In theory, we find that the actual function of the analyzer grating in the Talbot–Lau interferometer is segmenting the self-images of the phase grating and choosing integral areas, which make sure that each period of...In theory, we find that the actual function of the analyzer grating in the Talbot–Lau interferometer is segmenting the self-images of the phase grating and choosing integral areas, which make sure that each period of self-images in one detector pixel contributes the same signal to the detector. Furthermore, in the case of the lack of an analyzer grating, the shifting curves are still existent in theory as long as the number of fringes is non-integral in a detector pixel, which is a sufficient condition for creating shifting curve. The sufficient condition is available for not only the Talbot–Lau interferometer and the inverse geometry of Talbot–Lau interferometer, but also the x-ray phase contrast imaging system based on geometrical optics. In practical applications, we propose a method to improve the performances of the existing systems by employing the sufficient condition. This method can shorten the system length, is applicable to large period gratings, and can use the detectors with large pixels and large field of view. In addition, the experimental arrangement can be simplified due to the lack of an analyzer grating. In order to improve detection sensitivity and resolution, we also give an optimal fringe period.We believe that the theory and method proposed here is a step forward for x-ray phase contrast imaging.展开更多
Grating-based X-ray phase contrast imaging has been demonstrated to he an extremely powerful phase-sensitive imaging technique. By using two-dimensional (2D) gratings, the observable contrast is extended to two refr...Grating-based X-ray phase contrast imaging has been demonstrated to he an extremely powerful phase-sensitive imaging technique. By using two-dimensional (2D) gratings, the observable contrast is extended to two refraction directions. Recently, we have developed a novel reverse-projection (RP) method, which is capable of retrieving the object information efficiently with one-dimensional (1D) grating-based phase contrast imaging. In this contribution, we present its extension to the 2D grating-based X-ray phase contrast imaging, named the two-dimensional reverse- projection (2D-RP) method, for information retrieval. The method takes into account the nonlinear contributions of two refraction directions and allows the retrieval of the absorption, the horizontal and the vertical refraction images. The obtained information can be used for the reconstruction of the three-dimensionak phase gradient field, and for an improved phase map retrieval and reconstruction. Numerical experiments are carried out, and the results confirm the validity of the 2D-RP method.展开更多
With the spatial coherence of X-rays and high flux and brightness of the 3rd generation synchrotron radiation facility,X-ray phase contrast microscopy(XPCM)at Shanghai Synchrotron Radiation Facility(SSRF)can provide h...With the spatial coherence of X-rays and high flux and brightness of the 3rd generation synchrotron radiation facility,X-ray phase contrast microscopy(XPCM)at Shanghai Synchrotron Radiation Facility(SSRF)can provide high resolution dynamic imaging of low electron density materials in principle.In this paper,we investigated the cavitation and water-refilling processes in rice and bamboo leaves utilizing XPCM at SSRF.The occurrence of xylem cavitation was recorded in vivo.The study also revealed that under different dehydration conditions,cavitation occurs in different degrees,and therefore,the refilling process is different.The results demonstrate that SSRF can provide high enough fluxes to study dynamic processes in plants in real-time,and XPCM is expected to be a promising method to reveal the mechanisms of cavitation and its repair in plants nondestructively.展开更多
X-ray in-line phase contrast imaging enables weakly to absorb specimens to be imaged successfully with high resolution and definition. In this paper we use computer simulation method to analyze how each parameter infl...X-ray in-line phase contrast imaging enables weakly to absorb specimens to be imaged successfully with high resolution and definition. In this paper we use computer simulation method to analyze how each parameter influences the quality of the image. It can avoid wasting unnecessary time and materials in the course of experiment to get ideal images.展开更多
Dual-phase and three-phase grating x-ray interference is a promising new technique for grating-based x-ray differential phase contrast imaging.Dual-phase grating interferometers have been relatively completely studied...Dual-phase and three-phase grating x-ray interference is a promising new technique for grating-based x-ray differential phase contrast imaging.Dual-phase grating interferometers have been relatively completely studied and discussed.In this paper,the corresponding imaging fringe formula of the three-phase grating interferometer is provided.At the same time,the similarities and differences between the three-phase grating interferometer and the dual-phase grating interferometer are investigated and verified,and that the three-phase grating interferometer can produce large-period moiréfringes without using the analyzing grating is demonstrated experimentally.Finally,a simple method of designing three-phase grating and multi-grating imaging systems from geometric optics based on the thin-lens theory of gratings is presented.These theoretical formulas and experimental results provide optimization tools for designing three-phase grating interferometer systems.展开更多
