Design method and system for rfq accelerator for medical isotope production

Abstract

The application relates to the medical technology field and provides a design method and system of an RFQ accelerator for medical isotope production, wherein the design method comprises the following steps: determining a target working frequency range of the RFQ accelerator; based on the target working frequency range, optimizing structure parameters of the RFQ accelerator, determining an optimized dynamic design scheme of the RFQ accelerator; performing high-frequency design on the structure parameters of the RFQ accelerator, determining a high-frequency design scheme of the RFQ accelerator; optimizing structure parameters of a cooling flow channel in the RFQ accelerator, determining a physical design scheme of the RFQ accelerator, and obtaining the RFQ accelerator for medical isotope production. Through selection of the optimal working frequency range of the RFQ accelerator and optimization of the structure parameters of the RFQ accelerator under the optimal working frequency, the length of the RFQ accelerator can be shortened, the production cost can be reduced, and the transmission efficiency of an alpha beam can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the medical technology field, and in particular to a design method of an RFQ accelerator for medical isotope production and an ultra-high frequency normal-temperature linear accelerator system. BACKGROUND

[0002] Targeted alpha particle therapy (TAT) is one of the radioisotope targeted therapies. Compared with beta nuclides, alpha nuclides have larger mass number, shorter range, higher linear energy density in the biological body, and thus stronger cytotoxicity in the biological tissue. These characteristics enable alpha nuclides to show unique advantages in the treatment of hypoxic tumors, microtumors, scattered tumors and micrometastatic tumors. There are fewer alpha isotopes suitable for targeted therapy, one of which is 211 At, 211 At has appropriate half-life (T 1 / 2 = 7.2h); higher biological effect and radiation toxicity, causes irreversible damage to tumor cell DNA within its range of action; simple decay, only 2-level alpha decay, and no obvious recoil effect, and thus is considered to be a high-quality clinical targeted alpha particle therapy nuclide.

[0003] Currently, accelerators for producing isotopes include cyclotrons and linear accelerators. For cyclotrons, the average current is about tens of μA level, and the alpha beam is accelerated to 26-70 MeV, which requires a cyclotron diameter of about 3-8 m. The current of the cyclotron is low, thereby resulting in a low yield of isotopes.

[0004] Linear accelerators are mainly divided into superconducting linear accelerators and low-frequency normal-temperature linear accelerators. For superconducting linear accelerators, the acceleration gradient is high, and the average current can reach tens of mA level. However, in order to achieve a superconducting state, a cryostat is introduced, thereby resulting in a long overall length and high manufacturing and operating costs. For low-frequency normal-temperature linear accelerators, the average current can reach several mA level. However, due to the low working frequency, the acceleration gradient is low, and is usually 2-3 MV / m, the beam is accelerated to 28-30 MeV, and the acceleration part needs a length of about 12 m. In addition, the low working frequency will make the lateral size of the cavity large, thereby resulting in high manufacturing cost. SUMMARY

[0005] In view of the above problems, the present application aims to provide a design method of an RFQ accelerator for medical isotope production and an ultra-high frequency normal-temperature linear accelerator system, which can improve the beam transmission efficiency and reduce the production cost.

[0006] The present application provides a design method of an RFQ accelerator for medical isotope production, which comprises the following steps:

[0007] determining the target working frequency range of the RFQ accelerator;

[0008] optimizing structure parameters of the RFQ accelerator based on the target working frequency range, to determine first optimization parameters used for determining an optimized dynamic design scheme of the RFQ accelerator;

[0009] performing high-frequency design on the structure parameters of the RFQ accelerator based on the optimized dynamic design scheme, to determine second optimization parameters used for determining a high-frequency design scheme of the RFQ accelerator;

[0010] optimizing structure parameters of cooling flow channels in the RFQ accelerator based on the high-frequency design scheme, to obtain third optimization parameters used for determining a physical design scheme of the RFQ accelerator;

[0011] obtaining the RFQ accelerator for medical isotope production based on the physical design scheme.

[0012] According to the design method of the RFQ accelerator for medical isotope production provided by the application, the target working frequency range of the RFQ accelerator is determined, which comprises:

[0013] determining a stable working frequency range and a minimum aperture range corresponding to a transverse stability region boundary based on a transverse stability condition of the RFQ accelerator;

[0014] determining an optimal working frequency range from the stable working frequency range;

[0015] determining the optimal working frequency range as the target working frequency range.

[0016] According to the design method of the RFQ accelerator for medical isotope production provided by the application, the optimizing structure parameters of the RFQ accelerator based on the target working frequency range, to determine first optimization parameters, comprises:

[0017] determining a first key factor affecting a sparking coefficient of the RFQ accelerator based on the target working frequency range, and performing optimization design on the structure parameters of the RFQ accelerator based on the first key factor to obtain first initial optimization parameters;

[0018] determining a second key factor causing insufficient transverse focusing of the RFQ accelerator, and performing optimization design on the structure parameters of the RFQ accelerator based on the second key factor to obtain second initial optimization parameters;

[0019] determining a third key factor causing length overlong of the RFQ accelerator, and performing optimization design on the structure parameters of the RFQ accelerator based on the third key factor to obtain third initial optimization parameters;

[0020] determine a fourth key factor causing the beam transmission efficiency to be low, and design the structure parameters of the RFQ accelerator based on the fourth key factor to obtain fourth initial optimization parameters;

[0021] determine the fourth initial optimization parameters as the first optimization parameters.

[0022] According to the design method of the RFQ accelerator for medical isotope production provided by the application, based on the target working frequency range, a first key factor affecting the sparking coefficient of the RFQ accelerator is determined, and the structure parameters of the RFQ accelerator are designed based on the first key factor to obtain first initial optimization parameters, including:

[0023] determine the range of the Kilpatrick field corresponding to the target working frequency range based on the Kilpatrick criterion;

[0024] determine the maximum surface electric field range based on the preset value of the sparking coefficient of the RFQ accelerator and the range of the Kilpatrick field;

[0025] determine the inter-electrode voltage range corresponding to the maximum surface electric field range based on the relationship between the maximum surface electric field of the RFQ accelerator and the inter-electrode voltage;

[0026] determine the maximum surface electric field range and the inter-electrode voltage range as the first initial optimization parameters.

