CN120446830B - A method for detecting magnetic field distribution of medical cyclotron magnets - Google Patents

A method for detecting magnetic field distribution of medical cyclotron magnets

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CN120446830B
CN120446830B CN202510955534.8A CN202510955534A CN120446830B CN 120446830 B CN120446830 B CN 120446830B CN 202510955534 A CN202510955534 A CN 202510955534A CN 120446830 B CN120446830 B CN 120446830B
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magnetic field
difference
region
field region
sequence
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CN120446830A (en
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梁万胜
邵亚辉
刘静
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Shaanxi Zhengze Biotechnology Co ltd
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Shaanxi Zhengze Biotechnology Co ltd
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Abstract

The application relates to the technical field of magnetic field distribution detection, in particular to a magnetic field distribution detection method for a medical cyclotron magnet, which comprises the steps of equally dividing the medical cyclotron magnet to be detected into magnetic field areas; the method comprises the steps of collecting magnetic field intensity at each moment in each magnetic field area, dividing all the magnetic field areas into various categories, determining magnetic field current disturbance values of any magnetic field area at the current moment, obtaining coil current disturbance values of any magnetic field area at the current moment, determining measurement error degrees of magnetic field intensity measured by each magnetic field area by combining the magnetic field current disturbance values and the coil current disturbance values of each magnetic field area, and judging and screening magnetic field intensity data of each magnetic field area. The application improves the accuracy of magnetic field distribution detection of the medical cyclotron magnet.

Description

Magnetic field distribution detection method for medical cyclotron magnet
Technical Field
The application relates to the technical field of magnetic field distribution detection, in particular to a magnetic field distribution detection method for a medical cyclotron magnet.
Background
Medical cyclotrons are important devices for the production of radiopharmaceuticals in PET/CT examinations, it being vital to ensure their normal operation. In a medical cyclotron, the uniformity and stability of a magnetic field directly influence the acceleration efficiency and focusing degree of particles, the magnetic field measurement can timely find and correct deviation and fluctuation in the magnetic field, for example, the influence of magnetic pole surface defects and external interference on the magnetic field is ensured to stably and efficiently operate the accelerator, the acceleration efficiency and beam quality of the particles are improved, and therefore, the high-precision magnetic field measurement is very important.
In the prior art, a Hall probe is mainly used for scanning a magnetic field for detecting magnetic field distribution, so that the probe moves to a position required by various magnets to obtain any spatial magnetic field distribution, the traditional detection method is usually focused on judging magnetic field influence caused by defects of the magnets, influence of internal and external currents of the magnets on monitoring is easily ignored, and if the measured electromagnet magnetic field is greatly influenced by the currents, larger deviation is caused during magnetic field uniformity test, and magnetic field detection precision is influenced.
Disclosure of Invention
In order to solve the technical problems, the application provides a magnetic field distribution detection method for a medical cyclotron magnet, which aims at solving the existing problems.
The application discloses a magnetic field distribution detection method for a medical cyclotron magnet, which adopts the following technical scheme:
One embodiment of the application provides a magnetic field distribution detection method for a medical cyclotron magnet, which comprises the following steps:
the method comprises the steps of dividing a medical cyclotron magnet to be detected into magnetic field areas, collecting the magnetic field intensity of each moment in each magnetic field area, and forming a magnetic field intensity sequence by the magnetic field intensity of all moments before the current moment of each magnetic field area;
determining the fluctuation frequency of each magnetic field region by utilizing the proportion of the peak value in the magnetic field intensity sequence of each magnetic field region;
According to the number of the classified categories and the measurement distance between all magnetic field areas in the category to which any magnetic field area belongs, combining the difference of the fluctuation frequency between any magnetic field area and all magnetic field areas except the magnetic field areas in the category to which the magnetic field area belongs and the difference of peak distribution between magnetic field intensity sequences, determining the magnetic field current disturbed value of any magnetic field area at the current moment;
Analyzing the difference of the trend intensity of the magnetic field intensities of all the magnetic field areas in the radial direction of any magnetic field area at the current moment and all the magnetic field areas remained in the radial direction except any magnetic field area, and determining the coil current disturbance degree of any magnetic field area at the current moment by combining the time difference of the peak values of the same bit sequence in the magnetic field intensity sequences of any magnetic field area and all the other magnetic field areas;
And determining the measurement error degree of the magnetic field intensity measured by each magnetic field area by combining the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field area, and judging and screening the magnetic field intensity data of each magnetic field area.
