bluuebunny/crossref_metadata_2025 huggingface dataset:
In vivo mouse ^{99m}Tc SPECT	scans with bioluminescence imaging validation
Authors: Liang Zhi-Xin , Qiang Yong-Gang , Liao Yong-Hua , Zhu Xu-Sheng , Huang Zheng , Zhang Xiu-Ping , Wang Luping
Published: December 2019

The aim of this in vivo study was to evaluate the feasibility of ^{99m} Tc-labeled cartilage link protein (CLP) probe for the single-photon emission computed tomography (SPECT) of lung cancer. Xenograft mouse model were established from a luciferase expressing cell line derived from a human lung cancer. Bioluminescence imaging (BLI) was carried out prior to ^{99m} Tc-CLP and ^{99m} Tc-methoxyisobutyl isonitrile (MIBI) SPECT scans. The image quality of ^{99m} Tc-CLP scan was validated with BLI and compared with well established ^{99m} Tc-MIBI scan. Results of multimodal imaging analyses suggested that ^{99m} Tc-CLP was a sensitive and reliable SPECT agent for lung cancer imaging.
Quantitative flow measurement by digital subtraction angiography	in cerebral carotid stenosis using optical flow method
Authors: Huang Tzung-Chi , Wu Tung-Hsin , Lin Yang-Hsien , Guo Wan-Yuo , Huang Wei-Chien , Lin Chung-Jung
Published: December 2019

OBJECTIVE: We analyzed intracranial regional blood flows using an optical flow method (OFM) and digital subtraction angiography in patients with internal carotid artery (ICA) stenosis. We also retrospectively explored the correlation between the patients' diagnoses and the severity of the ICA stenoses.

MATERIALS AND METHODS: OFM, an image-processing algorithm to estimate motion, was applied to determine the mean velocity V $_{mean}$ in the vessels. A group of 40 patients without vascular anomalies acted as the control group. The patients were classified as having either moderate stenosis (< 80%, n=14) or severe stenosis (> 80%, n=23).

RESULTS: The V $_{mean}$ of the ICAs was significantly lower in the stenotic group compared with the control group (p< 0.01). The V $_{mean}$ of the ICAs was inversely correlated with the severity of the stenosis (p< 0.05). The receiver operating characteristic curve of the V $_{mean}$ in an AP view showed substantial discriminatory power, with an optimal cutoff value of 3.48 pixels/frame for the detection of patients with carotid stenosis. The sensitivity and specificity were 84% and 50%, respectively. On a lateral view, the best cutoff for the V $_{mean}$ was 4.01 pixels/frame, and the sensitivity and specificity were 92% and 43%, respectively.

CONCLUSIONS: Digital subtraction angiography combined with the OFM is a feasible parametric method for intracranial blood flow measurements in patients with moderate to severe carotid stenosis.
An algorithm for 4D CT image sorting using spatial continuity
Authors: Li Chen , Liu Jie
Published: December 2019

4D CT, which could locate the position of the movement of the tumor in the entire respiratory cycle and reduce image artifacts effectively, has been widely used in making radiation therapy of tumors. The current 4D CT methods required external surrogates of respiratory motion obtained from extra instruments. However, respiratory signals recorded by these external makers may not always accurately represent the internal tumor and organ movements, especially when irregular breathing patterns happened. In this paper we have proposed a novel automatic 4D CT sorting algorithm that performs without these external surrogates. The sorting algorithm requires collecting the image data with a cine scan protocol. Beginning with the first couch position, images from the adjacent couch position are selected out according to spatial continuity. The process is continued until images from all couch positions are sorted and the entire 3D volume is produced. The algorithm is verified by respiratory phantom image data and clinical image data. The primary test results show that the 4D CT images created by our algorithm have eliminated the motion artifacts effectively and clearly demonstrated the movement of tumor and organ in the breath period.
Suprapubic-assisted umbilical laparoendoscopic mini-dual-site	surgery in the treatment of simple kidney cyst: Report of 26 cases
Authors: Luo Daosheng , Liu Guihua , Mo Junhua , Xiao Lihua , Xie Qiang , Li Mu , Zhang Zengqiang , Lu Jianjun , Liang Zhenfeng , Meng Xiangjun , Zhang Yuanyuan , Deng Chunhua , Mi Qiwu
Published: December 2019

This study was designed to evaluate the safety and efficacy of suprapubic-assisted umbilical laparoendoscopic mini-dual-site surgery (SAU-LEMDS) with satisfied cosmetic outcome in minimal size of surgical incision for the treatment of simple kidney cyst at large size. Twenty-six consecutive patients (16 male and 10 female), aged 48.5 ± 4.1 years (range: 18 to 70 years), were enrolled in this study. All cases had simple kidney cysts including 18 cases on the left side and 8 cases on the right, with a mean cyst maximum diameter of 7.5 ± 0.8 cm. Under general anesthesia, the patients were placed in flank position with affected side elevated by 70°. Two trocars (5.5 mm in diameter) were inserted via the umbilical port. The third trocar was inserted into abdominal cavity above the pubic hairline for the placement of a 5-mm 30° laparoscope. The surgery procedures were successfully performed in the same manner as standard laparoscope-assisted kidney cyst decortication in all cases. The specimens were obtained through either of two umbilical ports without additional enlarge incisions. The mean operation time was 30 ± 8.2 min and the mean blood loss was 10.3 ± 2.1 ml. The duration of hospitalization was 4.2 ± 0.9 days, and the mean follow-up was two months (range: 1 to 3 months). Postoperatively, surgical wounds were small and healed well and cosmetic outcomes were satisfactory. No recurrent kidney cysts were found during follow up. SAU-LEMDS appears to be a feasible, safe and effective surgical option for simple kidney cyst, which not only leads to better cosmetic effects, but also decreases the complexity of umbilical laparoendoscopic single site surgery (U-LESS).
X-ray strain tensor imaging: FEM simulation and experiments with a micro-CT
Authors: Kim Jae G. , Park So E. , Lee Soo Y.
Published: December 2019

