A method and system for measuring the sliding phase of a beam in a medical cyclotron accelerator.

Abstract

This application relates to the field of plasma technology, specifically to a method and system for measuring beam slip phase in a medical cyclotron accelerator. The method includes: acquiring beam intensity and obtaining a target quantity; dividing the target quantity into two parts to obtain a symmetrical target quantity; obtaining an interference source sequence based on the front and symmetrical target quantities; obtaining an interference intensity based on the front and rear target quantities; processing the interference source sequence to obtain an interference source intensity sequence; processing the interference source intensity sequence to obtain the interference source fluctuation intensity, thereby determining the upper limit of the beam intensity; determining the beam intensity ratio based on the upper limit of the beam intensity and all beam intensities of the target quantity; obtaining a slip phase sine value based on the relationship between the phase difference and the beam intensity ratio; recording the current increase; and calculating the beam slip phase based on the slip phase sine value and the current increase value to complete the beam slip phase measurement. This application improves the accuracy of beam slip phase measurement results.

Description

Technical Field

[0001] This application relates to the field of plasma technology, specifically to a method and system for measuring the sliding phase of a medical cyclotron beam. Background Technology

[0002] Beam phase slip refers to the deviation between the rotational phase of charged particles moving in a circular motion within a magnetic field in a medical cyclotron and the changing phase of the high-frequency magnetic field, caused by inhomogeneities in the magnetic field or instabilities in the high-frequency electric field. This deviation affects the acceleration efficiency of the particles, thus impacting the beam quality and the final acceleration effect. To ensure effective particle acceleration, phase slip measurements are necessary for the particle beam in the medical cyclotron to adjust the high-frequency magnetic field phase and achieve better particle acceleration.

[0003] Existing methods obtain the existence and magnitude of the slip phase based on the asymmetry of the current change. This method of measuring the slip phase involves frequently adjusting the current and measuring the beam intensity, which is cumbersome and time-consuming. Frequent adjustments to the superconducting coil current may affect the stability of the accelerator, thereby affecting the accuracy of the measurement results. Therefore, in the existing methods for measuring the slip phase of the beam in medical cyclotrons, the stability of the accelerator decreases due to frequent adjustments to the superconducting coil current, which in turn affects the accuracy of the final measurement results. Summary of the Invention

[0004] To address the technical problem of inaccurate sliding phase measurement, this application provides a method and system for measuring sliding phase in a medical cyclotron beam. The specific technical solution adopted is as follows:

[0005] In a first aspect, this application proposes a method for measuring the sliding phase of a beam in a medical cyclotron accelerator, the method comprising the following steps:

[0006] The beam intensity on the radial target at each moment is collected, and the vector formed by all beam intensities is recorded as the target quantity;

[0007] The target quantity is divided into two parts, denoted as the front target quantity and the rear target quantity. The rear target quantity is symmetrically processed to obtain the symmetrical target quantity. The interference source sequence is determined based on the difference in beam intensity at the same position of the front and rear target quantities. The interference intensity in the acceleration region is obtained by analyzing the difference in the mean beam intensity of the front and rear target quantities. The interference source intensity sequence is determined by the difference between the interference source sequence and the interference intensity in the acceleration region. The interference source intensity sequence is processed using the 3 sigma principle to obtain the interference source fluctuation intensity. The upper limit of the beam intensity is determined by multiplying the interference source fluctuation intensity by the preset intensity.

[0008] The beam intensity ratio is determined based on the upper limit of beam intensity and all beam intensities of the target quantity; the relationship between the beam intensity ratio and the phase difference is obtained by analyzing the beam width of the bundle; the relationship is then substituted into the sine formula of the phase difference to obtain the sliding phase sine value.

[0009] Record the current increase when the beam intensity reaches the upper limit of the beam intensity; calculate the beam slip based on the slip sine value and the current increase value to complete the beam slip measurement.

