Medical cyclotron magnetic measurement system calibration method

Abstract

The invention relates to the technical field of cyclotron calibration, and provides a medical cyclotron magnetic measurement system calibration method comprising the following steps: collecting radiuses of all detection coils of a medical cyclotron, and magnetic induction intensity data and temperature data of all detection coils at different heights; obtaining a longitudinal magnetic induction intensity sequence and a transverse magnetic induction intensity sequence; obtaining an abnormal coefficient of the target detection coil, and determining a standard detection coil and a non-standard detection coil; constructing a temperature-magnetism relation point set, determining the weight of each point in the temperature-magnetism relation point set, and further determining a temperature-magnetism relation curve; and calibrating the magnetic induction intensity data of the non-standard detection coil at each height according to the temperature-magnetism relation curve to realize calibration of the magnetic measurement system of the medical cyclotron. The invention aims to solve the problems that the internal resistance of different detection coils in a detection coil panel is different and can be changed, so that the calibration result of a magnetic measurement system is deviated, and the performance of a medical cyclotron is poor.

Description

Technical Field

[0001] The invention relates to the technical field of cyclotron calibration, and in particular to a calibration method for a medical cyclotron magnetic measurement system. Background Art

[0002] A cyclotron is a device that uses magnetic and electric fields to make charged particles perform cyclotron motion, and repeatedly accelerates them through high-frequency electric fields during motion. In the field of modern medicine, medical cyclotrons can be used to accelerate charged particles to a high energy state for cancer radiotherapy. Superconducting cyclotrons provide magnetic fields through main magnets and superconducting coils at room temperature. The magnetic field will have a great influence on the final state of the particles. Therefore, in the process of using medical cyclotrons to accelerate charged particles, the magnetic field needs to be precisely controlled. Generally, the electromagnetic induction principle of the detection coil is used to measure and calibrate the magnetic field of the superconducting coil to reduce the error of the magnetic measurement system and the detection coil.

[0003] The prior art generally calibrates the magnetic measurement system according to the change in magnetic field strength of different detection coils in the detection coil disk. However, the resistance of different detection coils in the detection coil disk is different and will change. The different and changing internal resistance of the detection coil will affect the change in the magnetic field strength of the detection coil, resulting in deviations in the calibration results of the magnetic measurement system and affecting the performance of the medical cyclotron. Summary of the invention

[0004] The present invention provides a method for calibrating a magnetic measurement system of a medical cyclotron to solve the problem that the internal resistance of different detection coils in a detection coil disk is different and changes, which affects the change of the magnetic field strength of the detection coil, resulting in deviation in the calibration result of the magnetic measurement system and poor performance of the medical cyclotron. The technical solution adopted is as follows: An embodiment of the present invention provides a method for calibrating a medical cyclotron magnetic measurement system, the method comprising the following steps: Collect the radii of all different detection coils in the detection coil disk of the medical cyclotron, as well as the magnetic induction intensity data and temperature data of all detection coils in the detection coil disk at different heights, and obtain the longitudinal magnetic induction intensity sequence of the same detection coil and the transverse magnetic induction intensity sequence at the same height; Any detection coil in the detection coil disk is recorded as a target detection coil, an abnormal coefficient of the target detection coil is obtained, and a standard detection coil and a non-standard detection coil are determined according to the abnormal coefficients of all detection coils in the detection coil disk; According to the relationship between the difference in radius between the non-standard detection coil and the standard detection coil and the difference in magnetic induction data at the same height, and the relationship between the difference in temperature data between the non-standard detection coil and the standard detection coil at the same height and the difference in magnetic induction data at the same height, a second fitting curve at the same height is obtained; according to the difference between the magnetic induction data differences corresponding to any two different second fitting curves when the same radius difference is taken, a temperature-magnetic relationship point set is constructed; according to the two different second fitting curves corresponding to each point in the temperature-magnetic relationship point set and the difference between the temperature data of the non-standard detection coil at all heights corresponding to each point in the temperature-magnetic relationship point set, a weight of each point in the temperature-magnetic relationship point set is determined; according to the weight of each point in the temperature-magnetic relationship point set, the temperature data of the non-standard detection coil and the standard detection coil, and the magnetic induction data of the non-standard detection coil and the standard detection coil, a temperature-magnetic relationship curve is obtained; The magnetic induction intensity data of the non-standard detection coil at each height are calibrated according to the temperature-magnetism relationship curve to realize the calibration of the medical cyclotron magnetic measurement system.

[0005] Furthermore, the method of obtaining the longitudinal magnetic induction intensity sequence of the same detection coil and the transverse magnetic induction intensity sequence at the same height includes: Arrange all magnetic induction intensity data of the same detection coil in the detection coil disk in the order of the height of the magnetic induction intensity data collection from low to high, and obtain the longitudinal magnetic induction intensity sequence of the same detection coil; The magnetic induction intensity data of all detection coils collected at the same height are sorted in descending order of the radius of the detection coils to obtain a transverse magnetic induction intensity sequence at the same height.

