A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation

Abstract

This application relates to the technical field of medical cyclotrons, and specifically relates to a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation. The method includes: during the process of adjusting the magnetic field strength of the main magnet based on temperature information, the steps for obtaining the temperature change amount threshold are as follows: collecting the temperature in real time on the surface of the main magnet; determining the temperature difference coefficient, temperature anomaly coefficient, temperature abnormality coefficient and trend approximation value at each collection moment; comprehensively analyzing the temperature values collected by all sensors to determine the temperature difference degree and difference factor of each sensor at each collection moment; further determining the avoidance adjustment value of each sensor at each collection moment; and obtaining the temperature change amount threshold at each collection moment. This application aims to solve the problem that the magnetic field strength of the cyclotron cannot be adjusted according to the actual ambient temperature, thereby improving the beam stability and beam extraction efficiency during the operation of the medical cyclotron.

Description

Technical Field

[0001] This application relates to the technical field of medical cyclotrons, and particularly to a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation. Background Art

[0002] A cyclotron is a device that uses magnetic and electric fields to make charged particles move in a circular motion and is repeatedly accelerated by a high-frequency electric field during the motion. It is an important instrument in high-energy physics. Cyclotrons also have a wide range of applications in the medical field. For example, various electron nuclides can be produced through different nuclear reaction formulas, and then positron nuclides with different imaging functions can be synthesized to meet the needs of positron emission tomography examinations.

[0003] In order to improve the beam current capacity and stability of the main magnetic field, it is necessary to perform a certain degree of temperature compensation on the cyclotron. The prior art sets a temperature data acquisition unit at the main magnet of the cyclotron and transmits the acquired temperature data to the upper computer. The upper computer analyzes whether the temperature data exceeds the threshold. When it exceeds the threshold, an instruction is sent to adjust the excitation current of the magnetic field, thereby automatically adjusting the magnetic field strength of the main magnet to achieve the purpose of stabilizing the beam current.

[0004] Since medical cyclotrons are used in many regions, but the climates in different regions may vary greatly, in the process of adjusting the magnetic field of a medical cyclotron in the prior art, the temperature change threshold is adaptively adjusted according to the change of the ambient temperature. When the temperature data exceeds the temperature change threshold, the magnetic field strength is adjusted. However, since there are many factors causing temperature changes, including natural and non-natural factors, it may cause the temperature change threshold of the cyclotron to be adjusted too high or too low, and ultimately the magnetic field strength of the cyclotron cannot be adjusted according to the actual ambient temperature. Summary of the Invention

[0005] In view of the above, it is necessary to provide a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation. Compared with the traditional method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation, it solves the problem that the magnetic field strength of the cyclotron cannot be adjusted according to the actual ambient temperature, and thus improves the beam current stability and beam extraction efficiency during the operation of the medical cyclotron.

[0006] A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation in this application adopts the following technical solutions:

[0007] An embodiment of this application provides a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation. The method includes the following steps:

[0008] During the process of adjusting the magnetic field strength of the main magnet, the steps for obtaining the temperature change amount threshold are as follows:

[0009] Use multiple sensors to collect the temperature on the surface of the main magnet in real time;

[0010] Based on the degree of difference between the temperature values of each sensor at each acquisition moment and its neighboring moments, determine the temperature difference coefficient at each acquisition moment;

[0011] Based on the occurrence frequency of the temperature values at each acquisition moment, and in combination with the similarity of the temperature values between each acquisition moment and the historical acquisition moments, determine the temperature anomaly coefficient at each acquisition moment;

[0012] Combine the temperature difference coefficient and the temperature anomaly coefficient to obtain the temperature anomaly coefficient at each acquisition moment;

[0013] Based on the difference in the change trend of the temperature values between each acquisition moment and its neighboring acquisition moments, and in combination with the difference in the degree of dispersion of the temperature values, determine the trend approximation value at each acquisition moment;

[0014] Based on the difference in the temperature values between each sensor and all other sensors at each acquisition moment, and the difference in the temperature change speed therebetween, determine the temperature difference degree of each sensor at each acquisition moment;

[0015] Based on the trend approximation value and the temperature difference degree, obtain the difference factor of each sensor at each acquisition moment;

[0016] Based on the temperature anomaly coefficient and the difference factor, determine the avoidance adjustment value of each sensor at each acquisition moment;

[0017] Based on the avoidance adjustment value, determine the temperature change amount threshold at each acquisition moment to adjust the magnetic field strength of the cyclotron.

[0018] In one embodiment, the process for determining the temperature difference coefficient is as follows:

[0019] Calculate the mean value of the temperature values of multiple neighboring moments at each acquisition moment, and record the difference between the mean value and the temperature value at each acquisition moment as the temperature difference;

[0020] Calculate the sum of the differences in temperature values between all any two adjacent acquisition moments among multiple moments before each acquisition moment;

[0021] The temperature difference coefficient is positively correlated with the temperature difference and the sum of the differences respectively.

