CN112055602A

CN112055602A - Spiral volume intensity modulated radiotherapy device based on conical beam and imaging system

Info

Publication number: CN112055602A
Application number: CN201980011708.8A
Authority: CN
Inventors: 田新智; 陈亮; 金铁; 陈忠平; 吴修东; 赵晓峰
Original assignee: Xinlicheng Medical Accelerator Wuxi Co ltd
Current assignee: Xinlicheng Medical Accelerator Wuxi Co ltd
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2020-12-08
Anticipated expiration: 2039-11-04
Also published as: WO2021087681A1; CN112055602B

Abstract

A helical volume intensity modulated radiotherapy device based on a cone-beam comprises a fixed frame (100); the rotating rack (101) is arranged on the fixed rack (100), and the rotating rack (101) is provided with a middle channel; a microwave system (200) arranged on the rotating frame (101) for generating radiation; a treatment head (300) arranged on the rotating frame (101) and used for modulating the rays generated by the microwave system (200) into a conical beam; a treatment couch (400) disposed to a side of the rotating gantry (101), the treatment couch (400) being movable relative to the rotating gantry (101) under a three-dimensional spatial coordinate system X, Y, Z. In addition, a helical volume intensity modulated imaging system based on the cone beam is also provided. The radiotherapy device can mutually combine the stepping of the conical beam and the treatment couch (400), different doses are applied to different target areas, the irradiation range is more suitable for the shape of the tumor, the tumor control rate is improved, the radiotherapy side effect is reduced, and the life cycle of a patient is prolonged.

Description

Spiral volume intensity modulated radiotherapy device based on conical beam 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 conical beam, and further relates to an image system comprising the radiotherapy device.

Background

Radiotherapy apparatus is a large-scale remote radiotherapy apparatus for cancer treatment, which generates X-rays and electron beams to directly irradiate the tumor in the body of a patient in vitro, thereby achieving the purpose of eliminating or reducing the tumor. At present, a common radiotherapy device has two types of C-shaped arms and O-shaped arms, and the structure of the O-shaped arm device is more compact and more closed relatively, so that the implementation of the existing more and more automatic and intelligent radiotherapy technology is more advantageous, and meanwhile, the C-shaped arm device also has higher safety. Commonly used radiotherapy techniques are Intensity Modulated Radiation Therapy (IMRT), Volume Modulated Arc Therapy (VMAT), and Helical Tomotherapy (HT).

Wherein, Intensity Modulated Radiation Therapy (IMRT) sets up several fixed Radiation fields, can change the position of the grating blade in every Radiation field therapeutic process, the dose distribution of the single fixed field is better, but because the Radiation field direction is several directions limited, the integral dose distribution is rough to the frame rotation Intensity modulation, because generally need manual operation and ray beam-out to stop between the fixed fields at the same time, the utilization rate of the time is not high, the time of treatment is longer.

Compared with fixed-field radiotherapy, volume-Modulated Arc Therapy (VMAT) has the characteristics of better conformality of dose distribution, more accurate dose, low irradiation dose of critical organs around a target area and high irradiation dose of a tumor target area, so that the radiotherapy efficiency can be obviously improved and related side effects can be reduced. Meanwhile, the duty ratio of the movement or work of each component device is higher, less treatment time is needed, and the treatment throughput of the patients in the hospital is effectively improved. Volume rotating Modulated Arc Therapy (VMAT) is a Therapy mode combining the MLC of a dynamic multi-leaf grating with the movement of a frame, and the position of the MLC leaves and the dose of the outgoing beam (Monitor Unit, MU) can be changed while the frame moves, wherein the parameters such as the speed of the frame, the speed of the MLC leaves, the dose and the like can be adjusted. The main machine types in the market at present are in a +/-180-degree rotation mode, the basic principle is that one or more arcs are formed by rotating the angle of a frame to perform continuous irradiation, and when the multi-leaf grating MLC rotates, conformal sub-field irradiation generated by all angles is integrated and superposed to form dose distribution with good dose, volume and conformal degree and high precision. As shown in fig. 1 and 2, the Volume Modulated Arc Therapy (VMAT) accelerator and the IMRT accelerator basically include an upper collimator 1 ', a lower collimator 2 ', and a multi-element collimator 3 ' (including a leaf drive motor 31 ' and a leaf 32 ' moving under the leaf drive motor), and have no difference in structure except for higher requirements on leaf speed and system control capability of the multi-element collimator.

Volume rotating Modulated Arc Therapy (VMAT) has hitherto been used only in small and medium target volume cases, and requires fractionated or segmented treatment of ultra-large tumors or systemic lesions, which makes it difficult to achieve seamless connection of multi-target volume or large target volume treatment, and the ultra-large tumor treatment dose field has the characteristics of cold and hot spot positions and different dose values, and brings toxic and side effects to patients. Meanwhile, the treatment method has low working efficiency.

