X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of sample...X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus beating tremendous potential for future clinical diagnosis. In this work, by changing the accel- erating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer （located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan） versus tube voltage. Ex- perimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ~ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum.展开更多
A penetrating view of the three-dimensional nanostructure of female spermatheca and male flagellum in the species Aleochara verna is obtained with 100-nm resolution using a hard X-ray microscope, which provides a fast...A penetrating view of the three-dimensional nanostructure of female spermatheca and male flagellum in the species Aleochara verna is obtained with 100-nm resolution using a hard X-ray microscope, which provides a fast noninvasive imaging technology for insect morphology. Through introducing Zernike phase contrast and heavy metal staining, images taken at 8 keV displayed sufficient contrast for observing nanoscale fine structures, such as the spermatheca cochleate duct and the subapex of the flagellum, which have some implications for the study of the sperm transfer process and genital evolution in insects. This work shows that both the spatial resolution and the contrast characteristic of hard X-ray microscopy are quite promising for insect morphology studies and, particularly, provide an attractive alternative to the destructive techniques used for investigating internal soft tissues.展开更多
Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object ...Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object in the beam. In this paper, the authors perform a full comparative analysis and present the main virtues and limitations of these two methods according to the theoretical analysis of the grating interferometry.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
The relationship between noise variance and spatial resolution in grating-based x-ray phase computed tomography（PCT） imaging is investigated with reverse projection extraction method, and the noise variances of the ...The relationship between noise variance and spatial resolution in grating-based x-ray phase computed tomography（PCT） imaging is investigated with reverse projection extraction method, and the noise variances of the reconstructed absorption coefficient and refractive index decrement are compared. For the differential phase contrast method, the noise variance in the differential projection images follows the same inverse-square law with spatial resolution as in conventional absorption-based x-ray imaging projections. However, both theoretical analysis and simulations demonstrate that in PCT the noise variance of the reconstructed refractive index decrement scales with spatial resolution follows an inverse linear relationship at fixed slice thickness, while the noise variance of the reconstructed absorption coefficient conforms with the inverse cubic law. The results indicate that, for the same noise variance level, PCT imaging may enable higher spatial resolution than conventional absorption computed tomography（ACT）, while ACT benefits more from degraded spatial resolution. This could be a useful guidance in imaging the inner structure of the sample in higher spatial resolution.展开更多
A new method in diffraction-enhanced imaging computed tomography （DEI-CT） that follows the idea developed by Chapman et al. [Chapman D, Thomlinson W, Johnston R E, Washburn D, Pisano E, Gmur N, Zhong Z, Menk R, Arfe...A new method in diffraction-enhanced imaging computed tomography （DEI-CT） that follows the idea developed by Chapman et al. [Chapman D, Thomlinson W, Johnston R E, Washburn D, Pisano E, Gmur N, Zhong Z, Menk R, Arfelli F and Sayers D 1997 Phys. Med. BioL 42 2015] in 1997 is proposed in this paper. Merged with a ＂reverse projections＂ algorithm, only two sets of projection datasets at two defined orientations of the analyzer crystal are needed to reconstruct the linear absorption coefficient, the decrement of the real part of the refractive index and the linear scattering coefficient of the sample. Not only does this method reduce the delivered dose to the sample without degrading the image quality, but, compared with the existing DEI-CT approaches, it simplifies data-acquisition procedures. Experimental results confirm the reliability of this new method for DEI-CT applications.展开更多
In this work, we extensively describe and demonstrate the structured dark-field imaging(SDFI). SDFI is a newly proposed x-ray microscopy designed for revealing the fine features below Rayleigh resolution, in which dif...In this work, we extensively describe and demonstrate the structured dark-field imaging(SDFI). SDFI is a newly proposed x-ray microscopy designed for revealing the fine features below Rayleigh resolution, in which different orders of scattered x-ray photons are collected by changing the numerical aperture of the condenser. Here, the samples of single particles are discussed to extend the scope of the SDFI technique reported in a previous work(Chen J, Gao K, Ge X, et al.2013 Opt. Lett. 38 2068). In addition, the details of the newly invented algorithm are explained, which is able to calculate the intensity of any pixel on the image plane rapidly and reliably.展开更多
