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arXiv 2024年

作者： Zhang, Xin Xie, Jixiong Tan, Yuhang Su, Ting Zhu, Jiongtao Cui, Han Xia, Dongmei Zheng, Hairong Liang, Dong Ge, Yongshuai Research Center for Advanced Detection Materials and Medical Imaging Devices Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Guangdong Shenzhen518055 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Low-grade Energy Utilization Technologies and Systems Ministry of Education of China College of Power Engineering Chongqing University Chongqing400044 China Paul C Lauterbur Research Center for Biomedical Imaging Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Guangdong Shenzhen518055 China Key Laboratory of Biomedical Imaging Science and System Chinese Academy of Sciences Guangdong Shenzhen518055 China National Innovation Center for Advanced Medical Devices Guangdong Shenzhen518131 China

Background: Recently, the popularity of dual-layer flat-panel detector (DL-FPD) based dual-energy cone-beam CT (CBCT) imaging has been increasing. However, the image quality of dual-energy CBCT remains constrained by the Compton scattered X-ray photons. Purpose: The objective of this study is to develop an novel scatter correction method, named as e-Grid, for DL-FPD based CBCT imaging. Methods: In DL-FPD, a certain portion of the X-ray photons (mainly low-energy primary and scattered photons) passing through the object are captured by the top detector layer, while the remaining X-ray photons (mainly high-energy primary and scattered photons) are collected by the bottom detector layer. Based on the two set of distinct low-energy and high-energy measurements, a linear signal model was approximated for the dual-energy primary and scattered signals on DL-FPD. The distributions of X-ray scatters were quickly estimated using this signal model. Monte Carlo (MC) simulation of a water phantom was conducted to verify this newly developed scatter estimation method. Moreover, physical experiments of water phantom, head phantom, and abdominal phantom were carried out to validate the real performance of this proposed scatter correction method. Results: The MC results showed that the e-Grid method was able to generate scatter distributions close to the ground truth. Moreover, the physical experiments demonstrated that the e-Grid method can greatly reduce the shading artifacts in both low-energy and high-energy CBCT images acquired from DL-FPD. On average, the image non-uniformity (NU) was reduced by over 77% in the low-energy CBCT image and by over 66% in the high-energy CBCT image. A a consequence, the accuracy of the decomposed multi-material bases was substantially improved. Conclusion: The Compton scattered X-ray signals could be quickly corrected using the proposed e-Grid method for DL-FPD based dual-energy CBCT imaging systems. Copyright © 2024, The Authors. All rights reser

关键词： Particle beams

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Multidisciplinary and multiscale nanoscience research roadmap based on large scientific facilities

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Science China Chemistry 2024年第8期67卷 2497-2523页

作者： Yuan Zeng Shuhan Zhang Yuecong Guo Yalin Cong Xu Ding Peihua Li Yunxiang Lin Wenzhi Ren Hui Su Weigang Sun Liuxin Xu Guikai Zhang Shihua Chen Yu Chen Weiren Cheng Shengqi Chu Yong Guan Jinru Han Jie Lin Hengjie Liu Zheyi Liu Pan Luo Fanchun Meng Sicong Qiao Zongyin Song Ying Wang Zhao Wu Chenyu Yang Meng Yang Shirui Yang Zi Yin Zhibin Yin Pengjun Zhang Hongyu Zhang Pingping Zheng Jia Zhou Wanlin Zhou Pengfei An He Cheng Chunhai Fan Xingjiu Huang Yong Lei Lina Li Mu Li Qinghua Liu Shuming Peng Li Song Zhihu Sun Yangchao Tian Fangjun Wang Lihua Wang Liming Wang Shiqiang Wei Aiguo Wu Chunlei Xiao Xueming Yang Panchao Yin Jing Zhang Mingxin Zhang Yaling Wang Chunying Chen CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety New Cornerstone Science LaboratoryNational Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Institute of Solid State Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China Ningbo Key Laboratory of Biomedical Imaging Probe Materials and Technology Zhejiang International Cooperation Base of Biomedical Materials Technology and ApplicationCAS Key Laboratory of Magnetic Materials and DevicesNingbo Cixi Institute of Biomedical EngineeringZhejiang Engineering Research Center for Biomedical MaterialsNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China Advanced Energy Science and Technology Guangdong Laboratory Huizhou 516000China College of Chemistry and Chemical Engineering Hunan Normal UniversityChangsha 410081China State Key Laboratory of Luminescent Materials and Devices South China Advanced Institute for Soft Matter Science and TechnologySouth China University of TechnologyGuangzhou 510640China Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China CAS Key Laboratory of Separation Sciences for Analytical Chemistry Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China State Key Laboratory of Molecular Reaction Dynamics Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Institute of Advanced Science Facilities Shenzhen 518107China State Key Laboratory of Coal Conversion Institute of Coal ChemistryChinese Academy of SciencesTaiyuan 030001China State Key Laboratory of Particle Detection and Electronics Institute of High Energy PhysicsChinese Acade