[0006] Further, the specific method of obtaining the abnormal coefficient of the target detection coil includes: Taking the radius of all detection coils in the detection coil disk as the independent variable and the magnetic induction intensity data of each detection coil at the same height as the dependent variable, a polynomial curve fitting algorithm is used to obtain a first fitting curve at the same height; respectively calculating the curvature of the points corresponding to the radius of all detection coils in each first fitting curve, arranging the curvatures of all calculated points of the first fitting curve at the same height in the order from small to large according to the radius of the detection coil corresponding to the curvature, and obtaining the curvature sequence at the same height; Any detection coil in the detection coil disk is recorded as the target detection coil, and the number of non-positive numbers in the curvature corresponding to the target detection coil in all curvature sequences at the same height is recorded as the number of non-positive curvatures of the target detection coil; The variance of all data contained in the first-order difference sequence of the curvature sequence at the same height is recorded as the first difference variance at the same height; The difference values ​​calculated from the curvatures of the points corresponding to the radius of all target detection coils in the curvature difference sequence at the same height are deleted, and the variances of all the remaining difference values ​​in the curvature difference sequence at the same height are recorded as the second difference variance of the target detection coil at the same height; According to the number of non-positive curvatures of the detection coils, the first differential variance at the same height, the second differential variance at the same height, and the correlation between the longitudinal magnetic induction intensity sequences of all the detection coils, the abnormal coefficient of each detection coil in the detection coil disk is obtained.

[0007] Further, the abnormal coefficient of each detection coil in the detection coil disk is obtained according to the number of non-positive curvatures of the detection coil, the first differential variance at the same height, the second differential variance at the same height, and the correlation between the longitudinal magnetic induction intensity sequences of all the detection coils, including the specific method of: In the formula, Indicates the detection coil disk The anomaly coefficient of the detection coil; Indicates the number of detection coils in the disk The number of non-positive numbers contained in the first-order difference sequence of the longitudinal magnetic induction intensity sequence of the detection coils; Indicates the number of detection coils in the disk The number of non-positive curvatures of the detection coils; represents the mean of all first difference variances of the same height; Indicates the detection coil disk The mean of the variances of the second differences of all detection coils at the same height; represents the first parameter of the preset; Indicates the number of detection coils in the disk The average of the absolute values ​​of the correlation coefficients between the longitudinal magnetic induction intensity sequences of a detection coil and all other detection coils.

[0008] Furthermore, the specific method of determining the standard detection coil and the non-standard detection coil includes: The detection coil with the smallest abnormal coefficient is recorded as the standard detection coil, and the detection coil that is not the standard detection coil is recorded as the non-standard detection coil.

[0009] Furthermore, the specific method for obtaining the second fitting curve at the same height is: The difference in temperature data between the non-standard detection coil and the standard detection coil in the detection coil disk at the same height and the difference in radius between the non-standard detection coil and the standard detection coil in the detection coil disk are used as independent variables, and the difference in magnetic induction intensity data between the non-standard detection coil and the standard detection coil in the detection coil disk at the same height is used as the dependent variable. Multiple nonlinear regression analysis is used to obtain the second fitting curve at the same height.

[0010] Furthermore, the specific method of constructing the temperature-magnetic relationship point set is as follows: The function values ​​calculated by the second fitting curve at all heights are recorded as the first intensity difference, and the difference between the radius of the non-standard detection coil and the standard detection coil corresponding to the first intensity difference is recorded as the first radius difference of the first intensity difference; A plane rectangular coordinate system is established by taking the difference between the first intensity difference values ​​corresponding to every two identical first radius difference values ​​in any two different second fitting curves as the ordinate, and taking the difference between the temperature data of the detection coil corresponding to every two identical first radius difference values ​​in any two different second fitting curves as the abscissa, marking the points corresponding to every two identical first radius difference values ​​in the plane rectangular coordinate system, and recording the set consisting of all points in the plane rectangular coordinate system as the temperature-magnetic relationship point set.

[0011] Furthermore, the weight of each point in the temperature-magnetic relationship point set is obtained by: Calculate the goodness of fit of each second fitting curve; The calculation formula for the weight of the temperature-magnetic relationship point concentration point is: In the formula, Indicates the concentration of temperature-magnetic relationship points The weight of each point; Indicates the concentration of temperature-magnetic relationship points The minimum goodness of fit of two different second fitting curves corresponding to points; Indicates the preset second parameter; Indicates the concentration of temperature-magnetic relationship points The temperature standard deviation of the non-standard detection coil corresponding to each point.

[0012] Furthermore, the temperature-magnetic relationship curve is obtained by: The difference in temperature data between the non-standard detection coil and the standard detection coil is taken as the independent variable, the weight of the point is taken as the weight of the independent variable corresponding to the non-standard detection coil corresponding to the point, and the difference in magnetic induction intensity data between the non-standard detection coil and the standard detection coil is taken as the dependent variable. Weighted curve fitting is performed to obtain the temperature-magnetism relationship curve.

[0013] Furthermore, the magnetic induction intensity data of the non-standard detection coil at each height is calibrated according to the temperature-magnetic relationship curve, and the specific method includes: Directly multiply or subtract the magnetic induction intensity data of the standard detection coil so that the collected magnetic induction intensity data of the standard detection coil is equal to the theoretical value of the magnetic induction intensity data of the standard detection coil at the same height, and obtain the adjustment multiple of directly multiplying or subtracting the magnetic induction intensity data of the standard detection coil at each height; at each height, calibrate the magnetic induction intensity data of all non-standard detection coils using the adjustment multiple of the numerical multiplication or subtraction corresponding to the height, and obtain the calibrated magnetic induction intensity data of the non-standard detection coils at each height; At each altitude, based on the difference in temperature data and the temperature-magnetic relationship curve between the non-standard detection coil and the standard detection coil, the difference in magnetic induction intensity data between the non-standard detection coil and the standard detection coil at each altitude is calculated and recorded as the first difference at each altitude, and the sum of the first difference at each altitude and the calibrated magnetic induction intensity data of the non-standard detection coil at each altitude is used as the calibration value of the magnetic induction intensity data of the non-standard detection coil at that altitude.