The optical design of near-infrared phase contrast imaging(NI-PCI)diagnosis on HL-2A is introduced in this paper.This scheme benefits from the great progress of near-infrared laser technology and is a broadening of tr...The optical design of near-infrared phase contrast imaging(NI-PCI)diagnosis on HL-2A is introduced in this paper.This scheme benefits from the great progress of near-infrared laser technology and is a broadening of traditional phase contrast technology.This diagnostic can work as a keen tool to measure plasma wavenumber spectra by inferring string-integrated plasma density fluctuations.Design of both the front optical path which is the path before the laser transmitting into the tokamak plasma and the rear optics which is the path after the laser passing through the plasma is detailed.The 1550 nm laser is chosen as the probe beam and highprecision optical components are designed to fit the laser beam,in which a phase plate with a 194-nm-deep silver groove is the key.Compared with the conventional 10.6μm laser-based PCI system on HL-2A,NI-PCI significantly overcomes the unwanted phase scintillation effect and promotes the measurement capability of high-wavenumber turbulence with an increased maximal measurable wavenumber from 15 cm^(-1)to 32.6 cm^(-1).展开更多
TRISO (tristructural-isotropic) fuel is a type of micro fuel particles used in high-temperature gas-cooled reactors (HTGRs). Among the quality evaluation methods for such particles, inqine phase contrast imaging t...TRISO (tristructural-isotropic) fuel is a type of micro fuel particles used in high-temperature gas-cooled reactors (HTGRs). Among the quality evaluation methods for such particles, inqine phase contrast imaging technique (PCI) is more feasible for nondestructive measurement. Due to imaging hardware limitations, high noise level is a distinct feature of PCI images, and as a result, the dimensional measurement accuracy of TRISO-coated fuel particles decreases. Therefore, we propose an improved denoising hybrid model named as NL P-M model which introduces non-local theory and retains the merits of the Perona-Malik (P-M) model. The improved model is applied to numerical simulation and practical PCI images. Quanti- tative analysis proves that this new anisotropic diffusion model can preserve edge or texture information effectively, while ruling out noise and distinctly decreasing staircasing artifacts. Especially during the process of coating layer thickness measurement, the NL P-M model makes it easy to obtain continuous contours without noisy points or fake contour segments, thus enhancing the measurement accuracy. To address calculation complexity, a graphic processing unit (GPU) is adopted to realize the acceleration of the NL P-M denoising.展开更多
X-ray grating interferometer has attracted widely attention in the past years due to its capability in achieving x-ray phase contrast imaging with low brilliance source. However, the widely used phase stepping informa...X-ray grating interferometer has attracted widely attention in the past years due to its capability in achieving x-ray phase contrast imaging with low brilliance source. However, the widely used phase stepping information extraction method reduces system stability and prolongs data acquisition time by several times compared with conventional x-ray absorption- based imaging. The mechanical stepping can be avoided by using a staggered grating, but at the cost of low vertical spatial resolution. In this paper, employing a modified staggered grating and the angular signal radiography, we proposed a single-shot grating-based x-ray differential phase contrast imaging with decent vertical spatial resolution. The theoretical framework was deduced and proved by numerical experiments. Absorption, phase, and scattering computed tomography can be performed without phase stepping. Therefore, we believe this fast and highly stable imaging method with decent resolution would be widely applied in x-ray grating-based phase contrast imaging.展开更多
Tin(Sn)holds great promise as an anode material for next-generation lithium(Li)ion batteries but suffers from massive volume change and poor cycling performance.To clarify the dynamic chemical and microstructural evol...Tin(Sn)holds great promise as an anode material for next-generation lithium(Li)ion batteries but suffers from massive volume change and poor cycling performance.To clarify the dynamic chemical and microstructural evolution of Sn anode during lithiation and delithiation,synchrotron X-ray energydispersive diffraction and X-ray tomography are simultaneously employed during Li/Sn cell operation.The intermediate Li-Sn alloy phases during de/lithiation are identified,and their dynamic phase transformation is unraveled which is further correlated with the volume variation of the Sn at particle-and electrode-level.Moreover,we find that the Sn particle expansion/shrinkage induced particle displacement is anisotropic:the displacement perpendicular to the electrode surface(z-axis)is more pronounced compared to the directions(x-and y-axis)along the electrode surface.This anisotropic particle displacement leads to an anisotropic volume variation at the electrode level and eventually generates a net electrode expansion towards the separator after cycling,which could be one of the root causes of mechanical detachment and delamination of electrodes during long-term operation.The unraveled chemical evolution of Li-Sn and deep insights into the microstructural evolution of Sn anode provided here could guide future design and engineering of Sn and other alloy anodes for high energy density Li-and Na-ion batteries.展开更多
An x-ray scintillator screen with a special structure, functioning as detector and analyser grating, was proposed for collecting the interferogram of differential phase contrast imaging without absorption grating and ...An x-ray scintillator screen with a special structure, functioning as detector and analyser grating, was proposed for collecting the interferogram of differential phase contrast imaging without absorption grating and difficulty of fabrication by a state of the art technique. On the basis of phase grating diffraction, a detecting model of the scintillator screen was built for analysing the phase and absorption information of objects. According to the analysis, a new method of phase retrievals based on two-images and the optimal structure of screen were presented.展开更多
