A method for self-starting the high-frequency system of a medical cyclotron

Abstract

This application relates to the field of high-frequency control technology for cyclotrons, and specifically relates to a method for self-starting the high-frequency system of a medical cyclotron. The method includes: classifying the output voltage and cavity voltage of the medical cyclotron at all times within a preset time period respectively, and obtaining the matching degree between the output voltage and the cavity voltage according to the difference between the output voltage and the cavity voltage categories; optimizing the matching degree based on the change of the cavity phase to obtain the resonance degree between the output voltage and the cavity voltage; obtaining the temperature influence factor according to the cavity temperature data within the time period corresponding to the resonance degree; and adjusting the output frequency during the self-starting process of the medical cyclotron based on the temperature influence factor and the resonance degree. This application aims to regulate the output frequency during the self-starting process of the high-frequency system, reduce the possibility of detuning of the high-frequency system of the medical cyclotron, and improve the overall stability of the high-frequency system.

Description

Technical Field

[0001] This application relates to the technical field of high-frequency control of cyclotrons, and particularly to a method for self-starting the high-frequency system of a medical cyclotron. Background Art

[0002] The high-frequency system of a medical cyclotron is a key system that provides energy for the accelerator. Generally, it consists of a low-level control system, a transmitter and amplifier system, and a radio frequency resonator cavity, etc. Its task is to provide the high-frequency voltage necessary for ion cyclotron acceleration. The high-frequency voltage is applied to the high-frequency cavity to achieve particle acceleration.

[0003] During the actual start-up process of the cyclotron, due to the influence of factors such as beam load, gravity, and heat loss, the shape of the cavity will change, and then the resonant frequency of the cavity will shift. If the system is out of tune during self-starting, it may cause the frequency locker to fail to correctly lock to the desired frequency, requiring additional time for adjustment and calibration, prolonging the entire self-starting process and affecting the overall stability of the high-frequency system. Summary of the Invention

[0004] In view of the above, it is necessary to provide a method for self-starting the high-frequency system of a medical cyclotron to solve the above problems.

[0005] An embodiment of this application provides a method for self-starting the high-frequency system of a medical cyclotron, and the method includes:

[0006] Obtain the output voltage, output frequency of the power source of the medical cyclotron, the cavity voltage, cavity phase, and cavity temperature within a preset time period;

[0007] Classify the output voltage and cavity voltage at all times respectively, and obtain the matching degree between the output voltage and the cavity voltage according to the difference between the output voltage and the cavity voltage category;

[0008] Optimize the matching degree based on the change of the cavity phase to obtain the resonance degree between the output voltage and the cavity voltage;

[0009] Obtain the temperature influence factor according to the cavity temperature during the time period corresponding to the resonance degree; adjust the output frequency during the self-starting process of the medical cyclotron based on the temperature influence factor and the resonance degree.

[0010] Among them, the step of classifying the output voltage and cavity voltage at all times respectively includes:

[0011] After normalizing the output voltages at all times, clustering is performed. The category with the highest average level of the normalized values of all output voltage data in the obtained clustering clusters is taken as the first category of output voltage, and the remaining clustering clusters are taken as the second category of output voltage; the same method is used for the cavity voltage to obtain the first category of cavity voltage and the second category of cavity voltage.

[0012] Among them, the specific process of obtaining the matching degree between the output voltage and the cavity voltage is as follows:

[0013] The cavity voltage closest to each output voltage moment in the first category of cavity voltage is recorded as the neighboring cavity voltage of each output voltage.

[0014] According to the distribution difference between the output voltage and its neighboring cavity voltage, the matching factor between the output voltage and its neighboring cavity voltage is obtained.

[0015] The result after fusing all the matching factors in the first category of output voltage is used as the numerator of the matching degree between the output voltage and the cavity voltage; the difference in the average level between all the output voltages in the second category of output voltage and all the cavity voltages in the second category of cavity voltage is used as the denominator of the matching degree.

[0016] Among them, the steps for obtaining the matching factor between the output voltage and its neighboring cavity voltage are as follows:

[0017] The maximum value and the absolute value of the difference between each output voltage in the first category of output voltage and its neighboring cavity voltage are obtained respectively; based on the inverse proportional mapping result of the absolute value of the difference and the maximum value, the matching factor between each output voltage in the first category of output voltage and its neighboring cavity voltage is obtained.