[0014] The beneficial effects of the present invention are: The present application first evaluates the monotonically increasing characteristics of the magnetic induction intensity data in the transverse magnetic induction intensity sequence at the same height and the monotonically increasing characteristics of the magnetic induction intensity data in the longitudinal magnetic induction intensity sequence of the same detection coil based on the characteristics that the closer the detection coil is to the center of the detection coil disk, the stronger the magnetic field generated by the detection coil is, and the closer the distance between the detection coil disk and the detection coil is, the larger the magnetic induction intensity data collected by the detection coil is, and obtains the abnormal coefficient of each detection coil in the detection coil disk. The abnormal coefficient is an evaluation of the possibility of the detection coil and the influence of the resistance on the magnetic induction intensity data. Then, based on the abnormal coefficients of all the detection coils in the detection coil disk, the standard detection coil and the non-standard detection coil are determined, as well as the detection coil in the detection coil disk of the standard detection coil that is closest to the ideal state.

[0015] The non-standard detection coil is calibrated with the standard detection coil as the calibration standard to avoid magnetic measurement errors caused by various factors and improve the accuracy of calibration. Specifically, according to the relationship between the difference of magnetic induction intensity data at the same height and the difference of radius between the non-standard detection coil and the standard detection coil and the difference of temperature data at the same height, a second fitting curve at the same height is obtained to eliminate the influence of height on the change of magnetic induction intensity of the detection coil. Then, according to the difference between the magnetic induction intensity data differences corresponding to any two different second fitting curves at the same radius difference, a temperature-magnetic relationship point set is constructed to reflect the relationship between the magnetic induction intensity data and the temperature data, and eliminate the influence of the height and the radius of the detection coil on the relationship between the magnetic induction intensity data and the temperature data.

[0016] Furthermore, by quantitatively characterizing the weight of each point in the temperature-magnetic relationship point set, the weight is used to reflect the corresponding relationship between temperature change and magnetic induction intensity change. Then, according to the weight of each point in the temperature-magnetic relationship point set, the temperature data of the non-standard detection coil and the standard detection coil, and the magnetic induction intensity data of the non-standard detection coil and the standard detection coil, the temperature-magnetic relationship curve is obtained, so that the relationship between the more reliable magnetic induction intensity data and the temperature data has a greater impact on the fitting curve, and the obtained temperature-magnetic relationship curve is more accurate; finally, according to the temperature-magnetic relationship curve, the magnetic induction intensity data of the non-standard detection coil at each height is calibrated respectively to realize the calibration of the medical cyclotron magnetic measurement system. In the calibration process of the medical cyclotron magnetic measurement system, the influence of the internal resistance change of different detection coils on the magnetic induction intensity data is eliminated, and the problem that the internal resistance of different detection coils in the detection coil disk is different and will change, which will affect the magnetic field intensity change of the detection coil, resulting in deviation in the calibration result of the magnetic measurement system, and the poor performance of the medical cyclotron is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 A schematic flow chart of a method for calibrating a medical cyclotron magnetic measurement system provided by one embodiment of the present invention; Figure 2 A flowchart for obtaining a standard detection coil and a non-standard detection coil provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1 , which shows a flow chart of a medical cyclotron magnetic measurement system calibration method provided by an embodiment of the present invention, the method comprising the following steps: Step S001, collecting the radii of all different detection coils in the detection coil disk of the medical cyclotron, as well as the magnetic induction intensity data and temperature data of all detection coils in the detection coil disk at different heights, and obtaining the longitudinal magnetic induction intensity sequence of the same detection coil and the transverse magnetic induction intensity sequence at the same height.

[0021] The radius of each search coil in the search coil disk is measured using a position encoder.

[0022] A fiber optic temperature sensor is fixed to each detection coil in the detection coil disk, and the detection coil disk is fixed on the calibration device for cyclotron magnetic field measurement. The detection coil disk is controlled by a motor to move the detection coil disk vertically upward at a uniform speed of 1 mm / s, so that the detection coil disk gradually approaches the energized electric coil disk. At a time interval of 1 second, a fluxmeter is used to collect the magnetic induction intensity data of each detection coil in the detection coil disk during the movement of the detection coil disk. At a time interval of 1 second, a fiber optic temperature sensor is used to collect the temperature data of each detection coil in the detection coil disk during the movement of the detection coil disk.

[0023] Since the magnetic field is generated by the energized electric coil disk, when the detection coil disk moves vertically upward at a uniform speed, the distance between the detection coil disk and the energized electric coil disk becomes closer and closer.

[0024] All magnetic induction intensity data of the same detection coil in the detection coil disk are arranged in order from low to high according to the height of the magnetic induction intensity data collection, so as to obtain the longitudinal magnetic induction intensity sequence of the same detection coil.

[0025] The magnetic induction intensity data of all detection coils collected at the same height are sorted in descending order of the radius of the detection coils to obtain a transverse magnetic induction intensity sequence at the same height.

[0026] At this point, the radii of all different detection coils in the detection coil disk, the longitudinal magnetic induction intensity sequence of the same detection coil, and the transverse magnetic induction intensity sequence at the same height are obtained.

[0027] Step S002: record any one detection coil in the detection coil disk as a target detection coil, obtain the abnormal coefficient of the target detection coil according to the radius of all detection coils in the detection coil disk, the magnetic induction intensity data of all detection coils at the same height, and the correlation between the longitudinal magnetic induction intensity sequences of all detection coils, and determine the standard detection coil and the non-standard detection coil according to the abnormal coefficients of all detection coils in the detection coil disk.

