PEPI Lab: a flexible compact multi-modal setup for X-ray phase-contrast and spectral imaging

This paper presents a new flexible compact multi-modal imaging setup referred to as PEPI (Photon-counting Edge-illumination Phase-contrast imaging) Lab, which is based on the edge-illumination (EI) technique and a chromatic detector. The system enables both X-ray phase-contrast (XPCI) and spectral (XSI) imaging of samples on the centimeter scale. This work conceptually follows all the stages in its realization, from the design to the first imaging results. The setup can be operated in four different modes, i.e. photon-counting/conventional, spectral, double-mask EI, and single-mask EI, whereby the switch to any modality is fast, software controlled, and does not require any hardware modification or lengthy re-alignment procedures. The system specifications, ranging from the X-ray tube features to the mask material and aspect ratio, have been quantitatively studied and optimized through a dedicated Geant4 simulation platform, guiding the choice of the instrumentation. The realization of the imaging setup, both in terms of hardware and control software, is detailed and discussed with a focus on practical/experimental aspects. Flexibility and compactness (66 cm source-to-detector distance in EI) are ensured by dedicated motion stages, whereas spectral capabilities are enabled by the Pixirad-1/Pixie-III detector in combination with a tungsten anode X-ray source operating in the range 40-100 kVp. The stability of the system, when operated in EI, has been verified, and drifts leading to mask misalignment of less than 1 [Formula: see text]m have been measured over a period of 54 h. The first imaging results, one for each modality, demonstrate that the system fulfills its design requirements. Specifically, XSI tomographic images of an iodine-based phantom demonstrate the system's quantitativeness and sensibility to concentrations in the order of a few mg/ml. Planar XPCI images of a carpenter bee specimen, both in single and double-mask modes, demonstrate that refraction sensitivity (below 0.6 [Formula: see text]rad in double-mask mode) is comparable with other XPCI systems based on microfocus sources. Phase CT capabilities have also been tested on a dedicated plastic phantom, where the phase channel yielded a 15-fold higher signal-to-noise ratio with respect to attenuation

Development of a two-dimensional virtual pixel X-ray imaging detector for time-resolved structure research

An interpolating two-dimensional X-ray imaging detector based on a single photon counter with gas amplification by GEM (gas electron multiplier) structures is presented. The detector system can be used for time-resolved structure research down to the microsecond-time domain. The prototype detector has been tested at the SAXS beamline at ELETTRA synchrotron light source with a beam energy of 8 keV to test its capabilities in the rough beamline environment. The imaging performance is examined with apertures and standard diffraction targets. Finally, the application in a time-resolved lipid temperature jump experiment is presented.Comment: 10 pages, 14 figures, accepted for publication in J. Synchrotron Rad, revised version, paper shortened, minor change

Imaging with high Dynamic using an Ionization Chamber

In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. The combination between gas gain operations and integrating front-end electronics yields a dynamic range as high as eight to nine orders of magnitude. Therefore this device is well suitable for medical imaging or applications such as small angle x-ray scattering, where the requirements on the dynamic of the detector are exceptional high. Basically the described detector is an ionization chamber adapted to fan beam geometry with an active area of 192 cm and a pitch of the anode strips of 150 micrometer. In the vertical direction beams as high as 10 mm can be accepted. Every read-out strip is connected to an analogue integrating electronics channel realized in a custom made VLSI chip. A MicroCAT structure utilized as a shielding grid enables frame rates as high as 10kHz. The high dynamic range observed stems from the fact that the MicroCAT enables active electron amplification in the gas. Thus a single photon resolution can be obtained for low photon fluxes even with the integrating electronics. The specialty of this device is that for each photon flux the gas amplification can be adjusted in such a fashion that the maximum DQE value is achieved.Comment: 7 pages, 12 figures, distilled by OpenOffice.org 3.

Characterization of the transient response of diamond sensors to collimated, sub-ps, 1 GeV electron bunches

Diamond sensors (DS) are widely used as solid-state particle detectors, beam loss monitors, and dosimeters in high-radiation environments, e.g., particle colliders. We have calibrated our DS with steady β - and X-radiation, spanning a dose rate in the range 0.1-100 mGy/s. Here, we report the first systematic characterization of transient responses of DS to collimated, sub-picosecond, 1 GeV electron bunches. These bunches, possessing a charge ranging from tens to hundreds of pC and a size from tens of microns to millimeters, are suitably provided by the FERMI electron linac in Trieste, Italy. The high density of charge carriers generated by ionization in the diamond bulk causes a transient modification of electrical properties of DS (e.g., resistance), which in turn affects the signal shape. We have modeled a two-step numerical approach, simulating the effects on the signal of both the evolution of charge carrier density in the diamond bulk and the changes in the circuit parameters. This approach interprets features observed in our experimental results to a great extent