BACKGROUND Many imaging methods such as ultrasonography,computed tomography(CT),magnetic resonance imaging,and endoscopy are used to identify the problems or complications that occur in the perioperative period and to...BACKGROUND Many imaging methods such as ultrasonography,computed tomography(CT),magnetic resonance imaging,and endoscopy are used to identify the problems or complications that occur in the perioperative period and to determine the appropriate therapeutic approach.Specialists at surgical clinics and intensive care units sometimes need diagnostic procedures that can give quick results or reveal unexpected results.In particular,rapid on-site evaluation of patients followed under intensive care conditions has several advantages.AIM To determine the problems developing in patients in the perioperative period by contrast-enhanced abdominal X-ray(CE-AXR),revealing their current status or defining the effectiveness of CE-AXR.METHODS The files of the patients who underwent hepatopancreatobiliary or upper gastrointestinal surgery,whose CE-AXR film was taken,were reviewed retrospectively.Abdominal X-ray radiographs taken after ingestion of a watersoluble contrast agent(iohexol,300 mg,50 cc vial)and its application in a drain,nasogastric tube,or stent were evaluated.The contribution of the data obtained in patients who underwent CE-AXR to the diagnosis,follow-up,and treatment processes and the effectiveness of the application were investigated.RESULTS CE-AXR was applied to 131 patients in our clinic,most of whom underwent hepatopancreatobiliary or upper gastrointestinal surgery.It was determined that the data obtained from CE-AXR films taken in 98(74.8%)of the patients contributed to the diagnosis,treatment,and follow-up expectations and positively affected the clinical processes.CONCLUSION CE-AXR is a simple procedure that can be applied anywhere,especially in intensive care patients and at bedside,with a portable X-ray device.The simplicity of the procedure,less radiation exposure for the patients,less time wastage,reduction in the CT and endoscopy procedure burden and costs,quick results,rapid assessment of the situation,and enabling the monitoring of processes with repetitive procedures are important advantages.X-rays taken will be useful in terms of being a reference value during the follow-up period of the patient and determining the situation in medicolegal processes.展开更多
Imaging blood vessels is of importance for determining the vascular distribution of organs and tumors.Phase-contrast X-ray imaging can reveal the vessels in much more detail than conventional X-ray absorption method.V...Imaging blood vessels is of importance for determining the vascular distribution of organs and tumors.Phase-contrast X-ray imaging can reveal the vessels in much more detail than conventional X-ray absorption method.Visualizing murine liver microvasculature ex vivo with phase-contrast X-ray imaging was performed at Shanghai Synchrotron Radiation Facility.Barium sulfate and physiological saline were used as contrast agents for the blood vessels.Blood vessels of <Φ20μm could be detected by replacing resident blood with physiological saline or barium sulfate.An entire branch of the portal vein (from the main axial portal vein to the ninth generation of branching) could be captured in a single phase-contrast image.It is demonstrated that selective angiography based on phase contrast X-ray imaging,with a physiological material of low Z elements (such as saline) being the contrast agent,is a viable imaging strategy.Further efforts will be focused on using the technique to image tumor angiogenesis.展开更多
An experimental study on nondestructive X-ray imaging of inner structure of soft tissues in phase con-trast has been conducted with Beijing Synchrotron Radiation Facility (BSRF). Modification to the beamline setupwas ...An experimental study on nondestructive X-ray imaging of inner structure of soft tissues in phase con-trast has been conducted with Beijing Synchrotron Radiation Facility (BSRF). Modification to the beamline setupwas made to enlarge the X-ray beam section and consequently larger samples could be imaged. In-line setup was em-ployed for experiments. Results on a series of samples were given and soft-tissue details of less than 50 μm inside afresh goldfish were obtained. Diagnosis of tumor in its early stage was also investigated taking SD rats as the model.Tumor at the size of ~ 100μm was observed. Potential of this technique in clinic diagnosis was discussed.展开更多
A time-resolved x-ray diffraction technique is employed to monitor the structural transformation of laser-shocked bismuth.Results reveal a retarded transformation from the shock-induced Bi-Ⅴphase to a metastable Bi-...A time-resolved x-ray diffraction technique is employed to monitor the structural transformation of laser-shocked bismuth.Results reveal a retarded transformation from the shock-induced Bi-Ⅴphase to a metastable Bi-Ⅳphase during the shock release,instead of the thermodynamically stable Bi-Ⅲphase.The emergence of the metastable Bi-Ⅳphase is understood by the competitive interplay between two transformation pathways towards the Bi-Ⅳand Bi-Ⅲ,respectively.The former is more rapid than the latter because the Bi-Ⅴto B-Ⅳtransformation is driven by interaction between the closest atoms while the Bi-Ⅴto B-Ⅲtransformation requires interaction between the second-closest atoms.The nucleation time for the Bi-Ⅴto Bi-Ⅳtransformation is determined to be 5.1±0.9 ns according to a classical nucleation model.This observation demonstrates the importance of the formation of the transient metastable phases,which can change the phase transformation pathway in a dynamic process.展开更多
The amorphous phase-change materials with spontaneous structural relaxation leads to the resistance drift with the time for phase-change neuron synaptic devices. Here, we modify the phase change properties of the conv...The amorphous phase-change materials with spontaneous structural relaxation leads to the resistance drift with the time for phase-change neuron synaptic devices. Here, we modify the phase change properties of the conventional Ge_2Sb_2Te_5(GST) material by introducing an SnS phase. It is found that the resistance drift coefficient of SnS-doped GST was decreased from 0.06 to 0.01. It can be proposed that the origin originates from the precipitation of GST nanocrystals accompanied by the precipitation of SnS crystals compared to single-phase GST compound systems. We also found that the decrease in resistance drift can be attributed to the narrowed bandgap from 0.65 to 0.43 eV after SnS-doping. Thus, this study reveals the quantitative relationship between the resistance drift and the band gap and proposes a new idea for alleviating the resistance drift by composition optimization, which is of great significance for finding a promising phase change material.展开更多
