A method for detecting magnetic field distribution of medical cyclotron magnets

Abstract

The present application relates to the field of magnetic field distribution detection technology, and specifically to a magnetic field distribution detection method for medical cyclotron magnets. The method comprises: dividing the medical cyclotron magnet to be detected into magnetic field regions; collecting the magnetic field strength at each moment in each magnetic field region, and dividing all magnetic field regions into categories; determining the magnetic field current disturbance value of any magnetic field region at the current moment; obtaining the coil current disturbance degree of any magnetic field region at the current moment; combining the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field region to determine the measurement error of the magnetic field strength measured in each magnetic field region, and judging and screening the magnetic field strength data of each magnetic field region. The present application improves the accuracy of magnetic field distribution detection of medical cyclotron magnets.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic field distribution detection, and in particular to a method for detecting magnetic field distribution of a medical cyclotron magnet. Background Art

[0002] Medical cyclotrons are crucial equipment for producing radiopharmaceuticals used in PET / CT scans, and ensuring their proper operation is crucial. The uniformity and stability of the magnetic field in medical cyclotrons directly impact particle acceleration efficiency and focusing. Magnetic field measurement can promptly detect and correct deviations and fluctuations in the magnetic field, such as those caused by surface defects on the magnetic poles and external interference. This ensures stable and efficient accelerator operation, improving particle acceleration efficiency and beam quality. Therefore, high-precision magnetic field measurement is crucial.

[0003] Existing technologies for detecting magnetic field distribution mainly use Hall probes to scan the magnetic field, move the probe to the required test position of various magnets, and obtain the magnetic field distribution in any space. However, traditional detection methods often focus on judging the magnetic field impact caused by defects in the magnet itself, and easily ignore the impact of internal and external currents of the magnet on monitoring. If the measured magnetic field of the electromagnet is greatly affected by the current, it will cause a large deviation during the magnetic field uniformity test, affecting the accuracy of magnetic field detection. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a method for detecting the magnetic field distribution of a medical cyclotron magnet to solve the existing problems.

[0005] The present invention provides a method for detecting the magnetic field distribution of a medical cyclotron magnet using the following technical solutions:

[0006] One embodiment of the present application provides a method for detecting magnetic field distribution of a medical cyclotron magnet, the method comprising the following steps:

[0007] The medical cyclotron magnet to be detected is divided into different magnetic field regions; the magnetic field strength at each time in each magnetic field region is collected, and the magnetic field strength at all times before the current time in each magnetic field region is combined into a magnetic field strength sequence;

[0008] The fluctuation frequency of each magnetic field region is determined by using the proportion of the peak value in the magnetic field intensity sequence of each magnetic field region; all magnetic field regions are divided into categories based on the similarity of the magnetic field intensity sequences between any two magnetic field regions;

[0009] Determine the magnetic field current disturbance value of any magnetic field region at a current moment based on the number of divided categories and the measured distances between all magnetic field regions in the category to which any magnetic field region belongs, in combination with the difference in the fluctuation frequency between any magnetic field region and all magnetic field regions remaining except for all magnetic field regions in the category to which any magnetic field region belongs, and the difference in the peak distribution between magnetic field intensity sequences;

[0010] Analyze the difference in trend intensity of magnetic field strength between all magnetic field regions in the radial direction of any magnetic field region at the current moment and all magnetic field regions remaining in the radial direction except for the any magnetic field region, and determine the coil current disturbance degree of the any magnetic field region at the current moment by combining the time difference between peaks of the same position in the magnetic field strength sequence between the any magnetic field region and the remaining magnetic field regions;

[0011] The magnetic field current disturbance value and the coil current disturbance degree of each magnetic field region are combined to determine the measurement error of the magnetic field strength measured in each magnetic field region, and the magnetic field strength data of each magnetic field region are judged and screened.

[0012] In one embodiment, the fluctuation frequency is the ratio of the total number of peaks in the magnetic field intensity sequence of each magnetic field region to the total number of sampling moments.