In tissue elasticity imaging, measuring the strain tensor components is necessary to solve the inverse problem. However, it is impractical to measure all the tensor components in ultrasound or MRI elastography because of their anisotropic spatial resolution. The objective of this study is to compute 3D strain tensor maps from the 3D CT images of a tissue-mimicking phantom. We took 3D micro-CT images of the phantom twice with applying two different mechanical compressions to it. Applying the 3D image correlation technique to the CT images under different compression, we computed 3D displacement vectors and strain tensors at every pixel. To evaluate the accuracy of the strain tensor maps, we made a 3D FEM model of the phantom, and we computed strain tensor maps through FEM simulation. Experimentally obtained strain tensor maps showed similar patterns to the FEM-simulated ones in visual inspection. The correlation between the strain tensor maps obtained from the experiment and the FEM simulation ranges from 0.03 to 0.93. Even though the strain tensor maps suffer from high level noise, we expect the x-ray strain tensor imaging may find some biomedical applications such as malignant tissue characterization and stress analysis inside the tissues.
Optimizing contrast agents with respect to reducing beam hardening	in nonmedical X-ray computed tomography experiments
Authors: Nakashima Yoshito , Nakano Tsukasa
Published: December 2019

Iodine is commonly used as a contrast agent in nonmedical science and engineering, for example, to visualize Darcy flow in porous geological media using X-ray computed tomography (CT). Undesirable beam hardening artifacts occur when a polychromatic X-ray source is used, which makes the quantitative analysis of CT images difficult. To optimize the chemistry of a contrast agent in terms of the beam hardening reduction, we performed computer simulations and generated synthetic CT images of a homogeneous cylindrical sand-pack (diameter, 28 or 56 mm; porosity, 39 vol.% saturated with aqueous suspensions of heavy elements assuming the use of a polychromatic medical CT scanner. The degree of cupping derived from the beam hardening was assessed using the reconstructed CT images to find the chemistry of the suspension that induced the least cupping. The results showed that (i) the degree of cupping depended on the position of the K absorption edge of the heavy element relative to peak of the polychromatic incident X-ray spectrum, (ii) $_{53}$ I was not an ideal contrast agent because it causes marked cupping, and (iii) a single element much heavier than $_{53}$ I ( $_{64}$ Gd to $_{79}$ Au) reduced the cupping artifact significantly, and a four-heavy-element mixture of elements from $_{64}$ Gd to $_{79}$ Au reduced the artifact most significantly.
A new algorithm for calculating optimal viewing angles in coronary	angiography based on 4-D cardiac computed tomography
Authors: Chen Xiaodong , Li Junwei , Zhang Zhaoxia , Wang Yi , Jia Zhongwei , Pu Kui , Yu Daoyin
Published: December 2019

BACKGROUND: Coronary stenosis is the main cause of the coronary heart disease (CHD). However, coronary arteriography (CAG), which is considered as the 'gold standard' of determining the location and severity of CHD, hardly acquires a satisfactory image for some lesions by traditional viewing angles.

OBJECTIVE: We proposed a new approach to calculate the optimal viewing angles of CAG system to observe vessel segment of interest.

METHODS: Firstly, the 4-D coronary arteries are segmented to obtain a dynamic vessel model. Then, a "rendering" method in computer graphics is used to calculate the optimal viewing angles of the vessel segment in the entire cardiac cycle. At last, an intersection of these angles can be regarded as the optimal ones in the whole cardiac cycle.

RESULTS: Within the constraint of 2% foreshortening, the single phase data show 1% foreshortening without overlapping at the optimal angles proposed by our method, compared with 1.8% foreshortening at working angles set by clinical experts. And the multi-phase experiments also have good results.

CONCLUSIONS: The new approach can provide doctors optimal viewing angles of interested vessel segment in the whole cardiac cycle.
Simulation analysis of airflow alteration in the trachea following	the vascular ring surgery based on CT images using the computational fluid	dynamics method
Authors: Chen Fong-Lin , Horng Tzyy-Leng , Shih Tzu-Ching
Published: December 2019

This study presents a computational fluid dynamics (CFD) model to simulate the three-dimensional airflow in the trachea before and after the vascular ring surgery (VRS). The simulation was based on CT-scan images of the patients with the vascular ring diseases. The surface geometry of the tracheal airway was reconstructed using triangular mesh by the Amira software package. The unstructured tetrahedral volume meshes were generated by the ANSYS ICEM CFD software package. The airflow in the tracheal airway was solved by the ESI CFD-ACE+ software package. Numerical simulation shows that the pressure drops across the tracheal stenosis before and after the surgery were 0.1789 and 0.0967 Pa, respectively, with the inspiratory inlet velocity 0.1 m/s. Meanwhile, the improvement percentage by the surgery was 45.95%. In the expiratory phase, by contrast, the improvement percentage was 40.65%. When the inspiratory velocity reached 1 m/s, the pressure drop became 4.988~Pa and the improvement percentage was 43.32%. Simulation results further show that after treatment the pressure drop in the tracheal airway was significantly decreased, especially for low inspiratory and expiratory velocities. The CFD method can be applied to quantify the airway pressure alteration and to evaluate the treatment outcome of the vascular ring surgery under different respiratory velocities.
Removing streak artifacts from ECG-gated reconstructions using	deconvolution
Authors: Mory Cyril , Auvray Vincent , Zhang Bo , Grass Michael , Schäfer Dirk , Rit Simon , Peyrin Françoise , Douek Philippe , Boussel Loïc
Published: December 2019

