Medical cyclotron beam centering adjustment method and system

Abstract

The application relates to the technical field of plasma, in particular to a medical cyclotron beam centering adjustment method and system. The method comprises the following steps: acquiring a magnetic field sequence, a beam sequence and a current sequence; obtaining a beam fluctuation factor according to the difference in lag number corresponding to the maximum autocorrelation coefficient of the magnetic field sequence and the beam sequence, the correlation of the magnetic field sequence and the beam sequence, and the difference in the maximum autocorrelation coefficient; forming a beam fluctuation sequence by using the beam fluctuation factor; dividing the beam fluctuation sequence, and also dividing the current sequence; fitting a straight line based on the current fluctuation sequence and the current sequence; obtaining the current influence intensity at the current moment according to the difference between the excitation current in all sub-sequences and the overall excitation current of the current sequence and the mean square error; improving the proportional term according to the current influence intensity, controlling the excitation current based on the proportional term, and adjusting the proportional term in real time to optimize the magnetic field control effect. The application realizes higher and more stable nuclide production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plasma, in particular to a medical cyclotron beam centering adjustment method and system. BACKGROUND

[0002] With the increasing demand for radionuclides, higher requirements are put forward for the adjustment and control of accelerator beams to meet the needs of different radionuclide production. Beam centering adjustment can ensure that the beam generated by the accelerator accurately hits the target material, thereby efficiently producing the required radionuclides. In addition, accurate beam centering can also improve the operating efficiency of the accelerator, reduce operating costs, and help improve the safety and accuracy of nuclear medicine diagnosis and treatment.

[0003] During the operation of the cyclotron, insufficient magnetic field modulation usually occurs in the transition region of the cyclotron, i.e., the process of gradually increasing particle energy. The main reason for this problem is that the axial magnetic focusing ability is weak, and the particle energy is low at this stage, resulting in poor particle motion stability and thus easy beam loss. This loss not only affects the production efficiency of radionuclides, but also reduces the overall performance of the accelerator. Insufficient magnetic field modulation increases the instability of the beam, which in turn increases the beam loss, which directly affects the yield and quality of radionuclides. For medical cyclotrons, this reduces the production of radionuclides and affects their application effect in PET / CT and other medical imaging technologies. SUMMARY

[0004] To solve the technical problem of poor magnetic field regulation effect, the present application provides a medical cyclotron beam centering adjustment method and system, and the technical solution adopted is as follows:

[0005] In a first aspect, the present application provides a medical cyclotron beam centering adjustment method, which comprises the following steps:

[0006] Based on different sensors, the magnetic field sequence, the beam sequence and the current sequence at the current time are collected;

[0007] The autocorrelation coefficients of the sequence at different lags are calculated for the magnetic field sequence and the beam sequence respectively, and the most relevant lag difference is obtained based on the autocorrelation coefficients. The magnetic field beam stability is obtained based on the maximum autocorrelation coefficient difference of the magnetic field sequence and the beam sequence. The beam fluctuation factor at the current time is obtained according to the most relevant lag difference, the magnetic field beam stability and the correlation between the magnetic field sequence and the beam sequence;

[0008] The beam current oscillation sequence is formed by a preset number of beam current oscillation factors before the current time; all beam current oscillation factors in the beam current oscillation sequence are clustered into a plurality of subsequences and labeled, and the current sequence is divided into a plurality of subsequences according to the division result of the beam current oscillation sequence; the same labeled subsequence corresponding to the beam current oscillation sequence and the current sequence is linearly fitted to obtain the corresponding mean square error; the current influence intensity at the current time is obtained according to the difference between the excitation current in all sub-sequences of the current sequence and the overall excitation current of the current sequence and the mean square error.

[0009] The proportional term of the PID control algorithm is improved according to the current influence intensity, and the excitation current is controlled according to the improved proportional term, integral term and differential term, and the proportional term is adjusted in real time to optimize the magnetic field control effect.

