A medical accelerator and a dose monitoring method thereof based on electron beam extraction process

Abstract

The present invention relates to the technical field of medical accelerators, and discloses a medical accelerator, wherein an accelerating tube, a beam pipe, and a beam needle share a central axis and are connected to form a straight channel for electron beams to be transmitted in the straight channel; a beam extraction tube is connected to the side of the beam pipe, and a first electron beam is transmitted in the beam extraction tube; a deflection magnetic field generating device is arranged on the periphery of the beam pipe, and periodically causes the electron beam to change the transmission direction and output from the beam extraction tube. A dose monitoring method for a medical accelerator is also disclosed, wherein the doses of the first electron beam and the second electron beam are tested simultaneously before treatment to establish a related numerical relationship, and the dose of the second electron beam is monitored by testing the dose of the first electron beam during treatment. The present invention "extracts" a very small part of the electron beam for synchronous testing through the beam extraction tube and the deflection magnetic field generating device, and the steps for measuring the dose are simple and convenient, and the treatment process is not affected, and online dose monitoring is achieved, and the method is feasible and the results are reliable.

Description

Technical Field

[0001] The invention relates to the technical field of medical accelerators, and in particular to a medical accelerator and a dose monitoring method thereof based on an electron beam extraction process. Background Art

[0002] According to the requirements of the national standard GB9706.5-2008, a dose monitoring system must be included in the medical electron linear accelerator. The dose monitoring system used in traditional medical accelerators consists of an ionization chamber detector and its auxiliary circuits. The ionization chamber is located within the radiation system and is installed between the uniform filter or scattering foil and the secondary collimator of the photon line. It is composed of several pole pieces, two pairs of which are used to monitor the uniformity of the two perpendicular directions in the radiation field, one piece is used to monitor the energy change of the radiation, and two pieces are used to detect the absorbed dose of the radiation. Most dose monitoring systems of traditional medical accelerators use flat-plate ionization chambers, the size of which should cover the entire treatment field, and a few use finger-shaped ionization chambers. The function of the dose monitoring system is to monitor the dose rate, integrated dose, and symmetry and flatness of the X-ray and electron beam.

[0003] The medical accelerator of the present invention directly utilizes electron beams to treat tumors. The entire process from the electron beam leaving the accelerating tube to reaching the tumor is transmitted in a thin tube (with an inner diameter of less than 5 mm) and cannot directly pass through the ionization chamber. Therefore, the ionization chamber is not suitable for this device. Currently, there is no relevant dose monitoring method at home and abroad to online test the therapeutic dose of such a small electron beam. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a medical accelerator with a small-field electron beam, and a dose monitoring method of the medical accelerator with a small-field electron beam capable of online monitoring during a treatment process.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The invention provides a medical accelerator, comprising an electron gun control power supply, an electron gun, an accelerating tube, a magnetron, a modulator, a beam pipe and a beam needle; the electron gun control power supply is used to control the electron gun injection voltage; the electron gun is used to output an electron beam, the accelerating tube is used to accelerate the electron beam output by the electron gun and then output it through the beam needle; the modulator is used to control the magnetron; the magnetron is connected to the accelerating tube through a waveguide chain; the rear end of the beam pipe is fixedly connected to the front end center of the accelerating tube, and the front end of the beam pipe is connected to the beam needle; the accelerating tube, the beam pipe and the beam needle have a common central axis and are connected to form a straight line channel for the electron beam to be transmitted in the straight line channel; the side of the beam pipe is connected to a beam extraction tube, a first electron beam is transmitted in the beam extraction tube, a deflection magnetic field generating device is arranged on the periphery of the beam pipe, and periodically causes the electron beam to change the transmission direction and output from the beam extraction tube to form the first electron beam; the electron beam output by the beam needle is a second electron beam.

[0007] Preferably, the outlet ends of the beam needle and the beam outlet tube are both sealed ends.

[0008] Preferably, the magnetic field direction of the deflection magnetic field generating device is perpendicular to the plane formed by the beam extraction tube and the beam pipeline. When the beam extraction tube is located to the right of the accelerating tube, the magnetic field direction of the deflection magnetic field points from the distal end to the proximal end.

[0009] Preferably, a first connection portion is provided at the front end of the beam pipe, and a second connection portion is provided at the inlet end of the beam needle, and the first connection portion and the second connection portion are detachably connected.

[0010] The present invention also provides a dose monitoring method for a medical accelerator according to any of the above technical solutions, comprising the following steps:

[0011] S1: the deflection magnetic field generating device works within a time Δt, causing the electron beam to change its transmission direction and be output from the beam extraction tube to form the first electron beam;

[0012] S2: the first electron beam is emitted into the first dose probe, and the first dose probe collects a first signal;

[0013] S3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H of the first electron beam. a ;

[0014] S4: The first data processing system performs a dose H of the first electron beam on the first electron beam. a The data is further processed to obtain the dose H of the second electron beam. b .

[0015] Preferably, the dose rate H of the first electron beam in step S4 is a The dose rate H of the second electron beam b There is a linear numerical relationship: H b =KH a .

[0016] Preferably, the steps of determining K are as follows:

[0017] P1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the beam outlet tube to form the first electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, wherein n is a positive integer;

[0018] P2: the first electron beam is injected into a first dose probe, and the first dose probe collects a first signal; the second electron beam is injected into a second dose probe, and the second dose probe collects a second signal;

[0019] P3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H21 of the second electron beam;

[0020] P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate H2(H22,H23,H24,H2 i ,┉);

[0021] P5: Set the dose rate of the first electron beam H1 (H11, H12, H13, H14, H1 i ,┉) and the dose rate H2(H21,H22,H23,H24,H2 i ,┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K is obtained.

[0022] Preferably, before step S1, the method further includes: placing the head end of the dose probe opposite to the outlet of the beam extraction tube and on the same central axis.

[0023] Preferably, the dose probe and the data processing system perform data transmission via wireless or wired mode. The wireless mode is one of WIFI, cellular network, microwave communication, and Bluetooth. The wired mode is one of optical fiber transmission, twisted pair transmission, and broadband co-cable transmission.