[0018] Among them, the specific method for obtaining the resonance degree between the output voltage and the cavity voltage is as follows:

[0019] According to the fluctuation characteristics of the cavity voltage, the period length of the cavity voltage is obtained; the period length of the cavity voltage is used as the actual period length of the cavity phase.

[0020] Based on the actual period length of the cavity voltage, the cavity phase is segmented, and the change degree of the cavity phase is obtained through the difference of the cavity phase in different periods.

[0021] The ratio of the matching degree to the change degree of the cavity phase is used as the resonance degree between the output voltage and the cavity voltage.

[0022] Among them, the process of obtaining the period length of the cavity voltage is specifically as follows:

[0023] Perform curve fitting on the cavity voltage, and extract all zeros of the fitted curve of the cavity voltage; take the time interval between adjacent zeros as the candidate period length; take the candidate period length with the highest frequency as the period length of the cavity voltage.

[0024] Among them, obtaining the cavity phase change degree is specifically as follows:

[0025] Obtain the number of periods after dividing the cavity phase; according to the similarity of the cavity phase distribution of any one period and the remaining periods, combined with the difference of the cavity phase, obtain the phase similarity degree between any one period and the remaining periods; obtain the inverse proportional mapping result of the maximum value of the phase similarity degree of any one period; fuse the inverse proportional mapping results of all periods to obtain the cavity phase change degree.

[0026] Among them, obtaining the temperature influence factor is specifically as follows:

[0027] Based on the cavity temperature during the time period corresponding to the resonance degree, obtain the normal temperature of the time period;

[0028] Obtain the resonance degree and the corresponding normal temperature of a preset number of historical time periods; arrange the resonance degrees in ascending order of the normal temperature, calculate the absolute value of the difference between the resonance degrees at adjacent positions, and take the cumulative sum of the absolute values of the differences as the temperature influence factor.

[0029] Among them, obtaining the normal temperature of the time period is specifically the cavity temperature with the highest frequency of occurrence during the time period corresponding to the resonance degree.

[0030] Among them, adjusting the output frequency during the self-starting process of the medical cyclotron is specifically as follows:

[0031] Take the normal temperature of the cavity with the highest frequency of occurrence in all time periods corresponding to the current time as the normal temperature of the cavity; if the temperature of the high-frequency resonant cavity of the medical cyclotron at the current moment is less than the normal temperature of the cavity at the current moment, ; if the temperature of the high-frequency resonant cavity of the medical cyclotron at the current moment is equal to the normal temperature of the cavity at the current moment, ; otherwise, ;

[0032] Among them, represents the output frequency of the high-frequency power source at the current moment; is the output frequency of the high-frequency power source after adjustment at the current moment; is a preset tuning parameter factor; represents the resonance degree at the current temperature; represents the temperature influence factor corresponding to the current moment; Norm() represents the normalization function.

[0033] The present application has at least the following beneficial effects:

[0034] The present application first obtains the relevant operating parameters of a medical cyclotron for a period of time, classifies them through the waveform characteristics of the output voltage and the cavity voltage, and obtains the matching degree. The beneficial effect is to measure the reflection characteristics during the transmission of the output voltage and the cavity voltage, and to reflect whether there is a power reflection phenomenon in the high-frequency system; at the same time, based on the periodicity of the output frequency of the cyclotron, the resonance degree is constructed. The beneficial effect is to reflect the resonance condition of the output voltage and the cavity voltage from the voltage change and phase change of the resonant cavity; based on the relationship between different temperatures and the resonance degree in historical data, a temperature influence factor is constructed. The beneficial effect is to measure the influence of temperature change on the resonance degree; by combining temperature change and resonance degree adaptively, the frequency regulation of the radio frequency signal is completed, reducing the possibility of detuning of the high-frequency system of the medical cyclotron, accelerating the self-starting process, and improving the overall stability of the high-frequency system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flowchart of a method for self-starting a high-frequency system of a medical cyclotron provided by the present application;

[0036] Figure 2 It is a flowchart for obtaining the resonance degree provided by the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" are used to indicate 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" is intended to present related concepts in a specific manner.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application.

