Medical cyclotron magnetic field intensity adjusting method based on temperature compensation

Abstract

The invention relates to the technical field of medical cyclotrons, in particular to a medical cyclotron magnetic field intensity adjusting method based on temperature compensation, and the method comprises the following steps: in the process of adjusting the magnetic field intensity of a main magnet based on temperature information, obtaining a temperature variation threshold: collecting the temperature on the surface of the main magnet in real time; determining a temperature difference coefficient, a temperature anomalous coefficient, a temperature abnormal coefficient and a trend approximate value of each acquisition moment; comprehensively analyzing the temperature values acquired by all the sensors, and determining the temperature difference degree and difference factor of each sensor at each acquisition moment; determining the avoiding adjustment value of each sensor at each acquisition moment; and acquiring a temperature variation threshold value at each acquisition moment. The invention aims to solve the problem that the magnetic field intensity of the cyclotron cannot be adjusted according to the actual environment temperature, so that the beam stability and the beam extraction efficiency in the operation process of the medical cyclotron are improved.

Description

Technical Field

[0001] The present application relates to the technical field of medical cyclotron accelerators, and in particular to a method for adjusting the magnetic field strength of a medical cyclotron accelerator based on temperature compensation. Background Art

[0002] A cyclotron accelerator 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. It is an important instrument in high-energy physics. Cyclotrons are also widely used in the medical field, such as producing a variety of electron nuclides through different nuclear reactions, and then synthesizing positron nuclides with different imaging functions to meet the needs of positron emission tomography.

[0003] In order to improve the beam capacity and stability of the main magnetic field, it is necessary to perform a certain degree of temperature compensation on the cyclotron. In the prior art, a temperature data acquisition unit is set at the main magnet of the cyclotron, and the collected temperature data is transmitted to a host computer. The host computer analyzes whether the temperature data exceeds a threshold value. When the threshold value is exceeded, 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.

[0004] Since medical cyclotrons are used in many regions, but the climates in different regions may vary greatly, the existing technology will adaptively adjust the temperature change threshold according to the changes in ambient temperature during the process of adjusting the magnetic field of the medical cyclotron. When the temperature data exceeds the temperature change threshold, the magnetic field strength is adjusted. However, since there are many factors that cause temperature changes, including natural factors and unnatural factors, the temperature change threshold of the cyclotron may be adjusted too high or too low, ultimately resulting in the inability to adjust the magnetic field strength of the cyclotron according to the actual ambient temperature. Summary of the invention

[0005] In view of the above, it is necessary to provide a medical cyclotron magnetic field strength adjustment method based on temperature compensation. Compared with the traditional medical cyclotron magnetic field strength adjustment method based on temperature compensation, it solves the problem that the cyclotron magnetic field strength 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.

[0006] A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation in the present application adopts the following technical solution: An embodiment of the present application provides a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation, the method comprising 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; Based on the frequency of occurrence of temperature values ​​at each collection time, combined with the similarity of temperature values ​​between each collection time and historical collection times, the temperature anomaly coefficient at each collection time is determined; 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; 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 the avoidance adjustment value of each sensor at each acquisition time; 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.

[0007] In one embodiment, the temperature difference coefficient is determined as follows: 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.

[0008] In one embodiment, the temperature difference coefficient is a cumulative value of the sum of the differences and the temperature difference.

[0009] In one embodiment, the process of determining the temperature anomaly coefficient is: 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; In the adjacent days of each collection time, a temperature value sequence at the same time as the temperature value sequence at each collection time is obtained, which is recorded as the second sequence; Calculating the distance between the first sequence and the second sequence; The temperature anomaly coefficient is proportional to the distance and inversely proportional to the occurrence frequency.

[0010] In one embodiment, 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.

[0011] In one embodiment, 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 degree of discreteness of the temperature value sequence between the ith acquisition moment and its adjacent moments; exp() is an exponential function with a natural constant as the base; α is a preset value greater than 0.

[0012] In one embodiment, the temperature difference is determined by: 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 of the differences in the temperature change speeds between each sensor and all other sensors at each acquisition time is recorded as the speed average; the temperature change speed at each acquisition time is the difference in the temperature value between each acquisition time and its adjacent acquisition time; The temperature difference is a fusion result of the difference and the speed mean.