[0028] The closer the detection coil is to the center of the detection coil disk, the stronger the magnetic field generated is. Therefore, the magnetic induction intensity data collected by the detection coil closer to the center of the detection coil disk is larger. Therefore, the magnetic induction intensity data in the transverse magnetic induction intensity sequence at the same height should increase monotonically. When the distance between the detection coil disk and the detection coil is closer, the magnetic induction intensity data collected by the detection coil is larger. Therefore, the magnetic induction intensity data in the longitudinal magnetic induction intensity sequence of the same detection coil should also increase monotonically.

[0029] However, the internal resistance of different detection coils in the detection coil disk is different, which will cause the magnetic induction intensity data of different detection coils to be affected by different resistances, destroying the monotonically increasing characteristics of the magnetic induction intensity data in the transverse magnetic induction intensity sequence at the same height and the longitudinal magnetic induction intensity sequence of the same detection coil, affecting the magnetic measurement system corresponding to the detection coil disk, and causing errors in the measurement results of the magnetic measurement system corresponding to the detection coil disk. Therefore, it is necessary to correct the magnetic induction intensity data according to the internal resistance of different detection coils, so that the magnetic induction intensity data in the transverse magnetic induction intensity sequence at the same height and the longitudinal magnetic induction intensity sequence of the same detection coil maintain a monotonically increasing characteristic, and eliminate the measurement result errors of the magnetic measurement system corresponding to the detection coil disk.

[0030] It should be noted that the detection coil in the magnetic measurement system will produce changes in internal resistance due to the influence of various factors. If the internal resistance of all the detection coils in the detection coil disk is measured directly, the detection coil needs to be taken out and professional instruments need to be used to measure the resistance. However, the detection coil disk of the magnetic measurement system is not suitable for measuring resistance in this way. Therefore, considering the changes in the internal resistance of the detection coil in the magnetic measurement system, this application reflects the internal resistance of all the detection coils in the detection coil disk through temperature data based on the characteristic that the temperature of the detection coil is positively correlated with the resistance.

[0031] Any detection coil in the detection coil disk is marked as the target detection coil. According to the radius of all detection coils in the detection coil disk and the magnetic induction intensity data of each detection coil at the same height, the first differential variance at the same height, the number of non-positive curvatures of the target detection coil and the second differential variance of the target detection coil at the same height are obtained.

[0032] Taking the radius of all detection coils in the detection coil disk as the independent variable and the magnetic induction intensity data of each detection coil at the same height as the dependent variable, a polynomial curve fitting algorithm is used to obtain a fitting curve of the radius of the detection coil and the magnetic induction intensity data at the same height, and the obtained fitting curve is recorded as the first fitting curve at the same height.

[0033] It can be understood that, in the process that the detection coil disk gradually approaches the energized electric coil disk, each acquisition moment corresponds to a height, and each height has a corresponding first fitting curve.

[0034] The curvatures of the points corresponding to the radii of all the detection coils in each first fitting curve are calculated respectively, and the curvatures of all the calculated points of the first fitting curve at the same height are arranged in ascending order according to the radii of the detection coils corresponding to the curvatures, so as to obtain the curvature sequence at the same height.

[0035] Any one of the detection coils in the detection coil disk is recorded as a target detection coil. This embodiment is described by taking any one of the detection coils as an example.

[0036] The number of non-positive numbers in the curvature corresponding to the target detection coil in all curvature sequences of the same height is recorded as the number of non-positive curvatures of the target detection coil.

[0037] The first-order difference sequence of the curvature sequence at the same height is recorded as the curvature difference sequence at the same height, and the variance of all data contained in the curvature difference sequence at the same height is recorded as the first difference variance at the same height.

[0038] The difference values ​​calculated from the curvatures of the points corresponding to the radii of all target detection coils in the curvature difference sequence at the same height are deleted, and the variances of all remaining difference values ​​in the curvature difference sequence at the same height are recorded as the second difference variance of the target detection coil at the same height.

[0039] The same method can be used to obtain the number of non-positive curvatures of any detection coil in the detection coil disk and the second differential variance of any detection coil in the detection coil disk at the same height. That is, any detection coil in the detection coil disk has a corresponding number of non-positive curvatures, and at the same time, any detection coil in the detection coil disk has a corresponding second differential variance at each height.

[0040] Among them, using a polynomial curve fitting algorithm to obtain a fitting curve, calculating the curvature of points on the curve, and calculating the first-order difference sequence of the sequence are all well-known technologies and will not be described in detail.

[0041] According to the number of non-positive curvatures of the detection coils, the first differential variance at the same height, the second differential variance at the same height, and the correlation between the longitudinal magnetic induction intensity sequences of all the detection coils, the abnormal coefficient of each detection coil in the detection coil disk is obtained.

[0042] In the formula, Indicates the number of detection coils in the disk The anomaly coefficient of the detection coil; Indicates the number of detection coils in the disk The number of non-positive numbers contained in the first-order difference sequence of the longitudinal magnetic induction intensity sequence of the detection coils; Indicates the number of detection coils in the disk The number of non-positive curvatures of the detection coils; represents the mean of all first difference variances of the same height; Indicates the number of detection coils in the disk The mean of the variances of the second differences of all detection coils at the same height; Indicates the first parameter of the preset, which is used to avoid When it is 0, the value of the abnormal coefficient is directly 0. In this embodiment, the value of the preset first parameter is 1; Indicates the number of detection coils in the disk The average of the absolute values ​​of the correlation coefficients between the longitudinal magnetic induction intensity sequences of a detection coil and all other detection coils.

