Medical cyclotron polymorphic tuning method and system

Abstract

The invention relates to the technical field of cyclotron current regulation, in particular to a medical cyclotron polymorphic tuning method and system, and the method comprises the steps: dividing change periods according to the similarity of the local change trend of high-frequency cavity pressure, and obtaining the change periods; according to the fluctuation amplitude of the cavity pressure rising section, the fluctuation frequency of the cavity pressure falling section and the frequency domain information difference between each change period and the adjacent period in each change period, the resonant frequency interference degree is obtained; obtaining a phase difference oscillation coefficient according to the stability degree of the phase difference change and the resonance frequency interference degree in each change period; obtaining a stable matching index according to the concentration condition of the value distribution of the phase difference oscillation coefficients of all the change periods; and calculating the excitation current variable quantity of the next change period according to the resonant frequency variable quantity of the current change period and the stable matching index. The excitation current can be adjusted in time to control the magnetic field intensity, and the tuning efficiency of the cyclotron is improved.

Description

Technical Field

[0001] This application relates to the technical field of cyclotron current regulation, and particularly to a multi-state tuning method and system for a medical cyclotron. Background Art

[0002] A medical cyclotron is a particle accelerator mainly used for producing positron radionuclides in nuclear medicine. The cyclotron accelerates charged particles and makes them strike the target material to generate the required radionuclides, which are widely used in PET / CT imaging, radiopharmaceutical therapy, and other nuclear medicine research. To enable the high-frequency cavity to operate normally at the designed frequency, precise machining and adjustment of the cavity are required to make it resonate at the selected center frequency.

[0003] When the cyclotron operates normally, the high-frequency cavity should be in a resonant state. The radio-frequency cavity body will have a small deformation due to the thermal instability of the cavity, resulting in a change in the resonant frequency and unable to effectively exert the performance of the accelerator. To ensure the stable operation and efficient acceleration of the accelerator, the frequency is usually adjusted to reduce the deformation caused by thermal instability of the high-frequency cavity. However, due to the thermal instability of the radio-frequency cavity body and the influence of the beam strength factor, it is difficult for the frequency of the high-frequency resonant cavity to be stably matched with the output frequency of the high-frequency power source, and it is impossible to adjust the excitation current in time to control the magnetic field strength, resulting in the defect of low tuning efficiency of the cyclotron. Summary of the Invention

[0004] To solve the above technical problems, the purpose of this application is to provide a multi-state tuning method and system for a medical cyclotron, and the specific technical solutions adopted are as follows: In the first aspect, an embodiment of this application provides a multi-state tuning method for a medical cyclotron, and the method includes the following steps: S1, obtain the high-frequency cavity pressure and the phase difference between the incident wave and the reflected wave of the high-frequency cavity during the operation of the medical cyclotron in real time; S2, divide the change period according to the similarity of the local change trend of the high-frequency cavity pressure at all times to obtain each change period; wherein, each change period includes a cavity pressure rising section and a cavity pressure falling section; according to the fluctuation amplitude of the cavity pressure rising section and the fluctuation frequency of the cavity pressure falling section within each change period, obtain the high-frequency cavity pressure fluctuation amount of each change period; S3, comprehensively obtain the resonance frequency interference degree of each change period based on the frequency domain information difference between each change period and its adjacent period and the high-frequency cavity pressure fluctuation amount; obtain the change stability degree of each change period according to the smoothness of the phase difference change within each change period; comprehensively obtain the phase difference oscillation coefficient of each change period based on the change stability degree and the resonance frequency interference degree of each change period; S4. Obtain a stable matching index based on the concentration of the numerical distribution of the phase difference oscillation coefficients of all change cycles; obtain the resonance frequency of the medical cyclotron operation in real time; calculate the excitation current change amount of the next change cycle according to the resonance frequency change amount and the stable matching index of the current change cycle.

[0005] Furthermore, the method for dividing each change cycle includes: Segment the time series of the high-frequency cavity pressure by using the cavity pressure change segment clustering algorithm to obtain each cavity pressure change segment; calculate the sum value of the slope values at all data points in each cavity pressure change segment; mark the cavity pressure change segment with the sum value greater than or equal to 0 as the cavity pressure rising segment; mark the cavity pressure change segment with the sum value less than 0 as the cavity pressure falling segment; Mark the time period composed of each cavity pressure rising segment and the subsequent cavity pressure falling segment as a change cycle.