In this paper neutron diffraction experiments were performed for Fe-substituted Mn12 in order to determine the sites of Fe atoms. The results of structure refinements for the sample with our accessed highest Fe conten...In this paper neutron diffraction experiments were performed for Fe-substituted Mn12 in order to determine the sites of Fe atoms. The results of structure refinements for the sample with our accessed highest Fe content showed that all Fe atoms occupied Mn（3） sites in the Mn12 skeleton. The x-ray absorption fine structure experiments as well as multiple scattering simulations gave the same result. Thus we concluded that Fe atoms only occupied Mn（3） sites. This conclusion also means that Fe-substituted Mn12 series only includes the four single-molecule magnets of [Mn12-xFexO12（CH3COO）16（H2O）4]·2CH3COOH·4H2O （x = 1, 2, 3, and 4）, denoted by Mn11Fe1, Mn10Fe2, MngFe3, and Mn8Fe4, respectively.展开更多
We propose a method for reconstructing a complex field from a series of its near-field diffraction patterns.This method is based on the paraxial Fresnel diffraction equation without making further approximations.Numer...We propose a method for reconstructing a complex field from a series of its near-field diffraction patterns.This method is based on the paraxial Fresnel diffraction equation without making further approximations.Numerical simulations are presented showing that a complex field can even be reconstructed with moderate qualities from its two near-field diffraction patterns and almost exact reconstructions can be obtained when three or more diffraction patterns are used.We also show by numerical simulation that the correct diffraction distances can be recovered in case only coarsely measured values are available.This method may be applied to phase imaging of weak-absorption objects.展开更多
基金Project supported by the Major State Basic Research Development Program of China(Grant No.2012CB825800)the Science Fund for Creative Research Groups,China(Grant No.11321503)+1 种基金the National Natural Science Foundation of China(Grant Nos.11179004,10979055,11205189,and 11205157)the Japan–Asia Youth Exchange Program in Science(SAKURA Exchange Program in Science)Administered by the Japan Science and Technology Agency
文摘X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus beating tremendous potential for future clinical diagnosis. In this work, by changing the accel- erating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer （located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan） versus tube voltage. Ex- perimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ~ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum.
基金the National Basic Research Program of China(Grant Nos.2012CB825800 and 2009CB930804)the Key Program of the National Natural Science Foundation of China(Grant Nos.10734070 and 10774144)+1 种基金the National Natural Science Foundation of China(Grant Nos.11205189,10979055,31071909,and 31272358)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-YW-N42)
文摘A penetrating view of the three-dimensional nanostructure of female spermatheca and male flagellum in the species Aleochara verna is obtained with 100-nm resolution using a hard X-ray microscope, which provides a fast noninvasive imaging technology for insect morphology. Through introducing Zernike phase contrast and heavy metal staining, images taken at 8 keV displayed sufficient contrast for observing nanoscale fine structures, such as the spermatheca cochleate duct and the subapex of the flagellum, which have some implications for the study of the sperm transfer process and genital evolution in insects. This work shows that both the spatial resolution and the contrast characteristic of hard X-ray microscopy are quite promising for insect morphology studies and, particularly, provide an attractive alternative to the destructive techniques used for investigating internal soft tissues.
基金Project supported by the Key Program of the National Natural Science Foundation of China(Grant Nos.10490194 and 10734070) the National Natural Science Foundation of China(Grant Nos.10504033,10774144 and 10979055)+2 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-YW-N42)the National Basic Research Program of China (Grant No.2009CB930804)the National Outstanding Youth Fund(Grant No.10125523)
文摘Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object in the beam. In this paper, the authors perform a full comparative analysis and present the main virtues and limitations of these two methods according to the theoretical analysis of the grating interferometry.
