Rapid calibration test method and system for two-dimensional imaging detector

Abstract

The invention provides a rapid calibration test method and system for a two-dimensional imaging detector, and relates to the technical field of imaging detector performance testing, and the method comprises the steps: 1, enabling rays to rapidly cover a whole to-be-calibrated imaging region through adjusting the incident position of a radioactive source; 2, photon peak information is obtained from the pulse amplitude spectrum of each electronic channel, wide-range calibration is achieved, a calibration curve is given, and the linear performance of the system is evaluated; 3, evaluating the uniformity of the whole imaging system through multi-channel data analysis; in the debugging and calibration link of the two-dimensional imaging detector, a radiation source is used for generating an approximately uniform radiation field to cover the whole imaging area to be calibrated, then low-range signals and high-range signals of all photoelectric devices and electronics channels are obtained, and through data analysis and statistics, the calibration precision of the two-dimensional imaging detector is improved. And rapid wide-range calibration of the whole imaging system is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging detector performance testing, and in particular to a rapid calibration testing method and system for a two-dimensional imaging detector. Background Art

[0002] With the continuous development of modern science and nuclear technology, the use of radioactive materials has increased year by year. While promoting the rapid development of modern science and the national economy, it has also posed new challenges to nuclear safety and radiation safety. Researchers have an increasing demand for accurate, portable and efficient radiation imaging positioning technology. Therefore, various radiation imaging technologies have emerged, such as X / γ-ray transmission imaging, backscatter imaging, CT imaging, neutron photography and resonance photography. The present invention is mainly aimed at the imaging system calibration technology in the field of radiation imaging.

[0003] Calibration is the basis of quantitative radiation measurement, and its purpose is to convert the response value (output value) of the detector into a corresponding measurement value with actual physical meaning. For imaging systems, the response value of each basic pixel unit is usually expressed as amplitude, and the corresponding physical quantity is the ray energy. To measure the energy of each ray or to count the number of rays exceeding a certain energy threshold for imaging, it is necessary to convert the output amplitude of the detector into ray energy, that is, to give an energy calibration curve. With the rapid development of detectors, nuclear electronics and computer technology, an imaging system is generally composed of several to thousands of detector unit channels, and the response rate of each channel needs to be obtained through calibration experiments. Due to the large number of detector channels and the high requirements for channel consistency and accuracy, its calibration poses a challenge.

[0004] The response uniformity within the imaging area is the basis for ensuring the imaging effect. Although the development of multi-channel imaging systems has expanded the imaging area, due to differences in the materials, production processes and electronic systems of scintillators and optoelectronic devices, the responses of different areas may be inconsistent, that is, there is non-uniformity. This non-uniformity of response will seriously affect the imaging quality. Therefore, it is necessary to perform uniformity testing on the imaging system in order to calibrate the detector so that all areas have the same response.

[0005] The current calibration method mainly focuses on energy calibration, which is performed by using monoenergetic gamma rays generated by various radiation sources. The calibration and uniformity test of the entire system are completed by energy calibration of each area of ​​the imaging detector. For detectors with a large number of channels, the workload is extremely large, the efficiency is low, and the speed is slow. The present invention proposes a rapid calibration test method and system for two-dimensional imaging detectors to solve the problems existing in the prior art. Summary of the invention

[0006] The purpose of the present invention is to propose a rapid calibration test method and system for a two-dimensional imaging detector, which can quickly and accurately test the range, linearity and uniformity of all channels of the system, is applicable to various types of imaging detectors, has versatility, and can solve the problems existing in the prior art.

[0007] The present invention is implemented by the following technical scheme: a rapid calibration test method and system for a two-dimensional imaging detector, comprising:

[0008] A radiation source assembly, wherein the radiation source assembly provides gamma rays that are approximately uniformly distributed on the array detector;

[0009] An array detector, wherein the array detector includes a radiation-sensitive scintillator and a photoelectric device array. After receiving the gamma ray, it is absorbed by the scintillator and converted into a large amount of visible light. The visible light is diffused in the scintillator and transmitted to the photoelectric device array, and is converted into an electrical signal and then output to the control module;

[0010] The control module is used to receive the electrical signals generated by the array detector and perform subsequent signal processing, digitization and analysis.

[0011] A further improvement is that the control module includes a data acquisition card and a software program, the data acquisition card processes and digitizes the multi-channel electrical signals and transmits them to the software program, and the software program processes, records and displays the received signals.

