分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-03-04
Su, Ning
Liu, Yuanyuan
Wang, Li
Zhang, Jianjie
Zhou, Zhi
Zhao, Xin
Ding, Wenwan
Zheng, Peng
Cheng, Jianping
摘要： Cosmic-ray muons are suitable for non-destructive imaging of large-scale objects. However, due to the low statistics of cosmic-ray muons and the complicated surroundings of transmission muography experiments, trans#2;mission muography often faces challenges such as noise and incomplete data, posing certain difficulties for 3D image reconstruction. This paper applies the SIRT-TV algorithm to muon tomography, conducting a 3D image reconstruction simulation study based on a QinShiHuang tomb phantom. The results indicate that compared to the conventional SIRT algorithm, the SIRT-TV algorithm can effectively suppress artifacts in the reconstructed image, allowing for a more accurate reconstruction of the underground palace. The geometric similarity of the walls reconstructed by SIRT-TV is nearly tripled compared to that of SIRT. This study also discusses the impact of TV-minimization algorithm parameters, and the measurement configurations and durations on the quality of the reconstructed image, providing a reference point for future experiments.
分类： 物理学 >> 电磁学、光学、声学、传热、经典力学和流体动力学 提交时间： 2018-11-11
摘要： Successive images of a scene are captured and then further processed to achieve the moving object tracking. However, due to modulation rate limitations of the spatial light modulator in single-pixel imaging (SPI) system, the imaging frame rate cannot meet the high-resolution and real-time requirements for object tracking. In this paper, we demonstrate a fast object tracking technique based on SPI with an ultra-low sampling rate that is independent of imaging. We construct modulation information that satisfies the projection conditions and can transform 2D images into 1D projection curves. The 1D projection curves, which provide the location information of the moving object, can be obtained with high resolution in real-time, and then the tracking of the moving object is realized. A background subtraction technique for tracking moving objects that removes static components from a scene is also proposed. The proposed technique is verified by computational simulations and laboratory experiments. In the laboratory experiments, we demonstrate that the proposed method can be used to track moving objects with less than 0.2% of the measurements established by the Nyquist criterion, and it presents a resolution of 256×256 pixels at ~177 fps. The reported technique accelerates the tracking speed of SPI and provides an efficient strategy for remote sensing and biomedical applications.
分类： 物理学 >> 核物理学 提交时间： 2025-04-17
摘要： The L-shaped imaging devices are used to reconstruct the intensity distribution of the high-energy X-ray source. The physical model considering the penetration effect of X-ray on the imaging device is established, the transmission imaging matrix is constructed, and the algebraic solution method of source intensity reconstruction is presented. The X-ray source with Gaussian distribution is reconstructed. The reconstruction results show that the artifacts and discontinuities in the center of the reconstructed image using L-Edge device can be improved by L-Rolled Edge device, while L-Cylinder device can further improve the reconstruction quality.
分类： 物理学 >> 核物理学 提交时间： 2025-03-10
Zhang, Mr. JL
Liu, Mr. Xiangman
Sun, Prof. Zhiyu 孙志宇
Fang, Ms. Fang
An, Ms. qi
Lu, Mr. Fenhua
Tang, Dr. Shuwen
Qian, Dr. Yi
Wang, Dr. Shitao
Kong, Dr. Jie
Yang, Dr. Herun
Ma, Mr. Peng
Jiang, Mr. Xuan
SUN, Mr. Yazhou
Yan, Mr. Duo
Zhang, Dr. Xueheng
Zhang, Mr. Yongjie
Yu, Dr. Yuhong
Jiang, Prof. jun
摘要： Cosmic ray muons, characterized by their high energy and penetrative capabilities, provide significant advantages for non-destructive imaging applications, including security inspection, geological exploration, and archaeology. As the muon tomography continues to advance, there is growing demand for precise and efficient muon imaging algorithms. The quality of muon scattering imaging depends on the accuracy of the muon trajectory reconstruction. This paper proposes a neural network-based method utilizing Multi-Wire Drift Chambers (MWDCs), achieving a spatial resolution of 351 \mu m. Additionally, to address challenges of imaging accuracy and track utilization efficiency, an improved method based on the PoCA (Point-of-Closest Approach) algorithm is introduced. This enhancement significantly improves imaging resolution and reconstruction performance, offering a more solution for muon-based imaging solutions.