In one embodiment, the fluctuation frequency is a ratio of a total number of peaks in the magnetic field intensity sequence of each magnetic field region to a total number of sampling moments.
In one embodiment, the dividing all magnetic field regions into categories includes:
And taking the two magnetic field areas with the similarity larger than or equal to a preset threshold value as the same type of magnetic field areas.
In one embodiment, the determining the magnetic field current disturbed value of the any magnetic field area at the current moment includes:
Calculating the average value of the measurement distances between any two magnetic field areas in the category to which any one magnetic field area belongs, and calculating the product of the average value and the number of the divided categories;
The difference of the fluctuation frequency of any magnetic field area and the rest magnetic field areas except all the magnetic field areas in the category of the any magnetic field area is recorded as a first difference;
Calculating the average value of all peak values in the magnetic field intensity sequence of each magnetic field area, and marking the difference between the average value of any magnetic field area and the rest magnetic field areas except all magnetic field areas in the category of the any magnetic field area as a second difference;
and fusing the first difference and the second difference, and combining the product to determine the magnetic field current disturbed value.
In one embodiment, the field current disturbance value is positively correlated with the result of the fusion and negatively correlated with the product.
In one embodiment, the further determination of the magnetic field current disturbed value comprises:
and calculating the sum value of the first difference and the second difference, and calculating the sum of the sum values of any magnetic field area and all the remaining magnetic field areas, wherein the magnetic field current disturbed value is the ratio of the sum value to the product.
In one embodiment, the determining the coil current disturbance degree of the any magnetic field area at the current moment includes:
For any magnetic field area, acquiring the radial direction that the center of the magnet points to the any magnetic field area and extends to the edge of the magnet, and forming the magnetic field intensity of all the magnetic field areas at the current moment in the radial direction into a magnetic field radial sequence Radial sequence of magnetic fieldsThe sequence after eliminating the magnetic field intensity of any magnetic field area is recorded as a magnetic field radial sequence;
Calculating a magnetic field radial sequenceRadial sequence with magnetic fieldThe difference in the trend intensity of (2) is noted as a third difference, and the coil current disturbance degree is positively correlated with the third difference and negatively correlated with the time difference.
In one embodiment, the coil current disturbance is expressed as:
In the formula (I), in the formula (II), For the coil current disturbance degree of the ith magnetic field area at the present moment,Radial sequence of magnetic fields for the ith magnetic field region at the current timeIs a function of the strength of the trend of (a),Radial sequence of magnetic fields for the ith magnetic field region at the current timeIs a function of the strength of the trend of (a),For the corresponding moment of the kth peak in the sequence of magnetic field strengths of the ith magnetic field region at the present moment,For the corresponding time of the kth peak value in the magnetic field intensity sequence of the nth magnetic field area at the current time, N is the number of magnetic field areas divided by the medical cyclotron magnet,For the number of peaks in the sequence of magnetic field strengths of the ith magnetic field region at the present moment,Is a preset value greater than 0.
In one embodiment, the measurement error degree is a normalized value of a product of the magnetic field current disturbance value and the coil current disturbance degree.
In one embodiment, the determining and screening the magnetic field intensity data of each magnetic field area includes:
Obtaining a segmentation threshold value of measurement error degrees of all current magnetic field areas, judging that the magnetic field intensity measurement of any magnetic field area has deviation if the measurement error degree of any magnetic field area is larger than or equal to the segmentation threshold value, eliminating the magnetic field intensity, otherwise, judging that the magnetic field intensity measurement of any magnetic field area is accurate, and reserving the magnetic field intensity.
