In terms of the Science of Theological Statement Kalam Abd Allah Baydawi (d. 1316?) concisely outlines perceived Islamic reality - in its modes of the naturally Possible, the apodictically Divine, ...and the humanly heroic Prophetic - as the process of perfecting man's spiritual structure. The print edition is available as a set of two volumes (9789004121027).
The advent of immune checkpoint inhibitors (ICIs) in the field of oncology has improved the outcome response rate for a variety of neoplastic pathologies with improved cellular specificity that lacks ...the traditional adverse effects associated with chemotherapy. However, ICIs are not without adverse associations, and a growing concern for modern clinicians is the balancing of interests that most occur to minimize these adverse effects while also improving patients' conditions from an oncologic perspective. This case presents a 69-year-old man who developed multiple episodes of significant pericardial effusion while receiving infusions of pembrolizumab for stage III-A adenocarcinoma for which he underwent a pericardiostomy procedure. Given the positive response of this immunotherapy on disease progression, the decision was made to continue the administration of pembrolizumab following the pericardiostomy with the plan of using serial echocardiography studies to monitor for the presence of clinically significant pericardial effusion in the future. In this way, the patient will still be able to receive optimal treatment for his advanced cancer while preserving adequate cardiac function.
The ill-posed problem of phase retrieval in optics, using one or more intensity measurements, has a multitude of applications using electromagnetic or matter waves. Many phase retrieval algorithms ...are computed on pixel arrays using discrete Fourier transforms due to their high computational efficiency. However, the mathematics underpinning these algorithms is typically formulated using continuous mathematics, which can result in a loss of spatial resolution in the reconstructed images. Herein we investigate how phase retrieval algorithms for propagation-based phase-contrast X-ray imaging can be rederived using discrete mathematics and result in more precise retrieval for single- and multi-material objects and for spectral image decomposition. We validate this theory through experimental measurements of spatial resolution using computed tomography (CT) reconstructions of plastic phantoms and biological tissues, using detectors with a range of imaging system point spread functions (PSFs). We demonstrate that if the PSF substantially suppresses high spatial frequencies, the potential improvement from utilising the discrete derivation is limited. However, with detectors characterised by a single pixel PSF (e.g. direct, photon-counting X-ray detectors), a significant improvement in spatial resolution can be obtained, demonstrated here at up to 17%.
Material decomposition in X-ray imaging uses the energy-dependence of attenuation to digitally decompose an object into specific constituent materials, generally at the cost of enhanced image noise. ...Propagation-based X-ray phase-contrast imaging is a developing technique that can be used to reduce image noise, in particular from weakly attenuating objects. In this paper, we combine spectral phase-contrast imaging with material decomposition to both better visualize weakly attenuating features and separate them from overlying objects in radiography. We derive an algorithm that performs both tasks simultaneously and verify it against numerical simulations and experimental measurements of ideal two-component samples composed of pure aluminum and poly(methyl methacrylate). Additionally, we showcase first imaging results of a rabbit kitten's lung. The attenuation signal of a thorax, in particular, is dominated by the strongly attenuating bones of the ribcage. Combined with the weak soft tissue signal, this makes it difficult to visualize the fine anatomical structures across the whole lung. In all cases, clean material decomposition was achieved, without residual phase-contrast effects, from which we generate an un-obstructed image of the lung, free of bones. Spectral propagation-based phase-contrast imaging has the potential to be a valuable tool, not only in future lung research, but also in other systems for which phase-contrast imaging in combination with material decomposition proves to be advantageous.