X-ray detection of structural orientation in human articular cartilage

AbstractObjective: To determine the feasibility of detecting the structural orientation in cartilage with Diffraction Enhanced X-Ray Imaging.Design: Human tali and femoral head specimens were Diffraction Enhanced X-Ray Imaged (DEI) at the SYRMEP beamline at Elettra at various energy levels to detect the architectural arrangement of collagen within cartilage. DEI utilizes a monochromatic and highly collimated beam, with an analyzer crystal that selectively weights out photons according to the angle they have been deviated with respect to the original direction. This provides images of very high contrast, and with the rejection of X-ray scatter.Results: DEI allowed the visualization of articular cartilage and a structural orientation, resembling arcades, within.Conclusion: Our diffraction enhanced images represent the first radiographic detection of the structural orientation in cartilage. Our data are in line with previous studies on the structural organization of joint cartilage. They confirm the model of a vaulting system of collagen fiber bundles interrupted by proteoglycan aggregates

Tomographic phase and attenuation extraction for a sample composed of unknown materials using X-ray propagation-based phase-contrast imaging

Propagation-based phase-contrast X-ray imaging (PB-PCXI) generates image contrast by utilizing sample-imposed phase-shifts. This has proven useful when imaging weakly-attenuating samples, as conventional attenuation-based imaging does not always provide adequate contrast. We present a PB-PCXI algorithm capable of extracting the X-ray attenuation, $\beta$, and refraction, $\delta$, components of the complex refractive index of distinct materials within an unknown sample. The method involves curve-fitting an error-function-based model to a phase-retrieved interface in a PB-PCXI tomographic reconstruction, which is obtained when Paganin-type phase-retrieval is applied with incorrect values of $\delta$ and $\beta$. The fit parameters can then be used to calculate true $\delta$ and $\beta$ values for composite materials. This approach requires no a priori sample information, making it broadly applicable. Our PB-PCXI reconstruction is single distance, requiring only one exposure per tomographic angle, which is important for radiosensitive samples. We apply this approach to a breast-tissue sample, recovering the refraction component, $\delta$, with 0.6 - 2.4\% accuracy compared to theoretical values.Comment: 8 pages, 4 figures and 1 tabl

High contrast microstructural visualization of natural acellular matrices by means of phase-based x-ray tomography

Acellular scaffolds obtained via decellularization are a key instrument in regenerative medicine both per se and to drive the development of future-generation synthetic scaffolds that could become available off-the-shelf. In this framework, imaging is key to the understanding of the scaffolds\u2019 internal structure as well as their interaction with cells and other organs, including ideally post-implantation. Scaffolds of a wide range of intricate organs (esophagus, lung, liver and small intestine) were imaged with x-ray phase contrast computed tomography (PC-CT). Image quality was sufficiently high to visualize scaffold microarchitecture and to detect major anatomical features, such as the esophageal mucosal-submucosal separation, pulmonary alveoli and intestinal villi. These results are a long-sought step for the field of regenerative medicine; until now, histology and scanning electron microscopy have been the gold standard to study the scaffold structure. However, they are both destructive: hence, they are not suitable for imaging scaffolds prior to transplantation, and have no prospect for post-transplantation use. PC-CT, on the other hand, is non-destructive, 3D and fully quantitative. Importantly, not only do we demonstrate achievement of high image quality at two different synchrotron facilities, but also with commercial x-ray equipment, which makes the method available to any research laboratory

AC/DC: The FERMI FEL Split and Delay Optical Device for Ultrafast X-ray Science

Free-electron lasers (FELs) are the most advanced class of light-sources, by virtue of their unique capability to lase high-brightness pulses characterized by wavelengths spanning the extreme-ultraviolet, the soft and hard X-ray spectral domains, as well as by temporal lengths lying in the femtosecond (fs) timescale. The next step to push the current standards in ultrafast X-ray science is strongly linked to the possibility of engineering and exploiting time-resolved experiments exclusively for FELs pulses, ideally having different colors tunable at specific electronic resonance of the chemical elements. At the seeded FERMI FEL (Trieste, Italy) this goal is committed to the optical device known as AC/DC, which stands for the auto correlator/delay creator. AC/DC is designed to double the incoming FEL pulse splitting the photon beam by inserting a grazing incidence flat mirror, thus preserving the spectral and temporal properties, and further delaying one of these two pulses in time. It can independently tune the FEL pulses fluence on the two optical paths by means of solid-state filters, too. Here, we present a detailed description about this optical device. Strong emphasis is dedicated to the AC/DC opto-mechanical design and to the laser-based feedback systems implemented to compensate for any mismatch affecting the FEL optical trajectory, ascribable to both mechanical imperfections and paraxial errors rising during a temporal delay scan

An IAEA Multi-technique X-ray Spectrometry End-station at Elettra Sincrotrone Trieste: Benchmarking Results and Interdisciplinary Applications

