A medical accelerator, a dose monitoring system and a dose monitoring method thereof

Abstract

The present invention relates to the technical field of medical accelerators, and discloses a medical accelerator, comprising an accelerating tube, a beam pipe, a beam scraper, a bellows and a beam needle, wherein the beam pipe, the beam scraper, the bellows and the beam needle are connected in sequence, and the four share a central axis and are connected to form a straight line channel for electron beams to be transmitted in the straight line channel; the inner aperture of the beam scraper is smaller than the inner aperture of the beam pipe. A dose monitoring system is also disclosed, comprising a resistor, a voltmeter, a wire and a data processing system, wherein the beam scraper, the resistor and the ground are connected in sequence through a wire, and the voltmeter is used to test the voltage value at both ends of the resistor; the data processing system processes the voltage value to obtain the dose of the electron beam. A dose monitoring method is also disclosed. The present invention generates a current through a part of the electron beam, synchronously tests the voltage at both ends of the resistor, obtains the dose rate of the electron beam by testing the voltage value, does not affect the treatment process, and can realize online monitoring of the dose of the electron beam.

Description

Technical Field

[0001] The present invention relates to the technical field of medical accelerators, and in particular to a medical accelerator, a dose monitoring system and a dose monitoring method. 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 system and a monitoring method for the medical accelerator with a small field electron beam that can monitor the dose online during the 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, a beam scraper, a bellows 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 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; the beam pipe, the beam scraper, the bellows and the beam needle are detachably connected in sequence, and the four 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 inner aperture of the beam scraper is smaller than the inner aperture of the beam pipe.

[0007] Preferably, the beam scraper is a cylinder with a central hole.

[0008] Preferably, the beam scraper is made of lead.

[0009] Preferably, the interior of the cylinder comprises an inner ring.

[0010] Preferably, the material of the inner ring is solid water or graphite.

[0011] Preferably, the bellows comprises an elastic channel tube, two flanges and at least three sets of bolts.

[0012] Preferably, the shape of the elastic channel tube can be adjusted by adjusting the position of the nut in the bolt.

[0013] Preferably, the outlet end of the beam needle is a sealed end.

[0014] The present invention also provides a dose monitoring system, comprising a resistor, a voltmeter, a wire and a data processing system, wherein the beam scraper, the resistor and the ground are connected in sequence through the wire, the voltmeter is used to test the voltage value at both ends of the resistor; the data processing system processes the voltage value to obtain the dose of the electron beam.

[0015] Preferably, the resistance value of the resistor is 50Ω-2000Ω.

[0016] The present invention also provides a method for measuring the dose monitoring of a medical accelerator of any of the above technical solutions, comprising the following steps:

[0017] S1: The first electron beam moves directionally between the beam scraper and the wire to generate current;

[0018] S2: The voltage value U at both ends of the resistor tested by the voltmeter;

[0019] S3: The data processing system further processes the voltage value U data to obtain the dose H of the second electron beam passing through the exit end of the beam needle.

[0020] Preferably, in step S3, there is a linear numerical relationship between the dose rate H of the second electron beam and the voltage value U: H=KU.

[0021] Preferably, the steps for determining the K value are as follows:

[0022] P1: The first electron beam moves directionally between the beam scraper and the wire to generate current; the second electron beam passes through the beam needle;

[0023] P2: The voltmeter tests the voltage value U1 at both ends of the resistor; the standard dosimeter tests the dose H1 at the exit end of the beam needle;

[0024] P3: Repeat steps P1-P2 to obtain a series of voltage values ​​U (U2, U3, U4, U i ,┉) and the dose rate H(H2,H3,H4,H i ,┉);

[0025] P4: The voltage value U (U1, U2, U3, U4, U i ,┉) and the dose rate H(H1,H2,H3,H4,H i ,┉) take the average value to get the average voltage value and the average dose rate of the second electron beam , we get a linear numerical relationship: , that is, the value of K is obtained.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The first electron beam moves in a directional manner between the beam scraper and the wire to generate current, and the voltage at both ends of the resistor is tested synchronously. The dose rate of the second electron beam is obtained by testing the voltage value. This method is novel.