[0006] Furthermore, the method for obtaining the high-frequency cavity pressure fluctuation amount of each change cycle includes: Perform curve fitting on all data points in the cavity pressure falling segment to obtain a fitting curve; detect all extreme points in the fitting curve; Denote the high-frequency cavity pressure fluctuation amount of the x-th change cycle as , ; In the formula, is the range of all data points in the cavity pressure rising segment of the x-th change cycle; N represents the total number of extreme points in the cavity pressure falling segment of the x-th change cycle, represents the absolute value of the difference between the i-th extreme point and the subsequent extreme point in the x-th change cycle, represents the time difference between the i-th extreme point and the subsequent extreme point in the x-th change cycle.

[0007] Furthermore, the method for obtaining the resonance frequency interference degree of each change cycle includes: For each change cycle, perform frequency domain feature extraction on the cavity pressure rising segment and the cavity pressure falling segment respectively to obtain the change coefficients of the cavity pressure rising segment and the cavity pressure falling segment; obtain the frequency component change values of each change cycle according to the differences in the change coefficients of the cavity pressure rising segment and the cavity pressure falling segment between each change cycle and its adjacent change cycle; Take the ratio of the high-frequency cavity pressure fluctuation amount and the frequency component change value of each change cycle as the resonance frequency interference degree of each change cycle.

[0008] Furthermore, the method for obtaining the frequency component change value of each change cycle includes: Calculate the Euclidean distance between the variation coefficients of each variation period and the previous and next variation periods in the rising section of the cavity pressure; take the mean value of the Euclidean distances of each variation period from the previous and next variation periods as the frequency component difference of each variation period in the rising section of the cavity pressure. Obtain the frequency component difference of each variation period in the falling section of the cavity pressure; take the mean value of the frequency component differences of each variation period in the rising and falling sections of the cavity pressure as the frequency component change value of each variation period.

[0009] Furthermore, obtaining the variation stability of each variation period according to the smoothness of the phase difference change within each variation period includes: Calculate the autocorrelation coefficient of the phase difference of each variation period, and take the sum value of the number 1 and the autocorrelation coefficient as the variation stability of each variation period.

[0010] Furthermore, obtaining the phase difference oscillation coefficient of each variation period by comprehensively considering the variation stability and resonance frequency interference degree of each variation period includes: taking the ratio of the resonance frequency interference degree to the variation stability of each variation period as the phase difference oscillation coefficient of each variation period.

[0011] Furthermore, the method for obtaining the stable matching index includes: Calculate the product of the mean value and the standard deviation of the phase difference oscillation coefficients of all variation periods; take the reciprocal of the product as the stable matching index.

[0012] Furthermore, calculating the excitation current change amount of the next variation period according to the resonance frequency change amount and the stable matching index of the current variation period specifically includes: denoting the excitation current change amount of the next variation period as I, ; where is the stable matching index; C is the difference in the resonance frequency values between the end moment and the initial moment of the current period; is the exponential function with the natural constant as the base; T is the preset magnitude conversion coefficient.

[0013] In a second aspect, an embodiment of the present application further provides a multi-state tuning system for a medical cyclotron, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of the above-mentioned medical cyclotron multi-state tuning method are implemented.

[0014] The present application has at least the following beneficial effects: This application analyzes the problem that during the tuning process, due to the thermal instability of the radio frequency cavity body and the influence of factors such as the strength of the beam current, it is difficult for the frequency of the high-frequency resonant cavity to be in a stable matching state with the output frequency of the high-frequency power source. First, it analyzes the influence of the unstable factors of the radio frequency cavity body on the stability of the resonant frequency, calculates the fluctuation amount of the cavity pressure through the change characteristics of the high-frequency cavity pressure, and reflects the degree of influence on the resonant frequency. Further, it analyzes the frequency domain information difference caused by the interference intensity and the instantaneous change degree of the phase difference between the incident wave and the reflected wave, combines the fluctuation amount of the cavity pressure to calculate the phase difference oscillation coefficient, and reflects the degree of mismatch between the output frequency of the power source and the resonant frequency of the high-frequency cavity inside the cyclotron. Finally, based on the change characteristics of the phase difference oscillation coefficient, it calculates the stable matching index, comprehensively evaluates the matching state characteristics between the output frequency of the power source and the resonant frequency of the high-frequency cavity within multiple consecutive change cycles, and evaluates the operating state of the current cyclotron. According to the evaluation results, it adjusts the change amount of the excitation current. This application can timely adjust the excitation current, improve the adjustment accuracy, and thus improve the tuning efficiency of the cyclotron. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a flowchart of the steps of a multi-state tuning method for a medical cyclotron provided by an embodiment of the present application; Figure 2 It is a block diagram for obtaining the interference degree of the resonant frequency provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Without conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0019] The following specifically describes the specific solutions of a multi-state tuning method and system for a medical cyclotron provided by the present application in conjunction with the accompanying drawings.