[0013] In one embodiment, dividing all magnetic field regions into categories includes:

[0014] The two magnetic field regions whose similarity is greater than or equal to a preset threshold are regarded as magnetic field regions of the same category.

[0015] In one embodiment, determining the magnetic field current disturbance value of any magnetic field region at the current moment includes:

[0016] Calculating the mean of the measured distances between all two arbitrary magnetic field regions in the category to which any one of the magnetic field regions belongs, and calculating the product of the mean and the number of the divided categories;

[0017] Recording a difference in the fluctuation frequency between the any magnetic field region and all remaining magnetic field regions, excluding all magnetic field regions in the category to which the any magnetic field region belongs, as a first difference;

[0018] Calculating an average value of all peak values ​​in a magnetic field intensity sequence of each magnetic field region, and recording a difference between the average values ​​of the any magnetic field region and all magnetic field regions in the category to which the any magnetic field region belongs as a second difference;

[0019] The first difference and the second difference are integrated and combined with the product to determine the magnetic field current disturbance value.

[0020] In one embodiment, the magnetic field current disturbance value is positively correlated with the fusion result and negatively correlated with the product.

[0021] In one embodiment, further determining the magnetic field current disturbance value includes:

[0022] The sum of the first difference and the second difference is calculated, and the cumulative sum of the sum of any one magnetic field region and all remaining magnetic field regions is calculated, and the magnetic field current disturbance value is the ratio of the cumulative sum to the product.

[0023] In one embodiment, determining the coil current disturbance degree of any magnetic field region at the current moment includes:

[0024] For any magnetic field region, obtain the radial direction from the center of the magnet to the magnetic field region and extend to the edge of the magnet, and form the magnetic field strength of all magnetic field regions at the current moment in the radial direction into a magnetic field radial sequence , the radial sequence of the magnetic field The sequence after removing the magnetic field intensity of any magnetic field region is recorded as the magnetic field radial sequence ;

[0025] Calculate the radial sequence of the magnetic field Radial sequence with magnetic field The difference in the trend strength is recorded as the third difference. The coil current disturbance degree is positively correlated with the third difference and negatively correlated with the time difference.

[0026] In one embodiment, the coil current disturbance degree is expressed as:

[0027] Where, is the coil current disturbance degree of the i-th magnetic field region at the current moment, is the radial sequence of the magnetic field in the i-th magnetic field region at the current moment The trend strength, is the radial sequence of the magnetic field in the i-th magnetic field region at the current moment The trend strength, is the corresponding moment of the kth peak in the magnetic field intensity sequence of the i-th magnetic field region at the current moment, is the time corresponding to the kth peak in the magnetic field strength sequence of the nth magnetic field region at the current moment, N is the number of magnetic field regions divided by the medical cyclotron magnet, is the number of peaks in the magnetic field intensity sequence of the i-th magnetic field region at the current moment, The default value is greater than 0.

[0028] In one embodiment, the measurement error is a normalized value of the product of the magnetic field current disturbance value and the coil current disturbance degree.

[0029] In one embodiment, the judging and screening of the magnetic field strength data of each magnetic field region includes:

[0030] Obtain a segmentation threshold of the measurement error of all current magnetic field regions. If the measurement error of any magnetic field region is greater than or equal to the segmentation threshold, determine that there is a deviation in the magnetic field strength measurement of any magnetic field region, and eliminate the magnetic field strength. Otherwise, determine that the magnetic field strength measurement of any magnetic field region is accurate, and retain the magnetic field strength.

