Beam energy monitoring method and beam control method of ion therapy device

Abstract

The present disclosure provides a beam energy monitoring method and a beam control method for an ion therapy device, wherein the beam energy monitoring method comprises: measuring the first magnetic field strength or the first current of the accelerator deflection dipole magnet of the ion therapy device, and calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the first current; or measuring the second magnetic field strength or the second current of the transmission line deflection dipole magnet; and calculating the actual beam energy output by the ion therapy device according to the second magnetic field strength or the second current. The method accurately calculates the beam energy according to the magnetic field or the current of the accelerator dipole magnet measured in the embodiment, realizes the real-time online monitoring of the beam energy, overcomes the problem that the accuracy and stability of the accelerator energy cannot be directly verified, and when applied to a treatment terminal or an experimental terminal, can realize the energy interlocking function, ensure the accuracy and stability of the ion accelerator energy, and make the treatment more accurate, safer and more efficient.

Description

Technical Field

[0001] The present disclosure relates to the technical field of particle therapy and proton and heavy ion radiotherapy, and in particular to a beam energy monitoring method and a beam control method for an ion therapy device. Background Art

[0002] When an ion beam passes through a substance, its kinetic energy is mainly lost at the end of the range, and a sharply enhanced Bragg peak will appear. That is, when ions interact with substances, the energy is mainly lost within the millimeter range at the end of the range, and the position of the Bragg peak of the ion beam is highly precisely controllable. By utilizing these characteristics, energy can be deposited in the patient's tumor target area to the greatest extent, thereby enhancing the local control rate of the tumor and reducing the risk of complications in normal tissues. Therefore, ion beam radiotherapy has advantages that are difficult to match with conventional radiotherapy methods, such as unique deep dose distribution and higher relative biological effect.

[0003] The range of ions in tissue or water is determined by the ion energy per nucleon (MeV / u), and ion therapy requires that the ion Bragg peak accurately falls on the tumor target area. Therefore, the accuracy and stability of the energy (range) during ion therapy determines the precision of ion therapy.

[0004] The existing method to ensure the range is to regularly verify the range before daily treatment, usually based on the quality assurance (QA) test range. The test generation method includes: using a three-dimensional water tank, ionization chamber, electrometer and other equipment to measure the high-energy particle depth dose distribution curve, and measuring the corresponding peak value from the curve to determine its range, or using a peak detector (PTW PEAKFINDER) to verify the peak position of the energy, or using a Bragg peak detector to verify the peak position of the energy.

[0005] However, the existing verification methods have large human errors, and the positioning errors of various instruments and equipment are difficult to improve. There are errors such as the dead zone of the ionization chamber, the wall thickness of the water tank, and the gap dead zone caused by the placement error, resulting in low accuracy in the verification of the energy accuracy and stability of the ion accelerator. This energy verification method may cause serious medical accidents when applied to treatment devices. When applied to scientific research, it will cause experimental data errors, experimental failures and other consequences, and the experimental research cannot be completed. In addition, the guarantee of the range stability of existing ion treatment devices can only be confirmed by QA before treatment. If all energies are measured and verified during QA, it will take a lot of time for QA, resulting in reduced treatment efficiency. Summary of the invention

[0006] In view of the above technical problems, the present disclosure provides a beam energy monitoring method and a beam control method for an ion therapy device, which are used to at least partially solve the technical problems such as low energy accuracy and stability verification precision of ion accelerators caused by existing energy verification methods.

[0007] Based on this, the first aspect of the present disclosure provides a beam energy monitoring method for an ion therapy device, including: directly measuring the first magnetic field strength of an accelerator deflection dipole magnet or the second magnetic field strength of a transmission line deflection dipole magnet of the ion therapy device; and calculating the actual beam energy output by the ion therapy device based on the first magnetic field strength or the second magnetic field strength.

[0008] According to an embodiment of the present disclosure, the first magnetic field strength of the accelerator deflection dipole magnet of the ion therapy device or the second magnetic field strength of the transmission line deflection dipole magnet is measured by the Hall effect method or the nuclear magnetic resonance method.