[0013] In one embodiment, the difference factor is a ratio of the temperature difference to the trend approximation.

[0014] In one embodiment, 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.

[0015] 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: 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, they are marked as natural temperature values.

[0016] This application has at least the following beneficial effects: This application determines the temperature difference coefficient at each acquisition time based on the difference between the temperature value of each sensor at each acquisition time and its adjacent time; by comparing the temperature difference at different time points, it is possible to more accurately analyze whether the temperature change is caused by unnatural factors; Based on the frequency of occurrence of temperature values ​​at each collection moment, combined with the similarity of temperature values ​​between each collection moment and historical collection moments, the temperature anomaly coefficient at each collection moment is determined; by analyzing the similarity between each temperature value and historical data, it is determined whether the change of temperature values ​​conforms to the change law caused by natural factors; Combining the temperature difference coefficient with the temperature anomaly coefficient, the temperature anomaly coefficient at each acquisition time is obtained; reflecting the possibility that the temperature value at each acquisition time is caused by unnatural factors, and more comprehensively evaluating the cause of temperature change; Based on the difference in the changing trend of the temperature value between each acquisition moment and its neighboring acquisition moments, and combined with the difference in the discrete degree of the temperature value, the trend approximation value of each acquisition moment is determined; based on the difference in the temperature value between each sensor and all other sensors at each acquisition moment, and the difference in the temperature change speed between them, 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; through the difference between the temperature values ​​collected by different sensors at the same time, and combined with the changing trend of the temperature value collected by the same sensor, the possibility of the temperature value collected by each sensor being caused by non-natural factors is analyzed, and the data of different sensors are combined for analysis, which can reduce misanalysis and improve the accuracy and reliability of the analysis results; Based on the temperature anomaly coefficient and the difference factor, the avoidance adjustment value of each sensor at each acquisition moment is determined; based on the avoidance adjustment value, the temperature change threshold at each acquisition moment is determined; for temperature changes caused by non-natural factors, the temperature change threshold is not adjusted, and for temperature changes caused by natural factors, the temperature change threshold is adjusted, and then the magnetic field strength is adjusted according to the temperature change threshold, which solves the problem that the magnetic field strength of the cyclotron cannot be adjusted according to the actual ambient temperature, and then improves the beam stability and beam extraction efficiency during the operation of the medical cyclotron. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 1 A flowchart of the steps of a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation provided in this application; Figure 2 Schematic diagram of the process for determining the temperature difference coefficient; Figure 3 Schematic diagram of the process of determining the temperature difference; Figure 4 Schematic diagram of the process flow to avoid adjusting the value. DETAILED DESCRIPTION

[0019] In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" and the like are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "or", "for example" and the like is intended to present related concepts in a concrete manner.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the present application. The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. It should be understood that, unless otherwise specified, " / " means or.

[0021] It should also be noted that the terms "first" and "second" in the present application are used to distinguish similar objects rather than to describe a specific order or sequence.

[0022] The specific scheme of a method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation provided by the present application is described in detail below in conjunction with the accompanying drawings.

[0023] An embodiment of the present application provides a method for adjusting the magnetic field strength of a medical cyclotron accelerator based on temperature compensation. Specifically, the following method for adjusting the magnetic field strength of a medical cyclotron accelerator based on temperature compensation is provided. Figure 1 , the method comprises the following steps: Step 1: Use multiple sensors to collect real-time temperature on the surface of the main magnet of the medical cyclotron.

[0024] In the present application, a temperature information acquisition unit is arranged around the main magnet of the cyclotron accelerator, including multiple temperature sensors, multiple intelligent temperature acquisition modules, and an embedded serial port server. In the present embodiment, there are 8 temperature sensors and 8 intelligent temperature acquisition modules. The number of temperature sensors and intelligent temperature acquisition modules is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0025] The temperature sensor adopts a platinum resistor PT100 and is mounted on the surface of the cyclotron main magnet; The intelligent temperature acquisition module adopts BOOST's eight-way inspection instrument, which can upload temperature information through the RS485 communication interface MODBUS protocol; The embedded serial port server adopts DA662 of MOXA company, which can collect on-site information and realize dual-network redundant communication architecture. The on-site information collection includes receiving the output information of the intelligent temperature collection module; In the present application, the temperature sensor is used to measure the temperature of the surface of the main magnet, and converts it into a measurable signal and outputs it to the intelligent temperature acquisition module. The intelligent temperature acquisition module collects and processes the output signal of the temperature sensor. Each intelligent temperature acquisition module collects temperature information once every time interval T, and uploads the collected temperature information to the algorithm processing unit in the host computer through the embedded serial port server.