[0039] In addition, it should be noted that the terms "first" and "second" in the present application and its drawings are used to distinguish similar objects, rather than to describe a specific order or sequence. For the method disclosed in the embodiments of the present application or the method shown in the flowchart, including one or more steps for implementing the method, without departing from the scope of protection of the present application, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0041] This application first proposes a self-starting method for the high-frequency system of a medical cyclotron, which is applied to the technical field of high-frequency self-starting of a cyclotron. Referring to the attached Figure 1 , the method includes the following steps:

[0042] S1: Obtain the output voltage and output frequency of the power source of the medical cyclotron, the cavity voltage, cavity phase, and cavity temperature of the resonant cavity within a preset time period.

[0043] The output voltage of the high-frequency power source is monitored through the control unit of the high-frequency generator in the medical cyclotron; the output frequency of the high-frequency power source is obtained through a frequency meter, the cavity voltage and cavity phase of the resonant cavity are obtained through a high-frequency voltage probe and a phase probe, and the cavity temperature of the resonant cavity is obtained by using a temperature sensor. In this embodiment, the acquisition time interval is 10 microseconds, and the preset time period is the current and the previous 5 minutes; the implementer can set it according to the actual situation.

[0044] Among them, the output voltage of the high-frequency generator is converted into an appropriate high-frequency signal through a high-frequency transmitter, and then transmitted to the high-frequency resonant cavity through a feeder line to excite the resonant cavity to work; the frequency is the output frequency of the high-frequency power source; the cavity voltage is the peak-to-peak value of the electric field strength inside the resonant cavity. At the resonant frequency, the cavity voltage usually reaches its maximum value. This is because the resonant cavity is designed by precisely adjusting its structural dimensions and material properties so that at a specific frequency, the electric field energy inside the cavity can be maximally accumulated and concentrated. The phase of the cavity voltage describes the variation of the electric field with time in the radio frequency field, usually expressed in degrees, which indicates how the waveform of the electric field wave changes over time. The cavity phase is obtained relative to the reference point of the driving radio frequency signal. The frequency of the resonant cavity is determined by the physical dimensions, shape, and dielectric properties inside the cavity. These factors jointly affect the natural frequency of the cavity, that is, in the absence of an external drive, the cavity will naturally resonate at a specific frequency.

[0045] S2: Classify the output voltage and cavity voltage at all times respectively, and obtain the matching degree between the output voltage and the cavity voltage according to the difference between the output voltage and the cavity voltage categories.

[0046] For a medical cyclotron, the accelerator needs to have a highly stable accelerating voltage at different frequencies. In order to make the high-frequency resonant cavity resonate at the selected center frequency, the tuning system is usually controlled. The main functions of the high-frequency tuning system include three aspects: First, to match the cavity with the power source; second, to ensure the open-loop stability of the cavity voltage; third, to reduce the factors causing phase drift of the cavity voltage signal. Usually, it is necessary to monitor the detuning condition of the high-frequency tuning system and then regulate the high-frequency power source.

[0047] The resonant frequency of a cyclotron usually depends on the size and design of the accelerator ring of the cyclotron, that is, the structure of the high-frequency cavity of the cyclotron corresponds to a basic resonant frequency (cavity frequency). However, during the actual startup process of the cyclotron, due to factors such as beam load, gravity, and cavity deformation caused by heat loss, its resonant frequency often undergoes a certain shift. At this time, when using the basic resonant frequency to control the high-frequency system, its working efficiency is relatively low.

[0048] By controlling the automatic tuning system, the output frequency of the high-frequency power source of the high-frequency system is matched with the cavity frequency of the high-frequency cavity.

[0049] First, analyze the output voltage of the high-frequency power source and the cavity voltage in the high-frequency system. The collected voltage data is time-series data. Since the cyclotron needs a stable electric field to accelerate particles, the output voltage of the high-frequency power source is usually a high-frequency alternating voltage signal, and the signal is a sine wave or an approximate sine wave, generally remaining stable without frequent waveform changes.

