Super-Resolution Scanning Transmission X-Ray Imaging Using Single Biconcave Parabolic Refractive Lens Array.

A new super resolution imaging technique which potentially enables sub-µm spatial resolution, using a detector of pixels much larger than the spatial resolution, is proposed. The method utilizes sample scanning through a large number of identical X-ray microprobes periodically spaced (the period corresponds to a multiple of the pixel size), which reduces drastically the scanning time. The information about the sample illuminated by the microprobes is stored by large detector pixels. Using these data and sample position information, a super-resolution image reconstruction is performed. With a one-dimensional (1D) high aspect ratio nickel single lens array designed for theoretically expected sub-µm microprobes at 17 keV and fabricated by deep X-ray lithography and electroforming technique, 2 µm X-ray microprobes with a period of 10 µm were achieved. We performed a first experiment at KARA synchrotron facility, and it was demonstrated that the smallest structure of a test pattern with a size of 1.5 µm could be easily resolved by using images generated from a detector having a pixel size of 10.4 µm. This new approach has a great potential for providing a new microscopic imaging modality with a large field of view and short scan time.

An improved phase shift reconstruction algorithm of fringe scanning technique for X-ray microscopy.

The X-ray phase imaging method has been applied to observe soft biological tissues, and it is possible to image the soft tissues by using the benefit of the so-called "Talbot effect" by an X-ray grating. One type of the X-ray phase imaging method was reported by combining an X-ray imaging microscope equipped by a Fresnel zone plate with a phase grating. Using the fringe scanning technique, a high-precision phase shift image could be obtained by displacing the grating step by step and measuring dozens of sample images. The number of the images was selected to reduce the error caused by the non-sinusoidal component of the Talbot self-image at the imaging plane. A larger number suppressed the error more but increased radiation exposure and required higher mechanical stability of equipment. In this paper, we analyze the approximation error of fringe scanning technique for the X-ray microscopy which uses just one grating and proposes an improved algorithm. We compute the approximation error by iteration and substitute that into the process of reconstruction of phase shift. This procedure will suppress the error even with few sample images. The results of simulation experiments show that the precision of phase shift image reconstructed by the proposed algorithm with 4 sample images is almost the same as that reconstructed by the conventional algorithm with 40 sample images. We also have succeeded in the experiment with real data.

X-ray Bragg magnifier microscope as a linear shift invariant imaging system: image formation and phase retrieval.

We present the theoretical description of the image formation with the in-line germanium Bragg Magnifier Microscope (BMM) and the first successful phase retrieval of X-ray holograms recorded with this imaging system. The conditions under which the BMM acts as a linear shift invariant system are theoretically explained and supported by the experiment. Such an approach simplifies the mathematical treatment of the image formation and reconstruction as complicated propagation of the wavefront onto inclined planes can be avoided. Quantitative phase retrieval is demonstrated using a test sample and a proof of concept phase imaging of a spider leg is also presented.

On the origin of visibility contrast in x-ray Talbot interferometry.

The reduction in visibility in x-ray grating interferometry based on the Talbot effect is formulated by the autocorrelation function of spatial fluctuations of a wavefront due to unresolved micron-size structures in samples. The experimental results for microspheres and melamine sponge were successfully explained by this formula with three parameters characterizing the wavefront fluctuations: variance, correlation length, and the Hurst exponent. The ultra-small-angle x-ray scattering of these samples was measured, and the scattering profiles were consistent with the formulation. Furthermore, we discuss the relation between the three parameters and the features of the micron-sized structures. The visibility-reduction contrast observed by x-ray grating interferometry can thus be understood in relation to the structural parameters of the microstructures.

Hard-X-ray phase-difference microscopy using a fresnel zone plate and a transmission grating.

Novel hard x-ray phase imaging microscopy that simply uses an objective and a transmission grating is described. The microscope generated an image that exhibited twin features of a sample with an opposite phase contrast having a separation of a specific distance. Furthermore, the twin features were processed to generate an image mapping the x-ray phase shift through a simple algorithm. The presence of the grating did not degrade the spatial resolution of the microscope. The sensitivity of our microscope to light elements was about 2 orders of magnitude higher than that of the absorption contrast microscope that was attained by simply removing the grating. Our method is attractive for easily appending a quantitative phase-sensitive mode to normal x-ray microscopies, and it has potentially broad applications in biology and material sciences.

Blood vessels: depiction at phase-contrast X-ray imaging without contrast agents in the mouse and rat-feasibility study.