With the advancement of modern science and technology, large scientific facilities are increasingly oriented toward demand and application, and can be used for basic research as well as serving multiple disciplines. Developing large scientific facilities and related analytical technologies enhances understanding of large scientific facilities and popularizes their application in research across multiple disciplines. The combination of light or neutron sources from large scientific facilities and advanced analytical technologies can be achieved for materials structure information, dynamics study of chemical reactions, high dissociation of biomolecules, 3D visualization of energy materials or biological samples, etc. We first introduce the progress of domestic large scientific facilities of synchrotron radiation(SR) and free electron lasers(FELs) with different wavelengths and neutron *** further discuss the comparison between Chinese and typical foreign facilities in X-ray radiation from X-ray tubes, synchrotrons, X-ray FELs, and neutron sources based on physical parameters of light and neutron sources. In addition, we focus on the technological progress and perspectives combined with advanced X-ray radiation and neutron sources of large scientific facilities in China, especially in the nanoscience fields of energy catalysis and biological science. We hope that this roadmap will provide references on technology and methods to experimental users, as well as prospects for future development of technologies based on large research infrastructure facilities. Comprehensive studies and guidelines for basic research to practical application in various disciplines can be made with the assistance of large scientific facilities.

关键词： large scientific facilities synchrotron radiation FEL light sources neutron sources spectroscopic analysis methods X-ray imaging techniques structural information chemical dynamics

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A Second Harmonic Amplitude Conversion Circuit for Power Amplifier

A Second Harmonic Amplitude Conversion Circuit for Power Amp...

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IEEE International Conference on Circuits and Systems (ICCS)

作者： Sikai Chen Boming Su Peiying Cai Tao Peng Xiang Shuxia Yi Wu Guochi Huang Fujian Normal University Fuzhou China Shenzhen Academy of Aerospace Technology Microwave Sensing and Imaging Research Center Shenzhen China Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education Fuzhou China Fujian Provincial Engineering Technology Research Center of Photoelectric Sensing Application Fuzhou China

This paper proposes a second harmonic amplitude conversion circuit for power amplifier, the operating frequency band of this conversion circuit ranges from 5.5 GHz to 6 GHz. In order to reduce the complexity of signal processing encountered by digital pre-distortion technology, the circuit proposed in this paper is based on the injection-locked frequency divider, and proportionally convert the signal amplitude at second harmonic frequency into the signal amplitude at fundamental frequency. Using this technology, the second harmonic distortion signal could be observed through the injection-locked frequency divider output signal. Therefore, it could effectively reduce the complexity of the digital pre-distortion signal processing. The circuit simulation results show that for an input signal with a frequency of 11.6G, a frequency of 5.8G signal which proportional to the amplitude of the input signal is generated at the output.

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A Broadband Voltage Controlled Oscillator with Multi-Band Output

A Broadband Voltage Controlled Oscillator with Multi-Band Ou...

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International Conference on ASIC

作者： Boming Su Sikai Chen Peiyin Cai Tao Peng Xiang Shuxia Yi Wu Guochi Huang Fujian Normal University Fuzhou China Shenzhen Academy of Aerospace Technology Microwave Sensing and Imaging Research Center Shenzhen China Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education Fuzhou China Fujian Provincial Engineering Technology Research Center of Photoelectric Sensing Application Fuzhou China

