X-ray Talbot-Lau Interferometer Research Articles

Detection of early pulmonary emphysema by multi-contrast x-ray Talbot-Lau interferometer.

Pulmonary emphysema is a part of chronic obstructive pulmonary disease, which is an irreversible chronic respiratory disease. In order to avoid further damage to lung tissue, early diagnosis and treatment of pulmonary emphysema is essential. Early pulmonary emphysema diagnosis is difficult with conventional radiographic imaging. Recently, x-ray phase contrast imaging has proved to be an effective and promising imaging strategy for soft tissue, due to its high sensitivity and multi-contrast. The aim of this study is to diagnose pulmonary emphysema early utilizing an x-ray Talbot-Lau interferometer (TLI). We successfully established the mouse model of emphysema by porcine pancreatic elastase treatment, and then used the established x-ray TLI to perform imaging experiments on the mice with different treatment time. The traditional absorption CT and phase contrast CT were obtained simultaneously through TLI. The CT results and histopathology of mice lung in different treatment time were quantitatively analyzed. By imaging mice lungs, it can be found that phase contrast has higher sensitivity than absorption contrast in early pulmonary emphysema. The results show that the phase contrast signal could distinguish the pulmonary emphysema earlier than the conventional attenuation signal, which can be consistent with histological images. Through the quantitative analysis of pathological section and phase contrast CT, it can be found that there is a strong linear correlation. In this study, we quantitatively analyze mean linear intercept of histological sections and CT values of mice. The results show that the phase contrast signal has higher imaging sensitivity than the attenuation signal. X-ray TLI multi-contrast imaging is proved as a potential diagnostic method for early pulmonary emphysema in mice.

Impact of Void in CFRP on Dark-field Images Derived via X-ray Talbot-Lau Interferometer

Impact of Void in CFRP on Dark-field Images Derived via X-ray Talbot-Lau Interferometer

High energy x-ray Talbot-Lau interferometer employing a microarray anode-structured target source to extend the field of view.

High energy and large field of view (FOV) phase contrast imaging is crucial for biological and even medical applications. Although some works have devoted to achiving a large field of view at high energy through bending gratings and so on, which would be extremely challenging in medical high energy imaging. We analyze the angular shadowing effect of planar gratings in high-energy X-ray Talbot-Lau interferometer (XTLI). Then we design and develop an inverse XTLI coupled with a microarray anode-structured target source, to extend the FOV at high energy. Our experimental results demonstrate the benefit of the source in inverse XTLI and a large FOV of 106.6 mm in the horizontal direction is achieved at 40 keV. Based on this system, experiments of a mouse demonstrate the potential advantage of phase contrast mode in imaging lung tissue. We extend the FOV in a compact XTLI using a microarray anode-structured target source coupled with an inverse geometry, which eliminates grating G0 and relaxes the fabrication difficulty of G2. We believe the established design idea and imaging system would facilitate the wide applications of XTLI in high energy phase contrast imaging.

X-ray grating interferometry design for the 4D GRAPH-X system

The 4D GRAPH-X (Dynamic GRAting-based PHase contrast x-ray imaging) project aims at developing a prototype of an x-ray grating-based phase-contrast imaging scanner in a laboratory setting, which is based on the Moirè single-shot acquisition method in order to be optimized for analysing moving objects (in the specific case, a dynamic thorax phantom), that could evolve into a suitable tool for biomedical applications although it can be extended to other application fields. When designing an x-ray Talbot-Lau interferometer, high visibility and sensitivity are two important figures of merit, strictly related to the performance of the system in obtaining high quality phase contrast and dark-field images. Wave field simulations are performed to optimize the setup specifications and construct a high-resolution and high-sensitivity imaging system. In this work, the design of a dynamic imaging setup using a conventional milli-focus x-ray source is presented. Optimization by wave front simulations leads to a symmetric configuration with 5.25 μm pitch at third Talbot order and 45 keV design energy. The simulated visibility is about 22%. Results from GATE based Monte Carlo simulations show a 19% transmission percentage of the incoming beam into the detector after passing through all the gratings and the sample. Such results are promising in view of building a system optimized for dynamic imaging.

