A compact electron linear accelerator for an x-ray intratreatment radiotherapy device

Abstract

This invention provides a compact linear electron accelerator for X-ray intraoperative radiotherapy equipment, comprising a klystron module, a beam acceleration module, a microwave transmission module, a conversion target module, and a control module. The electron beam generated by the klystron module is transmitted to the conversion target module via the beam acceleration module to generate X-rays. The generated microwave power is injected into the beam acceleration module via the microwave transmission module to provide microwave power. The control module controls the parameters of each module. The klystron module includes an electron gun, an input cavity, an intermediate cavity, an output cavity, and a beam controller. The input cavity is connected to an excitation source to provide microwave input, and the output cavity is connected to the microwave transmission module to provide microwave output. This linear electron accelerator uses the klystron simultaneously as a microwave power source and an electron generator, requiring only one electron gun. By using microwaves to accelerate electrons, the 50kV high voltage of the electron gun can be reduced to below 10kV, thus saving on the cost of the electron gun.

Description

Technical Field

[0001] This invention belongs to the field of medical electron accelerators, and particularly relates to a compact electron linear accelerator for use in X-ray intraoperative radiotherapy equipment. Background Technology

[0002] Treatment methods for tumors include surgery, radiotherapy, chemotherapy, hormone therapy, and targeted therapy. In clinical treatment principles, surgery has the highest priority. However, during surgery, incomplete removal of the tumor or residual cancer cells in the tumor bed can lead to tumor recurrence. To reduce the recurrence rate, a combination of surgery and radiotherapy, known as intraoperative radiotherapy (IRT), has been developed. IRT is defined as radiation therapy performed during surgery. Typically, after surgical removal of the tumor, a single high-dose irradiation is administered to the tumor bed and unresectable areas to inhibit tumor growth or prevent recurrence. Internationally, IRT equipment technology has developed rapidly and is highly mature, primarily in Europe and the United States. It is widely used for breast cancer, pancreatic cancer, gastrointestinal tumors, brain tumors, head and neck tumors, skin cancer, and spinal metastases, applicable to a wide range of cases and a large patient population. Typical electron beam IRT equipment is represented by the United States and Italy, including Mobetron, LIAC, and Novac-7. X-ray IRT equipment includes Zeiss's Intrabeam from Germany and iCAD's Xoft Axxent from the United States. However, the progress of intraoperative radiotherapy technology in China has been slow. Currently, there is a mobile electron beam intraoperative radiotherapy system developed by Hunan Huachuang Medical Technology Co., Ltd. in China, but there is no prototype of X-ray intraoperative radiotherapy equipment yet.

[0003] The German Zeiss Intrabeam system uses a 50kV high voltage to accelerate electrons to 50keV, which places higher demands on the safety and stability of the equipment. The invention patent application "A compact electron linear accelerator for X-ray intraoperative radiotherapy equipment" (application number 202510006880.1, hereinafter referred to as prior art 1) uses two electron guns, and its system structure is relatively complex, which does not have an advantage in terms of equipment cost and energy consumption. Summary of the Invention

[0004] The purpose of this invention is to provide a compact electronic linear accelerator for X-ray intraoperative radiotherapy equipment, which reduces the high voltage required by the equipment to improve its safety and stability.

[0005] To achieve the above objectives, the present invention provides a compact electron linear accelerator for X-ray intraoperative radiotherapy equipment, comprising a klystron module, a beam acceleration module, a microwave transmission module, a conversion target module, and a control module; the electron beam generated by the klystron module is transmitted to the conversion target module after passing through the beam acceleration module to generate X-rays, and the microwave power generated by the klystron module is injected into the beam acceleration module through the microwave transmission module to provide microwave power; the control module is configured to control the parameters of the klystron module, the microwave transmission module, the beam acceleration module, and the conversion target module; wherein, the klystron module includes an electron gun, an input cavity, an intermediate cavity, an output cavity, and a beam controller connected in sequence, the input cavity is connected to an excitation source to provide microwave input, and the output cavity is connected to the microwave transmission module to provide microwave output.

[0006] The high voltage of the electron gun is within 10kV.

[0007] The beam controller is circular or elongated in shape.

[0008] The beam controller is equipped with multiple circular holes of different sizes for controlling the beam intensity.

[0009] The diameters of the multiple circular holes of different sizes on the beam controller range from 0.5 to 10 mm.

[0010] The beam acceleration module includes a first cavity, a coupling cavity, a second cavity, and a drift tube connected in sequence, as well as a solenoid sleeved on the drift tube. The first cavity is connected to the beam controller of the klystron module to receive the electron beam.

