Method for compensating angle response of radiation detection chip
By constructing an energy correction matrix and solving a system of linear equations, the measurement deviation problem of the thin-layer scintillator radiation detection chip under different incident angles was solved, achieving accurate correction of the directional dose rate and improving the angular response compensation effect of the detector.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA INSTITUTE OF ATOMIC ENERGY
- Filing Date
- 2025-12-12
- Publication Date
- 2026-05-05
AI Technical Summary
The thin-layer scintillator radiation detection chip generates an inconsistent number of pulses at different incident angles, resulting in a large deviation in directional dose rate measurement and making it difficult to achieve angular response compensation.
An array-type SiPM is used to construct an energy correction matrix through simulation calculation and standard radiation field calibration, so as to achieve accurate correction of directional dose rate for different incident angles. The angular response correction matrix is obtained by solving a system of linear equations for compensation.
Without changing the chip size, precise correction for different incident angles was achieved, reducing angular response deviation and enabling the thin-layer scintillator detector to have ideal angular response characteristics similar to those of a spherical detector.
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Figure CN121978744A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of radioactive radiation dose measurement technology, specifically relating to a method for angular response compensation of a radiation detection chip. Background Technology
[0002] Radiation detection chips use thin-layer scintillators (STMs) as gamma-ray probes. Gamma rays react with the scintillator to generate fluorescent photons. A silicon photomultiplier tube (SiPM) collects these photons, which are then amplified to generate pulses. The number of pulses generated is proportional to the directional dose rate. By measuring the number of pulses generated by the SiPM, the directional dose rate of the location can be measured. However, because STMs differ from spherical scintillators in that they have poor angular response, the number of pulses generated by gamma rays incident at different angles varies. Therefore, when radiation detection chips are used to measure the directional dose rate in equipment such as accelerators, the dose rate deviation caused by different incident angles is significant. Therefore, an array of SiPMs is used to correct the energy deposited on each channel of the SiPM by gamma rays incident at different angles, thus achieving angular response compensation for the radiation detection chip. Summary of the Invention
[0003] To address the problems existing in the prior art, the present invention aims to provide a method for angular response compensation of a radiation detection chip, thereby achieving angular response compensation of a thin-layer scintillator radiation detection chip for directional dose rates at different incident angles, and fundamentally solving the measurement deviation problem caused by changes in the incident angle of the radiation source in the radiation detection chip.
[0004] To achieve the above objectives, embodiments of the present invention provide a method for angular response compensation of a radiation detection chip, comprising the following steps:
[0005] Step 1: Test the count rate of deposition in each channel of the array-type SiPM at different incident angles of γ-rays;
[0006] Step 2: Based on the standard dose rate value and the count rate of each channel of the array-type SiPM at different incident angles obtained in Step 1, construct a system of linear equations;
[0007] Step 3: Solve the system of linear equations in Step 2 to obtain the angular response correction matrix;
[0008] Step 4: Correct the chip's angular response based on the angular response correction matrix from Step 3.
[0009] Furthermore, in a specific embodiment, in the method for angular response compensation of a radiation detection chip as described above, in step 1, simulation software is used to simulate and test the count rate of each channel deposited in the array-type SiPM at different incident angles of γ-rays.
[0010] As an optional implementation method, the simulation software is GEANT4 software.
[0011] Furthermore, in a specific embodiment, in the method for angular response compensation of a radiation detection chip as described above, the number of channels in the array-type SiPM is m×m.
[0012] Furthermore, in a specific embodiment, in the method for angular response compensation of a radiation detection chip as described above, in step 1, the incident angle of the γ-rays ranges from 0° to 90°.
[0013] As an optional implementation, the different incident angles are arranged in a gradient according to a set variation interval, and the number of incident angles is m×m.
[0014] Furthermore, in a specific embodiment, in the method for angular response compensation of a radiation detection chip as described above, in step 1, the radiation source is set to 662keV monoenergetic gamma rays from Cs-137 as the incident source.
