim 8, wherein the rotation speed of the rotating frame (101), the number of machine hops of the radiotherapy device, and the double-layer multi-leaflet The moving speed of the blades of the grating (305) and the moving speed of the treatment bed (400) meet the following conditions:

Δθ/Δt≤(dθ/dt) max ;

ΔMU/Δt≤(dMU/dt) max ;

Δx/Δt≤(dx/dt) max ;

Δy/Δt≤(dy/dt) max ;

Where θ, MU, x, and y respectively represent the rotation speed of the rotating gantry (101), the number of machine hops of the radiotherapy device, the movement displacement of the double-layer multi-leaf grating (305), and the movement displacement of the treatment bed (400);

(dθ/dt) max , (dMU/dt) max , (dx/dt) max , (dy/dt) max respectively represent the maximum speed of the rotating gantry (101), the maximum dose rate of the accelerator, and the double-layer multi-leaf grating The maximum speed of (305) and the maximum speed of the treatment couch (400).
The cone beam-based spiral volume intensity modulation imaging system is characterized in that it includes:

The cone beam-based spiral volume-modulated radiotherapy device and MV imaging system according to any one of claims 1-9;

The MV imaging system includes:

An MV detector (107) arranged on the rotating gantry (101) for collecting X-rays penetrating the treatment bed (400);

The main beam shielding assembly (108) arranged on the rotating gantry (101) and located below the MV detector (107);

The MV detector (107) and the beam main shielding assembly (108) are both located on the opposite side of the treatment head (300).
The imaging system based on cone beam-based spiral volume modulation of claim 10, further comprising a CBCT imaging system based on KV energy X-rays, the CBCT imaging system comprising:

A high-voltage CBCT high-voltage generator (105) arranged on the rotating frame (101) for outputting high-voltage;

A CBCT tube (104) capable of generating KV-level X-rays with corresponding energy under the control of the CBCT high-voltage generator (105) is arranged on the rotating gantry (101);

A KV beam limiting device (103) arranged on the rotating gantry (101) and located at the front end of the CBCT tube (104);

A KV detector (106) arranged on the rotating gantry (101) and located on the opposite side of the CBCT tube (104);

The center line of the KV class X-ray generated by the CBCT tube (104) and the B axis intersect at the isocenter point I.