[0024] The present invention also provides a medical accelerator, comprising an electron gun control power supply, an electron gun, an accelerating tube, a magnetron, a modulator, a beam pipe and a beam needle; the electron gun control power supply is used to control the injection voltage of the electron gun; the electron gun is used to output an electron beam, and the accelerating tube is used to accelerate the electron beam output by the electron gun and output it through the beam needle; the modulator is used to control the magnetron; the magnetron is connected to the accelerating tube through a waveguide chain; the rear end of the beam pipe is fixedly connected to the front end center of the accelerating tube, and the front end of the beam pipe is connected to the beam needle; the accelerating tube, the beam pipe and the beam needle share a central axis and are connected to form a A straight channel is provided for the electron beam to be transmitted in the straight channel; a first beam lead-out tube and a second beam lead-out tube are connected to the side of the beam pipe, the first beam lead-out tube and the second beam lead-out tube are symmetrically arranged with respect to the beam pipe, the first electron beam is transmitted in the first beam lead-out tube, and the third electron beam is transmitted in the second beam lead-out tube; a deflection magnetic field generating device is arranged at the periphery of the beam pipe, which periodically causes the electron beam to change the transmission direction and output from the first beam lead-out tube to form the first electron beam, and periodically causes the electron beam to change the transmission direction and output from the second beam lead-out tube to form the third electron beam; the electron beam output by the beam needle is the second electron beam.

[0025] Preferably, the outlet ends of the beam needle and the beam outlet tube are both sealed ends.

[0026] Preferably, the magnetic field direction of the deflection magnetic field generating device is perpendicular to the plane formed by the first beam extraction tube and the beam pipe. When the first electron beam is required to be output from the first beam extraction tube, the magnetic field direction of the deflection magnetic field is from the distal end to the proximal end. When the third electron beam is required to be output from the second beam extraction tube, the magnetic field direction of the deflection magnetic field is from the proximal end to the distal end.

[0027] The present invention also provides a dose monitoring method for monitoring the medical accelerator described in any one of the above technical solutions, characterized in that it comprises the following steps:

[0028] S1: the deflection magnetic field generating device works within a time Δt, causing the electron beam to change its transmission direction and be output from the first beam outlet tube to form the first electron beam;

[0029] S2: the first electron beam is emitted into a first dose probe, and the first dose probe collects a first signal;

[0030] S3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H of the first electron beam. a ;

[0031] S4: The first data processing system performs a dose H of the first electron beam on the first electron beam. a The data is further processed to obtain the dose H of the second electron beam. b .

[0032] S5: the deflection magnetic field generating device operates within a time Δt, so that the electron beam changes its transmission direction and is output from the second beam outlet tube to form the third electron beam;

[0033] S6: the third electron beam is injected into a third dose probe, and the third dose probe collects a third signal;

[0034] S7: The third dose probe completes collecting the third signal, and the third data processing system processes the third signal to obtain the dose rate H of the third electron beam. c ;

[0035] S8: The third data processing system performs a dose H of the third electron beam on the third electron beam. c The data is further processed to obtain the dose H' of the second electron beam b .

[0036] Preferably, the dose rate H of the first electron beam in step S4 is a The dose rate H of the second electron beam b There is a linear numerical relationship: H b =K1H a .

[0037] Preferably, the dose rate H of the third electron beam in step S8 is a The dose rate H' of the second electron beam b There is a linear numerical relationship: H' b =K2H c .

[0038] Preferably, the steps of determining K1 are as follows:

[0039] P1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the first beam outlet tube to form the first electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, where n is a positive integer;

[0040] P2: the first electron beam is injected into a first dose probe, and the first dose probe collects a first signal; the second electron beam is injected into a second dose probe, and the second dose probe collects a second signal;

[0041] P3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H21 of the second electron beam;

[0042] P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate H2(H22,H23,H24,H2 i ,┉);

[0043] P5: Set the dose rate of the first electron beam H1 (H11, H12, H13, H14, H1 i ,┉) and the dose rate H2(H21,H22,H23,H24,H2 i ,┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K1 is obtained.

[0044] Preferably, the steps of determining K2 are as follows:

[0045] Q1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the second beam outlet tube to form the third electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, wherein n is a positive integer;

[0046] Q2: the third electron beam is injected into the third dose probe, and the third dose probe collects the third signal; the second electron beam is injected into the second dose probe, and the second dose probe collects the second signal;

[0047] Q3: the third dose probe completes collecting the third signal, and the third data processing system processes the third signal to obtain the dose rate H31 of the third electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H41 of the second electron beam;

[0048] Q4: Repeat steps Q1-Q3 to obtain a series of dose rates H3 (H32, H33, H34, H3 i ,┉) and the dose rate H4(H42,H43,H44,H4 i ,┉);

[0049] Q5: Set the dose rate of the third electron beam H3 (H31, H32, H33, H34, H3 i ,┉) and the dose rate H4 (H41, H42, H43, H44, H4 i ,┉) take the average value to obtain the average dose rate of the third electron beam and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K2 is obtained.

[0050] Preferably, before step S1, the method further includes: placing the head end of the first dose probe opposite to the outlet of the first beam extraction tube and on the same central axis; placing the head end of the third dose probe opposite to the outlet of the second beam extraction tube and on the same central axis.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. The present invention is provided with a deflection magnetic field and a beam extraction tube to "extract" some electrons for realizing the dose test and monitoring of the electron beam, and has a novel structure;

[0053] 2. The dose value of the electron beam is obtained by testing the "extracted" electrons and processing them through the dose detector. This process does not affect the treatment process and can monitor the dose online, thus improving the convenience and accuracy of treatment.