BACKGROUND: 4D cardiac computed tomography aims at reconstructing the beating heart from a series of 2D projections and the simultaneously acquired electrocardiogram. Each cardiac phase is reconstructed by exploiting the subset of projections acquired during this particular cardiac phase only. In these conditions, the Feldkamp, Davis and Kress method (FDK) generates large streak artifacts in the reconstructed volumes, hampering the medical interpretation. These artifacts can be substantially reduced by deconvolution methods.

OBJECTIVE: The aim of this paper is to compare two 4D cardiac CT reconstruction methods based on deconvolution, and to evaluate their practical benefits on two applications: cardiac micro CT and human cardiac C-arm CT.

METHODS: The first evaluated method builds upon inverse filtering. It has been proposed recently and demonstrated on 4D cardiac micro CT. The second one is an iterative deconvolution method, and turns out equivalent to an ECG-gated Iterative Filtered Back Projection (ECG-gated IFBP).

RESULTS: Results are presented on simulated data in 2D parallel beam, 2D fan beam and 3D cone beam geometries.

CONCLUSIONS: Both methods are efficient on the cardiac micro CT simulations, but insufficient to handle 4D human cardiac C-Arm CT simulations. Overall, ECG-gated IFPB largely outperforms the inverse filtering method.
A method of extracting structural priors from images of micro-CT	for fluorescence molecular tomography reconstruction
Authors: Meng Yuanzheng , Yang Xiaoquan , Deng Yong , Zhang Xuanxuan , Gong Hui
Published: December 2019

The dual-modality systems combined fluorescence molecular tomography (FMT) and micro-computed tomography (micro-CT) can provide molecular and anatomical information of small animals simultaneously. Except for anatomic localization, micro-CT should also offer boundary of different organs as reconstruction priors for FMT, which is more challenging than acquisition of structural information. In this paper, we propose a framework to extract structural priors of a living mouse with micro-CT. The iodinated lipid emulsion contrast agent was adopted to enhance the contrast of the soft tissues of the mouse. Then organs in thorax and abdomen were segmented with different approaches depending on the characteristics of the organs. Bone, lung, heart, liver, spleen, and muscles were separately segmented. And the results were compared with that manually segmented. The Tanimoto coefficient and the relative volume difference of segmented slices were measured to be 91.28 ± 5.78 and 0.27 ± 3.15, respectively. In our simulation study of FMT reconstruction, the errors of measured position and concentration of the fluorophore with priors declined by 89.7% and 79.6% in thorax, as well as 80.8% and 78.3% in abdomen, respectively, compared with the results without priors. The proposed scheme will make FMT reconstruction much more reliable and practical in small animal study.
Evaluation of automatic exposure control options in digital	mammography
Authors: Zhou Yifang , Scott II Alexander , Allahverdian Janet , Frankel Steve
Published: December 2019

To quantify the trade-offs of dose and image quality among pre-loaded automatic exposure control (AEC) options in digital mammography, two AEC tables from the Hologic Selenia digital mammography system were compared: the default AEC "table 0" and AEC "table 1". Realistically-shaped phantoms consisting of tissue-equivalent material of various thicknesses (4.5 cm–7 cm) were imaged to obtain a figure of merit (FOM), the squared contrast-to-noise ratio per mean glandular dose. To relate the results to pathological findings and to evaluate the overall performance, the measured contrast-to-noise ratios were applied to simulated lesions on the anthropomorphic breast phantom images, producing various lesion configurations which were blindly scored. It was found that the AEC table 1 improves the low contrast FOM by 11% to 20% for the breast thicknesses of 4.5–6 cm. However, for the 7 cm thick breast, the AEC table 1 decreases the low contrast FOM by 17%. For microcalcifications, the AEC table 1 improves the FOM slightly for the breast thicknesses of 4.5--6 cm and decreases it by 18% at a thickness of 7 cm. The lesion simulation showed enhanced contrast due to the AEC table 1 for the breast thicknesses of 5 cm, 6 cm, and 7 cm, but the enhancement gradually reduces as the thickness increases. The lesion reading showed that the microcalcification detection was scored significantly higher from the AEC table 1 for the thicknesses 5 cm, 6 cm, and 7 cm. The corresponding improvement of mass detection scores was also observed but not consistently significant over the thickness range.
Quantitative evaluation of the administrated dose affecting image	quality in myocardial perfusion SPECT
Authors: El-Gebaly Reem H. , Maamoun Islam K. , Madian Noha G.
Published: December 2019

BACKGROUND: Myocardial perfusion imaging (MPI) can provide the valuable cardiac functions.Image quality in nuclear medicine tomography is critically dependent on the activity administered into patients.

OBJECTIVE: This study was designed to evaluate the optimum injected dose of 99mTc-MIBI for quantitative assessment of image quality as compared with standard injected dose used for that purpose.