The application has at least the following beneficial effects:
The method comprises the steps of dividing a medical cyclotron magnet to be detected into magnetic field areas, collecting magnetic field intensity of each moment in each magnetic field area, forming a magnetic field intensity sequence by the magnetic field intensity of each moment before the current moment, improving the capturing capability of dynamic evolution of a local magnetic field, enhancing the early recognition capability of abnormal magnetic field areas, dividing all the magnetic field areas into various categories based on the similarity of the magnetic field intensity sequence between any two magnetic field areas, optimizing the spatial correlation modeling of magnetic field distribution, avoiding the phenomenon that isolated analysis ignores magnetic field cooperative distortion, further determining the magnetic field current disturbance value of each magnetic field area at the current moment, improving the current disturbance tracing precision, quantifying the current disturbance degree of each magnetic field intensity, improving the accuracy and reliability of magnetic field intensity measurement precision analysis, determining the coil current disturbance degree of each magnetic field area at the current moment, realizing the accurate positioning of radial magnetic field unbalance, enhancing the coupling capability of magnetic field intensity time domain-space domain, reflecting the disturbance degree of the coil current of each magnetic field intensity, combining the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field area, determining the magnetic field intensity measurement error degree of each magnetic field intensity detection area, and improving the magnetic field intensity measurement precision of each magnetic field intensity measurement precision, and judging the magnetic field intensity.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions and advantages of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments of the application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of the steps of a method for detecting magnetic field distribution of a medical cyclotron magnet according to the present application;
Fig. 2 is a flowchart for determining the measurement error degree of the magnetic field intensity measured in the magnetic field region.
Detailed Description
In order to further describe the technical means and effects adopted by the present application to achieve the preset purposes, the following description refers to the specific implementation, structure, characteristics and effects of a magnetic field distribution detection method for a medical cyclotron magnet according to the present application with reference to the accompanying drawings and the preferred embodiments. In the following description, different "one embodiment" or "another embodiment" means that the embodiments are not necessarily the same. Furthermore, the particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.
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.
The following specifically describes a specific scheme of a magnetic field distribution detection method for a medical cyclotron magnet according to the present application with reference to the accompanying drawings.
The present application provides a magnetic field distribution detection method for a medical cyclotron magnet, and in particular, provides a magnetic field distribution detection method for a medical cyclotron magnet, referring to fig. 1, the method includes the following steps:
Step S001, equally dividing the medical cyclotron magnet to be detected into magnetic field areas, collecting the magnetic field intensity at each moment in each magnetic field area, and forming a magnetic field intensity sequence from the magnetic field intensity at all moments before the current moment of each magnetic field area.
For the medical cyclotron magnet to be detected, the embodiment divides the magnet into N magnetic field areas with equal size, measures magnetic field intensity data of the center point of each magnetic field area by utilizing a Hall probe at each interval time T, and finally constructs a magnetic field intensity sequence of each magnetic field area of the medical cyclotron magnet at the current moment according to the sampling moment sequence of the magnetic field intensity, namely, the magnetic field intensities of all the moments before the current moment of each magnetic field area form the magnetic field intensity sequence of each magnetic field area in time sequence.
In this embodiment, n=64 and t=0.5 s, and the practitioner can adjust the values of N and T according to the model scale of the actual medical cyclotron, which is not limited in this embodiment.
Step S002, determining the fluctuation frequency of each magnetic field area by utilizing the proportion of the peak value in the magnetic field intensity sequence of each magnetic field area, and dividing all the magnetic field areas into various categories based on the similarity of the magnetic field intensity sequences between any two magnetic field areas.
Typically, the medical cyclotron is a radial fan isochronous cyclotron, and in particular, the magnetic field distribution of such cyclotron varies in radial and azimuthal directions, forming "peaks" and "Gu Ou". Under the condition of no interference, the magnetic field intensity increases along the radial direction along with the increase of the radius, and the magnetic field intensity of the magnet area which is close to the center of the magnet is more close, so that the overall distribution is more uniform.
In practical application, defects such as shrinkage holes and inclusions can occur in the cover plate in the process of casting the magnet of the medical cyclotron, and the defects can influence the magnetic property of materials, further influence the distribution of a magnetic field, reduce the uniformity of the magnetic field intensity in a local area, generate certain magnetic field intensity difference in other magnetic field areas, and have uneven difference degrees, so that the overall distribution rule of the magnetic field is changed. The distribution rule of the magnetic field intensity data collected by the embodiment from the center of the magnet to the edge of the outer side of the magnet is changed, the correlation degree of the magnetic field intensity data and the position of the area where the magnetic field intensity data is located is reduced, the magnetic field intensity difference between a part of magnetic field area and other magnetic field areas is larger, and the distribution is more discrete.