[0027] According to the design method of the RFQ accelerator for medical isotope production provided by the application, the second key factor causing the RFQ accelerator to be insufficient in lateral focusing is determined, and the structure parameters of the RFQ accelerator are designed based on the second key factor to obtain second initial optimization parameters, including:

[0028] determine the acceleration efficiency range based on formula (1) and formula (2);

[0029] B=eλ 2 XV / γM0c 2 a 2 (1)

[0030] X=1-AI0(ka)(2)

[0031] wherein A represents the acceleration efficiency, B represents the lateral focusing intensity, X represents the lateral focusing factor, a represents the minimum aperture, V represents the inter-electrode voltage; λ represents the wavelength; β represents the particle velocity; M0 represents the particle rest mass; c represents the speed of light; a represents the RFQ minimum aperture; I0 represents the zero-order Bessel function; L represents a cell length;

[0032] The acceleration efficiency range is determined as the second initial optimization parameter.

[0033] According to the design method of the RFQ accelerator for medical isotope production provided by the application, a third key factor causing the length of the RFQ accelerator to be longer is determined, and the structural parameters of the RFQ accelerator are optimized and designed based on the third key factor, to obtain a third initial optimization parameter, including:

[0034] Based on the preset values of the field flattening regulation, the beam transmission efficiency and the sparking coefficient, the beam dynamics simulation calculation of the RFQ accelerator is performed, to obtain the length range of the RFQ accelerator;

[0035] Based on the length range and the inter-electrode voltage range, the optimal length corresponding to the optimal inter-electrode voltage in the inter-electrode voltage range is determined;

[0036] The optimal length is determined as the third initial optimization parameter.

[0037] According to the design method of the RFQ accelerator for medical isotope production provided by the application, based on the optimized dynamic design scheme, the structural parameters of the RFQ accelerator are high-frequency designed, to determine a second optimization parameter, including:

[0038] The power loss of the RFQ accelerator with different preset structures is compared, and the preset structure with the optimal power is determined as the initial structure of the RFQ accelerator;

[0039] The field flattening tuning design is performed on the initial structure, to obtain a target structure of the RFQ accelerator;

[0040] The target structure is determined as the second optimization parameter.

[0041] According to the design method of the RFQ accelerator for medical isotope production provided by the application, based on the high-frequency design scheme, the structural parameters of the cooling flow channel in the RFQ accelerator are optimized, to obtain a third optimization parameter, including:

[0042] The high-frequency simulation calculation is performed on the RFQ accelerator, to determine the main part of the RFQ accelerator cavity heating;

[0043] Based on the main part, the structural parameters of the cooling flow channel in the RFQ accelerator cavity are designed under the premise of ensuring the mechanical strength and stability of the RFQ accelerator, and the structural parameters of the cooling flow channel are determined as the third optimization parameter.

[0044] The application further provides an ultra-high frequency normal-temperature linear accelerator system for medical isotope production, including:

[0045] Alpha ion source, used for generating alpha beam with high peak current, the energy of the alpha beam is 10-20keV, the current of the alpha beam is 10-15emA;

[0046] RFQ accelerator, connected with the alpha ion source through a low-energy transmission line, used for focusing, bunching and accelerating the alpha beam, the frequency of the RFQ accelerator is 700-850MHz, the energy of the alpha beam at the outlet of the RFQ accelerator is 6-8MeV;

[0047] Drift tube linear accelerator, connected with the RFQ accelerator, the frequency of the drift tube linear accelerator is 700-850MHz, the drift tube linear accelerator accelerates the high peak current alpha beam output by the RFQ accelerator.

[0048] The application provides an ultra-high frequency normal-temperature linear accelerator system for medical isotope production, the RFQ accelerator and the drift tube linear accelerator operate at a high duty cycle of 1%-2%, the average beam current is 100-200eμA, the RFQ accelerator adopts a quadrilateral four-wing structure, and the drift tube linear accelerator adopts a cross-shaped drift tube structure.

[0049] The design method of the RFQ accelerator for medical isotope production provided by the application selects the optimal working frequency range of the RFQ accelerator, optimizes the structural parameters of the RFQ accelerator at the optimal working frequency, shortens the length of the RFQ accelerator, reduces the production cost, and improves the transmission efficiency of the alpha beam. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0051] Figure 1 is one of the flowcharts of the design method of the RFQ accelerator for medical isotope production provided by the application.

[0052] Figure 2 is the second flowchart of the design method of the RFQ accelerator for medical isotope production provided by the application.

[0053] Figure 3 is a schematic diagram of the stable working frequency range and the minimum aperture range corresponding to the transverse stability region boundary.

[0054] Figure 4 Figure 3 is a flowchart of a design method of an RFQ accelerator for medical isotope production according to the present application.

[0055] Figure 5 Figure 4 is a flowchart of a design method of an RFQ accelerator for medical isotope production according to the present application.

[0056] Figure 6 Figure 5 is a flowchart of a design method of an RFQ accelerator for medical isotope production according to the present application.

[0057] Figure 7 Figure 6 is a curve of inter-electrode voltage versus cell number according to the present application.

[0058] Figure 8 Figure 7 is a schematic diagram of a transverse-longitudinal phase contrast before and after longitudinal acceptance optimization according to the present application.

[0059] Figure 9 Figure 6 is a flowchart of a design method of an RFQ accelerator for medical isotope production according to the present application.

[0060] Figure 10 Figure 7 is a flowchart of a design method of an RFQ accelerator for medical isotope production according to the present application.