[0015] Furthermore, in a specific embodiment, in the method for angular response compensation of a radiation detection chip as described above, in step 2, the linear equation system is:
[0016]
[0017] Where H is the standard dose rate value, ε ij N is the calibration coefficient. ij (θ) represents the count rate of the ij channel of the SiPM array at the incident angle θ.
[0018] Furthermore, in a specific embodiment, in the method for angular response compensation of a radiation detection chip as described above, in step 3, the matrix elements of the angular response correction matrix are the calibration coefficients of the corresponding channels of the array-type SiPM.
[0019] Furthermore, in a specific embodiment, in the method for angular response compensation of a radiation detection chip as described above, the angular response correction matrix in step 3 is as follows:
[0020]
[0021] in, Here, i represents the X-axis channel number of the matrix SiPM, and j represents the Y-axis channel number of the SiPM. The corrected count rate for channel ij. The count rate of channel ij obtained from the test.
[0022] The beneficial effects of this invention are as follows: This invention, through simulation calculation and standard radiation field calibration, realizes a method for angular response compensation of radiation detection chips. By establishing an energy correction matrix that maps the "energy distribution pattern" to the "optimal compensation factor," angular response compensation of the chip is achieved without changing the chip size. This enables precise correction of directional dose rates at different incident angles, ensuring that angular response deviations from 0° to 90° are within acceptable limits. Within. Attached Figure Description
[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a schematic diagram of the angular response compensation method for a radiation detection chip in a specific embodiment of the present invention. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0026] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.
[0027] The terms “comprising”, “including”, etc., as used herein indicate the presence of the steps, features, operations, or components, but do not preclude the addition of one or more other steps, features, operations, or components.
[0028] The radiation detection chip uses a thin-layer scintillator as a gamma-ray probe. When gamma rays are incident on the scintillator at an angle θ, energy is deposited within the scintillator through the photoelectric effect, Compton scattering, or pair production. The interaction sites depend on the incident angle and energy. With perpendicular incidence, the interaction is concentrated in a small region near the incident surface; with oblique incidence, the interaction points move along the incident direction within the scintillator. The deposited energy excites scintillator atoms, generating fluorescent photons upon de-excitation. The photon yield is proportional to the deposited energy, reaching tens of thousands of photons per MeV. Fluorescent photons are emitted isotropically within the scintillator, undergoing multiple reflections, scattering, and absorptions before some reach the SiPM array surface. The SiPM array absorbs these photons, generating photoelectrons, which are amplified by avalanche amplification to form a measurable electrical signal. The output of each pixel is proportional to the number of photons it collects.
[0029] Because thin-layer scintillators differ from spherical scintillators, thin-layer scintillators have poor angular response, resulting in inconsistent pulse counts from gamma rays incident at different angles. This makes it difficult for radiation detection chips to simultaneously achieve detection efficiency and directional accuracy. This invention employs an m×m channel array-type SiPM, transforming the energy deposition distribution, initially considered interference, generated under different angular radiation into a crucial information source for angle identification. Through simulation calculations and standard radiation field calibration, an energy correction matrix is established that maps the "energy distribution pattern" to the "optimal compensation factor." In real-time measurements, the chip analyzes the acquired energy distribution pattern, queries this database, and automatically applies compensation, achieving precise correction of the directional dose rate at different incident angles. Ultimately, this enables the flattened detection chip to possess near-ideal angular response characteristics similar to a spherical detector.
[0030] In some embodiments, the present invention provides a method for angular response compensation of a radiation detection chip, comprising the following steps:
[0031] Step 1: Test the count rate of deposition in each channel of the array-type SiPM at different incident angles of γ-rays; the incident angle of γ-rays ranges from 0° to 90°, and different incident angles can be arranged in a gradient according to the set variation intervals, and the number of incident angles is the same as the number of channels of the array-type SiPM.