[0009] According to an embodiment of the present disclosure, calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength includes:

[0010]

[0011] Calculate the actual beam kinetic energy E k , where B is the first magnetic field strength or the second magnetic field strength, ρ is the curvature radius of the beam deflection, Z is the charge number of the charged particles forming the beam, A is the mass number of the charged particles, and E0 is the energy of a single nucleon at rest.

[0012] A second aspect of the present disclosure provides a beam control method for an ion therapy device, comprising: directly measuring a first magnetic field strength of an accelerator deflection dipole magnet of the ion therapy device or a second magnetic field strength of a transmission line deflection dipole magnet; calculating an actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength; in response to an error between the actual beam energy and a preset beam energy of the ion therapy device being within a preset range, controlling the ion therapy device to output a beam of the actual beam energy; and in response to an error between the actual beam energy and the preset beam energy of the ion therapy device exceeding the preset range, controlling the ion therapy device to cut off beam extraction.

[0013] A third aspect of the present disclosure provides a beam energy monitoring method for an ion therapy device, comprising: measuring a first current output by an accelerator deflection dipole magnet power supply of the ion therapy device or a second current output by a transmission line deflection dipole magnet power supply; based on an excitation curve, calculating a first magnetic field strength of the accelerator deflection dipole magnet corresponding to the first current based on the first current, and calculating a second magnetic field strength of the transmission line deflection dipole magnet corresponding to the second current based on the second current; and calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength.

[0014] According to an embodiment of the present disclosure, calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength includes:

[0015]

[0016] Calculate the actual beam kinetic energy E k , where B is the first magnetic field strength or the second magnetic field strength, ρ is the curvature radius of the beam deflection, Z is the charge number of the charged particles forming the beam, A is the mass number of the charged particles, and E0 is the energy of a single nucleon at rest.

[0017] A fourth aspect of the present disclosure provides a beam control method for an ion therapy device, comprising: measuring a first current output by an accelerator deflection dipole magnet power supply of the ion therapy device or a second current output by a transmission line deflection dipole magnet power supply; based on an excitation curve, calculating a first magnetic field strength of the accelerator deflection dipole magnet corresponding to the first current based on the first current, and calculating a second magnetic field strength of the transmission line deflection dipole magnet corresponding to the second current based on the second current; calculating an actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength; in response to an error between the actual beam energy and a preset beam energy of the ion therapy device being within a preset range, controlling the ion therapy device to output a beam of the actual beam energy; in response to an error between the actual beam energy and the preset beam energy of the ion therapy device exceeding the preset range, controlling the ion therapy device to cut off beam extraction.

[0018] The beam energy monitoring method and beam control method of the ion therapy device provided by the embodiments of the present disclosure at least have the following beneficial effects:

[0019] The energy of the ion beam output by the accelerator is calculated by collecting the deflection magnetic field strength of the accelerator's dipole magnet or the magnitude of the current loaded on the accelerator's dipole magnet, or the energy of the accelerator reaching the treatment terminal or the experimental terminal is calculated by collecting the deflection dipole magnet magnetic field or current on the beam transmission line. This overcomes the problem of the existing method that the beam energy cannot be verified in real time, and also avoids the problem of low accuracy of accelerator energy and stability verification due to positioning errors.

[0020] Furthermore, when the ion therapy device beam energy monitoring method is applied to the treatment terminal or the experimental terminal, the magnetic field strength or current can be obtained in real time, and compared and fed back with the preset energy, the energy interlocking function is realized to ensure the accuracy and stability of the ion accelerator energy. Moreover, compared with the measurement and verification of all energies through QA before treatment, real-time monitoring and interlocking can be realized, making the treatment more accurate, safer and more efficient.

[0021] In addition, this method can also be used in experimental setups based on synchrotrons to ensure the accuracy of the experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0023] Figure 1 A flow chart of a beam energy monitoring method for an ion therapy device provided in an embodiment of the present disclosure is schematically shown.

[0024] Figure 2 The structure of an ion therapy device using a synchrotron as a main accelerator provided by an embodiment of the present disclosure is schematically shown.

[0025] Figure 3 The structure of an ion therapy device provided by an embodiment of the present disclosure using a cyclotron or a linear accelerator as a main accelerator is schematically shown.

[0026] Figure 4 A flow chart of a beam control method for an ion therapy device provided in an embodiment of the present disclosure is schematically shown.