[0028] 2. The dose value of the second electron beam is obtained by performing voltage synchronization test on the resistor and processing it through the data processing system. This process does not affect the treatment process and can monitor the dose online, thus improving the convenience and accuracy of treatment.

[0029] 3. Only one K value needs to be determined before treatment to achieve continuous and multiple monitoring of the treatment process, which is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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.

[0031] Figure 1 This is a basic structural block diagram of the medical accelerator of this application;

[0032] Figure 2 A schematic diagram of the structure of an accelerating tube, a beam needle and a dose monitoring system in a medical accelerator in one embodiment;

[0033] Figure 3 is a cross-sectional view of a beam scraper in one embodiment;

[0034] Figure 4 is a cross-sectional view of a beam scraper in another embodiment;

[0035] Figure 5This is a schematic diagram of the structure of a bellows in one embodiment;

[0036] Figure 6 For use Figure 2 Diagram of the steps of the dose monitoring method using a dose monitoring system;

[0037] Figure 7 A schematic diagram of the arrangement of a dose detection system when determining a K value in an embodiment;

[0038] Figure 8 A diagram showing the steps for determining the K value;

[0039] Figure numerals: 1-medical accelerator, 2-electron gun control power supply, 3-electron gun, 4-accelerating tube, 5-magnetron, 6-modulator, 7-beam pipe, 8-beam scraper, 801-center hole, 9-bellows, 10-beam needle, 11-elastic channel tube, 12-flange, 13-bolt, 14-resistance, 15-voltmeter, 16-data processing system, 17-standard dosimeter. DETAILED DESCRIPTION

[0040] 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.

[0041] It should be noted that the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. The term "front end" or "exit end" refers to the end close to the beam needle tip when the device or equipment of the present application is facing the reader; the "rear end" or "inlet end" refers to the end away from the beam needle tip when the device or equipment of the present application is facing the reader.

[0042] The present invention provides a medical accelerator 1, please refer to Figure 1-2, 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, a beam scraper 8, a bellows 9 and a beam needle 10; 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 10; 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 beam pipe 7, the beam scraper 8, the bellows 9 and the beam needle 10 are connected in sequence, and the four 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 inner aperture of the beam scraper 8 is smaller than the inner aperture of the beam pipe 7.

[0043] The treatment process of the present invention is as follows: the beam needle 10 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 10. The electron beam hits the tumor lesion site to ablate the tumor.

[0044] 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 10 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 10. The electron beam hits the tumor lesion site to ablate the tumor.

[0045] 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.

[0046] In order to enable the electron beam to be smoothly transmitted from the beam needle 10 , a focusing coil is arranged on the periphery of the connection structure between the accelerating tube 4 and the beam needle 10 , which is beneficial to effectively guide the movement path of the electron beam and ensure that the electron beam is focused on the axis of the beam needle 10 .

[0047] For further information, please refer to Figure 3-4 The beam scraper 8 is a cylinder with a central hole 801.

[0048] Furthermore, the beam scraper 8 is made of lead.

[0049] For further information, please refer to Figure 4 , the interior of the cylinder contains an inner ring.

[0050] Furthermore, the material of the inner ring is solid water or graphite.

[0051] For further information, see Figure 5 The bellows 9 includes an elastic channel tube 11 , two flanges 12 and at least three groups of bolts 13 .

[0052] Furthermore, the shape of the elastic channel tube 11 can be adjusted by adjusting the position of the nut in the bolt 13. For example, by shortening the distance between the nut and the bolt head at a certain position, the elastic channel tube 11 can be offset to the position.

[0053] Furthermore, the outlet end of the beam needle 10 is a sealed end.

[0054] 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.

[0055] In this embodiment, 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 electron attenuation degree is lighter. At this time, both the effective electron passing rate and the sealing of the space inside the tube can be guaranteed.

[0056] The present invention also provides a dose monitoring system, please refer to Figure 2 , including a resistor 14, a voltmeter 15, a wire and a data processing system 16. The beam scraper 8, the resistor 14 and the ground are connected in sequence through the wire. The voltmeter 15 is used to test the voltage value at both ends of the resistor 14; the data processing system 16 processes the voltage value to obtain the dose of the electron beam.

[0057] Preferably, the resistance value of the resistor 14 is 50Ω-2000Ω.

