A method and system for measuring current through an electrometer of a radiation monitor

Abstract

The present application relates to the field of intelligent sensor technology, and specifically to a method and system for measuring current through an electrometer of a radiation monitor, the method comprising: obtaining a pulse current signal of an electrometer in a radiation environment, dividing the pulse current sequence into pulse periods, obtaining the overshoot reaction degree in each pulse period according to the difference between each maximum value and the maximum value of the current in each pulse period, and the rate of change between adjacent maximum values ​​and minimum values ​​in the current value of each pulse period, and obtaining the ringing fluctuation deviation of each pulse period in combination with the degree of current fluctuation when ringing occurs in each pulse period, obtaining the distortion coefficient of each pulse period, analyzing the current change distribution of multiple sampling moments that are closest to the time interval of each sampling moment, and then obtaining an adaptive search window at each sampling moment, and filtering the pulse current to obtain the electrometer current measurement result. The present application can realize the accurate measurement of the electrometer current in the radiation environment.

Description

Technical Field

[0001] The present application relates to the technical field of intelligent sensors, and in particular to a method and system for measuring current through an electrometer of a radiation monitor. Background Art

[0002] Radiation monitor is an instrument that uses sensors to measure and monitor radiation dose. It is widely used in nuclear energy, medical and environmental monitoring and can monitor various radiation source signals more accurately. Electrometer is a general term for a device that converts the detected radiation into proportional current. This solution is mainly aimed at the new compound semiconductor smart sensor of cadmium zinc telluride (CdZnTe, CZT). Due to the characteristics of wide bandgap, high sensitivity and high resistivity, CZT can be used for X / γ-ray detection.

[0003] Workers and technicians in radiation environments, such as radiation medical staff, radiation environment monitoring technicians, etc., may suffer adverse effects on their health due to long-term exposure to radiation. When the radiation source periodically emits radiation signals, the radiation signals are detected by CZT, and the CZT sensor will output fast pulse analog signals. Due to the fast response, overshoot and ringing will appear in the signal, causing the output current signal to be distorted, affecting the monitoring of the actual radiation amount.

[0004] For the collected distorted current signal, a collaborative filtering denoising algorithm is usually used, which mainly uses the self-similar characteristics of the signal to achieve noise reduction of the distorted signal. Usually, in the collaborative filtering denoising algorithm, it is necessary to determine the hyperparameter search window length. The size of the window length will determine the quality of the distorted signal noise reduction. In the traditional algorithm, the parameter value range is given by empirical values, and the optimal value is selected through continuous debugging. On the one hand, the parameter range given by the empirical value is not necessarily suitable for the fast pulse analog distortion signal output by the CZT sensor. On the other hand, the amount of calculation in the continuous adjustment and optimization process is large, which exceeds the processing capacity of the watch chip. It is necessary to quickly determine the hyperparameter based on the output fast pulse analog distortion signal. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of this application is to provide a method and system for measuring current through an electrometer of a radiation monitor. The technical solutions adopted are as follows:

[0006] The present application embodiment provides a method for measuring current by an electrometer of a radiation monitor, comprising the following steps:

[0007] Obtain the pulse current signal of the electrometer in the radiation environment, and the current at each sampling moment constitutes a pulse current sequence;

[0008] The pulse current sequence is divided into pulse periods based on each peak point in the pulse current sequence, the oscillation attenuation of each pulse period is determined according to the difference between each maximum value and the maximum value of the current in each pulse period, and the overshoot rate of each pulse period is calculated according to the change rate between adjacent maximum values ​​and minimum values ​​in the current value of each pulse period;

[0009] Combining the oscillation attenuation and the overshoot rate to obtain the overshoot reaction degree in each pulse cycle;

[0010] According to the fluctuation degree of the current when the ringing occurs in each pulse period, the ringing fluctuation deviation of each pulse period is obtained, and combined with the overshoot reaction degree, the distortion coefficient of each pulse period is obtained;

[0011] The current change distribution of multiple sampling moments with the closest time interval to each sampling moment is analyzed, and the distortion coefficient of the pulse period at each sampling moment is combined to obtain the adaptive search window at each sampling moment. The pulse current is filtered using a filtering algorithm to obtain the electrometer current measurement result.