[0012] A rapid calibration test method for a rapid calibration test system of a two-dimensional imaging detector comprises the following steps:

[0013] Step 1: Adjust the incident position of the radiation source so that the radiation can cover the entire imaging area to be calibrated;

[0014] Step 2: By adjusting the size, coupling mode, and reflective layer of the scintillator and optoelectronic devices, the diffusion transport mode of visible light in the scintillator is changed, and then the distribution mode of visible light on the optoelectronic device array is adjusted. The detector collects the signal caused by the rays in the entire imaging area and obtains the original data of each electronic channel. Finally, each optoelectronic device has both low-range signals caused by single photons and multi-photons, and high-range signals generated by a large number of photons hitting at the same time, so as to achieve calibration of a wide range, and evaluate the linearity and uniformity of the system through multi-channel data.

[0015] A further improvement is that in step 2, the specific steps of obtaining the photon peak information from the pulse amplitude spectrum of each electronic channel are:

[0016] Step S201: fill in the pulse amplitude spectrum of each channel according to the original data, and obtain the photon peak information from the pulse amplitude spectrum, including the single photon peak, double photon peak, triple photon peak, etc. generated in sequence from a single photon to a large number of photons, use the peak finding function to obtain the center value of each photon peak, obtain the relationship between the number of photons and the photon peak pulse amplitude, and obtain the low-range calibration curve.

[0017] A further improvement is that in step 2, the specific steps of wide range calibration are:

[0018] Step S202: Sum the signals generated by each case on all electronic channels to obtain the energy spectrum of the gamma source used for testing, and obtain the corresponding relationship between the specific ray energy and the pulse amplitude according to the amplitude corresponding to the full energy peak and Compton cutoff characteristic quantity in the energy spectrum and the ray energy of the gamma source used, and obtain the high-range calibration curve;

[0019] Step S203: The low-range calibration curve obtained in step S201 and the high-range calibration curve obtained in step S202 are combined to calculate the wide-range calibration curve of the detector.

[0020] A further improvement is that in step 2, the specific steps of analysis are:

[0021] Step S204: The position of the photoelectric device that generates the maximum output signal in each case is identified as the actual incident position of the ray, and then the characteristic case of the ray incident on the area where each photoelectric device is located is obtained. According to the method of step S202, the energy spectrum when the ray enters each photoelectric device area is obtained. According to step S203, the calibration curve of each photoelectric device is obtained, and the uniformity of the imaging detector is obtained by analyzing the difference in the calibration curves of each photoelectric device.

[0022] The beneficial effects of the present invention are as follows: the present invention provides a rapid calibration test method and system for a two-dimensional imaging detector. In the debugging and calibration link of the two-dimensional imaging detector, a radioactive source is used to generate an approximately uniform radiation field, covering the entire imaging area to be calibrated. After the rays enter the scintillator, a large amount of visible light is generated, which can be dispersed to multiple optoelectronic devices by adjusting the optical transport system; each optoelectronic device has both low-range signals caused by single photons and multi-photons, and high-range signals generated by a large number of photons hitting at the same time; by obtaining the low-range and high-range signals of all optoelectronic devices and electronic channels, a wide-range calibration curve, linearity and uniformity are obtained by data analysis, so as to realize rapid calibration of the entire imaging system. The present invention can effectively improve the calibration efficiency of the imaging system and provide a convenient solution for performance evaluation and calibration of various imaging devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the rapid calibration test system of the present invention.

[0024] Figure 2 It is a schematic diagram of the accumulated single photon energy spectrum under various light fluxes of the present invention.

[0025] Figure 3 It is measured by the imaging detector used in the present invention 137 Cs and 22 Schematic diagram of Na energy spectrum.

[0026] Figure 4 It is a schematic diagram of a calibration curve of a representative area provided by the present invention.

[0027] Figure 5 It is a schematic diagram of the two-dimensional uniformity distribution of the imaging detector used in the present invention.

[0028] Among them: 1. Radiation source assembly; 2. Array detector; 3. Control module. DETAILED DESCRIPTION

[0029] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0030] according to Figure 1 As shown, this embodiment proposes a rapid calibration test system for a two-dimensional imaging detector, including:

[0031] A radiation source assembly 1, wherein the radiation source assembly 1 provides gamma rays that are approximately uniformly distributed on an array detector 2;

[0032] An array detector 2, wherein the array detector 2 includes a radiation-sensitive scintillator and a photoelectric device array. After receiving the gamma ray, it is absorbed by the scintillator and converted into a large amount of visible light. The visible light is diffused in the scintillator and transmitted to the photoelectric device array, and is converted into an electrical signal and then output to the control module;

[0033] The control module 3 is used to receive the electrical signals generated by the array detector 2 and perform subsequent signal processing, digitization and analysis. The control module includes a data acquisition card and a software program. The data acquisition card amplifies, shapes, digitizes, etc. the multi-channel electrical signals and transmits them to the software program. The software program is used to process and count the received signals and record and display the results.