[0026] It should be noted that the temperature information collected by the temperature information collection unit includes the temperature value at the collection time and the specific information at the collection time, and the specific information at the collection time is the year, month, day, hour, minute and second when the temperature value is collected.

[0027] In this embodiment, the value of T is 10 minutes. The value of T is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0028] Step 2: Determine the temperature difference coefficient at each collection moment based on the degree of difference between the temperature value of each sensor at each collection moment and its adjacent moments.

[0029] In order to enable the medical cyclotron to adaptively adjust the temperature change threshold according to the actual working environment temperature and thereby obtain the temperature change used to adjust the magnetic field strength of the main magnet, it is necessary to analyze the collected temperature information and determine the temperature change threshold according to the temperature change.

[0030] During the operation of a medical cyclotron, there are many factors that can cause the temperature of its working environment to change, but not all changes require adjustment of the temperature change threshold. When the temperature change is large and lasts for a long time, it means that the ambient temperature will always affect the normal operation of the cyclotron, and the temperature change threshold needs to be adjusted. When the temperature change is small and lasts for a short time, it means 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. This type of temperature change lasts for a short time and has little impact on the operation of the cyclotron, so there is no need to adjust the temperature change threshold. Therefore, it is necessary to analyze the temperature changes and extract the situations that need to be adjusted.

[0031] Taking the temperature value collected by a single temperature sensor as an example, under normal circumstances, the factors affecting the temperature change of the working environment of the medical cyclotron can be divided into two main categories. One is natural factors, such as seasonal changes, weather changes, etc. The temperature changes caused by these factors are usually small in amplitude and slow in speed. The other is unnatural factors, such as frequent opening and closing of the machine room door, which reduces the effectiveness 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 amplitude of temperature changes, and the temperature changes caused by these factors are faster.

[0032] Based on the change characteristics of the working environment temperature of the medical cyclotron under the influence of different factors, the temperature difference coefficient of each acquisition moment is determined based on the change of the temperature value at each acquisition moment and its multiple neighboring acquisition moments. The expression is: ; In the formula, is the temperature difference coefficient at the ith collection moment; the preset number of collection moments before and adjacent to the ith collection moment are recorded as the control moments of the ith collection moment, and the mean of the temperature values ​​of all control moments of the ith collection moment is calculated, is the difference between the temperature value at the i-th acquisition moment and the mean value; It is the sum of the differences in temperature values ​​between any two adjacent acquisition moments in all comparison moments of the i-th acquisition moment. It should be noted that in the process of calculating the temperature difference coefficient of the i-th acquisition moment, if sufficient data cannot be obtained, no processing is performed.

[0033] In this embodiment, the value of the preset number is 10. The value of the preset number is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0034] In this embodiment, in the process of calculating the temperature difference coefficient at the i-th acquisition moment, the differences involved are all absolute values ​​of the differences. As other implementation methods, on the basis of being able to measure the difference between the mean and the temperature value, and the difference between two temperature values, the implementer may also adopt other calculation methods, such as ratio, square of the difference, etc., and this application does not impose any special restrictions.

[0035] It should be noted that: if the change in the working environment temperature of the cyclotron is greater, the difference between the temperature value at the i-th acquisition moment and the mean value will be greater, and the difference in the temperature values ​​between adjacent acquisition moments in all the control moments of the i-th acquisition moment will be greater; that is, the greater the temperature difference coefficient, the more likely the change in the working environment temperature of the cyclotron at this time is a temperature change caused by non-natural factors. The flow chart for determining the temperature difference coefficient is as follows: Figure 2 shown.