This paper presents a novel approach to enhance the tuning range performance of a broadband voltage controlled oscillator (VCO) implemented using a 130nm CMOS process. The proposed methodology incorporates second-harmonic extracting technique and third-harmonic synthesis method. The proposed VCO uses a P-only Cross-Couple Pair as a Push-push stage to obtain a second-harmonic signal, and reinforces the signal by active load and common source stages. The proposed third harmonic synthesizer for VCO consists of two square-law mixers, and the third-harmonic is synthesized by the second- harmonic obtained at the common mode node of the two square-law mixers and the fundamental wave of VCO. The simulated tuning ranges of the fundamental signal, second-harmonic signals and third-harmonic signal ranges from 3.07 to 5.08 GHz, 6.20 to 10.16 GHz and 9.03 to 15.24 GHz, Respectively. The simulated phase-noise performances of the fundamental signal of 4.1GHz is -84.7 and -113.5 dBc/Hz at 100kHz and 1 MHz offsets, respectively. The second-harmonic signal of 8.2GHz is -90.49 and -107 dBc/Hz at 100kHz and 1MHz offsets, respectively. The third-harmonic signal of 12.3 GHz is -84.31 and -113.6 dBc/Hz at 100kHz and 1MHz offsets, respectively.

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PNMC: Four-dimensional conebeam CT reconstruction combining prior network and motion compensation

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Computers in Biology and Medicine 2024年 171卷 108145-108145页

作者： Ou, Zhengwei Xie, Jiayi Teng, Ze Wang, Xianghong Jin, Peng Du, Jichen Ding, Mingchao Li, HuiHui Chen, Yang Niu, Tianye School of Computer Science and Engineering Southeast University Nanjing China Shenzhen Bay Laboratory Shenzhen China Beijing Key Laboratory of Magnetic Resonance Imaging Devices and Technology Peking University Third Hospital Beijing China Department of Automation Tsinghua University Beijing China Department of Radiology National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital Chinese Academy of Medical Sciences China Peking Union Medical College China Peking University Aerospace School of Clinical Medicine Aerospace Center Hospital Beijing China Centre de Recherche en Information Biomedical SinoFrancais Rennes France

Four-dimensional conebeam computed tomography (4D CBCT) is an efficient technique to overcome motion artifacts caused by organ motion during breathing. 4D CBCT reconstruction in a single scan usually divides projections into different groups of sparsely sampled data based on the respiratory phases. The reconstructed images within each group present poor image quality due to the limited number of projections. To improve the image quality of 4D CBCT in a single scan, we propose a novel reconstruction scheme that combines prior knowledge with motion compensation. We apply the reconstructed images of the full projections within a single routine as prior knowledge, providing structural information for the network to enhance the restoration structure. The prior network (PN-Net) is proposed to extract features of prior knowledge and fuse them with the sparsely sampled data using an attention mechanism. The prior knowledge guides the reconstruction process to restore the approximate organ structure and alleviates severe streaking artifacts. The deformation vector field (DVF) extracted using deformable image registration among different phases is then applied in the motion-compensated ordered-subset simultaneous algebraic reconstruction algorithm to generate 4D CBCT images. Proposed method has been evaluated using simulated and clinical datasets and has shown promising results by comparative experiment. Compared with previous methods, our approach exhibits significant improvements across various evaluation metrics. © 2024 Elsevier Ltd

关键词： Motion compensation

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Variable frequency deep brain stimulation of subthalamic nucleus to improve freezing of gait in Parkinson's disease

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National Science Review 2024年第6期11卷 102-104页

作者： Fumin Jia Aparna Wagle Shukla Wei Hu Yu Ma Jianguo Zhang Leonardo Almeida Chris Kao Yi Guo Shizhong Zhang Yingqun Tao Zhipei Ling Xin Xu Zhiquan Yang Fan-gang Meng Xinhua Wan Hesheng Liu Peter E.Konard Luming Li National Engineering Laboratory for Neuromodulation Tsinghua University University of Florida Center for Movement Disorders and Neurorestoration Tsinghua University Yuquan Hospital Beijing Tiantan Hospital Capital Medical University School of Medicine Vanderbilt University Peking Union Medical College Hospital ZhuJiang Hospital of Southern Medical University The General Hospital of Shenyang Military Chinese PLA General Hospital Xiangya Hospital Central South University Beijing Neurosurgical Institute Capital Medical University Athinoula A. Martinos Center for Biomedical Imaging Harvard Medical School Precision Medicine & Healthcare Research Center Tsinghua-Berkeley Shenzhen Institute Man-Machine-Environment Engineering Institute School of Aerospace EngineeringTsinghua University Center of Epilepsy Beijing Institute for Brain Disorders

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a welle-stablished therapy for patients with Parkinson’s disease (PD) presenting with medication refractory tremors, motor fluctuations and dyskinesias induced by dopaminergic medications [1]. However,traditional high-frequency stimulation(HFS) does not effectively control axial symptoms such as gait dysfunction,postural instability and freezing of gait(FOG)[2,3].