In the operation process of the cyclotron, the current changes of the radio frequency system and the beam extraction system may also cause the magnetic field of the cyclotron to be disturbed, and the overall distribution rule of the magnetic field is also changed, but the scope of the disturbance is concentrated, and the extent and the frequency of the disturbance to the magnetic field intensity are similar because of the consistent disturbance sources, for example, the influence area of the beam extraction system is generally closer to the ion outlet of the cyclotron. The method is characterized in that the frequency of the fluctuation of the magnetic field intensity of a single magnetic field area is larger than that of the magnetic field area with a larger distance, but the frequency of the fluctuation of the magnetic field intensity of the single magnetic field area is similar to that of the surrounding magnetic field area, and the distribution of the magnetic field areas with similar magnetic field intensity variation is more dense.
Based on the analysis, for each magnetic field area at the current moment, the embodiment adopts a peak value searching algorithm to acquire each peak value in the magnetic field intensity sequence and the corresponding moment thereof, and takes the ratio of the total number of the peak values in the magnetic field intensity sequence of each magnetic field area to the total number of the sampling moments as the fluctuation frequency of each magnetic field area at the current moment.
Further, in the N magnetic field regions divided by the medical cyclotron magnet at the current moment, the greater the similarity of the magnetic field intensity sequences between any two magnetic field regions, the higher the similarity is, which indicates that the magnetic field intensity distribution approximation degree of the corresponding two magnetic field regions is higher, so the embodiment presets the threshold Q, and two magnetic field regions with the similarity equal to or greater than the threshold Q are used as the magnetic field regions of the same category, based on which the N magnetic field regions can be divided into a plurality of categories.
It should be noted that if the similarity between the magnetic field area and all the remaining magnetic field areas is smaller than the threshold Q, the magnetic field area is used as a class alone, the similarity in this embodiment is calculated by using cosine similarity, and an implementer may select other feasible similarity calculation methods, such as pearson correlation coefficient, etc., in this embodiment, the threshold Q is set to 0.97, and the implementer may set itself according to the actual situation, which is not limited in this embodiment.
Step S003, determining a magnetic field current disturbed value of any magnetic field region at the current moment according to the number of the divided categories and the measured distance between all the magnetic field regions in the category to which the any magnetic field region belongs, and combining the difference of the fluctuation frequency between the any magnetic field region and the rest magnetic field regions except for all the magnetic field regions in the category to which the any magnetic field region belongs and the difference of the peak distribution between the magnetic field intensity sequences.
Based on the above analysis, the present embodiment calculates the magnetic field current disturbance value of each magnetic field region at the present moment, specifically:
Calculating the average value of the measurement distances between any two magnetic field areas in the category to which any magnetic field area belongs, and calculating the product of the average value and the number of the divided categories;
The difference of the fluctuation frequency of any magnetic field area and the rest magnetic field areas except all the magnetic field areas in the category of the any magnetic field area is recorded as a first difference;
Calculating the average value of all peak values in the magnetic field intensity sequence of each magnetic field area, and marking the difference between the average value of any magnetic field area and the rest magnetic field areas except all magnetic field areas in the category of the any magnetic field area as a second difference;
and fusing the first difference and the second difference, and combining the product to determine the magnetic field current disturbed value.
It should be noted that, the difference represents the degree of difference between two variables, and may be calculated by means of absolute value of difference, square of difference, ratio, etc., which is not limited in this embodiment, and the fusion represents the combination of multiple variables, and may be calculated by means of addition, multiplication, addition-multiplication, mixing, etc.
The calculation method of the magnetic field current disturbed value in this embodiment is as follows:
In the formula (I), in the formula (II), The magnetic field current disturbance value of the ith magnetic field area at the current moment,The number of categories divided for all magnetic field areas of the medical cyclotron magnet,Is the average value of the measurement distances between any two magnetic field areas in the category to which the ith magnetic field area at the current moment belongs,The fluctuation frequencies of the ith and jth magnetic field regions respectively,The average value of all peaks in the magnetic field intensity sequences of the ith and jth magnetic field areas respectively, and J is the number of all magnetic field areas except all magnetic field areas of the category to which the ith magnetic field area belongs. Will beThe first difference is noted as a first difference,The second difference is noted.