[0027] Figure 5 A flow chart of a beam energy monitoring method for an ion therapy device provided in another embodiment of the present disclosure is schematically shown.

[0028] Figure 6 A flow chart of a beam control method for an ion therapy device provided in another embodiment of the present disclosure is schematically shown.

[0029] Figure 7 The relationship curve between the magnetic field strength of the deflection dipole magnet magnetic field and the calculated energy provided by the embodiment of the present disclosure is schematically shown.

[0030] Figure 8 The relationship curve between the magnetic field strength and the current value of the deflection dipole magnet magnetic field provided by the embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

[0032] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0033] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0034] In the description of the present disclosure, it is necessary to understand that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0035] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure. The shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual size, proportion, and actual positional relationship. In addition, in the claims, any reference symbol between brackets shall not be construed as a limitation to the claims.

[0036] Similarly, in order to simplify the present disclosure and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present disclosure, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] Figure 1 A flow chart of a beam energy monitoring method for an ion therapy device provided in an embodiment of the present disclosure is schematically shown.

[0039] like Figure 1 As shown, the beam energy monitoring method of the ion therapy device may include, for example, operations S101 to S102.

[0040] In operation S101 , a first magnetic field strength of an accelerator deflection dipole magnet of an ion therapy device or a second magnetic field strength of a transmission line deflection dipole magnet is directly measured.

[0041] In operation S102, actual beam energy output by the ion therapy apparatus is calculated according to the first magnetic field strength or the second magnetic field strength.

[0042] The present disclosure embodiment adopts Figure 1 The reasons for the beam energy monitoring method of the ion therapy device shown may be specifically as follows:

[0043] Figure 2 The structure of an ion therapy device using a synchrotron as a main accelerator provided by an embodiment of the present disclosure is schematically shown.

[0044] like Figure 2 As shown, in a synchrotron, particles move in a closed orbit under the action of the magnetic field of a deflection dipole magnet. As the particle energy increases, the deflection magnetic field and the high-frequency electric field frequency of the accelerated particles also increase synchronously, so that the resonant acceleration of the particles on a fixed orbit can be maintained. This accelerator is called a synchrotron. Based on this, in the process of realizing the concept of the present invention, the applicant discovered that: for particles of the same energy, the deflection magnetic field strength is fixed and there is a one-to-one correspondence with the particle energy. Therefore, in an ion therapy system with a synchrotron as the main accelerator, this feature of the synchrotron can be used to measure the magnetic field strength of the synchrotron dipole magnet or the current loaded by the synchrotron dipole magnet, and calculate the corresponding ion energy, thereby achieving real-time measurement of the energy of the ion therapy device.

[0045] Similarly, the particles transmitted on the transmission line of the ion therapy device must maintain their deflection angle in the deflection magnet unchanged in order to be transmitted to the terminal, and the deflection angle and the magnetic field of the magnet are in a one-to-one correspondence. Therefore, the monitoring of the ion beam energy output by the accelerator can also be achieved by collecting the magnetic field strength of the deflection magnet on the transmission line.

[0046] Figure 3 The structure of an ion therapy device provided by an embodiment of the present disclosure using a cyclotron or a linear accelerator as a main accelerator is schematically shown.

[0047] like Figure 3 As shown, a deflection dipole magnet is also installed on the transmission line from the main accelerator to the terminal. Figure 2 The same analysis shows that the energy of the ion beam output by the accelerator can also be monitored by collecting the magnetic field strength or method of the deflection magnet on the transmission line.

[0048] Therefore, based on Figure 2 and Figure 3 It can be known from the related analysis that the beam energy can be calculated by directly measuring the first magnetic field strength of the accelerator deflection dipole magnet of the ion therapy device or the second magnetic field strength of the transmission line deflection dipole magnet.

[0049] In one embodiment of the present disclosure, the Hall effect method or the nuclear magnetic resonance method is used to measure the first magnetic field strength of the accelerator deflection dipole magnet of the ion therapy device or the second magnetic field strength of the transmission line deflection dipole magnet.