[0022] In one embodiment, the temperature difference coefficient is the cumulative value of the sum of the differences and the temperature difference.

[0023] In one of the embodiments, the determination process of the temperature anomaly coefficient is as follows:

[0024] Arrange the temperature values at each acquisition time and its multiple adjacent times in chronological order to form a temperature value sequence, denoted as the first sequence;

[0025] Within the adjacent days of each acquisition time, obtain the temperature value sequence at the same time as the temperature value sequence of each acquisition time, denoted as the second sequence;

[0026] Calculate the distance between the first sequence and the second sequence;

[0027] The temperature anomaly coefficient is directly proportional to the distance and inversely proportional to the occurrence frequency.

[0028] In one of the embodiments, the expression of the temperature anomaly coefficient is:

[0029] ; where is the temperature anomaly coefficient at the i-th acquisition time; is the number of occurrences of the temperature value at the i-th acquisition time among all temperature values before the i-th acquisition time; β is a preset value greater than 0; is the distance between the first sequence and the second sequence.

[0030] In one of the embodiments, the expression of the trend approximation value is:

[0031] ; where is the trend approximation value at the i-th acquisition time; is the difference in the trend intensity of the temperature value sequence between the i-th acquisition time and its adjacent time; calculate the difference between the first and last data in the temperature value sequence at each acquisition time, is the product of the difference between the i-th acquisition time and its adjacent time; is the difference in the degree of dispersion of the temperature value sequence between the i-th acquisition time and its adjacent time; exp() is the exponential function with the natural constant as the base; α is a preset value greater than 0.

[0032] In one of the embodiments, the determination process of the temperature difference degree is as follows:

[0033] Denote the sum of the differences in temperature values between each sensor and all other sensors at each acquisition time as the difference sum;

[0034] Denote the average value of the differences in temperature change rates between each sensor and all other sensors at each acquisition time as the speed average value; the temperature change rate at each acquisition time is the difference in temperature values between each acquisition time and its adjacent acquisition time;

[0035] The temperature difference degree is the fusion result of the difference sum and the average speed.

[0036] In one embodiment, the difference factor is the ratio of the temperature difference degree to the trend approximation.

[0037] In one embodiment, the process of determining the temperature change amount threshold at each acquisition moment is as follows:

[0038] Based on the average level of all the avoidance adjustment values at each acquisition moment, mark the temperature value at each acquisition moment as an unnatural temperature value or a natural temperature value;

[0039] If the temperature value at the current acquisition moment is an unnatural temperature value, do not adjust the value of the temperature change amount threshold at the current acquisition moment; otherwise, adjust the value of the temperature change amount threshold at the current acquisition moment through the host computer, where the temperature change amount threshold is a variable obtained through the host computer.

[0040] In one embodiment, the process of marking the temperature value at each acquisition moment as an unnatural temperature value or a natural temperature value is as follows:

[0041] Denote the average value of the avoidance adjustment values of all sensors at each acquisition moment as the adjustment average value;

[0042] Obtain the segmentation threshold of the adjustment average value at all acquisition moments;

[0043] If the adjustment average value at the current acquisition moment is greater than or equal to the segmentation threshold, mark all the temperature values at the current acquisition moment as unnatural temperature values; otherwise, mark them as natural temperature values.

[0044] This application has at least the following beneficial effects:

[0045] Based on the difference degree between the temperature values of each sensor at each acquisition moment and its adjacent moments, this application determines the temperature difference coefficient at each acquisition moment; by comparing the temperature differences at different time points, it can more accurately analyze whether the temperature change is caused by non-natural factors;

[0046] Based on the occurrence frequency of the temperature values at each acquisition moment, combined with the similarity of the temperature values between each acquisition moment and the historical acquisition moments, this application determines the temperature anomaly coefficient at each acquisition moment; by analyzing the similarity of each temperature value with the historical data, it can judge whether the change of the temperature value conforms to the change rule caused by natural factors;

[0047] Combining the temperature difference coefficient and the temperature anomaly coefficient, this application obtains the temperature anomaly coefficient at each acquisition moment; it reflects the possibility that the temperature value at each acquisition moment is caused by non-natural factors, and more comprehensively evaluates the inducement of the temperature change.