[0010] In the above scheme, the present application proposes a medical cyclotron beam centering adjustment method and system. For the evaluation of the stability of the magnetic field and the beam in the medical cyclotron, the autocorrelation analysis algorithm and the Pearson correlation analysis algorithm are used to reflect the comprehensive characteristics of the stability of the magnetic field and the beam, solving the problem of difficult quantitative evaluation of beam stability. For the influence of excitation current change on beam stability, the DBSCAN density clustering algorithm and the least squares linear fitting are used to reflect the average influence of excitation current change on beam stability, excluding the influence of single data point fluctuation. By improving the PID control algorithm, the proportional term is dynamically adjusted to realize real-time feedback and adjustment of excitation current change, optimize magnetic field change, and realize more efficient and stable nuclide production efficiency.

[0011] In one embodiment, the magnetic field intensity, beam intensity and excitation current at a preset number of time points before the current time are collected, and the magnetic field intensity, beam intensity and excitation current are sorted respectively to obtain the magnetic field sequence, beam sequence and current sequence at each collection time.

[0012] In one embodiment, the method for calculating the autocorrelation coefficient of the sequence under different lags for the magnetic field sequence and the beam sequence respectively, and obtaining the most relevant lag difference based on the lag difference under the autocorrelation coefficient is:

[0013] A plurality of lags are preset, and the maximum value of the lag is half of the sequence;

[0014] When the autocorrelation coefficient of the magnetic field sequence is maximum, the corresponding lag is recorded as the first lag;

[0015] When the autocorrelation coefficient of the beam sequence is maximum, the corresponding lag is recorded as the second lag;

[0016] The absolute value of the difference between the first lag and the second lag is taken as the most relevant lag difference.

[0017] In one embodiment, the method for obtaining the magnetic field-beam current stability based on the maximum autocorrelation coefficient difference of the magnetic field sequence and the beam current sequence is as follows:

[0018] The maximum value of the autocorrelation coefficient of the magnetic field sequence at all lags and the average of the maximum values of the autocorrelation coefficients of the beam current sequence at all lags are taken as the magnetic field-beam current stability.

[0019] In one embodiment, the method for obtaining the beam current fluctuation factor according to the most relevant lag difference, the magnetic field-beam current stability, and the correlation of the magnetic field sequence and the beam current sequence is as follows:

[0020] The beam current fluctuation factor is negatively correlated with the magnetic field-beam current stability and the correlation of the magnetic field sequence and the beam current sequence, and is positively correlated with the most relevant lag difference.

[0021] In one embodiment, the method for clustering all beam current fluctuation factors in the beam current fluctuation sequence, dividing them into a plurality of subsequences, and labeling them, and dividing the current sequence into a plurality of subsequences according to the division result of the beam current fluctuation sequence is as follows:

[0022] The beam current fluctuation sequence is clustered by the DBSCAN clustering algorithm, and the values of the preset neighborhood radius and minPts are set; all the divided subsequences are labeled in time sequence; the beam current fluctuation sequence and the current subsequence have the same number of subsequences, and the number of elements in the same labeled subsequence is the same.

[0023] In one embodiment, the method for obtaining the corresponding mean square error by linear fitting the same labeled subsequence corresponding to the beam current fluctuation sequence and the current sequence is as follows:

[0024] The same labeled subsequence of the beam current fluctuation sequence and the current sequence is taken as input, the field current is taken as the independent variable, and the beam current fluctuation factor is taken as the dependent variable, each time corresponds to a data point, and the linear fitting of all data points of each labeled subsequence is performed to obtain the current-beam current straight line; the mean square error of the current-beam current straight line is calculated.

[0025] In one embodiment, the method for obtaining the current influence intensity at the current time according to the difference between the field current in all subsequences of the current sequence and the overall field current of the current sequence and the mean square error is as follows:

[0026] , represents the mean value of the field current corresponding to the kth subsequence, represents the mean value of all field currents of the current sequence, represents the mean square error of the current-beam current straight line corresponding to the kth subsequence, represents the number of divided subsequences, This indicates the intensity of the current's influence at the current moment.