[0031] This application has at least the following beneficial effects:

[0032] The present application is aimed at the medical cyclotron magnet to be detected, and divides it into various magnetic field regions; collects the magnetic field strength at each moment in each magnetic field region, and composes the magnetic field strength of each magnetic field region at all moments before the current moment into a magnetic field strength sequence; improves the ability to capture the dynamic evolution of the local magnetic field, and enhances the early identification ability of abnormal magnetic field regions; based on the similarity of the magnetic field strength sequences between any two magnetic field regions, all magnetic field regions are divided into categories; optimizes the spatial correlation modeling of the magnetic field distribution, and avoids the isolated analysis ignoring the magnetic field cooperative distortion phenomenon; further, determines the magnetic field current disturbance value of each magnetic field region at the current moment, improves the current disturbance tracing accuracy, and quantifies the magnetic field strength disturbance. The current interference degree obtained is improved, and the accuracy and reliability of the magnetic field strength measurement precision analysis are improved; the coil current disturbance degree of each magnetic field area at the current moment is determined, and the precise positioning of the radial magnetic field imbalance is realized, and the coupling analysis capability of the magnetic field strength in the time domain and the space domain is enhanced, which reflects the degree of interference of the magnetic field strength by the coil current; the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field area are combined to determine the measurement error of the magnetic field strength measured in each magnetic field area, and the magnetic field strength data of each magnetic field area are judged and screened, thereby improving the abnormal identification capability of the magnetic field strength of each magnetic field area, improving the credibility of the magnetic field strength measurement, and improving the accuracy of the magnetic field distribution detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1A flowchart of the steps of a method for detecting the magnetic field distribution of a medical cyclotron magnet provided in this application;

[0035] Figure 2 Flowchart for determining the measurement error of the magnetic field strength measured in the magnetic field area. DETAILED DESCRIPTION

[0036] To further illustrate the technical means and effectiveness of this application to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effectiveness of a method for detecting the magnetic field distribution of a medical cyclotron magnet proposed in this application. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0037] Unless defined otherwise, 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.

[0038] The following describes in detail a specific solution of a method for detecting the magnetic field distribution of a medical cyclotron magnet provided by the present application with reference to the accompanying drawings.

[0039] An embodiment of the present application provides a method for detecting the magnetic field distribution of a medical cyclotron magnet. Specifically, the following method for detecting the magnetic field distribution of a medical cyclotron magnet is provided. Figure 1 , the method comprises the following steps:

[0040] Step S001 : dividing the medical cyclotron magnet to be detected into magnetic field regions; collecting the magnetic field strength at each moment in each magnetic field region, and composing the magnetic field strength of each magnetic field region at all moments before the current moment into a magnetic field strength sequence.

[0041] For a medical cyclotron magnet to be detected, this embodiment divides the magnet into N magnetic field regions of equal size and uses a Hall probe to measure magnetic field strength data at the center point of each magnetic field region at intervals T. Finally, a magnetic field strength sequence of each magnetic field region of the medical cyclotron magnet at the current moment is constructed based on the sampling time sequence of the magnetic field strength. That is, the magnetic field strength of each magnetic field region at all times before the current moment is constructed into a magnetic field strength sequence of each magnetic field region in chronological order.

[0042] In this embodiment, N=64, T=0.5s. The implementer can adjust the values ​​of N and T according to the model and scale of the actual medical cyclotron, and this embodiment does not impose any limitation on this.

[0043] Step S002 , determining the fluctuation frequency of each magnetic field region using the proportion of the peak value in the magnetic field strength sequence of each magnetic field region; and dividing all magnetic field regions into categories based on the similarity of the magnetic field strength sequences between any two magnetic field regions.

[0044] Typically, medical cyclotrons are radial sector isochronous cyclotrons. Specifically, the magnetic field distribution of such cyclotrons varies in both radial and azimuthal directions, forming peaks and valleys. In the absence of interference, the magnetic field strength increases radially with increasing radius. The closer the magnetic field strength is to the center of the magnet, the more uniform the overall distribution.

[0045] In actual applications, during the casting process of the medical cyclotron magnet, defects such as shrinkage cavities and inclusions may appear inside the cover plate. These defects will affect the magnetic properties of the material and, in turn, the distribution of the magnetic field, resulting in a decrease in the uniformity of the magnetic field strength in the local area, a certain difference in magnetic field strength from the rest of the magnetic field area, and a non-uniform difference, which will change the overall distribution pattern of the magnetic field. Specifically, the distribution pattern of the magnetic field strength data collected in this embodiment changes from the center of the magnet to the outer edge of the magnet, the correlation between the magnetic field strength data and the location of the area in which it is located decreases, and there are some magnetic field areas with large differences in magnetic field strength from the rest of the magnetic field area, and the distribution is relatively discrete.