[0050] In the field of magnetic field measurement, according to different basic physical principles, magnetic field measurement methods may include Hall effect method, nuclear magnetic resonance method, flux method, fluxgate method, optical pump method, magneto-optical effect method, superconducting quantum interference device method, etc. These methods are applied to different measurement fields according to the intensity and resolution of the measured magnetic field.

[0051] By analyzing the magnetic field values ​​of the accelerator magnet, it is found that the magnetic field values ​​of the accelerator magnet generally range from 10 -2 -10 1 Within Tesla (T), the resolution is about 10 -6 -10 -4 Tesla (T), based on this, the present disclosure selects the Hall effect method or the nuclear magnetic resonance method to measure the magnetic field. The advantages of magnetic measurement equipment based on magnetic resonance include: high absolute measurement accuracy of magnetic field, less than 1ppm; zero temperature coefficient, not affected by ambient temperature; the size of the measured value is independent of the direction of the magnetic field. The advantages of using Hall probes to measure magnetic fields include: small size, suitable for measuring small air gaps and complex geometric magnets; relatively cheap price; no contacts, no moving parts, good mechanical properties, long service life; wide measurement range, 10-5 -10 5 T continuous measurement; small effective area, the minimum can reach 50μm*50μm, suitable for measuring inhomogeneous fields; can be used at low temperatures; fast measurement speed; high measurement accuracy, up to 0.1mGs.

[0052] In one embodiment of the present disclosure, calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength includes:

[0053] according to

[0054]

[0055] Calculate the actual beam kinetic energy E k , where B is the first magnetic field strength or the second magnetic field strength, ρ is the curvature radius of the beam deflection, Z is the charge number of the charged particles forming the beam, A is the mass number of the charged particles, and E0 is the energy of a single nucleon at rest.

[0056] For example, in accelerator physics, a beam is defined as a flow of charged particles formed when a large number of charged particles move in a certain direction under the action of an electromagnetic field. The beam energy usually refers to the kinetic energy of the beam. That is, the present disclosure needs to calculate the kinetic energy of the beam.

[0057] The basic principle of the circular motion of charged particles in the deflection magnetic field is that the centripetal force is equal to the Lorentz force, that is:

[0058]

[0059] Among them, m is the mass of the particle, v is the tangential motion velocity of the particle, ρ is the radius of curvature of the beam deflection, Z is the charge number of the charged particles forming the beam, and e is the unit charge.

[0060] Based on the above formula, the momentum of the particle can be obtained as:

[0061] P=mv=ZeBρ=ZeG

[0062] Here, G is defined as the magnetic stiffness of particle motion, with the unit of T×m.

[0063] Since the beam is a high-speed particle, the relativistic effect needs to be considered. The relativistic factors are β and γ. The relationship is as follows:

[0064]

[0065]

[0066]

[0067] mc 2=γm0c 2

[0068] Where c is the speed of light, c = 299792458 m / s. m0 is the static mass of the particle.

[0069] And because:

[0070] m0c 2 =γm′0c 2

[0071] Among them, m′0 is the static mass of each nucleon, and E0 is the energy of a single nucleon at rest, which is:

[0072] E0=m′0c 2 =931.494MEV / u

[0073] Substituting the speed of light c and E0 into the above formula, we can get:

[0074]

[0075] Then we can get:

[0076]

[0077] Based on the above formula, the kinetic energy of the beam can be calculated according to the magnetic field.

[0078] based on Figure 1 The beam energy monitoring method shown provides a beam control method for an ion therapy device.

[0079] Figure 4 A flow chart of a beam control method for an ion therapy device provided in an embodiment of the present disclosure is schematically shown.

[0080] like Figure 4 As shown, the beam control method of the ion therapy device may include, for example, operations S401 to S404. Operations S401 and S402 are respectively the same as operations S101 and S102, and the specific details are not repeated here.

[0081] In operation S403, in response to an error between the actual beam energy and a preset beam energy of the ion therapy apparatus being within a preset range, the ion therapy apparatus is controlled to output a beam with the actual beam energy.

[0082] In operation S404, in response to an error between the actual beam energy and a preset beam energy of the ion therapy apparatus exceeding a preset range, the ion therapy apparatus is controlled to cut off beam extraction.