[0061] Figure 11 Figure 8 is a schematic diagram of a structure of an ultra-high frequency room-temperature linear accelerator system for medical isotope production according to the present application.

[0062] Figure 12 Figure 9 is an RFQ accelerator with an octagonal four-wing structure according to the present application.

[0063] Figure 13 Figure 10 is an RFQ accelerator with a quadrilateral four-wing structure according to the present application.

[0064] Figure 14 Figure 11 is a schematic diagram of a comparison of high-frequency power loss between an octagonal four-wing structure and a quadrilateral four-wing structure of an RFQ accelerator according to the present application, wherein power oct represents the octagonal four-wing structure and power tet represents the quadrilateral four-wing structure.

[0065] Figure 15 Figure 12 is a schematic diagram of a cooling flow channel of a CH-DTL accelerator according to the present application.

[0066] Figure 16 Figure 13 is a schematic diagram of an electronic device according to the present application.

[0067] Reference signs:

[0068] 10, alpha ion source; 20, low energy transport line; 30, radio frequency quadrupole accelerator; 40, drift tube linac; 50, high energy transport system;

[0069] 41, accelerating cavity; 42, girder; 43, support rod; 44, drift tube; 45, cooling water path. DETAILED DESCRIPTION

[0070] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0071] The design method of the RFQ accelerator for medical isotope production will be described below. Figures 1-10 The design method of the RFQ accelerator for medical isotope production will be described below.

[0072] The embodiments of the present application provide a design method of an RFQ accelerator for medical isotope production, as shown in the figure, the design method comprises the following steps: Figure 1

[0073] Step 100, determining a target working frequency range of a radio frequency quadrupole (RFQ) accelerator.

[0074] Among them, the radio frequency quadrupole accelerator (RFQ accelerator) can adopt an ultra-high frequency RFQ accelerator, the optimal working frequency range of the ultra-high frequency RFQ accelerator is selected, and the optimal working frequency range is taken as the target working frequency range.

[0075] Step 200, based on the target working frequency range, optimizing the structure parameters of the RFQ accelerator to determine a first optimization parameter, the first optimization parameter is used to determine an optimized dynamic design scheme of the RFQ accelerator.

[0076] It can be understood that the RFQ accelerator will bring physical problems under the target working frequency range, the physical problems are researched, and a solution is proposed, the solution can be the design and optimization of the structure parameters of the RFQ accelerator, so as to determine the first optimization parameter, and the optimized dynamic design scheme of the RFQ accelerator can be obtained according to the first optimization parameter.

[0077] Step 300, based on the optimized dynamic design scheme, high frequency design is performed on the structure parameters of the RFQ accelerator to determine a second optimization parameter, the second optimization parameter is used to determine a high frequency design scheme of the RFQ accelerator.​

[0078] It can be understood that, based on the optimized dynamic design scheme, the structure parameters of the RFQ accelerator can be designed in high frequency for the purpose of low power loss and field flatness tuning, so as to determine the second optimization parameter, and the high frequency design scheme of the RFQ accelerator can be obtained according to the second optimization parameter.

[0079] Step 400, based on the high frequency design scheme, the structure parameters of the cooling flow channel in the RFQ accelerator are optimized to obtain the third optimization parameter, and the third optimization parameter is used to determine the physical design scheme of the RFQ accelerator.

[0080] It can be understood that, based on the high frequency design scheme, the cooling flow channel in the RFQ accelerator is optimized and designed to obtain the physical design scheme of the RFQ accelerator.

[0081] Step 500, based on the physical design scheme, the RFQ accelerator for medical isotope production is obtained.

[0082] It can be understood that, according to the physical design scheme, the process scheme of the RFQ accelerator is designed, so that the RFQ accelerator capable of meeting the medical isotope production can be obtained.

[0083] The design method of the RFQ accelerator for medical isotope production provided by the embodiment of the application can shorten the length of the RFQ accelerator, reduce the production cost, and improve the transmission efficiency of the alpha beam by selecting the optimal working frequency range of the RFQ accelerator and optimizing the structure parameters of the RFQ accelerator at the optimal working frequency.

[0084] Optionally, as shown in Figure 2 The step 100 can specifically include the following steps.

[0085] Step 110, based on the transverse stability condition of the RFQ accelerator, the stable working frequency range and the minimum aperture range corresponding to the transverse stability region boundary are determined.

[0086] It can be understood that, based on the transverse stability condition of the RFQ accelerator, the influence of the particle velocity at the end of the bunching section of the RFQ accelerator and the modulation factor on the transverse stability region boundary is explored to obtain the stable working frequency and the minimum aperture range corresponding to the transverse stability region boundary.

[0087] Step 120, the optimal working frequency range is determined from the stable working frequency range.

[0088] It can be understood that, based on the processing capacity, gain length, beam acceptance and power consumption, the optimal working frequency range and the minimum aperture range are determined from the stable working frequency range.

[0089] Step 130, determining the optimal working frequency range as the target working frequency range.

[0090] Optionally, in step 110, the obtained transverse stability region boundary corresponds to a stable working frequency range and a minimum aperture range, as shown in the following formula: Figure 3 wherein beta represents the velocity of the particle in the unit of light speed, and m represents the modulation factor, Figure 3 The five curves in the formula represent the stable region boundaries of beta and m at the end of different bunching sections. The points under the stable boundary curves are stable points, thereby determining the boundaries of power consumption (working frequency), machining precision, and stable region (minimum aperture). Preferably, the optimal working frequency range and the minimum aperture range used in the embodiment are 714-850 MHz and 0.8-0.95 cm, respectively.