分类： 物理学 >> 核物理学 提交时间： 2025-02-14
摘要： The L-shaped imaging devices are used to reconstruct the intensity distribution of the high-energy X-ray source. The physical model considering the penetration effect of X-ray on the imaging device is established, the transmission imaging matrix is constructed, and the algebraic solution method of source intensity reconstruction is presented. The X-ray source with Gaussian distribution is reconstructed. The reconstruction results show that the artifacts and discontinuities in the center of the reconstructed image using L-Edge device can be improved by L-Rolled Edge device, while L-Cylinder device can further improve the reconstruction quality.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： In order to improve aerodynamic performance and efficiency, monitoring the geometry and position information of the internal structure with the aero-engine under various operational statuses is an important task. In this paper, a novel design of industrial computed tomography (ICT) system with a linac as x-ray source is proposed to complete the task. The major advantage of the proposed system is that it can provide visualized images of internal structures of the running aero-engine without physical disturbance, which makes it possible to extract the accurate geometry information. The main idea behind this design is to measure the projection data from various views for reconstructions making use of the rotations of the aero-engine blades, instead of the mechanical rotations in the conventional ICT system. However, due to high speed rotation of the aero-engine blades, the system faces more challenges than conventional ICT systems both in data acquisitions and reconstruction algorithms. The challenges and corresponding solutions are presented in this paper. In conclusion, the proposed ICT system provides a powerful tool for monitoring the running aero-engines.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： Properties of two algorithms for iterative reconstruction of SPECT images, LS-MLEM and LS-OSEM,are studied and compared with the ML-EM algorithm in this paper. By using projection data of heavy-noise, their effectiveness in improving SPECT image quality is evaluated. A phantom with hot and cold lesion is used in the investigation. The reconstructed images using LS-MLEM or LS-OSEM show that there is not a rapid increase in image noise,and the best estimate is assuming that the reconstructed images satisfy the statistical model. The major advantage of using LS-MLEM or LS-OSEM algorithm in SPECT imaging is in their ability to accurately control for heavy-noise. And LS-OSEM algorithm obviously improves the convergence rate.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2021-12-31
摘要： The muon radiography imaging technique for high-atomic-number objects (Z) and large-volume objects via muon transmission imaging and muon multiple scattering imaging remains a popular topic in the field of radiation detection imaging. However, few imaging studies have been reported on low and medium Z objects at the centimeter scale. This paper presents an imaging system that consists of three layers of a position-sensitive detector and four plastic scintillation detectors. It acquires data by coincidence detection technique of cosmic-ray muon and its secondary particles. A 3D imaging algorithm based on the density of the coinciding muon trajectory was developed, and 4D imaging that takes the atomic number dimension into account by considering the secondary particle ratio information was achieved. The resultant reconstructed 3D images could distinguish between a series of cubes with 5-mm side lengths and 2-mm intervals. If the imaging time is more than 20 days, this method can distinguish intervals with a width of 1 mm. The 4D images can specify target objects with low, medium, and high Z values.
分类： 物理学 >> 核物理学 提交时间： 2025-05-13
摘要： HADAR is an ultra-wide-angle atmospheric Cherenkov telescope that employs a water-lens optical system, offering significant advantages in detecting gamma-ray sources, including burst, transient, and extended sources. Given its implementation of an innovative transmissive optical technology, the precise pointing accuracy of both the telescope and imaging system is critical, as it directly influences the reconstruction accuracy of gamma-ray events based on Cherenkov light detection. Consequently, rigorous calibration is essential. In this study, we present a calibration method to determine the optical axis orientation of the HADAR imaging system. This method leverages the distinct signal variations observed in the imaging system’s pixel units when bright stars transit through the water-lens field-of-view, thereby enabling the precise calibration of the telescope’s geometric properties. Applying this method to the 0.9-meter HADAR prototype system, we analyzed the imaging characteristics induced by bright stars and performed an accurate calibration of the prototype’s imaging system alignment. Our results confirm the effectiveness of this calibration approach. This technique will be further employed for the alignment and calibration of future large-aperture water-lens telescopes in the HADAR experiment.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-07-04
摘要： Cosmic-ray muons are highly penetrating background-radiation particles found in natural environments. In this study, we develop and test a plastic scintillator muon detector based on machine-learning algorithms. The detector underwent muon position-resolution tests at the Institute of Modern Physics in Lanzhou using a mul tiwire drift chamber (MWDC) experimental platform. In the simulation, the same structural and performance parameters were maintained to ensure the reliability of the simulation results. The Gaussian process regression (GPR) algorithm was used as the position-reconstruction algorithm owing to its optimal performance. The re sults of the Time Difference of Arrival algorithm were incorporated as one of the features of the GPR model to reconstruct the muon hit positions. The accuracy of the position reconstruction was evaluated by comparing the experimental results with Geant4 simulation results. In the simulation, large-area plastic scintillator detectors achieved a position resolution better than 20 mm. In the experimental-platform tests, the position resolutions of the test detectors were 27.9 mm. We also analyzed factors affecting the position resolution, including the crit ical angle of the total internal reflection of the photomultiplier tubes and distribution of muons in the MWDC. Simulations were performed to image both large objects and objects with different atomic numbers. The results showed that the system could image high- and low-Z materials in the constructed model and distinguish objects with significant density differences. This study demonstrates the feasibility of the proposed system, thereby providing a new detector system for muon-imaging applications.