[0083] Exemplarily, the beam control method obtains the preset energy required for treatment from the treatment control system server and sets the allowable error range. When the treatment control system applies for the beam and the accelerator starts working, the energy verification system is started to collect the magnetic field strength of the dipole magnet in real time and calculate the actual energy, which is compared with the preset energy. If the energy error is outside the allowable range, a chain signal is sent to immediately cut off the beam extraction; if the energy error is within the allowable range, beam delivery treatment can be performed.

[0084] According to the embodiment of the present disclosure, since the magnetic field range of the dipole magnet is generally 10 -1 -10 1 Within Tesla (T), the current magnetic measuring device has high measurement accuracy, so it is possible to verify the energy by collecting the deflection magnetic field strength of the dipole magnet and realize the energy chain of the treatment device, ensuring that the energy output of the experimental device meets the experimental requirements and ensuring the range accuracy and range stability during the ion accelerator treatment process.

[0085] Figure 5 A flow chart of a beam energy monitoring method for an ion therapy device provided in another embodiment of the present disclosure is schematically shown.

[0086] like Figure 5 As shown, the beam energy monitoring method of the ion therapy device may include, for example, operations S501 to S503.

[0087] In operation S501, a first current outputted by an accelerator deflection dipole magnet power supply of an ion therapy apparatus or a second current outputted by a transmission line deflection dipole magnet power supply is measured.

[0088] In operation S502 , based on the excitation curve, a first magnetic field strength of the accelerator deflection dipole magnet corresponding to the first current is calculated based on the first current, and a second magnetic field strength of the transmission line deflection dipole magnet corresponding to the second current is calculated based on the second current.

[0089] In operation S503, actual beam energy output by the ion therapy device is calculated according to the first magnetic field strength or the second magnetic field strength.

[0090] The present disclosure embodiment adopts Figure 5 The reasons for the beam energy monitoring method of the ion therapy device shown may be specifically as follows:

[0091] Please continue reading Figure 2 and Figure 3For particles with the same energy, the deflection magnetic field strength is fixed and has a one-to-one correspondence with the particle energy. The magnetic field strength of the deflection magnet and the current loaded by the magnet also have a one-to-one correspondence. This feature of the synchrotron accelerator can be used to measure the current loaded by the accelerator dipole magnet or the transmission line dipole magnet, and calculate the corresponding ion energy, thereby realizing real-time measurement of the energy of the ion therapy device.

[0092] In one embodiment of the present disclosure, the measurement of current can be divided into two categories: direct measurement and indirect measurement. Direct measurement refers to determining the magnitude of the measured current based on the voltage of the measured current on a known resistor, such as a shunt. Indirect measurement, based on the magnetic field established by the measured current, measures the current by measuring magnetic density, magnetic flux or magnetic potential.

[0093] Common current sensors include shunts, zero flux current transformers, Hall current sensors, and optical current sensors. The performance of different current sensors is shown in Table 1 below:

[0094] Table 1

[0095] Current Sensors Accuracy Range Shunt ≤0.1 ≤10kA Magnetic modulation ≤0.01 0-100kA Magnetic Amplifier ≤0.1 0-10kA Hall Effect ≤0.1 0-40kA Optical Sensors ≤0.1 0-10kA

[0096] It should be noted that the excitation curve is obtained when the accelerator device magnet performs magnetic field measurement. After the measured current value is converted into magnetic field intensity through the excitation curve, the beam side method is calculated based on the magnetic field intensity. Figure 1 The method shown is the same and will not be repeated here.

[0097] based on Figure 5 In addition to the beam energy monitoring method shown, the disclosed embodiment also provides a beam control method for an ion therapy device.

[0098] Figure 6 A flow chart of a beam control method for an ion therapy device provided in another embodiment of the present disclosure is schematically shown.

[0099] like Figure 6 As shown, the beam control method of the ion therapy device may include, for example, operations S601 to S605. Operations S601 and S603 are respectively the same as operations S501 and S502, and the specific details are not repeated here.

[0100] In operation S604, in response to an error between the actual beam energy and a preset beam energy of the ion therapy apparatus being within a preset range, the ion therapy apparatus is controlled to output a beam with the actual beam energy.

[0101] In operation S605 , in response to an error between the actual beam energy and a preset beam energy of the ion therapy apparatus exceeding a preset range, the ion therapy apparatus is controlled to cut off beam extraction.