METHODS: The image quality parameters (Contrast, relative noise and contrast to noise ratio) were determined in 32 patients (21 male, 11 female, age 45–60 y) with weight 60 ± 15 kg. Patients were classified into four groups; each one consisted of 8 patients. The first group received 370 MBq, the second one received 555 MBq, the third group received 740 MBq and the last group received 925 MBq.

RESULTS: Qualitative assessments of the images revealed equivalent scintigraphic patterns in all patients. There was a significant difference in the image contrast. The image contrast in the 370 MBq group was greater than other groups. The image noise between the four groups was significantly different. It increased with injected dose reduction. Contrast to noise ratio (CNR) was significantly different between 370 MBq and other groups.

CONCLUSION: It is concluded that results from the first group which received 370 MBq are sufficiently similar to those of the fourth group (standard group) which received 925 MBq. Consequently,accurate estimations of differential cardiac functions are possible with the 370 MBq dose.
Evaluation of the dose perturbation around gold and steel fiducial	markers in a medical linac through Geant4 Monte Carlo simulation
Authors: Pontoriero Antonio , Amato Ernesto , Iatí Giuseppe , De Renzis Costantino , Pergolizzi Stefano
Published: December 2019

OBJECTIVE: Purpose of this work was to study the dose perturbation within the target volume of a external MV radiation therapy when using metal fiducials.

METHODS: We developed a Monte Carlo simulation in Geant4 of a cylindrical fiducial made either of gold or of steel and simulated the photon irradiation beam originating from a medical Linac operating at 6, 10 or 15 MV. For each energy, two different irradiation schemes were simulated: a single 5 × 5-cm square field in the -x direction, and five 5 × 5-cm fields at 0°, 80°, 165°, 195° and 280°.

RESULTS: In a single beam irradiation scheme, we observed a dose reduction behind fiducials varying from −20% for gold at 6 MV to −5% for steel at 15 MV, and a dose increment in front of the fiducial ranging from +33% for gold at 15 MV to +10% for steel at 6 MV. When five beams were employed, a dose increment ranging from +28% to +46% has been found around gold. Around a steel fiducial, an average increment of +17% was found, irrespective of the photon energy.

CONCLUSIONS: When using a single beam, the decrement of dose behind both steel and gold markers increases with the photon energy. This effect vanishes when a multifield treatment is delivered; in this instance there is a dose increment around fiducials, according to both fiducial material and photon energy, with lower values for steel and 6 MV. This energy represents the best choice when fiducial markers are present inside the irradiated volume.
A modularly designed fluorescence molecular tomography system for	multi-modality imaging
Authors: Wang Guohe , Zhang Bin , Ding Yichen , He Yun , Chen Jingsong , Lu Yanye , Jiang Xiaoyun , Shi Junwei , Bai Jing , Ren Qiushi , Li Changhui
Published: December 2019

Nowadays multi-modality imaging has gained great interest in biology research by offering complementary information. In this paper, a modularly designed fluorescence molecular tomography (FMT) system has been developed, which can be not only used as a standalone imaging device, but also feasibly integrated with other imaging modalities, such as X-ray computed tomography (X-CT), single photon emission computed tomography (SPECT) and positron emission tomography (PET), to perform multi-modality imaging in a sequential manner. The system rotates the CCD camera and the excitation light source in the vertical plane, while the animal is stationed on a horizontally moveable transparent animal holder at its natural prone position. FMT and other imaging modalities are co-registered automatically. Phantom and animal experiments have been carried out to demonstrate the performance of the system. The accurate results show that this innovative flexible FMT system has a great potential to be a powerful tool for the study of small animal disease models.
Validation of a novel microradiography device for characterization	of bone mineralization
Authors: Montagner Florian , Kaftandjian Valérie , Farlay Delphine , Brau Daniel , Boivin Georges , Follet Hélène
Published: December 2019

In order to simplify bone mineralization measurements, a system using radiographic films has been updated with a digital detector. The objective of this paper was to validate this new device. Technologies and physical phenomena involved in both systems (radiographic films and digital detector) are different. The methodology used to compare the two systems was based on image quality and assessed on two main parameters: contrast to noise ratio and spatial resolution. Results showed that the contrast to noise ratio was similar between the two systems, provided that acquisition parameters were optimized. With regard to spatial resolution, a magnification factor of at least 4 or more was required to achieve the same resolution as films. A final validation was also shown on a real image of a bone sample. The results showed that both systems have similar image quality performances, and the system using digital detector has several advantages (easier to use than films, no consumables and faster acquisition time).
Laser-Generated Plasmas: Source Requirements for X-Ray Microscopy
Authors: Michette A. G.
Published: December 2019

Microscopic imaging using x rays has been made feasible by recent developments in techniques for manufacturing x-ray optical components and in synchrotron radiation sources. However, it is clear that x-ray microscopes cannot become widely available instruments if they have to rely on synchrotron radiation sources. Laser-generated plasmas can give intense bursts of x rays, and in this paper the requirements for two types of imaging, contact microradiography and scanning transmission x-ray microscopy, are discussed, with particular reference to the use of small commercially available lasers. Such lasers could be of use, particularly for scanning x-ray microscopes, but it is unlikely they will be capable of completely replacing synchrotrons as sources for x-ray microscopy.
Design and Characterization of X-Ray Multilayer Analyzers for the 50–1000 eV Region
Authors: Henke B. L. , Gullikson E. M. , Kerner J. , Oren A. L. , Blake R. L.
Published: December 2019