The ability of phase-contrast x-ray imaging to depict blood vessels without contrast agents was tested by observing livers of a mouse and a rat with synchrotron x rays. Livers were excised by tying arteries and veins to prevent blood from flowing out of the liver. An x-ray interferometer was used to obtain x-ray phase contrast. With the technique of phase-shifting x-ray interferometry, the image mapping x-ray phase shift caused by a liver was measured. The x-ray phase shift caused by blood was substantially different from that caused by other soft tissues; consequently, trees of blood vessels were revealed on the image. Vessels with diameter smaller than 0.1 mm were recognized. This result allows new possibilities for investigation of the vascular system.

Psychological effects of aromatherapy on chronic hemodialysis patients.

Effects of aromatherapy (odorless condition, lavender, and hiba oil) on mood and anxiety were investigated in 14 female patients who were being treated with chronic hemodialysis. A control period consisting of natural hospital smells was established before each test session, and then aromatic test conditions were systematically evaluated for odorless conditions as well as aromatic conditions containing lavender and hiba oil aromas. The effects of aromatherapy were measured using the Hamilton rating scale for depression (HAMD) and the Hamilton rating scale for anxiety (HAMA). Hiba oil aroma significantly decreased the mean scores of HAMD and HAMA, and lavender aroma significantly decreased the mean scores of HAMA. The mean scores of HAMD and HAMA in an odorless condition were not significantly different from those of the control conditions. These results indicate that in chronic hemodialysis patients hiba oil is an effective, non-invasive means for the treatment of depression and anxiety, and that lavender alleviates anxiety.

New types of X-ray computed tomography (CT) with synchrotron radiation: fluorescent X-ray CT and phase-contrast X-ray CT using interferometer.

New types of X-ray computed tomography (CT), fluorescent X-ray CT and phase-contrast X-ray CT are being developed for biomedical research. While fluorescent scanning X-ray CT (FXCT) can detect specific contrast elements, or endogenous iodine, at very low content (less than 400 pg iodine of tissue in a volume of 8 x 10(-6) ml), the phase-contrast X-ray CT (PCCT) is a highly sensitive imaging technique to differentiate between different biological tissue types (based on their specific gravity variation) without the use of a contrast agent. Therefore, we can expect functional diagnosis with FXCT, and high contrast, high resolution biological imaging with PCCT. In this paper, a human thyroid gland imaged by FXCT, and a metastatic human cancerous lesion depicted using PCCT are presented. The latter method used a newly manufactured, large, monolithic, X-ray interferometer, which is described in this paper in detail.

Human carcinoma: early experience with phase-contrast X-ray CT with synchrotron radiation--comparative specimen study with optical microscopy.

Phase-contrast x-ray computed tomography (CT) indicates the distribution of the refractive index and has potential to reveal the structures inside soft tissues without a contrast agent. With a synchrotron x-ray source, phase-contrast x-ray CT with a triple Laue-case x-ray interferometer clearly differentiated various human pathologic tissues in the cases of hepatocellular carcinoma with cirrhosis and metastatic colon carcinoma to the liver, and the images closely corresponded to those obtained with low-magnification optical microscopy.

Phase-contrast X-ray imaging with a large monolithic X-ray interferometer.

To increase the field of view for large objects in phase-contrast X-ray imaging, a large monolithic X-ray interferometer has been fabricated using an available silicon ingot of diameter 10 cm. A performance study of this interferometer has been carried out using a synchrotron X-ray source. The view size of the interference pattern obtained with this interferometer was 25 mm wide and 15 mm high and its visibility was 79%. Various structures of a sliced human hepatocellular carcinoma were identified as necrosis, hemorrhagic necrosis, normal liver tissue and blood vessel. The performance of this interferometer was sufficient for phase-contrast X-ray imaging.

Effect of pressure distribution of shockwave on renal hemorrhage after extracorporeal shockwave lithotripsy: comparison of EDAP LT-01 and Siemens Lithostar.

BACKGROUND: Renal hemorrhage is the most common adverse effect of SWL, and it has been speculated to be related to the type of lithotripter used. METHODS: We investigated the incidence of renal hemorrhage in patients with urinary stones who underwent lithotripsy using either the EDAP LT-01 or the Siemens Lithostar. In addition, we performed in vitro experiments using pressure-sensitive paper in conjunction with gelatin, agar, or porcine tissue models of renal lithotripsy. RESULTS: Thirty-one (16.6%) of 187 kidneys treated with the EDAP LT-01 and 44 (19.6%) of 225 kidneys treated with the Siemens Lithostar showed intrarenal or subcapsular hemorrhage or perinephric hematoma. In particular, the incidence of subcapsular hematoma was significantly higher in the Lithostar-treated patients (P < 0.0001). We discuss our results in light of the patterns of pressure distribution obtained from the two lithotripter units using in vitro models with colorometric, pressure-sensitive paper. CONCLUSION: It appears that the Siemens Lithostar exerts a greater pressure on the renal capsule, which may account for the higher incidence of subcapsular hematoma.