It should be noted that, in this embodiment, the metric distance is calculated by using the euclidean distance, and an operator may select other available metric distance calculation modes by himself, where the euclidean distance calculation mode between magnetic field areas is to obtain center points of all magnetic field areas, and calculate the euclidean distance between the center points of two magnetic field areas as the euclidean distance between the magnetic field areas. When only the ith magnetic field area exists in the category to which the ith magnetic field area belongs, let
It should be understood that, when the euclidean distance between all magnetic field regions of the category to which the ith magnetic field region belongs is smaller, the fluctuation frequency and the peak mean value difference between the magnetic field regions in the rest categories are larger, and the categories of the whole magnetic field region after being classified are smaller, the more likely that the magnetic field intensity measured by the ith magnetic field region is interfered by current, and the lower the accuracy of measurement is.
Step S004, analyzing the difference of the trend intensity of the magnetic field intensity of all the magnetic field areas in the radial direction of any magnetic field area at the current moment and the magnetic field intensity of all the remaining magnetic field areas in the radial direction except any magnetic field area, and determining the coil current disturbance degree of any magnetic field area at the current moment by combining the time difference of the peak values of the same bit sequence in the magnetic field intensity sequences of any magnetic field area and all the remaining magnetic field areas.
In the operation process of the medical cyclotron, a magnetic field is mainly generated through a main coil of the accelerator, the stability of current of the magnetic field directly influences the uniformity and intensity of the whole magnetic field, when the current of the main coil is unstable or fluctuates, the magnetic field intensity is changed, the magnetic field intensity is more approximately disturbed, if a single magnetic field area is influenced by the defects of a magnet, the magnetic field current disturbance value is larger, and the magnetic field area is easily judged as the area interfered by the current, so that the real condition of the magnetic field area is misjudged, and the magnetic field intensity of the magnetic field area is further analyzed.
When the magnetic field is influenced by the unstable fluctuation of the current of the main coil, the whole magnetic field is correspondingly disturbed, so that all magnetic field areas are subjected to approximate disturbance change, the moment of occurrence of disturbance is approximate, and compared with the area with the magnetic defects, the magnetic field intensity of the area influenced by the current of the main coil is changed integrally, but the influence degree is approximate, so that the rule of magnetic field distribution is lower, namely the magnetic field intensity is increased along the radial direction along with the increase of the radius, and conversely, the area with the magnetic defects has a certain influence on the magnetic field due to the fact that the area with the magnetic defects has a certain influence on the magnetic field, so that the rule of magnetic field distribution in the radial direction is greatly influenced.
For representing the magnetic field intensity distribution rule in the magnet, taking the ith magnetic field area as an example, pointing the direction of the ith magnetic field area from the magnet center to the ith magnetic field area, connecting the magnet center with the center of the ith magnetic field area, extending a connecting line to the edge of the magnet, marking the radial direction of the ith magnetic field area, and forming a magnetic field radial sequence from the near to far from the magnet center point according to the magnetic field intensities of all the magnetic field areas in the radial direction of the ith magnetic field area at the current momentFurther, the magnetic fields are radially sequencedAfter the magnetic field intensity data of the ith magnetic field area is removed, reconstructing a sequence, and marking the sequence as a magnetic field radial sequence
In combination with the above analysis, the embodiment calculates the coil current disturbance degree of each magnetic field area at the current moment, and the specific expression is as follows:
In the formula (I), in the formula (II), For the coil current disturbance degree of the ith magnetic field area at the present moment,Radial sequence of magnetic fields for the ith magnetic field region at the current timeIs a function of the strength of the trend of (a),Radial sequence of magnetic fields for the ith magnetic field region at the current timeIs a function of the strength of the trend of (a),For the corresponding moment of the kth peak in the sequence of magnetic field strengths of the ith magnetic field region at the present moment,For the corresponding time of the kth peak value in the magnetic field intensity sequence of the nth magnetic field area at the current time, N is the number of magnetic field areas divided by the medical cyclotron magnet,For the number of peaks in the sequence of magnetic field strengths of the ith magnetic field region at the present moment,For values greater than 0, the denominator is avoided to be 0, in this embodimentThe implementation can be set by the implementation personnel according to the actual situation, and the embodiment is not limited to this. Will beThe third difference is noted. Radial sequence of magnetic fields in this embodimentTrend intensity and magnetic field radial sequence of (c)The trend intensity of (a) is obtained by adopting a calculation mode in STL (Seasonal and Trend decomposition using Loess) decomposition algorithm, wherein the STL decomposition algorithm is the prior known technology, and the specific process is not repeated.