[0012] Preferably, the division of the pulse period further includes: taking the smallest current value in a plurality of sampling moments before each peak value in the pulse current sequence as a division point, and determining the time interval between two adjacent division points as each pulse period.

[0013] Preferably, the calculation formula for the oscillation attenuation degree of each pulse period is:

[0014] Among them, B represents the oscillation attenuation degree of the current pulse cycle, N mam Indicates the number of current maximum values ​​in the current pulse cycle, I max and They represent the maximum current value and the i-th current maximum value in the current pulse cycle, Δt i Represents the time interval between the i-th current maximum value and the maximum current value.

[0015] Preferably, the calculation formula for the overshoot rate of each pulse period is:

[0016] In the formula, C represents the overshoot rate of the current pulse cycle, N represents the number of pairs of extreme values ​​composed of adjacent minimum and maximum values ​​in the current data in the current pulse cycle, and Respectively represent the maximum and minimum values ​​in the jth extreme value pair, Δt j Represents the time interval between the two extreme values ​​in the jth extreme value pair.

[0017] Preferably, the overshoot reaction degree in each pulse period is further a sum of the oscillation attenuation degree and the overshoot rate.

[0018] Preferably, the ringing fluctuation deviation of each pulse period includes:

[0019] Where D represents the ringing fluctuation deviation of the current pulse period, μ Δdis It represents the average value of the Euclidean distance from the current to the frontier growth line at each sampling moment in the frontier interval of the current pulse cycle, and ε represents the goodness of fit of the frontier growth line. The interval between the start of the pulse cycle and the current peak point within the pulse cycle is taken as the frontier interval, and the current in the frontier interval is fitted to obtain the frontier growth line.

[0020] Preferably, the distortion coefficient of each pulse period is the sum of the overshoot responsiveness and the ringing fluctuation deviation.

[0021] Preferably, the adaptive search window corresponding to each sampling moment is calculated as follows:

[0022] W i =W min +ΔW×norm(η i ×E); where W i represents the adaptive search window size at the i-th sampling time, W min represents the preset minimum search window size, ΔW represents the preset quantization window length, norm is the normalization function, η i It represents the coefficient of variation of the current at multiple sampling moments that are closest to the time interval of the i-th sampling moment, and E represents the distortion coefficient of the pulse period at the current sampling moment.

[0023] Preferably, the use of a filtering algorithm to filter the pulse current to obtain an electrometer current measurement result includes: using the current in a preset time period before each sampling moment as an input to a collaborative filtering denoising algorithm, the size of the search window during the filtering process is an adaptive search window size at each sampling moment, and outputting the noise-reduced current as the electrometer current measurement result.

[0024] An embodiment of the present application also provides a system for measuring current through an electrometer of a radiation monitor, the system comprising a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the steps of any one of the above methods when executing the computer program.

[0025] From the above, it can be seen that the method and system for measuring current by using an electrometer of a radiation monitor provided by the present application have at least the following beneficial effects:

[0026] This application uses CZT smart sensors to collect pulse current signals in a radiation environment, constructs an overshoot reaction degree based on the attenuation characteristics of the signal, reflects the degree of interference caused by the overshoot phenomenon in a single pulse cycle, and obtains the ringing fluctuation deviation based on the leading edge change characteristics of the pulse current signal, reflects the deviation of the pulse current caused by the ringing phenomenon, thereby obtaining the distortion coefficient, and finally obtains the adaptive window size according to the local characteristics of the current at each sampling moment. Compared with the fixed search window of the traditional collaborative filtering denoising algorithm, this application focuses on analyzing the impact of overshoot and ringing phenomena on pulse current, and constructs an adaptive search window size based on this, while improving the accuracy of the correction of the distorted signal, retaining the detailed information of the pulse current signal as much as possible, and realizing accurate measurement of the electrometer current. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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.