[0032] Step 2: Based on the standard dose rate value and the count rate of each channel of the array-type SiPM at different incident angles obtained in Step 1, construct a system of linear equations; that is, the sum of the products of the count rate of each channel of the array-type SiPM at the same incident angle and the calibration coefficient of the corresponding channel is equal to the standard dose rate value.
[0033] Step 3: Solve the system of linear equations in Step 2 to obtain the angle response correction matrix; the matrix elements of the angle response correction matrix are the calibration coefficients of the corresponding channels of the array-type SiPM.
[0034] Step 4: Correct the chip's angular response based on the angular response correction matrix from Step 3.
[0035] The incident angle of gamma rays is θ (incident range from 0° to 90°). The gamma rays react with the scintillator to produce fluorescent photons. Since the light collection efficiency of the array-type SiPM varies with position, the position signal (X, Y) of each channel of the SiPM array reflects the specific point where the event occurred. When the ray is incident at 0°, the SiPM deposits the highest energy only at the incident point, and the energy deposited around the incident point is relatively low. When the ray deflects from 0° to 90°, the number of channels triggered by the SiPM array and the deposited energy change with position.
[0036] The count rate N of each channel deposited in the SiPM array was tested at different incident angles. ij (ij = the i-th channel of the SiPM array on the X-axis and the j-th channel on the Y-axis), and based on the relationship between the standard field dose equivalent rate and the count rate of all corrected channels, the angle response correction matrix can be obtained, and the angle response of the chip can be corrected.
[0037]
[0038]
[0039] , where i is the X-axis channel number of the SiPM array and j is the Y-axis channel number of the SiPM array. The corrected count rate for channel ij. The count rate of channel ij obtained from the test. is the conversion factor from count rate to dose rate. H is the standard field dose equivalent rate value. m is the m×m channel SiPM array.
[0040] Solving the linear equations based on the above relationships yields the angle response correction coefficients ε. An angle response correction matrix is then constructed from these coefficients, allowing for the correction of the angle response of the chip's measured values.
[0041] Example
[0042] This embodiment provides a method for angular response compensation of a radiation detection chip, which is simulated using GEANT4 software.
[0043] Detector Construction: The simulated array-type SiPM has 4×4 channels, with a single channel photosensitive area of 3mm×3mm. A CsI(Tl) crystal with the same area as the array-type SiPM is placed on the surface of the array-type SiPM as a scintillator. The detector structure is as follows. Figure 1 As shown. The incident angle of the γ-ray is θ (the incident range is from 0° to 90°). The γ-ray reacts with the scintillator to produce fluorescent photons. Since the light collection efficiency of the array-type SiPM varies with position, the position signal (X, Y) of each channel of the SiPM array reflects the specific point where the event occurred.
[0044] Source settings: The radiation source is set to 662 keV monoenergetic gamma rays from Cs-137 as the incident source, and the number of particles per simulation is 10. 5 One, that is Corresponding to the specific method of this invention, the number of particles in all channels of the corrected array-type SiPM is 10. 5 indivual.
[0045] Data acquisition: The incident angles θ of the gamma rays are θ=0°, 15°, 30°, 45°, 60°, and 90°. The gamma rays are irradiated into the detector at each incident angle θ, and the energy deposited in each channel of the detector for each event is acquired. When the energy exceeds the threshold, it is recorded as a valid event.
[0046] The number of valid events was recorded at θ = 0°, 15°, 30°, 45°, 60°, and 90°, respectively. The count rate of each channel at each angle was recorded. Based on the aforementioned relationship, a system of linear equations was solved to obtain the angle response calibration coefficient ε. An angle response correction matrix was constructed from the angle response coefficient, and the angle response of the chip measurement values was corrected using the angle response correction matrix.
[0047] The baseline count is based on an incident angle of 0°, i.e., perpendicular to the SiPM array (equal to the standard dose rate value).
[0048] A system of linear equations was constructed using the standard dose rate value and the count rate of each channel of the SiPM array at different incident angles θ.