It should be appreciated that when the field radial sequence of the ith field regionThe stronger the trend intensity of (c) and the radial sequence of magnetic fieldsRadial sequence with magnetic fieldThe greater the trend intensity difference and the closer the sampling time of the peak appears in the magnetic field intensity sequences of the ith magnetic field area and the rest magnetic field areas, the more likely the magnetic field intensity data acquired in the ith magnetic field area is affected by the unstable fluctuation of the coil current, and the lower the measured value accuracy is.
And S005, determining the measurement error degree of the magnetic field intensity measured by each magnetic field area by combining the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field area, and judging and screening the magnetic field intensity data of each magnetic field area.
Further, in this embodiment, the magnetic field current disturbance value and the coil current disturbance degree of each magnetic field region are fused, the measurement error degree of the magnetic field strength measured by each magnetic field region is determined, the possibility that the measured magnetic field strength value representing a single magnetic field region has an error is represented by the following expression:
In the formula (I), in the formula (II), The measurement error degree of the magnetic field intensity measured by the ith magnetic field area at the current moment,The magnetic field current disturbance value of the ith magnetic field area at the current moment,For the coil current disturbance degree of the ith magnetic field area at the current moment, norm () is a normalization function. A flow chart for determining the degree of measurement error of the magnetic field strength measured in the magnetic field region is shown in fig. 2.
When the magnetic field intensity data measured in the ith magnetic field area is interfered by the current of the magnetic field and the coil current is interfered to a higher degree, the possibility that the magnetic field intensity data has deviation is higher, and the magnetic field intensity data is not used for judging the actual magnetic field condition of the medical cyclotron.
By the method, the measurement error degrees of all current magnetic field areas can be calculated, all the measurement error degrees are used as input, the segmentation threshold value of the measurement error degrees is obtained by using a cross-validation mode, when the measurement error degrees of the magnetic field areas are larger than or equal to the segmentation threshold value, the measurement value of the magnetic field areas is more likely to be interfered by currents inside and outside the cyclotron, and therefore larger deviation exists in the measurement value, otherwise, the measurement value of the magnetic field areas is judged to be accurate, and the measurement value can be used for judging the distribution uniformity degree of the magnetic field.
Based on the method, the measurement error condition of each magnetic field area can be judged when the magnetic field intensity is measured each time, when the measurement error degree of a certain magnetic field area is larger than or equal to the segmentation threshold value, the magnetic field intensity data of the magnetic field area are removed, and after the measurement working condition is reset, the magnetic field intensity measurement is carried out again until the measurement error degree of all the magnetic field areas of the medical cyclotron magnet is smaller than the segmentation threshold value, so that the magnetic field distribution detection of the medical cyclotron magnet is realized.
It should be noted that the sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. And the foregoing description has been directed to specific embodiments of this specification. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
In this specification, each embodiment is described in a progressive manner, and the same or similar parts of each embodiment are referred to each other, and each embodiment mainly describes differences from other embodiments.
The embodiments described above are only for illustrating the technical solutions of the present application, but not for limiting the same, and the technical solutions described in the foregoing embodiments are modified or some of the technical features are replaced equivalently, so that the essence of the corresponding technical solutions does not deviate from the scope of the technical solutions of the embodiments of the present application, and all the technical solutions are included in the protection scope of the present application.