[0028] Figure 1 A flow chart of the steps of a method for measuring current by an electrometer of a radiation monitor provided in the present application;

[0029] Figure 2 Schematic diagram of the CZT sensing circuit provided for this application. DETAILED DESCRIPTION

[0030] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following, in combination with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features and effects of a method and system for measuring current through an electrometer of a radiation monitor proposed in the present application. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0031] Unless otherwise specified and limited, terms such as "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a circuit structure, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such articles or devices. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the article or device including the element. In addition, the term "and\or" used herein includes any and all combinations of one or more related listed items. All technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application.

[0032] The following is a detailed description of a method and system for measuring current through an electrometer of a radiation monitor provided by the present application in conjunction with the accompanying drawings.

[0033] See also Figure 1 , which shows a flowchart of a method for measuring current by an electrometer of a radiation monitor provided by an embodiment of the present application, including the following steps:

[0034] Step 1: Obtain the pulse current signal of the electrometer in the radiation environment. The current at each sampling moment constitutes a pulse current sequence.

[0035] In order to obtain radiation information in a radiation environment, the radiation environment set in this embodiment is an operating room corresponding to a radiotherapy room in a hospital scene. The specific CZT sensor circuit diagram is as follows: Figure 2 As shown, Figure 2 In the figure, number 1 indicates a CZT semiconductor sensor, number 2 indicates GED grounding, number 3 indicates that the power supply device of the device is a 5V DC power supply, number 4 indicates a resistor in the circuit, and the resistor is set to 10KΩ in this embodiment, number 5 indicates a capacitor in the circuit, and the capacitor is set to 5μF in this embodiment, number 6 indicates holes in the CZT semiconductor, number 7 indicates electrons in the semiconductor in the CZT, and OUT is the output terminal.

[0036] When the radioactive rays in the radiotherapy room pass through the wall and reach the CZT sensing interface and are detected, the rays act on the holes and electrons in the CZT semiconductor sensor, causing the holes and electrons to move to the cathode and anode respectively, thereby generating a pulsed induced current signal, which is detected by the current sensor at the OUT end.

[0037] Among them, since the frequency of pulse induced current signals generated by the rays acting on the holes and electrons of the CZT semiconductor is relatively fast, the frequency of the current sensor at the OUT end of the CZT sensor is set to 1GHZ in this embodiment, and the pulse current signal of the radiation is continuously collected during the operation in the radiotherapy room. Since the frequency of the CZT sensor output collection signal is relatively high, the amount of collected data is relatively large, which is not conducive to computer analysis. In this embodiment, the sampling interval is 1s. In this embodiment, the current values ​​at each sampling moment are arranged in chronological order to obtain a pulse current sequence.

[0038] Step 2: Divide the pulse current sequence into pulse periods based on the peak points in the pulse current sequence, determine the oscillation attenuation of each pulse period according to the difference between the maximum and maximum values ​​of the current in each pulse period, and calculate the overshoot rate of each pulse period according to the rate of change between adjacent maximum and minimum values ​​in the current value of each pulse period.

[0039] In the collaborative filtering denoising algorithm, the search window length determines the length of the data used for matching. If the search window is too small, it may result in smaller data blocks matching the same data distribution, resulting in poor data denoising effect. On the contrary, if the search window is too long, it may result in matching more dissimilar data blocks, resulting in loss of data details and over-smoothing, thereby reducing the denoising quality.

[0040] When a patient is given radiotherapy in a radiotherapy room, a radiation source is used to generate radiation rays, which are diffusely scattered through the radiotherapy room in the form of a beam. When the rays are detected by the CZT sensor, the incident photon beam of the rays generates charge deposition, transport and induction inside the CZT, thereby generating a pulse current signal. Since the pulse current signal is generated at a fast speed and the intensity of the current signal is small, the pulse current sequence collected at the output end by the CZT sensor circuit is prone to signal distortion caused by factors such as overshoot and ringing, resulting in deviations in the measurement of the specific radiation environment.