A fast and simple method to extract phase-contrast images from interferograms is proposed, and its effectiveness is demonstrated through simulation and experiment. For x-ray differential phase contrast imaging, a stro...A fast and simple method to extract phase-contrast images from interferograms is proposed, and its effectiveness is demonstrated through simulation and experiment. For x-ray differential phase contrast imaging, a strong attenuation signal acts as an overwhelming background intensity that obscures the weak phase signal so that no obvious phase-gradient information is detectable in the raw image. By subtracting one interferogram from another, chosen at particular intervals,the phase signal can be isolated and magnified.展开更多
In-line x-ray phase contrast imaging has attracted much attention due to two major advantages: its effectiveness in imaging weakly absorbing materials, and the simplicity of its facilities. In this paper a comprehens...In-line x-ray phase contrast imaging has attracted much attention due to two major advantages: its effectiveness in imaging weakly absorbing materials, and the simplicity of its facilities. In this paper a comprehensive theory based on Wigner distribution developed by Wu and Liu [Med. Phys. 31 2378-2384 (2004)] is reviewed. The influence of x-ray source and detector on the image is discussed. Experiments using a microfocus x-ray source and a CCD detector are conducted, which show the role of two key factors on imaging: the tube voltage and tube current. High tube current and moderate tube voltage are suggested for imaging.展开更多
For weakly absorbing materials, image contrast can be enhanced by phase contrast in formation. The effectiveness of the in-line phase contrast technique relies on its ability to record intensity data which contain inf...For weakly absorbing materials, image contrast can be enhanced by phase contrast in formation. The effectiveness of the in-line phase contrast technique relies on its ability to record intensity data which contain information on the x- ray's phase shift. Four kinds of approaches to the relationship between intensity distribution and phase shift axe reviewed and discussed. A micro-focal x-ray source with high geometrical magnification is used to acquire phase contrast images. A great improvement on image quality is shown and geometrical parameters axe modified for comparison between different imaging positions.展开更多
A new algorithm for phase contrast X-ray tomography under holographic measurement was proposed in this paper. The main idea of the algorithm was to solve the nonlinear phase retrieval problem using the Newton iterativ...A new algorithm for phase contrast X-ray tomography under holographic measurement was proposed in this paper. The main idea of the algorithm was to solve the nonlinear phase retrieval problem using the Newton iterative method. The linear equations for the Newton directions were proved to be ill-posed and the regularized solutions were obtained by the conjugate gradient method. Some numerical experiments with computer simulated data were presented. The efficiency, feasibility and the numerical stability of the algorithm were illustrated by the numerical experiments. Compared with the results produced by the linearized phase retrieval algorithm, we can see that the new algorithm is not limited to be only efficient for the data measured in the near-field of the Fresnel region and thus it has a broader validity range.展开更多
The principle of dual-energy x-ray grating phase-contrast imaging(DEPCI) is clarified by using the theory of x-ray interference and Fresnel diffraction. A new method of retrieving phase from the two interferograms is ...The principle of dual-energy x-ray grating phase-contrast imaging(DEPCI) is clarified by using the theory of x-ray interference and Fresnel diffraction. A new method of retrieving phase from the two interferograms is proposed for DEPCI,and its feasibility is verified via simulation. Finally, the proposed method applied to DEPCI experiment demonstrates the effectiveness of the method. This paper lays the theoretical foundation for performance optimization of DEPCI and the further integration of DEPCI and computed tomography.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11074172 and 11674232)the National Key Basic Research Program,China(Grant No.2012CB825804)the National Special Foundation for Major Science Instrument,China(Grant No.61227802)
文摘In theory, we find that the actual function of the analyzer grating in the Talbot–Lau interferometer is segmenting the self-images of the phase grating and choosing integral areas, which make sure that each period of self-images in one detector pixel contributes the same signal to the detector. Furthermore, in the case of the lack of an analyzer grating, the shifting curves are still existent in theory as long as the number of fringes is non-integral in a detector pixel, which is a sufficient condition for creating shifting curve. The sufficient condition is available for not only the Talbot–Lau interferometer and the inverse geometry of Talbot–Lau interferometer, but also the x-ray phase contrast imaging system based on geometrical optics. In practical applications, we propose a method to improve the performances of the existing systems by employing the sufficient condition. This method can shorten the system length, is applicable to large period gratings, and can use the detectors with large pixels and large field of view. In addition, the experimental arrangement can be simplified due to the lack of an analyzer grating. In order to improve detection sensitivity and resolution, we also give an optimal fringe period.We believe that the theory and method proposed here is a step forward for x-ray phase contrast imaging.