[0043] This embodiment uses the Pearson correlation coefficient as the correlation coefficient of the longitudinal magnetic induction intensity sequence. As other implementations, on the basis of achieving the purpose of measuring the correlation between two sequences, the implementer can use other methods in the prior art to obtain the correlation between the two sequences, and this application does not impose any special restrictions.

[0044] It is for Monotonicity evaluation of the longitudinal magnetic induction intensity sequence of the detection coils, It is for The monotonicity evaluation of the longitudinal magnetic induction intensity sequence of the detection coil. When the longitudinal magnetic induction intensity sequence of the detection coils and the longitudinal magnetic induction intensity sequence completely meet the monotonically increasing characteristics, and The value of is 0. The smaller the possibility that the resistance of the first detection coil will affect the magnetic induction intensity data, the smaller the The smaller the magnetic measurement error produced by the first detection coil, the The smaller the degree of calibration of each detection coil, the smaller the The less obvious the monotonically increasing characteristics of the longitudinal magnetic induction intensity sequence of the detection coil and the longitudinal magnetic induction intensity sequence are, and The larger the value of The larger the abnormal coefficient of the first detection coil, the greater the difference between the resistance of the target detection coil and the resistance of other detection coils. The greater the possibility that the resistance of the detection coil will affect the magnetic induction intensity data, the greater the possibility that the resistance of the detection coil will affect the magnetic induction intensity data. The greater the magnetic measurement error produced by the first detection coil, the The greater the degree to which each detection coil should be calibrated.

[0045] It is an evaluation of the stability of the curvature contained in the curvature sequence of the same height. It is an evaluation of the stability of all curvatures contained in the curvature sequence at the same height, excluding the curvature of the point corresponding to the radius of the target detection coil. The smaller the value is, the smaller the difference in the stability evaluation results of all curvatures after excluding the curvature of the point corresponding to the radius of the target detection coil. The curvature of the point corresponding to the radius of the target detection coil is smaller than that of other curvatures. Therefore, the resistance of the target detection coil is more different from that of other detection coils, and the possibility that the target detection coil is affected by the resistance on the magnetic induction intensity data is smaller. The smaller the magnetic measurement error produced by the first detection coil, the The smaller the degree of calibration of each detection coil, the smaller the The smaller the abnormality coefficient of a detection coil is, the smaller the value is.

[0046] When the absolute value of the correlation coefficient between the target detection coil and the longitudinal magnetic induction intensity sequences of different detection coils is larger, the correlation between the longitudinal magnetic induction intensity sequences is more significant. At this time, the resistance of the target detection coil is less different from that of other detection coils, and the abnormal coefficient of the target detection coil is smaller.

[0047] At this point, the abnormal coefficient of each detection coil in the detection coil disk is obtained.

[0048] The magnetic induction intensity of the detection coil will be affected by many factors such as manufacturing process, resistance, operating environment, etc. The smaller the abnormal coefficient, the less affected the detection coil is by various factors. Therefore, the detection coil with the smallest abnormal coefficient is considered to be the detection coil closest to the ideal state in the detection coil disk. Using the detection coil closest to the ideal state as the calibration standard can avoid magnetic measurement errors caused by various factors to a certain extent and improve the accuracy of calibration.

[0049] The detection coil with the smallest abnormal coefficient is recorded as the standard detection coil, and the detection coil that is not the standard detection coil is recorded as the non-standard detection coil. The non-standard detection coil is calibrated according to the standard detection coil.

[0050] At this point, the standard detection coil and the non-standard detection coil are determined. The acquisition flow chart of the standard detection coil and the non-standard detection coil is as follows: Figure 2 shown.

[0051] Step S003, according to the relationship between the difference in radius between the non-standard detection coil and the standard detection coil and the difference in magnetic induction data at the same height, as well as the relationship between the difference in temperature data between the non-standard detection coil and the standard detection coil at the same height and the difference in magnetic induction data at the same height, obtain a second fitting curve at the same height, and according to the difference between the magnetic induction data differences corresponding to any two different second fitting curves when the same radius difference is taken, construct a temperature-magnetic relationship point set, and according to the two different second fitting curves corresponding to each point in the temperature-magnetic relationship point set and the difference between the temperature data of the non-standard detection coil at all heights corresponding to each point in the temperature-magnetic relationship point set, determine the weight of each point in the temperature-magnetic relationship point set, and according to the weight of each point in the temperature-magnetic relationship point set, the temperature data of the non-standard detection coil and the standard detection coil, and the magnetic induction data of the non-standard detection coil and the standard detection coil, obtain the temperature-magnetic relationship curve.

[0052] According to the relationship between the radius difference between the non-standard detection coil and the standard detection coil, the temperature data difference at the same height, and the magnetic induction intensity data difference at the same height, the second fitting curve at the same height is obtained. Specifically, the temperature data difference between the non-standard detection coil and the standard detection coil in the detection coil disk at the same height and the radius difference between the non-standard detection coil and the standard detection coil in the detection coil disk are used as independent variables, and the magnetic induction intensity data difference between the non-standard detection coil and the standard detection coil in the detection coil disk at the same height is used as the dependent variable. Multiple nonlinear regression analysis is used to obtain the second fitting curve at the same height. At the same time, the goodness of fit of each second fitting curve is obtained.