Relation between dark-field images derived using X-Ray Talbot–Lau interferometer and carbon fiber distribution in CFRP

This study proposes a model that relates the carbon fiber arrangement and orientation in CFRP to the dark-field images captured by X-ray Talbot-Lau interferometer (TLI). X-ray TLI visualizes X-ray phase contrast, which is more sensitive to light elements such as carbon, than conventional X-ray absorption contrast. By using TLI, novel non-destructive inspection (NDI) technique for CFRP reinforced by distributed discontinuous carbon fibers, which precisely evaluates local orientation and distribution of fibers in large area, can be developed. The model proposed in this study forms the basis of such NDI technique. In this paper, the model is proposed first, and material parameters needed for the model are then identified from the TLI dark-field images of the multi-fiber composite (MFC) specimens. The proposed model is validated by comparing the dark-field images simulated by the model to those experimentally measured by TLI.

Relationship between Dark-field Images Derived by X-Ray Talbot-Lau Interferometer and Carbon Fiber Distribution in CFRP

Relationship between Dark-field Images Derived by X-Ray Talbot-Lau Interferometer and Carbon Fiber Distribution in CFRP

Model-driven phase retrieval network for single-shot x-ray Talbot-Lau interferometer imaging.

The single-shot x-ray Talbot-Lau interferometer-based differential phase contrast (DPC) imaging is able to accelerate time-consuming data acquisition; however, the extracted phase image suffers from severe image artifacts. Here, we propose to estimate the DPC image via a deep convolutional neural network (CNN) incorporated with the physical imaging model. Instead of training the CNN with thousands of labeled data beforehand, both phantom and biological specimen validation experiments show that high-quality DPC images can be automatically generated from only one single-shot projection image with a certain periodic moiré pattern. This work provides a new, to the best of our knowledge, paradigm for single-shot x-ray DPC imaging.

Phase Contrast CT Enabled Three-Material Decomposition in Spectral CT Imaging.

Three-material decomposition is crucial for material quantification when more than two elemental materials, including a K-edge material, are presented in an image object. In principle, three-material decomposition requires a triple energy scan which cannot be directly accomplished using a conventional dual energy CT system. In this work, a new scheme to enable three-material decomposition by employing phase contrast CT was presented. When a grating interferometer is added, a conventional absorption dual energy CT system can be upgraded to a phase contrast dual energy CT system which provides an additional phase signal related to the real part of the refractive index of an image object, along with the absorption signal under two different x-ray spectra. In this work, a three-material decomposition method was proposed for the aforementioned dual energy phase contrast CT system. Physical experimental studies were performed on a benchtop x-ray Talbot-Lau interferometer system to validate the proposed method. A physical phantom, containing calcium and iodine inserts of known concentrations, was used as the image object. A rotation-rotation dual energy phase contrast CT scan was performed under 40 and 80 kVp tube potentials. For each view angle, a phase stepping procedure with five phase steps was performed. After the phase retrieval procedure and image reconstruction using the standard filtered-back projection, the solutions were decomposed into the calcium, iodine and water bases based on the proposed decomposition method. For all the solutions, the relative quantification errors of the concentrations were within 10%.

Preliminary demonstration of flexible dual-energy x-ray phase-contrast imaging

Currently, dual-energy X-ray phase contrast imaging is usually conducted with an X-ray Talbot-Lau interferometer. However, in this system, the two adopted energy spectra have to be chosen carefully in order to match well with the phase grating. For example, the accelerating voltages of the X-ray tube are supposed to be respectively set as 40 kV and 70 kV, with other energy spectra being practically unusable for dual energy imaging. This system thus has low flexibility and maneuverability in practical applications. In this work, dual energy X-ray phase-contrast imaging is performed in a grating-based non-interferometric imaging system rather than in a Talbot-Lau interferometer. The advantage of this system is that, theoretically speaking, any two separated energy spectra can be utilized to perform dual energy X-ray phase-contrast imaging. The preliminary experimental results show that dual-energy X-ray phase contrast imaging is successfully performed when the accelerating voltages of the X-ray tube are successively set as 40 kV and 50 kV. Our work increases the flexibility and maneuverability when employing dual-energy X-ray phase-contrast imaging in medical diagnoses and nondestructive tests.