[0036] Step 3: Based on the occurrence frequency of the temperature value at each collection moment and in combination with the similarity of the temperature value between each collection moment and the historical collection moment, determine the temperature anomaly coefficient at each collection moment.

[0037] When the working environment temperature of the cyclotron changes due to natural factors, the temperature changes regularly. For example, the temperature is relatively low in the morning and evening, gradually rises in the morning, reaches a peak in the afternoon, and then begins to decline. The change speed is slow. Specifically, the temperature values ​​in the morning and evening are similar, but higher in the afternoon, and the change speed is slow. However, the temperature changes caused by non-natural factors usually have no fixed rules, and the temperature changes quickly. When the temperature changes caused by non-natural factors occur, it is specifically manifested as a peak caused by a sudden change in the temperature value, which lasts for a short time.

[0038] Based on the characteristics of the temperature change of the cyclotron working environment caused by non-natural factors, the number of times the temperature value at each acquisition time has appeared, and the similarity of the temperature values ​​between the day of each acquisition time and its adjacent days, the temperature anomaly coefficient at each acquisition time is determined, and the expression 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 ith collection moment in all temperature values ​​before the ith collection moment; β is a preset value greater than 0, the purpose of which is to avoid the denominator being 0. The value of β is preset manually and can be set by the implementer. In this embodiment, the value of β is 0.001; the temperature values ​​at the ith collection moment and all the control moments are arranged in chronological order to form a temperature value sequence, which is recorded as the first sequence. In the previous day of the ith collection moment, a temperature value sequence at the same time as the temperature value sequence at the ith collection moment is obtained, which is recorded as the second sequence. is the distance between the first sequence and the second sequence. It should be noted that, in the process of calculating the temperature anomaly coefficient at the i-th acquisition moment, if sufficient data cannot be obtained, no processing is performed.

[0039] In this embodiment, the distance between the first sequence and the second sequence may be a DTW (Dynamic TimeWarping) distance. As another implementation, on the basis of being able to measure the distance between the first sequence and the second sequence, the implementer may adopt other existing technologies to obtain the distance between the first sequence and the second sequence, such as Euclidean distance, Manhattan distance, etc., and this application does not impose any special restrictions.

[0040] It should be noted that: when the temperature value at the i-th collection moment is caused by non-natural factors, the lower the regularity of the temperature change caused by non-natural factors, the fewer times the temperature value at the i-th collection moment appears before that moment, and compared with the temperature value sequence at the same time of the previous day, the similarity of the temperature value is lower, that is, the larger the temperature anomaly coefficient.

[0041] Step 4: combining the temperature difference coefficient and the temperature anomaly coefficient to obtain the temperature anomaly coefficient at each acquisition time.

[0042] The fusion result of the temperature difference coefficient and the temperature anomaly coefficient at each collection time is taken as the temperature anomaly coefficient at each collection time.

[0043] 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 may limit it according to the actual situation, and this application does not impose any special restrictions.

[0044] In this embodiment, the sum of the temperature difference coefficient and the temperature anomaly coefficient at each collection moment is taken as the temperature anomaly coefficient at each collection moment.

[0045] In another embodiment, the product of the temperature difference coefficient at each acquisition moment and the temperature anomaly coefficient is used as the temperature anomaly coefficient at each acquisition moment.

[0046] 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 larger the temperature anomaly coefficient, the more likely the change in the working environment temperature of the cyclotron is to be caused by non-natural factors. In this case, the impact time is shorter and the overall impact amplitude is lower. There is no need to adjust the temperature change threshold of the cyclotron for the time being.

[0047] Step 5: Based on the difference in the change trend of the temperature value between each collection moment and its neighboring collection moments and in combination with the difference in the degree of dispersion of the temperature values, determine the trend approximation value of each collection moment.

[0048] 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 period of time, such as cold air, rainfall, etc., which will cause the temperature to change rapidly in a short period of time, and then cause the regularity of the temperature value to decrease, and it is similar to the temperature change caused by non-natural factors. Therefore, judging the cause of temperature change only by calculating the temperature anomaly coefficient at each acquisition moment may lead to the temperature change caused by natural factors being judged as non-natural factors, which will lead to deviations when adjusting the temperature change threshold, so further judgment is needed.