[0020] Please refer to Figure 1 , which shows a flowchart of the steps of a multi-state tuning method for a medical cyclotron provided by an embodiment of the present application. The method includes the following steps: S1. Real-time obtain the high-frequency cavity pressure during the operation of the medical cyclotron and the phase difference between the incident wave and the reflected wave of the high-frequency cavity.

[0021] A specific implementation scenario of the present application is the frequency coordination scenario of the cyclotron; the high-frequency structure in the medical cyclotron uses an asymmetric half-wavelength cavity. In view of the problem that the resonant frequency of the high-frequency cavity in the cyclotron gradually changes, the high-frequency system usually adopts a scheme in which the output frequency of the power source is matched with the resonant frequency of the high-frequency cavity in real time. The magnet system in the medical cyclotron provides a magnetic field for the charged particles to perform circular motion and realizes the focusing of the particles. In the cyclotron, the excitation current is adjusted according to the actual operating frequency of the high-frequency cavity to change the magnetic field strength of the cyclotron, so that the cyclotron frequencies of the accelerated ions at different radii are equal.

[0022] During the normal operation of the cyclotron, the resonant frequency of the cavity and the output frequency of the high-frequency power source are always in a matching state. However, due to the differences in thermal losses and the influence of factors such as the strength change of the beam current, the resonant frequency of the cavity is not matched with the output frequency of the power source, thus affecting the performance of the cyclotron. Since the phase difference between the incident wave signal and the reflected wave signal in the high-frequency cavity is a function of the difference between the output frequency of the power source and the resonant frequency of the high-frequency cavity. Therefore, in this embodiment, the matching relationship between the output frequency of the power source and the resonant frequency of the high-frequency cavity is detected by detecting the phase difference to reflect whether it remains stable.

[0023] To sum up, in order to evaluate the influence of the change of the resonant frequency and the matching state between the resonant frequency and the output frequency of the power source. In this embodiment, the corresponding high-frequency cavity pressure data and the phase difference data between the incident wave signal and the reflected wave signal of the high-frequency cavity are obtained through the AFC (Automatic Frequency Control) in the cyclotron. And the above-mentioned various data are sampled at equal intervals, the sampling interval is set to 1 second, and the time period length of the obtained various data is 10 minutes.

[0024] S2. Divide the change period according to the similarity of the local change trend of the high-frequency cavity pressure at all times to obtain each change period; where each change period includes a cavity pressure rising section and a cavity pressure falling section; according to the fluctuation amplitude of the cavity pressure rising section and the fluctuation frequency of the cavity pressure falling section within each change period, obtain the high-frequency cavity pressure fluctuation amount of each change period.

[0025] Resonance offset may occur inside the cyclotron due to thermal instability of the radio frequency cavity body and varying factors such as the strength of the beam current. The high-frequency cavity voltage is the excitation voltage applied to achieve stable frequency tracking, and the degree of its change reflects the degree of interference of the resonance frequency by the above factors. Therefore, in this embodiment, the variation characteristics of the high-frequency cavity voltage are first analyzed. The high-frequency cavity voltage data has certain periodic fluctuation characteristics. The data within each variation period shows a process of rapid short-term rise followed by irregular decline, and there are differences in the fluctuation characteristics of the high-frequency cavity voltage data in different variation periods.