This report describes a synthesis of more than 10 years of this program's development and application of multilayer analyzers for absolute Bragg spectrometry in the low-energy x-ray region of 50–1000 eV. Multilayers, denned here as systems of periodic layered structures parallel to the analyzer surface, have been applied principally in the diagnostics and application of the new, intense sources of synchrotron and high-temperature plasma x radiation. Detailed absolute reflectivity characterizations are presented for selected examples of these multilayers which have been semiempirically determined for mica, potassium acid phthalate, and the fabricated Langmuir-Blodgett and sputtered multilayer analyzers with d-spacings in the 10–200 Å range. Design requirements for absolute spectrometry are established. Efficient analytical multilayer reflectivity models are derived and parameterized (based upon a modification of the Darwin-Prins model for the low-energy x-ray region), including, for the sputtered multilayers, parameters for defining interface structure. The dependence of the reflectivity characteristics, high-order Bragg diffraction suppression, and overall efficiency upon the model parameters is analyzed. A special spectrograph and procedure for the absolute measurement of the relevant reflectivity characteristics are described. Detailed measurements and semiempirical characterizations are presented. Programs for small laboratory computers have been developed that allow rapid and flexible spectral analysis, transforming measured spectra to absolute Spectra.
Investigation of Crystal Perfection by Measuring the Collimating Slit Image Widening in Diffracted Synchrotron Radiation
Authors: Karabekov I. P. , Egikian D. L.
Published: December 2019

The development and experimental study of a method for determining the degree of surface and volume perfection of crystals by measuring the widening of the collimating slit image in synchrotron radiation beams diffracted by an (n, +n) spectrometer are presented.
Soft X-Ray Contact Microscopy of Biological Specimens: Aluminum-Coated Silicon Nitride Windows as XUV Filters
Authors: Stead A. D. , Ford T. W. , Catcheside J. A. , Hills C. P. , Ridgeley A.
Published: December 2019

The optimum wavelengths for soft x-ray contact microscopy of biological specimens are between 2.2 and 4.4 nm as, relative to water, this gives maximum contrast between carbon- and oxygen-containing constituents. Irradiation outside of this so-called “water window” interferes with either the resolution and/or the contrast that can be obtained. The previous belief that silicon nitride windows act as an effective filter for the longer wavelength, XUV radiation generated from laser-produced plasmas is shown to be suspect. However, in this study the use of aluminum-coated windows, which effectively exclude these longer wavelengths, still permits successful imaging of biological specimens. The added strength imparted to coated windows also ensures their survival during the imaging process, thereby demonstrating that the tissues can remain hydrated at the time that the image is formed in the photosensitive resist material used in this technique.
DuMond Diagram Mappings for Multi Asymmetric Crystal Monochromators
Authors: Davis Timothy J.
Published: December 2019

A set of transformation equations is derived to map DuMond diagrams between crystal faces in a multi-crystal system. The equations are constructed from the Bragg equation linearized about some angle and include the effects of refraction and asymmetry of the crystal faces. The equations form the basis of a ray tracing program for x rays to aid in the design of monochromators.
Synchrotron White Beam Topographic Imaging in Grazing Bragg-Laue Geometries
Authors: Yao G.-D. , Dudley M. , Wu J.
Published: December 2019

The technique of synchrotron white beam topographic imaging in grazing Bragg-Laue geometries has been developed at the Stony Brook synchrotron topography station (beamline X-19C) at the National Synchrotron Light Source. This technique enables both general quality characterization and imaging of defects in subsurface regions of thickness which can range from hundreds of angstroms to hundreds of micrometers as determined by the effective penetration depth of the x rays. This penetration depth, which is shown in most cases to be determined by the kinematical theory of x-ray diffraction, can be conveniently varied in a controlled manner by simple manipulation of the diffraction geometry, thereby enabling a depth profiling of the defect content. The fundamentals of the technique are described, and its advantages and disadvantages compared to existing techniques are discussed. Brief examples of the application of the technique in the characterization of defects in both single crystals and heteroepitaxial systems are given, and the general applicability of the technique is discussed.
Coherent Radiation for X-Ray Imaging—The Soft X-Ray Undulator and the X1A Beamline at the NSLS
Authors: Rarback H. , Buckley C. , Ade H. , Camilo F. , DiGennaro R. , Hellman S. , Howells M. , Iskander N. , Jacobsen C. , Kirz J. , Krinsky S. , Lindaas S. , McNulty I. , Oversluizen M. , Rothman S. , Sayre D. , Sharnoff M. , Shu D.
Published: December 2019

An undulator-based beamline was built and commissioned at the National Synchrotron Light Source to provide tunable coherent radiation in the 200–800 eV range. The low emittance of the storage ring means that the undulator source has high brightness so that a large flux of coherent x rays is delivered to experimental stations. The beamline uses a horizontally dispersing bichromator that allows two experiments to run simultaneously, making use of the first and second harmonics of the undulator output. In addition, the use of horizontally deflecting optics enables the beamline alignment to be insensitive to electron beam motion since the horizontal electron beam size is quite large. The beamline and its performance are discussed with emphasis on the optics and on stability, radiation, and vacuum considerations.
The Yoneda Effect in the Region of Ultrasoft X-Ray Radiation
Authors: Filatova E. O. , Blagoveshchenskaya T. A.
Published: December 2019