[0011] The microwave transmission module includes an isolator and a directional coupler connected in sequence. The directional coupler is connected to the second cavity of the beam acceleration module and is used to provide microwave energy to the beam acceleration module.

[0012] A phase shifter is provided between the isolator and the directional coupler.

[0013] The downstream of the conversion target module is connected to an applicator to provide X-rays to the applicator.

[0014] The conversion target module is connected to the control system via a dose detector.

[0015] This invention uses a klystron as both a microwave power source and an electron generator, requiring only one electron gun. By using the microwaves from the electron gun to accelerate electrons, the 50kV high voltage of the electron gun used in existing equipment can be reduced to below 10kV, thus saving the cost of the electron gun. Attached Figure Description

[0016] Figure 1This is an overall structural diagram of a compact electron linear accelerator for X-ray intraoperative radiotherapy equipment according to the present invention;

[0017] Figure 2 This is a cross-sectional view of a beam controller for a compact electronic linear accelerator used in X-ray intraoperative radiotherapy equipment according to the present invention. Detailed Implementation

[0018] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0019] like Figure 1 As shown, this invention provides a compact electron linear accelerator for X-ray intraoperative radiotherapy equipment, comprising a klystron module 10, a beam acceleration module 20, a microwave transmission module 30, a conversion target module 40, and a control module 50. The klystron module 10, the beam acceleration module 20, and the conversion target module 40 are arranged sequentially in the beam propagation direction, such that the electron beam generated by the klystron module 10 is transmitted to the conversion target module 40 after passing through the beam acceleration module 20 to generate X-rays.

[0020] The klystron module 10 includes an electron gun 11, an input cavity 12, an intermediate cavity 13, an output cavity 14, and a beam controller 15 connected in sequence. The input cavity 12 is connected to an excitation source 16 so that the excitation source 16 provides microwave input. The output cavity 14 is connected to the microwave transmission module 30 so that the output cavity 14 provides microwave output. The microwave transmission module 30 is connected to the beam acceleration module 20 to provide microwave energy to it.

[0021] Input cavity 12 receives the microwave signal from an external excitation source and establishes a high-frequency electric field at its gap. As the electron beam passes through, it is velocity-modulated by this electric field, initiating density variations. Intermediate cavity 13, located between the input and output, induces a stronger high-frequency field as the initially modulated electron beam passes through, further modulating the beam. Output cavity 14, located at the end of the modulation system, effectively slows down the highly concentrated electron clusters (agglomerates), converting kinetic energy into microwave energy and outputting high-power microwaves. Beam controller 15 controls the beam current intensity. Excitation source 16 provides the input cavity with the raw microwave signal to be amplified.

[0022] like Figure 2 As shown, the beam controller 15 is connected to the beam acceleration module 20. The beam controller 15 is circular or elongated. The beam controller 15 has multiple circular holes of different sizes for controlling the beam intensity. The diameter of the multiple circular holes of different sizes on the beam controller 15 can range from 0.5 to 10 mm.

[0023] Thus, the electron beam generated by the klystron module 10 is transmitted to the conversion target module 40 after passing through the beam acceleration module 20 to generate X-rays, and the microwave power generated by the klystron module 10 is injected into the beam acceleration module 20 through the microwave transmission module 30 to provide microwave power; the control module 50 is configured to control the parameters of the klystron module 10, the microwave transmission module 30, the beam acceleration module 20, and the conversion target module 40.

[0024] The beam acceleration module 20 includes a first cavity 21, a coupling cavity 22, a second cavity 23, and a drift tube 24 connected in sequence, as well as a solenoid 25 sleeved on the drift tube 24. The first cavity 21 is connected to the beam controller 15 of the klystron module 10 to receive the electron beam. Thus, the electrons required in the beam acceleration module 20 are directly provided by the klystron module 10, and the beam acceleration module 20 realizes the acceleration of electrons using X-band microwaves. Preferably, the cavity wall of the coupling cavity 22 is made of a corrugated tube, and its length is adjustable. Therefore, the compact electron linear accelerator for X-ray intraoperative radiotherapy equipment of the present invention can adjust the cavity spacing between the first cavity 21 and the second cavity 23 by adjusting the length of the coupling cavity 22, thereby changing the phase difference between the two cavities. This allows the first cavity 21 to accelerate electrons, while the second cavity 23 performs electron beam energy spectrum optimization, resulting in a better energy spectrum optimization effect. Furthermore, the addition of the solenoid 25 on the drift tube 24 provides a focusing effect, ultimately resulting in a higher number of electrons and a higher capture rate at the exit of the beam acceleration module 20.