[0053] It can be understood that, in the process of the detection coil disk gradually approaching the energized electric coil disk, each acquisition moment corresponds to a height, and each height has a corresponding second fitting curve. The second fitting curve at the same height evaluates the relationship between the difference of the temperature data at the same height and the difference of the radius at the same height and the difference of the magnetic induction intensity data at the same height, so the influence of the height on the change of the magnetic induction intensity of the detection coil is eliminated.

[0054] Among them, using multivariate nonlinear regression analysis to obtain the fitting curve and calculate the goodness of fit are both well-known technologies and will not be repeated here. The goodness of fit is an indicator for evaluating the degree of fit of the fitting curve to the fitting data.

[0055] In calculating the second fitting curve at the same height, the difference in radius between each non-standard detection coil and the standard detection coil is used as the function value corresponding to the independent variable value. It can be understood that the corresponding function value is the difference in magnetic induction intensity data at the same height.

[0056] A temperature-magnetic relationship point set is constructed according to the difference between the magnetic induction intensity data differences corresponding to any two different second fitting curves when the same radius difference is taken.

[0057] The function values ​​calculated by the second fitting curve at all heights are recorded as the first intensity difference, and the difference between the radius of the non-standard detection coil and the standard detection coil corresponding to the first intensity difference is recorded as the first radius difference of the first intensity difference.

[0058] For any two different second fitting curves, the difference between the first intensity differences corresponding to the same first radius difference is calculated, and at the same time, the difference between the temperature data of the detection coil corresponding to the same first radius difference is calculated. With the difference between the first intensity differences as the ordinate and the difference between the temperature data as the abscissa, a plane rectangular coordinate system is established, and the points corresponding to the same two first radius differences are marked in the plane rectangular coordinate system, and the set consisting of all the points in the plane rectangular coordinate system is recorded as the temperature-magnetic relationship point set.

[0059] It can be understood that every two different second fitting curves can determine a point in the temperature-magnetic relationship point set. At the same time, when determining a point in the temperature-magnetic relationship point set, it is determined based on every two identical first radius differences, so every two identical first radius differences correspond to a point in the temperature-magnetic relationship point set, that is, each non-standard detection coil corresponds to a point in the temperature-magnetic relationship point set.

[0060] The points in the temperature-magnetic relationship point set reflect the relationship between the magnetic induction intensity data and the temperature data, eliminating the influence of the height and the radius of the detection coil on the relationship between the magnetic induction intensity data and the temperature data. The temperature-magnetic relationship point set is determined based on all the second fitting curves at the same height. Therefore, when the fitting effect of the second fitting curve at the same height is better, the relationship between the magnetic induction intensity data and the temperature data reflected by the points in the temperature-magnetic relationship point set is more accurate.

[0061] The standard deviation of the temperature data of the same detection coil at all heights is recorded as the temperature standard deviation of the detection coil.

[0062] The weight of each point in the temperature-magnetic relationship point set is determined according to the goodness of fit of two different second fitting curves corresponding to each point in the temperature-magnetic relationship point set and the temperature standard deviation of the non-standard detection coil corresponding to each point in the temperature-magnetic relationship point set.

[0063] In the formula, Indicates the concentration of temperature-magnetic relationship points The weight of each point; Indicates the concentration of temperature-magnetic relationship points The minimum goodness of fit of two different second fitting curves corresponding to points; represents a preset second parameter, which is used to avoid the denominator being 0 and making the fraction meaningless. In this embodiment, the value of the preset second parameter is 1; Indicates the concentration of temperature-magnetic relationship points The temperature standard deviation of the non-standard detection coil corresponding to each point.

[0064] In order to more accurately reflect the corresponding relationship between temperature changes and changes in magnetic induction intensity, a larger weight is assigned to the points with better fitting effect of the second fitting curve corresponding to the temperature-magnetic relationship point set, and a smaller weight is assigned to the points with poor fitting effect of the second fitting curve corresponding to the temperature-magnetic relationship point set. Therefore, the greater the fitting goodness of the two different second fitting curves corresponding to the point, the greater the weight of the point in the temperature-magnetic relationship point set.

[0065] When the temperature change of the non-standard detection coil is greater, the performance of the detection coil itself is more unstable, and the relationship between the magnetic induction intensity data and the temperature data obtained based on the detection coil is less reliable. At this time, the larger the temperature standard deviation of the detection coil, the smaller the weight of the corresponding point in the temperature-magnetic relationship point set, and the less accurate the corresponding relationship between the temperature change and the magnetic induction intensity change reflected by the corresponding point in the temperature-magnetic relationship point set.

[0066] The difference in temperature data between the non-standard detection coil and the standard detection coil is taken as the independent variable, the weight of the point in the temperature-magnetic relationship point concentration is taken as the weight of the independent variable corresponding to the non-standard detection coil corresponding to the point, and the difference in magnetic induction intensity data between the non-standard detection coil and the standard detection coil is taken as the dependent variable. The weighted least squares polynomial fitting algorithm is used to obtain the temperature-magnetic relationship curve.

[0067] The weight of the point in the temperature-magnetic relationship point concentration is used as the weight of the independent variable corresponding to the non-standard detection coil corresponding to the point, and the difference in temperature data between the non-standard detection coil and the standard detection coil is weighted. This can make the relationship between the more reliable magnetic induction intensity data and the temperature data have a greater impact on the fitting curve, making the obtained temperature-magnetic relationship curve more accurate.

[0068] At this point, the temperature-magnetic relationship curve is obtained.

[0069] Step S004: calibrate the magnetic induction intensity data of the non-standard detection coil at each height according to the temperature-magnetism relationship curve to achieve the calibration of the medical cyclotron magnetic measurement system.