[0010] In the above scheme, this application obtains a radial target data vector by measuring the beam intensity through a radial target; by utilizing the symmetry of the radial target data vector signal, an interference source sequence is obtained, and the interference source characteristics during beam intensity measurement are extracted; considering the asymmetry of the radial target data vector caused by the asymmetric acceleration of particles when the beam passes through the acceleration zone of the medical cyclotron, the interference intensity in the acceleration zone is calculated, and the interference source sequence is processed with the acceleration zone interference intensity to obtain an interference source intensity sequence, which characterizes the beam intensity generated by the interference source in the medical cyclotron; further, the interference source fluctuation intensity is calculated through the interference source intensity sequence, and the upper limit of the beam intensity is set accordingly to adjust the superconducting coil current control conditions during beam slip phase measurement; finally, the measurement data of beam slip phase is obtained through the obtained superconducting coil current control conditions, and the magnitude of the beam slip phase is calculated. In this application, interference noise from the beam intensity signal is extracted. The superconducting coil current control conditions are adjusted to ensure that the interference noise does not affect the final result. This reduces the frequency of superconducting coil current adjustments and avoids the problem of accelerator stability degradation caused by frequent superconducting coil current adjustments, thereby improving the accuracy of beam slip measurement results.

[0011] In one embodiment, the method of dividing the target amount into two parts, denoted as the pre-target amount and the post-target amount, and symmetrically processing the post-target amount to obtain the symmetrical target amount is as follows:

[0012] The target quantity is evenly divided in the middle, with the front part being the front target quantity and the back part being the back target quantity; the back target quantity is then processed to obtain a symmetrical target quantity.

[0013] In one embodiment, the method for determining the interference source sequence based on the beam intensity difference at the same position between the pre-target and post-target quantities is as follows:

[0014] The absolute value of the difference between the beam intensity at the same position in the front target quantity and the symmetrical target quantity and the constant 2 are used as the element value; the sequence of element values ​​arranged in the same position order is used as the interference source sequence.

[0015] In one embodiment, the method of analyzing the difference in the average beam intensity of the pre-targeting and post-targeting quantities to obtain the interference intensity in the acceleration region, and determining the interference source intensity sequence by the difference between the interference source sequence and the interference intensity in the acceleration region, is as follows:

[0016] Let the ratio of the difference between the mean of the front target element and the mean of the rear target element to the constant 2 be taken as the interference intensity in the acceleration zone.

[0017] The sequence obtained by subtracting the value of each element in the interference source sequence from the interference intensity in the acceleration region is used as the interference source intensity sequence.

[0018] In one embodiment, the method for processing the interference source intensity sequence using the 3 sigma principle to obtain the interference source fluctuation intensity is as follows:

[0019] Calculate the mean and standard deviation of the sequence values ​​in the interference source intensity sequence, and let the sum of the mean and three times the standard deviation be taken as the interference source fluctuation intensity.

[0020] In one embodiment, the method for determining the beam intensity ratio based on the upper limit of beam intensity and all beam intensities of the target quantity is as follows:

[0021] The average beam intensity of the target quantity at all times is calculated as the beam intensity of the target quantity. The ratio of the upper limit of the beam intensity to the beam intensity of the target quantity is denoted as the beam intensity ratio.

[0022] In one embodiment, the relationship between the beam intensity ratio and phase difference obtained by analyzing the beam bundle width is as follows:

[0023] , 1 is the beam intensity ratio, and 2 is the definite integral of the sine function from 0 to 180°. It is a sine function from 0 to definite integral, It is the phase difference between the beam rotation phase and the accelerating electric field phase.

[0024] In one embodiment, the method for substituting the relational expression into the sine formula for the phase difference to obtain the sliding phase sine value is as follows:

[0025] , It is the beam intensity ratio. This is the value of the sliding phase sine.

[0026] In one embodiment, the method for calculating the beam slippage based on the slippage sine and the current increase when the beam intensity reaches the upper limit of the beam intensity is as follows:

[0027] When the superconducting coil current is reduced, the increase in current when the beam current intensity reaches its upper limit is recorded, denoted as . When increasing the superconducting coil current, record the increase in current when the beam current intensity reaches its upper limit, denoted as ; ;

[0028] The expression for beam slip phase:

[0029] , It is the size of the beam slip phase. It is the inverse function of the sine function. The value is the sine of the sliding phase. and This represents the increase in current for the two superconducting coils.

[0030] Secondly, embodiments of this application also provide a medical cyclotron beam sliding phase measurement 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 sliding phase measurement methods.