[0049] When the working environment temperature of the cyclotron changes due to weather reasons, it usually lasts for a long time, and the temperature change is close to the temperature change trend caused by natural factors. For example, when the weather turns cooler, the temperature continues to drop. When encountering cold air or rain, the temperature drops faster. Both show a temperature drop trend with a small fluctuation. The temperature changes caused by non-natural factors are different. It may be that the temperature rises due to frequent opening and closing of the machine room door. The fluctuations over a period of time are obvious, which is different from the normal temperature change trend.

[0050] Based on the change trend characteristics of the temperature values ​​caused by the above natural and non-natural factors, based on the difference in the change trend of the temperature values ​​in the temperature value sequence between each acquisition moment and its neighboring acquisition moments, and the difference in the degree of change of the temperature values, combined with the difference in the discrete degree of the temperature values, the trend approximation value of each acquisition moment is determined, and the expression 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; It is the difference in the degree of discreteness 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, and its purpose is to map all negative values ​​to positive values; α is a preset value greater than 0, and its purpose is to avoid the denominator being 0. The value of α is preset by humans and can be set by the implementer. In this embodiment, the value of α is 0.001. The trend intensity is obtained by decomposing the temperature value sequence through the STL (Seasonal and Trend decomposition using Loess) algorithm to obtain the trend term and the residual term, and using 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 this application will not repeat them. It should be noted that in the process of calculating the trend approximation value of the i-th acquisition moment, if sufficient data cannot be obtained, no processing is performed.

[0051] In this embodiment, all the comparison moments of the i-th collection moment are arranged in time sequence. is the difference in trend strength of the temperature value sequence between the ith acquisition moment and its first control moment; is the product of the difference between the ith acquisition moment and its first comparison moment; is the difference in the discreteness of the temperature value sequence between the i-th collection moment and its first comparison moment. As another implementation, It can also be the difference in trend strength of the temperature value sequence between the i-th acquisition moment and the remaining control moments; It can also be the product of the difference between the i-th collection time and the remaining control time; It may also be the difference in the degree of discreteness of the temperature value sequence between the i-th collection moment and the remaining reference moments, and this application does not impose any special limitation.

[0052] In this embodiment, the degree of discreteness is the variance. As other implementation methods, on the basis of being able to measure the uneven distribution of temperature values ​​in a temperature value sequence, the implementer may use other existing technologies for measurement, such as standard deviation, coefficient of variation, etc., and this application does not impose any special restrictions.

[0053] In this embodiment, in the process of calculating the trend approximation value of the i-th collection moment, the differences involved are all absolute values ​​of the differences. As other implementation methods, on the basis of measurable differences between trend strengths and differences between discrete degrees, implementers can use other existing technologies for measurement, such as ratios, squares of differences, etc., and this application does not impose any special restrictions.

[0054] 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 similar time periods are similar, and the change direction is consistent, and the fluctuation is similar; that is, the larger the trend approximation value, the more likely the change in the working environment temperature of the cyclotron is caused by natural factors. Among them, the change direction is determined by the positive or negative product of the difference between the i-th acquisition moment and its first comparison moment.

[0055] Step 6: Determine the temperature difference of each sensor at each collection moment based on the difference in temperature value between each sensor and all other sensors at each collection moment, and the difference in temperature change speed between them.

[0056] Under normal circumstances, the change of ambient temperature is overall. Under the influence of natural factors, the change of ambient temperature will affect the entire computer room, so the difference in temperature values ​​collected by each temperature sensor is small. However, when there are changes in ambient temperature caused by unnatural factors, such as the temperature difference between the side of the cyclotron close to the computer room door and the side far from the computer room door, there will be a certain difference between the temperature values ​​collected by different temperature sensors.

[0057] Based on the above analysis, based on the difference in temperature values ​​between each sensor and all other sensors at each acquisition time, as well as the difference in temperature change speed between them, the temperature difference of each sensor at each acquisition time is determined, and the expression is: ; In the formula, is the temperature difference of the jth sensor at the i-th acquisition time; is the sum of the temperature differences between the jth sensor and all other sensors at the i-th acquisition moment; is the average of the differences in temperature change rates between the jth sensor and all other sensors at the i-th acquisition moment; the temperature change rate of each sensor at the i-th acquisition moment is the difference in temperature value between each sensor at the i-th acquisition moment and its adjacent acquisition moment.