[0091] Optionally, the target working frequency range of the embodiment is equivalent to an increase in working frequency compared with the existing RFQ accelerator. A series of physical problems caused by the increase in working frequency of the RFQ accelerator are studied, and the main problem is the weakening of the transverse focusing of the RFQ accelerator. A solution is proposed to design and optimize the parameters of the ultra-high frequency RFQ accelerator, and an optimized dynamic design scheme is obtained. As shown in the following formula: Figure 4 Step 200, based on the target working frequency range, optimizing the structural parameters of the RFQ accelerator to determine the first optimized parameters, including the following steps:

[0092] Step 210, based on the target working frequency range, determining the first key factor affecting the sparking coefficient of the RFQ accelerator, and based on the first key factor, optimizing the structural parameters of the RFQ accelerator to obtain the first initial optimized parameters.

[0093] It can be understood that, according to the target working frequency range, the key factors affecting the sparking coefficient of the ultra-high frequency RFQ accelerator are determined, and based on each key factor, the structural parameters of the ultra-high frequency RFQ accelerator are optimized to obtain the first initial optimized parameters.

[0094] Step 220, determining the second key factor causing insufficient transverse focusing of the RFQ accelerator, and based on the second key factor, optimizing the structural parameters of the RFQ accelerator to obtain the second initial optimized parameters.

[0095] It can be understood that the key factors causing insufficient transverse focusing of the ultra-high frequency RFQ accelerator are determined, and based on each key factor, the structural parameters of the ultra-high frequency RFQ accelerator are optimized to obtain the second initial optimized parameters.

[0096] Step 230: Determine the third key factor that causes the RFQ accelerator to be too long, and optimize the structural parameters of the RFQ accelerator based on the third key factor to obtain the third initial optimization parameters.

[0097] It is understandable that the key factors leading to the excessive length of the UHF RFQ accelerator are identified, and the structural parameters of the UHF RFQ accelerator are optimized based on these key factors. For example, a variable voltage scheme can be used to improve acceleration efficiency, controlling the length of the UHF RFQ accelerator within approximately 6 times the wavelength, thus obtaining the third initial optimized parameters. It should be noted that the desired length of the UHF RFQ accelerator is controlled within approximately 6 times the wavelength; in this embodiment, the length of the UHF RFQ accelerator is controlled within the range of approximately 5 to approximately 6 times the wavelength. Of course, in other embodiments, the specific length of the UHF RFQ accelerator is designed reasonably according to actual needs.

[0098] Step 240: Determine the fourth key factor that leads to low beam transmission efficiency, and optimize the structural parameters of the RFQ accelerator based on the fourth key factor to obtain the fourth initial optimization parameters.

[0099] For example, the beam is 4 He 2+ Beam current, determined to cause 4 He 2+ The key factors contributing to low beam transmission efficiency were identified, and the structural parameters of the UHF RFQ accelerator were optimized based on these key factors to obtain the fourth initial optimization parameters.

[0100] Step 250: Determine the fourth initial optimization parameter as the first optimization parameter.

[0101] It is understandable that the optimized dynamic design scheme of the RFQ accelerator is obtained based on the fourth initial optimization parameters. It should be noted that in other embodiments, some or all of the parameters related to the RFQ accelerator structural parameters from the first, second, third, and fourth initial optimization parameters can be used as the first optimization parameters to obtain the optimized dynamic design scheme.

[0102] Optional, such as Figure 5 As shown, step 210 may specifically include the following steps:

[0103] Step 211: Based on the Kilpatrick criterion, determine the range of the Kilpatrick field corresponding to the target operating frequency range.

[0104] It can be understood that W. D. Kilpatrick analyzed the data of radio frequency breakdown and defined the condition of non-breakdown operation, and proposed an equation for expressing the Kilpatrick result, which is often used in the design of radio frequency accelerator cavity at normal temperature, and is generally known as the design frequency of the cavity. Through the equation, the Kilpatrick electric field E K can be solved, and the equation is as follows:

[0105]

[0106] Therefore, the above equation is a transcendental equation about the electric field E K , and the value of E K corresponding to the frequency f is obtained by numerical solution by iteration method.

[0107] In this embodiment, the range of the Kilpatrick field corresponding to the target working frequency range is 24.9 MV / m-26.7 MV / m.

[0108] Step 212, based on the preset value of the RFQ accelerator sparking coefficient and the range of the Kilpatrick field, the maximum surface electric field range is determined.

[0109] It can be understood that by multiplying the range of the Kilpatrick field and the preset value of the sparking coefficient, the range of the maximum surface electric field can be obtained. For example, the sparking coefficient is 2.5, the range of the Kilpatrick field is 24.9 MV / m-26.7 MV / m, and the range of the maximum surface electric field is 62.25 MV / m-66.75 MV / m.

[0110] Step 213, based on the relationship between the maximum surface electric field of the RFQ accelerator and the inter-electrode voltage, the inter-electrode voltage range corresponding to the maximum surface electric field range is determined.

[0111] Specifically, based on the sparking coefficient of the RFQ accelerator, the relationship between the maximum surface electric field of the RFQ accelerator and the inter-electrode voltage is determined, and the relationship is Es=kV / (ma+a), wherein Es represents the maximum surface electric field, V represents the inter-electrode voltage, k represents the sparking coefficient, m represents the modulation factor, and a represents the minimum aperture.

[0112] Based on the above relationship between the maximum surface electric field and the inter-electrode voltage, the inter-electrode voltage range is determined. In the case where the maximum surface electric field range is 62.25 MV / m-66.75 MV / m, the inter-electrode voltage range is 54.59 kV-71.88 kV.

[0113] Step 214, the maximum surface electric field range and the inter-electrode voltage range are determined as the first initial optimization parameter.

[0114] It can be understood that the structural parameters of the RFQ accelerator are optimized based on the maximum surface electric field range and the inter-electrode voltage range.

[0115] Optionally, the step 220 can be implemented by the following way:

[0116] Based on the minimum aperture range, the inter-electrode voltage range and the requirement of the transverse focusing, the accelerating efficiency range is determined, the accelerating efficiency range is determined as the second initial optimization parameter, and the structural parameters of the RFQ accelerator are optimized based on the accelerating efficiency range.