Multienergy X‐ray detection is critical to effectively differentiate materials in a variety of diagnostic radiology and nondestructive testing applications. Silicon and selenium X‐ray detectors are ...the most common for multienergy detection; however, these present poor energy discrimination across the broad X‐ray spectrum and exhibit limited spatial resolution due to the high thicknesses required for radiation attenuation. Here, an X‐ray detector based on solution‐processed thin‐film metal halide perovskite that overcomes these challenges is introduced. By harnessing an optimized n‐i‐p diode configuration, operation is achieved across a broad range of soft and hard X‐ray energies stemming from 0.1 to 10's of keV. Through detailed experimental and simulation work, it is shown that optimized Cs0.1FA0.9PbI3 perovskites effectively attenuate soft and hard X‐rays, while also possessing excellent electrical properties to result in X‐ray detectors with high sensitivity factors that exceed 5 × 103 µC GyVac−1 cm−2$\mu {\rm{C}}\;{{\bf Gy}}_{{\rm{Vac}}}^{ - 1}\;{\rm{c}}{{\rm{m}}^{ - 2}}$ and 6 × 104 µC Gy−1 cm−2 within soft and hard X‐ray regimes, respectively. Harnessing the solution‐processable nature of the perovskites, roll‐to‐roll printable X‐ray detectors on flexible substrates are also demonstrated.
Both soft and hard X‐ray regimes provide important spectroscopic prospects toward understanding complex heterogenous objects. Here, it is showcased that Cs0.1FA0.9PbI3 perovskites within an n‐i‐p configuration can effectively absorb X‐rays across both regimes due to their high attenuation coefficients. It is anticipated that these printable, scalable, and flexible devices can provide a step‐jump for imaging applications requiring broad‐spectrum multienergy X‐ray detection.
Full Field X-Ray Scatter Tomography Ruben, Gary; Pinar, Isaac; Brown, Jeremy M. C. ...
IEEE transactions on medical imaging,
08/2022, Volume:
41, Issue:
8
Journal Article
Open access
In X-ray imaging, photons are transmitted through and absorbed by the target object, but are also scattered in significant quantities. Previous attempts to use scattered X-ray photons for imaging ...applications used pencil or fan beam illumination. Here we present 3D X-ray Scatter Tomography using full-field illumination for small-animal imaging. Synchrotron imaging experiments were performed on a phantom and the chest of a juvenile rat. Transmitted and scattered photons were simultaneously imaged with separate cameras; a scientific camera directly downstream of the sample stage, and a pixelated detector with a pinhole imaging system placed at <inline-formula> <tex-math notation="LaTeX">45{}^\circ </tex-math></inline-formula> to the beam axis. We obtained scatter tomogram feature fidelity sufficient for segmentation of the lungs and major airways in the rat. The image contrast in the scatter tomogram slices approached that of transmission imaging, indicating robustness to the amount of multiple scattering present in our case. This opens the possibility of augmenting full-field 2D imaging systems with additional scatter detectors to obtain complementary modes or to improve the fidelity of existing images without additional dose, potentially leading to single-shot or reduced-angle tomography or overall dose reduction for live animal studies.
A powerful strategy to obtain complex supramolecular materials is the bottom-up construction of noncovalently bound materials by hierarchical self-assembly. This assembly process involves stepwise, ...uniform increases to the architectural complexity of a substrate, starting from discrete precursors and growing in dimensionality through controlled reactivity to a final product. Herein, two orthogonal processes are exploited: coordination-driven self-assembly and hydrogen bonding. The former relies on the predictable formation of metal–ligand bonds wherein the directionalities of the rigid precursors used determines the structural outcome. The latter uses 2-ureido-4-pyrimidinone interfaces that are structurally robust by virtue of the quadruple hydrogen bonding that can occur between subunits. By combining these two processes into a single system, it is possible to generate hierarchical materials that preserve the attractive tunability associated with discrete supramolecular coordination complexes. For instance, the synthesis of a one-dimensional chain comprising linked metalla-rhomboids is readily adapted to a 2D cross-linked hexagonal network by simply selecting a different metal acceptor precursor as an assembly component. The specific interactions between subunits, in this case platinum(II)-pyridyl bonds and the quadruple H-bonding of ureidopyrimidinone, are unchanged, establishing a unique strategy to obtain supramolecular polymers with marked topological differences with minimal synthetic redesign. In addition, the structural rigidity imposed by the inclusion of the platinum metallacycles serves to minimize the formation of cyclic oligomers, increasing the efficacy of formation and improving the properties of the resultant materials. Furthermore, this study taps the potential of organoplatinum(II) metallacycles in materials science.
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