[0050] Classify the output voltage and the cavity voltage at all times respectively:

[0051] After normalizing the output voltage at all times and then performing clustering, the category with the largest average level of the normalized values of all output voltage data in the obtained clustering cluster is used as the first category of the output voltage, and the remaining categories are used as the second category of the output voltage; the same method is used for the cavity voltage to obtain the first category of the cavity voltage and the second category of the cavity voltage.

[0052] In this embodiment, the Z-score algorithm is used for the output voltage of the cyclotron to obtain the Z-score corresponding to the output voltage. The larger the Z-score, the greater the voltage fluctuation of the output voltage and the greater the possibility of being interfered. Then each output voltage has a corresponding Z-score.

[0053] In this embodiment, the K-means clustering algorithm is respectively used for the output voltage and the cavity voltage, where K is set to 2 and the distance metric is the absolute value of the difference in Z-scores, and the collected output voltage is segmented into two categories; in other embodiments, the clustering algorithm can be replaced with a threshold segmentation algorithm. Among them, the K-means clustering algorithm is a well-known existing technology, and this application will not elaborate on it. Implementers can also choose other clustering algorithms, and this application does not limit this.

[0054] In this embodiment, the average level of a set of data refers to the average value of a set of data, that is, the category with the largest average Z-score in the two categories is recorded as the first category of the output voltage, and the other category is recorded as the second category of the output voltage. Similarly, the first category of the cavity voltage and the second category of the cavity voltage are obtained; in other embodiments, the average value can be replaced with the mode.

[0055] According to the difference between the output voltage and the cavity voltage categories, the matching degree between the output voltage and the cavity voltage is obtained:

[0056] The cavity voltage in the first category of the cavity voltage that is closest to each output voltage moment in the first category of the output voltage is recorded as the neighboring cavity voltage of each output voltage; the maximum value and the absolute value of the difference between each output voltage in the first category of the output voltage and its neighboring cavity voltage are respectively obtained; based on the inverse proportional mapping result of the absolute value of the difference and the maximum value, the matching factor between each output voltage in the first category of the output voltage and its neighboring cavity voltage is obtained.

[0057] It should be noted that in this embodiment, the inverse proportional mapping result between variables is obtained by using the method of ratio.

[0058] In this embodiment, the formula form of the matching factor between the i-th output voltage in the first category of the output voltage and its neighboring cavity voltage is: , where represents the matching factor between the i-th output voltage in the first category of the output voltage and its neighboring cavity voltage, represents the Z-score of the i-th output voltage in the first category of the output voltage, represents the Z-score of the neighboring cavity voltage of the i-th output voltage in the first category of the output voltage, that is, the Z-score of the cavity voltage in the first category of the cavity voltage that is closest to the data point collection moment of the i-th data point in the first category of the output voltage, represents the maximum value function.

[0059] The result after fusing all the matching factors in the first category of the output voltage is used as the numerator of the matching degree between the output voltage and the cavity voltage; the difference in the average level between all the output voltages in the second category of the output voltage and all the cavity voltages in the second category of the cavity voltage is used as the denominator of the matching degree.

[0060] In this embodiment, the formula form of the matching degree between the output voltage and the cavity voltage is: , where represents the matching degree between the output voltage and the cavity voltage, represents the matching factor between the i-th output voltage in the first category of output voltages and its neighboring cavity voltage, represents the total number of output voltages in the first category of output voltages, represents the average value of the output voltages in the second category of output voltages, then represents the average value of the cavity voltages in the second category of cavity voltages; in other embodiments, can be replaced with ; in some other embodiments, the average value of the output voltage and the average value of the cavity voltage can be replaced with the median of the output voltage and the median of the cavity voltage respectively.

[0061] It should be noted that since there must be a certain loss in the process of the output voltage being transmitted to the resonant cavity during actual use, the difference between the average value of the cavity voltage and the average value of the output voltage in the second category cannot be 0.

[0062] Furthermore, it should be noted that for the output voltage and the cavity voltage, the matching degree between the output voltage and the cavity voltage is used to reflect whether there is a power reflection phenomenon in the current high-frequency system. The greater the matching degree, the smaller the possibility of power reflection in the high-frequency system due to frequency mismatch; the smaller the matching degree, the greater the possibility of power reflection in the high-frequency system, and the greater the impact of frequency mismatch.