[0102] Since the current range of the diode magnet power supply is generally 10 2 -10 4 At present, the current measuring device has high measurement accuracy, so it is possible to verify the energy by collecting the accelerator diode magnet power supply current and realize the energy chain of the treatment device, ensuring that the energy output of the experimental device meets the experimental requirements and ensuring the range accuracy and range stability during the ion accelerator treatment process.

[0103] In order to further illustrate the advantages of the beam energy monitoring method and the beam control method of the ion therapy device provided by the embodiment of the present disclosure, the embodiment of the present disclosure also provides a typical case to demonstrate the feasibility of the present disclosure, as follows:

[0104] The main accelerator of the existing carbon ion therapy system is a synchrotron. The circumference of the synchrotron is L = 56.1727m, and the accelerated ions are carbon ions. 12 C 6+ The single nucleon energy of the ion is 931.5MeV / u, and the energy range is 120MeV / u-400MeV / u.

[0105] The basic parameters of the synchrotron are shown in Table 2:

[0106] Table 2

[0107]

[0108]

[0109] The parameters of the deflection dipole magnet of the synchrotron are shown in Table 3:

[0110] Table 3

[0111]

[0112] The deflection dipole magnet power supply parameters of the synchrotron are shown in Table 4:

[0113] Table 4

[0114]

[0115] The bending radius of the synchronous ring dipole magnet of the carbon ion therapy system is 4 meters. 12 C 6+ Particles, based on these parameters, can calculate the relationship between typical energy and magnetic field

[0116] The corresponding relationship between uniform scanning energy and magnetic field is shown in Table 5 below:

[0117] Table 5

[0118] Ek(MeV / u) B(T) 120 0.815802264 190 1.044368496 260 1.242215762 330 1.422222439 400 1.590457656

[0119] The corresponding relationship between the modulation scanning energy and the magnetic field is shown in Table 6 below:

[0120] Table 6

[0121]

[0122]

[0123]

[0124] Figure 7 The relationship curve between the magnetic field strength of the deflection dipole magnet magnetic field and the calculated energy provided by the embodiment of the present disclosure is schematically shown.

[0125] like Figure 7 As shown, the beam energy increases monotonically with the increase of the magnetic field strength of the dipole magnet magnetic field.

[0126] The relationship between the current value loaded by the diode iron of the carbon ion therapy system and its magnetic field strength can be obtained from the magnet excitation curve. The excitation curve is obtained by measurement, as shown in Table 7 below:

[0127] Table 7

[0128]

[0129]

[0130] Figure 8 The relationship curve between the magnetic field strength and the current value of the deflection dipole magnet magnetic field provided by the embodiment of the present disclosure is schematically shown.

[0131] like Figure 8 As shown, the magnetic field strength of the deflection dipole magnet magnetic field increases monotonically with the increase of the current value of the dipole magnet magnetic field.

[0132] Combining the aforementioned formula between magnetic stiffness and energy, the particle energy value can be calculated based on the above current data.

[0133] According to the technical requirements of the carbon ion therapy system, the accuracy of the range of the carbon ion beam during delivery, that is, the range difference: ≤±0.5mm water. The minimum energy adjustment step of the carbon ion therapy system is 2mm. From the above data, it can be seen that the energy is 120.26MeV / u to 399.92MeV / u, the energy deviation between adjacent energies is between 1.58MeV / u and 3.65MeV / u, the synchronous ring dipole magnet magnetic field strength deviation between adjacent energies is between 36.95GS and 130.59GS, and the synchronous ring dipole magnet power supply current deviation between adjacent energies is between 9.4A and 10.7A. When the range difference is 0.5mm, the synchronous ring dipole magnet magnetic field strength deviation is minimum 9.23GS, and the corresponding current deviation is minimum 2.35A. At present, the magnetic measuring device has high measurement accuracy, which can reach 0.1mGs, and the current measuring device has high measurement accuracy, which can reach 0.1A level, which meets the testing needs of the domestic carbon ion therapy system. Therefore, the beam energy monitoring method and control method of the ion therapy device provided by the present disclosure can achieve real-time monitoring of ion beam energy by collecting the deflection magnetic field strength of the synchronous ring dipole magnet or the power supply current of the synchronous ring dipole magnet, and realize energy interlocking on the treatment device to ensure the range accuracy and range stability of the domestic carbon ion therapy system during treatment. The same scheme of collecting the deflection dipole magnet magnetic field or current on the transmission line can also realize the function of energy verification.