[0048] Based on the difference in the change trend of temperature values between each acquisition moment and its neighboring acquisition moments, and combined with the difference in the degree of dispersion of temperature values, determine the trend approximation value of each acquisition moment; based on the difference in temperature values between each sensor and all other sensors at each acquisition moment, and the difference in the temperature change rate therebetween, determine the temperature difference degree of each sensor at each acquisition moment; and then obtain the difference factor of each sensor at each acquisition moment; by the difference between the temperature values collected by different sensors at the same moment, and combined with the change trend of the temperature values collected by the same sensor, analyze the possibility that the temperature values collected by each sensor are caused by non-natural factors. Analyzing by integrating the data of different sensors can reduce misanalysis and improve the accuracy and reliability of the analysis results;

[0049] Based on the temperature anomaly coefficient and the difference factor, determine the avoidance adjustment value of each sensor at each acquisition moment; based on the avoidance adjustment value, determine the temperature change amount threshold at each acquisition moment; for the temperature change caused by non-natural factors, do not adjust the temperature change amount threshold, and for the temperature change caused by natural factors, adjust the temperature change amount threshold, and then adjust the magnetic field strength according to the temperature change amount threshold, solving the problem that the magnetic field strength of the cyclotron cannot be adjusted according to the actual ambient temperature, and further improving the beam stability and beam extraction efficiency during the operation of the medical cyclotron. Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0051] Figure 1 It is a step flow chart of a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation provided by the present application;

[0052] Figure 2 It is a schematic diagram of the determination process of the temperature difference coefficient;

[0053] Figure 3 It is a schematic diagram of the determination process of the temperature difference degree;

[0054] Figure 4 It is a schematic diagram of the acquisition process of the avoidance adjustment value. Detailed Embodiments

[0055] In the description of the embodiments of the present application, words such as "exemplary", "or", "for example", etc. are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary", "or", "for example", etc. is intended to present related concepts in a specific manner.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. It should be understood that unless otherwise specified in this application, " / " means "or".

[0057] In addition, it should be noted that the terms "first" and "second" in this application are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0058] The following specifically describes the specific solution of a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation with reference to the accompanying drawings.

[0059] A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation provided by an embodiment of the present application. Specifically, a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation is provided as follows. Please refer to Figure 1 , and the method includes the following steps:

[0060] Step 1: Use multiple sensors to collect the temperature in real time on the surface of the main magnet of the medical cyclotron.

[0061] In this application, a temperature information acquisition unit is arranged around the main magnet of the cyclotron, including multiple temperature sensors, multiple intelligent temperature acquisition modules, and an embedded serial port server. In this embodiment, both the temperature sensors and the intelligent temperature acquisition modules are 8, and the numbers of the temperature sensors and the intelligent temperature acquisition modules are preset by humans and can be set by the implementer himself / herself. This application does not make special restrictions.

[0062] The temperature sensor uses a platinum resistance PT100 and is mounted on the surface of the main magnet of the cyclotron;

[0063] The intelligent temperature acquisition module uses an eight-channel inspection instrument of BOOST (Pust) Company and can upload the temperature information through the MODBUS protocol of the RS485 communication interface;

[0064] The embedded serial server uses the DA662 of MOXA to collect on-site information and implement a dual-network redundant communication architecture. The on-site information collection includes receiving the output information of the intelligent temperature collection module.

[0065] In this application, the temperature sensor is used to measure the temperature on the surface of the main magnet, convert it into a measurable signal and output it to the intelligent temperature collection module. The intelligent temperature collection module collects and processes the output signal of the temperature sensor. Each intelligent temperature collection module collects temperature information every interval of time T, and uploads the collected temperature information to the algorithm processing unit in the upper computer through the embedded serial server.

[0066] It should be noted that the temperature information collected by the temperature information collection unit includes the temperature value at the collection moment and the specific information of the collection moment. The specific information of the collection moment is the year, month, day, hour, minute, and second when the temperature value is collected.

[0067] In this embodiment, the value of T is 10 min. The value of T is preset manually and can be set by the implementer himself / herself without special restrictions in this application.

[0068] Step 2: Determine the temperature difference coefficient at each collection moment based on the difference degree between the temperature values of each sensor at each collection moment and its adjacent moments.

[0069] In order to enable the medical cyclotron to adaptively adjust the temperature change amount threshold according to the actual working environment temperature, and then obtain the temperature change amount for adjusting the main magnet magnetic field strength, it is necessary to analyze the collected temperature information and determine the threshold of the temperature change amount according to the temperature change situation.

[0070] During the operation of the medical cyclotron, many factors will cause the temperature of its working environment to change. However, not all change situations require adjustment of the temperature change amount threshold. When the temperature change amplitude is large and the duration is long, it indicates that the ambient temperature will always affect the normal operation of the cyclotron and the temperature change amount threshold needs to be adjusted. When the temperature change amplitude is small and the duration is short, it indicates that the ambient temperature change at this time may be a short-term temperature change caused by the frequent opening and closing of the machine room door. Such temperature changes have a short duration and little impact on the operation of the cyclotron, and there is no need to adjust the temperature change amount threshold. Therefore, it is necessary to analyze the temperature change situation and extract the situations that need to be adjusted.

[0071] Taking the temperature value collected by a single temperature sensor as an example, under normal circumstances, the influencing factors of the working environment temperature change of a medical cyclotron are mainly divided into two categories. One is natural factors, such as seasonal changes and weather changes. The temperature changes caused by these factors usually have a small change range and a slow change speed. The other is non-natural factors, such as frequent opening and closing of the machine room door, and the decline in the effect of the ventilation system in maintaining the temperature in the machine room, resulting in an overall increase in the temperature of the machine room. These factors have a greater impact on the temperature change range, and the temperature change speed caused by these factors is faster.