[0054] 3. Only one K value needs to be determined before treatment, which can realize continuous and multiple monitoring of the treatment process, and the operation is convenient;

[0055] 4. Use dual dose detectors to ensure the effectiveness of the dose detectors in the event that one of the dose detectors fails, thereby improving patient safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0057] Figure 1 This is a basic structural block diagram of the medical accelerator of this application;

[0058] Figure 2 A schematic diagram of the structure of an accelerating tube, a beam needle and a dose detector in a medical accelerator in one embodiment;

[0059] Figure 3 A schematic diagram of the position of a deflection magnetic field generating device in one embodiment;

[0060] Figure 4 for Figure 2 Diagram of steps for conducting dose monitoring methods;

[0061] Figure 5 A schematic diagram of the arrangement of dose detectors when determining the K value in an embodiment;

[0062] Figure 6 A diagram showing the steps for determining the K value;

[0063] Figure 7 is a schematic structural diagram of an accelerating tube, a beam needle and a dose detector in a medical accelerator in another embodiment;

[0064] Figure 8 A schematic diagram of the position of a deflection magnetic field generating device in another embodiment;

[0065] Figure markings: 1-medical accelerator, 2-electron gun control power supply, 3-electron gun, 4-accelerating tube, 5-magnetron, 6-modulator, 7-beam pipe, 8-beam needle, 9-beam extraction tube, 9a-first beam extraction tube, 9c-second beam extraction tube, 10-deflection magnetic field generating device, 11-first electromagnet, 12-second electromagnet, 13-first connecting part, 14-second connecting part, 15-dose detector, 16-dose probe, 17-data processing system, 16a-first dose probe, 17a-first data processing system, 16b-second dose probe, 17b-second data processing system, 16c-third dose probe, 17c-third data processing system. DETAILED DESCRIPTION

[0066] In order to further understand the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0067] It should be noted that the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or more of the features. The term "distal end" refers to the end farthest from the reader when the device or equipment of the present application is facing the reader; the "proximal end" refers to the end closest to the reader when the device or equipment of the present application is facing the reader. The term "front end" or "export end" refers to the end close to the beam needle tip or the beam outlet nozzle when the device or equipment of the present application is facing the reader; the "rear end" or "inlet end" refers to the end farthest from the beam needle tip or the beam outlet nozzle when the device or equipment of the present application is facing the reader.

[0068] The present invention provides a medical accelerator, please refer to Figure 1-3 , including an electron gun control power supply 2, an electron gun 3, an accelerating tube 4, a magnetron 5, a modulator 6, a beam pipe 7 and a beam needle 8; the electron gun control power supply 2 is used to control the injection voltage of the electron gun 3; the electron gun 3 is used to output an electron beam, the accelerating tube 4 is used to accelerate the electron beam output by the electron gun 3 and then output it through the beam needle 8; the modulator 6 is used to control the magnetron 5; the magnetron 5 is connected to the accelerating tube 4 through a waveguide chain; the rear end of the beam pipe 7 is fixedly connected to the front end center of the accelerating tube 4, the The front end of the beam pipe 7 is connected to the beam needle 8; the accelerating tube 4, the beam pipe 7 and the beam needle 8 have a common central axis and are connected to form a straight channel for the electron beam to be transmitted in the straight channel; the side of the beam pipe 7 is connected to the beam extraction tube 9, and the first electron beam is transmitted in the beam extraction tube 9. A deflection magnetic field generating device 10 is arranged on the periphery of the beam pipe 7 to periodically cause the electron beam to change its transmission direction and be output from the beam extraction tube 9 to form the first electron beam; the electron beam output by the beam needle 8 is the second electron beam.

[0069] The treatment process of the present invention is as follows: the beam needle 8 is introduced into the tumor lesion site in the human body through a trocar (not shown) preset on the human body, the electron gun 3 generates an electron beam, which is accelerated by the accelerating tube 4 and finally output through the beam needle 8. The electron beam hits the tumor lesion site to ablate the tumor.

[0070] The treatment process of the present invention can also be as follows: the tumor lesion site is exposed through surgery or other means, the beam needle 8 is introduced into the tumor lesion site in the human body, the electron gun 3 generates an electron beam, which is accelerated by the accelerating tube 4 and finally output through the beam needle 8. The electron beam hits the tumor lesion site to ablate the tumor.

[0071] The waveguide chain of this embodiment is a soft waveguide, which has good flexibility and can withstand a certain degree of bending, stretching and compression. When the accelerating tube 4 and the magnetron 5 are separately arranged, the transmission of the electron beam is guaranteed.

[0072] In order to enable the electron beam to be smoothly transmitted from the beam needle 8, a focusing coil is arranged on the periphery of the connection structure between the accelerating tube 4 and the beam needle 8, which is beneficial to effectively guide the movement path of the electron beam and ensure that the electron beam is gathered on the axis of the beam needle 8.

[0073] Since the dose of the electron beam must be monitored during the treatment process, the present invention "extracts" a very small part of the electron beam for synchronous testing through the beam extraction tube 9 and the deflection magnetic field generating device 10, which does not affect the treatment process and can achieve online dose monitoring.

[0074] Furthermore, the outlet ends of the beam needle 8 and the beam outlet tube 9 are both sealed ends.

[0075] By adopting the above technical solution, the internal environment of the entire accelerator is maintained in a vacuum environment, and electrons can achieve vacuum low-loss transmission.

[0076] In this embodiment, the beam needle 8 and the exit end of the beam extraction tube 9 are made of the same material, and the sealing end is a non-magnetic metal sheet, preferably a titanium sheet or a beryllium sheet. The thickness of the sealing end is less than 200 μm. After long-term experiments and research, it is found that if the sealing end is too thick, electrons cannot pass through. When a titanium sheet or a beryllium sheet is used as a sealing material, the electron passing condition is better and the attenuation degree of the electron is lighter. At this time, both the effective electron passing rate and the sealing of the space inside the tube can be guaranteed.

[0077] For further information, please refer to Figure 3 The magnetic field direction of the deflection magnetic field generating device 10 is perpendicular to the plane formed by the beam extraction tube 9 and the beam pipeline 7. When the beam extraction tube 9 is located to the right of the accelerating tube 4, the magnetic field direction of the deflection magnetic field points from the distal end to the proximal end.

[0078] Specifically, the deflection magnetic field generating device 10 is a pair of electromagnets. The electromagnets are magnetic when powered on, and the magnetism disappears when powered off, so as to facilitate rapid regulation of the deflection of the electron beam. Preferably, two identical electromagnets are used and are equidistantly located on both sides of the beam needle 8, with the first electromagnet 11 at the far end and the second electromagnet 12 at the near end.

[0079] By adopting the above technical solution, the transmission direction of the electron beam is changed from parallel to the central axis of the beam duct 7 to parallel to the central axis of the beam extraction tube 9, forming a first electron beam for detecting the dose rate of the electron beam.