[0063] It should be understood that if the matching degree between the output voltage and the cavity voltage is small, it means that the impedance mismatch between them may be large. In this case, part of the energy will not be effectively transmitted into the cavity but will be reflected back to the power source, resulting in an increase in reflection loss. These reflections will reduce the system efficiency and may cause instability or damage to the power source.

[0064] S3: Optimize the matching degree based on the change of the cavity phase to obtain the resonance degree between the output voltage and the cavity voltage.

[0065] A medical cyclotron is usually a type of radiofrequency accelerator. In an RF accelerator, the RF field oscillates at a certain frequency, which is usually fixed, i.e., the cavity frequency; when the particle beam passes through the accelerator, it must be synchronized with the phase of the RF field to obtain effective acceleration. Therefore, the phase change of the particle relative to the RF field is periodic with the frequency of the RF field.

[0066] For the collected cavity phase, first obtain its period. Since the frequency of the RF field usually remains consistent with the frequency of the cavity voltage, the period length of the cavity voltage data can be obtained as the actual period length of the cavity phase.

[0067] Perform curve fitting on the cavity voltage, and extract all the zeros of the cavity voltage fitting curve; take the time interval between adjacent zeros as the candidate period length; take the candidate period length with the highest frequency as the period length of the cavity voltage.

[0068] For the cavity voltage data, since it is a sine wave. In this embodiment, the least squares method is used to perform curve fitting on the cavity voltage, and the zeros of the cavity voltage fitting curve are obtained. The time interval between the acquisition times of the a-th zero and the (a + 1)-th zero is taken as the a-th candidate period length. Statistics are performed on all the obtained candidate period lengths, and the candidate period length with the highest frequency is taken as the actual period length of the cavity voltage.

[0069] Segment the cavity phase based on the actual period length of the cavity voltage, and obtain the cavity phase change degree through the difference in the cavity phase within different periods:

[0070] Obtain the number of periods after segmenting the cavity phase; according to the similarity of the cavity phase distribution between any one period and the remaining periods, combined with the difference of the cavity phase, obtain the phase similarity between any one period and the remaining periods; obtain the inverse proportional mapping result of the maximum value of the phase similarity of any one period; fuse the inverse proportional mapping results of all periods to obtain the cavity phase change degree.

[0071] In this embodiment, the phase similarity between two periods is specifically as follows: calculate the Pearson correlation coefficient of the phase data within the two periods; calculate the cumulative sum of the absolute values of the differences of all corresponding cavity phases, and take the ratio of the Pearson correlation coefficient to the cumulative sum as the phase similarity between the two periods; in order to avoid the denominator being zero, a preset value needs to be added to the denominator, and the value of the preset value in the embodiment is 0.01.

[0072] It should be understood that since the period lengths are the same, when calculating the phase similarity between two periods, their cavity phases can be in one-to-one correspondence, that is, the first cavity phase within a period corresponds to the first cavity phase within another period.

[0073] In this embodiment, the formula form of the cavity phase change degree is: , where represents the cavity phase change degree, K is the number of periods segmented, represents the maximum value of the phase similarity between the k-th period and the remaining periods, is a preset parameter greater than zero to prevent the denominator from being 0, and its value is 0.01.

[0074] Take the ratio of the matching degree to the cavity phase change degree as the resonance degree of the output voltage to the cavity voltage.

[0075] Among them, the flow chart for obtaining the resonance degree is as Figure 2 shown.

[0076] It should be understood that the resonance degree reflects the resonance condition of the output voltage and the cavity voltage from the voltage change and phase change of the resonant cavity.

[0077] S4: Obtain the temperature influence factor according to the cavity temperature data during the corresponding time period of the resonance degree; based on the temperature influence factor and the resonance degree, adjust the output frequency during the self-starting process of the medical cyclotron.

[0078] Since the cavity voltage is easily affected by the change of the cavity temperature during acquisition, and the change of the cavity temperature will directly affect the performance of electronic components, resulting in fluctuations and drifts in the signals of the high-frequency resonant cavity.