Helical Tomotherapy (HT) is a modulated intensity radiotherapy method implemented by continuously rotating 360 ° in a CT scanning manner and performing helical irradiation with a fan-shaped beam narrow-amplitude field. Specifically, a narrow collimator (binary pneumatic collimator) is mounted on a conventional machine to obtain a fan-shaped beam about 20cm wide and 1-4cm thick. As shown in fig. 3, the fan-shaped beam can form a strip-shaped radiation field on the cross section of the patient as the gantry rotates. In the rotating process 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, so as to achieve the purpose of intensity adjustment. Meanwhile, the treatment bed can cover the treatment of tumors with overlarge volume along with the stepping movement of the treatment bed.

The equipment adopting the spiral stepping intensity-adjusting mode can treat multiple focuses in the same positioning interval simultaneously. And the long radiation field (such as whole center radiation, large-area irregular lymph drainage area radiation, spondyloma and the like) is not required to be divided into fields and finished at one time, so that cold spots or hot spots are avoided, the tumor control rate is improved, and the damage to normal tissues is reduced. However, compared with the VMAT radiotherapy technique under the condition of a cone beam, the fan-beam helical intensity modulation device is adopted, the utilization rate of the radiation is low, and a plurality of narrow strip fields need to be irradiated sequentially to treat the whole target area, so that the treatment time is relatively long compared with the VMAT, and the treatment efficiency is reduced. In time terms, a VMAT treatment is approximately 2-3 minutes, while a fan beam treatment takes 15-30 minutes to complete the same treatment.

Disclosure of Invention

In view of the problems in the background art, the present invention provides a cone-beam based helical volume modulated intensity radiotherapy apparatus, comprising:

fixing the frame;

the rotating rack is arranged on the fixed rack and provided with a middle channel, and the rotating rack can rotate 360 degrees along a horizontal B axis relative to the fixed rack;

the microwave system is arranged on the rotating rack and used for generating rays;

the treatment head is arranged on the rotating rack and used for modulating the rays generated by the microwave system into a conical beam, and the treatment head can rotate 360 degrees along a vertical A axis relative to the rotating rack;

a treatment couch disposed to one side of the rotating gantry, the treatment couch being movable relative to the rotating gantry under a three-dimensional spatial coordinate system X, Y, Z such that it can enter or exit the rotating gantry via the central tunnel.

The spiral volume intensity modulated radiotherapy device based on the conical beam can apply the mutual combination of the conical beam and the stepping of the treatment couch, different doses are applied to different target areas, the tumor target area is high in dose, the surrounding normal tissues are low in dose, the irradiation range is more suitable for the shape of a tumor, the tumor control rate is improved, the protection of risk organs is improved, the toxic and side effects of radiotherapy are reduced, and the life cycle of a patient is prolonged.

In addition, this radiotherapy device's target area precision is higher, realizes sub millimeter target area precision error, and it can accomplish the very complicated accent of traditional radiotherapy device can't accomplish plan scheme, has improved work efficiency, can let more patients carry out radiotherapy, has reduced the intensity of labour who carries out radiotherapy work doctor, has reduced radiation physicist's requirement.

In some embodiments of the invention, the cone-beam based helical volume modulated intensity radiotherapy apparatus comprises a first solenoid valve disposed on the rotating gantry or the stationary gantry such that both can be locked by the first solenoid valve.

In some embodiments of the invention, the rotating gantry has a cantilever arm extending parallel to the B-axis direction; the microwave system comprises a modulator, a magnetron, a circulator, a grid-controlled gun power supply, a grid-controlled gun, an accelerating tube and an accelerating tube target; the modulator is used for controlling the magnetron, the magnetron is connected with the accelerating tube through a circulator, the grid control gun power supply is used for controlling injection voltage and current of the grid control gun so that the grid control gun outputs electron beams, the accelerating tube accelerates the electron beams and then enables the electron beams to impact the accelerating tube target to generate X-ray beams, a central shaft of the X-ray generated by the microwave system is superposed with the shaft A, and the shaft A and the shaft B are intersected at an isocenter I.

In some embodiments of the invention, the treatment head and the rotating gantry are connected by a cantilever and are located below the accelerator target, the treatment head comprising:

a primary collimator fixedly nested on the cantilever;

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

a secondary collimator fixedly arranged on the cantilever and positioned below the ionization chamber;

a double-layer multi-leaf grating located below the secondary collimator, the double-layer multi-leaf grating connected to the cantilever shaft such that the double-layer multi-leaf grating can rotate 360 ° along the vertical a axis.

The treatment head of the spiral volume intensity modulated radiotherapy device based on the conical beam realizes the modulation of the rays emitted by the microwave system into the conical beam by adopting the combination of the primary collimator, the secondary collimator and the rotary double-layer multi-leaf grating, and further realizes the precise radiotherapy of a target area by matching with the movement of the treatment couch.