[0072] Based on the change characteristics of the working environment temperature of the medical cyclotron under the influence of different factors, and based on the change conditions of the temperature values at each acquisition moment and its multiple adjacent acquisition moments, determine the temperature difference coefficient at each acquisition moment. The expression is:

[0073] ; In the formula, is the temperature difference coefficient at the i-th acquisition moment; Denote the preset number of acquisition moments before the i-th acquisition moment and adjacent to it as the control moments of the i-th acquisition moment, and calculate the mean value of the temperature values of all control moments of the i-th acquisition moment, is the difference between the temperature value at the i-th acquisition moment and the mean value; is the sum of the differences in temperature values between any two adjacent acquisition moments among all control moments of the i-th acquisition moment. It should be noted that during the process of calculating the temperature difference coefficient at the i-th acquisition moment, if insufficient data cannot be obtained, no processing will be performed.

[0074] In this embodiment, the value of the preset number is 10, and the value of the preset number is preset manually, and the implementer can set it by himself / herself. This application does not make special restrictions.

[0075] In this embodiment, during the process of calculating the temperature difference coefficient at the i-th acquisition moment, all the differences involved are absolute values of differences. As other implementation manners, on the basis of being able to measure the difference between the mean value and the temperature value, and the difference between two temperature values, the implementer can also adopt other calculation methods, such as ratio, square of the difference, etc. This application does not make special restrictions.

[0076] It should be noted that: the greater the change in the working environment temperature of the cyclotron, the greater the difference between the temperature value at the i-th acquisition moment and the mean value, and the greater the difference in temperature values between adjacent acquisition moments among all control moments of the i-th acquisition moment; that is, the greater the temperature difference coefficient, the more likely it is that the change in the working environment temperature of the cyclotron at this time is caused by non-natural factors. The schematic flow chart of determining the temperature difference coefficient is as Figure 2 shown.

[0077] Step 3: Based on the occurrence frequency of the temperature values at each acquisition moment and in combination with the similarity of the temperature values between each acquisition moment and the historical acquisition moments, determine the temperature anomaly coefficient for each acquisition moment.

[0078] When the working environment temperature of the cyclotron changes due to natural factors, the temperature change has a regularity. For example, the temperature is relatively low in the morning and evening, gradually rises in the morning, reaches the peak in the afternoon, and then starts to decline. The change speed is slow. Specifically, the temperature values in the morning and evening are relatively similar, while the temperature in the afternoon is higher and the change speed is slow. The temperature change caused by non-natural factors usually has no fixed pattern and the temperature change speed is fast. When a temperature change caused by non-natural factors occurs, it is specifically manifested as a peak generated by a sudden change in the temperature value, and the duration is short.

[0079] Based on the characteristics of the working environment temperature change of the cyclotron caused by non-natural factors, based on the number of times the temperature values at each acquisition moment have occurred, and the similarity of the temperature values between the day where each acquisition moment is located and its adjacent days, determine the temperature anomaly coefficient for each acquisition moment. The expression is:

[0080] ; where, is the temperature anomaly coefficient of the i-th acquisition moment; is the number of times the temperature value of the i-th acquisition moment appears among all the temperature values before the i-th acquisition moment; β is a preset value greater than 0, the purpose is to avoid the denominator being 0, the value of β is preset manually, and the implementer can set it by himself. In this embodiment, the value of β is 0.001; Arrange the temperature values of the i-th acquisition moment and all its comparison moments in time sequence to form a temperature value sequence, denoted as the first sequence. Within the day adjacent to the day where the i-th acquisition moment is located, obtain the temperature value sequence at the same moment as the temperature value sequence of the i-th acquisition moment, denoted as the second sequence. is the distance between the first sequence and the second sequence. It should be noted that during the process of calculating the temperature anomaly coefficient of the i-th acquisition moment, if insufficient data cannot be obtained, no processing is performed.

[0081] In this embodiment, the distance between the first sequence and the second sequence can be the DTW (Dynamic Time Warping) distance. As other implementation manners, on the basis of being able to measure the distance between the first sequence and the second sequence, the implementer can use other existing technologies to obtain the distance between the first sequence and the second sequence, such as Euclidean distance, Manhattan distance, etc. This application does not make special restrictions.

[0082] It should be noted that: when the temperature value at the i-th acquisition moment is caused by non-natural factors, and the lower the regularity of the temperature change caused by non-natural factors, the fewer the number of times the temperature value at the i-th acquisition moment appears before that moment, and the lower the similarity of the temperature value compared with the temperature value sequence at the same moment of the previous day, that is, the greater the temperature anomaly coefficient.