[0025] Existing technology uses a 50kV high voltage to directly accelerate electrons to 50keV, while the present invention uses microwaves to establish an electromagnetic field in the beam acceleration module 20 to further accelerate electrons. Therefore, the initial electron beam energy is within 10keV, and the high voltage of the electron gun 11 is within 10kV.

[0026] The microwave transmission module 30 includes an isolator 31, a phase shifter 32 and a directional coupler 33 connected in sequence. The directional coupler 33 is connected to the second cavity 23 of the beam acceleration module 20 and is used to provide microwave energy to the beam acceleration module 20.

[0027] Therefore, a phase shifter 32 is provided between the isolator 31 and the directional coupler 33 in the microwave transmission module 30, thereby adjusting the phase of the microwave field output by the microwave transmission module 30 so that the beam in the beam acceleration module 20 is matched with the microwave field of the required phase during the acceleration process. The matching condition for the beam during the acceleration process is that the phase difference between the microwave injected into the second cavity and that of the first cavity is 90 degrees.

[0028] Isolator 31 is used to achieve unidirectional microwave transmission, absorb cavity reflected waves, isolate load reflection interference, protect the microwave transmitter, and stabilize microwave output. Directional coupler 33 is used to feed microwave power from the power source into the accelerating cavity, and can monitor the forward microwave power incident on the accelerating cavity and the reverse power reflected by the cavity in real time, providing a quantitative feedback signal of the cavity resonance state to the control system 50.

[0029] The downstream of the conversion target module 40 is connected to the applicator 60 to provide X-rays to the applicator 60. The conversion target module 40 is connected to the control system via the dose detector 51.

[0030] Control module 50 is configured to acquire and output the following parameters:

[0031] 1) Directional coupler 33: Collects signals of incident microwave power and reflected microwave power, and then monitors the output power of the microwave power source and the fault status of the cavity microwave standing wave / reflection.

[0032] 2) Radiation dose monitoring input: Acquire two independent real-time X-ray dose rate and cumulative dose sampling signals from two dose detectors 51, collect X-ray dose data emitted from the conversion target module 40 respectively, and provide closed-loop feedback of the actual output dose.

[0033] 3) Excitation source in the klystron: The control module 50 outputs power adjustment and signal start / stop control signals to it to regulate the microwave output power.

[0034] 4) Electron gun 11 in klystron module 10: Control module 50 outputs filament power and high voltage pulse trigger control signals to control the start and stop of electron beam emission.

[0035] Experimental Result 1: A Compact Electron Linear Accelerator for Intraoperative X-ray Radiotherapy Equipment

[0036] In this experiment, the specific structure of the compact electron linear accelerator used in X-ray intraoperative radiotherapy equipment is consistent with that of the compact electron linear accelerator used in X-ray intraoperative radiotherapy equipment described above.

[0037] When the ratio of the electric field amplitude of the first cavity to that of the second cavity is 1:0.06, the diameter of the circular aperture is 0.5 mm, the corresponding peak beam current intensity is 2 μA, the final output average energy is 43.4 eV, the energy of the highest particle number in the energy spectrum is 51.9 keV, and the electron capture rate reaches 40.8%, thus meeting the requirements of X-ray intraoperative radiotherapy equipment.

[0038] Experimental Result 2: A Compact Electron Linear Accelerator for X-ray Intraoperative Radiotherapy Equipment

[0039] In this experiment, the specific structure of the compact electron linear accelerator used in X-ray intraoperative radiotherapy equipment is consistent with that of the compact electron linear accelerator used in X-ray intraoperative radiotherapy equipment described above.

[0040] When the ratio of the electric field amplitude of the first cavity to that of the second cavity is 1:0.08, the diameter of the circular aperture is 3mm, the corresponding peak beam current intensity is 40μA, the final output average energy is 44.1keV, the energy of the highest particle number in the energy spectrum is 50.9keV, and the electron capture rate reaches 40.60%, thus meeting the requirements of X-ray intraoperative radiotherapy equipment.

[0041] Experimental Result 3: A Compact Electron Linear Accelerator for Intraoperative X-ray Radiotherapy Equipment

[0042] In this experiment, the specific structure of the compact electron linear accelerator used in X-ray intraoperative radiotherapy equipment is consistent with that of the compact electron linear accelerator used in X-ray intraoperative radiotherapy equipment described above.