分类： 物理学 >> 核物理学 提交时间： 2023-07-06
摘要： Proton computed tomography (CT) has a distinct practical significance in clinical applications. It eliminates 35% errors caused by the transformation of Hounsfield unit (HU) to relative stopping power (RSP) valueswhen using X-ray CT for positioning andtreatment planning systems (TPSs). Following the development of FLASH proton therapy, there are increased requirements for accurate and rapid positioning in TPSs. Thus, anewrapid proton CT imaging mode is proposed based on sparsely sampled projections. The proton beam wasboosted to 350 MeV by a compact proton linear accelerator (linac). In this study,thecomparisons of the proton scattering with the energyof 350 MeV and 230 MeV are conducted based on GEANT4simulations.Asthe sparsely sampledinformation associated with beam acquisitions at 12angles is not enough for reconstruction, X-ray CT is used as a prior image. The RSP map generated by converting the X-ray CT was constructed based onMonte Carlo simulations. Consideringtheestimationof the most likely path (MLP), the prior image-constrained compressed sensing (PICCS) algorithm isused to reconstruct images from twodifferent phantoms using sparse protonprojections of 350 MeV parallel proton beam. The results show that it is feasible to realize the proton image reconstruction with the rapid protonCT imaging proposed in this paper. It can produce RSP maps withmuchhigher accuracy for TPSs and fast positioning to achieve ultra-fast imaging for real-time image-guided radiotherapy(IGRT) in clinical proton therapyapplications.
分类： 物理学 >> 核物理学 提交时间： 2025-03-27
chen, Dr. kai
Xie, Shipeng
Gao, Dr. Yuan
Gu, Dr. Jiabin
Xi, Dr. Yan
Gao, Mrs. Hongyu
Wang, Mr. Zihao
Wu, Dr. Zhan
Tang, Dr. Hui
Chen, Prof. Yang
摘要： Cone-beam computed tomography (CBCT) is widely used for high-precision three-dimensional imaging in the field of nuclear science and technology (e.g., nuclear medicine radiation therapy, nondestructive testing of nuclear facilities). However, when patients with metal implants in their bodies are examined by CT, the projection data will be contaminated and the CT reconstruction will produce severe metal artifacts affecting the diagnostic accuracy. Therefore, developing high-performance metal artifact reduction (MAR) methods for CBCT is essential for clinical diagnosis. Some of the existing MAR methods ignore physical phenomena such as x-ray scattering during CT imaging. The remaining MAR methods utilize scattering correction as a preprocessing approach, and this non-end-to-end MAR method increases the complexity of the MAR process. In this article, we design an end-to-end MAR method that incorporates both scattering correction and metal segmentation in the projection domain in the same network, followed by morphological post-processing and metal artifact suppression. Both qualitative and quantitative results and analyses in simulated and real data sets illustrate the superiority of this end-to-end MAR method.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： In helical cone-beam computed tomography (CT), Feldkamp-Davis-Kress (FDK) based image reconstruction algorithms are by far the most popular. However, artifacts are commonly met in the presence of lateral projection truncation. The reason is that the ramp filter is global. To restrain the truncation artifacts, an approximate reconstruction formula is proposed based on the Derivative-Hilbert-Backprojection (DHB) framework. In the method, the first order derivative filter is followed by the Hilbert transform. Since the filtered projection values are almost zero by the first order derivative filter, the following Hilbert transform has little influence on the projection values, even though the projections are laterally truncated. The proposed method has two main advantages. First, it has comparable computational efficiency and image quality as well as the conventional helical FDK algorithm for non-truncated projections. The second advantage is that images can be reconstructed with acceptable quality and much lower computational cost in comparison to the Laplace operator based algorithm in cases with truncated projections. To point out the advantages of our method, simulations on the computer and real data experiments on our laboratory industrial cone-beam CT are conducted. The simulated and experimental results demonstrate that the method is feasible for image reconstruction in the case of projection truncation.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： This paper tries to address the problem of binary CT image reconstruction in non-destructive detection with an algorithm based on compressed sensing (CS) and Otsus method, which could reconstruct binary CT image of test object from incomplete detection data. According to binary CT image characteristics, we employ Split-bregman method based on L1/2 regularization to solve piecewise constant region reconstruction. To improve the reconstructed image quality from incomplete detection data, we utilize a priori knowledge and Otsus method as the optimization constraint. In our study, we make numerical simulation to investigate our proposed method, and compare reconstructed results from different reconstruction methods. Finally, the experimental results demonstrate that the proposed method could effectively reduce noise and suppress artifacts, and reconstruct high-quality binary image from incomplete detection data.