[0117] Specifically, the accelerating efficiency range is determined based on the formula (1) and the formula (2).

[0118] B=eλ 2 XV / γM0c 2 a 2 (1)

[0119] X=1-AI0(ka)(2)

[0120] Wherein, A represents the accelerating efficiency, B represents the transverse focusing intensity, X represents the transverse focusing factor, a represents the minimum aperture, V represents the inter-electrode voltage; λ represents the wavelength; β represents the particle velocity; M0 represents the particle rest mass; c represents the speed of light; a represents the RFQ minimum aperture; I0 represents the zero-order Bessel function; L represents the cell length.

[0121] In this embodiment, in order to improve the transverse focusing, the accelerating efficiency range is obtained as 0.18-0.19 through calculation.

[0122] Optionally, as shown in the step 230, the step 230 can include the following steps: Figure 6

[0123] The step 231 includes: based on the preset values of the field flatness adjustment, the beam transmission efficiency and the sparking coefficient, performing beam dynamics simulation calculation on the RFQ accelerator to obtain a length range of the RFQ accelerator.

[0124] Wherein, the preset value of the sparking coefficient is determined according to the requirement of the sparking coefficient.

[0125] The step 232 includes: based on the length range and the inter-electrode voltage range, determining an optimal length corresponding to an optimal inter-electrode voltage in the inter-electrode voltage range.

[0126] It can be understood that based on the above determined inter-electrode voltage range, how the cavity of the RFQ accelerator reaches the optimal inter-electrode voltage is explored, and the length corresponding to the optimal inter-electrode voltage in the inter-electrode voltage range is determined as the optimal length.

[0127] ​Step 233, determining the optimal length as the third initial optimization parameter.

[0128] It can be understood that the structure parameters of the RFQ accelerator are optimized based on the optimal length.

[0129] Optionally, in step 231, based on the dynamic simulation calculation, when the length of the RFQ accelerator satisfies 5 times the wavelength to 6 times the wavelength, the field flatness adjustment is easier and the transmission efficiency is higher, therefore, the length of the RFQ accelerator ranges from 5 times the wavelength to 6 times the wavelength.

[0130] Optionally, step 232 can be implemented by the following way:

[0131] Based on the dynamic simulation design, the embodiment adopts the variable voltage scheme, specifically, the first three segments (radial matching segment, shaping segment, bunching segment) of the RFQ accelerator have weak transverse focusing, a constant inter-electrode voltage is maintained to provide strong transverse focusing, and only the inter-electrode voltage of the accelerating segment of the RFQ accelerator is changed to shorten the length of the RFQ; that is, the first three segments of the RFQ accelerator adopt constant voltage, and the accelerating segment of the RFQ accelerator adopts variable voltage.

[0132] Specifically, the determination of the constant voltage value: first, the range of the inter-electrode voltage satisfying the Kilpatrick criterion is calculated according to the theoretical formula; second, within this range, appropriate voltage values are selected by comprehensively considering factors such as transverse focusing strength and power consumption. In the embodiment, the selected voltage value of the constant voltage is 50.87kV.

[0133] The determination of the highest voltage value: first, the range of the inter-electrode voltage satisfying the Kilpatrick criterion is calculated according to the theoretical formula; second, within this range, appropriate voltage values are selected by comprehensively considering factors such as transverse focusing strength, power consumption, RFQ length, and beam transmission efficiency. In the embodiment, the selected voltage value of the highest voltage is 63.37kV.

[0134] Based on the constant voltage value and the highest voltage value, and after multiple simulation calculations, a voltage change curve is obtained, as shown in Figure 7 , to achieve the change from 50.87kV to 63.37kV. It can be seen that the variable voltage scheme can improve the acceleration efficiency, shorten the length of the RFQ accelerator, and control the length of the RFQ accelerator within about 6 times the wavelength, at which time the field flatness adjustment of the RFQ accelerator cavity is easier.

[0135] Further, step 240 can be implemented by the following way:

[0136] The key factors causing the low beam transmission efficiency of the alpha beam are determined, and the structural parameters of the RFQ accelerator are optimized based on the key factors, and the beam transmission efficiency of the accelerator is maximized to about 78.4% based on the optimization of the structural parameters and the variable voltage design.

[0137] It should be noted that the optimization of longitudinal acceptance by synchronous phase change weakens the longitudinal bunching in the bunching section, enhances the acceleration and transverse focusing capabilities, thereby optimizing the transverse and longitudinal focusing, bunching and acceleration capabilities, realizing the confinement of the high-current beam, and improving the RFQ beam transmission efficiency. According to multiple simulation calculations, as shown in Figure 8 , by optimizing the synchronous phase evolution process only, the number of lost particles is reduced, and the final beam transmission efficiency is improved to about 94.5% under the condition that the previous parameters remain unchanged.

[0138] Alternatively, as shown in Figure 9 , step 300, based on the optimized dynamic design scheme, the structural parameters of the RFQ accelerator are high-frequency designed to determine the second optimization parameter, and the design is specifically performed for the purpose of low power loss and field flat tuning, which can include the following steps:

[0139] Step 310, compare the power loss of RFQ accelerators with different preset structures to determine the preset structure with optimal power as the initial structure of the RFQ accelerator.

[0140] Among them, different preset structures refer to different physical structures of the RFQ accelerator, which can be different shapes of the cross section of the RFQ accelerator, such as octagonal or quadrangular structure, or different compositions of the RFQ accelerator, or other physical parameters such as the structural shape and connection relationship of the components of the RFQ accelerator.

[0141] It can be understood that by comparing and analyzing the power loss of different preset structures, the power loss is the minimum, that is, the power is optimal, and the preset structure with optimal power is determined as the initial structure from multiple different preset structures.

[0142] Step 320, field flat tuning design is performed on the initial structure to obtain the target structure of the RFQ accelerator.