[0134] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for monitoring beam energy of an ion therapy device, characterized in that: include: directly measuring the first magnetic field strength of the accelerator deflection dipole magnet or the second magnetic field strength of the transmission line deflection dipole magnet of the ion therapy device; Calculating actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength; The ion therapy device uses a synchrotron as a main accelerator; and calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength comprises: according to Calculate the kinetic energy E of the actual beam k , wherein B is the first magnetic field strength or the second magnetic field strength, ρ is the curvature radius of the beam deflection, Z is the charge number of the charged particles forming the beam, A is the mass number of the charged particles, and E0 is the energy of a single nucleon at rest.

2. The beam energy monitoring method according to claim 1, characterized in that: The first magnetic field strength of the accelerator deflection dipole magnet of the ion therapy device or the second magnetic field strength of the transmission line deflection dipole magnet is measured by the Hall effect method or the nuclear magnetic resonance method.

3. A beam control method for an ion therapy device, characterized in that: include: directly measuring the first magnetic field strength of the accelerator deflection dipole magnet or the second magnetic field strength of the transmission line deflection dipole magnet of the ion therapy device; Calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength; In response to an error between the actual beam energy and a preset beam energy of the ion therapy device being within a preset range, controlling the ion therapy device to output a beam with an actual beam energy; In response to an error between the actual beam energy and a preset beam energy of the ion therapy device exceeding the preset range, controlling the ion therapy device to cut off beam extraction; The ion therapy device uses a synchrotron as a main accelerator; and calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength comprises: according to Calculate the kinetic energy E of the actual beam k , wherein B is the first magnetic field strength or the second magnetic field strength, ρ is the curvature radius of the beam deflection, Z is the charge number of the charged particles forming the beam, A is the mass number of the charged particles, and E0 is the energy of a single nucleon at rest.

4. A method for monitoring beam energy of an ion therapy device, characterized in that: include: Measuring a first current output by a deflection dipole magnet power supply of an accelerator of the ion therapy device or a second current output by a deflection dipole magnet power supply of a transmission line; Based on the excitation curve, calculating the first magnetic field strength of the accelerator deflection dipole magnet corresponding to the first current based on the first current, and calculating the second magnetic field strength of the transmission line deflection dipole magnet corresponding to the second current based on the second current; Calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength; The ion therapy device uses a synchrotron as a main accelerator; and calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength comprises: according to Calculate the kinetic energy E of the actual beam k , wherein B is the first magnetic field strength or the second magnetic field strength, ρ is the curvature radius of the beam deflection, Z is the charge number of the charged particles forming the beam, A is the mass number of the charged particles, and E0 is the energy of a single nucleon at rest.

5. A beam control method for an ion therapy device, characterized in that: include: Measuring a first current output by a deflection dipole magnet power supply of an accelerator of the ion therapy device or a second current output by a deflection dipole magnet power supply of a transmission line; Based on the excitation curve, calculating the first magnetic field strength of the accelerator deflection dipole magnet corresponding to the first current based on the first current, and calculating the second magnetic field strength of the transmission line deflection dipole magnet corresponding to the second current based on the second current; Calculating actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength; In response to an error between the actual beam energy and a preset beam energy of the ion therapy device being within a preset range, controlling the ion therapy device to output a beam with the actual beam energy; In response to an error between the actual beam energy and a preset beam energy of the ion therapy device exceeding the preset range, controlling the ion therapy device to cut off beam extraction; The ion therapy device uses a synchrotron as a main accelerator; and calculating the actual beam energy output by the ion therapy device according to the first magnetic field strength or the second magnetic field strength comprises: according to Calculate the kinetic energy E of the actual beam k , wherein B is the first magnetic field strength or the second magnetic field strength, ρ is the curvature radius of the beam deflection, Z is the charge number of the charged particles forming the beam, A is the mass number of the charged particles, and E0 is the energy of a single nucleon at rest.

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