[0046] During cyclotron operation, current changes in the radio frequency system and beam extraction system can also cause disturbances in the cyclotron's magnetic field, similarly altering the overall magnetic field distribution. However, this type of interference is more concentrated, and because the source of the interference is consistent, the degree and frequency of magnetic field strength disturbances are similar. For example, the area affected by the beam extraction system is typically closer to the cyclotron's ion exit. Specifically, the frequency of magnetic field intensity fluctuations in a single magnetic field region differs significantly from that in more distant regions, but is similar to that in surrounding regions. Magnetic field regions with similar magnetic field intensity fluctuations are more densely distributed.

[0047] Based on the above analysis, for each magnetic field region at the current moment, this embodiment uses a peak search algorithm to obtain each peak value in the magnetic field strength sequence and its corresponding time, and takes the ratio of the total number of peak values ​​in the magnetic field strength sequence of each magnetic field region to the total number of sampling times as the fluctuation frequency of each magnetic field region at the current moment.

[0048] Furthermore, the similarity of the magnetic field intensity sequences between any two magnetic field regions among the N magnetic field regions divided by the medical cyclotron magnet at the current moment is calculated. The greater the similarity, the more similar the magnetic field intensity distributions of the corresponding two magnetic field regions are. Therefore, this embodiment presets a threshold Q, and regards two magnetic field regions with a similarity greater than or equal to the threshold Q as magnetic field regions of the same category. Based on this, the N magnetic field regions can be divided into multiple categories.

[0049] It should be noted that if the similarity between a magnetic field region and all remaining magnetic field regions is less than a threshold value Q, the magnetic field region is treated as a separate category; in this embodiment, the similarity is calculated using cosine similarity, and the implementer can choose other existing feasible similarity calculation methods, such as the Pearson correlation coefficient; in this embodiment, the threshold value Q is set to 0.97, and the implementer can set it according to actual conditions, and this embodiment does not impose any restrictions on this.

[0050] Step S003, based on the number of divided categories and the measured distance between all magnetic field regions in the category to which any magnetic field region belongs, combined with the difference in the fluctuation frequency between any magnetic field region and all magnetic field regions remaining in the category to which it belongs, and the difference in peak distribution between magnetic field intensity sequences, determine the magnetic field current disturbance value of any magnetic field region at the current moment.

[0051] Based on the above analysis, this embodiment calculates the magnetic field current disturbance value of each magnetic field region at the current moment, specifically:

[0052] Calculating the mean of the measured distances between all two magnetic field regions in the category to which any magnetic field region belongs, and calculating the product of the mean and the number of the divided categories;

[0053] Recording a difference in the fluctuation frequency between the any magnetic field region and all remaining magnetic field regions, excluding all magnetic field regions in the category to which the any magnetic field region belongs, as a first difference;

[0054] Calculating an average value of all peak values ​​in a magnetic field intensity sequence of each magnetic field region, and recording a difference between the average values ​​of the any magnetic field region and all magnetic field regions in the category to which the any magnetic field region belongs as a second difference;

[0055] The first difference and the second difference are integrated and combined with the product to determine the magnetic field current disturbance value.

[0056] It should be noted that the difference represents the degree of difference between two variables, which can be calculated by the absolute value of the difference, the square of the difference, the ratio, etc., and this embodiment does not limit this; fusion represents the combination of multiple variables, which can be calculated by addition, multiplication, or a mixture of addition and multiplication.

[0057] The calculation method of the magnetic field current disturbance value in this embodiment is:

[0058] Where, is the magnetic field current disturbance value of the i-th magnetic field region at the current moment, The number of categories assigned to all magnetic field regions of medical cyclotron magnets, is the mean of the measured distances between all two magnetic field regions in the category to which the i-th magnetic field region belongs at the current moment, are the fluctuation frequencies of the i-th and j-th magnetic field regions, are the mean values ​​of all peak values ​​in the magnetic field intensity sequence of the i-th and j-th magnetic field regions, respectively, and J is the number of all remaining magnetic field regions except for all magnetic field regions of the category to which the i-th magnetic field region belongs. Recorded as the first difference, Recorded as the second difference.