[0031] The beneficial effects of this application are as follows:

[0032] This application measures beam intensity using a radial target to obtain a radial target data vector. Leveraging the symmetry of the radial target data vector signal, it calculates an interference source sequence and extracts interference source characteristics during beam intensity measurement. Addressing the asymmetry in the radial target data vector caused by asymmetric particle acceleration as the beam passes through the acceleration zone of a medical cyclotron, it calculates the interference intensity in the acceleration zone and processes the interference source sequence to obtain an interference source intensity sequence, characterizing the beam intensity generated by interference sources within the medical cyclotron. Furthermore, it calculates the interference source fluctuation intensity using the interference source intensity sequence and sets an upper limit for beam intensity to adjust the superconducting coil current control conditions during beam slip measurement. Finally, it obtains the beam slip measurement data using the obtained superconducting coil current control conditions and calculates the beam slip magnitude. Notably, because this application extracts interference source noise from the beam intensity signal, it adjusts the superconducting coil current control conditions without affecting the final results, reducing frequent adjustments to the superconducting coil current and avoiding the accelerator stability degradation caused by frequent superconducting coil current adjustments, thereby improving the accuracy of beam slip measurement results. Attached Figure Description

[0033] 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.

[0034] Figure 1 A flowchart of a medical cyclotron beam sliding phase measurement method provided in one embodiment of this application;

[0035] Figure 2 This is a schematic diagram of a cyclotron. Detailed Implementation

[0036] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a medical cyclotron beam sliding phase measurement method and system proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0037] 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 pertains.

[0038] An embodiment of a method for measuring the sliding phase of a beam in a medical cyclotron accelerator:

[0039] The following description, in conjunction with the accompanying drawings, details a specific scheme for measuring the sliding phase of a medical cyclotron beam provided in this application.

[0040] Please see Figure 1 The diagram illustrates a flowchart of a medical cyclotron beam sliding phase measurement method according to an embodiment of this application. The method includes the following steps:

[0041] Step S001: Collect the beam intensity on the radial target at each moment, and denote the vector formed by all beam intensities as the target quantity.

[0042] Because beam slippage leads to an asymmetric response of beam intensity to changes in superconducting coil current, existing methods use this asymmetry to determine the magnitude of beam slippage. However, this requires changing the superconducting coil current, which can easily reduce the stability of the medical cyclotron, leading to deviations in the measurement results and affecting their accuracy.

[0043] The intensity of the beam from a medical cyclotron is measured using a radial target. The result is the beam signal intensity, which represents the number of particles striking the radial target within the cyclotron at a given moment. A schematic diagram of the cyclotron is shown below. Figure 2 As shown. Figure 2 1 is the trajectory of the water flow, 2 is the D-shaped box of the medical cyclotron, 3 is the electric field line of the medical cyclotron, and 4 is the radial target placed in the medical cyclotron.

[0044] In this system, the radial target is perpendicular to the accelerating electric field. Therefore, the time it takes for the beam cluster to reach the radial target is one-quarter of the particle's rotational cycle. The moment the beam cluster reaches the radial target coincides with the moment the radio frequency signal of the medical cyclotron reaches its maximum value. After the beam cluster reaches the radial target, its duration is one-half of the particle's rotational cycle, and the data acquisition duration is also one-half of the particle's rotational cycle. In other words, data acquisition from the radial target begins when the signal value reaches its maximum value, and the acquisition period is one-half of the particle's rotational cycle.

[0045] In this embodiment, the medical cyclotron uses an accelerating frequency of A = 75 MHz for acceleration. The sampling frequency of the radial target, B = 2000 times that of the medical cyclotron, is used to measure the beam intensity. The sampling frequency of the radial target is C = 150 GHz. Half a period of particle rotation is... .

[0046] The collected radial target data are used to construct a vector, denoted as the target quantity, with a length of... The nth element represents the beam intensity at time n.

[0047] At this point, the beam intensity at each moment has been obtained.

[0048] Step S002: Divide the target quantity into two parts, obtain the symmetrical target quantity, obtain the interference source sequence based on the front target quantity and the symmetrical target quantity, obtain the interference intensity based on the front target quantity and the rear target quantity, process the interference source sequence to obtain the interference source intensity sequence, process the interference source intensity sequence to obtain the interference source fluctuation intensity, and thus determine the upper limit of the beam intensity.

[0049] The beam in the accelerator exists in the form of plasma, called a beam cluster. In the absence of environmental interference, after the beam cluster passes through the acceleration zone of the medical cyclotron, its energy is controlled by the radio frequency signal that can accelerate the particles in the acceleration zone. The greater the energy provided by the radio frequency signal in the acceleration zone, the greater the total energy of the particles in the corresponding region inside the beam cluster, and the greater the beam intensity measured after it hits the radial target.

[0050] Since the radio frequency signal is symmetrical within its period, the target quantity generated under its control, in the absence of interference sources, is also a symmetrical vector. Therefore, the asymmetrical signal portion of the target quantity can be considered as beam intensity interference generated by interference sources inside the cyclotron.