分类： 物理学 >> 核物理学 提交时间： 2025-04-17
chen, Dr. kai
Xie, Shipeng
Gao, Mrs. Hongyu
Gao, Dr. Yuan
Xi, Dr. Yan
Li, Mr. Yuchen
Chen, Prof. Yang
摘要： CT images provide medical practitioners with a scientific and intuitive rationale for the diagnosis of clinical diseases. The Internet of Medical Things (IoMT) and telemedicine facilitate the preservation, transmission, and application of medical data, driving the sharing of medical data, especially medical images. Encryption and decryption of CT images distributed in the IoMT and telemedicine are becoming critical because they contain a large amount of private patient-sensitive information and are vulnerable to third-party attacks, resulting in information exposure and privacy leakage . In this paper, we propose an Encryption and Decryption based Gan-attention network (EDG-Net) for CT images in the IoMT and telemedicine. EDG-Net consists of a generator, two discriminators, a domain transfer of attention, and adaptive normalization. In addition, a double encryption and decryption strategy is introduced by EDG-Net to effectively improve the security of the ciphertext image and the fidelity of the decrypted plaintext image. Specifically, during the encryption or decryption phase, the generator transforms the CT images mutually in the plaintext and ciphertext domains. Two discriminators to identify and modify the differences between these two domain transformations, especially to improve the accuracy of the reconstruction during decryption. The parameters of the trained encryption and decryption network are considered as the secret keys of encryption and decryption. Qualitative and quantitative analysis of public and private datasets demonstrates the superior performance of EDG-Net regarding encryption security and robustness, as well as decryption accuracy.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： To achieve a maximum compression of system matrix in positron emission tomography (PET) image reconstruction, we proposed a polygonal image pixel division strategy in accordance with rotationally symmetric PET geometry. Geometrical definition and indexing rule for polygonal pixels were established. Image conversion from polygonal pixel structure to conventional rectangular pixel structure was implemented using a conversion matrix. A set of test images were analytically defined in polygonal pixel structure, converted to conventional rectangular pixel based images, and correctly displayed which verified the correctness of the image definition, conversion description and conversion of polygonal pixel structure. A compressed system matrix for PET image recon was generated by tap model and tested by forward-projecting three different distributions of radioactive sources to the sinogram domain and comparing them with theoretical predictions. On a practical small animal PET scanner, a compress ratio of 12.6:1 of the system matrix size was achieved with the polygonal pixel structure, comparing with the conventional rectangular pixel based tap-mode one. OS-EM iterative image reconstruction algorithms with the polygonal and conventional Cartesian pixel grid were developed. A hot rod phantom was detected and reconstructed based on these two grids with reasonable time cost. Image resolution of reconstructed images was both 1.35 mm. We conclude that it is feasible to reconstruct and display images in a polygonal image pixel structure based on a compressed system matrix in PET image reconstruction.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： CBCT scanners have been widely used in angiography, radiotherapy guidance, mammography and oral maxillofacial imaging. To cut detector size, reduce manufacturing costs and radiation dose while keeping a reasonable FOV, the flat panel detector can be placed off-center horizontally. This scanning configuration extends the FOV effectively. However, each projection is transversely truncated, bringing errors and artifacts in reconstruction. In this paper, a simple but practical method is proposed for this scanning geometry based on truncation compensation and the modified FDK algorithm. Numerical simulations with jaw phantom were conducted to evaluate the accuracy and practicability of the proposed method. A novel CBCT system for maxillofacial imaging is used for clinical test, which is equipped with an off-center small size flat panel detector. Results show that reconstruction accuracy is acceptable for clinical use, and the image quality appears sufficient for specific diagnostic requirements. It provides a novel solution for clinical CBCT system, in order to reduce radiation dose and manufacturing cost.
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