[0070] According to the Biot-Savart law, the relationship between the excitation current and the theoretical value of the magnetic induction intensity of the standard detection coil can be determined, wherein the excitation current is the current value provided to the energized electric coil disk, so the excitation current is a known constant value.

[0071] Therefore, according to the excitation current, the theoretical value of the magnetic induction intensity data of the standard detection coil at each height can be obtained.

[0072] According to the theoretical value of the magnetic induction data of the standard detection coil at each height, the measured value of the magnetic induction data of the non-standard detection coil is calibrated. Specifically, the magnetic induction data of the standard detection coil is directly multiplied or subtracted numerically, so that the collected magnetic induction data of the standard detection coil is equal to the theoretical value of the magnetic induction data of the standard detection coil at the same height, and the adjustment multiple of the magnetic induction data of the standard detection coil at each height is obtained. At each height, the magnetic induction data of all non-standard detection coils are calibrated using the adjustment multiple of the numerical multiplication or subtraction corresponding to the height, and the calibration magnetic induction data of the non-standard detection coil at each height is obtained. Then, at each height, according to the difference in temperature data of the non-standard detection coil and the standard detection coil and the temperature-magnetic relationship curve, the difference in magnetic induction data between the non-standard detection coil and the standard detection coil at each height is calculated and recorded as the first difference at each height, and the sum of the first difference at each height and the calibration magnetic induction data of the non-standard detection coil at each height is used as the calibration value of the magnetic induction data of the non-standard detection coil at that height.

[0073] At different heights, the change in the magnetic induction intensity data of the non-standard detection coil is not linear. At the same time, the magnetic induction intensity data of the non-standard detection coil is affected by the physical properties of the non-standard detection coil, such as resistance, temperature, and radius. Therefore, calibrating the magnetic induction intensity data of the non-standard detection coil at each height separately can ensure the accuracy of error calibration.

[0074] At this point, the calibration of the medical cyclotron magnetic measurement system is completed.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calibrating a medical cyclotron magnetic measurement system, characterized in that: The method comprises the following steps: Collect the radii of all different detection coils in the detection coil disk of the medical cyclotron, as well as the magnetic induction intensity data and temperature data of all detection coils in the detection coil disk at different heights, and obtain the longitudinal magnetic induction intensity sequence of the same detection coil and the transverse magnetic induction intensity sequence at the same height; Any detection coil in the detection coil disk is recorded as a target detection coil, an abnormal coefficient of the target detection coil is obtained, and a standard detection coil and a non-standard detection coil are determined according to the abnormal coefficients of all detection coils in the detection coil disk; According to the relationship between the difference in radius between the non-standard detection coil and the standard detection coil and the difference in magnetic induction data at the same height, and the relationship between the difference in temperature data between the non-standard detection coil and the standard detection coil at the same height and the difference in magnetic induction data at the same height, a second fitting curve at the same height is obtained; according to the difference between the magnetic induction data differences corresponding to any two different second fitting curves when the same radius difference is taken, a temperature-magnetic relationship point set is constructed; according to the two different second fitting curves corresponding to each point in the temperature-magnetic relationship point set and the difference between the temperature data of the non-standard detection coil at all heights corresponding to each point in the temperature-magnetic relationship point set, a weight of each point in the temperature-magnetic relationship point set is determined; according to the weight of each point in the temperature-magnetic relationship point set, the temperature data of the non-standard detection coil and the standard detection coil, and the magnetic induction data of the non-standard detection coil and the standard detection coil, a temperature-magnetic relationship curve is obtained; The magnetic induction intensity data of the non-standard detection coil at each height are calibrated according to the temperature-magnetism relationship curve to realize the calibration of the medical cyclotron magnetic measurement system.

2. A method for calibrating a medical cyclotron magnetic measurement system according to claim 1, characterized in that: The specific method of obtaining the longitudinal magnetic induction intensity sequence of the same detection coil and the transverse magnetic induction intensity sequence at the same height includes: Arrange all magnetic induction intensity data of the same detection coil in the detection coil disk in the order of the height of the magnetic induction intensity data collection from low to high, and obtain the longitudinal magnetic induction intensity sequence of the same detection coil; The magnetic induction intensity data of all detection coils collected at the same height are sorted in descending order of the radius of the detection coils to obtain a transverse magnetic induction intensity sequence at the same height.

3. A method for calibrating a medical cyclotron magnetic measurement system according to claim 1, characterized in that: The specific method of obtaining the abnormal coefficient of the target detection coil includes: Taking the radius of all detection coils in the detection coil disk as the independent variable and the magnetic induction intensity data of each detection coil at the same height as the dependent variable, a polynomial curve fitting algorithm is used to obtain a first fitting curve at the same height; respectively calculating the curvature of the points corresponding to the radius of all detection coils in each first fitting curve, arranging the curvatures of all calculated points of the first fitting curve at the same height in the order from small to large according to the radius of the detection coil corresponding to the curvature, and obtaining the curvature sequence at the same height; Any detection coil in the detection coil disk is recorded as the target detection coil, and the number of non-positive numbers in the curvature corresponding to the target detection coil in all curvature sequences at the same height is recorded as the number of non-positive curvatures of the target detection coil; The variance of all data contained in the first-order difference sequence of the curvature sequence at the same height is recorded as the first difference variance at the same height; The difference values ​​calculated from the curvatures of the points corresponding to the radius of all target detection coils in the curvature difference sequence at the same height are deleted, and the variances of all the remaining difference values ​​in the curvature difference sequence at the same height are recorded as the second difference variance of the target detection coil at the same height; According to the number of non-positive curvatures of the detection coils, the first differential variance at the same height, the second differential variance at the same height, and the correlation between the longitudinal magnetic induction intensity sequences of all the detection coils, the abnormal coefficient of each detection coil in the detection coil disk is obtained.