[0059] It should be noted that the metric distance described in this embodiment is calculated using Euclidean distance. The implementer may choose other feasible metric distance calculation methods. The Euclidean distance between magnetic field regions is calculated by obtaining the center points of all magnetic field regions and calculating the Euclidean distance between the center points of two magnetic field regions as the Euclidean distance between the magnetic field regions. When the i-th magnetic field region belongs to a category that contains only the i-th magnetic field region, let .

[0060] It should be understood that the smaller the Euclidean distance between all magnetic field regions of the category to which the i-th magnetic field region belongs, the greater the difference in fluctuation frequency and peak mean value from the magnetic field regions in other categories, and the fewer categories after the overall magnetic field region is classified, the more likely the magnetic field strength measured in the i-th magnetic field region is to be interfered with by the current, and the lower the measurement accuracy.

[0061] Step S004: Analyze the difference in trend intensity between the magnetic field strength of all magnetic field regions in the radial direction of any magnetic field region at the current moment and all magnetic field regions remaining in the radial direction except any magnetic field region, and determine the coil current disturbance degree of any magnetic field region at the current moment by combining the time difference between the peak values ​​of the same position in the magnetic field strength sequence of any magnetic field region and the remaining magnetic field regions.

[0062] During the operation of a medical cyclotron accelerator, the magnetic field is mainly generated by the main coil of the accelerator. The stability of its current directly affects the overall uniformity and strength of the magnetic field. When the current of the main coil becomes unstable or fluctuates, it will cause changes in the magnetic field strength. Specifically, the overall magnetic field strength will be subject to relatively similar interference. If a single magnetic field area is affected by defects in the magnet itself, the magnetic field current interference value will also be large, and it is easy to judge the magnetic field area as an area interfered with by current, thereby misjudging the actual situation of the magnetic field area. Therefore, the magnetic field strength of the magnetic field area is further analyzed.

[0063] When the magnetic field is affected by the unstable fluctuation of the current in the main coil, the entire magnetic field will be disturbed accordingly, so that all magnetic field areas will be subject to similar interference changes, and the time when the interference occurs is also similar. Compared with the area with magnetic defects, the magnetic field strength in the area affected by the main coil current will change as a whole, but because the degree of influence is similar, the law of magnetic field distribution is less affected, that is, the magnetic field strength increases in the radial direction with the increase of radius. On the contrary, the area with magnetic defects has a certain influence on the magnetic field itself, so the magnetic field distribution law in the radial direction is greatly affected.

[0064] In order to characterize the distribution law of magnetic field intensity in the magnet, for a single magnetic field region, take the i-th magnetic field region as an example, from the center of the magnet to the direction of the i-th magnetic field region, connect the center of the magnet with the center of the i-th magnetic field region, and extend the connecting line to the edge of the magnet, which is recorded as the radial direction of the i-th magnetic field region. The magnetic field intensity of all magnetic field regions in the radial direction of the i-th magnetic field region at the current moment is arranged in the order from near to far from the center point of the magnet to form a magnetic field radial sequence. , further, the magnetic field radial sequence After removing the magnetic field intensity data of the i-th magnetic field region, the sequence is reconstructed and recorded as the magnetic field radial sequence .