[0034] like Figure 1As shown, the radiation source assembly 1 provides uniformly distributed gamma rays on the array detector 2, and the array detector 2 converts the gamma rays into multi-channel electrical signals, which are then output to the control module 3, and then read out by the back-end electronics (back-end electronics readout usually refers to the process of processing the data signals captured by the front-end sensor or detector in the electronic system design and converting them into useful information) to obtain the raw data of each electronic channel. The raw data enters the software program, which processes and calculates it, obtains the results, and records and displays them.

[0035] according to Figure 2-Figure 5 As shown, this embodiment provides a rapid calibration test method for a rapid calibration test system of a two-dimensional imaging detector, comprising the following steps:

[0036] Step 1: Adjust the incident position of the radiation source so that the radiation quickly covers the entire imaging area to be calibrated;

[0037] Step 2: By adjusting the size, coupling method, reflective layer, etc. of the scintillator and optoelectronic devices, the diffusion transport mode of visible light in the scintillator is changed, and then the distribution mode of visible light on the optoelectronic device array is adjusted, so that each optoelectronic device has both low-range signals caused by single photons and multiple photons, and high-range signals generated by a large number of photons hitting at the same time. The photon peak information is obtained from the pulse amplitude spectrum of each electronic channel, and calibration of a wide range is achieved. The original data of each electronic channel is obtained, and the linearity and uniformity of the system are evaluated through multi-channel data.

[0038] The specific process of the rapid calibration test method is as follows:

[0039] Step S201: The detector collects the signal caused by the rays in the entire imaging area and obtains the raw data of each electronic channel. Based on step 1, the pulse amplitude spectrum of each channel is filled according to the raw data, and the photon peak information is obtained from the pulse amplitude spectrum, including the single photon peak, double photon peak, and three photon peak generated in sequence from a single photon to a large number of photons. The peak search function is used to obtain the center value of each photon peak (corresponding to the pulse amplitude), and the relationship between the number of photons and the pulse amplitude of the photon peak is obtained to obtain the low-range calibration curve.

[0040] Step S202: Sum the signals generated by each case on all electronic channels to obtain the energy spectrum of the gamma source used for testing, and obtain the corresponding relationship between the specific ray energy and the pulse amplitude according to the amplitude corresponding to the full energy peak and Compton cutoff characteristic quantity in the energy spectrum and the ray energy of the gamma source used, and obtain the high-range calibration curve;

[0041] Step S203: The low-range calibration curve obtained in step S201 and the high-range calibration curve obtained in step S202 are combined to calculate the wide-range calibration curve of the detector.

[0042] Step S204: The position of the photoelectric device that generates the maximum output signal in each case is identified as the actual incident position of the ray, and then the characteristic case of the ray incident on the area where each photoelectric device is located is obtained. According to the method of step S202, the energy spectrum when the ray enters each photoelectric device area is obtained. According to step S203, the calibration curve of each photoelectric device is obtained, and the uniformity of the imaging detector is obtained by analyzing the difference in the calibration curves of each photoelectric device.

[0043] In the above steps, the meaning of an instance is: each signal generated represents an instance.

[0044] like Figure 2 As shown in, it is the accumulated single photon energy spectrum under various light fluxes; Figure 3 As shown, the two-dimensional imaging detector detects 137 Cs and 22 Na energy spectrum; Figure 4 As shown, it is the single-photon linearity of the optoelectronic device; Figure 5 The following are the uniformity test results of the two-dimensional imaging detector (the figure shows the uniformity of each channel). 137 Two-dimensional distribution of the Compton cutoff position of the Cs energy spectrum).