X-ray phase-imaging scanner with tiled bent gratings for large-field-of-view nondestructive testing

X-ray phase imaging based on X-ray Talbot-Lau interferometry is an emerging nondestructive testing (NDT) method applicable to materials consisting of light elements such as organic and plastic materials. Aiming at future application to the examination of objects carried on conveyor systems, a scanner-type X-ray phase imaging apparatus is developed. Following the verification of the algorithm for phase-scanner image formation (S. Bachche et al., Sci. Rep., 2017), we report on a development with a desk-sized compact configuration and a 200-mm-wide field of view. Gratings used to construct an X-ray Talbot-Lau interferometer are bent and tiled. A scan speed of 9.2 mm/s with a spatial resolution of 0.29 mm is achieved in resultant images of absorption and scattering. Three scattering images are obtained for a carbon fiber reinforced plastic sample by changing its orientation against the gratings to visualize anisotropic fibrous structures.

X-Ray Phase Contrast Imaging by Talbot-Lau Interferometer Without Phase-Stepping Device

A new X-ray phase-contrast imaging on Talbot-Lau interferometer without phase-stepping device is proposed. A new analyzer grating is designed to replace the existing analyzer grating and scintillation conversion screen in the X-ray imaging system which is interlaced by the low-energy grid bars and the high-energy grid bars. Employing the new analyzer grating, the X-ray Talbot-Lau interferometer can obtain the differential phase-contrast image without the phase-stepping device by changing X-ray exposure energy only once. The simplified imaging system results in higher imaging efficiency and lower radiation dose. The experimental result shows that the imaging system can obtain a differential phase-contrast image of the specimen.

Cascade Talbot–Lau interferometers for x-ray differential phase-contrast imaging

X-ray Talbot–Lau interferometer (TLI)-based differential phase-contrast imaging (DPCI), owing to its potential capability of multiple contrast mechanisms and adaptability for variety of samples, has attracted wide spread attention in the last decade. However, the fabrication of the absorption grating, an indispensable element in a conventional TLI, presents a significant challenge for practical applications. Here, we report on a cascaded TLI (CTLI) configuration for DPCI, i.e. a TLI followed by an inverse TLI (ITLI), through which the small-period high-aspect-ratio (HAR) absorption gratings (analyzer gratings and source gratings in the conventional TLI and ITLI, respectively) could be omitted. Instead, the large-period absorption gratings (generally tens of microns) are allowed to be employed, which significantly relieves the grating fabrication difficulties, especially for the large-area ones. The success of our CTLI configuration is validated by the observation of moiré fringes, and the resulting phase-contrast and visibility-contrast images for DPCI. Moreover, our CTLI configuration is promising to yield magnified interference fringes capable of being detected directly by commonly used large-area detectors.

Laboratory-based X-ray phase-imaging scanner using Talbot-Lau interferometer for non-destructive testing

An X-ray Talbot-Lau interferometer scanning setup consisting of three transmission gratings, a laboratory-based X-ray source that emits X-rays vertically, and an image detector on the top has been developed for the application of X-ray phase imaging to moving objects that cannot be tested clearly with conventional absorption contrast. The grating-based X-ray phase imaging method usually employs a phase-stepping (or fringe-scanning) technique by displacing one of the gratings step-by-step while the object stays still. Since this approach is not compatible with a scanner-type application for moving objects, we have developed a new algorithm for achieving the function of phase-stepping without grating displacement. By analyzing the movie of the moiré pattern as the object moves across the field of view, we obtain the absorption, differential phase, and visibility images. The feasibility of the X-ray phase imaging scanner has been successfully demonstrated for a long sample moving at 5 mm/s. This achievement is a breakthrough for the practical industrial application of X-ray phase imaging for screening objects carried on belt-conveyers such as those in factories.