[0041] When the X-ray photon beam couples with the hole-electron pairs in the CZT sensor, a strong pulse current is generated. Then, when the X-ray photon beam decreases, the pulse current gradually decays. Under normal circumstances, it decays exponentially to zero. However, due to the existence of the overshoot phenomenon, the decay process of the pulse current is an oscillating decay, which will produce a certain amount of overshoot (bump) and undershoot (pit), causing the falling edge of the pulse current to be greatly distorted, which can easily interfere with the final measurement of the radiation environment.

[0042] In an ideal case, in a pulse current sequence, the data is expressed as follows: when the scattered ray photon beam is detected by the sensor, a peak current will be formed in a very short time. Since the ray photon beam is diffusely reflected in the radiation space, the pulse current signal slowly decays from the peak current exponentially to the lowest value between two adjacent ray photon beams. When the next ray photon beam arrives, a peak current will be formed again. If the overshoot phenomenon is used due to circuit factors, when the pulse current signal decays from the peak oscillation, the closer to the peak, the larger the oscillation amplitude, and the farther from the peak, the lower the oscillation amplitude. In addition, if the overshoot effect is more serious, the oscillation rate of the pulse peak current signal will be faster when it decays, and if the overshoot effect is slightly lighter, the oscillation rate will be slower.

[0043] In this embodiment, in order to facilitate the analysis of pulse current, the time interval between two adjacent pulses is defined as a pulse period. The pulse period in this embodiment is obtained by using the AMPD peak detection algorithm to output all peak values ​​in the pulse current sequence (the peak value is the peak current generated by the CZT sensor when it is affected by the photon beam of the radiation), and the minimum current value in the Q sampling moments before each peak value is used as a dividing point. In this embodiment, Q = 100. It should be noted that the data within 1 minute of the initial collection is not analyzed.

[0044] Therefore, according to the above method of this embodiment, several segmentation points of the pulse current sequence can be obtained. In this embodiment, the time interval between adjacent segmentation points is defined as the pulse period.

[0045] Furthermore, by performing extreme point detection on the pulse current signal within the pulse cycle, the extreme points therein are obtained, and the oscillation attenuation degree is calculated based on the difference between each maximum value and the maximum value of the current within each pulse cycle to reflect the oscillation attenuation of the sequence within the pulse cycle. In this embodiment, taking the current pulse cycle as an example, the specific calculation formula is:

[0046] Among them, B represents the oscillation attenuation degree of the current pulse cycle, N mam Indicates the number of current maximum values ​​in the current pulse cycle, I max and They represent the maximum current value and the i-th current maximum value in the current pulse cycle, Δt i Represents the time interval between the i-th current maximum value and the maximum current value.

[0047] When overshoot distortion occurs in the current pulse cycle, oscillation attenuation will occur after the current signal reaches the peak value. There will be more extreme points in each current of the current pulse cycle, among which each maximum value corresponds to the upshoot during overshoot, and each minimum value corresponds to the downshoot during overshoot. The farther from the peak value, that is, the longer the time interval, the greater the attenuation amplitude, and thus the greater the oscillation attenuation degree of the current pulse cycle.

[0048] Furthermore, in this embodiment, each minimum value of the current in the current pulse cycle and its adjacent subsequent maximum value are used to construct an extreme value pair, and the overshoot rate of each pulse cycle is calculated according to the change rate between the adjacent maximum value and the minimum value in the current value of each pulse cycle. The overshoot rate reflects the speed of the oscillation rate of the current in the pulse cycle when it is subjected to overshoot oscillation. The specific calculation formula is:

[0049] In the formula, C represents the overshoot rate of the current pulse cycle, N represents the number of pairs of extreme values ​​composed of adjacent minimum and maximum values ​​in the current data in the current pulse cycle, and Respectively represent the maximum and minimum values ​​in the jth extreme value pair, Δt j Represents the time interval between the two extreme values ​​in the jth extreme value pair.