基金Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KJCX2-YW-N42)the Key Project of the National Natural Science Foundation of China (Grant No.10734070)+3 种基金the National Natural Science Foundation of China (Grant No.11205157)the National Basic Research Program of China (Grant Nos. 2009CB930804 and 2012CB825800)the Fundamental Research Funds for the Central Universities,China (Grant No. WK2310000021)the China Postdoctoral Science Foundation (Grant No. 2011M501064)
文摘Grating-based X-ray phase contrast imaging has been demonstrated to he an extremely powerful phase-sensitive imaging technique. By using two-dimensional (2D) gratings, the observable contrast is extended to two refraction directions. Recently, we have developed a novel reverse-projection (RP) method, which is capable of retrieving the object information efficiently with one-dimensional (1D) grating-based phase contrast imaging. In this contribution, we present its extension to the 2D grating-based X-ray phase contrast imaging, named the two-dimensional reverse- projection (2D-RP) method, for information retrieval. The method takes into account the nonlinear contributions of two refraction directions and allows the retrieval of the absorption, the horizontal and the vertical refraction images. The obtained information can be used for the reconstruction of the three-dimensionak phase gradient field, and for an improved phase map retrieval and reconstruction. Numerical experiments are carried out, and the results confirm the validity of the 2D-RP method.
基金Supported by the National Natural Science Foundation of China(No.11105213)the State Key Development Program for Basic Research of China(No.2010CB834301)+1 种基金the External Cooperation Program of the Chinese Academy of Sciences(No.GJHZ09058)the Knowledge Innovation Program of the Chinese Academy of Sciences
文摘With the spatial coherence of X-rays and high flux and brightness of the 3rd generation synchrotron radiation facility,X-ray phase contrast microscopy(XPCM)at Shanghai Synchrotron Radiation Facility(SSRF)can provide high resolution dynamic imaging of low electron density materials in principle.In this paper,we investigated the cavitation and water-refilling processes in rice and bamboo leaves utilizing XPCM at SSRF.The occurrence of xylem cavitation was recorded in vivo.The study also revealed that under different dehydration conditions,cavitation occurs in different degrees,and therefore,the refilling process is different.The results demonstrate that SSRF can provide high enough fluxes to study dynamic processes in plants in real-time,and XPCM is expected to be a promising method to reveal the mechanisms of cavitation and its repair in plants nondestructively.
文摘X-ray in-line phase contrast imaging enables weakly to absorb specimens to be imaged successfully with high resolution and definition. In this paper we use computer simulation method to analyze how each parameter influences the quality of the image. It can avoid wasting unnecessary time and materials in the course of experiment to get ideal images.
基金Project supported by LingChuang Research Project of China National Nuclear Corporationthe National Natural Science Foundation of China(Grant No.12027812)。
文摘Dual-phase and three-phase grating x-ray interference is a promising new technique for grating-based x-ray differential phase contrast imaging.Dual-phase grating interferometers have been relatively completely studied and discussed.In this paper,the corresponding imaging fringe formula of the three-phase grating interferometer is provided.At the same time,the similarities and differences between the three-phase grating interferometer and the dual-phase grating interferometer are investigated and verified,and that the three-phase grating interferometer can produce large-period moiréfringes without using the analyzing grating is demonstrated experimentally.Finally,a simple method of designing three-phase grating and multi-grating imaging systems from geometric optics based on the thin-lens theory of gratings is presented.These theoretical formulas and experimental results provide optimization tools for designing three-phase grating interferometer systems.