[0026] To analyze the periodic fluctuation characteristics of the high-frequency cavity voltage data, first, a clustering algorithm for variable-length cavity voltage change segments is used to segment the time series of the high-frequency cavity voltage to obtain each cavity voltage change segment. Among them, the minimum length and the maximum length of the cavity voltage change segment are set to 60 and 120 respectively, and the mode category of clustering is set to 2. The slope values at all data points in each cavity voltage change segment are calculated respectively, and the rise and fall trends of the cavity voltage change segment are judged according to the positive and negative of the sum of the slope values corresponding to all data points. The cavity voltage change segments are recorded as two modes, namely the cavity voltage rising segment and the cavity voltage falling segment, specifically, the cavity voltage change segment with the sum value greater than or equal to 0 is recorded as the cavity voltage rising segment; the cavity voltage change segment with the sum value less than 0 is recorded as the cavity voltage falling segment. These two modes of cavity voltage change segments appear alternately, and the time period covered by each cavity voltage rising segment and the immediately following cavity voltage falling segment is recorded as a variation period.

[0027] After the above-mentioned variation period division is completed, when the resonance frequency is interfered by different degrees, the variation amplitude of the cavity voltage rising segment within the variation period is different, and the interference will cause non-linear release of energy, resulting in more complex variation characteristics when the cavity voltage drops, with a higher fluctuation frequency, making the degree of tortuosity of the curve corresponding to the cavity voltage falling segment different. Specifically, if the degree of interference is greater, the variation amplitude of the cavity voltage rising segment will be larger, and the cavity voltage falling segment will show fluctuations of multiple amplitude decreases and increases during the falling process. To analyze this characteristic of the cavity voltage falling segment, this application first uses polynomial fitting technology for fitting to obtain the fitting curve of the cavity voltage falling segment, and then calculates all the extreme points in the fitting curve. The degree of tortuosity of the curve corresponding to the cavity voltage falling segment can be reflected by the amplitude difference and the time difference between the extreme points. Thus, taking the high-frequency cavity voltage data of the x-th variation period as an example, the calculation formula for the high-frequency cavity voltage fluctuation amount within the variation period is: In the formula, represents the high-frequency cavity voltage fluctuation amount of the x-th variation period, is the range of all data points in the cavity voltage rising segment within the x-th variation period; N represents the total number of extreme points in the cavity voltage falling segment within the x-th variation period. denotes the absolute value of the difference between the \(i\)-th extreme point and the next extreme point within the \(x\)-th change period, denotes the time difference between the \(i\)-th extreme point and the next extreme point within the \(x\)-th change period.

[0028] When the range of the cavity pressure rising section is relatively large, it indicates that the change amplitude of the high-frequency cavity pressure data during the rising process within the change period is greater; the larger the ratio of the value of the extreme point to the time, the greater the degree of tortuosity of the corresponding curve in the cavity pressure falling section within the change period, and the greater the resulting high-frequency cavity pressure fluctuation amount, indicating that the high-frequency cavity pressure fluctuation within the change period is more obvious and frequent.

[0029] S3. By synthesizing the frequency domain information differences and high-frequency cavity pressure fluctuation amounts between each change period and its adjacent period, the resonance frequency interference degree of each change period is obtained; according to the stability degree of the phase difference change within each change period, the change stability degree of each change period is obtained; by synthesizing the change stability degree and resonance frequency interference degree of each change period, the phase difference oscillation coefficient of each change period is obtained.

[0030] In a high-frequency cavity, if the occurrence of resonance frequency interference is more frequent, the frequency domain information of the cavity pressure change segments with the same trend within each change period and its adjacent change period is usually closer. For example, when the fluctuation amounts of the cavity pressure rising section and the cavity pressure falling section in adjacent change periods are both large, the differences between various frequency components in the frequency domain where the cavity pressure change segments with the same trend are located are smaller.

[0031] Therefore, the present application first uses the discrete cosine transform technology to extract the frequency domain characteristics of the high-frequency cavity pressure within each change period. The input of the DCT is the cavity pressure rising section and the cavity pressure falling section within the change period, and the output is a set of transformation coefficients corresponding to the cavity pressure rising section and the cavity pressure falling section within the change period respectively. The transformation coefficients are a set of complex numbers, reflecting the amplitude and phase of the energy distribution of the input data at different frequencies.