[0080] Furthermore, a first connection portion 13 is disposed at the front end of the beam pipe 7 , and a second connection portion 14 is disposed at the inlet end of the beam needle 8 . The first connection portion 13 and the second connection portion 14 are detachably connected.

[0081] By adopting the above technical solution, the beam pipe 7 and the beam needle 8 can be disassembled. Since the beam needle 8 is a relatively thin hollow tube with an outer diameter of generally 1.5-6 mm, if it is damaged for some reason, the beam needle 8 can be replaced by disassembly.

[0082] The present invention also provides a dose monitoring method for monitoring a medical accelerator of any of the above embodiments, please refer to Figure 4 , including the following steps:

[0083] S1: within a time Δt, the deflection magnetic field generating device 10 works to change the transmission direction of the electron beam and output it from the beam extraction tube 9 to form the first electron beam;

[0084] S2: the first electron beam is emitted into the first dose probe 16a, and the first dose probe 16a collects a first signal;

[0085] S3: The first dose probe 16a completes collecting the first signal, and the first data processing system 17a processes the first signal to obtain the dose rate H of the first electron beam. a ;

[0086] S4: The first data processing system 17a processes the dose H of the first electron beam a The data is further processed to obtain the dose H of the second electron beam. b ;.

[0087] Further, in step S4, the dose rate H of the first electron beam is a The dose rate H of the second electron beam b There is a linear numerical relationship: H b =KH a .

[0088] Figure 5 Schematic diagram of the arrangement of dose detectors when determining the K value in one embodiment.

[0089] Further, the steps for determining K are as follows, please refer to Figure 6 :

[0090] P1: During the time Δt, the deflection magnetic field generating device 10 works, causing the electron beam to change its transmission direction and output from the beam lead-out tube 9 to form the first electron beam; during the time nΔt, the deflection magnetic field generating device 10 stops working, the electron beam is transmitted along the straight channel and output from the beam needle 8 to form the second electron beam, wherein n is a positive integer;

[0091] P2: the first electron beam is incident on the first dose probe 16a, and the first dose probe 16a collects a first signal; the second electron beam is incident on the second dose probe 16b, and the second dose probe 16b collects a second signal;

[0092] P3: The first dose probe 16a completes collecting the first signal, and the first data processing system 17a processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe 16b completes collecting the second signal, and the second data processing system 17b processes the second signal to obtain the dose rate H21 of the second electron beam;

[0093] P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate H2(H22,H23,H24,H2 i ,┉);

[0094] P5: Set the dose rate of the first electron beam H1 (H11, H12, H13, H14, H1 i ,┉) and the dose rate H2(H21,H22,H23,H24,H2 i ,┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K is obtained.

[0095] In the pulse working mode, the time characteristics of the electron beam generation have pulse characteristics. For example, if the repetition frequency is 5 Hz, 5 current pulses are generated within 1 s, the pulse repetition period is 200 ms, and the pulse width is 1 to 4 us.

[0096] Furthermore, before step S1, the method further includes: placing the head end of the dose probe 16 opposite to the outlet of the beam extraction tube and on the same central axis.

[0097] Please refer to Figure 2The dose detector 15 used in the present invention includes a dose probe 16 and a data processing system 17. The data processing system 17 processes the signal monitored by the dose probe 16 to obtain the dose of the electron beam; the head end of the dose probe 16 is opposite to the outlet of the beam extraction tube 9 and is on the same central axis.

[0098] Specifically, the dose probe 16 of the dose detector 15 of the present embodiment includes a finger-shaped ionization chamber, preferably a UNIDOS E dosimeter produced by PTW of Germany. The UNIDOS E dosimeter can monitor the signal at the exit of the beam extraction tube 9 and directly obtain the dose of the first electron beam; similarly, the UNIDOS E dosimeter can monitor the signal at the exit of the beam needle 8 and directly obtain the dose of the second electron beam.

[0099] The principle of measuring absorbed dose by finger-shaped ionization chamber is: first measure the ionization charge generated by ionizing radiation, then use the average ionization energy of air to calculate and convert it into the energy deposited by ionizing radiation, that is, absorbed dose.

[0100] When the accelerator performs radiotherapy, there will be ionizing radiation, which will affect the health of doctors and technicians. In this embodiment, the dose probe 16 and the data processing system 17 transmit data wirelessly or wired. Doctors or technicians can measure and monitor the dose online through remote operation.

[0101] Specifically, the wireless method is one of WIFI, cellular network, microwave communication, and Bluetooth.

[0102] Specifically, the wired mode is one of optical fiber transmission, twisted pair transmission, coaxial cable transmission, and broadband coaxial cable transmission.

[0103] The present invention "extracts" a very small part of the electron beam for synchronous testing through the beam extraction tube 9 and the deflection magnetic field generating device 10, which does not affect the treatment process and can realize online monitoring of the dose.

[0104] In order to reduce the error of the dose test result, the distance between the first dose probe 16a and the outlet end of the beam extraction tube 9 and the distance between the second dose probe 16b and the outlet end of the beam needle 8 are equal and kept constant.

[0105] Example 1

[0106] Before treatment, the above steps P1-P5 were followed, Δt=1s, and the test data were obtained as shown in Table 1.

[0107] Table 1 Test results of H1 and H2 (unit: Gy / min)

[0108]

[0109]

[0110] By processing the test results of H1 and H2, K=4 is obtained.

[0111] Example 2

[0112] During the treatment, the dose monitoring is performed according to steps S1-S4, Δt = 1s, n = 5, and the dose rate H of the first electron beam is a The test value and the dose rate H of the second electron beam b The calculated values ​​are shown in Table 2.

[0113] Table 2 Test results of H1 and H2 (unit: Gy / min)

[0114] Number of tests <![CDATA[H a Test value]]> <![CDATA[H b Calculated value]]> Number of tests <![CDATA[H a Test value]]> <![CDATA[H b Calculated value]]> 1 16.26 65.05 14 16.26 65.03 2 16.75 66.99 15 16.47 65.89 3 16.56 66.22 16 16.52 66.06 4 15.95 63.79 17 16.74 66.96 5 16.54 66.17 18 16.30 65.18 6 16.77 67.07 19 16.03 64.10 7 16.39 65.56 20 16.29 65.16 8 16.86 67.45 21 16.55 66.19 9 16.65 66.58 22 16.26 65.02 10 16.82 67.27 23 16.03 64.10 11 16.25 64.98 24 16.27 65.08 12 16.13 64.52 25 16.25 64.98 13 16.81 67.22

[0115] In this embodiment, the dose rate of the second electron beam (used for treatment) is calculated by monitoring the dose rate of the first electron beam, and the dose rate monitoring is implemented without affecting the treatment.

