Direct X-ray Imaging Research Articles

3D Nanoprinted Plastic Kinoform X-Ray Optics.

High-performance focusing of X-rays requires the realization of very challenging 3D geometries with nanoscale features, sub-millimeter-scale apertures, and high aspect ratios. A particularly difficult structure is the profile of an ideal zone plate called a kinoform, which is manufactured in nonideal approximated patterns, nonetheless requires complicated multistep fabrication processes. Here, 3D fabrication of high-performance kinoforms with unprecedented aspect ratios out of low-loss plastics using femtosecond two-photon 3D nanoprinting is presented. A thorough characterization of the 3D-printed kinoforms using direct soft X-ray imaging and ptychography demonstrates superior performance with an efficiency reaching up to 20%. An extended concept is proposed for on-chip integration of various X-ray optics toward high-fidelity control of X-ray wavefronts and ultimate efficiencies even for harder X-rays. Initial results establish new, advanced focusing optics for both synchrotron and laboratory sources for a large variety of X-ray techniques and applications ranging from materials science to medicine.

The comparison of point-of-care ultrasonography and radiography in the diagnosis of tibia and fibula fractures

ObjectiveWe aimed to compare the efficacy of Point-of-care ultrasonography (POCUS) with radiography in the diagnosis of tibia fracture (TF) and fibula fracture (FF), and determation of fracture characteristics. MethodsPatients aged 5–55 years who were admitted to ED due to low-energy, simple extremity trauma, who had a suspected TF and FF on physical examination were included in this prospective study. One physician performed POCUS examination. Other physician evaluated the radiography images. The obtained results were compared. ResultsA total of 62 patients were included in the study. TF was detected in 21 patients by radiography and in 24 patients by POCUS. FF was detected in 24 patients by radiography and in 25 patients by POCUS. Ten of the patients had both TF and FF. Compared with radiography, sensitivity, specificity, PPV and NPV of POCUS in the detection of TF were 100%, 93%, 88% and 100% (95% CI, 91–100%), respectively. Compared with direct X-ray imaging, sensitivity, specificity, PPV and NPV of POCUS in the detection of FF were 100%, 97%, 96% and 100% (95% CI, 96–100%), respectively. We determined that POCUS is also successful in detection of fracture features such as angulation, step-off, extension into the joint space that can determine the treatment decision. ConclusionThis study demonstrated that POCUS was found to be as successful as direct X-ray imaging in the diagnosis of TF and FF.

A-Si:H TFT-Silicon Hybrid Low-Energy X-Ray Detector

Direct conversion crystalline silicon X-ray imagers are used for low-energy X-ray photon (4–20 keV) detection in scientific research applications such as protein crystallography. In this paper, we demonstrate a novel pixel architecture that integrates a crystalline silicon X-ray detector with a thin-film transistor amorphous silicon pixel readout circuit. We describe a simplified two-mask process to fabricate a complete imaging array and present preliminary results that show the fabricated pixel to be sensitive to 5.89-keV photons from a low activity Fe-55 gamma source. This paper presented can expedite the development of high spatial resolution, low cost, direct conversion imagers for X-ray diffraction and crystallography applications.

Direct X-Ray Imaging as a Tool for Understanding Multiphysics Phenomena in Energy Storage

The lithium-ion battery (LIB) has emerged as a key energy storage device for a wide range of applications, from consumer electronics to transportation. While LIBs have made key advancements in these areas, limitations remain for Li-ion batteries with respect to affordability, performance, and reliability. These challenges have encouraged the exploration for more advanced materials and novel chemistries to mitigate these limitations. The continued development of Li-ion and other advanced batteries is an inherently multiscale problem that couples electrochemistry, transport phenomena, mechanics, microstructural morphology, and device architecture. Observing the internal structure of batteries, both ex situ and during operation, provides a critical capability for further advancement of energy storage technology. X-ray imaging has been implemented to provide further insight into the mechanisms governing Li-ion batteries through several 2D and 3D techniques. Ex situ imaging has yielded microstructural data from both anode and cathode materials, providing insight into mesoscale structure and composition. Furthermore, since X-ray imaging is a nondestructive process studies have been conducted in situ and in operando to observe the mechanisms of operation as they occur. Data obtained with these methods has also been integrated into multiphysics models to predict and analyze electrode behavior. The following paper provides a brief review of X-ray imaging work related to Li-ion batteries and the opportunities these methods provide for the direct observation and analysis of the multiphysics behavior of battery materials.

