X-ray phase contrast imaging is a very promising technique which may lead to significant advancements in medical imaging. One of the impediments to the clinical implementation of the technique is the general requirement to have an x-ray source of high coherence. The radiation physics group at UCL is currently developing an x-ray phase contrast imaging technique which works with laboratory x-ray sources. Validation of the system requires extensive modelling of relatively large samples of tissue. To aid this, we have undertaken a study of when geometrical optics may be employed to model the system in order to avoid the need to perform a computationally expensive wave optics calculation. In this paper, we derive the relationship between the geometrical and wave optics model for our system imaging an infinite cylinder. From this model we are able to draw conclusions regarding the general applicability of the geometrical optics approximation.
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http://dx.doi.org/10.1364/OE.18.004103 | DOI Listing |
Comput Biol Med
January 2025
Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32610, United States; Department of Medicine, University of Florida, Gainesville, FL, 32610, United States; Department of Health Outcomes and Biomedical Informatics, University of Florida, Gainesville, FL, 32610, United States; Intelligent Clinical Care Center, University of Florida, Gainesville, FL, 32610, United States. Electronic address:
Retinal image registration is essential for monitoring eye diseases and planning treatments, yet it remains challenging due to large deformations, minimal overlap, and varying image quality. To address these challenges, we propose RetinaRegNet, a multi-stage image registration model with zero-shot generalizability across multiple retinal imaging modalities. RetinaRegNet begins by extracting image features using a pretrained latent diffusion model.
View Article and Find Full Text PDFInorg Chem
January 2025
Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024, China.
Atomically precise nanoclusters, distinguished by their unique nuclearity- and structure-dependent properties, hold great promise for applications of energy conversion and electronic transport. However, the relationship between ligands and their properties remains a mystery yet to be unrevealed. Here, the influence of ligands on the electronic structures, optical properties, excited-state dynamics, and transport behavior of ReS dimer clusters with different ligands is explored using density functional theory combined with time-domain nonadiabatic molecular dynamic simulations.
View Article and Find Full Text PDFBiomed Phys Eng Express
January 2025
Physics Department, University at Albany, 1400 Washington Ave, Albany, New York, 12222-0100, UNITED STATES.
Conventional x-ray radiography relies on attenuation differences in the object, which often results in poor contrast in soft tissues. X-ray phase imaging has the potential to produce higher contrast but can be difficult to utilize. Instead of grating-based techniques, analyzer-based imaging, also known as diffraction enhanced imaging (DEI), uses a monochromator crystal with an analyzer crystal after the object.
View Article and Find Full Text PDFACS Nano
January 2025
IBM Research Europe─Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
Highly ordered nanocrystal (NC) assemblies, namely, superlattices (SLs), have been investigated as materials for optical and optoelectronic devices due to their unique properties based on interactions among neighboring NCs. In particular, lead halide perovskite NC SLs have attracted significant attention owing to their extraordinary optical characteristics of individual NCs and collective emission processes like superfluorescence (SF). So far, the primary method for preparing perovskite NC SLs has been the drying-mediated self-assembly method, in which the colloidal NCs spontaneously assemble into SLs during solvent evaporation.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Key Laboratory of Hunan Province on Information Photonics and Freespace Optical Communications, School of Physics and Electronics Science, Hunan Institute of Science and Technology, Yueyang 414006, People's Republic of China.
Constructing van der Waals heterostructures (vdWHs) has emerged as an attractive strategy to combine and enhance the optoelectronic properties of stacked materials. Herein, by means of first-principles calculations, we investigate the geometric and electronic structures of the AlP/CsBiICl vdWH as well as its tunable band structure an external electric field. The AlP/CsBiICl vdWH is structurally and thermodynamically stable due to the low binding energy and the small energy fluctuation at room temperature.
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