[0083] Step 4: Combine the temperature difference coefficient and the temperature anomaly coefficient to obtain the temperature anomaly coefficient at each acquisition moment.

[0084] Take the fusion result of the temperature difference coefficient and the temperature anomaly coefficient at each acquisition moment as the temperature anomaly coefficient at each acquisition moment.

[0085] It should be understood that: Fusion refers to combining multiple independent variables in a way that enhances the overall effect, such as an additive relationship, a multiplicative relationship, etc. The implementer can make limitations according to the actual situation, and this application does not make special restrictions.

[0086] In this embodiment, take the sum value of the temperature difference coefficient and the temperature anomaly coefficient at each acquisition moment as the temperature anomaly coefficient at each acquisition moment.

[0087] In another embodiment, take the product of the temperature difference coefficient and the temperature anomaly coefficient at each acquisition moment as the temperature anomaly coefficient at each acquisition moment.

[0088] It should be noted that: when the working environment temperature of the medical cyclotron is affected by non-natural factors, the greater the amplitude of the temperature change, the faster the change speed, and the lower the regularity; that is, the greater the temperature anomaly coefficient, indicating that the change in the working environment temperature of the cyclotron at this time is more likely to be caused by non-natural factors. This situation has a short influence time and a low overall influence amplitude, and it is temporarily not necessary to adjust the temperature change amount threshold of the cyclotron.

[0089] Step 5: Based on the difference in the change trend of the temperature values between each acquisition moment and its neighboring acquisition moment, and combined with the difference in the degree of dispersion of the temperature values, determine the trend approximation value at each acquisition moment.

[0090] However, under natural factors, there are also some situations that will cause the working environment temperature of the cyclotron to change rapidly in a short time. For example, cold air, rainfall, etc. will all cause the temperature to change rapidly in a short time, resulting in a decrease in the regularity of the temperature value change, and it is similar to the temperature change situation caused by non-natural factors. Therefore, only by calculating the temperature anomaly coefficient at each acquisition moment to judge the inducement of the temperature change may cause the temperature change caused by natural factors to be judged as caused by non-natural factors, and then lead to deviations when adjusting the temperature change amount threshold. Therefore, further judgment is required.

[0091] When the operating environment temperature of the cyclotron changes due to weather reasons, usually the duration is relatively long, and the temperature change situation will be close to the temperature change trend caused by natural factors. For example, when the weather turns cooler, the temperature continuously drops. When encountering cold air or rainfall, the temperature drops faster. Both show a temperature drop trend with a small degree of fluctuation. The temperature changes caused by non-natural factors vary. It may be the temperature rise caused by the frequent opening and closing of the machine room door, and the fluctuation situation within a period of time is obvious, showing a certain difference from the normal temperature change trend.

[0092] Based on the above-mentioned characteristics of the temperature value change trends caused by natural and non-natural factors, based on the differences in the temperature value change trends within the temperature value sequence between each acquisition moment and its neighboring acquisition moments, as well as the differences in the degree of temperature value change, and combined with the differences in the dispersion degree of temperature values, the trend approximation value of each acquisition moment is determined. The expression is:

[0093] ; where, is the trend approximation value of the i-th acquisition moment; is the difference in the trend intensity of the temperature value sequence between the i-th acquisition moment and its neighboring moment; Calculate the difference between the first and last data in the temperature value sequence of each acquisition moment, is the product of the above-mentioned difference between the i-th acquisition moment and its neighboring moment; is the difference in the dispersion degree of the temperature value sequence between the i-th acquisition moment and its neighboring moment; exp() is the exponential function with the natural constant as the base, aiming to map all negative values to positive values; α is a preset value greater than 0, aiming to avoid the denominator being 0. The value of α is preset by humans, and the implementer can set it by himself. In this embodiment, the value of α is 0.001. The method for obtaining the trend intensity is: decompose the temperature value sequence through the STL (Seasonal and Trend decomposition using Loess) algorithm to obtain the trend term and the residual term, and use the trend intensity formula to obtain the trend intensity of the temperature value sequence. Among them, the STL algorithm and the trend intensity formula are well-known technologies and will not be elaborated in this application. It should be noted that in the process of calculating the trend approximation value of the i-th acquisition moment, if insufficient data cannot be obtained, no processing will be performed.

[0094] In this embodiment, all the comparison moments of the i-th acquisition moment are arranged in chronological order, is the difference in the trend intensity of the temperature value sequence between the i-th acquisition moment and its first comparison moment; is the product of the above-mentioned difference between the i-th acquisition moment and its first comparison moment; is the difference in the degree of dispersion of the temperature value sequence between the i-th acquisition moment and its first reference moment. As another implementation, it can also be the difference in the trend intensity of the temperature value sequence between the i-th acquisition moment and the remaining reference moments; it can also be the product of the differences between the i-th acquisition moment and the remaining reference moments; it can also be the difference in the degree of dispersion of the temperature value sequence between the i-th acquisition moment and the remaining reference moments. This application does not make special restrictions.