基金supported by the National Key Research and Development Program of China(Nos.2019YFE03090100 and 2022YFE03100002)National Natural Science Foundation of China(No.12075241)。
文摘The optical design of near-infrared phase contrast imaging(NI-PCI)diagnosis on HL-2A is introduced in this paper.This scheme benefits from the great progress of near-infrared laser technology and is a broadening of traditional phase contrast technology.This diagnostic can work as a keen tool to measure plasma wavenumber spectra by inferring string-integrated plasma density fluctuations.Design of both the front optical path which is the path before the laser transmitting into the tokamak plasma and the rear optics which is the path after the laser passing through the plasma is detailed.The 1550 nm laser is chosen as the probe beam and highprecision optical components are designed to fit the laser beam,in which a phase plate with a 194-nm-deep silver groove is the key.Compared with the conventional 10.6μm laser-based PCI system on HL-2A,NI-PCI significantly overcomes the unwanted phase scintillation effect and promotes the measurement capability of high-wavenumber turbulence with an increased maximal measurable wavenumber from 15 cm^(-1)to 32.6 cm^(-1).
基金supported in part by the National Natural Science Foundation of China(NSFC)under Grants 11275019,21106158 and 61077011in part by the National State Key Laboratory of Multiphase Complex Systems under Grant MPCS-2011-D-03+4 种基金in part by the National Key Technology R&D Program of China under Grant 2011 BAI02B02supported in part by the National Research Foundation of Korea(NRF)grantfunded by the Korean government(MEST)(No.2011-0020024)in part by the R&D program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korean government Ministry of Knowledge Economy(No.20101020300730)the Defense Acquisition Program Administration and the Agency for Defense Development for the financial support provided by both institutions
文摘TRISO (tristructural-isotropic) fuel is a type of micro fuel particles used in high-temperature gas-cooled reactors (HTGRs). Among the quality evaluation methods for such particles, inqine phase contrast imaging technique (PCI) is more feasible for nondestructive measurement. Due to imaging hardware limitations, high noise level is a distinct feature of PCI images, and as a result, the dimensional measurement accuracy of TRISO-coated fuel particles decreases. Therefore, we propose an improved denoising hybrid model named as NL P-M model which introduces non-local theory and retains the merits of the Perona-Malik (P-M) model. The improved model is applied to numerical simulation and practical PCI images. Quanti- tative analysis proves that this new anisotropic diffusion model can preserve edge or texture information effectively, while ruling out noise and distinctly decreasing staircasing artifacts. Especially during the process of coating layer thickness measurement, the NL P-M model makes it easy to obtain continuous contours without noisy points or fake contour segments, thus enhancing the measurement accuracy. To address calculation complexity, a graphic processing unit (GPU) is adopted to realize the acceleration of the NL P-M denoising.
基金supported by the National Natural Science Foundation of China(Grant Nos.11275204,11475175,and 11405175)the China Postdoctoral Science Foundation(Grant No.2017M612097)the Fundamental Research Funds for the Central Universities(Grant No.WK2310000065)
文摘X-ray grating interferometer has attracted widely attention in the past years due to its capability in achieving x-ray phase contrast imaging with low brilliance source. However, the widely used phase stepping information extraction method reduces system stability and prolongs data acquisition time by several times compared with conventional x-ray absorption- based imaging. The mechanical stepping can be avoided by using a staggered grating, but at the cost of low vertical spatial resolution. In this paper, employing a modified staggered grating and the angular signal radiography, we proposed a single-shot grating-based x-ray differential phase contrast imaging with decent vertical spatial resolution. The theoretical framework was deduced and proved by numerical experiments. Absorption, phase, and scattering computed tomography can be performed without phase stepping. Therefore, we believe this fast and highly stable imaging method with decent resolution would be widely applied in x-ray grating-based phase contrast imaging.
基金sponsored by the Helmholtz Association,the China Scholarship Council(CSC)partially funded by the German Research Foundation,DFG(Project No.MA 5039/4-1)。
文摘Tin(Sn)holds great promise as an anode material for next-generation lithium(Li)ion batteries but suffers from massive volume change and poor cycling performance.To clarify the dynamic chemical and microstructural evolution of Sn anode during lithiation and delithiation,synchrotron X-ray energydispersive diffraction and X-ray tomography are simultaneously employed during Li/Sn cell operation.The intermediate Li-Sn alloy phases during de/lithiation are identified,and their dynamic phase transformation is unraveled which is further correlated with the volume variation of the Sn at particle-and electrode-level.Moreover,we find that the Sn particle expansion/shrinkage induced particle displacement is anisotropic:the displacement perpendicular to the electrode surface(z-axis)is more pronounced compared to the directions(x-and y-axis)along the electrode surface.This anisotropic particle displacement leads to an anisotropic volume variation at the electrode level and eventually generates a net electrode expansion towards the separator after cycling,which could be one of the root causes of mechanical detachment and delamination of electrodes during long-term operation.The unraveled chemical evolution of Li-Sn and deep insights into the microstructural evolution of Sn anode provided here could guide future design and engineering of Sn and other alloy anodes for high energy density Li-and Na-ion batteries.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60232090 and 10774102)the Science & Technology Project from Shenzhen Government of China (Grant Nos. 2008340 and 200717)
文摘An x-ray scintillator screen with a special structure, functioning as detector and analyser grating, was proposed for collecting the interferogram of differential phase contrast imaging without absorption grating and difficulty of fabrication by a state of the art technique. On the basis of phase grating diffraction, a detecting model of the scintillator screen was built for analysing the phase and absorption information of objects. According to the analysis, a new method of phase retrievals based on two-images and the optimal structure of screen were presented.