[0065] In combination with the above analysis, this embodiment calculates the coil current disturbance degree of each magnetic field region at the current moment. The specific expression is:

[0066] Where, is the coil current disturbance degree of the i-th magnetic field region at the current moment, is the radial sequence of the magnetic field in the i-th magnetic field region at the current moment The trend strength, is the radial sequence of the magnetic field in the i-th magnetic field region at the current moment The trend strength, is the corresponding moment of the kth peak in the magnetic field intensity sequence of the i-th magnetic field region at the current moment, is the time corresponding to the kth peak in the magnetic field strength sequence of the nth magnetic field region at the current moment, N is the number of magnetic field regions divided by the medical cyclotron magnet, is the number of peaks in the magnetic field intensity sequence of the i-th magnetic field region at the current moment, To preset a value greater than 0 to avoid the denominator being 0, in this embodiment , the implementer can set it according to the actual situation, and this embodiment does not limit it. This is recorded as the third difference. In this embodiment, the radial sequence of the magnetic field is The trend strength and radial sequence of magnetic field The trend strength is obtained by using the calculation method of the STL (Seasonal and Trend decomposition using Loess) decomposition algorithm. The STL decomposition algorithm is an existing well-known technology, and the specific process is not described in detail.

[0067] It should be understood that when the radial sequence of the magnetic field in the i-th magnetic field region is The stronger the trend, the stronger the radial sequence of the magnetic field. Radial sequence with magnetic field The greater the trend intensity difference, and the closer the sampling time of the peak in the magnetic field intensity sequence of the i-th magnetic field region is to that of the other magnetic field regions, the more likely the magnetic field intensity data collected in the i-th magnetic field region is to be affected by the unstable fluctuation of the coil current, and the lower the measurement accuracy.

[0068] Step S005 , combining the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field region, determining the measurement error of the magnetic field strength measured in each magnetic field region, and judging and screening the magnetic field strength data of each magnetic field region.

[0069] Furthermore, this embodiment combines the magnetic field current disturbance value of each magnetic field region with the coil current disturbance degree to determine the measurement error of the magnetic field strength measured in each magnetic field region, and characterizes the possibility of error in the measured magnetic field strength value of a single magnetic field region. The expression is:

[0070] Where, is the measurement error of the magnetic field strength measured in the i-th magnetic field region at the current moment, is the magnetic field current disturbance value of the i-th magnetic field region at the current moment, is the coil current disturbance degree of the i-th magnetic field region at the current moment, norm() is the normalization function. The flow chart for determining the measurement error of the magnetic field strength measured in the magnetic field region is as follows: Figure 2 shown.

[0071] The higher the degree of interference of the magnetic field current and the coil current on the magnetic field strength data measured in the i-th magnetic field region, the greater the possibility of deviation in the magnetic field strength data, and the less likely it is that the data should be used to judge the actual magnetic field conditions of the medical cyclotron.

[0072] Through the above method, the measurement errors of all current magnetic field regions can be calculated. All measurement errors are used as input, and the segmentation threshold of the measurement error is obtained by cross-validation. When the measurement error of a magnetic field region is greater than or equal to the segmentation threshold, it means that the measurement value of the magnetic field region is more likely to be interfered by the current inside and outside the cyclotron, so the measurement value has a large deviation. Otherwise, the measurement value of the magnetic field region is judged to be accurate, which can be used to judge the uniformity of the magnetic field distribution.

[0073] Based on this, the measurement error of each magnetic field area can be judged each time the magnetic field strength is measured. When the measurement error of a certain magnetic field area is greater than or equal to the segmentation threshold, the magnetic field strength data of the magnetic field area is eliminated. After resetting the measurement conditions, the magnetic field strength measurement is performed again until the measurement error of all magnetic field areas of the medical cyclotron magnet is less than the segmentation threshold, thereby realizing the magnetic field distribution detection of the medical cyclotron magnet.