[0116] For safety reasons and to avoid failure of the dose detector 15, in another technical solution, two groups of the dose detectors 15 and two groups of beam extraction tubes 9 are provided. Both groups of the dose detectors 15 can obtain the dose rate. If one group of the dose detectors 15 fails, the other group can continue to work. In addition, the two groups of dose rate data can also be compared to examine the stability of the data.

[0117] In another embodiment, a medical accelerator is shown in FIG. Figure 7-8, including an electron gun control power supply 2, an electron gun 3, an accelerating tube 4, a magnetron 5, a modulator 6, a beam pipe 7 and a beam needle 8; the electron gun control power supply 2 is used to control the injection voltage of the electron gun 3; the electron gun 3 is used to output an electron beam, and the accelerating tube 4 is used to accelerate the electron beam output by the electron gun 3 and output it through the beam needle 8; the modulator 6 is used to control the magnetron 5; the magnetron 5 is connected to the accelerating tube 4 through a waveguide chain; the rear end of the beam pipe 7 is fixedly connected to the front end center of the accelerating tube 4, and the front end of the beam pipe 7 is connected to the beam needle 8; the accelerating tube 4, the beam pipe 7, and the beam needle 8 have a common central axis and are connected to form a straight line channel. , the electron beam is transmitted in the straight channel; the side of the beam pipe 7 is connected to the first beam lead-out tube 9a and the second beam lead-out tube 9b, the first beam lead-out tube 9a and the second beam lead-out tube 9b are symmetrically arranged with respect to the beam pipe 7, the first electron beam is transmitted in the first beam lead-out tube 9a, and the third electron beam is transmitted in the second beam lead-out tube 9b, a deflection magnetic field generating device 10 is arranged at the periphery of the beam pipe 7, which periodically causes the electron beam to change the transmission direction and output from the first beam lead-out tube 9a to form the first electron beam, and periodically causes the electron beam to change the transmission direction and output from the second beam lead-out tube 9b to form the third electron beam; the electron beam output by the beam needle 8 is the second electron beam.

[0118] Furthermore, the magnetic field direction of the deflection magnetic field generating device 10 is perpendicular to the plane formed by the first beam extraction tube 9a and the beam pipe 7. When the first electron beam is required to be output from the first beam extraction tube 9a, the magnetic field direction of the deflection magnetic field is from the distal end to the proximal end. When the third electron beam is required to be output from the second beam extraction tube 9b, the magnetic field direction of the deflection magnetic field is from the proximal end to the distal end.

[0119] Specifically, the change of the magnetic field direction of the deflection magnetic field is achieved by changing the current direction of the spiral line.

[0120] A dose monitoring method for a medical accelerator according to another embodiment is characterized by comprising the following steps:

[0121] S1: within a time period Δt, the deflection magnetic field generating device 10 operates to change the transmission direction of the electron beam and output it from the first beam outlet tube 9a to form the first electron beam;

[0122] S2: the first electron beam is emitted into the first dose probe 16a, and the first dose probe 16a collects a first signal;

[0123] S3: The first dose probe 16a completes collecting the first signal, and the first data processing system 17a processes the first signal to obtain the dose rate H of the first electron beam. a ;

[0124] S4: The first data processing system 17a processes the dose H of the first electron beam a The data is further processed to obtain the dose H of the second electron beam. b .

[0125] S5: the deflection magnetic field generating device 10 works within a time Δt, so that the electron beam changes its transmission direction and is output from the first beam outlet tube 9b to form the third electron beam;

[0126] S6: the third electron beam is injected into the third dose probe 16c, and the third dose probe 16c collects a third signal;

[0127] S7: The third dose probe 16c completes collecting the third signal, and the third data processing system 17c processes the third signal to obtain the dose rate H of the third electron beam. c ;

[0128] S8: The third data processing system 17c processes the dose H of the third electron beam c The data is further processed to obtain the dose H' of the second electron beam b .

[0129] Further, in step S4, the dose rate H of the first electron beam is a The dose rate H of the second electron beam b There is a linear numerical relationship: H b =K1H a .

[0130] Furthermore, the dose rate H of the third electron beam in step S8 is a The dose rate H' of the second electron beam b There is a linear numerical relationship: H' b =K2H c .

[0131] Further, the steps for determining K1 are as follows:

[0132] P1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the first beam outlet tube 9a to form the first electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, wherein n is a positive integer;

[0133] P2: the first electron beam is injected into the first dose probe 16a, and the first dose probe 16a collects a first signal; the second electron beam is injected into the second dose probe, and the second dose probe collects a second signal;

[0134] P3: The first dose probe 16a completes collecting the first signal, and the first data processing system 17a processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe 16b completes collecting the second signal, and the second data processing system 17b processes the second signal to obtain the dose rate H21 of the second electron beam;

[0135] P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate H2(H22,H23,H24,H2 i ,┉);

[0136] P5: Set the dose rate of the first electron beam H1 (H11, H12, H13, H14, H1 i ,┉) and the dose rate H2(H21,H22,H23,H24,H2 i ,┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K1 is obtained.

[0137] Further, the steps for determining K2 are as follows:

[0138] Q1: During the time Δt, the deflection magnetic field generating device 10 works, causing the electron beam to change its transmission direction and output from the first beam outlet tube 9b to form the third electron beam; during the time nΔt, the deflection magnetic field generating device 10 stops working, the electron beam is transmitted along the straight channel and output from the beam needle 8 to form the second electron beam, wherein n is a positive integer;

[0139] Q2: the third electron beam is injected into the third dose probe 16c, and the third dose probe 16c collects the third signal; the second electron beam is injected into the second dose probe 16b, and the second dose probe 16b collects the second signal;

[0140] Q3: The third dose probe 16c completes collecting the third signal, and the third data processing system 17c processes the third signal to obtain the dose rate H31 of the third electron beam; the second dose probe 16b completes collecting the second signal, and the second data processing system 17b processes the second signal to obtain the dose rate H41 of the second electron beam;

[0141] Q4: Repeat steps Q1-Q3 to obtain a series of dose rates H3 (H32, H33, H34, H3 i ,┉) and the dose rate H4(H42,H43,H44,H4 i ,┉);

[0142] Q5: Set the dose rate of the third electron beam H3 (H31, H32, H33, H34, H3 i ,┉) and the dose rate H4 (H41, H42, H43, H44, H4 i ,┉) take the average value to obtain the average dose rate of the third electron beam and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K2 is obtained.