Claims (8)

1.一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,该方法包括以下步骤:1. A method for detecting the magnetic field distribution of a medical cyclotron magnet, characterized in that the method comprises the following steps: 针对待探测的医用回旋加速器磁铁,将其均分为各磁场区域;采集各磁场区域内各时刻的磁场强度,将各磁场区域当前时刻前所有时刻的磁场强度组成磁场强度序列;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; 利用各磁场区域的磁场强度序列中峰值的所占比例,确定各磁场区域的波动频率;基于任意两磁场区域之间磁场强度序列的相似性,将所有磁场区域划分为各类别;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; 计算任一磁场区域的所属类别中所有任意两磁场区域之间的度量距离的均值,计算所述均值与划分的类别数量的乘积;将除所述任一磁场区域的所属类别中所有磁场区域之外,所述任一磁场区域与剩余各磁场区域的波动频率的差异,记为第一差异;计算各磁场区域的磁场强度序列中所有峰值的平均值,将除所述任一磁场区域的所属类别中所有磁场区域之外,所述任一磁场区域与剩余各磁场区域的所述平均值的差异,记为第二差异;融合所述第一差异与所述第二差异,结合所述乘积,确定当前时刻所述任一磁场区域的磁场电流受扰值;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; 分析当前时刻所述任一磁场区域的径向方向上所有磁场区域与除所述任一磁场区域外其径向方向上剩余所有磁场区域的磁场强度的趋势性强度的差异,结合所述任一磁场区域与其余各磁场区域的磁场强度序列中相同位序的峰值的时间差异,确定当前时刻所述任一磁场区域的线圈电流受扰度;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; 结合各磁场区域的所述磁场电流受扰值与所述线圈电流受扰度,确定各磁场区域所测磁场强度的测量误差度,对各磁场区域的磁场强度数据进行判断筛选;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; 针对所述任一磁场区域,获取磁铁中心指向所述任一磁场区域并延长至磁铁边缘的径向方向,将径向方向上当前时刻所有磁场区域的磁场强度组成磁场径向序列,将磁场径向序列中剔除所述任一磁场区域的磁场强度后的序列,记为磁场径向序列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 ; 计算磁场径向序列与磁场径向序列的趋势性强度的差异,记为第三差异,所述线圈电流受扰度与所述第三差异成正相关,与所述时间差异成负相关。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.如权利要求1所述的一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,所述波动频率为各磁场区域的磁场强度序列中峰值的总个数与采样时刻的总个数的比值。2. A method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein 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.如权利要求1所述的一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,所述将所有磁场区域划分为各类别,包括:3. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein the step of dividing all magnetic field regions into categories comprises: 将所述相似性大于等于预设阈值的两磁场区域作为同类别的磁场区域。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.如权利要求1所述的一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,所述磁场电流受扰值与所述第一差异、所述第二差异均成正相关,与所述乘积成负相关。4. A 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.如权利要求1所述的一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,所述磁场电流受扰值的进一步确定包括:5. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1 , wherein further determining the magnetic field current disturbance value comprises: 计算所述第一差异与所述第二差异的和值,计算所述任一磁场区域与剩余所有磁场区域的所述和值的累加和,所述磁场电流受扰值为所述累加和与所述乘积的比值。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.如权利要求1所述的一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,所述线圈电流受扰度的表达式为:6. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein the coil current disturbance degree is expressed as: ;式中,为当前时刻第i个磁场区域的线圈电流受扰度,为当前时刻第i个磁场区域的磁场径向序列的趋势性强度,为当前时刻第i个磁场区域的磁场径向序列的趋势性强度,为当前时刻第i个磁场区域的磁场强度序列中第k个峰值的对应时刻,为当前时刻第n个磁场区域的磁场强度序列中第k个峰值的对应时刻,N为医用回旋加速器磁铁划分的磁场区域的数量,为当前时刻第i个磁场区域的磁场强度序列中峰值的数量,为预设大于0的数值。 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.如权利要求1所述的一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,所述测量误差度为所述磁场电流受扰值与所述线圈电流受扰度的乘积的归一化值。7. A 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. 8.如权利要求1所述的一种针对医用回旋加速器磁铁的磁场分布探测方法,其特征在于,所述对各磁场区域的磁场强度数据进行判断筛选,包括:8. The method for detecting magnetic field distribution of a medical cyclotron magnet according to claim 1, wherein the step of judging and screening the magnetic field intensity data of each magnetic field region comprises: 获取当前所有磁场区域的测量误差度的分割阈值,若所述任一磁场区域的测量误差度大于等于所述分割阈值,判定所述任一磁场区域的磁场强度测量存在偏差,将该磁场强度进行剔除,否则,判定所述任一磁场区域的磁场强度测量精准,将该磁场强度进行保留。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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