[0058] In this embodiment, at the i-th acquisition moment, the temperature change rate of each sensor is the difference between the temperature value of each sensor at the i-th acquisition moment and its adjacent previous acquisition moment. As another implementation method, the implementer may also calculate the difference between the temperature value of each sensor at the i-th acquisition moment and its adjacent next acquisition moment.

[0059] In this embodiment, in the process of calculating the temperature difference of the j-th sensor at the i-th collection time, the differences involved are all absolute values ​​of the differences. As other implementation methods, on the basis of the differences between measurable temperature values ​​and the differences between the temperature change rates, the implementer may adopt other existing technologies for measurement, such as ratios, squares of differences, etc., and this application does not impose any special restrictions.

[0060] It should be noted that: when the temperature value collected by the temperature sensor at a single collection time is affected by non-natural factors, there are differences in the temperature values ​​and temperature change rates collected by different temperature sensors; that is, the greater the temperature difference, the more likely the temperature value collected by the temperature sensor is affected by non-natural factors. The schematic diagram of the temperature difference determination process is as follows Figure 3 shown.

[0061] Step 7: Based on the trend approximation and the temperature difference, obtain the difference factor of each sensor at each acquisition time.

[0062] The ratio of the temperature difference of each sensor at each acquisition time to the trend approximation value at each acquisition time is used as the difference factor of each sensor at each acquisition time.

[0063] It should be noted that: when the difference in temperature value between a single temperature sensor and the other temperature sensors is greater, and the change trend of the temperature values ​​collected by a single sensor in different time periods is more dissimilar, it means that the temperature value collected by the temperature sensor at this time is more likely to be caused by non-natural factors, and it is more necessary to eliminate it in the subsequent temperature change threshold adjustment process.

[0064] Step 8: Determine the avoidance adjustment value of each sensor at each acquisition moment based on the temperature anomaly coefficient and the difference factor.

[0065] The fusion result of the temperature anomaly coefficient at each acquisition moment and the difference factor of each sensor at each acquisition moment is used as the avoidance adjustment value of each sensor at each acquisition moment.

[0066] In this embodiment, the sum of the temperature anomaly coefficient and the difference factor is used as the avoidance adjustment value of each sensor at each collection moment.

[0067] In another embodiment, the product of the temperature anomaly coefficient and the difference factor is used as the avoidance adjustment value of each sensor at each acquisition moment.

[0068] 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 unnatural factors, the temperature change in the cyclotron working environment is more likely to be caused by unnatural factors, and there is no need to adjust the temperature change threshold. Figure 4shown.

[0069] Step 9: Determine the temperature change threshold at each acquisition moment based on the avoidance adjustment value to adjust the magnetic field strength of the cyclotron.

[0070] The average of the avoided adjustment values ​​of all sensors at each collection moment is recorded as the adjustment mean, and the segmentation threshold of the adjustment mean at all collection moments is obtained. If the adjustment mean at the current collection moment is greater than or equal to the segmentation threshold, it means that the change in ambient temperature at this time is caused by unnatural factors, and all temperature values ​​at the current collection moment are marked as unnatural temperature values; otherwise, it means that the change in ambient temperature at this time is caused by natural factors, and all temperature values ​​at the current collection moment are marked as natural temperature values.

[0071] In this embodiment, the Otsu threshold segmentation algorithm is used to obtain the segmentation threshold. As other implementation methods, on the basis of being able to obtain the segmentation threshold, the implementer may adopt other existing technologies to obtain the segmentation threshold, such as global threshold segmentation, iterative threshold segmentation, etc., and this application does not impose any special restrictions.

[0072] Based on the above principle, the host computer algorithm processing unit first marks the received temperature value. In the subsequent process of adjusting the temperature change threshold, if the temperature value at the current moment is a non-natural temperature value, the temperature change threshold is not adjusted, and the temperature change threshold at the last acquisition moment is still used. If the temperature value at the current moment is a natural temperature value, the host computer is used to obtain the temperature change threshold at the current moment. Among them, the process of the host computer algorithm processing unit adjusting the temperature change threshold is a well-known technology, and this application will not repeat it.