[0079] Obtain the temperature influence factor according to the cavity temperature data during the corresponding time period of the resonance degree:

[0080] Based on the cavity temperature during the corresponding time period of the resonance degree, obtain the normal temperature of the time period;

[0081] Obtain the resonance degree and the corresponding normal temperature of a preset number of historical time periods; arrange the resonance degrees in ascending order according to the normal temperature, calculate the absolute value of the difference between adjacent resonance degrees, and take the cumulative sum of the absolute values of the differences as the temperature influence factor;

[0082] In this embodiment, the preset number of historical time periods is specifically 15 historical time periods before the current preset time period; the time lengths of the historical time periods and the preset time period are equal; the implementer can adjust it by himself.

[0083] Based on the temperature influence factor, compare the cavity temperature of the current high-frequency resonant cavity with the normal cavity temperature of the medical accelerator, and adjust the frequency of the high-frequency power radio frequency signal:

[0084] The adjusted frequency formula is in the form of: , where T represents the temperature of the high-frequency resonant cavity of the medical cyclotron at the current moment; represents the normal cavity temperature of the medical cyclotron at the current moment; represents the output frequency of the high-frequency power source at the current moment; is the adjusted output frequency of the high-frequency power source at the current moment; is the preset tuning parameter factor; represents the resonance degree at the current temperature; Y represents the temperature influence factor corresponding to the current moment; Norm() represents the normalization function.

[0085] It should be noted that the normal temperature of the cavity of the medical cyclotron at the current moment is specifically the normal temperature with the highest frequency of occurrence in the current time period and the preset number of previous time periods.

[0086] In this embodiment, the parameter adjustment factor is set to 0.01 to limit the excessive one-time adjustment of the output frequency; the sigmoid function is selected as the normalization function; the implementer can adjust it according to the actual situation.

[0087] According to the above steps, the frequency control of the radio frequency signal of the high-frequency power source in the self-starting process of the high-frequency system of the medical cyclotron is completed, which improves the operation efficiency and accuracy of the high-frequency system of the medical cyclotron and reduces the harm to the equipment.

[0088] The embodiment of the present application provides a method for self-starting the high-frequency system of a medical cyclotron. The method includes: first, obtaining relevant operation parameters of the medical cyclotron for a period of time, classifying them through the waveform characteristics of the output voltage and the cavity voltage to obtain the matching degree, and its beneficial effect is to measure the reflection characteristics in the transmission process of the output voltage and the cavity voltage and reflect whether there is a power reflection phenomenon in the high-frequency system; at the same time, based on the periodicity of the output frequency of the cyclotron, the resonance degree is constructed, and its beneficial effect is to reflect the resonance condition of the output voltage and the cavity voltage from the voltage change and phase change of the resonant cavity; based on the relationship between different temperatures and the resonance degree in historical data, a temperature influence factor is constructed, and its beneficial effect is to measure the influence of temperature change on the resonance degree; combining the temperature change and the resonance degree to adaptively complete the frequency regulation of the radio frequency signal, reducing the possibility of detuning of the high-frequency system of the medical cyclotron, accelerating the self-starting process, and improving the overall stability of the high-frequency system.