The International Atomic Energy Agency (IAEA) jointly with the Elettra Sincrotrone Trieste (EST) operates a multipurpose X-ray spectrometry endstation at the X-ray Fluorescence beamline (10.1L). The facility has been available to external users since the beginning of 2015 through the peer-review process of EST. Using this collaboration framework, the IAEA supports and promotes synchrotron-radiation-based research and training activities for various research groups from the IAEA Member States, especially those who have limited previous experience and resources to access a synchrotron radiation facility. This paper aims to provide a broad overview about various analytical capabilities, intrinsic features and performance figures of the IAEA X-ray spectrometry endstation through the measured results. The IAEA-EST endstation works with monochromatic X-rays in the energy range 3.7-14keV for the Elettra storage ring operating at 2.0 or 2.4GeV electron energy. It offers a combination of different advanced analytical probes, e.g. X-ray reflectivity, X-ray absorption fine-structure measurements, grazing-incidence X-ray fluorescence measurements, using different excitation and detection geometries, and thereby supports a comprehensive characterization for different kinds of nanostructured and bulk materials.A broad overview of the various analytical capabilities, intrinsic features and performance figures of the IAEA X-ray spectrometry endstation operated at the X-ray Fluorescence beamline of Elettra Sincrotrone Trieste is given, and different applications are demonstrated to familiarize the user community with the applicable intersdisciplinary research.Fil: Karydas, A.. International Atomic Energy Agency; Austria. National Centre for Scientific Research "Demokritos"; GreciaFil: Czyzycki, M.. International Atomic Energy Agency; Austria. AGH University of Science and Technology. Faculty of Physics and Applied Computer Science ; PoloniaFil: Leani, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. International Atomic Energy Agency; AustriaFil: Migliori, A.. International Atomic Energy Agency; Austria. Nuclear Spectrometry And Appications Lab, Iaea. Onu; AustriaFil: Osán, J.. Hungarian Academy of Sciences Centre for Energy Research; Hungría. International Atomic Energy Agency; AustriaFil: Bogovac, M.. International Atomic Energy Agency; AustriaFil: Wrobel, P.. AGH University of Science and Technology. Faculty of Physics and Applied Computer Science ; PoloniaFil: Vakula, N.. International Atomic Energy Agency; AustriaFil: Padilla Alvarez, R.. International Atomic Energy Agency; AustriaFil: Menk, Ralf Hendrik. Elettra-Sincrotrone Trieste SCpA di Interesse Nazionale; Italia. University of Saskatchewan; CanadáFil: Gol, M. G.. Iranian Light Source Facility; IránFil: Antonelli, M.. Istituto Nazionale di Fisica Nucleare; Italia. Elettra-Sincrotrone Trieste SCpA di Interesse Nazionale; ItaliaFil: Tiwari, M. K.. Raja Ramanna Centre for Advanced Technology; IndiaFil: Caliri, C.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Vogel Mikuš, K.. Jozef Stefan Institute; Eslovenia. University of Ljubljana; EsloveniaFil: Darby, I.. Elettra-Sincrotrone Trieste SCpA di Interesse Nazionale; Italia. International Atomic Energy Agency; AustriaFil: Kaiser, R.. International Atomic Energy Agency; Austri

Sulfur homogeneity mapping in 2D and 3D can improve packaging paper strength

Sodium sulfite is commonly used for impregnating wood chips prior to refining when producing high-yield pulps such as CTMP. The impregnation process should ideally result in evenly sulfonated lignin, i.e. similar concentrations of sulfite (SO3 ^2-) ions in all parts of each wood chip. Sulfonated lignin is known to swell the fiber wall, which is beneficial for developing higher joint strength between fibers. In reality, even sulfonation is not easy to achieve considering variations in wood chip size, density, quality, etc. Being able to trace where the sulfite ions end up in the wood or fiber structure can therefore be key to both process and product development in the future. Synchrotron measurements can provide an understanding of the sulfur distribution both inside single wood fibers and on a larger scale between wood fibers. There is little knowledge of wood fiber nanostructures in 3 dimensions, although some interesting research has been conducted recently [1]. We have compared these measurements with 2D synchrotron XRF mappings [2]. The 3D material mapping provides insight into a sub-fiber level, but the 2D mapping technique might be preferable when studying sulfur distributions due to the highly uneven sulfur content observed. We can probably learn more about the development of fiber-joint-strength and strength uniformity in products by characterizing the distribution of sulfur on the sub-fiber level. This paper discusses feasible future measurement strategies. [1] Fernando, D., et.al, Sci Rep 13, 2350 (2023). DOI: 101038/s41598-023-29113-x [2] Norlin, B., et.al, JINST 18 C01012. DOI: 10.1088/1748-0221/18/01/C01012