关键词： parkinson nucleus improve brain deep disease freezing frequency gait stimulation

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Multi-Modal Transformer for Accelerated MR imaging

arXiv

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arXiv 2021年

作者： Feng, Chun-Mei Yan, Yunlu Chen, Geng Xu, Yong Hu, Ying Shao, Ling Fu, Huazhu Shenzhen Key Laboratory of Visual Object Detection and Recognition Harbin Institute of Technology Shenzhen518055 China National Engineering Laboratory for Integrated AeroSpace-Ground-Ocean Big Data Application Technology School of Computer Science and Engineering Northwestern Polytechnical University Xi’an710072 China Terminus Group China Institute of High Performance Computing A*STAR Singapore138632 Singapore

Accelerated multi-modal magnetic resonance (MR) imaging is a new and effective solution for fast MR imaging, providing superior performance in restoring the target modality from its undersampled counterpart with guidance from an auxiliary modality. However, existing works simply combine the auxiliary modality as prior information, lacking in-depth investigations on the potential mechanisms for fusing different modalities. Further, they usually rely on the convolutional neural networks (CNNs), which is limited by the intrinsic locality in capturing the long-distance dependency. To this end, we propose a multi-modal transformer (MTrans), which is capable of transferring multi-scale features from the target modality to the auxiliary modality, for accelerated MR imaging. To capture deep multi-modal information, our MTrans utilizes an improved multi-head attention mechanism, named cross attention module, which absorbs features from the auxiliary modality that contribute to the target modality. Our framework provides three appealing benefits: (i) Our MTrans use an improved transformers for multi-modal MR imaging, affording more global information compared with existing CNN-based methods. (ii) A new cross attention module is proposed to exploit the useful information in each modality at different scales. The small patch in the target modality aims to keep more fine details, the large patch in the auxiliary modality aims to obtain high-level context features from the larger region and supplement the target modality effectively. (iii) We evaluate MTrans with various accelerated multi-modal MR imaging tasks, e.g., MR image reconstruction and super-resolution, where MTrans outperforms state-of-the-art methods on fastMRI and real-world clinical datasets. © 2021, CC BY.

关键词： Magnetic resonance imaging

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An Exploration of Parallel imaging System for Very-low Field (50mT) MRI Scanner

arXiv

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arXiv 2024年

作者： Yang, Lei He, Wei Shen, Sheng He, Yucheng Wu, Jiamin Xu, Zheng National Center for Magnetic Resonance in Wuhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan430071 China The school of Electrical Engineering Chongqing University Chongqing400044 China A.A. Martinos Center for Biomedical Imaging Department of Radiology Massachusetts General Hospital CharlestownMA02129 United States Harvard Medical School BostonMA02115 United States Shenzhen Academy of Aerospace Technology Shenzhen China The school of Life Science Northwestern Polytechnical University Xian China Harbin Institute of Technology Harbin China

