Effective modeling of high-energy laboratory-based x-ray phase contrast imaging utilizing absorption masks or gratings

Model refinements for the edge illumination x-ray phase contrast imaging method have been developed to improve simulation accuracy for high energy, polychromatic beams. High-energy x rays are desirable in imaging due to their penetrative power and, for biological samples, their lower dose deposition rate. Accurate models of such scenarios are required for designing appropriate imaging systems and to predict signal strength in complex settings such as clinical imaging or industrial quality assurance. When using optical components appropriate for high-energy x rays in a non-synchrotron setting, system performance was observed to deviate from that predicted by existing models. In this work, experimental data utilizing increasing thicknesses of a known filter material are used to illustrate the limitations of existing models and as validation for the new modeling features. Angular filtration of the cone beam was observed to be the most significant effect; however, specific features of the source and detector are also shown to affect system performance. We conclude by showing that a significantly improved agreement between experimental and simulated data is obtained with the refined model compared to previously existing ones

A first investigation of accuracy, precision and sensitivity of phase-based x-ray dark-field imaging

In the last two decades, x-ray phase contrast imaging (XPCI) has attracted attention as a potentially significant improvement over widespread and established x-ray imaging. The key is its capability to access a new physical quantity (the ‘phase shift’), which can be complementary to x-ray absorption. One additional advantage of XPCI is its sensitivity to micro structural details through the refraction induced dark-field (DF). While DF is extensively mentioned and used for several applications, predicting the capability of an XPCI system to retrieve DF quantitatively is not straightforward. In this article, we evaluate the impact of different design options and algorithms on DF retrieval for the Edge-Illumination (EI) XPCI technique. Monte Carlo simulations, supported by experimental data, are used to measure the accuracy, precision and sensitivity of DF retrieval performed with several EI systems based on conventional x-ray sources. The introduced tools are easy to implement, and general enough to assess the DF performance of systems based on alternative (i.e. non-EI) XPCI approaches

Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors

Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI’s achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

A sustainable solution for electricity generation using thermo-acoustic technology

Abstract: This work explores the use of thermo-acoustic system as alternative technology for electricity generation. This technology is proposed as a potential replacement for low-cost electrical power generation because of its simplicity and lack of moving parts. Thermo-acoustic generators providing clean electrical energy to power small appliances. The energy conversion from heat into sound wave is done within thermo-acoustic engine. The latter is coupled to a linear alternator for electricity generation. The study investigates the influence of the geometrical configuration of the device on to the whole functionality of the generator. The paper studies the technology through experimental trails performed using a simple arrangement to simulate the generator. The experiment is conducted in phases; the first phase identifies the best geometrical configuration of the thermo-acoustic engine by measuring the sound pressure level and the temperatures. The second phase consist of measuring the electricity generated using a Loudspeaker. The results obtained show the potential for this sustainable solution for electricity generation

Detector requirements for single mask edge illumination x-ray phase contrast imaging applications

Edge illumination (EI) is a non-interferometric X-ray phase contrast imaging (XPCI) method that has been successfully implemented with conventional polychromatic sources, thanks to its relaxed coherence requirements. Like other XPCI methods, EI enables the retrieval of absorption, refraction and ultra-small angle X-ray scattering (USAXS) signals. However, current retrieval algorithms require three input frames, which have so far been acquired under as many different illumination conditions, in separate exposures. These illumination conditions can be achieved by deliberately misaligning the set-up in different ways. Each one of these misaligned configurations can then be used to record frames containing a mixture of the absorption, refraction and scattering signals. However, this acquisition scheme involves lengthy exposure times, which can also introduce errors to the retrieved signals. Such errors have, so far, been mitigated by careful image acquisition and analysis. However, further reduction to image acquisition time and errors due to sample mask/sample movement can increase the advantages offered by the EI technique, and enable targeting more challenging applications. In this paper, we describe two simplified set-ups that exploit state-of-the-art detector technologies to achieve single-shot multi-modal imaging.Comment: 10 pages, 5 figures, Position Sensitive Detectors 11 conferenc

Monochromatic Propagation-Based Phase-Contrast Microscale Computed-Tomography System with a Rotating-Anode Source