In some embodiments of the invention, the treatment head comprises a homogenizer fixedly arranged on the primary collimator and capable of filtering low-energy X-rays to form a uniformly distributed high-energy X-rays.

In some embodiments of the invention, the dual layer multileaf grating comprises:

the upper independent collimator or the upper multi-element collimator and the lower multi-element collimator are fixedly connected with each other; or

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

In some embodiments of the present invention, the apparatus for cone-beam-based helical volume intensity modulated radiotherapy comprises a second solenoid valve disposed on the double-layer multi-leaf grating or the cantilever, so that the two can be locked by the second solenoid valve.

In some embodiments of the invention, the treatment couch comprises:

a base plate;

the single-scissor supporting structure is arranged on the bottom plate, and the first driving device is used for driving the single-scissor supporting structure to complete Z-direction movement;

the first bearing plate is arranged on the single-scissor supporting structure and provided with an X-direction guide unit;

the second bearing plate is arranged on the first bearing plate and can move along the X-direction guide unit, and the second driving device is used for driving the second bearing plate to move along the X-direction guide unit and is provided with a Y-direction guide unit;

the third bearing plate is arranged on the second bearing plate and can move along the Y-direction guide unit, and the third driving device is used for driving the third bearing plate to move along the Y-direction guide unit.

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

Δθ/Δt≤(dθ/dt)_max；

ΔMU/Δt≤(dMU/dt)_max；

Δx/Δt≤(dx/dt)_max；

Δy/Δt≤(dy/dt)_max；

wherein theta, MU, x and y respectively represent the rotation speed of the rotary frame, the machine jump number of the radiotherapy device, the motion displacement of the double-layer multi-leaf grating and the motion displacement of the treatment couch;

(dθ/dt)_max、(dMU/dt)_max、(dx/dt)_max、(dy/dt)_maxrepresenting the maximum speed of the rotating gantry, the maximum dose rate of the accelerator, the maximum speed of the double multi-leaf grating and the maximum speed of the couch, respectively.

Based on the speed limit of the components, the control algorithm can plan the motion control of the spiral VMAT treatment mode of the accelerator, namely, when the rotating frame rotates once, the grating position of the treatment head changes in real time to conform to the shape of the treatment field target area, and the dose rate also changes, so that the accuracy of the radiation treatment dose is ensured, meanwhile, the treatment bed runs at a constant speed, and when the treatment bed covers the whole tumor area, the treatment of the patient is completed.

In addition, the invention also provides a cone beam-based helical volume intensity modulated imaging system, which comprises:

the helical volume intensity modulated radiotherapy device based on the cone beam and the MV image system;

the MV video system comprises:

the MV detector is arranged on the rotating frame and is used for collecting X rays penetrating through the treatment couch;

a beam main shielding assembly arranged on the rotating frame and positioned below the MV detector;

the MV detector and the beam main shielding component are positioned on the right opposite sides of the therapy head.

The MV imaging system and the treatment head 300 provided by the present invention work simultaneously, so that the MV imaging system can complete the Quality Assurance (QA) function of the radiotherapy apparatus, such as verification of the center position of the radiotherapy apparatus, verification of the walking accuracy of the double-layer multi-leaf grating 305, and verification of the dose of the accelerator treatment field.

In some embodiments of the present invention, the cone-beam based helical volume-modulated imaging system further comprises a KV-level energy X-ray based CBCT imaging system, the CBCT imaging system comprising:

the CBCT high-voltage generator is arranged on the rotating rack and used for outputting high voltage;

the CBCT bulb tube is arranged on the rotating rack and can generate KV level X rays with corresponding energy under the control of the CBCT high voltage generator;

the KV beam limiting device is arranged on the rotating rack and is positioned at the front end of the CBCT bulb tube;

the KV detector is arranged on the rotating rack and is positioned on the right opposite side of the CBCT bulb tube;

the central line of KV level X ray generated by the CBCT bulb tube and the B axis are intersected at an isocenter I.

The CBCT system based on KV ray provided by the invention has various applications, such as monitoring of the position of a patient in the treatment process, verification of the position of the patient before treatment and the like. The high-voltage generator, the CBCT bulb tube and the image detector form an image acquisition system, firstly the acquisition system acquires a projection data sequence and transmits the projection data sequence to a CBCT workstation for three-dimensional reconstruction, then the reconstructed CBCT volume data and a CT image of a radiotherapy planning system are subjected to three-dimensional volume registration, finally the positioning error of a patient is obtained, if the error exceeds the specified positioning error requirement, the image system transmits the error to a motion control system, the motion control system controls the movement of the treatment table, the artificial positioning error is eliminated, and finally the patient is accurately subjected to radiotherapy.