[0050] If the pulse current sequence in the current pulse cycle is seriously affected by overshoot distortion, the faster the rate of overshoot oscillation is, the shorter the time interval between two adjacent extreme points is, and the greater the amplitude difference between adjacent extreme points is, the greater the overshoot rate of the pulse cycle is.

[0051] Step 3: Combining the oscillation attenuation and the overshoot rate to obtain the overshoot reaction degree in each pulse cycle.

[0052] Further, according to the above process of this embodiment, the oscillation attenuation degree of each pulse period can be obtained, and the overshoot rate in each pulse period can be analyzed. Based on this, the overshoot reaction degree in each pulse period is constructed to reflect the degree to which the pulse response in each pulse period is affected by the overshoot phenomenon. The specific expression is:

[0053] A=B+C; wherein A represents the overshoot reaction degree in the current pulse cycle.

[0054] When the overshoot phenomenon causes the pulse current sequence to be distorted, an oscillation attenuation will occur after the peak current in the sequence. At this time, more extreme values ​​will be generated, and the farther away from the extreme value, the more attenuation there is, so the value of the oscillation attenuation degree is larger. In addition, if the sequence is more seriously affected by the overshoot, the larger the amplitude and rate of the oscillation, the larger the value of the overshoot rate, and finally the value of the overshoot reaction degree is larger. On the contrary, if the current pulse cycle is not disturbed by the overshoot, the pulse current signal decays smoothly at this time, the number of maximum values ​​in the sequence is small, and the oscillation amplitude and rate between adjacent extreme values ​​are small, so the value of the overshoot reaction degree is small.

[0055] Step 4: The ringing fluctuation deviation of each pulse period is obtained according to the fluctuation degree of the current when the ringing occurs in each pulse period, and the distortion coefficient of each pulse period is obtained in combination with the overshoot reaction degree.

[0056] Affected by the impurities inside the CZT sensor or the angle of incident radiation, the pulse current signal will produce signal distortion due to the ringing phenomenon. Different from the distortion caused by the overshoot phenomenon, the overshoot phenomenon mainly acts on the trailing edge of the pulse signal, that is, after the peak value, while the ringing phenomenon mainly acts on the leading edge of the pulse current signal, resulting in multiple reflections, which results in several extreme points in the data that are close to the peak value, affecting the analysis of the pulse current signal.

[0057] The pulse current signal output by the CZT sensor may be interfered by any one or both of the phenomena (overshoot and ringing) at the same time. In order to measure the interference of the pulse current signal, the data characteristics of the ringing phenomenon are further analyzed in this embodiment.

[0058] When ringing occurs in the pulse cycle, the current peak value in the pulse cycle is used as the dividing point, and the interval from the beginning of the pulse cycle to the peak point is the frontier interval, that is, the interval from the beginning of the pulse cycle to the current peak point in the pulse cycle is used as the frontier interval. Ideally, the frontier stage, that is, in the frontier interval, is a line segment that rises rapidly under the influence of the ray photon beam. However, if it is affected by the ringing phenomenon, there will be more data noise points in the frontier interval, and a maximum point that is highly close to the peak value will appear.

[0059] Based on the above analysis, the pulse current in the frontier interval is fitted. In this embodiment, the least squares method is used to fit the frontier growth line. Further, the ringing fluctuation deviation of each pulse period is obtained according to the fluctuation degree of the current when the ringing occurs in each pulse period. The expression in this embodiment is:

[0060] Where D represents the ringing fluctuation deviation of the current pulse period, μ ΔdisIt represents the average value of the Euclidean distance from the current to the frontier growth line at each sampling moment in the frontier interval of the current pulse cycle, and ε represents the goodness of fit of the frontier growth line.

[0061] If the pulse current in the current pulse cycle is distorted due to the ringing phenomenon, there will be more noise points in the frontier interval, and extreme points close to the peak value will appear. At this time, the smaller the goodness of fit when linear fitting is performed on the pulse current signal in the frontier interval, and the greater the distance between the current value at the sampling moment and the frontier growth line, the greater the ringing fluctuation deviation will be.