FOXSI-2: Upgrades of the Focusing Optics X-ray Solar Imager for its Second Flight

The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload flew for the second time on 2014 December 11. To enable direct Hard X-Ray (HXR) imaging spectroscopy, FOXSI makes use of grazing-incidence replicated focusing optics combined with fine-pitch solid-state detectors. FOXSI’s first flight provided the first HXR focused images of the Sun. For FOXSI’s second flight several updates were made to the instrument including updating the optics and detectors as well as adding a new Solar Aspect and Alignment System (SAAS). This paper provides an overview of these updates as well as a discussion of their measured performance.

Real-time direct and diffraction X-ray imaging of irregular silicon wafer breakage.

Fracture and breakage of single crystals, particularly of silicon wafers, are multi-scale problems: the crack tip starts propagating on an atomic scale with the breaking of chemical bonds, forms crack fronts through the crystal on the micrometre scale and ends macroscopically in catastrophic wafer shattering. Total wafer breakage is a severe problem for the semiconductor industry, not only during handling but also during temperature treatments, leading to million-dollar costs per annum in a device production line. Knowledge of the relevant dynamics governing perfect cleavage along the {111} or {110} faces, and of the deflection into higher indexed {hkl} faces of higher energy, is scarce due to the high velocity of the process. Imaging techniques are commonly limited to depicting only the state of a wafer before the crack and in the final state. This paper presents, for the first time, in situ high-speed crack propagation under thermal stress, imaged simultaneously in direct transmission and diffraction X-ray imaging. It shows how the propagating crack tip and the related strain field can be tracked in the phase-contrast and diffracted images, respectively. Movies with a time resolution of microseconds per frame reveal that the strain and crack tip do not propagate continuously or at a constant speed. Jumps in the crack tip position indicate pinning of the crack tip for about 1-2 ms followed by jumps faster than 2-6 m s(-1), leading to a macroscopically observed average velocity of 0.028-0.055 m s(-1). The presented results also give a proof of concept that the described X-ray technique is compatible with studying ultra-fast cracks up to the speed of sound.

Replacement of Vertebral Lamina (Laminoplasty) in Surgery for Lumbar Isthmic Spondylolisthesis: 5-Year Follow-Up Results.

Study DesignA review of clinical and radiological outcomes of lumbar laminoplasty (LL) for the treatment of isthmic spondylolisthesis (ISL).PurposeThe single session performance of posterior lumbar interbody fusion with allograft in the anterior column and providing the realignment of the vertebrae was presented as a preliminary report earlier.Overview of LiteratureLong-term surgical outcome of cervical laminoplasty in patients has been reported. But, outcome of LL in patients is unclear.MethodsThe long-term (5 years) year follow-up results of the LL technique are reported in this retrospective study. All patients underwent preoperative and postoperative direct X-ray, computed tomography, and magnetic resonance imaging. The patients that did not respond to conservative treatment were operated. Twenty-one (52.5%) female and 19 (47.5%) male patients were included.ResultsMean age was 43,5 years (ranges, 22–57 years). The most common symptoms were low back pain (89%), pelvic and leg pain (69%) and reduction in walking distance (65%). A total of 180 pedicle screws were inserted in 40 patients; posterior lumbar interbody fusion and laminoplasty with reduction was performed in 20 patients for L4–L5, 12 patients for L5–S1, 4 patients for L3–L4–L5 and 4 patients for L4–L5-S1. Ten (25%) patients with ILL had accompanying spinal stenosis. The difference between preoperative and postoperative sagittal plane rotation and dislocation degrees and disc space heights were statistically significant in all patients (p<0.05). Solid grade 4 fusion was observed in 38 patients; in only 2 patients grade 2 pseudoarthrosis developed (5%), but these patients were asymptomatic. Visual analog scale, Prolo economical and functional scale was examined with an average follow-up 5.5 years.ConclusionsLL technique has the advantages of shorter duration of operation, lack of graft donor site complications, protection of posterior column osseoligamentous structures and achievement of high fusion rates in one session.