[0143] It can be understood that the initial structure is subjected to field flat tuning design to determine the optimal structural change and realize field flat design under variable voltage field, so as to determine the optimal structure as the target structure of the RFQ accelerator.

[0144] Step 330, the target structure is determined as the second optimization parameter.

[0145] It can be understood that the high-frequency design scheme of the RFQ accelerator is determined based on the optimal structure.

[0146] In this embodiment, in step 310, the optimal power is 380-420kW. In step 320, the optimal quadrupole field irregularity of the RFQ accelerator is less than 2%.

[0147] Optionally, as shown in Figure 10 step 400, the structure parameters of the cooling flow channel in the RFQ accelerator are optimized based on the high-frequency design scheme to obtain third optimization parameters, which can specifically include the following steps:

[0148] In step 410, high-frequency simulation calculation is performed on the RFQ accelerator to determine the main parts of the RFQ accelerator cavity heating.

[0149] In step 420, the cooling flow channel structure parameters in the RFQ accelerator cavity are designed based on the main parts under the premise of ensuring the mechanical strength and stability of the RFQ accelerator, and the cooling flow channel structure parameters are determined as the third optimization parameters.

[0150] It can be understood that the cooling flow channel of the RFQ accelerator is optimized based on the high-frequency design scheme, deformation and stress analysis is performed, and a physical design scheme is obtained. Specifically, the main parts affecting the heating of the RFQ accelerator cavity are determined through high-frequency simulation design of the RFQ accelerator; based on the determined main parts of the RFQ accelerator cavity heating, the cooling flow channel in the RFQ accelerator cavity is designed under the premise of ensuring the mechanical strength and stability of the RFQ accelerator, which can work at a higher duty ratio and make the deformation and stress meet the requirements, so as to obtain the physical design scheme.

[0151] Preferably, after the cooling flow channel structure parameters in the RFQ accelerator cavity are designed, the RFQ working duty ratio can be 1%-2%, the temperature rise is less than 30℃, the deformation is less than 20μm, and the stress is less than 40Mpa.

[0152] The embodiment of the present application also provides an ultra-high frequency normal-temperature linear accelerator system for medical isotope production, as shown in Figure 11 The ultra-high frequency normal-temperature linear accelerator system includes an alpha ion source, a radio frequency quadrupole field accelerator (RFQ accelerator) and a drift tube linear accelerator (DTL).

[0153] The alpha ion source 10 is used to generate a high peak current alpha beam, the energy of the alpha beam is 10-20keV, and the intensity of the alpha beam is 10-15emA.

[0154] The RFQ accelerator is connected with the alpha ion source 10 through a low-energy transmission line 20, and is used for focusing, bunching and accelerating the alpha beam.

[0155] The drift tube linear accelerator 40 (DTL accelerator) is connected with the RFQ accelerator, and the frequency of the drift tube linear accelerator 40 is 700-850MHz.

[0156] Specifically, the RFQ accelerator is designed by using the design method of the RFQ accelerator for medical isotope production, so that the length of the RFQ accelerator is effectively shortened, the transmission efficiency of the alpha beam is improved, and the peak value of the outlet flow intensity is about 10emA.

[0157] The super-high-frequency normal-temperature linear accelerator system for medical isotope production provided by the embodiment of the present application can provide an alpha particle beam with an energy of 28-30MeV and an average flow intensity of 100-200eμA after the alpha beam generated by the alpha ion source 10 is accelerated by the RFQ accelerator and the DTL accelerator, and has the advantages of high peak and average beam intensity, high transmission efficiency and small transverse and longitudinal dimensions, so that the yield of isotopes can be improved and the production cost of the equipment can be reduced.

[0158] The super-high-frequency normal-temperature linear accelerator system for medical isotope production provided by the embodiment of the present application has a high acceleration gradient, the working frequency of the RFQ accelerator can be 714-850MHz, the length of the RFQ accelerator is short, and the length can be about 6-7m, which is reduced by half compared with the length of the existing low-frequency normal-temperature linear accelerator.

[0159] The super-high-frequency normal-temperature linear accelerator system for medical isotope production provided by the embodiment of the present application has a small transverse dimension, so that the processing cost is low.

[0160] It should be noted that the existing high-frequency normal-temperature linear accelerator is mainly used for accelerating proton beam, the maximum proton beam intensity is about 1 muA, the transmission efficiency is about 20-30%, and the transmission efficiency is low; and the super high-frequency normal-temperature linear accelerator system has the characteristics of high average flow intensity and high transmission efficiency, and can provide an alpha particle beam with a peak intensity of about 10 emA at a transmission efficiency of more than 90%, thereby effectively improving the production yield of medical isotope astatine-211 211 At).

[0161] Further, the super high-frequency normal-temperature linear accelerator system further comprises a high-energy transmission system connected to the drift tube linear accelerator, the drift tube linear accelerator is used to efficiently transmit the high peak value and average flow intensity alpha beam output by the drift tube linear accelerator to the target end, and reduce the target beam peak power, avoid thermal shock, and reduce the cooling pressure of the target cooling system, so that it can withstand 100-200 e muA alpha beam.

[0162] In an embodiment of the present application, the alpha ion source can adopt a superconducting electron cyclotron resonance (ECR) source or a hybrid ECR source, and the working frequency can be 18 GHz.

[0163] It can be understood that the normal-temperature ECR source can provide an alpha beam of 1 emA, and when the beam intensity is large, the beam quality is relatively poor, which is not conducive to the transmission of the subsequent acceleration structure and limits the beam intensity at the outlet. The present application adopts a superconducting ECR source or a hybrid ECR source, wherein the superconducting ECR source mainly refers to that the coil and the sextupole iron are in a superconducting state, and the hybrid ECR source mainly refers to that the coil is in a superconducting state and the sextupole iron is in a permanent magnet state.