[0062] Therefore, in this embodiment, the ringing fluctuation deviation of each pulse period is obtained according to the fluctuation degree of the current when the ringing occurs in each pulse period, and the distortion of the current in the current pulse period is comprehensively measured in combination with the overshoot reaction degree to obtain the distortion coefficient E of the current pulse period. The expression in this embodiment is:

[0063] E=A+D; where E represents the distortion coefficient of the current pulse period.

[0064] It can be understood that if the pulse current signal is less disturbed in the current pulse cycle, that is, there is no interference from overshoot and ringing, the obtained pulse current sequence shows a linear growth trend at the peak front edge and an exponential decay smoothing state at the trailing edge stage, thereby obtaining a smaller distortion coefficient in the pulse cycle. On the contrary, if the sequence is more seriously disturbed by overshoot and ringing in the current pulse cycle, the distortion coefficient obtained at this time is more serious, and the strength of data correction is greater.

[0065] Step 5: Analyze the current change distribution of multiple sampling moments that are closest to each sampling moment, and combine the distortion coefficient of the pulse period at each sampling moment to obtain the adaptive search window at each sampling moment, and use the filtering algorithm to filter the pulse current to obtain the electrometer current measurement result.

[0066] The distortion coefficient reflects the degree of overall interference of the pulse current in the current pulse cycle. Therefore, when correcting the current value at each sampling moment, it is necessary to analyze the situation at each sampling moment.

[0067] To further ensure the current measurement accuracy of the electrometer, in this embodiment, the local current distribution at each sampling moment is analyzed according to the current change fluctuation at the local neighboring moments of each sampling moment. Furthermore, based on the current distribution at the local neighboring moments of each sampling moment within the pulse period, combined with the distortion coefficient of the pulse period at each sampling moment, an adaptive search window at each sampling moment is constructed. The corresponding calculation formula is:

[0068] W i =W min +ΔW×norm(ηi ×E); where W i represents the adaptive search window size at the i-th sampling time, W min represents the preset minimum search window size, which is set to 100 in this embodiment, ΔW represents the preset quantization window length, which is determined by the maximum and minimum search window values. The maximum search window value in this embodiment is set to 500, so ΔW=400. It should be noted that the minimum search window size and the quantization window length are both used to limit the size range of the adaptive search window, which is set by the implementer according to the actual reference scenario. norm is a normalization function, and η i The coefficient of variation of the current at multiple sampling moments closest to the time interval of the i-th sampling moment is used to characterize the current change distribution at the local neighboring sampling moments of the i-th sampling moment, that is, the degree of fluctuation of the current data. In this embodiment, the coefficient of variation of the current at the 50 sampling moments closest to the time interval of each sampling moment is analyzed, and E represents the distortion coefficient of the pulse period at the current sampling moment.

[0069] If the overall signal is more seriously affected by overshoot and ringing in the current pulse period, the distortion coefficient will be larger. If the coefficient of variation of the pulse current at the local neighboring moments of each sampling moment in the pulse period is larger, it means that the current fluctuation is larger. At this time, a larger search window is needed to improve the noise reduction effect of the data. On the contrary, if the distortion coefficient within the overall pulse period is smaller, a smaller search window is used to retain the detailed information of the pulse signal.

[0070] So far, according to the above process of this embodiment, the adaptive search window at each sampling moment can be obtained, which is used to set the search window in the pulse current filtering process. In this embodiment, the current corresponding to 1 minute before each sampling moment is used as the input of the collaborative filtering denoising algorithm, wherein the size of the search window in the filtering process is the adaptive search window size, and the current after noise reduction is obtained after filtering processing as the accurate measurement result of the electrometer current. In this way, the measurement of the electrometer current signal constructed using the CZT sensor is realized.

[0071] Based on the same inventive concept as the above method, an embodiment of the present application also provides a system for measuring current through an electrometer of a radiation monitor, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above methods for measuring current through an electrometer of a radiation monitor are implemented.