Drawings

FIG. 1 is a schematic structural diagram of a multi-collimator 3' in the prior art;

FIG. 2 is a prior art formation of a cone beam conformal field;

FIG. 3 illustrates the formation of a fan-shaped beam conformal field in the prior art;

fig. 4 is a schematic structural diagram of a helical volume intensity modulated radiotherapy apparatus 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 according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a treatment head 300 according to an embodiment of the present invention;

FIG. 7 is a schematic view of a treatment couch 400 according to an embodiment of the present invention;

FIG. 8 is a flowchart illustrating an exemplary MV image system application process according to an embodiment of the present invention;

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

fig. 10 is a schematic diagram of the cone-beam-based helical volume intensity modulated radiotherapy apparatus provided by the present invention generating helical rays around the human body.

Description of the reference numerals：

A stationary frame 100;

a rotating gantry 101;

a cantilever 102;

the microwave system 200: a modulator 201; a magnetron 202; a circulator 203; a gated gun power supply 204; a gated gun 205; an acceleration tube 206; an accelerator tube target 207;

the treatment head 300: a primary collimator 301; a homogenizer 302; an ionization chamber 303; a secondary collimator 304; a double-layer multileaf grating 305; an upper layer individual collimator or an upper layer multi-collimator 305-1; a lower independent collimator or a lower multi-collimator 305-2;

the treatment couch 400: a bottom plate 401, a single-scissor support structure 402, a first driving device 403, a first bearing plate 404, a second bearing plate 405, a second driving device 406, a third bearing plate 407, and a third driving device 408.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

Example one

Referring to fig. 4, the helical volume intensity modulated radiotherapy apparatus based on cone beam provided by the present embodiment includes a stationary gantry 100, a rotating gantry 101, a microwave system 200, a treatment head 300 and a treatment couch 400. The rotating frame 101 is disposed on the fixed frame 100, and the rotating frame 101 can rotate 360 ° relative to the fixed frame 100 along the horizontal B axis in fig. 4 (the rotating frame 101 may be disposed on the fixed frame 100 in a shaft connection manner). The rotating gantry 101 has a substantially cylindrical shape, and a hollow passage is formed in the center thereof, through which (into or out of) the couch 400 carrying the patient passes. The microwave system 200 is disposed on the rotating gantry 101 and is capable of controlling and generating X-rays. The treatment head 300 is provided on the rotating machine 101, and the treatment head 200 can rotate 360 ° along the a axis vertical in fig. 4 with respect to the rotating machine frame 101. Treatment head 300 is capable of modulating X-rays generated by microwave system 200 into a cone-shaped beam. The couch 400 is disposed on one side (shown as the left side in fig. 4) of the rotating gantry 101, and is movable relative to the rotating gantry 101 under the three-dimensional spatial coordinate system X, Y, Z shown in the drawing so that it can enter or exit the rotating gantry 101 via a middle tunnel.

Further, the rotating gantry 101 has a cantilever 102 extending in a direction parallel to the B-axis, and the microwave system 200 is fixedly disposed on the cantilever 102. As shown in connection with fig. 5, the microwave system 200 includes a modulator 201, a magnetron 202, a circulator 203, a gated gun power supply 204, a gated gun 205, an accelerator 206, and an accelerator target 207. Each component is disposed on the rotating gantry 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 with the accelerating tube 206 through the circulator 203. The grid-controlled gun power supply 204 is used for controlling the injection voltage and current of the grid-controlled gun 205, the grid-controlled gun 205 outputs electron beams, and the electron beams are accelerated by the accelerating tube 206 and then impact the accelerating tube target 207 to generate X-ray beams. Wherein the central axis of the X-rays generated by the microwave system 200 coincides with the A-axis, and the B-axis of the A-axis intersects at the isocenter I

As shown in fig. 6, treatment head 300 comprises primary collimator 301, homogenizer 302, ionization chamber 303, secondary collimator 304, and double-layer multileaf grating 305 in this order. Specifically, as shown in connection with fig. 4, treatment head 300 is positioned below accelerator target 207 of microwave system 200, and primary collimator 301 is fixedly nested on cantilever 102. A homogenizer 302 is fixedly disposed on the primary collimator 301, and is used for filtering out low-energy rays to form high-energy rays with uniform distribution. An ionization chamber 303 is fixedly disposed on cantilever 102 below primary collimator 301 for ionizing the inert gas to generate an output electrical signal, which is used to count the dose emitted by the accelerator. A secondary collimator 304 is fixedly arranged on the cantilever 102 and below the ionization chamber 303, and is used for collimating X-rays into a cone beam with a square cross section. Below the secondary collimator 304 is a double-layer multi-leaf grating 305, which double-layer multi-leaf grating 305 is connected to the cantilever 102 shaft, so that the double-layer multi-leaf grating 305 can rotate 360 ° along the vertical a-axis. The device is mainly used for providing conformal walking of an irradiation field during treatment or plan verification and providing support for accurate treatment.