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Project supported by the National Basic Research Program of China(Grant No.2012CB825800)the Science Fund for Creative Research Groups,the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KJCX2-YW-N42 and Y4545320Y2)the National Natural Science Foundation of China(Grant Nos.11475170,11205157,11305173,11205189,11375225,11321503,11179004,and U1332109)
文摘The relationship between noise variance and spatial resolution in grating-based x-ray phase computed tomography（PCT） imaging is investigated with reverse projection extraction method, and the noise variances of the reconstructed absorption coefficient and refractive index decrement are compared. For the differential phase contrast method, the noise variance in the differential projection images follows the same inverse-square law with spatial resolution as in conventional absorption-based x-ray imaging projections. However, both theoretical analysis and simulations demonstrate that in PCT the noise variance of the reconstructed refractive index decrement scales with spatial resolution follows an inverse linear relationship at fixed slice thickness, while the noise variance of the reconstructed absorption coefficient conforms with the inverse cubic law. The results indicate that, for the same noise variance level, PCT imaging may enable higher spatial resolution than conventional absorption computed tomography（ACT）, while ACT benefits more from degraded spatial resolution. This could be a useful guidance in imaging the inner structure of the sample in higher spatial resolution.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB825800)the National Natural Science Foundation of China(Grant Nos.11205189,11375225,and U1332109)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KJCX2-YW-N42,Y4545320Y2,and 542014IHEPZZBS50659)
文摘A new method in diffraction-enhanced imaging computed tomography （DEI-CT） that follows the idea developed by Chapman et al. [Chapman D, Thomlinson W, Johnston R E, Washburn D, Pisano E, Gmur N, Zhong Z, Menk R, Arfelli F and Sayers D 1997 Phys. Med. BioL 42 2015] in 1997 is proposed in this paper. Merged with a ＂reverse projections＂ algorithm, only two sets of projection datasets at two defined orientations of the analyzer crystal are needed to reconstruct the linear absorption coefficient, the decrement of the real part of the refractive index and the linear scattering coefficient of the sample. Not only does this method reduce the delivered dose to the sample without degrading the image quality, but, compared with the existing DEI-CT approaches, it simplifies data-acquisition procedures. Experimental results confirm the reliability of this new method for DEI-CT applications.
基金supported by the National Basic Research Program of China(Grant No.2012CB825800)the Science Fund for Creative Research Groups,the National Natural Science Foundation of China(Grant Nos.11475170,11205157,11305173,and 11321503)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-YW-N42)
文摘In this work, we extensively describe and demonstrate the structured dark-field imaging(SDFI). SDFI is a newly proposed x-ray microscopy designed for revealing the fine features below Rayleigh resolution, in which different orders of scattered x-ray photons are collected by changing the numerical aperture of the condenser. Here, the samples of single particles are discussed to extend the scope of the SDFI technique reported in a previous work(Chen J, Gao K, Ge X, et al.2013 Opt. Lett. 38 2068). In addition, the details of the newly invented algorithm are explained, which is able to calculate the intensity of any pixel on the image plane rapidly and reliably.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10375088 and 10505029）. Acknowledgment The authors thank Dr Denis Sheptyakov at PSI for much support of the neutron diffraction experiments.
文摘In this paper neutron diffraction experiments were performed for Fe-substituted Mn12 in order to determine the sites of Fe atoms. The results of structure refinements for the sample with our accessed highest Fe content showed that all Fe atoms occupied Mn（3） sites in the Mn12 skeleton. The x-ray absorption fine structure experiments as well as multiple scattering simulations gave the same result. Thus we concluded that Fe atoms only occupied Mn（3） sites. This conclusion also means that Fe-substituted Mn12 series only includes the four single-molecule magnets of [Mn12-xFexO12（CH3COO）16（H2O）4]·2CH3COOH·4H2O （x = 1, 2, 3, and 4）, denoted by Mn11Fe1, Mn10Fe2, MngFe3, and Mn8Fe4, respectively.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2012CB825800 and 2009CB930804)the Key Important Project of the National Natural Science Foundation of China (Grant No. 10734070)+1 种基金the National Natural Science Foundation of China (Grant Nos. 11179004 and 10979055)the Knowledge Innovation Program of the Chinese Academy ofSciences (Grant No. KJCX2-YW-N42)
文摘We propose a method for reconstructing a complex field from a series of its near-field diffraction patterns.This method is based on the paraxial Fresnel diffraction equation without making further approximations.Numerical simulations are presented showing that a complex field can even be reconstructed with moderate qualities from its two near-field diffraction patterns and almost exact reconstructions can be obtained when three or more diffraction patterns are used.We also show by numerical simulation that the correct diffraction distances can be recovered in case only coarsely measured values are available.This method may be applied to phase imaging of weak-absorption objects.