[0095] In this embodiment, the degree of dispersion is the variance. As another implementation, on the basis of being able to measure the uneven distribution degree of the temperature values in the temperature value sequence, implementers can use other existing technologies for measurement, such as standard deviation, coefficient of variation, etc. This application does not make special restrictions.

[0096] In this embodiment, during the process of calculating the trend approximation value of the i-th acquisition moment, the differences involved are all the absolute values of the differences. As another implementation, on the basis of being able to measure the differences between trend intensities and the differences between degrees of dispersion, implementers can use other existing technologies for measurement, such as ratios, squares of differences, etc. This application does not make special restrictions.

[0097] It should be noted that when the change in the working environment temperature of the cyclotron is caused by natural factors, the change trends of the temperature values in two adjacent time periods are similar, and the direction of gradual change is the same, and the fluctuation conditions are similar; that is, the larger the trend approximation value, the more likely it is that the change in the working environment temperature of the cyclotron is caused by natural factors. Among them, the direction of gradual change is determined by the positive or negative of the product of the differences between the i-th acquisition moment and its first reference moment.

[0098] Step 6, based on the differences in temperature values between each sensor and all other sensors at each acquisition moment, and the differences in temperature change speeds therebetween, determine the temperature difference degree of each sensor at each acquisition moment.

[0099] Under normal circumstances, the change in the ambient temperature is overall. Under the influence of natural factors, the change in the ambient temperature will affect the entire computer room. Therefore, the temperature values collected by each temperature sensor have a small difference. When there is a change in the ambient temperature caused by non-natural factors, such as a temperature difference between the side of the cyclotron close to the computer room door and the side far from the computer room door, there is a certain difference between the temperature values collected by different temperature sensors at this time.

[0100] Based on the above analysis, based on the differences in temperature values between each sensor and all other sensors at each acquisition moment, and the differences in temperature change speeds therebetween, determine the temperature difference degree of each sensor at each acquisition moment. The expression is:

[0101] ; wherein, is the temperature difference degree of the j-th sensor at the i-th acquisition moment; is the sum of the temperature value differences between the j-th sensor and all other sensors at the i-th acquisition moment; is the average value of the differences in temperature change rates between the j-th sensor and all other sensors at the i-th acquisition moment; at the i-th acquisition moment, the temperature change rate of each sensor is the difference in temperature values between the i-th acquisition moment of each sensor and its adjacent acquisition moment.

[0102] In this embodiment, at the i-th acquisition moment, the temperature change rate of each sensor is the difference in temperature values between the i-th acquisition moment of each sensor and its adjacent previous acquisition moment. As other implementation manners, the implementer can also calculate the difference in temperature values between the i-th acquisition moment of each sensor and its adjacent subsequent acquisition moment.

[0103] In this embodiment, during the process of calculating the temperature difference degree of the j-th sensor at the i-th acquisition moment, all the involved differences are absolute values of differences. As other implementation manners, based on the measurability of the differences between temperature values and the differences between temperature change rates, the implementer can use other existing technologies for measurement, such as ratios, squares of differences, etc., and this application does not make special restrictions.

[0104] It should be noted that: when the temperature values collected by the temperature sensors at a single acquisition moment are affected by non-natural factors, there are differences in both the temperature values and the temperature change rates collected by different temperature sensors; that is, the greater the temperature difference degree, the more likely it is that the temperature values collected by the temperature sensors at this time are affected by non-natural factors. The schematic diagram of the determination process of the temperature difference degree is as Figure 3 shown.

[0105] Step 7, based on the trend approximation value and the temperature difference degree, obtain the difference factors of each sensor at each acquisition moment.

[0106] Take the ratio of the temperature difference degree of each sensor at each acquisition moment to the trend approximation value of each acquisition moment as the difference factor of each sensor at each acquisition moment.

[0107] It should be noted that: the greater the difference in temperature values between a single temperature sensor and all other temperature sensors, and the less similar the change trends of the temperature values collected by a single sensor in different time periods, it indicates that the temperature values collected by this temperature sensor are more likely to be caused by non-natural factors and need to be excluded more in the subsequent adjustment process of the temperature change amount threshold.

[0108] Step 8, based on the temperature anomaly coefficient and the difference factor, determine the avoidance adjustment value of each sensor at each acquisition moment.

[0109] Take the fusion result of the temperature anomaly coefficient at each acquisition moment and the difference factor of each sensor at each acquisition moment as the avoidance adjustment value of each sensor at each acquisition moment.

[0110] In this embodiment, take the sum value of the temperature anomaly coefficient and the difference factor as the avoidance adjustment value of each sensor at each acquisition moment.

[0111] In another embodiment, take the product of the temperature anomaly coefficient and the difference factor as the avoidance adjustment value of each sensor at each acquisition moment.