Further, the radiotherapy apparatus also supports a non-uniform (FFF) treatment mode in which the homogenizer 302 can be moved out of the radiation exposure area, the non-uniform radiation is softened with respect to the radiation quality, and the photon flux is increased.

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

Further, the cone-beam based helical volume modulated intensity radiotherapy apparatus comprises a first solenoid valve (not shown) disposed on the rotating gantry 101 or the stationary gantry 100, so that both can be locked by the first solenoid valve. The control system controls the operation of the first electromagnetic valve, when the rotating frame 101 rotates to a preset angle relative to the fixed frame 100 in the treatment process, the rotating frame and the fixed frame are locked by the first electromagnetic valve, the treatment head 300 modulates the cone-beam ray to irradiate the patient on the treatment table 400 until the preset part of the patient is treated, the first electromagnetic valve is disabled, and the rotating frame 101 rotates to the next preset angle relative to the fixed frame 100.

Further, the cone-beam based helical volume modulated intensity radiotherapy apparatus comprises a second solenoid valve (not shown) disposed on the double-layer multi-leaf grating 305 or the cantilever 102, so that the two can be locked by the second solenoid valve. This second solenoid functions similarly to the first solenoid to ensure that the double layer multi-leaf grating 305 does not rotate relative to the cantilever 102 during treatment.

As shown in fig. 7, the treatment couch 400 further includes a base plate 401, a single-blade supporting structure 402, a first driving device 403, a first supporting plate 404, a second supporting plate 405, a second driving device 406, a third supporting plate 407, and a third driving device 408.

Specifically, the single-scissor support structure 402 and the first driving device 403 are both disposed on the base plate 401, and the bottom of the X-shaped single-scissor support structure 402 and the base plate 401 are slidably disposed so that they can perform Z-direction movement (e.g., Z-direction in fig. 4), i.e., lifting and lowering, under the driving of the first driving device 403. The first carrier plate 404 is disposed on the single-scissor support structure 402 such that it can follow the Z-direction movement of the single-scissor support structure 402. The first carrier plate 404 has an X-direction guiding unit (shown as an X-direction in fig. 4, and the X-direction guiding unit in this embodiment is represented as a sliding rail). The second carrier plate 405 and the second driving device 406 are both disposed on the first carrier plate 404, and the lower portion of the second carrier plate 405 has a structure (a slider moving along a guide rail may be adopted in this embodiment) matching with the X-direction guiding unit, so that the second carrier plate 405 moves along the first carrier plate 404 in the X direction under the driving of the second driving device 406. A Y-direction guide unit (shown as a Y-direction in fig. 1, and the Y-direction guide unit in this embodiment is represented as a lead screw) is disposed on the second carrier plate 405. The third loading plate 407 and the third driving device 408 are disposed on the second loading plate 405, and a structure (a screw nut moving along a screw rod may be adopted in this embodiment) matching with the Y-direction guiding unit is disposed at a lower portion of the third loading plate 407, so that the third loading plate 407 moves along the second loading plate 405 in a Y direction under the driving of the third driving device 408.

Example two

In this embodiment, as shown in fig. 4, the cone-beam based helical volume intensity modulated radiotherapy apparatus has a more advanced imaging system configuration, and this part of the components can be selected according to the economic situation. The imaging system comprises an MV imaging system and a CBCT imaging system based on KV level energy X-ray.

The MV imaging system comprises the above-mentioned cone-beam based helical volume modulated intensity radiotherapy apparatus, a MV detector 107 and a beam main shielding assembly 108. The MV detector 107 and the main beamshielding assembly 108 are both arranged on the rotating gantry 101 directly below the therapy head 300 (on the directly opposite side of the therapy head 300), wherein the main beamshielding assembly 108 is located below the MV detector 107.

The CBCT image system based on the KV level energy X-ray comprises a KV beam limiting device 103, a CBCT bulb tube 104, a CBCT high-voltage generator 105 and a KV detector 106. The components of the CBCT imaging system are arranged on a rotating stand 101, wherein a KV beam limiting device 103 and a CBCT bulb 104 are installed together, and a KV detector 106 is arranged on the rotating stand opposite to the CBCT bulb 104. The working principle is that when the CBCT high-voltage generator 105 outputs high voltage to the CBCT bulb tube 104, the CBCT bulb tube 104 can be controlled to generate KV-level X rays with corresponding energy, the X rays transmit the rays to the KV detector 106 through the KV beam limiting device 103, and the central line of the generated X rays and the B axis are intersected with the isocenter I.

