The role of the GI radiographer: A UK perspective

Context: Since the 1990s radiographers in the United Kingdom have expanded their role in gastrointestinal (GI) radiology, first by performing double-contrast barium enema (DCBE) examinations independently and later by interpreting and reporting the results of these exams. Objective: This article will trace the evolution of GI radiographers in the United Kingdom, evaluate their success and explore how the U.K. experience could apply to American radiologist assistants. Methods: The authors surveyed the professional literature to determine the historical context in which GI radiographers emerged and assess how their performance on DCBE exams compares with radiologists’ performance. Results: DCBE exams performed by GI radiographers have been shown to be efficient, cost effective and safe. In addition, GI radiographers have helped reduce waiting and turnaround times for DCBE exams. Summary: The success of GI radiographers in the United Kingdom offers assurance that radiologist assistants can benefit American patients, radiologists and radiologic technologists

Single-Step Quantum Search Using Problem Structure

The structure of satisfiability problems is used to improve search algorithms for quantum computers and reduce their required coherence times by using only a single coherent evaluation of problem properties. The structure of random k-SAT allows determining the asymptotic average behavior of these algorithms, showing they improve on quantum algorithms, such as amplitude amplification, that ignore detailed problem structure but remain exponential for hard problem instances. Compared to good classical methods, the algorithm performs better, on average, for weakly and highly constrained problems but worse for hard cases. The analytic techniques introduced here also apply to other quantum algorithms, supplementing the limited evaluation possible with classical simulations and showing how quantum computing can use ensemble properties of NP search problems.Comment: 39 pages, 12 figures. Revision describes further improvement with multiple steps (section 7). See also http://www.parc.xerox.com/dynamics/www/quantum.htm

Double crystal x-ray diffraction simulations of diffusion in semiconductor microstructures

Diffusion in group IV, III-V and II-VI semiconductors is an interesting problem not only from a fundamental physics viewpoint but also in practical terms, since it could determine the useful lifetime of a device. Any attempt to control the amount of diffusion in a semiconductor device, whether it be a quantum well structure or not, requires an accurate determination of the diffusion coefficient. The present theoretical study shows that this could be achieved via x-ray diffraction studies in quantum well structures. It is demonstrated that the rocking curves of single quantum wells are not sensitive to diffusion. However the intensity of the first order satellite, which is characteristic of superlattice rocking curves, is strongly dependent upon diffusion and it is proposed that this technique could be used to measure the diffusion coefficient D. © 1998 American Institute of Physics

Challenges associated with x-ray imaging of stretcher-bound patients

Patients often arrive at imaging departments on stretchers, and in certain circumstances they must remain on the stretcher for the imaging examination to reduce the likelihood of exacerbating injuries. Imaging stretcher-bound patients can be challenging, with many physical and technical variables to consider. These challenges occur because of differences between imaging a patient on a tabletop and imaging a patient on a stretcher. This article reviews the issues associated with imaging stretcher- bound patients, including the unavailability of the automatic exposure control, different grids used, geometric factors, and variability in stretcher design

External Shear in Quadruply Imaged Lens Systems

We use publicly available N-body simulations and semi-analytic models of galaxy formation to estimate the levels of external shear due to structure near the lens in gravitational lens systems. We also describe two selection effects, specific to four-image systems, that enhance the probability of observing systems to have higher external shear. Ignoring additional contributions from "cosmic shear" and assuming that lens galaxies are not significantly flattened, we find that the mean shear at the position of a quadruple lens galaxy is 0.11, the rms shear is roughly 0.15, and there is roughly a 45% likelihood of external shear greater than 0.1. This is much larger than previous estimates and in good agreement with typical measured external shear. The higher shear primarily stems from the tendency of early-type galaxies, which are the majority of lenses, to reside in overdense regions.Comment: 5 pages, 2 figures, ApJ in press, minor revision

Does collimation affect patient dose in antero-posterior thoraco-lumbar spine?

