نتایج جستجو برای: spiral computed tomography
تعداد نتایج: 284108 فیلتر نتایج به سال:
The poor prognosis of lung cancer has barely changed in the last decades, but the prognosis is better when the disease is detected earlier. Lung cancer screening by chest radiography did not lead to a decrease in lung cancer mortality, presumably because the chest radiograph is a poor screening tool with low sensitivity. With the advent of the low-dose spiral computed tomography (CT) scan it ha...
Helical nanofilaments (HNFs) have attracted much interest because of their unique optical properties, but there have been many hurdles to overcome in using them for the practical applications due to their structural complexity. Here we demonstrate that the molecular configuration and layer conformation of a modulated HNF (HNFs(mod)) can be studied using a physicochemical confinement system. The...
Using suitable polychromatic superpositions of helical Mathieu and parabolic nondiffracting beams, we study for the first time, to the best of our knowledge, the higher-order helical Mathieu X waves and the traveling and stationary parabolic X waves. The mathematical and physical properties of these new kinds of localized pulses are discussed.
Results from a comprehensive analytical and numerical study of nonequilibrium dynamics in the two-dimensional complex Ginzburg-Landau equation have been presented. In particular, spiral defects have been used to characterize the domain growth law and the evolution morphology. An asymptotic analysis of the single-spiral correlation function shows a sequence of singularities-analogous to those se...
The cone-beam approach for image reconstruction attracts an increasing attention in various applications, especially medical imaging. Previously, the traditional practical cone-beam reconstruction method, the Feldkamp algorithm, was generalized into the case of spiral/helical scanning loci with equispatial cone-beam projection data. In this paper, we formulated the generalized Feldkamp algorith...
We read with interest the article by Dr Chang and colleagues 1 in CHEST (January 2013) about the management of ground-glass opacities (GGOs). Their data indicate that the strategy of longterm follow-up and selective surgery was appropriate. However, we do not entirely agree with their ideas. We offer a third choice of CT scan-guided biopsy to solve the long-standing issue. Previous studies have...
A 3π algorithm is obtained in which all the derivatives are confined to a detector array. Distance weighting of backprojection coefficients of the algorithm is studied. A numerical experiment indicates that avoiding differentiation along the source trajectory improves spatial resolution. Another numerical experiment shows that the terms depending on the non-standard distance weighting 1/|x − y(...
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