[0027] In one embodiment, the method for improving the proportional term of the PID control algorithm based on the intensity of the current influence is as follows:

[0028] , , For the improved proportional term, For the initially set ratio, For mapping functions, This indicates the intensity of the current's influence at the current moment.

[0029] Secondly, embodiments of this application also provide a medical cyclotron beam alignment adjustment system, 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 of the above-described medical cyclotron beam alignment adjustment methods.

[0030] The beneficial effects of this application are as follows: This application proposes a method and system for beam alignment adjustment in a medical cyclotron accelerator. Addressing the problem of evaluating the stability of the magnetic field and beam in a medical cyclotron accelerator, it uses autocorrelation analysis and Pearson correlation analysis algorithms to reflect the comprehensive characteristics of magnetic field and beam stability, solving the problem of difficulty in quantifying beam stability. Regarding the impact of excitation current changes on beam stability, it uses the DBSCAN density clustering algorithm and least squares linear fitting to reflect the average impact of excitation current changes on beam stability, eliminating the influence of fluctuations at single data points. By improving the PID control algorithm and dynamically adjusting the proportional term, it achieves real-time feedback and adjustment of excitation current changes, optimizes magnetic field changes, and achieves more efficient and stable nuclide production. Attached Figure Description

[0031] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A flowchart of a medical cyclotron beam alignment adjustment method provided in one embodiment of this application;

[0033] Figure 2 This is a schematic diagram of the clustering of beam turbulence sequences. Detailed Implementation

[0034] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined object, the following describes in detail the specific implementation, structure, features and effects of the medical cyclotron beam centering adjustment method and system according to the present application, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0036] A medical cyclotron beam centering adjustment method embodiment:

[0037] The following specifically describes the specific scheme of the medical cyclotron beam centering adjustment method provided by the present application in combination with the accompanying drawings.

[0038] Please refer to Figure 1 which shows a medical cyclotron beam centering adjustment method flowchart provided by one embodiment of the present application, the method comprising the following steps:

[0039] Step S001, based on different sensors to collect the magnetic field sequence, beam sequence and current sequence at the current time.

[0040] A magnetic field sensor is installed near the acceleration cavity of the medical cyclotron to collect magnetic field strength data; a beam probe is installed in the beam extraction area of the medical cyclotron to collect beam intensity data; a current sensor is installed in the magnet power supply control part of the medical cyclotron to collect magnet power excitation current data.

[0041] The preset number of magnetic field strength, beam intensity and excitation current before the current time are normalized to eliminate the influence of dimension, and the preset number of U magnetic field strength, beam intensity and excitation current are sorted to obtain the magnetic field sequence, beam sequence and current sequence at the current time.

[0042] In this embodiment, the collection interval of the magnetic field sensor, beam probe and current sensor is 50Hz, the three kinds of data in the above are collected and normalized in real time, the selected normalization method is linear normalization method, for each kind of data, the data collected within 5 minutes before the current time is sorted in ascending order of time to form the magnetic field sequence, beam sequence and current sequence at each collection time, it should be noted that if the current collection time is less than five minutes, all the data collected before the current time are sorted and the mean is filled in the leftmost side to ensure the fixed number of elements in the sequence.

[0043] At this point, the magnetic field sequence, the beam current sequence, and the current sequence are obtained.

[0044] In step S002, the beam current fluctuation factor is obtained according to the difference in the lag number corresponding to the maximum autocorrelation coefficient of the magnetic field sequence and the beam current sequence, the correlation between the magnetic field sequence and the beam current sequence, and the difference in the maximum autocorrelation coefficient.

[0045] The beam current is a high-speed charged particle flow generated by an accelerator, and the magnetic field is responsible for guiding and focusing these particles. During the acceleration process, the modulation degree of the magnetic field directly affects the stability and focusing degree of the beam current. A magnetic field with good modulation degree can ensure the stability of the beam current in the accelerator, reduce the scattering and loss of particles, and thus improve the quality and yield of the beam current. On the contrary, insufficient modulation degree will lead to unstable beam current, increase the scattering of particles, and reduce the focusing degree of the beam current, thereby affecting the production efficiency and quality of the nuclide.