An experimental confirmation of the Yoneda effect in the region of ultrasoft x-ray radiation has been obtained. The angle-dependent scattering distributions from hexagonal BN at different glancing incidence angles and different wavelengths are described. The influence of surface treatment on anomalous scattering parameters is demonstrated. Some theoretical predictions are tested qualitatively.
Magnetic Form Factor of Nickel Determined by White Beam X-Ray Diffraction
Authors: Zukowski E. , Cooper M. J. , Armstrong R. , Ito M. , Collins S. P. , Laundy D. , Andrejczuk A.
Published: December 2019

The magnetic form factor of nickel has been measured, as a fraction of the charge form factor for {h00} and {hhh} reflections up to (10 00) and (666), by an x-ray energy dispersive white beam technique that uses elliptically polarized synchrotron radiation and single crystal samples. At low sin(θ)/λ the results are in good agreement with theory and with the values determined from neutron studies. The measurements extend beyond the current range of neutron data and indicate that significant magnetic diffraction effects are observable at sin(θ)/λ > 1.5 Å−1 if photons with energies above 26 keV can be used.
Picosecond X-Ray Pulses Generated in a Diode Driven by 193-nm Picosecond Laser Pulses
Authors: Tomov I. V. , Anderson T. , Rentzepis P. M.
Published: December 2019

A new technique for the generation of picosecond x-ray pulses is presented. Picosecond laser pulses are used to generate ultrashort electron pulses in a conventional x-ray diode in which the cathode is replaced by a photocathode. In the experiments presented, 9-ps UV pulses are employed to produce characteristic x-ray pulses with duration in range of 20-90 ps at a repetition rate of 300 Hz. This technique is inherently capable of subpicosecond x-ray pulses and synchronization of the x-ray pulses with the laser pulses or other ultrafast devices with picosecond accuracy.
Coherent Compton X-Ray Sources
Authors: Luccio A. , Miceli L.
Published: December 2019

Coherent x rays can be produced by scattering of laser light by a beam of relativistic electrons, provided that the electron beam is density modulated or the scattering is done at, or near, 90°. Since the coherent scattering is proportional to N2, where N is the number of electrons, and the incoherent scattering is proportional to N, also a modest degree of coherence can substantially increase the x-ray yield. The theory of laser-electron-beam scattering is reviewed and compared with the emission of radiation by an electron beam in an undulator. Examples of the practical implementation of an intense source of coherent x rays are discussed.
Production of Ultra Thin Silicon Foils
Authors: Medenwaldt Robin , Hettwer Manfred
Published: December 2019

Ultra thin silicon foils with thicknesses below 100 nm and large diameters have been produced. Foils with a thickness of 50–60 nm have been used as supporting foils for zone plates and as vacuum windows withstanding a pressure difference of 1 atm.
Performance Model for High Spatial Resolution Csl Scintillator Screens Coupled to CCD Detectors
Authors: Castelli Christian M. , Allinson Nigel M.
Published: December 2019

A performance model for an x-ray imaging camera that is currently being developed at York University for the recording of crystallographic diffraction patterns produced by synchrotron radiation is presented. The camera is based on charge coupled device (CCD) sensors which are coupled to a CsI(Tl) x-ray scintillator screen using 3:1 reducing fiber optic tapers. The model predicts the accuracy to which diffraction spot intensities can be measured over a range of incident x-ray flux. The effect of the point spread function of the scintillator and optics and the typical expected diffraction spot geometry is included in the model and shown to have the most significant effect on the system performance for low spot intensities, limiting the camera's effective dynamic range. However, it is shown that quantum limited performance for incident dose fluxes as low as 100 photons per spot can be readily achieved in this design. Finally, the camera performance is predicted for x-ray energies above the scintillator K absorption edges (>33 keV). The effects of energy loss through scintillation K shell fluorescent escape photons reduces the camera’s detective quantum efficiency.
Plasma X-Ray Sources Powered by Megajoule Magnetocumulative Generators
Authors: Popkov N. F. , Ya. Averchenkov V. , Pikar' A. S. , Ryaslov E. A. , Kargin V. I. , Lazarev S. A. , Borovkov V. V.
Published: December 2019

We have performed experiments using magnetocumulative generators (MCGs) to power three different types of high-energy-density plasma discharges suitable for intense x-ray generation. They include the H-pressed discharge, the capillary z-pinch, and the θ-pinch. The MCGs were operated with, and without, plasma opening switches. The characteristic currents were approximately 10 MA and characteristic time scales approximately 1 μs. In this paper we describe the characteristics of these experiments.
A 10-TW Pulsed Facility “PIRIT” for Investigation of Short-Wave Radiation Generation
Authors: Popkov N. F. , Ryaslov E. A. , Kargin V. I. , Pikar' A. S. , Kotel'nikov D. V. , Melkozerov A. V.
Published: December 2019

The results of experiments with a plasma x-ray source in the PIRIT-2000 facility are presented in this paper. The facility is designed with module capacitive energy storage energizing vacuum inductive storage. The formation of a rapidly growing current pulse as well as its commutation on a load was carried out by a plasma opening switch. A vacuum diode as well as various types of plasma loads can be used for the generation of a high-power x-ray flux. The storage energy of a 54-module capacitive storage is up to 2 MJ, its inductance is 15 nH, and its output voltage is 500 kV. The peak current in the plasma load constituted 4 MA with a 150-ns rise time. The maximum integral energy output of x radiation measured by an open thermocouple calorimeter was as high as 100 kJ, while the primary storage energy was 1 MJ. The plasma load usage at a current of 4 MA ensured a 100-kJ generation in x-ray radiation and the density of the radiation flux at a distance of 1 m from the source was as much as 0.8 J/cm2, while near the source it was 10 J/cm2.
Plasma X-Ray Radiation Source
Authors: Popkov N. F. , Kargin V. I. , Ryaslov E. A. , Pikar' A. S.
Published: December 2019