Removal of a missed guide wire in central vein with endovascular intervention: a case report

Cardiovascular Surgery and Interventions publishes original articles on topics in cardiovascular surgery, cardiovascular anesthesia and cardiology. These encompass all relevant clinical, surgical and laboratory studies, editorials, current and collective reviews, technical know-how papers, case reports, interesting images, “How to Do It” papers, correspondence and commentary.

Experimental characterization of a 10 μW 55 μm-pitch FPN-compensated CMOS digital pixel sensor for X-ray imagers

This paper presents experimental results obtained from both electrical and radiation tests of a new room-temperature digital pixel sensor (DPS) circuit specifically optimized for digital direct X-ray imaging. The 10μW 55μm-pitch CMOS active pixel circuit under test includes self-bias capability, built-in test, selectable e−/h+ collection, 10-bit charge-integration A/D conversion, individual gain tuning for fixed pattern noise (FPN) cancellation, and digital-only I/O interface, which make it suitable for 2D modular chip assemblies in large and seamless sensing areas. Experimental results for this DPS architecture in 0.18μm 1P6M CMOS technology are reported, returning good performance in terms of linearity, 2kerms− of ENC, inter-pixel crosstalk below 0.5LSB, 50Mbps of I/O speed, and good radiation response for its use in digital X-ray imaging.

A marker-based watershed method for X-ray image segmentation

Digital X-ray images are the most frequent modality for both screening and diagnosis in hospitals. To facilitate subsequent analysis such as quantification and computer aided diagnosis (CAD), it is desirable to exclude image background. A marker-based watershed segmentation method was proposed to segment background of X-ray images. The method consisted of six modules: image preprocessing, gradient computation, marker extraction, watershed segmentation from markers, region merging and background extraction. One hundred clinical direct radiograph X-ray images were used to validate the method. Manual thresholding and multiscale gradient based watershed method were implemented for comparison. The proposed method yielded a dice coefficient of 0.964±0.069, which was better than that of the manual thresholding (0.937±0.119) and that of multiscale gradient based watershed method (0.942±0.098). Special means were adopted to decrease the computational cost, including getting rid of few pixels with highest grayscale via percentile, calculation of gradient magnitude through simple operations, decreasing the number of markers by appropriate thresholding, and merging regions based on simple grayscale statistics. As a result, the processing time was at most 6s even for a 3072×3072 image on a Pentium 4 PC with 2.4GHz CPU (4 cores) and 2G RAM, which was more than one time faster than that of the multiscale gradient based watershed method. The proposed method could be a potential tool for diagnosis and quantification of X-ray images.

菲涅耳波带板X射线成像的快速计算方法

Direct X-ray imaging using a Fresnel zone plate (FZP) in the applications of laser plasma or inertial confinement fusion diagnostics has the potential for realizing high spatial resolution in the range of micrometers to sub-micrometers. For such an FZP imaging, the influences of the object size and the spectral bandwidth of the illuminating light have to be considered. In the simulations, numerical calculations such as the Fresnel-Kirchhhoff diffraction integral and convolutions have to be done, which will take a large amount of computer memories and cost a lot of computing time. In this paper we report improved algorithms for these numerical calculations by adopting the Monte-Carlo integration and a new algorithm of convolution. By simulating the two-dimensional imaging of an extended polychromatic X-ray source, it shows that the new algorithm has significant advantages in reducing the computing time over the past algorithms, and thus such simulations can be done by a desktop computer. The imaging indicates that with the increase of the object size and/or the spectral bandwidth, the image background is enhanced which causes the decrease of the contrast and also the image quality.