[0164] Optionally, as shown in Figure 12 , the RFQ accelerator can adopt an octagonal four-wing structure; and as shown in Figure 13 , the RFQ accelerator can also adopt a quadrilateral four-wing structure. As shown in Figure 14 , the horizontal axis theta represents the chord angle of the pole head, and the vertical axis represents the power cavity power. Figure 14 Compared with the octagonal four-wing structure, the quadrilateral four-wing structure has a high-frequency power loss of 6-10%, can operate at a higher duty ratio, improves the average beam intensity, and the outlet beam average intensity is 100-200 euA. In addition, the quadrilateral structure is more conducive to field flat tuning of the voltage variation design, therefore, the RFQ accelerator preferably adopts a quadrilateral four-wing structure.

[0165] According to the embodiment of the present application, the DTL accelerator adopts a crossed-rod drift tube structure, that is, the DTL accelerator is a Crossed-Field Drift Tube Linear Accelerator (CH-DTL), and by virtue of the cooling channel design of the CH-DTL accelerator, the CH-DTL accelerator can work at a higher duty ratio, and the average beam intensity is improved, and the average beam intensity at the outlet of the CH-DTL accelerator is 100-200 eμA.

[0166] It can be understood that, at the same cavity pressure, the power of the CH-DTL accelerator is increased by about 17% compared with that of a Heavy Ion Drift Tube Linear accelerator (IH-DTL). Correspondingly, the peak electric field of the CH-DTL accelerator is reduced by 10% compared with that of the IH-DTL accelerator, and the IH-DTL accelerator has about 6%-10% of a dipole quantity due to the lateral asymmetry, and the CH-DTL accelerator of the embodiment does not have the problem of the dipole quantity. Therefore, from the structural point of view, the CH-DTL accelerator of the embodiment is more conducive to the design of the cooling channel around the drift tube, and is easier to realize the cooling of the drift tube, so that the CH-DTL accelerator can work at a higher duty ratio.

[0167] As shown in Figure 15 , a design scheme of a cooling channel of the CH-DTL accelerator of the embodiment is illustrated, wherein the CH-DTL accelerator comprises an accelerating cavity 41, the inner wall of the accelerating cavity 41 has two opposite large beams 42, the two large beams 42 have a support rod 43 therebetween, the middle part of the support rod 43 is formed with a drift tube 44, and the support rod 43 is formed with a cooling water channel 45. Even at a duty ratio of 10%, the maximum temperature rise on the accelerating cavity 41 is only 15 degrees, the maximum deformation is within 0.02 mm, and the maximum stress is less than 20 Mpa, which is more conducive to the design of the cooling channel around the drift tube.

[0168] Figure 16 An example of a schematic diagram of a physical structure of an electronic device is shown in Figure 16As shown, the electronic device can include a processor 1610, a communications interface 1620, a memory 1630, and a communications bus 1640, wherein the processor 1610, the communications interface 1620, and the memory 1630 complete mutual communication through the communications bus 1640. The processor 1610 can invoke a logic instruction in the memory 1630 to execute a design method of an RFQ accelerator for medical isotope production, the design method including: determining a target operating frequency range of a radio frequency quadrupole (RFQ) accelerator; based on the target operating frequency range, optimizing structure parameters of the RFQ accelerator to determine first optimization parameters, the first optimization parameters being used to determine an optimized dynamic design scheme of the RFQ accelerator; based on the optimized dynamic design scheme, performing high-frequency design on the structure parameters of the RFQ accelerator to determine second optimization parameters, the second optimization parameters being used to determine a high-frequency design scheme of the RFQ accelerator; based on the high-frequency design scheme, optimizing structure parameters of a cooling flow channel in the RFQ accelerator to obtain third optimization parameters, the third optimization parameters being used to determine a physical design scheme of the RFQ accelerator; and based on the physical design scheme, obtaining the RFQ accelerator for medical isotope production.

[0169] In addition, the logic instruction in the memory 1630 described above can be implemented in the form of a software functional unit and sold or used as an independent product, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or the part of the technical solutions that make essential contributions to the prior art or the part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the embodiments of the present application. The aforementioned storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0170] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program being stored in a non-transitory computer readable storage medium, and the computer program being capable of being executed by a processor to perform the design method of the RFQ accelerator for medical isotope production, the design method comprising: determining a target working frequency range of a Radio Frequency Quadrupole (RFQ) accelerator; optimizing structure parameters of the RFQ accelerator based on the target working frequency range to determine first optimization parameters, the first optimization parameters being used to determine an optimized dynamic design scheme of the RFQ accelerator; performing high frequency design on the structure parameters of the RFQ accelerator based on the optimized dynamic design scheme to determine second optimization parameters, the second optimization parameters being used to determine a high frequency design scheme of the RFQ accelerator; optimizing structure parameters of cooling channels in the RFQ accelerator based on the high frequency design scheme to obtain third optimization parameters, the third optimization parameters being used to determine a physical design scheme of the RFQ accelerator; and obtaining the RFQ accelerator for medical isotope production based on the physical design scheme.

[0171] In another aspect, the present application also provides a non-transitory computer readable storage medium, which stores a computer program, the computer program being capable of being executed by a processor to perform the design method of the RFQ accelerator for medical isotope production, the design method comprising: determining a target working frequency range of a Radio Frequency Quadrupole (RFQ) accelerator; optimizing structure parameters of the RFQ accelerator based on the target working frequency range to determine first optimization parameters, the first optimization parameters being used to determine an optimized dynamic design scheme of the RFQ accelerator; performing high frequency design on the structure parameters of the RFQ accelerator based on the optimized dynamic design scheme to determine second optimization parameters, the second optimization parameters being used to determine a high frequency design scheme of the RFQ accelerator; optimizing structure parameters of cooling channels in the RFQ accelerator based on the high frequency design scheme to obtain third optimization parameters, the third optimization parameters being used to determine a physical design scheme of the RFQ accelerator; and obtaining the RFQ accelerator for medical isotope production based on the physical design scheme.