文摘BACKGROUND Many imaging methods such as ultrasonography,computed tomography(CT),magnetic resonance imaging,and endoscopy are used to identify the problems or complications that occur in the perioperative period and to determine the appropriate therapeutic approach.Specialists at surgical clinics and intensive care units sometimes need diagnostic procedures that can give quick results or reveal unexpected results.In particular,rapid on-site evaluation of patients followed under intensive care conditions has several advantages.AIM To determine the problems developing in patients in the perioperative period by contrast-enhanced abdominal X-ray(CE-AXR),revealing their current status or defining the effectiveness of CE-AXR.METHODS The files of the patients who underwent hepatopancreatobiliary or upper gastrointestinal surgery,whose CE-AXR film was taken,were reviewed retrospectively.Abdominal X-ray radiographs taken after ingestion of a watersoluble contrast agent(iohexol,300 mg,50 cc vial)and its application in a drain,nasogastric tube,or stent were evaluated.The contribution of the data obtained in patients who underwent CE-AXR to the diagnosis,follow-up,and treatment processes and the effectiveness of the application were investigated.RESULTS CE-AXR was applied to 131 patients in our clinic,most of whom underwent hepatopancreatobiliary or upper gastrointestinal surgery.It was determined that the data obtained from CE-AXR films taken in 98(74.8%)of the patients contributed to the diagnosis,treatment,and follow-up expectations and positively affected the clinical processes.CONCLUSION CE-AXR is a simple procedure that can be applied anywhere,especially in intensive care patients and at bedside,with a portable X-ray device.The simplicity of the procedure,less radiation exposure for the patients,less time wastage,reduction in the CT and endoscopy procedure burden and costs,quick results,rapid assessment of the situation,and enabling the monitoring of processes with repetitive procedures are important advantages.X-rays taken will be useful in terms of being a reference value during the follow-up period of the patient and determining the situation in medicolegal processes.
基金Supported by National Basic Research Program of China (973 Program Grant No.2010CB834305)
文摘Imaging blood vessels is of importance for determining the vascular distribution of organs and tumors.Phase-contrast X-ray imaging can reveal the vessels in much more detail than conventional X-ray absorption method.Visualizing murine liver microvasculature ex vivo with phase-contrast X-ray imaging was performed at Shanghai Synchrotron Radiation Facility.Barium sulfate and physiological saline were used as contrast agents for the blood vessels.Blood vessels of <Φ20μm could be detected by replacing resident blood with physiological saline or barium sulfate.An entire branch of the portal vein (from the main axial portal vein to the ninth generation of branching) could be captured in a single phase-contrast image.It is demonstrated that selective angiography based on phase contrast X-ray imaging,with a physiological material of low Z elements (such as saline) being the contrast agent,is a viable imaging strategy.Further efforts will be focused on using the technique to image tumor angiogenesis.
基金National Natural Science Foundation of China(No.10275087)Shanghai Foundation on Development of Science and Technology(No.022261023) Shanghai Foundation for Natural Science(No.02ZF14116)
文摘An experimental study on nondestructive X-ray imaging of inner structure of soft tissues in phase con-trast has been conducted with Beijing Synchrotron Radiation Facility (BSRF). Modification to the beamline setupwas made to enlarge the X-ray beam section and consequently larger samples could be imaged. In-line setup was em-ployed for experiments. Results on a series of samples were given and soft-tissue details of less than 50 μm inside afresh goldfish were obtained. Diagnosis of tumor in its early stage was also investigated taking SD rats as the model.Tumor at the size of ~ 100μm was observed. Potential of this technique in clinic diagnosis was discussed.
基金supported by the National Natural Science Foundation of China (Grant No.12072331)the Science Challenge Project (Grant No.TZ2018001)+2 种基金the Japan Society for the Promotion of Science (Grant Nos.17H04820 and 21H01677)the Foundation of the United Laboratory of High-Pressure Physics and Earthquake Scienceperformed under the approval of the Photon Factory Program Advisory Committee (Proposal Nos.2016S2-006 and 2020G680)。
文摘A time-resolved x-ray diffraction technique is employed to monitor the structural transformation of laser-shocked bismuth.Results reveal a retarded transformation from the shock-induced Bi-Ⅴphase to a metastable Bi-Ⅳphase during the shock release,instead of the thermodynamically stable Bi-Ⅲphase.The emergence of the metastable Bi-Ⅳphase is understood by the competitive interplay between two transformation pathways towards the Bi-Ⅳand Bi-Ⅲ,respectively.The former is more rapid than the latter because the Bi-Ⅴto B-Ⅳtransformation is driven by interaction between the closest atoms while the Bi-Ⅴto B-Ⅲtransformation requires interaction between the second-closest atoms.The nucleation time for the Bi-Ⅴto Bi-Ⅳtransformation is determined to be 5.1±0.9 ns according to a classical nucleation model.This observation demonstrates the importance of the formation of the transient metastable phases,which can change the phase transformation pathway in a dynamic process.