[0051] The target quantity is divided in the middle, with the front part being the front target quantity and the back part being the back target quantity. In this embodiment, the first 500 beam intensities constitute the front target quantity, and the last 500 beam intensities constitute the back target quantity. Furthermore, the back target quantity is processed with centrosymmetry, which means swapping the first element with the last element, the second element with the second to last element, and so on, until the 250th and 251st elements are swapped. The resulting vector is denoted as the symmetrical target quantity.

[0052] The differences between elements at the same position in the pre-target quantity and the symmetrical target quantity constitute the interference source sequence. This interference source sequence characterizes the influence of internal interference sources of the cyclotron on the beam intensity measured on the radial target. In this embodiment, the ratio of the absolute value of the difference between elements at the same position in the pre-target quantity and the symmetrical target quantity to a constant 2 is used as the element value of the interference source sequence.

[0053] Ideally, beam particles spend an extremely short time passing through the acceleration zone, so the intensity of the accelerating electric field acting on the particles can be considered constant. In this case, without interference, the target quantity should be a strictly symmetrical vector. However, inside actual medical cyclotrons, the accelerating electric field is altered by radio frequency signals as the beam particles pass through the acceleration zone. Therefore, the acceleration of the particle corresponding to the earlier target quantity gradually increases as it passes through the acceleration zone, while the acceleration of the particle corresponding to the later target quantity gradually decreases. Consequently, the kinetic energy of the particle corresponding to the earlier target quantity is greater than that of the particle corresponding to the later target quantity. This results in the target quantity not being a strictly symmetrical vector; the beam intensities represented by the earlier and later target quantities differ in magnitude overall.

[0054] Therefore, the interference intensity in the acceleration zone is calculated for the interference source sequence to remove the influence of asymmetric acceleration of particles in the acceleration zone on the feature extraction of the interference source.

[0055] Calculate the mean of all elements in the front target quantity and the mean of all elements in the back target quantity, and let the ratio of the difference between the mean of the front target quantity elements and the mean of the back target quantity elements to the constant 2 be taken as the interference intensity in the acceleration zone.

[0056] The mean values ​​of the pre-target quantity and the post-target quantity represent the corresponding beam intensity, respectively. The difference represents the beam intensity difference between the two under the interference of the acceleration zone, which represents the beam intensity interference caused by asymmetric acceleration in the acceleration zone to the feature extraction of the interference source. Finally, the value is divided by 2 for numerical processing to obtain the interference intensity of the acceleration zone. The larger the value, the more beam intensity features represented by the interference source sequence are caused by the asymmetric acceleration of particles in the acceleration zone.

[0057] Subtract the acceleration region interference intensity from each element value in the interference source sequence to obtain the interference source intensity sequence, which characterizes the beam intensity fluctuation caused by the interference source in the target quantity.

[0058] The interference source intensity sequence is the interference signal caused by the interference source to the beam intensity. As a noise signal, the interference to the beam intensity is relatively random. Therefore, in this embodiment, the maximum fluctuation value of the interference source is estimated according to the 3-sigma principle, and the maximum fluctuation value is recorded as the interference source fluctuation intensity. The specific method is as follows:

[0059] Calculate the mean and standard deviation of the sequence values ​​in the interference source intensity sequence, and let the sum of the mean and three times the standard deviation be taken as the interference source fluctuation intensity.

[0060] According to the 3 sigma principle, the fluctuation range of data is between its mean and plus or minus three times the standard deviation. Therefore, in this embodiment, the mean plus three times the standard deviation is taken as the maximum fluctuation value caused by the interference source to the beam intensity measurement. The larger this value is, the larger the range of beam intensity should be adjusted when performing beam phase slip measurement in order to eliminate the influence of the interference source on the beam phase slip measurement.

[0061] When the adjusted beam intensity range is greater than n times the interference source fluctuation intensity, the interference source fluctuation will not affect the beam intensity range. In this embodiment, n is taken as an empirical value of 50.

[0062] Finally, during beam sliding phase measurement, a medical cyclotron is run, and the intensity of the interference source fluctuation is calculated according to the scheme described in this embodiment. The result is multiplied by an empirical constant n, and the value obtained is recorded as the upper limit of the beam intensity, which is used to guide the adjustment of the superconducting coil current during beam sliding phase measurement.