Furthermore, the MV imaging system has a variety of applications, and in the case of not being equipped with a CBCT imaging system based on KV-level energy X-rays, the MV imaging system can realize the verification of the patient positioning before treatment by acquiring the projections of the angular positions of the two rotating frames 101. Meanwhile, since the MV imaging system and the treatment head 300 work simultaneously, the MV imaging system can complete Quality Assurance (QA) functions of the radiotherapy apparatus, such as verification of the center position of the radiotherapy apparatus, verification of the walking precision of the double-layer multi-leaf grating 305, and verification of the dose of the treatment field of the radiotherapy apparatus.

Fig. 8 shows a working procedure of the MV imaging system application, in which the MV image detector 107 and the therapy head 300 constitute an image acquisition system, and the image acquisition system firstly acquires projection data, and the acquired data can be used for two-dimensional registration and can also perform the QA function of the radiotherapy apparatus. If the registration function is performed, the data is transmitted to an MV two-dimensional registration system, then projection data and a digital reconstructed radio image (DRR) in a radiotherapy planning system are collected to perform two-dimensional registration, finally the positioning error of the patient is obtained, if the error exceeds the specified positioning deviation requirement, the image system transmits the deviation to a motion control system, the motion control system controls the therapeutic bed 400 to move, the artificial positioning error is eliminated, and finally the patient is accurately subjected to radiotherapy. If the QA function of the radiotherapy device is realized, the acquired projection data are transmitted to the MV QA system, then the system analyzes the projection data to obtain related machine QA or portal related information, such as the flatness, symmetry and dose distribution of dose, and finally a QA analysis report can be printed.

Further, the KV-ray based CBCT system has a variety of applications, such as monitoring of patient position during treatment, verification of patient position before treatment, and the like. FIG. 9 shows an application of the CBCT imaging system in patient positioning verification. The high-voltage generator 105, the CBCT bulb tube 104 and the image detector 106 form an image acquisition system, firstly the projection data sequence acquired by the acquisition system is transmitted to a CBCT workstation for three-dimensional reconstruction, then the reconstructed CBCT volume data and the CT image of the radiotherapy planning system are subjected to three-dimensional volume registration, finally the positioning error of a patient is obtained, if the error exceeds the specified positioning error requirement, the image system transmits the error to a motion control system, the motion control system controls the therapeutic bed 400 to move, the artificial positioning error is eliminated, and finally the patient is accurately subjected to radiotherapy.

Furthermore, the helical volume intensity modulated radiotherapy apparatus based on cone beam provided by the embodiment has a treatment mode based on helical VMAT. The existing VMAT treatment technology is suitable for a smaller tumor target area and can complete irradiation treatment at one time. This technology is also relatively mature technology, and can be considered as a subset of spiral VMAT in summary, and the device also supports VMAT treatment modalities, because of the relatively mature technology, it is not repeated here. Compared with the traditional VMAT treatment mode, the spiral VMAT treatment mode is suitable for treating large tumors, and has higher efficiency, smoother dose distribution and higher conformality, so that the dose distribution is more accurate. The helical VMAT can complete treatment of all lesions after one patient setup without the need for traditional techniques to switch to multi-center treatment. After the traditional treatment mode switching center is repositioned, the method belongs to a new treatment, and operations such as repositioning, verification and the like are needed, so that the spiral VMAT is relatively less in time consumption. In particular, the treatment mode is safer, because the whole process of the treatment process can be automated, the manual intervention of the intermediate process is not needed, and the possibility of human errors is reduced. The treatment of the whole target area is realized through the moving bed with uniform speed in the whole process, and the mode can ensure the modulation accuracy of the dosage intensity through movement and ensure that the dosage conformality of the target area is better.

Further, in connection with fig. 10, to treat a large tumor, a spiral VMAT treatment technique is introduced. The key to realizing the treatment mode of the spiral VMAT is to control the movement of each moving part of the accelerator and the X-ray beam output so as to achieve the coordinated and accurate work of each part. The parameters of the components to be controlled include the speed of the rotating gantry 101, the number of machine hops of the radiotherapy device, the speed of movement of the leaves of the double-layer multi-leaf grating 305, and the speed of movement of the couch 400. The parameter constraints for 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, y respectively represent the rotational speed of the rotating gantry 101, the machine jump number of the radiotherapy apparatus (dose monitoring is shown in units of machine jump number MU), the motion displacement of the double-layer multi-leaf grating 305, and the motion displacement of the treatment couch 400. (d θ/dt)_max,(dMU/dt)_max,(dx/dt)_max,(dy/dt)_maxRepresenting the maximum speed of the rotating gantry 101, the maximum dose rate of the accelerator, the maximum speed of the double-layered multi-leaf grating 305, and the maximum speed of the couch, respectively. When executing the patient treatment plan, each device can not exceed the maximum speed of the respective machine, otherwise, the linkage system of the accelerator reports the linkage and gives corresponding prompt information and a method for removing the linkage on a linkage interface. The rotating gantry 101 of the accelerator is designed to support a speed of 6 revolutions per minute, and if the speed of one revolution per minute is used during treatment, the operating speed of the gantry may be reduced for safety during treatment, and the high-speed gantry rotation mode is more applied to imaging and verification functions.