[0089] 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 application. 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 that contains one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions noted in the blocks may occur in a different order than noted in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions 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, or they may sometimes be executed in reverse order, depending on the functions involved. Each block in the block diagram and / or flowchart, as well as combinations of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0090] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A self-starting method for the high-frequency system of a medical cyclotron, characterized in that, The method includes the following steps: Obtain the output voltage, output frequency of the medical cyclotron power source, cavity voltage, cavity phase, and cavity temperature within a preset time period; After normalizing the output voltages at all times, perform clustering. Take the category with the maximum average level of the normalized values of all output voltage data in the obtained clustering clusters as the first category of output voltage, and the remaining clustering clusters as the second category of output voltage; use the same method for the cavity voltage to obtain the first category of cavity voltage and the second category of cavity voltage; record the cavity voltage closest to each output voltage moment in the first category of cavity voltage as the neighboring cavity voltage of each output voltage; based on the distribution difference between the output voltage and its neighboring cavity voltage, obtain the matching factor between the output voltage and its neighboring cavity voltage. Based on all the matching factors corresponding to the first category of output voltage, and combining the distribution difference between the output voltage and the cavity voltage in the second category of output voltage and cavity voltage, obtain the matching degree between the output voltage and the cavity voltage; According to the fluctuation characteristics of the cavity voltage, obtain the period length of the cavity voltage; divide the cavity phase based on the period length of the cavity voltage, and through the difference in cavity phase within different periods, obtain the cavity phase change degree. Combine the matching degree to obtain the resonance degree between the output voltage and the cavity voltage; Obtain the resonance degrees and corresponding normal temperatures in a preset number of historical time periods; arrange the resonance degrees in ascending order of normal temperature, calculate the absolute value of the difference between adjacent resonance degrees, and take the cumulative sum of the absolute values of the differences as the temperature influence factor; based on the temperature influence factor and the resonance degrees, adjust the output frequency during the self-starting process of the medical cyclotron.

2. The self-starting method of a high-frequency system of a medical cyclotron according to claim 1, characterized in that, The specific process of obtaining the matching degree between the output voltage and the cavity voltage is as follows: Take the result of fusing all the matching factors in the first category of output voltage as the numerator of the matching degree between the output voltage and the cavity voltage; take the difference in the average level between all the output voltages in the second category of output voltage and all the cavity voltages in the second category of cavity voltage as the denominator of the matching degree.

3. The self-starting method of the high-frequency system of a medical cyclotron according to claim 1, characterized in that, The steps for obtaining the matching factor between the output voltage and its neighboring cavity voltage are as follows: Respectively obtain the maximum value and the absolute value of the difference between each output voltage in the first category of output voltage and its neighboring cavity voltage; based on the inverse proportional mapping result of the absolute value of the difference and the maximum value, obtain the matching factor between each output voltage in the first category of output voltage and its neighboring cavity voltage.

4. The self-starting method of a high-frequency system of a medical cyclotron according to claim 1, wherein, The specific process of obtaining the period length of the cavity voltage is as follows: Perform curve fitting on the cavity voltage, and extract all the zero points of the cavity voltage fitting curve; take the time interval between adjacent zero points as the candidate period length; take the candidate period length with the highest frequency of occurrence as the period length of the cavity voltage.

5. A self-starting method for a high-frequency system of a medical cyclotron according to claim 1, characterized in that The specific process of obtaining the cavity phase change degree is as follows: Obtain the number of periods after the cavity phase is segmented; according to the similarity of the cavity phase distribution of any one period and the remaining periods, combined with the difference of the cavity phase, obtain the phase similarity between the any one period and the remaining periods; obtain the inverse proportional mapping result of the maximum value of the phase similarity of the any one period; fuse the inverse proportional mapping results of all periods to obtain the cavity phase change degree.

6. The self-starting method of the high-frequency system of a medical cyclotron according to claim 1, characterized in that, The resonance degree of the output voltage and the cavity voltage is specifically the ratio of the matching degree to the cavity phase change degree.

7. A self-starting method for a high-frequency system of a medical cyclotron according to claim 1, characterized in that, The normal temperature of the obtained time period is specifically the cavity temperature with the highest frequency of occurrence within the time period corresponding to the resonance degree.

8. The self-starting method of a high-frequency system of a medical cyclotron according to claim 1, wherein The adjustment of the output frequency during the self-starting process of the medical cyclotron is specifically as follows: Take the normal temperature with the highest frequency of occurrence in all time periods corresponding to the current time as the cavity normal temperature; if the temperature of the high-frequency resonant cavity of the medical cyclotron at the current moment is less than the cavity normal temperature at the current moment, ; When the temperature of the high-frequency resonant cavity of the medical cyclotron at the current moment is equal to the normal temperature of the cavity at the current moment, ; Otherwise, ; Among them, represents the output frequency of the high-frequency power source at the current moment; is the output frequency of the high-frequency power source after adjustment at the current moment; is a preset parameter adjustment factor; represents the resonance degree at the current temperature; represents the temperature influence factor corresponding to the current moment; Norm() represents the normalization function.

Images