[0058] Specifically, the wire is directly connected to the beam scraper, for example, one end of the wire is wrapped around any part of the beam scraper, or the wire is welded to any part of the beam scraper. It is understandable that this embodiment is not limited to the above connection method, as long as the current on the beam scraper can be transmitted to the wire.

[0059] The present invention generates current by directionally moving the first electron beam between the beam scraper 8 and the wire, and synchronously tests the voltage across the resistor 14. The dose rate of the second electron beam is obtained by testing the voltage value, which does not affect the treatment process and can realize online monitoring of the dose of the second electron beam.

[0060] The present invention also provides a method for measuring the dose of the medical accelerator 1 of any of the above technical solutions, see Figure 6 , including the following steps:

[0061] S1: The first electron beam moves directionally between the beam scraper 8 and the wire to generate current;

[0062] S2: The voltmeter 15 tests the voltage value U across the resistor 14;

[0063] S3: the data processing system 16 further processes the voltage value U data to obtain the dose H of the second electron beam passing through the exit end of the beam needle 10 .

[0064] Furthermore, in step S3, there is a linear numerical relationship between the dose rate H of the second electron beam and the voltage value U: H=KU.

[0065] The dose monitoring method is used to indirectly obtain the dose of the second electron beam used for treatment by monitoring the first electron beam during treatment.

[0066] Figure 7 Schematic diagram of the arrangement of the dose detection system when determining the K value in one embodiment.

[0067] For further information, please refer to Figure 8 , the steps for determining the K value are as follows:

[0068] P1: The first electron beam moves directionally between the beam scraper 8 and the wire to generate current; the second electron beam passes through the beam needle 10;

[0069] P2: The voltmeter 15 tests the voltage value U1 at both ends of the resistor 14; the standard dose meter 17 tests the dose H1 at the exit end of the beam needle 10;

[0070] P3: Repeat steps P1-P2 to obtain a series of voltage values ​​U (U2, U3, U4, U i ,┉) and the dose rate H(H2,H3,H4,H i ,┉);

[0071] P4: The voltage value U (U1, U2, U3, U4, U i ,┉) and the dose rate H(H1,H2,H3,H4,H i ,┉) take the average value to get the average voltage value and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K is obtained.

[0072] The step of determining the K value is equivalent to establishing a mathematical relationship between the voltage value U and the dose rate H of the second electron beam, and needs to be performed before treatment.

[0073] Specifically, the standard dosimeter 17 of this embodiment is preferably a UNIDOS E dosimeter produced by PTW of Germany. The UNIDOS E dosimeter can test the signal at the exit of the beam needle 10 and directly obtain the dose of the second electron beam.

[0074] The principle of measuring absorbed dose by standard dosimeter 17 is: firstly measure the ionizing charge generated by ionizing radiation, then use the average ionizing energy of air to calculate and convert it into the energy deposited by ionizing radiation, i.e. absorbed dose.

[0075] In order to reduce the error of the dose test result, the distance between the standard dose meter 17 and the exit end of the beam needle 10 is equal and kept constant.

[0076] The present invention generates current by directionally moving part of the electron beam between the beam scraper 8 and the wire, and synchronously tests the voltage across the resistor 14. The dose rate of the electron beam is obtained by testing the voltage value, which does not affect the treatment process, can realize online monitoring of the electron beam dose, and improves the convenience and accuracy of treatment.

[0077] Example 1

[0078] Before treatment, the above steps P1-P4 were followed, the resistance value of the resistor was 50Ω, and the test data were shown in Table 1.

[0079] Table 1 Test results of U and H before treatment

[0080]

[0081] By processing the test results of U and H, K=1.597 is obtained.

[0082] Example 2

[0083] During the treatment process, dose monitoring is performed according to steps S1-S3. The test value of voltage U and the calculated value of dose rate H of the second electron beam are shown in Table 2.

[0084] Table 2 Test results of U and H during treatment

[0085]

[0086]

[0087] In this embodiment, the voltage of the first electron beam is monitored to calculate the dose rate of the second electron beam (used for treatment), and the dose rate monitoring is implemented without affecting the treatment.

[0088] The present invention generates current by directionally moving the first electron beam between a beam scraper and a wire, and synchronously tests the voltage at both ends of a resistor. The dose rate of the electron beam is obtained by testing the voltage value without affecting the treatment process. The dose of the second electron beam can be monitored online, thereby improving the convenience and accuracy of treatment.