Chromospheric evaporation in sympathetic coronal bright points

{Chromospheric evaporation is a key process in solar flares that has extensively been investigated using the spectroscopic observations. However, direct soft X-ray (SXR) imaging of the process is rare, especially in remote brightenings associated with the primary flares that have recently attracted dramatic attention.} {We intend to find the evidence for chromospheric evaporation and figure out the cause of the process in sympathetic coronal bright points (CBPs), i.e., remote brightenings induced by the primary CBP.} {We utilise the high-cadence and high-resolution SXR observations of CBPs from the X-ray Telescope (XRT) aboard the Hinode spacecraft on 2009 August 23.} {We discover thermal conduction front propagating from the primary CBP, i.e., BP1, to one of the sympathetic CBPs, i.e., BP2 that is 60$\arcsec$ away from BP1. The apparent velocity of the thermal conduction is $\sim$138 km s$^{-1}$. Afterwards, hot plasma flowed upwards into the loop connecting BP1 and BP2 at a speed of $\sim$76 km s$^{-1}$, a clear signature of chromospheric evaporation. Similar upflow was also observed in the loop connecting BP1 and the other sympathetic CBP, i.e., BP3 that is 80$\arcsec$ away from BP1, though less significant than BP2. The apparent velocity of the upflow is $\sim$47 km s$^{-1}$. The thermal conduction front propagating from BP1 to BP3 was not well identified except for the jet-like motion also originating from BP1.} {We propose that the gentle chromospheric evaporation in the sympathetic CBPs were caused by thermal conduction originating from the primary CBP.}

Structural and electrical properties of polycrystalline CdTe films for direct X-ray imaging detectors

We introduce polycrystalline cadmium telluride (CdTe) with high atomic number and density, low effective energy and wide band gap for application in large area diagnostic X-ray digital imaging. In this work, polycrystalline CdTe films were fabricated on ITO/glass substrate by both physical vapor deposition (PVD) with slow deposition rate and pressure of 10−6Torr and the closed space sublimation (CSS) method with high deposition rate and low vacuum pressure(10−2Torr). The various polycrystalline CdTe films were grown at different deposition rates and substrate temperatures. Physical properties such as microstructures and the crystal structure of the polycrystalline samples were investigated by SEM and XRD patterns respectively. The PVD method resulted in microstructures with columnar shape and more uniform surface, while the CSS method produced microstructures with many larger grains and less uniform surface. The films were polycrystalline structures with a preferential (111) direction. The electrical and optical properties such as the dark current as a function of applied bias voltage and X-ray sensitivity of the fabricated films were measured and investigated under X-ray exposure.

Analysis of direct oil contrast lymphography of upper limb lymphatics traversing the axilla – A lesson from the past – Contribution to the concept of axillary reverse mapping

IntroductionAxillary reverse mapping (ARM) is a method to preserve upper extremity (UE) lymphatics during axillary surgery in breast cancer patients. This may reduce the incidence of lymphedema. Very precise method to demonstrate lymphatic drainage is direct X-ray lymphography. Materials and methodsThe evaluation of direct lymphography X-ray images of the axilla and proximal part of the upper extremity was performed in 9 subjects. As contrast was used Lipiodoil injected on the dorsal side of hand. ResultsThe lymph from UE is drained by 2–4 main afferent collectors, which in 5 of 9 cases entered into one node in the lateral axilla (ARM node). This node was considered to be the sentinel lymph node for the UE. In 4 cases a cranial collector was shown, which led directly to nodes in the upper part of the axilla. This collector had numerous anastomoses with other collectors before entering the axillary nodes. The most important finding is the demonstration of numerous lymphatic anastomoses that take place between all imaged nodes in the axilla including the caudal nodes, which is the most frequent localization of the breast sentinel lymph node. ConclusionThe relationship of lymphatic drainage of the UE and breast are closely related and share numerous connections. These connections represent the main problem of the ARM concept because they may pose potencional route for metastatic cancer cells in sentinel node positive breast cancer patients. Further studies are necessary to improve understanding of this method.Axillary reverse mapping – breast cancer – lymphedema – sentinel node biopsy.

Development and evaluation of gallium nitride-based thin films for x-ray dosimetry

X-ray radiation plays an important role in medical procedures ranging from diagnostics to therapeutics. Due to the harm such ionizing radiation can cause, it has become common practice to closely monitor the dosages received by patients. To this end, precise online dosimeters have been developed with the dual objectives of monitoring radiation in the region of interest and improving therapeutic methods. In this work, we evaluate GaN thin film high electron mobility heterostructures with sub-mm2 detection areas as x-ray radiation detectors. Devices were tested using 40–300 kV Bremsstrahlung x-ray sources. We find that the photoconductive device response exhibits a large gain, is almost independent of the angle of irradiation, and is constant to within 2% of the signal throughout this medical diagnostic x-ray range, indicating that these sensors do not require recalibration for geometry or energy. Furthermore, the devices show a high sensitivity to x-ray intensity and can measure in the air kerma rate (free-in-air) range of 1 µGy s−1 to 10 mGy s−1 with a signal stability of ±1% and a linear total dose response over time. Medical conditions were simulated by measurements of device responses to irradiation through human torso phantoms. Direct x-ray imaging is demonstrated using the index finger and wrist sections of a human phantom. The results presented here indicate that GaN-based thin film devices exhibit a wide range of properties, which make them promising candidates for dosimetry applications. In addition, with potential detection volumes smaller than 10−6 cm3, they are well suited for high-resolution x-ray imaging. Moreover, with additional engineering steps, these devices can be adapted to potentially provide both in vivo biosensing and x-ray dosimetry.