[0046] Since the stability of the magnetic field and the beam current in the medical cyclotron is crucial for the quality of the nuclide production, calculating the autocorrelation coefficient can reveal the inherent periodicity of the magnetic field and the beam current, thereby identifying the stability problems of the magnetic field and the beam current intensity. In this embodiment, the initial value of the lag number is set to 2, and the step size of the lag number is 2, which gradually increases and stops growing after increasing to half the length of the magnetic field sequence.

[0047] The stability of the magnetic field and the beam current is affected by various dynamic factors, which can cause periodicity in the focusing degree of the beam current. The maximum value a of the autocorrelation coefficient of the magnetic field sequence at all lag numbers is extracted to quantify the maximum periodicity of the magnetic field intensity. Based on the same method, the autocorrelation coefficient of the beam current sequence is analyzed, and the maximum value b of the autocorrelation coefficient of the beam current sequence at all lag numbers is extracted to quantify the maximum periodicity of the beam current intensity.

[0048] Since the change of the excitation current may have a delayed effect on the stability of the beam current, the difference in the lag number when the autocorrelation coefficients of the magnetic field sequence and the beam current sequence reach the maximum value is calculated as the most relevant lag number difference c. Then, using the magnetic field sequence and the beam current sequence as input, the Pearson correlation coefficient d between the magnetic field sequence and the beam current sequence is output using the Pearson correlation analysis algorithm to analyze the correlation between the magnetic field intensity and the beam current intensity.

[0049] The magnetic field beam current stability is obtained according to the maximum values of the autocorrelation coefficients of the magnetic field sequence and the beam current sequence. The average of the maximum values of the autocorrelation coefficients of the magnetic field sequence at all lag numbers and the maximum values of the autocorrelation coefficients of the beam current sequence at all lag numbers is taken as the magnetic field beam current stability.

[0050] The beam fluctuation factor at the current time is obtained according to the magnetic field beam stability at the current time, the difference of the most relevant lag number, and the correlation of the magnetic field sequence and the beam sequence.

[0051] The beam fluctuation factor is negatively correlated with the magnetic field beam stability, the correlation of the magnetic field sequence and the beam sequence, and is positively correlated with the difference of the most relevant lag number.

[0052] It should be noted that the positive correlation means that when one variable increases, the other variable also increases, and the two variables change in the same direction. When one variable changes from large to small or from small to large, the other variable also changes from large to small or from small to large. The specific relationship is determined by actual application, and the present application does not make special limitations.

[0053] It should be noted that the negative correlation means that when one variable increases, the other variable decreases, and the two variables change in opposite directions. When one variable changes from large to small or from small to large, the other variable also changes from small to large or from large to small. The specific relationship is determined by actual application, and the present application does not make special limitations.

[0054] Preferably, in the present embodiment, the expression of the beam fluctuation factor is:

[0055] represents the difference of the most relevant lag number of the magnetic field sequence and the beam sequence, represents the magnetic field beam stability, represents the correlation of the magnetic field sequence and the beam sequence, represents the beam fluctuation factor at each time.

[0056] Wherein, the greater the magnetic field beam stability, the stronger the similarity between the magnetic field and the beam intensity in time, that is, the more stable the changes of the magnetic field and the beam, and the smaller the beam fluctuation factor. The difference of the most relevant lag number represents the time difference when the magnetic field and the beam stability indicators reach the peak value under different lag numbers. The greater the difference of the most relevant lag number, the greater the asynchronization between the magnetic field and the beam in time, and the greater the beam fluctuation. The correlation of the magnetic field sequence and the beam sequence reflects the influence degree of the magnetic field change on the beam stability. The greater the value, the stronger the linear correlation between the magnetic field and the beam intensity, and the smaller the beam fluctuation, and the smaller the beam fluctuation factor. The beam fluctuation factor is a comprehensive reflection of the stability of the magnetic field and the beam. The smaller the beam fluctuation factor, the more stable the beam, the smaller the fluctuation, and the higher the production efficiency and quality of the nuclide.