[0143] Furthermore, before step S1, the step also includes: placing the head end of the first dose probe 16a opposite to the outlet of the first beam extraction tube 9a and on the same central axis; placing the head end of the third dose probe 16c opposite to the outlet of the first beam extraction tube 9b and on the same central axis.

[0144] Example 3

[0145] Before treatment, the above steps Q1-Q5 were followed, Δt=1s, and the test data were obtained as shown in Table 3.

[0146] Table 1 Test results of H3 and H4 (unit: Gy / min)

[0147]

[0148] By processing the test results of H3 and H4, K=4 is obtained.

[0149] Example 4

[0150] During the treatment, the dose monitoring is performed according to steps S1-S8, Δt=1s, n=5, and the dose rate H of the first electron beam is a Test value, dose rate H of the third electron beam c The test value and the dose rate H of the second electron beam b, H' b The calculated values ​​are shown in Table 4.

[0151] Table 2 H a , H c , H b and H' b Test results table (unit: Gy / min)

[0152]

[0153]

[0154] It can be seen from Table 4 that the dose rate H of the second electron beam monitored by the first electron beam of the first beam extraction tube 9a is b , and the dose rate H' of the second electron beam monitored by the third electron beam through the second beam extraction tube 9b b The results are similar, indicating that the dose monitoring method of the present application is feasible and reliable.

[0155] The present invention "extracts" a very small part of the electron beam for synchronous testing through the beam extraction tube 9 and the deflection magnetic field generating device 10, and only needs to be calibrated before treatment. The dosage measurement steps of the present invention are simple, do not affect the treatment process, and realize online dosage monitoring.

[0156] For those skilled in the art, the embodiments should be regarded as illustrative and non-restrictive. The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A medical accelerator, characterized in that: The invention comprises an electron gun control power supply, an electron gun, an accelerating tube, a magnetron, a modulator, a beam pipe and a beam needle; the electron gun control power supply is used to control the injection voltage of the electron gun; the electron gun is used to output an electron beam, the accelerating tube is used to accelerate the electron beam output by the electron gun and then output it through the beam needle; the modulator is used to control the magnetron; the magnetron is connected to the accelerating tube through a waveguide chain; the rear end of the beam pipe is fixedly connected to the front end center of the accelerating tube, and the front end of the beam pipe is connected to the beam needle; the accelerating tube, the beam pipe and the beam needle have a common central axis and are connected to form a straight line channel for the electron beam to be transmitted in the straight line channel; the side of the beam pipe is connected to a beam extraction tube, the first electron beam is transmitted in the beam extraction tube, a deflection magnetic field generating device is arranged on the periphery of the beam pipe, and the electron beam is periodically forced to change the transmission direction and output from the beam extraction tube to form the first electron beam; the electron beam output by the beam needle is a second electron beam; The dose monitoring process of the medical accelerator includes the following steps: S1: the deflection magnetic field generating device works within a time Δt, causing the electron beam to change its transmission direction and be output from the beam extraction tube to form the first electron beam; S2: the first electron beam is emitted into a first dose probe, and the first dose probe collects a first signal; S3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H of the first electron beam. a ; S4: The first data processing system determines the dose rate H of the first electron beam a The data is further processed to obtain the dose rate H of the second electron beam. b ; Wherein, the dose rate H of the first electron beam in step S4 is a The dose rate H of the second electron beam b There is a linear numerical relationship: H b =KH a ; The steps for determining K are as follows: P1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the beam outlet tube to form the first electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, wherein n is a positive integer; P2: the first electron beam is injected into a first dose probe, and the first dose probe collects a first signal; the second electron beam is injected into a second dose probe, and the second dose probe collects a second signal; P3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H21 of the second electron beam; P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate of the second electron beam H2 (H22, H23,H24,H2 i ,┉); P5: Set the dose rate of the first electron beam to H1 (H11, H12, H13, H14, H1 i , ┉) and the dose rate of the second electron beam H2 (H21, H22, H23, H24, H2 i , ┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam , we get a linear numerical relationship: =K , that is, the value of K is obtained; Wherein, before step S1, the method further includes: placing the head end of the dose probe opposite to the outlet of the beam extraction tube and on the same central axis.

2. The medical accelerator according to claim 1, characterized in that: The outlet ends of the beam needle and the beam outlet tube are both sealed ends.

3. The medical accelerator according to claim 1, characterized in that: The magnetic field direction of the deflection magnetic field generating device is perpendicular to the plane formed by the beam extraction tube and the beam pipeline. When the beam extraction tube is located to the right of the accelerating tube, the direction of the deflection magnetic field points from the far end to the near end.

4. The medical accelerator according to claim 1, characterized in that: A first connection part is arranged at the front end of the beam pipe, and a second connection part is arranged at the inlet end of the beam needle. The first connection part and the second connection part are detachably connected.