We present an experimental setup for monochromatic propagation-based x-ray phase-contrast imaging based on a conventional rotating-copper-anode source, capable of an integrated flux up to 108 photons/s at 8 keV. In our study, the system is characterized in terms of spatial coherence, resolution, contrast sensitivity, and stability. Its quantitativeness is demonstrated by comparing theoretical predictions with experimental data on simple wire phantoms both in planar and computerized-tomography-scan geometries. Application to two biological samples of medical interest shows the potential for bioimaging on the millimeter scale with spatial resolution of the order of 10 \u3bcm and contrast resolution below 1%. All the scans are performed within laboratory-compatible exposure times, from 10 min to a few hours, and trade-offs between scan time and image quality are discussed

Signal of harm in morphine use in adults with acute pulmonary oedema: A rapid systematic review

Background. Heart failure affects nearly 65 million people globally, resulting in recurrent hospital admissions and substantial healthcare expenditure. The use of morphine in the management of acute pulmonary oedema remains controversial, with conflicting guidance and significant variation in practice. Synthesised evidence is needed to inform standard treatment guidelines and clinical practice. Objective. To determine whether morphine should be used in the treatment of acute pulmonary oedema (APE) in adults. Methods. A rapid review of systematic reviews of randomised controlled trials or observational studies, and then randomised controlled trials, was conducted searching three electronic databases (PubMed, Embase, Cochrane Library) and one clinical trial registry on 12 February 2022. We used a prespecified protocol following Cochrane rapid review methods and aligned to the National Standard Treatment Guidelines and Essential Medicines List methodology. We first considered relevant high-quality systematic reviews of randomised controlled trials or observational studies, then (if required) randomised controlled trials to inform time-sensitive or urgent evidence requests, clinical practice, policy, or standard treatment guidelines. Results. We identified four systematic reviews of observational studies. The two most relevant, up-to-date, and highest-quality reviews were used to inform evidence for critical outcomes. Morphine may increase in-hospital mortality (odds ratio (OR) 1.78; 95% confidence interval (CI) 1.01 - 3.13; low certainty of evidence; six observational studies, n=151 735 participants), resulting in 15 more per 1 000 hospital deaths, ranging from 0 to 40 more hospital deaths. Morphine may result in a large increase in invasive mechanical ventilation (OR 2.72; 95% CI 1.09 - 6.80; low certainty of evidence; four observational studies, n=167 847 participants), resulting in 45 more per 1 000 ventilations, ranging from 2 more to 136 more. Adverse events and hospital length of stay were not measured across reviews or trials. Conclusion. Based on the most recent, relevant and best-available quality evidence, morphine use in adults with APE may increase in-hospital and all-cause mortality and may result in a large increase in the need for invasive mechanical ventilation compared to not using morphine. Recommending against the use of morphine in pulmonary oedema may improve patient outcomes. Disinvesting in morphine for this indication may result in cost savings, noting the possible accrued benefits of fewer patients requiring invasive ventilation and management of morphine-related side-effects

An intra-COVID-19 assessment of hand hygiene facility, policy and staff compliance in two hospitals in Sierra Leone: is there a difference between regional and capital city hospitals?

Although hand hygiene (HH) is the most effective intervention to reduce the spread of infections, there are limited data on HH facilities, policy, and compliance in sub-Saharan Africa. This cross-sectional study is aimed at assessing HH using the WHO HH self-assessment framework, HH technical reference manual, and a modified infection control self-assessment tool in two hospitals in Sierra Leone. Only 10% and 9% of regional and capital city hospitals had running tap water, respectively. Veronica buckets were the resources for HH in 89% of units in the regional hospital and 92% of units in capital city hospital. Constant supply of soap and alcohol-based hand rub was available in 82% and 68%; and 74% and 79% of units in the capital city and regional hospitals, respectively. Only 10% of the units in both hospitals had hand-drying facilities and functional sinks. Overall HH compliance for the two hospitals was 18.6% and was higher in the regional (20.8%) than the capital city (17.0%) hospitals. The HH levels for the capital city and regional hospitals were 277.5 and 262.5 respectively. Despite the COVID-19 pandemic, there are still challenges with HH compliance in Sierra Leone. It is, therefore, necessary to strengthen the HH multi-modal strategy