This paper gives the results of studies on a plasma x-ray source, which enables one to obtain a 2.5-krad radiation dose per pulse over an area of 100 cm2 in the quantum energy range from 20 to 500 keV. Pulse duration is 100 ns. Spectral radiation distributions from a diode under various operation conditions of a plasma are obtained. A Marx generator served as an initial energy source of 120 kJ with a discharge time of T/4 = 10−6 s. A short electromagnetic pulse (10−7 s) was shaped using plasma erosion opening switches.
Luminosity of Bragg Crystal Diffraction Spectrometers with Flat and Focusing Crystals
Authors: Lehnert U. , Zschornack G.
Published: December 2019

Analytical approximations for calculations of the luminous efficiency of Bragg crystal diffraction spectrometers with flat and focussing crystals are derived. The given approximative formulas are in good agreement with ray-tracing calculations presented in an earlier work. Influences of the geometric source dimensions on the luminous efficiency are discussed for both spectrometer types mentioned.
Pinch Plasma Source for X-Ray Microscopy with Nanosecond Exposure Time
Authors: Lebert R. , Neff W. , Rothweiler D.
Published: December 2019

The strong demand for bright, compact, and inexpensive sources for x-ray microscopy has stimulated the development of flash x-ray sources. In this paper, the requirements for such a source are analyzed under boundary conditions given by the concept of an imaging x-ray microscope using mirror condenser and Fresnel zone plates for high-resolution imaging. It is found that the Lyman-α (1s–2p) line of hydrogen-like nitrogen (N VII) at λ = 2.48 nm emitted from a nonequilibrium plasma of about 200 eV temperature and 1020 cm−3 electron density is best suited. These conditions are achieved in medium-current pinch-plasma devices. Using detailed numerical simulation of the physical processes of such a device, optimization criteria for the integrated spectral brightness (ISB) are found. Measurements of the ISB confirm these optimization criteria. The results show that the spectral emission characteristics of an optimized pinch plasma souce are compatible with the demands of the mentioned x-ray microscopy concept. These emission characteristics are compared with laser-produced plasma sources. Using the optimized source with an ISB exceeding 0.6 μJ/(μm2 sr) in a 10–20 ns pulse, wet biological samples are imaged with about 0.1 μm lateral resolution.
Non-destructive and Quantitative Investigation of Jingdezhen Blue and White Porcelains Using EDXRF
Authors: Yu K. N. , Miao J. M.
Published: December 2019

The fabrication of the calibration source is a critical part for the non-destructive and quantitative investigation of blue and white porcelains using EDXRF. In order to minimize the effects on the results due to the matrix difference between the samples and the calibration source, broken porcelain pieces of the Ming and Qing dynasties with matrix conditions similar to those of the measured samples are used directly as calibration sources. The 13 trace elements, viz. Ti, Mn, Fe, Co, Ni, Cu, Zn, Ga, Pb, Rb, Sr, Y, and Zr, have been quantitatively measured for 20 imperial blue and white porcelains of the Qing dynasty and for 11 contemporary Jingdezhen porcelains. The data are then analyzed by the principal component analysis method. The clustering of the data and the identification of the porcelains are then investigated.
X-Ray Diffraction Imaging Using Perfect Crystals
Authors: Davis T. J.
Published: December 2019

The imaging properties of perfect crystals, used for controlling and directing x-ray beams in imaging systems, are analyzed using optical transfer functions. The optical transfer functions are related to the point-spread functions for the crystal imaging system and are derived from a one-dimensional Fourier transform of the Takagi—Taupin equations. Images obtained using diffracting crystals as optical elements are simulated for the Laue and Bragg geometries using a Fourier transform method and the imaging characteristics of each of these crystal configurations are analyzed. It is demonstrated that the perfect crystals act as spatial filters of the object wave.
X-Ray Interferometry at ESRF Using Two Coherent Beams from Fresnel Mirrors
Authors: Fezzaa K. , Comin F. , Marchesini S. , Coïsson R. , Belakhovsky M.
Published: December 2019

Using two small flat mirrors under grazing incidence, we have produced interference patterns from partially coherent x-ray beams at the European Synchrotron Radiation Facility. By piezoelectrically orienting one mirror around the horizontal plane, both the vertical and horizontal transverse coherence distances of the radiation have been measured. The experimental setup can be used to characterize the coherence properties along x-ray synchrotron beamlines.
X-Ray Crystal Spectroscopy of Sub-picosecond Laser-Produced Plasmas beyond 50 keV
Authors: Hölzer G. , Förster E. , Grätz M. , Tillman C. , Svanberg S.
Published: December 2019

The interaction of a sub-picosecond (sub-ps) laser with a high-Z target produces a hard x-ray continuum, but to our knowledge no high-resolution study of the line emission is known. We present here crystal spectroscopy as a tool for the observation of energetic line x-radiation from a sub-ps laser-produced plasma. Reflection properties of flat and bent crystals for x-ray spectroscopy are analyzed theoretically for both the Bragg and the Laue geometries and optimized for a crystal spectroscopy of hard (>50 keV) x-radiation. The crystal setup is optimized for spectroscopic applications with regard to high throughput and spectral resolution. The characteristic tantalum Kα,β- and Lα,β-line emissions from a sub-ps laser-produced plasma is observed for the first time. A resolving power of about 450 is achieved which is much higher than that for comparable absorption filter techniques (E/ΔE ≈ 15).
Angular dependence of L x-ray production cross sections for Pt and	Au elements in an external magnetic field
Authors: Demir Demet , Şahin Yusuf
Published: December 2019