[0112] It should be noted that: when the temperature value collected by a single sensor at a single moment is more likely to be caused by non-natural factors, the temperature change situation in the working environment of the cyclotron is more likely to be caused by non-natural factors, and it is less necessary to adjust the temperature change amount threshold. The schematic diagram of the acquisition process of the avoidance adjustment value is as Figure 4 shown.

[0113] Step 9, based on the avoidance adjustment value, determine the temperature change amount threshold at each acquisition moment to adjust the magnetic field intensity of the cyclotron.

[0114] At each acquisition moment, denote the mean value of the avoidance adjustment values of all sensors as the adjustment mean value, obtain the segmentation threshold of the adjustment mean values at all acquisition moments. If the adjustment mean value at the current acquisition moment is greater than or equal to the segmentation threshold, it indicates that the change in the ambient temperature at this time is caused by non-natural factors, and mark all temperature values at the current acquisition moment as non-natural temperature values; otherwise, it indicates that the change in the ambient temperature at this time is caused by natural factors, and mark all temperature values at the current acquisition moment as natural temperature values.

[0115] In this embodiment, the Otsu threshold segmentation algorithm is used to obtain the segmentation threshold. As other implementation manners, on the basis of being able to obtain the segmentation threshold, the implementer can use other existing technologies to obtain the segmentation threshold, such as global threshold segmentation, iterative threshold segmentation, etc. This application does not make special restrictions.

[0116] Based on the above principle, the upper computer algorithm processing unit first marks the received temperature values. Subsequently, in the process of adjusting the temperature change amount threshold, if the temperature value at the current moment is a non-natural temperature value, the temperature change amount threshold is not adjusted, and the temperature change amount threshold of the previous acquisition moment is still used. If the temperature value at the current moment is a natural temperature value, the upper computer is used to obtain the temperature change amount threshold at the current moment. Among them, the process of the upper computer algorithm processing unit adjusting the temperature change amount threshold is a well-known technology, and this application will not elaborate.

[0117] Further, after the host computer algorithm processing unit obtains the temperature change threshold at each acquisition moment, it determines whether the average temperature value of all sensors at the current moment exceeds the temperature change threshold at the current moment. If it exceeds the temperature change threshold, it uses the host computer database to obtain the main magnet power supply current change instruction corresponding to the average value, and sends this instruction to the PLC control unit; after receiving the instruction, the PLC control unit generates a corresponding control pulse and sends the control pulse to the cyclotron main magnet controlled power supply unit; finally, the cyclotron main magnet controlled power supply unit receives the pulse signal in real time, thereby adjusting the magnetic field strength of the main magnet to make the beam current stable; otherwise, no subsequent processing is performed.

[0118] In summary, based on the degree of difference in temperature values of each sensor at each acquisition moment and its adjacent moments, the temperature difference coefficient at each acquisition moment is determined; by comparing the temperature differences at different time points, it is possible to more accurately analyze whether the temperature change is caused by non-natural factors;

[0119] Further, based on the occurrence frequency of the temperature values at each acquisition moment, combined with the similarity of the temperature values between each acquisition moment and the historical acquisition moments, the temperature anomaly coefficient at each acquisition moment is determined; by analyzing the similarity of each temperature value with the historical data, it is judged whether the change of the temperature value conforms to the change law that occurs due to natural factors;

[0120] Further, by combining the temperature difference coefficient and the temperature anomaly coefficient, the temperature anomaly coefficient at each acquisition moment is obtained; it reflects the possibility that the temperature value at each acquisition moment is caused by non-natural factors, and comprehensively evaluates the inducement of temperature change;

[0121] Further, based on the difference in the change trend of the temperature values between each acquisition moment and its adjacent acquisition moments, and combined with the difference in the degree of dispersion of the temperature values, the trend approximation value at each acquisition moment is determined; based on the difference in the temperature values between each sensor and all other sensors at each acquisition moment, and the difference in the temperature change speed therebetween, the temperature difference degree of each sensor at each acquisition moment is determined; and then the difference factor of each sensor at each acquisition moment is obtained; by the difference between the temperature values collected by different sensors at the same moment, and combined with the change trend of the temperature values collected by the same sensor, it analyzes the possibility that the temperature values collected by each sensor are caused by non-natural factors. By comprehensively analyzing the data of different sensors, misanalysis can be reduced, and the accuracy and reliability of the analysis results can be improved;

[0122] Further, based on the temperature anomaly coefficient and the difference factor, determine the avoidance adjustment value of each sensor at each acquisition moment; based on the avoidance adjustment value, determine the temperature change threshold at each acquisition moment; for the temperature change caused by non-natural factors, do not adjust the temperature change threshold, and for the temperature change caused by natural factors, adjust the temperature change threshold, and then adjust the magnetic field strength according to the temperature change threshold, solving the problem that the magnetic field strength of the cyclotron cannot be adjusted according to the actual ambient temperature, and further improving the beam stability and beam extraction efficiency during the operation of the medical cyclotron.