[0049]
[0050] Where H is the standard dose rate value, ε ij N is the calibration coefficient. ij (θ) represents the count rate of the ij channel of the SiPM array at the incident angle θ.
[0051] For a 4×4 SiPM array, m=4, each angle θ corresponds to an equation, with 16 unknown coefficients ε. ij Because there are 16 unknown calibration coefficients, solving the linear equation system requires 16 independent equations, i.e., 16 (equal to the total number of channels in the SiPM array) count rates for each channel of the 4×4 SiPM array at different incident angles. Therefore, interpolation is performed between the incident angles of 0° and 90°, uniformly increasing the simulated angle. The simulated incident angles are 0°, 6°, 12°, 18°, 24°, 30°, 36°, 42°, 48°, 54°, 60°, 66°, 72°, 78°, 84°, and 90°. ε is obtained by solving the linear equation system. 11 ε 12 …ε 44 There are 16 solutions in total.
[0052] In actual testing, N was obtained at the incident angle θ. 11 N 12 …N 44 The count rate of a total of 16 channels, then the dose rate value
[0053]
[0054] For SiPM arrays with different channel numbers, the number of calculated angles can be reduced accordingly, but since 0°, 15°, 30°, 45°, 60°, and 90° are commonly used incident angles, they must be retained.
[0055] Those skilled in the art will understand that the specific order of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order of steps in the process can be rearranged without departing from the scope of the invention. The appended methods provide elements of various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.
[0056] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. Thus, the invention also intends to include such variations and adaptations if they fall within the scope of the claims and their equivalents.
[0057] The above embodiments are merely illustrative examples of the present invention. The present invention may also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of protection of the present invention should be defined by the claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.
Claims
1. A method for angular response compensation of a radiation detection chip, characterized in that, Includes the following steps: Step 1: Test the count rate of deposition in each channel of the array-type SiPM at different incident angles of γ-rays; Step 2: Based on the standard dose rate value and the count rate of each channel of the array-type SiPM at different incident angles obtained in Step 1, construct a system of linear equations; Step 3: Solve the system of linear equations in Step 2 to obtain the angular response correction matrix; Step 4: Correct the chip's angular response based on the angular response correction matrix from Step 3.
2. The method for angular response compensation of a radiation detection chip as described in claim 1, characterized in that: In step 1, simulation software is used to simulate and test the count rate of deposition in each channel of the array-type SiPM at different incident angles of γ-rays.
3. The method for angular response compensation of a radiation detection chip as described in claim 2, characterized in that: The simulation software is GEANT4.
4. The method for angular response compensation of a radiation detection chip as described in claim 1, characterized in that: The array-type SiPM has m×m channels.
5. The method for angular response compensation of a radiation detection chip as described in claim 1, characterized in that: In step 1, the incident angle of the γ-rays ranges from 0° to 90°.
6. The method for angular response compensation of a radiation detection chip as described in claim 4, characterized in that: In step 1, the different incident angles are arranged in a gradient according to a set variation interval, and the number of incident angles is m×m.
7. The method for angular response compensation of a radiation detection chip as described in claim 1, characterized in that: In step 1, the radiation source is set to 662keV monoenergetic gamma rays from Cs-137 as the incident source.
8. The method for angular response compensation of a radiation detection chip as described in claim 4, characterized in that: In step 2, the system of linear equations is as follows: Where H is the standard dose rate value, ε ij N is the calibration coefficient. ij (θ) represents the count rate of the ij channel of the SiPM array at the incident angle θ.
9. The method for angular response compensation of a radiation detection chip as described in claim 1, characterized in that: In step 3, the matrix elements of the angular response correction matrix are the calibration coefficients of the corresponding channels of the array-type SiPM.
10. The method for angular response compensation of a radiation detection chip as described in claim 9, characterized in that: In step 3, the angular response correction matrix is as follows: in, Here, i represents the X-axis channel number of the matrix SiPM, and j represents the Y-axis channel number of the SiPM. The corrected count rate for channel ij. The count rate of channel ij obtained from the test.