[0032] Then, the Euclidean distances between the change coefficients of the cavity pressure rising section in the \(x\)-th change period and the cavity pressure rising sections in the two adjacent change periods before and after are calculated respectively, and the mean value of the Euclidean distances is used as the frequency component difference of the cavity pressure rising section. When the frequency component difference value of the cavity pressure rising section or the frequency component difference value of the cavity pressure falling section is relatively small, it indicates that the resonance frequency is more likely to be continuously interfered. Therefore, the same calculation method as the frequency component difference of the cavity pressure rising section can be used to obtain the frequency component difference of the cavity pressure falling section; the mean value of the frequency component differences of the cavity pressure rising section and the cavity pressure falling section in the \(x\)-th change period is used as the frequency component change value of the \(x\)-th change period . The obtained The smaller it is, the more likely the resonance frequency corresponding to the change period is to be continuously interfered. It should be noted that if only the previous or the next adjacent change period exists in the first and last change periods during the calculation process, only the data within a single adjacent change period is calculated.

[0033] Furthermore, if the high-frequency cavity pressure fluctuation within a certain change period is more obvious and the possibility of simultaneous interference in adjacent change periods is higher, it can indicate that the degree of interference on the resonance frequency of the cyclotron within this change period is greater. Therefore, the resonance frequency interference degree is calculated by comprehensively considering the high-frequency cavity pressure fluctuation amount and the frequency component change value as follows: In the formula, represents the high-frequency cavity pressure fluctuation amount of the x-th change period, represents the frequency component change value of the x-th change period, represents the resonance frequency interference degree within the x-th change period. The larger the high-frequency cavity pressure fluctuation amount, the more obvious the high-frequency cavity pressure fluctuation within the change period, and the smaller the frequency component change value, and the higher the possibility of simultaneous interference in adjacent change periods, the larger the obtained , indicating that the degree of interference on the resonance frequency within this change period is greater.

[0034] While the resonance frequency is interfered, in order to ensure the resonance acceleration of particles, the magnetic field inside the cyclotron needs to be adjusted according to the actually operating resonance frequency. The change of the magnetic field will inevitably cause a change in the phase. The phase difference data reflects to a certain extent the matching state between the output frequency of the power source and the resonance frequency of the high-frequency cavity. The severity of the instantaneous change of the phase difference data indicates the matching degree between the output frequency of the power source and the resonance frequency of the high-frequency cavity at this time.

[0035] In the above calculation process, different change periods are divided. To analyze the influence of the interference degree of the resonance frequency on the phase difference data under the same change period, the phase difference data is analyzed based on the above change period. Specifically, there are large differences in the phase difference data on both sides at multiple point positions of the phase difference data, that is, the trends and numerical sizes of the phase difference data on both sides of different data points deviate greatly. Based on this feature, in this embodiment, taking the phase difference data of the x-th change period as an example, the autocorrelation coefficient of the phase difference of the x-th change period is calculated, and the sum value of the number 1 and the autocorrelation coefficient is used as the change stability of the x-th change period , indicating the smoothness of the phase difference change of the change period.

[0036] Further, when the resonance frequency interference degree represents the matching state between the output frequency of the power source and the resonance frequency of the high-frequency cavity, and has a co-directional change relationship with the change of the phase difference, therefore, by combining the resonance frequency interference degree and the stability of the phase difference change, the phase difference oscillation coefficient is calculated. The calculation formula is as follows: In the formula, represents the phase difference oscillation coefficient of the x-th change period, represents the resonance frequency interference degree within the x-th change period; represents the change stability of the x-th change period. When the resonance frequency interference degree is larger, it is more likely to affect the matching state between the output frequency of the power source and the resonance frequency of the high-frequency cavity. At this time, the unstable change of the phase difference is larger, and the obtained phase difference oscillation coefficient is larger, indicating that the oscillation of the phase difference data within this change period is more obvious, and the output frequency of the power source and the resonance frequency of the high-frequency cavity in the cyclotron may be less matched.

[0037] In this embodiment, the block diagram for obtaining the resonance frequency interference degree is as shown in Figure 2 shown.

[0038] S4. According to the concentration of the numerical distribution of the phase difference oscillation coefficients of all change periods, obtain the stable matching index; obtain the resonance frequency of the medical cyclotron operation in real time; calculate the change amount of the excitation current in the next change period according to the resonance frequency change amount and the stable matching index of the current change period.