[0123] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to embodiments of the present disclosure. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a part of code, which contains one or more executable instructions for implementing the specified logical function. In some alternative implementations, the functions marked in the block may occur in a different order than marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. In the description corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. Each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0124] For those skilled in the art, it is obvious that this application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the basic characteristics of this application. Therefore, from any point of view, the above embodiments of this application should be regarded as exemplary and non-limiting.

Claims

1. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation, characterized in that: The method comprises the following steps: In the process of adjusting the magnetic field strength of the main magnet, the steps for obtaining the temperature change threshold are as follows: Use multiple sensors to collect temperature on the main magnet surface in real time; Determine the temperature difference coefficient at each acquisition moment based on the difference between the temperature value of each sensor at each acquisition moment and its adjacent moments; Arrange the temperature values ​​of each acquisition moment and its adjacent moments in time sequence to form a temperature value sequence, which is recorded as the first sequence; obtain the temperature value sequence at the same time as the temperature value sequence of each acquisition moment within the adjacent days of each acquisition moment, which is recorded as the second sequence; calculate the distance between the first sequence and the second sequence; calculate the temperature anomaly coefficient according to the distance and the number of occurrences; The expression of the temperature anomaly coefficient is: ; In the formula, is the temperature anomaly coefficient at the i-th acquisition moment; is the number of occurrences of the temperature value at the i-th collection moment in all temperature values ​​before the i-th collection moment; β is a value preset to be greater than 0; is the distance between the first sequence and the second sequence; Combining the temperature difference coefficient with the temperature anomaly coefficient, obtaining the temperature anomaly coefficient at each acquisition time; Based on the difference in the change trend of the temperature value between each collection time and its neighboring collection time, and combined with the difference in the degree of dispersion of the temperature value, the trend approximation value of each collection time is determined; The expression of the trend approximation is: ; In the formula, is the trend approximation at the i-th acquisition moment; is the difference in the trend strength of the temperature value sequence between the ith collection moment and its adjacent moments; calculate the difference between the first and last data in the temperature value sequence at each collection moment, is the product of the difference between the i-th acquisition moment and its adjacent moments; is the difference in the discrete degree of the temperature value sequence between the i-th acquisition moment and its adjacent moments; exp() is an exponential function with a natural constant as the base; α is a value preset to be greater than 0; Based on the difference in temperature value between each sensor and all other sensors at each acquisition moment, and the difference in temperature change speed between them, determine the temperature difference of each sensor at each acquisition moment; Based on the trend approximation and the temperature difference, obtaining a difference factor of each sensor at each acquisition time; Based on the temperature anomaly coefficient and the difference factor, determining an avoidance adjustment value of each sensor at each acquisition moment; Based on the avoidance adjustment value, a temperature change threshold at each acquisition moment is determined to adjust the magnetic field strength of the cyclotron.

2. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 1, characterized in that: The determination process of the temperature difference coefficient is: Calculate the average of the temperature values ​​at multiple adjacent moments of each acquisition moment, and record the difference between the average and the temperature value at each acquisition moment as the temperature difference; Calculate the sum of the differences in temperature values ​​between any two adjacent acquisition moments in a plurality of moments before each acquisition moment; The temperature difference coefficient is positively correlated with the temperature difference and the sum of the differences respectively.

3. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 2, characterized in that: The temperature difference coefficient is a cumulative value of the sum of the differences and the temperature difference.

4. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 1, characterized in that: The process of determining the temperature difference is as follows: The sum of the differences in temperature values ​​between each sensor and all other sensors at each acquisition time is recorded as the difference sum; The average value of the difference in temperature change rate between each sensor and all other sensors at each acquisition time is recorded as the speed average; The temperature change rate at each acquisition time is the difference between the temperature value at each acquisition time and its adjacent acquisition time; The temperature difference is a fusion result of the difference and the speed mean.

5. The method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation according to claim 1, characterized in that: The difference factor is a ratio of the temperature difference to the trend approximation.

6. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 1, characterized in that: The process of determining the temperature change threshold at each acquisition moment is as follows: Based on an average level of all the adjustment-avoiding values ​​at each collection moment, marking the temperature value at each collection moment as an unnatural temperature value or a natural temperature value; If the temperature value at the current collection moment is a non-natural temperature value, the value of the temperature change threshold at the current collection moment is not adjusted; otherwise, the value of the temperature change threshold at the current collection moment is adjusted by the host computer, where the temperature change threshold is a variable obtained by the host computer.

7. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 6, characterized in that: The process of marking the temperature value at each acquisition moment as an unnatural temperature value or a natural temperature value is as follows: The average of the avoided adjustment values ​​of all sensors at each collection time is recorded as the adjustment average value; Obtaining a segmentation threshold of the adjusted mean at all acquisition moments; If the adjusted mean value at the current collection time is greater than or equal to the segmentation threshold, all temperature values ​​at the current collection time are marked as unnatural temperature values; Otherwise, mark it as natural temperature value.

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