[0073] Furthermore, after the host computer algorithm processing unit obtains the temperature change threshold at each acquisition moment, it determines whether the average value of the temperature values ​​of all sensors at the current moment exceeds the temperature change threshold at the current moment. If it exceeds the temperature change threshold, the host computer database is used to obtain the main magnet power supply current change instruction corresponding to the average value, and the instruction is sent to the PLC control unit; the PLC control unit generates a response control pulse after receiving the instruction, 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 stabilize the beam; otherwise, no subsequent processing is performed.

[0074] In summary, the present application determines the temperature difference coefficient at each acquisition moment based on the degree of difference between the temperature value of each sensor at each acquisition moment and its adjacent moments; by comparing the temperature differences at different time points, it is possible to more accurately analyze whether the temperature change is caused by unnatural factors; Furthermore, based on the frequency of occurrence of the temperature value at each collection moment and the similarity between the temperature value at each collection moment and the historical collection moment, the temperature anomaly coefficient at each collection moment is determined; by analyzing the similarity between each temperature value and the historical data, it is determined whether the change of the temperature value conforms to the change law caused by natural factors; Furthermore, the temperature difference coefficient and the temperature anomaly coefficient are combined to obtain the temperature anomaly coefficient at each acquisition time; reflecting the possibility that the temperature value at each acquisition time is caused by unnatural factors, and more comprehensively evaluating the cause of temperature change; Furthermore, based on the difference in the change trend of the temperature value between each acquisition moment and its neighboring acquisition moments, and combined with the difference in the discrete degree of the temperature value, the trend approximation value of each acquisition moment is determined; based on the difference in the temperature value between each sensor and all other sensors at each acquisition moment, and the difference in the temperature change speed between them, 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; through the difference between the temperature values ​​collected by different sensors at the same time, and combined with the change trend of the temperature value collected by the same sensor, the possibility of the temperature value collected by each sensor being caused by non-natural factors is analyzed, and the data of different sensors are combined for analysis, which can reduce misanalysis and improve the accuracy and reliability of the analysis results; Furthermore, based on the temperature anomaly coefficient and the difference factor, the avoidance adjustment value of each sensor at each acquisition moment is determined; based on the avoidance adjustment value, the temperature change threshold at each acquisition moment is determined; for temperature changes caused by non-natural factors, the temperature change threshold is not adjusted, and for temperature changes caused by natural factors, the temperature change threshold is adjusted, and then the magnetic field strength is adjusted according to the temperature change threshold, which solves 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.

[0075] The flowchart and block diagram in the accompanying drawings show the possible architecture, function and operation of the system, method and computer program product according to the embodiment of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowchart and the block diagram in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in a different order from the order disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified functions or actions, or may be implemented by a combination of dedicated hardware and computer instructions.

[0076] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the basic features of the present application. Therefore, no matter from which point of view, the above embodiments of the present application should be regarded as exemplary and non-restrictive.

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; Based on the frequency of occurrence of temperature values ​​at each collection moment and the similarity of temperature values ​​between each collection moment and historical collection moments, the temperature anomaly coefficient at each collection moment is determined; 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; 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 2, characterized in that: The determination process of the temperature anomaly coefficient is: 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; In the adjacent days of each collection time, a temperature value sequence at the same time as the temperature value sequence at each collection time is obtained, which is recorded as the second sequence; Calculating the distance between the first sequence and the second sequence; The temperature anomaly coefficient is proportional to the distance and inversely proportional to the occurrence frequency.

5. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 4, characterized in that: 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.

6. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 4, characterized in that: 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 degree of discreteness of the temperature value sequence between the ith acquisition moment and its adjacent moments; exp() is an exponential function with a natural constant as the base; α is a preset value greater than 0.

7. 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.

8. 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.

9. The method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation according to 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.

10. A method for adjusting the magnetic field strength of a medical cyclotron based on temperature compensation as claimed in claim 9, 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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