The effect of the external magnetic field has been investigated on the Ll, Lα, Lβ and Lγ production cross sections of Pt and Au elements in the angular range 90°–150° by using an energy dispersive x-ray fluorescence spectrometer. The samples were irradiated by using the gamma rays of 59.537 keV emitted from an $^{241}$ Am radioisotope source of 100 mCi. The external magnetic fields have been applied two opposite directions and the magnitude of the external magnetic field has been fixed at +0.75 T and −0.75 T. For B=0, Ll and Lα groups in the L x-ray lines are found to be spatially anisotropic, while those in the Lβ and Lγ peaks are isotropic. An enhancement in the differential Ll and Lα production cross sections is observed in the presence of external magnetic field. Integral cross sections for production of Ll, Lα, Lβ and Lγ x-rays were also deduced and were found to be in good agreement with the theoretical values for B=0.
Enhancement of breast calcification visualization and detection	using a modified PG method in Cone Beam Breast CT
Authors: Liu Jiangkun , Ning Ruola , Cai Weixing , Benitez Ricardo Betancourt
Published: December 2019

Cone Beam Breast CT is a promising diagnostic modality in breast imaging. Its isotropic 3D spatial resolution enhances the characterization of micro-calcifications in breasts that might not be easily distinguishable in mammography. However, due to dose level considerations, it is beneficial to further enhance the visualization of calcifications in Cone Beam Breast CT images that might be masked by noise. In this work, the Papoulis-Gerchberg method was modified and implemented in Cone Beam Breast CT images to improve the visualization and detectability of calcifications. First, the PG method was modified and applied to the projections acquired during the scanning process; its effects on the reconstructed images were analyzed by measuring the Modulation Transfer Function and the Noise Power Spectrum. Second, Cone Beam Breast CT images acquired at different dose levels were pre-processed using this technique to enhance the visualization of calcification. Finally, a computer-aided diagnostic algorithm was utilized to evaluate the efficacy of this method to improve calcification detectability. The results demonstrated that this technique can effectively improve image quality by improving the Modulation Transfer Function with a minor increase in noise level. Consequently, the visualization and detectability of calcifications were improved in Cone Beam Breast CT images. This technique was also proved to be useful in reducing the x-ray dose without degrading visualization and detectability of calcifications.
Finite detector based projection model for high spatial	resolution
Authors: Yu Hengyong , Wang Ge
Published: December 2019

For finite detector and focal spot sizes, here we propose a projection model for high spatial resolution. First, for a given x-ray source point, a projection datum is modeled as an area integral over a narrow fan-beam connecting the detector elemental borders and the x-ray source point. Then, the final projection value is expressed as the integral obtained in the first step over the whole focal spot support. An ordered-subset simultaneous algebraic reconstruction technique (OS-SART) is developed using the proposed projection model. In the numerical simulation, our method produces improved spatial resolution and suppresses high-frequency artifacts.
In vivo photoacoustic imaging of model of port wine stains
Authors: Yuan Kaihua , Yuan Yi , Gu Ying , Gao Jianhua , Xing Da
Published: December 2019

Port wine stains are categorized as a benign capillary vascular malformation, which is hard to cure. In this paper, a photoacoustic microscopy system, which integrated a two-dimensional scanning galvanometer, an objective lens and a focused ultrasound transducer, was designed for noninvasive imaging of blood vessels of port wine stains model in vivo. Cock comb was chosen as the port wine stains model in the experiment. The blood vessels in x-y plane and x-z plane were imaged clearly. Experimental results demonstrate that photoacoustic microscopy can image the blood vessels of port wine stains model in vivo with high contrast and high resolution. It has the potential for clinical applications in detecting the blood vessels in port wine stains skin.
Kapital gegen Leben
Authors: Streichhahn Vincent , Kipka Ronda
Published: December 2019

Im Anschluss an Lise Vogel konzentriert sich dieser Artikel auf eine werttheoretische Diskussion des Reproduktionsbegriffs. Die Autor_innen wollen damit in die aktuellen Debatten über die soziale Reproduktion eingreifen. Der werttheoretische Ansatz basiert auf einer feministischen Kritik der politischen Ökonomie und betont die Notwendigkeit der Reproduktion der Ware Arbeitskraft für den kapitalistischen Reproduktionsprozess. Die systematischeVerflechtung von Produktion und Reproduktion kann dadurch theoretisch systematischer erfasst werden als mit bisherigen Ansätzen. Ein zentraler Befund zeigt, dass die Ausbeutungsrate auch durch historisch spezifische Reproduktionsstrategien reguliert wird. Klassenkämpfe finden daher mitnichten nur in der Fabrik, sondern auch im öffentlichen Reproduktionssektor, wie dem Bildungs- und Gesundheitswesen statt.
Herrschaftskritik und radikale Demokratie
Authors: Georgi Fabian , Mayer Margit , Roth Roland , Wissen Markus , Vogelskamp Dirk
Published: December 2019

Nachruf auf Wolf-Dieter Narr.