5. A dose monitoring method for measuring the dose of a medical accelerator, characterized in that: The medical accelerator comprises an electron gun control power supply, an electron gun, an accelerating tube, a magnetron, a modulator, a beam pipe and a beam needle; the electron gun control power supply is used to control the electron gun injection voltage; the electron gun is used to output an electron beam, the accelerating tube is used to accelerate the electron beam output by the electron gun and then output it through the beam needle; the modulator is used to control the magnetron; the magnetron is connected to the accelerating tube through a waveguide chain; the rear end of the beam pipe is fixedly connected to the front end center of the accelerating tube, and the front end of the beam pipe is connected to the beam needle; the accelerating tube, the beam pipe and the beam needle have a common central axis and are connected to form a straight line channel for the electron beam to be transmitted in the straight line channel; the side of the beam pipe is connected to a beam extraction tube, the first electron beam is transmitted in the beam extraction tube, a deflection magnetic field generating device is arranged on the periphery of the beam pipe, which periodically causes the electron beam to change the transmission direction and output from the beam extraction tube to form the first electron beam; the electron beam output by the beam needle is a second electron beam; the dose monitoring method comprises the following steps: S1: the deflection magnetic field generating device works within a time Δt, causing the electron beam to change its transmission direction and be output from the beam extraction tube to form the first electron beam; S2: the first electron beam is emitted into a first dose probe, and the first dose probe collects a first signal; S3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H of the first electron beam. a ; S4: The first data processing system determines the dose rate H of the first electron beam a The data is further processed to obtain the dose rate H of the second electron beam. b ; Wherein, the dose rate H of the first electron beam in step S4 is a The dose rate H of the second electron beam b There is a linear numerical relationship: H b =KH a ; The steps for determining K are as follows: P1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the beam outlet tube to form the first electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, wherein n is a positive integer; P2: the first electron beam is injected into a first dose probe, and the first dose probe collects a first signal; the second electron beam is injected into a second dose probe, and the second dose probe collects a second signal; P3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H21 of the second electron beam; P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate of the second electron beam H2 (H22, H23,H24,H2 i ,┉); P5: Set the dose rate of the first electron beam to H1 (H11, H12, H13, H14, H1 i , ┉) and the dose rate of the second electron beam H2 (H21, H22, H23, H24, H2 i , ┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam , we get a linear numerical relationship: =K , that is, the value of K is obtained; Wherein, before step S1, the method further includes: placing the head end of the dose probe opposite to the outlet of the beam extraction tube and on the same central axis.

6. The dose monitoring method according to claim 5, characterized in that: The dose probe and the data processing system perform data transmission wirelessly or wiredly.

7. A medical accelerator, characterized in that: The invention comprises an electron gun control power supply, an electron gun, an accelerating tube, a magnetron, a modulator, a beam pipe and a beam needle; the electron gun control power supply is used to control the injection voltage of the electron gun; the electron gun is used to output an electron beam, the accelerating tube is used to accelerate the electron beam output by the electron gun and then output it through the beam needle; the modulator is used to control the magnetron; the magnetron is connected to the accelerating tube through a waveguide chain; the rear end of the beam pipe is fixedly connected to the front end center of the accelerating tube, and the front end of the beam pipe is connected to the beam needle; the accelerating tube, the beam pipe and the beam needle have a common central axis and are connected to form a straight line channel for The electron beam is transmitted in the linear channel; the first beam lead-out tube and the second beam lead-out tube are connected to the side of the beam pipe, the first beam lead-out tube and the second beam lead-out tube are symmetrically arranged with respect to the beam pipe, the first electron beam is transmitted in the first beam lead-out tube, and the third electron beam is transmitted in the second beam lead-out tube; a deflection magnetic field generating device is arranged at the periphery of the beam pipe, which periodically causes the electron beam to change the transmission direction and output from the first beam lead-out tube to form the first electron beam, and periodically causes the electron beam to change the transmission direction and output from the second beam lead-out tube to form the third electron beam; the electron beam output by the beam needle is the second electron beam; The dose monitoring process of the medical accelerator includes the following steps: S1: the deflection magnetic field generating device works within a time Δt, causing the electron beam to change its transmission direction and be output from the first beam outlet tube to form the first electron beam; S2: the first electron beam is emitted into a first dose probe, and the first dose probe collects a first signal; S3: After the first dose probe collects the first signal, the first data processing system processes the first signal to obtain the dose rate H of the first electron beam. a ; S4: The first data processing system determines the dose rate H of the first electron beam a The data is further processed to obtain the dose rate H of the second electron beam. b ; S5: the deflection magnetic field generating device operates within a time Δt, so that the electron beam changes its transmission direction and is output from the second beam outlet tube to form the third electron beam; S6: the third electron beam is injected into a third dose probe, and the third dose probe collects a third signal; S7: The third dose probe completes collecting the third signal, and the third data processing system processes the third signal to obtain the dose rate H of the third electron beam. c ; S8: The third data processing system performs a dose rate H of the third electron beam on the third electron beam. c The data is further processed to obtain the dose rate H' of the second electron beam b ; Wherein, in step S4, there is a linear numerical relationship between the dose rate Ha of the first electron beam and the dose rate Hb of the second electron beam: Hb=K1Ha; The dose rate H of the third electron beam in step S8 is c The dose rate H' of the second electron beam b There is a linear numerical relationship: H' b =K2H c ; The steps for determining K1 are as follows: P1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the first beam outlet tube to form the first electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, where n is a positive integer; P2: the first electron beam is injected into a first dose probe, and the first dose probe collects a first signal; the second electron beam is injected into a second dose probe, and the second dose probe collects a second signal; P3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H21 of the second electron beam; P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate of the second electron beam H2 (H22, H23,H24,H2 i ,┉); P5: Set the dose rate of the first electron beam to H1 (H11, H12, H13, H14, H1 i , ┉) and the dose rate of the second electron beam H2 (H21, H22, H23, H24, H2 i , ┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam , we get a linear numerical relationship: =K1 , that is, the value of K1 is obtained; The steps for determining K2 are as follows: Q1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the second beam outlet tube to form the third electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, wherein n is a positive integer; Q2: the third electron beam is injected into the third dose probe, and the third dose probe collects the third signal; the second electron beam is injected into the second dose probe, and the second dose probe collects the second signal; Q3: the third dose probe completes collecting the third signal, and the third data processing system processes the third signal to obtain the dose rate H31 of the third electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H41 of the second electron beam; Q4: Repeat steps Q1-Q3 to obtain a series of dose rates H3 (H32, H33, H34, H3 i , ┉) and the dose rate H4 of the second electron beam (H42, H43, H44, H4 i ,┉); Q5: Set the dose rate of the third electron beam H3 (H31, H32, H33, H34, H3 i , ┉) and the dose rate H4 of the second electron beam (H41, H42, H43, H44, H4 i , ┉) take the average value to obtain the average dose rate of the third electron beam and the average dose rate of the second electron beam , we get a linear numerical relationship: =K2 , that is, the value of K2 is obtained; Wherein, before step S1, the method further includes: placing the head end of the first dose probe opposite to the outlet of the first beam extraction tube and on the same central axis; placing the head end of the third dose probe opposite to the outlet of the second beam extraction tube and on the same central axis.