Then the maximum speed of the frame motion at this time is (d θ/dt)_max6deg/s, set by the maximum speed of the double-layer multileaf grating 305 (dx/dt)_maxA displacement of 1cm for the maximum two-layer multi-leaf grating 305 per degree of rotation of the rotating gantry 101 can be obtained, i.e.:

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

likewise by setting the accelerator maximum dose rate (dMU/dt)_maxIt can be obtained that the number of machine hops per one degree of rotation of the rotating gantry 101 is about 2.2MU, 800MU/min, i.e.:

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

meanwhile, the maximum dosage rate of the accelerator in the embodiment is up to 1200 MU/min.

Likewise by setting the maximum speed (dy/dt) for couch 400_maxA maximum couch 400 displacement of 1cm/s per one degree of rotation of the rotating gantry 101 can be obtained, 6cm/s, i.e.:

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

in order to better ensure the precision of treatment during the treatment process, the movement speed of the treatment couch 400 of the therapeutic device in this embodiment is set as a parameter that is not changeable. In summary, in the process of implementing the spiral VMAT, the grating position of the treatment head 300 changes in real time every time the rotating frame 101 rotates by one degree to conform to the shape of the treatment field target area, and the dose rate is also changing, so as to ensure the accuracy of the radiation treatment dose, and the treatment couch 400 runs at a constant speed, so that when the treatment couch 400 covers the whole tumor region, the treatment of the patient is completed.

Further, the radiotherapy apparatus provides a real-time dose statistics function, when the treatment plan is deviated in execution, within the allowable deviation range of the deflection and the dose of the rotating frame 101, the bgm (beam Generator module) system of the radiotherapy apparatus can adjust the dose rate to compensate, and when the dose is insufficient, the dose rate is increased, but the dose rate cannot exceed the dose rate range supported by the machine, otherwise, the system reports the linkage of the dose insufficiency. When the dosage is larger, the dosage rate is reduced, the same dosage rate cannot exceed the dosage rate range supported by the machine, otherwise, the system reports the linkage of the dosage excess.

Further, when a deviation in the treatment plan occurs during the delivery, the bgm (beam Generator module) system of the radiotherapy apparatus can adjust the speed of the rotating gantry 101 to compensate for the deviation in the deflection of the rotating gantry 101 and the dose, and reduce the speed of the rotating gantry 101 when the dose is insufficient. If the dose is too large, the speed of the rotating gantry 101 is increased, but the rotation speed cannot exceed the maximum rotation speed supported by the machine itself, otherwise the system will report a chain of dose overshoots.

Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not limitative. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. Spiral volume intensity modulated radiotherapy device based on conical beam, its characterized in that includes:

a stationary frame (100);

a rotating gantry (101) arranged on the stationary gantry (100), the rotating gantry (101) having a central passage, the rotating gantry (101) being capable of rotating 360 ° along a horizontal B-axis relative to the stationary gantry (100);

a microwave system (200) arranged on the rotating gantry (101) for generating radiation;

a treatment head (300) arranged on the rotating gantry (101) for modulating the radiation generated by the microwave system (200) into a cone-shaped beam, the treatment head (300) being rotatable 360 ° along a vertical a-axis relative to the rotating gantry (101);

a couch (400) arranged to one side of the rotating gantry (101), the couch (400) being movable relative to the rotating gantry (101) under a three-dimensional spatial coordinate system X, Y, Z such that it can enter or exit the rotating gantry (101) via the central passage.

2. The apparatus of claim 1, comprising:

a first solenoid valve provided on the rotating gantry (101) or the stationary gantry (100) so that both can be locked by the first solenoid valve.

3. The cone-beam based helical volume intensity modulated radiation therapy apparatus according to claim 1, characterized in that the rotating gantry (101) has a cantilever (102) extending parallel to the B-axis direction; the microwave system (200) comprises a modulator (201), a magnetron (202), a circulator (203), a grid-controlled gun power supply (204), a grid-controlled gun (205), an accelerating tube (206) and an accelerating tube target (207); the modulation modulator (201) controls the magnetron (202), the magnetron (202) is connected with the accelerating tube (206) through a circulator (203), the grid-controlled gun power supply (204) is used for controlling injection voltage and current of the grid-controlled gun (205) so that the grid-controlled gun (205) outputs electron beams, the accelerating tube (206) accelerates the electron beams and then enables the electron beams to impact the accelerating tube target (207) to generate X-ray beams, a central axis of the X-ray generated by the microwave system (200) is coincident with the axis A, and the axis A and the axis B are intersected at an isocenter I.