BACKGROUND: The purpose of this study is to determine the effect of collimation on the lifetime attributable risk (LAR) of cancer incidence in all body organs (effective risk) in patients undergoing antero-posterior (AP) examinations of the spine. This is of particular importance for patients suffering from scoliosis as in their case regular repeat examinations are required and also because such patients are usually young and more susceptible to the effects of ionising radiation than are older patients. METHOD: High sensitivity thermo-luminescent dosimeters (TLDs) were used to measure radiation dose to all organs of an adult male dosimetry phantom, positioned for an AP projection of the thoraco-lumbar spine. Exposures were made, first applying tight collimation and then subsequently with loose collimation, using the same acquisition factors. In each case, the individual TLDs were measured to determine the local absorbed dose and those representing each organ averaged to calculate organ dose. This information was then used to calculate the effective risk of cancer incidence for each decade of life from 20 to 80, and to compare the likelihood of cancer incidence when using tight and loose collimation. RESULTS: The calculated figures for effective risk of cancer incidence suggest that the risk when using loose collimation compared to the use of tight collimation is over three times as high and this is the case across all age decades from 20 to 80. CONCLUSION: Tight collimation can greatly reduce radiation dose and risk of cancer incidence. However collimation in scoliotic patients can be necessarily limited

New analysis in the field of open cluster Collinder 223

The present study of the open cluster Collinder 223 (Cr 223) has been mainly depended on the photoelectric data of Claria & Lapasset (1991; hereafter CL91). This data of CL91 has been used with the cluster's image of AAO-DSS in order to re-investigate and improve the main parameters of Cr 223. Stellar count has been achieved to determine the stellar density, the cluster's center and the cluster's diameter. In addition, the luminosity function, mass function, and the total mass of the cluster have been estimated.Comment: 12 pages, 8 figure

Microbiological profile of salpicão de vinhais and chouriça de vinhais from raw materials to final products: Traditional dry sausages produced in the North of Portugal

Salpicão de Vinhais and Chouriça de Vinhais are traditional dry-fermented meat sausages produced in the North of Portugal. The microbiological profile during production of both products was followed in three small processing units. Lactic acid bacteria were the most prevalent microorganisms, with enhanced growth during the smoking process and a consequent decrease of pH. This study demonstrated that when highly contaminated raw ingredients are used, pathogens might not be eliminated during processing (from seasoning until the end of smoking). Therefore, it is important to highlight that to produce safe Salpicão and Chouriça following traditional recipes and methodologies it is necessary to work under hygienic conditions using raw materials of good microbiological quality. Industrial relevance: Preservation of pork meat in the form of semi-dry, fermented and smoked products having a long shelf-life, is an age-old artisanal process that is still practiced in many areas of the world. In many rural communities production has a significant impact on the local economy and food supply, but these products are now becoming increasingly popular in urban areas. In a more widespread distribution of such artisanal products, it is important that consumers are not exposed to undue risks of food-borne infections or intoxications. This study investigates the evolution of the microflora and microbiological safety during the production processes of two such traditional products in the North of Portugal, and during storage of the final products.info:eu-repo/semantics/acceptedVersio

Adiabatic Quantum Computing for Random Satisfiability Problems

The discrete formulation of adiabatic quantum computing is compared with other search methods, classical and quantum, for random satisfiability (SAT) problems. With the number of steps growing only as the cube of the number of variables, the adiabatic method gives solution probabilities close to 1 for problem sizes feasible to evaluate via simulation on current computers. However, for these sizes the minimum energy gaps of most instances are fairly large, so the good performance scaling seen for small problems may not reflect asymptotic behavior where costs are dominated by tiny gaps. Moreover, the resulting search costs are much higher than for other methods. Variants of the quantum algorithm that do not match the adiabatic limit give lower costs, on average, and slower growth than the conventional GSAT heuristic method.Comment: added discussion of discrete adiabatic method, and simulations with 30 bits 8 pages, 8 figure

A review of mammographic positioning image quality criteria for the craniocaudal projection

Detection of breast cancer is reliant on optimal breast positioning and the production of quality images. Two projections, the mediolateral (MLO) and craniocaudal (CC), are routinely performed. Determination of successful positioning and inclusion of all breast tissue is achieved through meeting stated image quality criteria. For the CC view, current image quality criteria are inconsistent. Absence of reliable anatomical markers, other than the nipple, further contribute to difficulties in assessing the quality of CC views. The aim of this paper was to explore published international quality standards to identify and find the origin of any CC positioning criteria which might provide for quantitative assessment. The pectoralis major (pectoral) muscle was identified as a key posterior anatomical structure to establish optimum breast tissue inclusion on mammographic projections. It forms the first two of the three main CC metrics that are frequently reported 1. visualisation of the pectoral muscle, 2. measurement of the posterior nipple line (PNL) and 3. depiction of retroglandular fat. This literature review explores the origin of the three metrics, and discusses three key publications, spanning 1992 to 1994, on which subsequent image quality standards have been based. The evidence base to support published CC metrics is sometimes not specified and more often the same set of publications are cited, most often without critical evaluation. To conclude, there remains uncertainty if the metrics explored for the CC view support objective evaluation and reproducibility to confirm optimal breast positioning and quality images