8. The medical accelerator according to claim 7, characterized in that: The outlet ends of the beam needle and the beam outlet tube are both sealed ends.

9. The medical accelerator according to claim 7, characterized in that: The magnetic field direction of the deflection magnetic field generating device is perpendicular to the plane formed by the first beam extraction tube and the beam pipe. When the first electron beam is required to be output from the first beam extraction tube, the magnetic field direction of the deflection magnetic field is from the distal end to the proximal end. When the third electron beam is required to be output from the second beam extraction tube, the magnetic field direction of the deflection magnetic field is from the proximal end to the distal end.

10. A dose monitoring method for measuring the dose of a medical accelerator, characterized in that: The medical accelerator comprises an electron gun control power supply, an electron gun, an accelerating tube, a magnetron, a modulator, a beam pipe and a beam needle; the electron gun control power supply is used to control the injection voltage of the electron gun; the electron gun is used to output an electron beam, and the accelerating tube is used to accelerate the electron beam output by the electron gun and output it through the beam needle; the modulator is used to control the magnetron; the magnetron is connected to the accelerating tube through a waveguide chain; the rear end of the beam pipe is fixedly connected to the front end center of the accelerating tube, and the front end of the beam pipe is connected to the beam needle; the accelerating tube, the beam pipe and the beam needle have a common central axis and are connected to form a straight line channel for the electron beam to pass through the accelerating tube. The straight channel is transmitted; the side of the beam pipe is connected to the first beam lead-out tube and the second beam lead-out tube, the first beam lead-out tube and the second beam lead-out tube are symmetrically arranged with respect to the beam pipe, the first electron beam is transmitted in the first beam lead-out tube, and the third electron beam is transmitted in the second beam lead-out tube, a deflection magnetic field generating device is arranged on the periphery of the beam pipe, which periodically causes the electron beam to change the transmission direction and output from the first beam lead-out tube to form the first electron beam, and periodically causes the electron beam to change the transmission direction and output from the second beam lead-out tube to form the third electron beam; the electron beam output by the beam needle is the second electron beam; the dose monitoring method comprises the following steps: S1: the deflection magnetic field generating device works within a time Δt, causing the electron beam to change its transmission direction and be output from the first beam outlet tube to form the first electron beam; S2: the first electron beam is emitted into a first dose probe, and the first dose probe collects a first signal; S3: After the first dose probe collects the first signal, the first data processing system processes the first signal to obtain the dose rate H of the first electron beam. a ; S4: The first data processing system determines the dose rate H of the first electron beam a The data is further processed to obtain the dose rate H of the second electron beam. b ; S5: the deflection magnetic field generating device operates within a time Δt, so that the electron beam changes its transmission direction and is output from the second beam outlet tube to form the third electron beam; S6: the third electron beam is injected into a third dose probe, and the third dose probe collects a third signal; S7: The third dose probe completes collecting the third signal, and the third data processing system processes the third signal to obtain the dose rate H of the third electron beam. c ; S8: The third data processing system performs a dose rate H of the third electron beam on the third electron beam. c The data is further processed to obtain the dose rate H' of the second electron beam b ; Wherein, in step S4, there is a linear numerical relationship between the dose rate Ha of the first electron beam and the dose rate Hb of the second electron beam: Hb=K1Ha; The dose rate H of the third electron beam in step S8 is c The dose rate H' of the second electron beam b There is a linear numerical relationship: H' b =K2H c ; The steps for determining K1 are as follows: P1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the first beam outlet tube to form the first electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, where n is a positive integer; P2: the first electron beam is injected into a first dose probe, and the first dose probe collects a first signal; the second electron beam is injected into a second dose probe, and the second dose probe collects a second signal; P3: The first dose probe completes collecting the first signal, and the first data processing system processes the first signal to obtain the dose rate H11 of the first electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H21 of the second electron beam; P4: Repeat steps P1-P3 to obtain a series of dose rates H1 (H12, H13, H14, H1 i ,┉) and the dose rate of the second electron beam H2 (H22, H23,H24,H2 i ,┉); P5: Set the dose rate of the first electron beam to H1 (H11, H12, H13, H14, H1 i , ┉) and the dose rate of the second electron beam H2 (H21, H22, H23, H24, H2 i , ┉) take the average value to obtain the average dose rate of the first electron beam and the average dose rate of the second electron beam , we get a linear numerical relationship: =K1 , that is, the value of K1 is obtained; The steps for determining K2 are as follows: Q1: During the time Δt, the deflection magnetic field generating device works, causing the electron beam to change its transmission direction and output from the second beam outlet tube to form the third electron beam; during the time nΔt, the deflection magnetic field generating device stops working, the electron beam is transmitted along the straight channel and output from the beam needle to form the second electron beam, wherein n is a positive integer; Q2: the third electron beam is injected into the third dose probe, and the third dose probe collects the third signal; the second electron beam is injected into the second dose probe, and the second dose probe collects the second signal; Q3: the third dose probe completes collecting the third signal, and the third data processing system processes the third signal to obtain the dose rate H31 of the third electron beam; the second dose probe completes collecting the second signal, and the second data processing system processes the second signal to obtain the dose rate H41 of the second electron beam; Q4: Repeat steps Q1-Q3 to obtain a series of dose rates H3 (H32, H33, H34, H3 i , ┉) and the dose rate H4 of the second electron beam (H42, H43, H44, H4 i ,┉); Q5: Set the dose rate of the third electron beam H3 (H31, H32, H33, H34, H3 i , ┉) and the dose rate H4 of the second electron beam (H41, H42, H43, H44, H4 i , ┉) take the average value to obtain the average dose rate of the third electron beam and the average dose rate of the second electron beam , we get a linear numerical relationship: =K2 , that is, the value of K2 is obtained; Wherein, before step S1, the method further includes: placing the head end of the first dose probe opposite to the outlet of the first beam extraction tube and on the same central axis; placing the head end of the third dose probe opposite to the outlet of the second beam extraction tube and on the same central axis.

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