Reducing the scanning time of very-low field (VLF) magnetic resonance imaging(MRI) scanners, commonly employed for stroke diagnosis, can enhance patientcomfort and operational efficiency. The conventional parallel imaging (PI)technique for high-field MRI should be tailored to apply here, considering thedifferences in the direction of the main magnetic field and the presence ofnoise. A VLF-specific PI algorithm and phased-array coil are proposed, markingthe first application of PI in VLF MRI. Reconstruction quality is enhanced bydenoising undersampled k-space data using a linear-prediction based Kalmanfilter. Subsequently, the denoised k-space data are nonlinearly mapped from theoriginal space onto a high-dimensional feature space, utilizing a polynomialfeature mapping defined nonlinear frame. Frame parameters are calculated usingauto-calibration signals (ACS) from the center k-space, and missingphase-encoding lines in the original space are estimated using acquired linesin the feature space. An 8-channel phased-array coil, designed for a verticalmain magnetic field, is decoupled using geometric overlap and a low inputimpedance (LII) preamplifier. Healthy volunteer head imaging experiments usingthe proposed PI technique exhibit the lowest mean-squared-error (MSE) value andthe highest peak-signal-to-noise (PSNR) and structural similarity index (SSIM)values compared to two widely used PI methods. The proposed PI techniqueenables the VLF MRI scanner to achieve similar image quality and a 72.5%improvement in signal-to-noise ratio (SNR) compared to fully sampled imageswhile requiring less than 50% of the scan time. We present a PI techniquetailored for VLF MRI scanner for the first time, along with potential researchdirection to achieve greater reduction factor. Copyright © 2024, The Authors. All rights reserved.

关键词： Magnetic resonance imaging

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Surface states ensured by a synthetic Weyl point in one-dimensional plasmonic dielectric crystals with broken inversion symmetry

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Physical Review B 2019年第8期99卷 085441-085441页

作者： Zhenzhen Liu Qiang Zhang Feifei Qin Dasen Zhang Xiangli Liu Jun Jun Xiao Shenzhen Engineering Laboratory of Aerospace Detection and Imaging Harbin Institute of Technology (Shenzhen) Shenzhen 518055 China College of Electronic and Information Engineering Harbin Institute of Technology (Shenzhen) Shenzhen 518055 China Department of Materials Science and Engineering Harbin Institute of Technology (Shenzhen) Shenzhen 518055 China

Weyl points, i.e., peculiar nodal degenerate points in three-dimensional reciprocal space, carry topological charges, therefore giving rise to many intriguing phenomena including topologically protected surface states and chiral anomaly. More importantly, the concept of the Weyl point can be applied in systems with reduced geometrical dimensionality by means of synthetic dimension. Such generalized synthetic Weyl points therefore provide a versatile platform to explore the Weyl-point physics in one or two-dimensional structures. In this work, we study the synthetic Weyl points in one-dimensional plasmonic-dielectric crystals with broken inversion symmetry and further demonstrate that the synthetic Weyl points can ensure the emergence of topological interface states. Instead of using the Zak phase, the emergence of a Weyl point in synthetic space is helpful to understand the underlying physics and the topological properties of the interface states in one-dimensional crystals with broken inversion symmetry. Due to the opposite sign of the surface impedance for plasmonic and dielectric cover medium, the surface states demonstrate distinct properties and locate in separated parameter space regions. Our results show that the synthetic Weyl point provides a potential approach for studying novel electromagnetic modes and facilitates the formation of topologically protected interface states in systems with reduced geometrical dimensions.

关键词： Nanophotonics Topological effects in photonic systems Waveguide arrays Transfer matrix method

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Type-II Dirac point and extreme dispersion in one-dimensional plasmonic-dielectric crystals with off-axis propagation

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Physical Review A 2019年第4期99卷 043828-043828页

Dirac cones exhibit linear crossing dispersion, which results in extraordinary topological properties in the energy bands. When the dispersion around the Dirac points is tilted, type-II or type-III Dirac points are present, which lead to intriguing transport phenomena. With the off-axis wave vector, a two-dimensional (2D) momentum space for one-dimensional (1D) crystals can be constructed. In this work, we revealed that the band structure in the extended 2D momentum space of carefully designed 1D plasmonic-dielectric crystals can be tuned to be highly tilted, forming type-II Dirac cones. In particular, an approximately upright dispersion can be achieved, which is referred to as a class-II Dirac point. Gapless interface states occur across the interface between two connected lattices formed by two distinct inversion-symmetry-broken crystals (i.e., type A and type B). The tilt of the band structure has a crucial influence on the formation of interface states and their sensitivity to the period, which results from the extraordinary properties of the surface impedance in the bulk gap. More importantly, class-II Dirac points exhibit peculiar topological properties. The wavelength area is divided into two regions, each of which can only support interface states for one configuration, type-AB or type-BA connections. Our results show that type-II Dirac points, especially those that are class II, have an underlying impact on the surface impedance and determine the existence of interface states.

关键词： Nanophotonics Topological effects in photonic systems Waveguide arrays Transfer matrix method

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