Simulation based evaluation of a fan beam coded aperture x-ray diffraction imaging system for biospecimen analysis

X-ray transmission imaging has been used in a variety of applications for high-resolution measurements based on shape and density. Similarly, X-ray diffraction (XRD) imaging has been used widely for molecular structure-based identification of materials. Combining these X-ray methods has the potential to provide high-resolution material identification, exceeding the capabilities of either modality alone. However, XRD imaging methods have been limited in application by their long measurement times and poor spatial resolution, which has generally precluded combined, rapid measurements of X-ray transmission and diffraction. In this work, we present a novel X-ray fan beam coded aperture transmission and diffraction imaging system, developed using commercially available components, for rapid and accurate non-destructive imaging of industrial and biomedical specimens. The imaging system uses a 160 kV Bremsstrahlung X-ray source while achieving a spatial resolution of ≈ 1 × 1 mm2 and a spectral accuracy of > 95% with only 15 s exposures per 150 mm fan beam slice. Applications of this technology are reported in geological imaging, pharmaceutical inspection, and medical diagnosis. The performance of the imaging system indicates improved material differentiation relative to transmission imaging alone at scan times suitable for a variety of industrial and biomedical applications.

X-ray diffraction imaging (XDI) is a novel modality in which the local x-ray diffraction (XRD) properties of inhomogenous objects are measured. Following a brief description of some of the areas in which x-ray diffraction is currently impacting on the detection of materials of interest in the security environment, the principles of energy-dispersive x-ray diffraction tomography employed in XDI are described. The Multi-Inverse Fan Beam (MIFB) topology for 3rd Generation XDI, in which the XRD properties of a spatial array of 2-D volume elements are investigated in parallel without mechanical scanning, is described. 3rd Generation XDI is being driven among other things by rapid technological developments taking place in the field of spectroscopic, room-temperature, semiconductor x-ray detectors. Detector requirements for Next-Generation MIFB XDI are summarized and the potential of 3rd Generation XDI for rapid, accurate and affordable screening in the Checkpoint and Hold Baggage environments is summarized.

To evaluate the lattice misorientation at domain boundaries (DBs) in β‐Ga2O3, we performed X‐ray diffraction imaging (XRDI), X‐ray reticulography (XRR), and X‐ray topography (XRT) using a synchrotron radiation light source. Four reciprocal lattice vectors (g‐vectors) were applied, and the DBs showed different visibilities in the XRDI maps depending on the g‐vector. By analyzing possible characteristics of the misorientation, the XRDI results suggested that the DB being investigated was associated with a misorientation on the () plane and contained twist and tilt components. The apparent peak change in XRDI caused by the two components was calculated. We further succeeded in separating the tilt and twist components using XRR images in conjunction with simulation. Dislocation arrays at the DBs were observed using XRT, and the average distance between the dislocations in the array was consistent with the misorientation obtained using XRDI and XRR. The distribution of DBs across a wide area was acquired by a combination of XRR images recorded on a charge‐coupled device camera and X‐ray films. The fringe‐patterned XRR on X‐ray films provided a powerful and nondestructive tool to characterize DBs distributed across a large‐diameter wafer with an angular resolution on the order of several arc sec (low 10−5 rad).

The size of hydroxyapatite (HAP) crystals in calcified cartilage and cortical bone of the rat has been studied and compared with that of synthetic poorly crystalline hydroxyapatite (PCHA). Crystal size was determined by X-ray diffraction and selected-area dark field imaging, and their elemental compositions were determined by emission spectroscopy. The crystal size of cartilage, bone, and PCHA were found to be between 120 and 170 A in length by 50 A in width as determined by both X-ray diffraction and dark field imaging. Cartilage had a lower ash weight than bone but both have the same Ca/P ratio of 1.6. These findings, though in agreement with the X-ray diffraction literature, differ from observations made by conventional bright field electron microscopy. We conclude that mineral sites in cartilage and bone, which exist as platelike structures, are in fact aggregates of small 120-170 X 50 A HAP crystals. The consequences of these findings was discussed in view of crystal relationships with collagen and other macromolecules.