[0057] Thus, the beam fluctuation factor at each time during the operation of the medical cyclotron is obtained.

[0058] ​Step S003: The beam turbulence factor is used to form a beam turbulence sequence. After dividing the beam turbulence sequence, the current sequence is also divided. Based on the current turbulence sequence and the current sequence fitted with a straight line, the intensity of the current influence at the current moment is obtained according to the difference between the excitation current in all sub-sequences and the overall excitation current of the current sequence, as well as the mean square error.

[0059] According to Ampere's circuital law, a current in a conductor generates a static magnetic field. Changes in the current directly affect the strength of the magnetic field, thus influencing the trajectory of particles in the accelerator. Changes in the excitation current affect the magnetic field strength, thereby affecting the beam stability and focusing. The beam turbulence factor describes beam stability. Since the magnetic field strength is directly affected by the excitation current, the beam turbulence factor is indirectly related to the current. If the excitation current changes, leading to changes in the magnetic field strength, it will affect the beam stability, thus affecting the value of the beam turbulence factor.

[0060] A beam turbulence factor is calculated at each acquisition moment, and the beam turbulence factors of the previous U acquisition moments are sorted in ascending order of time to obtain the beam turbulence sequence. Since the beam turbulence factor reflects different states of beam stability, and these states may exhibit different local features and patterns, the beam turbulence sequence is divided based on the beam turbulence factor.

[0061] Using the beam turbulence sequence as input, the DBSCAN clustering algorithm is used to cluster the beam turbulence sequence. The clustering results are as follows: Figure 2 As shown, the neighborhood radius is 0.5 and minPts is 40, thus dividing the beam turbulence sequence into several subsequences. The current sequence is similarly divided, with each subsequence of the beam turbulence sequence numbered chronologically. Since the current sequence and the beam turbulence sequence are of equal length, the current sequence is divided according to the division result of the beam turbulence sequence. The beam turbulence sequence and the current subsequence have the same number of subsequences, and subsequences with the same number of elements have the same number of elements. For example, if the beam turbulence sequence is divided into sequences of length 4, length 5, and length 3, then the current sequence is also divided into sequences of length 4, length 5, and length 3.

[0062] To ensure an accurate quantitative understanding of the cluster characteristics of the beam turbulence sequence and to ensure the identification of the stability characteristics within each subsequence, the mean value of the excitation current in each subsequence of the current sequence is calculated, and then the mean value of all excitation currents in the current sequence is calculated.

[0063] Since the current change will cause the beam to oscillate, in order to ensure that the specific influence of the excitation current change on the beam stability can be accurately quantified, the beam oscillation sequence and the same labeled subsequence of the current sequence are taken as the input, the excitation current is taken as the independent variable, the beam oscillation factor is taken as the dependent variable, each time corresponds to a data point, and the straight line fitting method is used to obtain the current beam straight line. In this embodiment, the straight line fitting method is the least square method. The mean square error of the current beam straight line is calculated.

[0064] According to the difference between the excitation current and the overall excitation current of the current sequence in all sub-sequences and the mean square error of the current beam straight line, the current influence intensity at the current time is obtained, and the expression is:

[0065] The mean value of the excitation current corresponding to the kth sub-sequence is represented by The mean value of all excitation currents of the current sequence is represented by The mean square error of the current beam straight line corresponding to the kth sub-sequence is represented by The number of divided sub-sequences is represented by The current influence intensity at the current time is represented by

[0066] The difference between the current mean value of the kth sub-sequence and the overall current mean value reflects the deviation of the current change in the specific sub-sequence relative to the overall average level, and the greater the value, the greater the influence of the excitation current change on the beam stability in the sub-sequence. The deviation between the fitted straight line and the actual data points is measured, and the smaller the value means that in the sub-sequence, the excitation current change and the beam oscillation have a strong linear relationship, that is, the slight change of the excitation current can significantly affect the stability of the beam, and the current influence intensity is greater. The current influence intensity describes the average influence of the excitation current change on the beam stability in the medical cyclotron, and the greater the value, the greater the influence of the slight change of the current on the beam stability.