Wear Resistance and Microstructural Study of Diamond Coated WC Tools

Diamond composite materials are classified as superhard and exhibit exceptional abrasive resistance. Cemented tungsten carbide tools with a thick coating of diamond composite material (PCD) are finding increased usage in materials cutting operations in manufacturing, mining, minerals, gas and petroleum exploration and civil construction industries. Two major advantages derived from these coated tools are: (a) increased wear resistance and hence increased life-span of these tools and (b) their proven ability to handle “difficult-to-machine” materials as well as high-strength, extremely abrasive materials such as quartz-rich rocks, granites and basalts. In this research, the variability of the wear resistance of PCD coated tungsten carbide is correlated with microstructural variations. A detailed study of the microstructure and distribution of phases was performed using SEM, cathodoluminescence (CL) imaging, direct x-ray imaging, Raman spectroscopy as well as residual stress measurements using neutron diffraction.

Reduced photocurrent lag using unipolar solid-state photoconductive detector structures: Application to stabilized n-i-p amorphous selenium

Memory effects in direct detection solid-state photoconductors are attributed to interrupted charge transport by traps in the bulk and result in persistent photocurrent lag and ghosting. The identified sources for image lag following the cessation of x-ray exposure are the inhomogeneous electric field’s spatial distribution and the detrapping of the bulk space charge. This work shows that the latter is the dominant mechanism for the persistent photocurrent lag in stabilized n-i-p amorphous selenium photoconductors and proposes unipolar charge-sensing detector design for reducing image lag and improving the temporal performance of direct conversion x-ray imagers.

Chapter 1: Diagnostic Medical Imaging: X-ray projection technique, image subtraction method, direct digital x-ray imaging, computed tomography (CT)

Chapter 1: Diagnostic Medical Imaging: X-ray projection technique, image subtraction method, direct digital x-ray imaging, computed tomography (CT)

Tests of monolithic active pixel sensors at national synchrotron light source

The paper discusses basic characterization of Monolithic Active Pixel Sensors (MAPS) carried out at the X12A beam-line at National Synchrotron Light Source (NSLS), Upton, NY, USA. The tested device was a MIMOSA V (MV) chip, back-thinned down to the epitaxial layer. This 1M pixels device features a pixel size of 17 × 17 μ m 2 and was designed in a 0.6 μ m CMOS process. The X-ray beam energies used range from 5 to 12 keV. Examples of direct X-ray imaging capabilities are presented.

Feasibility of HgBrI as photoconductor for direct X-ray imaging

Films of HgBrI (eutectic composition) were grown by the physical vapor deposition method on palladium-coated glass substrates 2''times2'' in size. The growth was performed in a system especially designed and constructed for getting a fine control of the growth parameters. The best growth conditions were a source temperature of 116degC, a growth temperature of 40degC and a growth time of 3 h, with an initial pressure of 6times10-3 Pa. Film thicknesses and grain sizes gave values ranging between 100 and 350 mum (10%), and between (10plusmn5) and (50plusmn20) mum, respectively. The dark current density of the films is higher than 10 pA/mm2 (maximum value required for the application) for electric fields above 0.03 V/mum, and the resistivity is 3.8times1011 Omega.cm. Electron and hole mobility-lifetimes of 7.1times10-6 cm2/V y 1.0times10-5 cm2/V were estimated. HgBrI films give a sensitivity to X-rays of 65 nC/Rmiddotcm2 for an X-ray beam of 70 KVp, with an electric field of 0.25 V/mum applied to the film. Taking into account that this is the first attempt on growing films with this material, these results indicate HgBrI as a new compound semiconductor candidate for the application