[0039] During the operation of the cyclotron, in a good operating state, particles continuously and stably perform resonance acceleration, and the change degree of the phase difference data in consecutive change periods is similar and relatively stable. If abnormal vibration is caused by interference, there are large fluctuations in the change degree of the phase difference data in consecutive change periods. Further, by combining the matching state characteristics between the output frequency of the power source and the resonance frequency of the high-frequency cavity in multiple consecutive change periods, the operating state of the current cyclotron is evaluated.

[0040] Calculate the product of the mean and standard deviation of the phase difference oscillation coefficients of all change periods; take the reciprocal of the product as the stable matching index, and the stable matching index represents the stable matching degree between the output frequency of the power source and the resonance frequency of the high-frequency cavity. The larger the stable matching index, the more stable the resonance acceleration of the cyclotron for particles in the acquisition time period.

[0041] When the resonance frequency deviates, the output frequency of the power source and the resonance frequency will be in a mismatched state. To meet the requirements of isochronous acceleration, the magnetic field strength needs to be adjusted according to the actual operating frequency, that is, the excitation current needs to be changed accordingly.

[0042] In this application, by analyzing the variation characteristics of the high-frequency cavity pressure data and the phase difference data within the current time period, the stable matching index between the output frequency of the power source and the resonance frequency of the high-frequency cavity is calculated. This value reflects the stability of the cyclotron for particle resonance acceleration in the current state. Based on the stable matching index, the excitation current is adjusted. When the stable matching index is larger, it indicates that the performance of the current cyclotron is better, and the adjustment intensity of the excitation current is smaller; while when the stable matching index is smaller, it indicates that the performance of the current cyclotron is worse, and the adjustment intensity of the excitation current should be increased.

[0043] Specifically, the resonance frequency values at the last moment and the initial moment within the current change period are obtained through the AFC control system. The calculation formula for the change amount of the excitation current in the next change period is: . Where I is the change amount of the excitation current in the next change period; is the stable matching index; C is the difference in resonance frequency values between the end moment and the initial moment of the current period; is the exponential function with the natural constant e as the base, and the unit of the data is not involved in the calculation; where T is the preset magnitude conversion coefficient, which is used to convert the calculation result to the current magnitude and further adjust the current value. In this embodiment, T = 150.

[0044] During the tuning process, if C is positive, the excitation current needs to be increased at this time. On the contrary, if C is negative, the excitation current is decreased. I is the change amount of the increase or decrease of the excitation current. By adjusting the excitation current, the magnetic field strength of the cyclotron is changed, and then the medical cyclotron is tuned.

[0045] Based on the same inventive concept as the above method, the embodiment of this application also provides a multi-state tuning system for a medical cyclotron, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-mentioned multi-state tuning methods for a medical cyclotron.

[0046] Through the above description of the embodiments in conjunction with the drawings, those skilled in the art can understand that for the convenience and simplicity of description, only the above-mentioned division of each functional module is used as an example. In actual applications, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the system is divided into different functional modules to complete all or part of the functions described above.

[0047] The above content is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application, and all of them should be covered by the protection scope of this application.

Claims

1. A medical cyclotron multi-state tuning method, characterized in that: The method comprises the following steps: S1, real-time acquisition of the high-frequency cavity pressure and the phase difference between the incident wave and the reflected wave of the high-frequency cavity during the operation of the medical cyclotron; S2, dividing the change period according to the similarity of the local change trend of the high-frequency cavity pressure at all times to obtain each change period; wherein each change period includes a cavity pressure rise segment and a cavity pressure drop segment; according to the fluctuation amplitude of the cavity pressure rise segment and the fluctuation frequency of the cavity pressure drop segment in each change period, the high-frequency cavity pressure fluctuation amount of each change period is obtained; S3, comprehensively analyzing the frequency domain information difference between each change period and its adjacent period and the high-frequency cavity pressure fluctuation momentum, obtain the resonant frequency interference degree of each change period; according to the smoothness of the phase difference change in each change period, obtain the change stability of each change period; comprehensively analyzing the change stability of each change period and the resonant frequency interference degree, obtain the phase difference oscillation coefficient of each change period; S4, according to the concentration of the numerical distribution of the phase difference oscillation coefficient of all change cycles, a stable matching index is obtained; the resonant frequency of the medical cyclotron is obtained in real time; and the excitation current change amount of the next change cycle is calculated according to the resonant frequency change amount of the current change cycle and the stable matching index.