[0063] Thus, the upper limit of beam intensity was obtained.

[0064] Step S003: Determine the beam intensity ratio based on the upper limit of beam intensity and all beam intensities of the target quantity; obtain the relationship between the beam intensity ratio and the phase difference by analyzing the beam width of the bundle; substitute the relationship into the sine formula of the phase difference to obtain the sliding phase sine value.

[0065] After obtaining the upper limit of beam intensity according to the above steps, the average value of beam intensity of the target quantity at all times is calculated as the beam intensity of the target quantity. The ratio of the upper limit of beam intensity to the beam intensity of the target quantity is recorded as the beam intensity ratio.

[0066] In the subsequent measurement of beam slip phase, the magnetic field is controlled by adjusting the superconducting coil current. The magnetic field controls the phase of the beam rotation. The change in the beam rotation phase causes a phase difference between the beam rotation phase and the phase of the accelerating electric field. The phase difference causes the acceleration effect of the accelerating electric field to decrease, which in turn causes the beam intensity to decrease until the beam intensity decreases to meet the beam intensity ratio.

[0067] The beam intensity ratio represents the magnitude of the beam slip phase generated by the active control magnetic field. After the active control magnetic field is obtained by calculating the beam intensity ratio, a phase difference appears between the beam rotation phase and the accelerating electric field phase.

[0068] The phase difference between the beam rotation phase and the accelerating electric field phase is called the slip phase at any radius of the particle. This phase difference is needed when calculating the magnitude of the beam slip phase using measurement data; therefore, it is necessary to calculate the sine value of this phase difference. .

[0069] Because artificially controlled beam slippage prevents the acceleration of beam particles within the phase difference between the beam rotation phase and the accelerating electric field phase, these particles cannot be measured by the radial target, leading to a decrease in beam intensity. The accelerator beam is a cluster with a certain phase width. In a cyclotron accelerator, the acceleration region's acceleration of the beam lasts for half a cycle and is sinusoidal. Therefore, the phase width of the accelerator beam is 180°, and the energy distribution of its beam particles is sinusoidal. Thus, the relationship between beam intensity ratio and phase difference is:

[0070] , 1 is the beam intensity ratio, and 2 is the definite integral of the sine function from 0 to 180°. It is a sine function from 0 to definite integral, It is the phase difference between the beam rotation phase and the accelerating electric field phase.

[0071] The definite integral of the sine function from 0 to 180° represents the total energy of the accelerated particles if all particles are accelerated during the half-cycle of acceleration. The definite integral shows that if a phase difference exists... ,exist Particles within a 180° phase width are not accelerated, deviate from their trajectory, and cannot be measured by the radial target. The definite integral value represents the total energy of the actually accelerated particles. The ratio of the two energies is the ratio of particle energies before and after the phase slip, which corresponds to the beam intensity ratio.

[0072] The sine of the phase difference Substituting these values ​​into the relationship between beam intensity ratio and phase difference, we obtain the sliding phase sine value, leading to the following relationship:

[0073] , It is the beam intensity ratio. This is the value of the sliding phase sine.

[0074] Thus, the value of the sliding phase sine was obtained.

[0075] Step S004: Record the current increase when the beam intensity reaches the upper limit of the beam intensity; calculate the beam slip based on the slip sine value and the current increase value to complete the beam slip measurement.

[0076] The superconducting coil current is gradually increased in small increments until the beam intensity measured on the radial target equals the upper limit of the beam intensity. The amount of increase in the superconducting coil current at this point is recorded. The superconducting coil current is gradually decreased in small increments until the beam current intensity measured on the radial target equals the upper limit of the beam current intensity. The increase in the superconducting coil current at this point is recorded. .

[0077] The beam slippage is calculated using the slippage sine value and the current increase of the two superconducting coils, based on the slippage measurement formula. The expression is:

[0078] , It is the size of the beam slip phase. It is the inverse function of the sine function. The value is the sine of the sliding phase. and This represents the increase in current for the two superconducting coils.

[0079] It should be noted that existing methods for calculating the magnitude of the slip phase do not include a slip phase sine term, i.e., they do not. This is because existing methods for calculating the magnitude of the beam slip phase set the beam intensity ratio to... The result is obtained by substituting one-half of the value into the calculation of the sliding phase sine. Therefore, the slip phase sinusoidal value term does not appear in its calculation method; the calculation formula for the magnitude of the slip phase of the beam is a publicly available technology in the field of plasma technology.