A detectable difference in X-ray diffraction data of healthy and diseased breast tissues has been observed. This information can be used to generate images with a higher contrast than that of conventional transmission mammography. A diffraction enhanced breast imaging (DEBI) system that simultaneously combines transmission and diffraction breast images is currently being developed. This paper presents the imaging system requirements for a clinical DEBI system. The DEBI imaging system employs a phosphor coated L3Vision CCD camera. The DEBI principle has been assessed at the SYRMEP synchrotron beamline (Elettra, Trieste) and with a purpose built mammographic X-ray imaging unit. Diffraction enhanced images have been obtained of realistic breast tissue phantoms, consisting of 4 cm thick slabs of excised breast tissue containing embedded carcinomas. The images were obtained at pre-determined momentum transfer values, allowing some tissue characterization to be achieved during imaging, as well as optimizing image contrast This paper presents the current state of the project. The spatial resolution of the diffraction images have been studied using test phantoms and suggestions are made for the collimation systems necessary for a clinical system. A correction procedure applied to the diffraction images is also presented.

X-ray diffraction tomography (XDT) probes the spatially variant x-ray diffraction (XRD) profile within volumetric objects. Here, we demonstrate a tabletop XDT setup with coded cone-beam illumination that accelerates the acquisition process of three-dimensional (3D) objects. Compared to the attenuation-based x-ray computed tomography (CT), XDT images display high contrast and specificity among materials with similar absorption coefficients. However, due to the weak signal level of diffraction and the low efficiency in source utilization and detection, conventional XDT systems require high-brilliance synchrotron sources to manage the acquisition time. In this paper, we propose a coded-illumination XDT system that utilizes the cone-beam from a tabletop x-ray tube and eliminates the detector-side collimation. The multiplexed measurement promotes parallelization in the data acquisition and enables simple implementation of compressive measurements, addressing the need of tabletop XDT systems in industrial nondestructive testing and medical imaging applications. We have demonstrated 1 order of magnitude reduction in XDT acquisition time, making high-contrast 3D x-ray imaging accessible to various research and application areas.

We report a "momentum transfer" X-ray diffraction data analysis approach to nondestructive determination of the shape of an average nano-particle in three dimensions. The possibility of using incoherent X-ray sources allows the method to be implemented in any laboratory. Our results demonstrate that this approach to X-ray diffraction data analysis provides the potential for 3D reconstruction without a tomographic synthesis of 2D images, as in conventional coherent radiation imaging experiments. A simple and robust quantitative technique to reconstruct an average nano-particle randomly dispersed over a large volume within a sample, such as presented here, should enable researchers to study nano-particles using conventional laboratory X-ray diffraction equipment with resolution up to a few nanometers.

Quantitative phase analysis of cementitious materials is crucial for understanding and predicting their performance. For anhydrous Portland cements, a variety of techniques based on microscopy, spectroscopy, and diffraction exist. Here, we employ two highly diverse techniques (X-ray Diffraction and Raman Imaging) to a common sample (ASTM Type I/II OPC). We find that, firstly, the two methods are highly complementary in the initial phase identification, given that certain clinker phases are difficult to detect in one as opposed to the other. Secondly, quantitative analysis can be influenced by parameters such as preferred orientation, order of phase addition, and the nature of the binarization algorithm. Specific signal-to-noise (SNT = 5) and epoxy-to-signal (EST = 10) thresholds resulted in the highest alignment between the two methods (R2 > 0.99, Δwt% < 2.5 %). Thirdly, Raman imaging area can be reliably reduced (25 mm2 to 9 mm2) to shorten scan time by 2.5× (8 h to 3 h).

X-ray diffraction(XRD) is an essential characterization technique to study the properties of the materials. Finding a material's crystal system is an important step in its analysis. So, the process should be fast as well as accurate. In total there are seven crystal systems: triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic. Previous studies have worked on finding the material crystal structure by introducing machine learning approaches. In, recent studies the X-ray diffraction(XRD) dataset in the tabular form was used to train a machine learning model to classify the material's crystal system. The machine learning models trained on the tabular X-ray diffraction(XRD) dataset didn't maximize their performance. In the scope of this study rendered X-ray diffraction(XRD) images had been used to maximize the performance of the machine learning models. By using the rendered images as input from the X-ray diffraction(XRD) tabular dataset the machine learning model was able to achieve an accuracy of 98%-99%. The final findings had shown that rendered images datasets had improved the machine learning model's ability to correctly classify the crystal systems of materials.