2. A medical cyclotron multi-state tuning method as claimed in claim 1, characterized in that: The method for dividing each change period includes: The time series of high-frequency cavity pressure is segmented by using the cavity pressure change segment clustering algorithm to obtain each cavity pressure change segment; the sum of the slope values ​​at all data points in each cavity pressure change segment is calculated; the cavity pressure change segment whose sum is greater than or equal to 0 is recorded as a cavity pressure rising segment; the cavity pressure change segment whose sum is less than 0 is recorded as a cavity pressure falling segment; The time period consisting of each cavity pressure rising segment and the subsequent cavity pressure falling segment is recorded as a variation cycle.

3. A medical cyclotron multi-state tuning method as claimed in claim 1, characterized in that: The method for obtaining the high-frequency cavity pressure fluctuation quantity of each change period includes: Perform curve fitting on all data points in the cavity pressure drop section to obtain a fitting curve; detect all extreme value points in the fitting curve; The high-frequency cavity pressure fluctuation momentum of the x-th variation period is recorded as , ; In the formula, is the range of all data points in the rising segment of the cavity pressure in the x-th change cycle; N represents the total number of extreme value points in the falling segment of the cavity pressure in the x-th change cycle, It represents the absolute value of the difference between the ith extreme point and the next extreme point in the xth change cycle. It represents the time difference between the ith extreme point and the next extreme point in the xth change cycle.

4. A medical cyclotron multi-state tuning method as claimed in claim 1, characterized in that: The method for obtaining the resonant frequency interference degree of each change period includes: For each change cycle, frequency domain features are extracted for the cavity pressure rising section and the cavity pressure falling section respectively to obtain the change coefficients of the cavity pressure rising section and the cavity pressure falling section; according to the difference in the change coefficients of each change cycle and its adjacent change cycle in the cavity pressure rising section and the cavity pressure falling section respectively, the frequency component change value of each change cycle is obtained; The ratio of the high-frequency cavity pressure fluctuation amplitude to the frequency component change value in each change period is taken as the resonant frequency interference degree in each change period.

5. A medical cyclotron multi-state tuning method as claimed in claim 4, characterized in that: The method for obtaining the frequency component change value of each change period includes: Calculate the Euclidean distance between the coefficient of change of each change cycle and the previous and next change cycles in the cavity pressure rising section; take the average of the Euclidean distances between each change cycle and the previous and next change cycles as the frequency component difference of each change cycle in the cavity pressure rising section; The frequency component difference of each change cycle in the cavity pressure drop section is obtained; the average value of the frequency component difference of each change cycle in the cavity pressure increase section and the cavity pressure drop section is used as the frequency component change value of each change cycle.

6. A medical cyclotron multi-state tuning method as claimed in claim 1, characterized in that: The change stability of each change period is obtained according to the smoothness of the phase difference change in each change period, including: The autocorrelation coefficient of the phase difference of each change period is calculated, and the sum of the value 1 and the autocorrelation coefficient is used as the change stability of each change period.

7. A medical cyclotron multi-state tuning method as claimed in claim 1, characterized in that: The phase difference oscillation coefficient of each change period is obtained by integrating the change stability and the resonant frequency interference of each change period, including: taking the ratio of the resonant frequency interference of each change period to the change stability as the phase difference oscillation coefficient of each change period.

8. The multi-state tuning method for a medical cyclotron according to claim 1, characterized in that: The method for obtaining the stable matching index includes: The product of the mean and standard deviation of the phase difference oscillation coefficients of all change cycles is calculated; and the reciprocal of the product is used as the stable matching index.

9. The medical cyclotron multi-state tuning method according to claim 1, characterized in that: The calculation of the excitation current variation in the next variation cycle according to the resonant frequency variation in the current variation cycle and the stable matching index specifically includes: recording the excitation current variation in the next variation cycle as I, ;in, is the stable matching index; C is the difference between the resonant frequency values ​​at the end and the beginning of the current cycle; is an exponential function with a natural constant as the base; T is a preset magnitude conversion coefficient.

10. A medical cyclotron multi-state tuning system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the medical cyclotron multi-state tuning method as described in any one of claims 1-9 are implemented.

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