[0080] This completes the beam slip measurement of the medical cyclotron. Because this embodiment extracted interference noise from the beam intensity signal, and adjusted the superconducting coil current control conditions without affecting the final results, it reduced the frequency of superconducting coil current adjustments, avoiding the resulting decrease in accelerator stability and thus improving the accuracy of the beam slip measurement results.

[0081] Based on the same inventive concept as the above method, this embodiment of the invention also provides a medical cyclotron beam sliding phase measurement 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 one of the above-described medical cyclotron beam sliding phase measurement methods.

[0082] It should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

[0083] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A method for measuring the sliding phase of a beam in a medical cyclotron accelerator, characterized in that, The method includes the following steps: The beam intensity on the radial target at each moment is collected, and the vector formed by all beam intensities is recorded as the target quantity; The target quantity is divided into two parts, denoted as the front target quantity and the rear target quantity. The rear target quantity is symmetrically processed to obtain the symmetrical target quantity. The interference source sequence is determined based on the difference in beam intensity at the same position of the front and rear target quantities. The interference intensity in the acceleration region is obtained by analyzing the difference in the mean beam intensity of the front and rear target quantities. The interference source intensity sequence is determined by the difference between the interference source sequence and the interference intensity in the acceleration region. The interference source intensity sequence is processed using the 3 sigma principle to obtain the interference source fluctuation intensity. The upper limit of the beam intensity is determined by multiplying the interference source fluctuation intensity by the preset intensity. The average beam intensity of the target quantity at all times is calculated as the beam intensity of the target quantity. The ratio of the upper limit of the beam intensity to the beam intensity of the target quantity is denoted as the beam intensity ratio. The relationship between the beam intensity ratio and the phase difference is obtained by analyzing the phase width of the bundle: , 1 is the beam intensity ratio, and 2 is the definite integral of the sine function from 0 to 180°. It is the phase difference between the beam rotation phase and the accelerating electric field phase; substituting this relationship into the sine formula for the phase difference yields the sliding phase sine value, specifically: , It is the beam intensity ratio. The value is the sine value of the sliding phase; When the superconducting coil current is reduced, the increase in current when the beam current intensity reaches its upper limit is recorded, denoted as . When increasing the superconducting coil current, record the increase in current when the beam current intensity reaches its upper limit, denoted as ; ; The expression for beam slip phase: , It is the size of the beam slip phase. It is the inverse function of the sine function. The value is the sine of the sliding phase. and This represents the increase in current for the two superconducting coils.

2. The method for measuring beam slip phase in a medical cyclotron accelerator as described in claim 1, characterized in that, The method of dividing the target quantity into two parts, denoted as the front target quantity and the back target quantity, and symmetrically processing the back target quantity to obtain the symmetrical target quantity is as follows: The target quantity is evenly divided in the middle, with the front part being the front target quantity and the back part being the back target quantity; the back target quantity is then processed to obtain a symmetrical target quantity.

3. The method for measuring beam slip phase in a medical cyclotron as described in claim 1, characterized in that, The method for determining the interference source sequence based on the beam intensity difference at the same position between the front and rear target quantities is as follows: The absolute value of the difference between the beam intensity at the same position in the front target quantity and the symmetrical target quantity and the constant 2 are used as the element value; the sequence of element values ​​arranged in the same position order is used as the interference source sequence.

4. The method for measuring beam slip phase in a medical cyclotron as described in claim 1, characterized in that, The method of analyzing the difference in the average beam intensity between the front and rear target quantities to obtain the interference intensity in the acceleration region, and determining the interference source intensity sequence by the difference between the interference source sequence and the interference intensity in the acceleration region, is as follows: Let the ratio of the difference between the mean of the front target element and the mean of the rear target element to the constant 2 be taken as the interference intensity in the acceleration zone. The sequence obtained by subtracting the value of each element in the interference source sequence from the interference intensity in the acceleration region is used as the interference source intensity sequence.

5. The method for measuring beam slip phase in a medical cyclotron accelerator as described in claim 1, characterized in that, The method for processing the interference source intensity sequence using the 3 sigma principle to obtain the interference source fluctuation intensity is as follows: Calculate the mean and standard deviation of the sequence values ​​in the interference source intensity sequence, and let the sum of the mean and three times the standard deviation be taken as the interference source fluctuation intensity.

6. A medical cyclotron beam sliding phase measurement 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, it implements the steps of the medical cyclotron beam sliding phase measurement method as described in any one of claims 1-5.

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