Non-destructive study of fruits using grating-based X-ray imaging

Grating-based X-ray imaging can make use of conventional tube sources to provide absorption, refraction and scattering contrast images from a single set of projection images efficiently. In this paper, a fresh cherry tomato and a dried umeboshi are imaged by using X-ray Talbot–Lau interferometer. The seed distribution in the scattering image of the cherry tomato, and the wrinkles of epicarp in the refraction image of the umeboshi, are shown distinctly. The refraction and scattering images provide more information on subtle features than the absorption image. Also, the contrast-to-noise ratio values show distinguishing capacity of the three kinds of imaging techniques. The results confirm that grating-based X-ray imaging is of great potential in non-destructive fruit testing.

Experimental research on the feature of an x-ray Talbot–Lau interferometer versus tube accelerating voltage**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), the National Natural Science Foundation of China (Grant Nos. 11179004, 10979055, 11205189, and 11205157), and the Japan–Asia Youth Exchange Program in

X-ray Talbot–Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a conventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus bearing tremendous potential for future clinical diagnosis. In this work, by changing the accelerating 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. Experimental 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.

Energy-dependent visibility measurements, their simulation and optimisation of an X-ray Talbot-Lau Interferometer

The visibility is a crucial quality parameter in grating-based X-ray phase-contrast imaging as it directly influences the noise of the obtained phase signal. In order to evaluate its behaviour with respect to energy, we used the photon counting semiconductor detector Timepix to obtain a series of measurements at different energy thresholds. These energy-dependent measurements of the visibility response of a Talbot-Lau Interferometer for X-ray phase-contrast imaging are presented in this paper. Furthermore, we report on the results of our effort to model this behaviour in our simulation, where a very good agreement between measurement and simulation could be achieved for two available setups. With this tested workflow we are now able to predict the expected visibility response of a specific setup.This capability is an important prerequisite for the optimisation of an X-ray Talbot-Lau Interferometer. It is predicted that the visibility of our current laboratory setup could be doubled by choosing an appropriate X-ray spectrum or filter material.

Quantitative coherence analysis with an X-ray Talbot–Lau interferometer

Differential phase-contrast (DPC) X-ray imaging has been performed in the Talbot-Lau configuration, in which the X-ray source was a combination of an absorption grating and a laboratory X-ray generator. We report here quantitative analysis of partial coherence effects on the X-ray Talbot-Lau interferometer. Based on the visibility of the self-image, the well-known geometry condition is reproduced. It is shown that effects of partial coherence are determined by the opening ratio of the source grating, and that the effects are independent of the Talbot order and the type of the phase grating, a condition quite different from those in a Talbot interferometer. A possible explanation is discussed from the point of view of the effective spatial coherence length. Taking into account the available X-ray flux and experimental fluctuations, we present the optimum opening ratio. Furthermore, we mention that our results can also be successfully used to discuss the properties of a multiline X-ray source.

Fabrication of Multiple Slit Using Stacked-Sliced Method for Hard X-ray Talbot–Lau Interferometer

We propose using a multiple slit fabricated by a simple and economical stacked-sliced method for X-ray phase imaging with a Talbot–Lau X-ray interferometer. Foils of Ta and Al were stacked alternately, and the stack was sliced up perpendicular to the stacking direction. We successfully fabricated a hard X-ray multiple slit with a space size (Al foil thickness) of about 10 µm and an aspect ratio of 60. Optical microscopy evaluation showed its regular pitch pattern at its surface. A high-resolution X-ray transmission image proved the regularity of the inner part. The visibility of moiré fringes and the phase-contrast image obtained using the Talbot–Lau interferometer with the multiple slit proved the feasibility of the stacked-sliced approach.