[0074] It should be noted that the order in which the embodiments of the present application are presented is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. Furthermore, the foregoing descriptions of specific embodiments of this specification are provided. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential sequence shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0075] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0076] The above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them. Modifications to the technical solutions described in the aforementioned embodiments, or equivalent replacements of some of the technical features therein, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for detecting the magnetic field distribution of a medical cyclotron magnet, characterized in that: The method comprises the following steps: The medical cyclotron magnet to be detected is divided into different magnetic field regions; the magnetic field strength at each time in each magnetic field region is collected, and the magnetic field strength at all times before the current time in each magnetic field region is combined into a magnetic field strength sequence; The fluctuation frequency of each magnetic field region is determined by using the proportion of the peak value in the magnetic field intensity sequence of each magnetic field region; all magnetic field regions are divided into categories based on the similarity of the magnetic field intensity sequences between any two magnetic field regions; Calculate the mean of the metric distances between all arbitrary two magnetic field regions in the category to which any magnetic field region belongs, and calculate the product of the mean and the number of divided categories; record the difference in the fluctuation frequency between any magnetic field region and each remaining magnetic field region except all magnetic field regions in the category to which any magnetic field region belongs as a first difference; calculate the average value of all peak values ​​in the magnetic field intensity sequence of each magnetic field region, and record the difference in the average value between any magnetic field region and each remaining magnetic field region except all magnetic field regions in the category to which any magnetic field region belongs as a second difference; fuse the first difference and the second difference, and combine the product to determine the magnetic field current disturbance value of any magnetic field region at the current moment; Analyze the difference in trend intensity of magnetic field strength between all magnetic field regions in the radial direction of any magnetic field region at the current moment and all magnetic field regions remaining in the radial direction except for the any magnetic field region, and determine the coil current disturbance degree of the any magnetic field region at the current moment by combining the time difference between peaks of the same position in the magnetic field strength sequence between the any magnetic field region and the remaining magnetic field regions; Determine the measurement error of the magnetic field strength measured in each magnetic field region by combining the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field region, and perform judgment and screening on the magnetic field strength data of each magnetic field region; For any magnetic field region, obtain the radial direction from the center of the magnet to the magnetic field region and extend to the edge of the magnet, and form the magnetic field strength of all magnetic field regions at the current moment in the radial direction into a magnetic field radial sequence , the magnetic field radial sequence The sequence after removing the magnetic field intensity of any magnetic field region is recorded as the magnetic field radial sequence ; Calculate the radial sequence of the magnetic field Radial sequence with magnetic field The difference in the trend strength is recorded as the third difference. The coil current disturbance degree is positively correlated with the third difference and negatively correlated with the time difference.

2. A method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, characterized in that: The fluctuation frequency is the ratio of the total number of peaks in the magnetic field intensity sequence of each magnetic field region to the total number of sampling moments.

3. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein: All magnetic field areas are divided into categories, including: The two magnetic field regions whose similarity is greater than or equal to a preset threshold are regarded as magnetic field regions of the same category.

4. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein: The magnetic field current disturbance value is positively correlated with both the first difference and the second difference, and negatively correlated with the product.

5. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein: The further determination of the magnetic field current disturbance value includes: The sum of the first difference and the second difference is calculated, and the cumulative sum of the sum of any one magnetic field region and all remaining magnetic field regions is calculated, and the magnetic field current disturbance value is the ratio of the cumulative sum to the product.

6. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein: The expression of the coil current disturbance degree is: Where, is the coil current disturbance degree of the i-th magnetic field region at the current moment, is the radial sequence of the magnetic field in the i-th magnetic field region at the current moment The trend strength, is the radial sequence of the magnetic field in the i-th magnetic field region at the current moment The trend strength, is the corresponding moment of the kth peak in the magnetic field intensity sequence of the i-th magnetic field region at the current moment, is the time corresponding to the kth peak in the magnetic field strength sequence of the nth magnetic field region at the current moment, N is the number of magnetic field regions divided by the medical cyclotron magnet, is the number of peaks in the magnetic field intensity sequence of the i-th magnetic field region at the current moment, The default value is greater than 0.

7. The method for detecting the magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein: The measurement error is a normalized value of the product of the magnetic field current disturbance value and the coil current disturbance degree.

8. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein: The judging and screening of the magnetic field intensity data of each magnetic field region includes: Obtain a segmentation threshold of the measurement error of all current magnetic field regions. If the measurement error of any magnetic field region is greater than or equal to the segmentation threshold, determine that there is a deviation in the magnetic field strength measurement of any magnetic field region, and eliminate the magnetic field strength. Otherwise, determine that the magnetic field strength measurement of any magnetic field region is accurate, and retain the magnetic field strength.

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