4. A method for calibrating a medical cyclotron magnetic measurement system according to claim 3, characterized in that: The method of obtaining the abnormal coefficient of each detection coil in the detection coil disk according to the number of non-positive curvatures of the detection coil, the first differential variance at the same height, the second differential variance at the same height, and the correlation between the longitudinal magnetic induction intensity sequences of all the detection coils includes: In the formula, Indicates the number of detection coils in the disk The anomaly coefficient of the detection coil; Indicates the number of detection coils in the disk The number of non-positive numbers contained in the first-order difference sequence of the longitudinal magnetic induction intensity sequence of the detection coils; Indicates the number of detection coils in the disk The number of non-positive curvatures of the detection coils; represents the mean of all first difference variances of the same height; Indicates the number of detection coils in the disk The mean of the variances of the second differences of all detection coils at the same height; represents the first parameter of the preset; Indicates the number of detection coils in the disk The average of the absolute values ​​of the correlation coefficients between the longitudinal magnetic induction intensity sequences of a detection coil and all other detection coils.

5. A medical cyclotron magnetic measurement system calibration method according to claim 1, characterized in that: The specific method of determining the standard detection coil and the non-standard detection coil includes: The detection coil with the smallest abnormal coefficient is recorded as the standard detection coil, and the detection coil that is not the standard detection coil is recorded as the non-standard detection coil.

6. A medical cyclotron magnetic measurement system calibration method according to claim 1, characterized in that: The specific method for obtaining the second fitting curve at the same height is: The difference in temperature data between the non-standard detection coil and the standard detection coil in the detection coil disk at the same height and the difference in radius between the non-standard detection coil and the standard detection coil in the detection coil disk are used as independent variables, and the difference in magnetic induction intensity data between the non-standard detection coil and the standard detection coil in the detection coil disk at the same height is used as the dependent variable. Multiple nonlinear regression analysis is used to obtain the second fitting curve at the same height.

7. A method for calibrating a medical cyclotron magnetic measurement system according to claim 1, characterized in that: The specific method of constructing the temperature-magnetic relationship point set is as follows: The function values ​​calculated by the second fitting curve at all heights are recorded as the first intensity difference, and the difference between the radius of the non-standard detection coil and the standard detection coil corresponding to the first intensity difference is recorded as the first radius difference of the first intensity difference; A plane rectangular coordinate system is established by taking the difference between the first intensity difference values ​​corresponding to every two identical first radius difference values ​​in any two different second fitting curves as the ordinate, and taking the difference between the temperature data of the detection coil corresponding to every two identical first radius difference values ​​in any two different second fitting curves as the abscissa, marking the points corresponding to every two identical first radius difference values ​​in the plane rectangular coordinate system, and recording the set consisting of all points in the plane rectangular coordinate system as the temperature-magnetic relationship point set.

8. A method for calibrating a medical cyclotron magnetic measurement system according to claim 1, characterized in that: The specific method of obtaining the weight of each point in the temperature-magnetic relationship point set is as follows: Calculate the goodness of fit of each second fitting curve; The calculation formula for the weight of the temperature-magnetic relationship point concentration point is: In the formula, Indicates the concentration of temperature-magnetic relationship points The weight of each point; Indicates the concentration of temperature-magnetic relationship points The minimum goodness of fit of two different second fitting curves corresponding to points; Indicates the preset second parameter; Indicates the concentration of temperature-magnetic relationship points The temperature standard deviation of the non-standard detection coil corresponding to each point.

9. A medical cyclotron magnetic measurement system calibration method according to claim 1, characterized in that: The specific method for obtaining the temperature-magnetic relationship curve is as follows: The difference in temperature data between the non-standard detection coil and the standard detection coil is taken as the independent variable, the weight of the point is taken as the weight of the independent variable corresponding to the non-standard detection coil corresponding to the point, and the difference in magnetic induction intensity data between the non-standard detection coil and the standard detection coil is taken as the dependent variable. Weighted curve fitting is performed to obtain the temperature-magnetism relationship curve.

10. A medical cyclotron magnetic measurement system calibration method according to claim 1, characterized in that: The specific method of calibrating the magnetic induction intensity data of the non-standard detection coil at each height according to the temperature-magnetic relationship curve is as follows: Directly multiply or subtract the magnetic induction intensity data of the standard detection coil so that the collected magnetic induction intensity data of the standard detection coil is equal to the theoretical value of the magnetic induction intensity data of the standard detection coil at the same height, and obtain the adjustment multiple of directly multiplying or subtracting the magnetic induction intensity data of the standard detection coil at each height; at each height, calibrate the magnetic induction intensity data of all non-standard detection coils using the adjustment multiple of the numerical multiplication or subtraction corresponding to the height, and obtain the calibrated magnetic induction intensity data of the non-standard detection coils at each height; At each altitude, based on the difference in temperature data and the temperature-magnetic relationship curve between the non-standard detection coil and the standard detection coil, the difference in magnetic induction intensity data between the non-standard detection coil and the standard detection coil at each altitude is calculated and recorded as the first difference at each altitude, and the sum of the first difference at each altitude and the calibrated magnetic induction intensity data of the non-standard detection coil at each altitude is used as the calibration value of the magnetic induction intensity data of the non-standard detection coil at that altitude.

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