基金financially supported by the National Natural Science Foundation of China(Grant No.62074089)the Natural Science Foundation of Ningbo City,China(Grant No.2022J072)+1 种基金the Youth Science and Technology Innovation Leading Talent Project of Ningbo City,China(Grant No.2023QL005)sponsored by the K.C.Wong Magna Fund in Ningbo University。
文摘The amorphous phase-change materials with spontaneous structural relaxation leads to the resistance drift with the time for phase-change neuron synaptic devices. Here, we modify the phase change properties of the conventional Ge_2Sb_2Te_5(GST) material by introducing an SnS phase. It is found that the resistance drift coefficient of SnS-doped GST was decreased from 0.06 to 0.01. It can be proposed that the origin originates from the precipitation of GST nanocrystals accompanied by the precipitation of SnS crystals compared to single-phase GST compound systems. We also found that the decrease in resistance drift can be attributed to the narrowed bandgap from 0.65 to 0.43 eV after SnS-doping. Thus, this study reveals the quantitative relationship between the resistance drift and the band gap and proposes a new idea for alleviating the resistance drift by composition optimization, which is of great significance for finding a promising phase change material.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61101175,61571305,and 61227802)
文摘A fast and simple method to extract phase-contrast images from interferograms is proposed, and its effectiveness is demonstrated through simulation and experiment. For x-ray differential phase contrast imaging, a strong attenuation signal acts as an overwhelming background intensity that obscures the weak phase signal so that no obvious phase-gradient information is detectable in the raw image. By subtracting one interferogram from another, chosen at particular intervals,the phase signal can be isolated and magnified.
基金Project supported by the National Natural Science Foundation of China (Grant No 10475044).
文摘In-line x-ray phase contrast imaging has attracted much attention due to two major advantages: its effectiveness in imaging weakly absorbing materials, and the simplicity of its facilities. In this paper a comprehensive theory based on Wigner distribution developed by Wu and Liu [Med. Phys. 31 2378-2384 (2004)] is reviewed. The influence of x-ray source and detector on the image is discussed. Experiments using a microfocus x-ray source and a CCD detector are conducted, which show the role of two key factors on imaging: the tube voltage and tube current. High tube current and moderate tube voltage are suggested for imaging.
基金Project supported by the National Natural Science Foundation of China (Grant No 10475044).
文摘For weakly absorbing materials, image contrast can be enhanced by phase contrast in formation. The effectiveness of the in-line phase contrast technique relies on its ability to record intensity data which contain information on the x- ray's phase shift. Four kinds of approaches to the relationship between intensity distribution and phase shift axe reviewed and discussed. A micro-focal x-ray source with high geometrical magnification is used to acquire phase contrast images. A great improvement on image quality is shown and geometrical parameters axe modified for comparison between different imaging positions.
基金Project supported by the National Basic Research P.rogram of China (No.2003CB716101)the National Natural Science Foundation of China (No.60532080)+1 种基金the Science Foundation of Chinese Ministry of Education(No.306017)the Science Foundation of Engineering Research Institute of Peking University,and the Science Foundation of Microsoft Research of Asia.
文摘A new algorithm for phase contrast X-ray tomography under holographic measurement was proposed in this paper. The main idea of the algorithm was to solve the nonlinear phase retrieval problem using the Newton iterative method. The linear equations for the Newton directions were proved to be ill-posed and the regularized solutions were obtained by the conjugate gradient method. Some numerical experiments with computer simulated data were presented. The efficiency, feasibility and the numerical stability of the algorithm were illustrated by the numerical experiments. Compared with the results produced by the linearized phase retrieval algorithm, we can see that the new algorithm is not limited to be only efficient for the data measured in the near-field of the Fresnel region and thus it has a broader validity range.
基金Project supported by the National Natural Science Foundation of China(Grant No.61405144)the Natural Science Foundation of Tianjin,China(Grant No.15JCQNJC42100)the Technology Special Commissioner Project of Tianjin,China(Grant Nos.16JCTPJC47200 and 16JCTPJC48100)
文摘The principle of dual-energy x-ray grating phase-contrast imaging(DEPCI) is clarified by using the theory of x-ray interference and Fresnel diffraction. A new method of retrieving phase from the two interferograms is proposed for DEPCI,and its feasibility is verified via simulation. Finally, the proposed method applied to DEPCI experiment demonstrates the effectiveness of the method. This paper lays the theoretical foundation for performance optimization of DEPCI and the further integration of DEPCI and computed tomography.