[0067] At this point, the current influence intensity at the current time is obtained.

[0068] In step S004, the proportional term is improved according to the current influence intensity, and the excitation current is controlled based on this.

[0069] According to the analyzed current influence intensity B, a PID control algorithm is designed to regulate the magnetic field in the medical accelerator. The PID algorithm will dynamically adjust the excitation current based on the influence of the excitation current change on the beam stability to maintain the stability and focusing degree of the beam. The design steps of the control algorithm are as follows:

[0070] ​The parameters of the PID control algorithm are set, and in this embodiment, P = 1.5, I = 0.25, and D = 0.02. The proportional (P) term is responsible for reducing the deviation, the integral (I) term is responsible for eliminating the steady-state error, and the derivative (D) term is responsible for predicting future trends and reducing the overshoot of the system. Due to the influence of the field current on the beam stability, the proportional term of the PID control algorithm is improved, and the specific improvement relationship is , wherein, is the improved proportional term, is the initially set proportional term, is a mapping function, and the tanh function is used to map B into to limit the size of and make it can be dynamically adjusted according to the actual value of the current influence intensity B. When the B value is large, it means that the change of the field current has a significant impact on the beam stability. At this time, the increase of the value will enhance the response ability of the controller to the change of the field current. On the contrary, when the B value is small, that is, the change of the field current has little effect on the beam stability, the decrease of the value will avoid over-adjusting the field current, thereby reducing the overshoot and oscillation of the system.

[0071] The proportional term P' of the PID controller is dynamically adjusted, and according to the adjusted proportional term P', the integral term I and the derivative term D, a control signal is output. The control signal output by the PID is converted into an analog signal by a digital-to-analog (D / A) converter and acts on a magnetic field adjusting device, such as a tunable magnet or a magnetic field adjusting coil, to maintain the stability of the magnetic field. The system continuously monitors the stability of the magnetic field and the beam, and according to the real-time data feedback, the parameters of the PID controller are continuously adjusted to optimize the magnetic field control effect.

[0072] Based on the same inventive concept as the above method, the embodiments of the present application also provide a medical cyclotron beam centering adjustment system, which comprises 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 any one of the above medical cyclotron beam centering adjustment methods are implemented.

[0073] It should be noted that the above-described embodiments 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 embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing embodiments, or make equivalent substitutions for some technical features. These modifications or substitutions do not change the essence of the corresponding technical solutions, and should be included in the protection scope of the present application.

[0074] The various embodiments described in this specification are presented by way of example, and each embodiment is not necessarily composed of all features described with respect to other embodiments.