[Histopathological observations on bullous keratopathy after argon-laser iridotomy].

PURPOSE: To elucidate histopathological mechanism of bullous keratopathy after argon-laser iridotomy (ALI). CASE AND METHOD: The patient was a 60-year-old female who underwent penetrating keratoplasty because of bullous keratopathy after 2 years and 2 months of ALI. The corneal specimen was fixed with a mixture of 2.5% formalin and 1.0% glutaraldehyde, and examined under light and electron microscopes. FINDING AND CONCLUSION: Laser-damaged endothelium produced a large amount of basement membrane-like material beneath Descemet's membrane. At the next stage, the severely damaged endothelium lost its organellae and cell membranes, and fell off. The surrounding healthy endothelium migrated into the damaged area and produced a small amount of material like basement membrane which covered Descemet's membrane. After that, stromal swelling, decrease of keratocytes, breaking and disappearance of Bowman's membrane, epithelial edema, connective tissue accumulation beneath basal cells, and epithelial detachment occurred in the laser-damaged area.

Remission of Ménétrier's disease after a prolonged period with therapeutic eradication of Helicobacter pylori.

We report here a case of Ménétrier's disease (MD) that required a prolonged period for remission after eradication therapy of Helicobacter pylori (HP). The appropriate time needed to judge the efficacy of the eradication therapy for HP infection in an MD case is discussed.

Phase-Contrast Tomographic Imaging Using an X-ray Interferometer.

Apparatus for phase-contrast X-ray computed tomography using a monolithic X-ray interferometer is presented with some observational results for human breast tissues. Structures characteristic of the tissues were revealed in the phase-contrast tomograms. The procedure of image analysis consists of phase retrieval from X-ray interference patterns and tomographic image reconstruction from the retrieved phase shift. Next, feasibility of phase-contrast imaging using a two-crystal X-ray interferometer was studied aiming at in vivo observation in the future. In a preliminary study, the two-crystal X-ray interferometer was capable of generating fringes of 70% visibility using synchrotron X-rays.

Characterization of windows and filters for coherent X-ray beamlines.

Beryllium windows and graphite heat absorbers used in coherent X-ray beamlines must be optically flat. If the optical path through the window varies by more than lambda/4, the X-ray wave front will be distorted after passing through the window, and the divergence of the X-ray beam may be increased. This reduces the beam coherence. Beryllium, graphite and Kapton films have been tested using ultra-small-angle X-ray scattering. Wave-front distortion was also directly observed by means of phase-contrast X-ray microradiography. The measured increase of angular divergence is about 4 micro rad. The wave-front distortion is larger than 2pi (optical path difference of lambda). These are serious problems for utilizing coherent X-ray beams.

Investigation of the phase shift in X-ray forward diffraction using an X-ray interferometer.

The phase shift of forward-diffracted X-rays by a perfect crystal is discussed on the basis of the dynamical theory of X-ray diffraction. By means of a triple Laue-case X-ray interferometer, the phase shift of forward-diffracted X-rays by a silicon crystal in the Bragg geometry was investigated.

Phase-contrast X-ray CT image of breast tumor.

Phase-contrast X-ray CT images generated by differences in refractive indices can be used to visualize the internal structures of soft tissues without contrast enhancement. In this study, imaging of human breast tumor was performed on formalin-fixed samples. Experiments were carried out at the synchrotron source of the Photon Factory, Tsukuba, Japan. The X-ray energy was adjusted to 17.7 keV. Phase-contrast X-ray CT images revealed various structures of human breast tumor as clearly as optical images.

[Doping test for racehorses in Japan].

The doping test method used in a horse race requires the accurate detection of a wide variety of drugs and metabolites as well as the rapidity in order to examine a large number of samples within a limited time. For this purpose, the routine method consists of a preliminary screening and a confirmatory test. In this paper, a historical review for the development of the doping test method in Japan is described. The metabolism and pharmacology of drugs in horses are also discussed.

Operation of a Two-Crystal X-ray Interferometer at the Photon Factory.

A two-crystal X-ray interferometer for phase-contrast X-ray imaging is reported. Mechanical stability of less than 0.1 nm is required to operate the two-crystal interferometer. The feasibility of using such an interferometer at the Photon Factory using synchrotron radiation has been investigated. Interference fringes of 70% visibility were observed with 0.092 nm X-rays. This result indicates that the two-crystal X-ray interferometer can be applied to phase-contrast X-ray imaging.