[0172] The device embodiments described above are merely illustrative, and units described as separate components can or can not be physically separate, and components shown as units can or can not be physical units, i.e., can be located in one place or distributed on multiple network units. Part or all of the modules can be selected to achieve the purposes of the embodiments according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0173] Those skilled in the art can clearly understand the implementation of the various embodiments by means of software and necessary general hardware platforms through the description of the above embodiments, and of course, the implementation can also be through hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that makes a contribution, can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods of the various embodiments or some parts of the embodiments.

[0174] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for some technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A method of designing an RFQ accelerator for medical isotope production, characterized in that, The method comprises the following steps: determining a target working frequency range of the RFQ accelerator; optimizing structure parameters of the RFQ accelerator based on the target working frequency range to determine first optimization parameters, which are used to determine an optimized dynamic design scheme of the RFQ accelerator; performing high-frequency design on the structure parameters of the RFQ accelerator based on the optimized dynamic design scheme to determine second optimization parameters, which are used to determine a high-frequency design scheme of the RFQ accelerator; optimizing structure parameters of cooling flow channels in the RFQ accelerator based on the high-frequency design scheme to obtain third optimization parameters, which are used to determine a physical design scheme of the RFQ accelerator; obtaining the RFQ accelerator for medical isotope production based on the physical design scheme; wherein the step of optimizing the structure parameters of the RFQ accelerator based on the target working frequency range to determine the first optimization parameters comprises the following steps: determining a range of Kilpatrick fields corresponding to the target working frequency range based on the Kilpatrick criterion; determining a maximum surface electric field range based on a preset value of a sparking coefficient of the RFQ accelerator and the range of Kilpatrick fields; determining an inter-electrode voltage range corresponding to the maximum surface electric field range based on a relationship between the maximum surface electric field and the inter-electrode voltage of the RFQ accelerator; and determining the maximum surface electric field range and the inter-electrode voltage range as first initial optimization parameters; determining an acceleration efficiency range based on formulas (1) and (2); and determining the acceleration efficiency range as second initial optimization parameters; B = eλ 2 XV / γM0c 2 a 2 (1) X = 1 - AI0(ka) (2) wherein A represents an acceleration efficiency; B represents a transverse focusing strength; X represents a transverse focusing factor; a represents a minimum aperture; V represents an interelectrode voltage; and λ represents a wavelength; β represents a particle velocity; M0represents a particle rest mass; c represents a speed of light; a represents an RFQ minimum aperture; and I0represents a zeroth order Bessel function; L represents a cell length; performing beam dynamics simulation calculation on the RFQ accelerator based on preset values of field flattening adjustment, beam transmission efficiency and sparking coefficient to obtain a length range of the RFQ accelerator; determining an optimal length corresponding to an optimal inter-electrode voltage in the inter-electrode voltage range based on the length range and the inter-electrode voltage range; and determining the optimal length as third initial optimization parameters; determining a fourth key factor causing low beam transmission efficiency, and optimizing the structure parameters of the RFQ accelerator based on the fourth key factor to obtain fourth initial optimization parameters; determining the fourth initial optimization parameters as the first optimization parameters; wherein the step of performing high-frequency design on the structure parameters of the RFQ accelerator based on the optimized dynamic design scheme to determine the second optimization parameters comprises the following steps: comparing power losses of RFQ accelerators with different preset structures to determine a preset structure with optimal power as an initial structure of the RFQ accelerator; performing field flattening tuning design on the initial structure to obtain a target structure of the RFQ accelerator; determining the target structure as the second optimization parameters.

2. The design method of an RFQ accelerator for medical isotope production according to claim 1, characterized in that, The step of determining the target working frequency range of the RFQ accelerator comprises the following steps: determining a stable working frequency range and a minimum aperture range corresponding to a transverse stability region boundary based on a transverse stability condition of the RFQ accelerator; determining an optimal working frequency range from the stable working frequency range; The optimal working frequency range is determined as the target working frequency range.

3. The design method of an RFQ accelerator for medical isotope production according to claim 1 or 2, characterized in that, The structure parameters of the cooling flow channel in the RFQ accelerator are optimized based on the high-frequency design scheme, to obtain third optimization parameters, including: High-frequency simulation calculation is performed on the RFQ accelerator to determine the main parts of the RFQ accelerator cavity heating; Based on the main parts, the structure parameters of the cooling flow channel in the RFQ accelerator cavity are designed under the premise of ensuring the mechanical strength and stability of the RFQ accelerator, and the structure parameters of the cooling flow channel are determined as the third optimization parameters.

4. An ultra-high frequency normal-temperature linear accelerator system for medical isotope production, characterized by comprising: The design method of the RFQ accelerator for medical isotope production according to claim 1, the system comprises: An alpha ion source for generating a high peak current alpha beam, the energy of the alpha beam is 10-20keV, and the current of the alpha beam is 10-15emA; An RFQ accelerator connected with the alpha ion source through a low-energy transmission line, the RFQ accelerator is used for focusing, bunching and accelerating the alpha beam, the frequency of the RFQ accelerator is 700-850MHz, and the energy of the alpha beam at the outlet of the RFQ accelerator is 6-8MeV; A drift tube linear accelerator connected with the RFQ accelerator, the frequency of the drift tube linear accelerator is 700-850MHz, and the drift tube linear accelerator is used for accelerating the high peak current alpha beam output by the RFQ accelerator.

5. The ultra-high frequency normal-temperature linear accelerator system for medical isotope production according to claim 4, characterized by, The RFQ accelerator and the drift tube linear accelerator operate at a high duty cycle of 1%-2%, the average beam current is 100-200eμA, the RFQ accelerator adopts a quadrilateral four-wing structure, and the drift tube linear accelerator adopts a cross-shaped drift tube structure.

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