[0043] When the ratio of the electric field amplitude of the first cavity to that of the second cavity is 1:0.11, the diameter of the circular aperture is 10 mm, the corresponding peak beam current intensity is 450 μA, the final output average energy is 43.3 keV, the energy of the highest particle number in the energy spectrum is 50.4 keV, and the electron capture rate reaches 40.24%, which meets the requirements of X-ray intraoperative radiotherapy equipment.

[0044] Comparative experiment: Using the scheme in existing technology 1, the final output average energy is 44keV, the energy of the highest number of particles in the energy spectrum is 50.2keV, and the electron capture rate is only 25%.

[0045] In summary, comparing the experimental results of this invention with those of the comparative experiment, the technical solution of this invention achieves a capture rate of over 40% while saving the cost of an electron gun. Compared to the 25% of the comparative experiment, the capture rate percentage is increased by at least 62%.

[0046] This invention uses a klystron as both a microwave power source and an electron generator, requiring only one electron gun. By using the microwaves from the electron gun to accelerate electrons, the 50kV high voltage of the electron gun used in existing equipment can be reduced to below 10kV, thus saving the cost of the electron gun.

[0047] 1. The difference between the klystron and the traditional klystron is that the collector is not placed at the end of the klystron structure. Instead, electrons are directly extracted. Using the new klystron, the electron gun of the accelerating tube can be replaced to provide an electron beam to the accelerating tube while providing microwave power. This method greatly reduces the complexity of the system. The klystron can not only provide microwave energy to the accelerating tube, but also replace the electron gun to provide an electron beam.

[0048] 2. By using X-band microwaves to accelerate electrons, the existing 50kV high voltage of intraoperative X-ray radiotherapy equipment can be reduced to below 10kV while ensuring that the technical specifications are met, thereby improving the stability and safety of the equipment.

[0049] 3. A beam controller is installed after the output cavity from the klystron where electrons are drawn out. The beam controller is a disc or strip with circular holes of different diameters, which can control the beam intensity drawn out from the klystron to obtain electron beams with different intensities.

[0050] 4. By installing a phase shifter in the isolator and directional coupler, the phase of the microwave injected from the klystron into the accelerating tube can be adjusted, ultimately matching the electron beam and microwave phase to the desired phase.

[0051] 5. By connecting different applicators after the conversion target, different X-ray dose distributions can be formed for different tumors.

[0052] 6. By adopting the technical solution of the present invention, the capture rate is still above 40% while saving the cost of an electron gun. Compared with the prior art 1, the capture rate percentage is increased by at least 60.96%.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A compact electron linear accelerator for use in X-ray intraoperative radiotherapy equipment, characterized in that, It includes a klystron module, a beam acceleration module, a microwave transmission module, a conversion target module, and a control module. The electron beam generated by the klystron module is transmitted to the conversion target module after passing through the beam acceleration module to generate X-rays. The microwave power generated by the klystron module is injected into the beam acceleration module through the microwave transmission module to provide microwave power. The control module is configured to control the parameters of the klystron module, the microwave transmission module, the beam acceleration module, and the conversion target module. The klystron module includes an electron gun, an input cavity, an intermediate cavity, an output cavity, and a beam controller connected in sequence. The input cavity is connected to an excitation source so that the excitation source provides microwave input, and the output cavity is connected to the microwave transmission module so that the output cavity provides microwave output.

2. The electron linear accelerator according to claim 1, characterized in that, The high voltage of the electron gun is within 10kV.

3. The electron linear accelerator according to claim 1, characterized in that, The beam controller is circular or elongated in shape.

4. The electron linear accelerator according to claim 3, characterized in that, The beam controller is equipped with multiple circular holes of different sizes for controlling the beam intensity.

5. The electron linear accelerator according to claim 4, characterized in that, The diameters of the multiple circular holes of different sizes on the beam controller range from 0.5 to 10 mm.

6. The electron linear accelerator according to claim 1, characterized in that, The beam acceleration module includes a first cavity, a coupling cavity, a second cavity, and a drift tube connected in sequence, as well as a solenoid sleeved on the drift tube. The first cavity is connected to the beam controller of the klystron module to receive the electron beam.

7. The electron linear accelerator according to claim 6, characterized in that, The microwave transmission module includes an isolator and a directional coupler connected in sequence. The directional coupler is connected to the second cavity of the beam acceleration module and is used to provide microwave energy to the beam acceleration module.

8. The electron linear accelerator according to claim 1, characterized in that, A phase shifter is provided between the isolator and the directional coupler.

9. The electron linear accelerator according to claim 1, characterized in that, The downstream of the conversion target module is connected to an applicator to provide X-rays to the applicator.

10. The electron linear accelerator according to claim 1, characterized in that, The conversion target module is connected to the control system via a dose detector.

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