[0089] 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, a beam scraper, a bellows 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; the beam pipe, the beam scraper, the bellows and the beam needle are detachably connected in sequence, and The four 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 inner aperture of the beam scraper is smaller than the inner aperture of the beam pipe; the beam scraper is used to transmit the first electron beam moving in a direction to the wire connected to the beam scraper, so as to test the voltage value U generated at both ends of the resistor connected to the beam scraper through the wire when the first electron beam moves in a direction between the beam scraper and the wire through a voltmeter connected to the wire, and further process the voltage value U data through a data processing system to obtain the dose H of the second electron beam passing through the exit end of the beam needle; There is a linear numerical relationship between the dose rate H of the second electron beam and the voltage value U: H=KU; And, the steps for determining the K value are as follows: P1: The first electron beam moves directionally between the beam scraper and the wire to generate current; the second electron beam passes through the beam needle; P2: The voltmeter tests the voltage value U1 at both ends of the resistor; the standard dosimeter tests the dose H1 at the exit end of the beam needle; P3: Repeat steps P1-P2 to obtain a series of voltage values ​​U (U2, U3, U4, U i ,┉) and the dose rate H(H2,H3,H4,H i ,┉); P4: The voltage value U (U1, U2, U3, U4, U i ,┉) and the dose rate H(H1,H2,H3,H4,H i ,┉) take the average value to get the average voltage value and the average dose rate of the second electron beam Get the linear numerical relationship: That is, the value of K is obtained.

2. The medical accelerator according to claim 1, characterized in that: The beam scraper is a cylinder with a central hole.

3. The medical accelerator according to claim 2, characterized in that: The beam scraper is made of lead.

4. The medical accelerator according to claim 2, characterized in that: The interior of the cylinder includes an inner ring.

5. The medical accelerator according to claim 4, characterized in that: The material of the inner ring is solid water or graphite.

6. The medical accelerator according to claim 1, characterized in that: The bellows comprises an elastic channel tube, two flanges and at least three groups of bolts.

7. The medical accelerator according to claim 6, characterized in that: The shape of the elastic channel tube can be adjusted by adjusting the position of the nut in the bolt.

8. The medical accelerator according to claim 1, characterized in that: The outlet end of the beam needle is a sealed end.

9. A dose monitoring system, characterized in that: It includes a resistor, a voltmeter, a wire and a data processing system. The beam scraper, the resistor and the ground are connected in sequence through the wire. The voltmeter is used to test the voltage value at both ends of the resistor. The data processing system processes the voltage value to obtain the dose of the electron beam. Wherein, the beam scraper is located in a medical accelerator, and the medical accelerator is the medical accelerator according to any one of claims 1 to 8.

10. The dose monitoring system according to claim 9, characterized in that: The resistance value of the resistor is 50Ω-2000Ω.

11. A dose monitoring method for measuring the medical accelerator according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: The first electron beam moves directionally between the beam scraper and the wire to generate current; S2: The voltage value U at both ends of the resistor tested by the voltmeter; S3: The data processing system further processes the voltage value U data to obtain the dose H of the second electron beam passing through the exit end of the beam needle; The medical accelerator comprises an electron gun control power supply, an electron gun, an accelerating tube, a magnetron, a modulator, a beam pipe, a beam scraper, a bellows 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; the beam pipe, the beam scraper, the bellows and the beam needle are detachable in sequence The beam scraper is connected to the beam scraper, and the four 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 inner aperture of the beam scraper is smaller than the inner aperture of the beam pipe; the beam scraper is used to transmit the first electron beam moving in a direction to the wire connected to the beam scraper, so as to test the voltage value U generated at both ends of the resistor connected to the beam scraper through the wire when the first electron beam moves in a direction between the beam scraper and the wire through a voltmeter connected to the wire, and further process the voltage value U data through a data processing system to obtain the dose H of the second electron beam passing through the exit end of the beam needle; Furthermore, the beam scraper, the resistor and the ground are sequentially connected through the wire, and the voltmeter is used to test the voltage value at both ends of the resistor; The data processing system processes the voltage value to obtain the dose of the electron beam.

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