4. The cone-beam based helical volume modulated intensity radiotherapy apparatus of claim 3, wherein the treatment head (300) and the rotating gantry (101) are connected by a cantilever (102) and located below the accelerating tube target (207), the treatment head (300) comprising:

a primary collimator (301) fixedly nested on the cantilever (102);

an ionization chamber (303) fixedly disposed on the cantilever (102) and below the primary collimator (301) for ionizing an 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);

a double-layer multileaf grating (305) located below the secondary collimator (304), the double-layer multileaf grating (305) being connected to the cantilever (102) shaft such that the double-layer multileaf grating (305) can be rotated 360 ° along the vertical a-axis.

5. The cone-beam based helical volume modulated intensity radiotherapy apparatus of claim 4, wherein the treatment head (300) comprises:

a homogenizer (302) fixedly arranged on the primary collimator (301) and capable of filtering low-energy X-rays to form a uniformly distributed high-energy X-rays.

6. The cone-beam based helical volume intensity modulated radiotherapy apparatus of claim 4, characterized in that the double-layer multileaf grating (305) comprises:

an upper layer independent collimator or an upper layer multi-element collimator (305-1) and a lower layer multi-element collimator (305-2) which are fixedly connected with each other; or

A lower independent collimator or a lower multi-collimator (305-2) and an upper multi-collimator (305-1) which are fixedly connected with each other.

7. The apparatus of claim 4, comprising:

a second solenoid valve provided on the double-layer multi-leaf grating (305) or the cantilever (102) so that both can be locked by the second solenoid valve.

8. The cone-beam based helical volume modulated intensity radiotherapy apparatus of claim 4, wherein the treatment couch (400) comprises:

a bottom plate (401);

a single-scissor supporting structure (402) arranged on the bottom plate (401) and a first driving device (403) used for driving the single-scissor supporting structure (402) to complete Z-direction movement;

a first carrier plate (404) having an X-direction guide unit disposed on the single-scissor support structure (402);

the second bearing plate (405) is arranged on the first bearing plate (404) and can move along the X-direction guide unit, and the second driving device (406) is used for driving the second bearing plate (405) to move along the X-direction guide unit, wherein the second bearing plate (405) is provided with a Y-direction guide unit;

a third bearing plate (407) which is arranged on the second bearing plate (405) and can move along the Y-direction guide unit, and a third driving device (408) which is used for driving the third bearing plate (407) to move along the Y-direction guide unit.

9. The cone-beam based helical volume intensity modulated radiation therapy device according to claim 8, characterized in that the rotation speed of the rotating gantry (101), the machine hop count of the radiation therapy device, the vane movement speed of the double-layer multi-vane grating (305) and the movement speed of the treatment couch (400) satisfy the following conditions:

Δθ/Δt≤(dθ/dt)_max；

ΔMU/Δt≤(dMU/dt)_max；

Δx/Δt≤(dx/dt)_max；

Δy/Δt≤(dy/dt)_max；

wherein theta, MU, x and y respectively represent the rotation speed of the rotating frame (101), the machine jump number of the radiotherapy device, the motion displacement of the double-layer multi-leaf grating (305) and the motion displacement of the treatment couch (400);

(dθ/dt)_max、(dMU/dt)_max、(dx/dt)_max、(dy/dt)_maxrepresenting the maximum speed of the rotating gantry (101), the maximum dose rate of the accelerator, the maximum speed of the double-layered multi-leaf grating (305) and the maximum speed of the couch (400), respectively.

10. Image system of spiral volume accentuation based on toper bundle characterized in that includes:

the cone-beam based helical volume modulated intensity radiotherapy apparatus and MV imaging system of any one of claims 1 to 9;

the MV video system comprises:

an MV detector (107) arranged on the rotating gantry (101) for acquiring X-rays penetrating the treatment couch (400);

a main beam shielding assembly (108) disposed on the rotating gantry (101) and below the MV detector (107);

the MV detector (107) and the main beam shielding assembly (108) are positioned on opposite sides of the therapy head (300).

11. The cone-beam based helical volume-modulated imaging system of claim 10, further comprising a KV-level energy X-ray based CBCT imaging system, the CBCT imaging system comprising:

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

the CBCT bulb tube (104) is arranged on the rotating rack (101) and can generate KV-level X-rays with corresponding energy under the control of the CBCT high-voltage generator (105);

the KV beam limiting device (103) is arranged on the rotating rack (101) and is positioned at the front end of the CBCT bulb tube (104);

the KV detector (106) is arranged on the rotating rack (101) and is positioned on the right opposite side of the CBCT bulb tube (104);

the central line of KV level X-ray generated by the CBCT bulb tube (104) and the B axis intersect at an isocenter I.