Claims

1. A method of medical cyclotron beam alignment adjustment, characterized by, The method includes the following steps: The magnetic field sequence, beam sequence, and current sequence are collected at the current moment based on different sensors; For both the magnetic field sequence and the beam sequence, the autocorrelation coefficients of the sequences under different lag numbers are calculated, and the most relevant lag number difference is obtained based on the difference in lag numbers under the autocorrelation coefficients. The magnetic field-beam stability is obtained based on the maximum autocorrelation coefficient difference between the magnetic field sequence and the beam sequence. The beam turbulence factor at the current moment is obtained based on the most relevant lag number difference, the magnetic field-beam stability, and the correlation between the magnetic field sequence and the beam sequence. The beam turbulence factor is negatively correlated with the magnetic field-beam stability and the correlation between the magnetic field sequence and the beam sequence, and positively correlated with the most relevant lag number difference. A beam turbulence sequence is constructed by a predetermined number of beam turbulence factors prior to the current moment. All beam turbulence factors in the beam turbulence sequence are clustered, divided into several subsequences and labeled. The current sequence is divided into several subsequences according to the division result of the beam turbulence sequence. The corresponding subsequences with the same label in the beam turbulence sequence and the current sequence are fitted with a straight line to obtain the corresponding mean square error. The intensity of the current influence at the current moment is obtained based on the difference between the excitation current in all subsequences of the current sequence and the overall excitation current of the current sequence, as well as the mean square error. The proportional term of the PID control algorithm is improved based on the influence intensity of the current. The excitation current is controlled based on the improved proportional, integral and derivative terms, and the proportional term is adjusted in real time to optimize the magnetic field control effect. The method for obtaining the mean square error by performing linear fitting on the subsequences with the same label corresponding to the beam turbulence sequence and the current sequence is as follows: The subsequences with the same labels as the current sequence are used as input, with the excitation current as the independent variable and the beam turbulence factor as the dependent variable. Each time point corresponds to a data point. All data points of the subsequence corresponding to each label are fitted with a straight line to obtain the current beam straight line. The mean square error of the current beam straight line is calculated. The method for obtaining the current influence intensity at the current moment based on the difference between the excitation current in all subsequences of the current sequence and the overall excitation current of the current sequence, as well as the mean square error, is as follows: , denotes the mean value of the excitation current corresponding to the kth sub-sequence, denotes the mean value of all excitation currents of the current sequence, denotes the mean square error of the current beam straight line corresponding to the kth sub-sequence, denotes the number of the divided sub-sequences, denotes the current time current influence intensity; The method for improving the proportional term of the PID control algorithm based on the influence intensity of the current is as follows: , , is an improved proportional term, is an initially set proportional term, is a mapping function, represents the current time's current influence intensity.

2. A method of beam centering adjustment for a medical cyclotron as defined in claim 1, wherein Collect the magnetic field strength, beam current strength, and excitation current at a preset number of times prior to the current time, and sort the magnetic field strength, beam current strength, and excitation current to obtain the magnetic field sequence, beam current sequence, and current sequence for each collection time.

3. A method of beam centering adjustment for a medical cyclotron as defined in claim 1, wherein The method for calculating the autocorrelation coefficients of the magnetic field sequence and the beam sequence under different lag numbers, and obtaining the most relevant lag number difference based on the lag number difference under the autocorrelation coefficients, is as follows: Multiple lag numbers are preset, with the maximum value of the lag number being half the value of the sequence. The lag number corresponding to the maximum autocorrelation coefficient of the magnetic field sequence is denoted as the first lag number. The lag number corresponding to the maximum autocorrelation coefficient of the beam sequence is denoted as the second lag number; The absolute value of the difference between the first lag and the second lag is taken as the most relevant lag difference.

4. A method of beam centering adjustment for a medical cyclotron as defined in claim 1, wherein The method for obtaining magnetic field beam stability based on the maximum autocorrelation coefficient difference between the magnetic field sequence and the beam sequence is as follows: The maximum value of the autocorrelation coefficient of the magnetic field sequence at all lags is taken as the magnetic field-beam stability, and the average of the maximum values of the autocorrelation coefficient of the beam sequence at all lags is taken as the magnetic field-beam stability.

5. A method of beam centering adjustment for a medical cyclotron as defined in claim 1, wherein The method for clustering all beam oscillation factors in the beam oscillation sequence, dividing the beam oscillation sequence into a plurality of subsequences and labeling, and dividing the current sequence into a plurality of subsequences according to the division result of the beam oscillation sequence is as follows: The beam oscillation sequence is clustered by the DBSCAN clustering algorithm, and the values of the preset neighborhood radius and minPts are set; all the divided subsequences are labeled in time sequence; the beam oscillation sequence and the current subsequence have the same number of subsequences, and the same labeled subsequence has the same number of elements.

6. A medical cyclotron beam centering adjustment system comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, The processor executes the computer program to realize the steps of the medical cyclotron beam centering adjustment method according to any one of claims 1-5.

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