[0072] It is to be understood that the sequence of the embodiments of the present application described above is for description only and does not represent the advantages and disadvantages of the embodiments. The above describes specific embodiments of the present specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0073] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0074] The above content is only an implementation method of the present application and is not intended to limit the scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the protection scope of the present application.

Claims

1. A method for measuring current by an electrometer of a radiation monitor, characterized in that: The following steps are involved: Obtain the pulse current signal of the electrometer in the radiation environment, and the current at each sampling moment constitutes a pulse current sequence; The pulse current sequence is divided into pulse periods based on each peak point in the pulse current sequence, the oscillation attenuation of each pulse period is determined according to the difference between each maximum value and the maximum value of the current in each pulse period, and the overshoot rate of each pulse period is calculated according to the change rate between adjacent maximum values ​​and minimum values ​​in the current value of each pulse period; Combining the oscillation attenuation and the overshoot rate to obtain the overshoot reaction degree in each pulse cycle; The ringing fluctuation deviation of each pulse period is obtained according to the fluctuation degree of the current when the ringing occurs in each pulse period, and the distortion coefficient of each pulse period is obtained in combination with the overshoot reaction degree; The current change distribution of multiple sampling moments with the closest time interval to each sampling moment is analyzed, and the distortion coefficient of the pulse period at each sampling moment is combined to obtain the adaptive search window at each sampling moment. The pulse current is filtered using a filtering algorithm to obtain the electrometer current measurement result.

2. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The division of the pulse period further includes: taking the smallest current value in a plurality of sampling moments before each peak value in the pulse current sequence as a division point, and determining the time interval between two adjacent division points as each pulse period.

3. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The calculation formula of the oscillation attenuation degree of each pulse period is: Among them, B represents the oscillation attenuation degree of the current pulse cycle, N mam Indicates the number of current maximum values ​​in the current pulse cycle, I max and They represent the maximum current value and the i-th current maximum value in the current pulse cycle, Δt i Represents the time interval between the i-th current maximum value and the maximum current value.

4. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The calculation formula for the overshoot rate of each pulse cycle is: In the formula, C represents the overshoot rate of the current pulse cycle, N represents the number of pairs of extreme values ​​composed of adjacent minimum and maximum values ​​in the current data in the current pulse cycle, and Respectively represent the maximum and minimum values ​​in the jth extreme value pair, Δt j Represents the time interval between the two extreme values ​​in the jth extreme value pair.

5. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The overshoot reaction degree in each pulse period is further a sum of the oscillation attenuation degree and the overshoot rate.

6. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The ringing fluctuation deviation of each pulse period includes: Where D represents the ringing fluctuation deviation of the current pulse period, μ Δdis It represents the average value of the Euclidean distance from the current to the frontier growth line at each sampling moment in the frontier interval of the current pulse cycle, and ε represents the goodness of fit of the frontier growth line. The interval between the start of the pulse cycle and the current peak point within the pulse cycle is taken as the frontier interval, and the current in the frontier interval is fitted to obtain the frontier growth line.

7. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The distortion coefficient of each pulse period is the sum of the overshoot reaction degree and the ringing fluctuation deviation.

8. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The corresponding calculation process of the adaptive search window at each sampling time is: W i =W min +ΔW×norm(η i ×E); where W i represents the adaptive search window size at the i-th sampling time, W min represents the preset minimum search window size, ΔW represents the preset quantization window length, norm is the normalization function, η i It represents the coefficient of variation of the current at multiple sampling moments that are closest to the time interval of the i-th sampling moment, and E represents the distortion coefficient of the pulse period at the current sampling moment.

9. A method for measuring current by an electrometer of a radiation monitor as claimed in claim 1, characterized in that: The method of filtering the pulse current using a filtering algorithm to obtain the electrometer current measurement result includes: using the current in a preset time period before each sampling moment as the input of a collaborative filtering denoising algorithm, the size of the search window during the filtering process is the adaptive search window size of each sampling moment, and outputting the noise-reduced current as the electrometer current measurement result.

10. A system for measuring current by an electrometer of a radiation monitor, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 9 are implemented.

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