[0045] In the field of radiation imaging, scintillators are usually used to detect rays, and the positioning and imaging of rays are achieved through the combination of a large number of optoelectronic devices. It is necessary to calibrate a large number of optoelectronic devices and electronic systems, which is the basis for achieving accurate imaging. In the present invention, in the calibration process of the two-dimensional imaging detector, since the imaging system requires a high resolution, the area of ​​each optoelectronic device is very small, and a radioactive source is used to generate an approximately uniform radiation field. After the rays enter the scintillator, a large amount of visible light is generated, which can be dispersed to multiple optoelectronic devices to achieve the calibration of the system. For each optoelectronic device, when the incident point is far away, the low-range signal caused by single photons and multi-photons is mainly obtained, and the calibration of low flux can be achieved; when the incident point is close, the high-range signal generated by a large number of photons hitting at the same time is mainly obtained, and the calibration of high flux can be achieved. By changing the position of the incident point for scanning, all imaging areas to be calibrated can be covered, and rapid calibration of a large number of channels can be achieved. Afterwards, the linear performance and uniformity of the entire imaging system are evaluated through multi-channel data analysis. Therefore, the present invention can effectively improve the calibration efficiency of the imaging system and provide a convenient solution for performance evaluation and calibration of various imaging devices.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the framework and scope of application of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A rapid calibration test system for a two-dimensional imaging detector, characterized in that: include: A radiation source assembly (1), wherein the radiation source assembly (1) provides gamma rays with a nearly uniform distribution on an array detector (2); An array detector (2), the array detector (2) comprising a radiation-sensitive scintillator and a photoelectric device array, after receiving the gamma ray, it is absorbed by the scintillator and converted into a large amount of visible light, the visible light is diffused in the scintillator and transmitted to the photoelectric device array, converted into an electrical signal and then output to a control module; The control module (3) is used to receive the electrical signal generated by the array detector (2) and perform subsequent signal processing, digitization and analysis.

2. A rapid calibration test method for a two-dimensional imaging detector according to claim 1, characterized in that: The control module includes a data acquisition card and a software program. The data acquisition card processes and digitizes the input electrical signal and transmits it to the software program. The software program is used to process the received digital signal and complete data analysis, recording and display.

3. A rapid calibration test method for a rapid calibration test system for a two-dimensional imaging detector as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Adjust the incident position of the radiation source so that the radiation can cover the entire imaging area to be calibrated; Step 2: By adjusting the size, coupling method, reflective layer, etc. of the scintillator and optoelectronic devices, the diffusion transport mode of visible light in the scintillator is changed, and then the distribution mode of visible light on the optoelectronic device array is adjusted, so that each optoelectronic device has both low-range signals caused by single photons and multiple photons, and high-range signals generated by a large number of photons hitting at the same time, so as to achieve calibration over a wide range. The detector collects the signals caused by the rays in the entire imaging area, obtains the original data of each electronic channel, and evaluates the linearity and uniformity of the system through multi-channel data.

4. The rapid calibration test method for a rapid calibration test system for a two-dimensional imaging detector according to claim 3, characterized in that: In step 2, the specific steps of obtaining the photon peak information from the pulse amplitude spectrum of each electronic channel are: Step S201: fill in the pulse amplitude spectrum of each channel according to the original data, and obtain the photon peak information from the pulse amplitude spectrum, including the single photon peak, double photon peak, triple photon peak, etc. generated in sequence from a single photon to a large number of photons, use the peak finding function to obtain the center value of each photon peak, obtain the relationship between the number of photons and the photon peak pulse amplitude, and obtain the low-range calibration curve.

5. The rapid calibration test method for a rapid calibration test system for a two-dimensional imaging detector according to claim 4, characterized in that: In step 2, the specific steps of wide range calibration are: Step S202: Sum the signals generated by each case on all electronic channels to obtain the energy spectrum of the gamma source used for testing, and obtain the corresponding relationship between the specific ray energy and the pulse amplitude according to the amplitude corresponding to the full energy peak and Compton cutoff characteristic quantity in the energy spectrum and the ray energy of the gamma source used, and obtain the high-range calibration curve; Step S203: The low-range calibration curve obtained in step S201 and the high-range calibration curve obtained in step S202 are combined to calculate the wide-range calibration curve of the detector.

6. The rapid calibration test method for a rapid calibration test system for a two-dimensional imaging detector according to claim 5, characterized in that: In step 2, the specific steps of analysis are: Step S204: The position of the photoelectric device that generates the maximum output signal in each case is identified as the actual incident position of the ray, and then the characteristic case of the ray incident on the area where each photoelectric device is located is obtained. According to the method of step S202, the energy spectrum when the ray enters each photoelectric device area is obtained. According to step S203, the calibration curve of each photoelectric device is obtained, and the uniformity of the imaging detector is obtained by analyzing the difference in the calibration curves of each photoelectric device.

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