Subjects: Physics >> Nuclear Physics submitted time 2025-07-03
Abstract： The energy response of an imaging detector based on a monolithic crystal is highly dependent on the position of the gamma ray interaction, which leads to a spectral drift of the imaging detector, known as the spectral drift related to incident position. It deteriorates the energy resolution of the detector and affects the selection of the energy window for imaging, resulting in artefacts in the reconstructed image. Thus, a energy response correction method is proposed to improve the positional consistency of the detector energy response. In both simulation and physical experiments, the method improved the full-energy peak consistency of the monolithic crystal detector, which results in improved energy resolution of the detector, more accurate selection of the energy window, and imaging quality. Especially, in physical experiments, the method converges the peak sites of 365keV energy at each location, which reduced the half-height width of characteristic peak (@365 keV) from 53 to 38 channels, improved the energy resolution by 28.3%, transformed the incomplete mask projection into a complete mask projection, and the signal-to-noise ratio increased from 2.38 to 5.37.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2025-05-15
Abstract： The energy response of an imaging detector based on a monolithic crystal is highly dependent on the position of the gamma ray interaction, which leads to a spectral drift of the imaging detector, known as the spectral drift related to incident position. It deteriorates the energy resolution of the detector and affects the selection of the energy window for imaging, resulting in artefacts in the reconstructed image. Thus, a energy response correction method is proposed to improve the positional consistency of the detector energy response. In both simulation and physical experiments, the method improved the full-energy peak consistency of the monolithic crystal detector, which results in improved energy resolution of the detector, more accurate selection of the energy window, and imaging quality. Especially, in physical experiments, the method converges the peak sites of 365keV energy at each location, which reduced the half-height width of characteristic peak (@365 keV) from 53 to 38 channels, improved the energy resolution by 28.3%, transformed the incomplete mask projection into a complete mask projection, and the signal-to-noise ratio increased from 2.38 to 5.37.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2025-03-25
Abstract： The article presents a high-precision Amplitude-Time to Digital Converter (A-TDC) for using in a Multichannel Analyzer (MCA). Utilizing this method, the MCA quantifies and statistically analyzes the discharge time of nuclear pulse signals, ultimately obtaining the gamma energy spectrum. The autonomous linear discharge circuit presented in this paper significantly simplifies the components and control logic of conventional discharge circuits. By leveraging the underlying logic of the FPGA's internal carry-chain, a delay chain capable of precise time measurement for both leading and trailing edges has been designed, which results in a substantial reduction in logical resource consumption. The high-resolution TDC designed based on the Xilinx Artix-7 series FPGA has a resolution of 69.4ps, and the average value of time measurement precision is 52.3ps. The linear discharge circuit has an inherent nonlinearity of less than 0.05%, and the overall linearity is better than 0.1%. When used in conjunction with a φ25mm×25mm NaI(Tl) detector for measuring the 662 keV full-energy peak of a 137Cs source, the energy resolution achieved is 8.5%.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2025-02-26
Abstract： The article presents a high-precision Amplitude-Time to Digital Converter (A-TDC) for using in a Multichannel Analyzer (MCA). Utilizing this method, the MCA quantifies and statistically analyzes the discharge time of nuclear pulse signals, ultimately obtaining the gamma energy spectrum. The autonomous linear discharge circuit presented in this paper significantly simplifies the components and control logic of conventional discharge circuits. By leveraging the underlying logic of the FPGA's internal carry-chain, a delay chain capable of precise time measurement for both leading and trailing edges has been designed, which results in a substantial reduction in logical resource consumption. The high-resolution TDC designed based on the Xilinx Artix-7 series FPGA has a resolution of 69.4ps, and the average value of time measurement precision is 52.3ps. The linear discharge circuit has an inherent nonlinearity of less than 0.05%, and the overall linearity is better than 0.1%. When used in conjunction with a φ25mm×25mm NaI(Tl) detector for measuring the 662 keV full-energy peak of a 137Cs source, the energy resolution achieved is 8.5%.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2025-01-24
Abstract： The energy response of an imaging detector based on a monolithic crystal is highly dependent on the position of the gamma ray interaction, which leads to a spectral drift of the imaging detector, known as the spectral drift related to incident position. It deteriorates the energy resolution of the detector and affects the selection of the energy window for imaging, resulting in artefacts in the reconstructed image. Thus, a energy response correction method is proposed to improve the positional consistency of the detector energy response. In both simulation and physical experiments, the method improved the full-energy peak consistency of the monolithic crystal detector, which results in improved energy resolution of the detector, more accurate selection of the energy window, and imaging quality. Especially, in physical experiments, the method converges the peak sites of 365keV energy at each location, which reduced the half-height width of characteristic peak (@365 keV) from 53 to 38 channels, improved the energy resolution by 28.3%, transformed the incomplete mask projection into a complete mask projection, and the signal-to-noise ratio increased from 2.38 to 5.37.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2024-12-27
Abstract： The article presents a high-precision Amplitude-Time to Digital Converter (A-TDC) for using in a Multichannel Analyzer (MCA). Utilizing this method, the MCA quantifies and statistically analyzes the discharge time of nuclear pulse signals, ultimately obtaining the gamma energy spectrum. The autonomous linear discharge circuit presented in this paper significantly simplifies the components and control logic of conventional discharge circuits. By leveraging the underlying logic of the FPGA's internal carry-chain, a delay chain capable of precise time measurement for both leading and trailing edges has been designed, which results in a substantial reduction in logical resource consumption. The high-resolution TDC designed based on the Xilinx Artix-7 series FPGA has a resolution of 69.4ps, and the average value of time measurement precision is 52.3ps. The linear discharge circuit has an inherent nonlinearity of less than 0.05%, and the overall linearity is better than 0.1%. When used in conjunction with a φ25mm×25mm NaI(Tl) detector for measuring the 662 keV full-energy peak of a 137Cs source, the energy resolution achieved is 8.5%.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2025-05-09
WANG, Dr. Lei
Li, Dr. Haoxuan
Du, Mr. Yukun
Lu, Dr. Wei
Chen, Mr. Menglei
Zhang, Mr. Peiyu
Zou, Mr. Kefeng
Peng, Mr. Jing
Feng, Mr. Penglei
Abstract： This paper proposes a radiation imaging system based on neural network ray positioning and a monolithic crystal detector. The monolithic crystal detector consists of a 5mm-thick monolithic LaBr3(Ce) crystal coupled with a SiPM array, demonstrating excellent system uniformity under 662 keV gamma-ray irradiation from Cs-137, with an energy resolution of 5.3%. By employing a 32-FCNN ray positioning model, the imaging system achieves an intrinsic spatial resolution of 2.67 mm, with an effective output area covering 81.3% of the detector surface, showing good positional linearity. The imaging capability of the system was evaluated through experiments. Results indicate that when an I-131 source is positioned 82 cm from the detector, with a focal length a of 10 cm (distance between detector and coding plate) and object distance b of 72 cm (distance between radiation source and coding plate), the reconstructed central point-source image using maximum likelihood estimation reconstruction algorithm with 20 iterations achieves a signal-to-noise ratio (SNR) of 14.2. Furthermore, the system exhibits a spatial resolution of 21 mm and an imaging range of ±11.2°.
Peer Review Status:Awaiting Review
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