Calculation of four‐dimensional (4D) dose distributions requires the remapping of dose calculated on each available binned phase of the 4D CT onto a reference phase for summation. Deformable image registration (DIR) is usually used for this task, but unfortunately almost always considers only endpoints rather than the whole motion path. A new algorithm, 4D tissue deformation reconstruction (4D TDR), that uses either CT projection data or all available 4D CT images to reconstruct 4D motion data, was developed. The purpose of this work is to verify the accuracy of the fit of this new algorithm using a realistic tissue phantom. A previously described fresh tissue phantom with implanted electromagnetic tracking (EMT) fiducials was used for this experiment. The phantom was animated using a sinusoidal and a real patient‐breathing signal. Four‐dimensional computer tomography (4D CT) and EMT tracking were performed. Deformation reconstruction was conducted using the 4D TDR and a modified 4D TDR which takes real tissue hysteresis (4D TDRHysteresis) into account. Deformation estimation results were compared to the EMT and 4D CT coordinate measurements. To eliminate the possibility of the high contrast markers driving the 4D TDR, a comparison was made using the original 4D CT data and data in which the fiducials were electronically masked. For the sinusoidal animation, the average deviation of the 4D TDR compared to the manually determined coordinates from 4D CT data was 1.9 mm, albeit with as large as 4.5 mm deviation. The 4D TDR calculation traces matched 95% of the EMT trace within 2.8 mm. The motion hysteresis generated by real tissue is not properly projected other than at endpoints of motion. Sinusoidal animation resulted in 95% of EMT measured locations to be within less than 1.2 mm of the measured 4D CT motion path, enabling accurate motion characterization of the tissue hysteresis. The 4D TDRHysteresis calculation traces accounted well for the hysteresis and matched 95% of the EMT trace within 1.6 mm. An irregular (in amplitude and frequency) recorded patient trace applied to the same tissue resulted in 95% of the EMT trace points within less than 4.5 mm when compared to both the 4D CT and 4D TDRHysteresis motion paths. The average deviation of 4D TDRHysteresis compared to 4D CT datasets was 0.9 mm under regular sinusoidal and 1.0 mm under irregular patient trace animation. The EMT trace data fit to the 4D TDRHysteresis was within 1.6 mm for sinusoidal and 4.5 mm for patient trace animation. While various algorithms have been validated for end‐to‐end accuracy, one can only be fully confident in the performance of a predictive algorithm if one looks at data along the full motion path. The 4D TDR, calculating the whole motion path rather than only phase‐ or endpoints, allows us to fully characterize the accuracy of a predictive algorithm, minimizing assumptions. This algorithm went one step further by allowing for the inclusion of tissue hysteresis effects, a real‐world effect that is neglected when endpoint‐only validation is performed. Our results show that the 4D TDRHysteresis correctly models the deformation at the endpoints and any intermediate points along the motion path.PACS numbers: 87.55.km, 87.55.Qr, 87.57.nf, 87.85.Tu

3D Multi-modal Imaging of demineralised dentine using combined synchrotron µ-XRD-CT and STXM-CT.

Effect of cooling rate on residual stress and mechanical properties of laser remelted ceramic coating

The structures of a series of 3D-SBA-15 materials have been systematically studied by X-ray diffraction (XRD), nitrogen sorption, and electron tomography (ET) techniques. All the 3D-SBA-15 materials possess an ordered 2D hexagonal mesostructure with similar cell parameters, while the pore size measured from nitrogen sorption increases with the hydrothermal treatment temperature, in some cases even larger than the cell parameter calculated from X-ray diffraction. Taking advantage of the ET technique, it is shown that there exist two types of pores in 3D-SBA-15 materials: one is the ordered channels associated with the hexagonal symmetry, and the other is locally disordered and randomly distributed merged pores. During the hydrothermal treatment events at various temperatures, the size of ordered channels changes little, while the volume fraction and the overall size of the latter type of pores increase and eventually become dominant. Thus, the attribution of the pore sizes obtained from nitrogen sorption analysis to which types of pores is synthesis condition dependent and ET is an important tool to answer this question.

Strain tensor measurements are important for understanding elastic and plastic deformation, but full bulk strain tensor measurement techniques are still lacking, in particular for dynamic loading. Here, such a methodology is reported, combining imaging-based strain field mapping and simultaneous X-ray diffraction for four typical loading modes: one-dimensional strain/stress compression/tension. Strain field mapping resolves two in-plane principal strains, and X-ray diffraction analysis yields volumetric strain, and thus the out-of-plane principal strain. This methodology is validated against direct molecular dynamics simulations on nanocrystalline tantalum. This methodology can be implemented with simultaneous X-ray diffraction and digital image correlation in synchrotron radiation or free-electron laser experiments.

A new friction processing method for welding of dissimilar metals