Search results for "RECONSTRUCTION"
showing 10 items of 784 documents
Statistical Reconstruction of Microstructures Using Entropic Descriptors
2018
We report a multiscale approach of broad applicability to stochastic reconstruction of multiphase materials, including porous ones. The approach devised uses an optimization method, such as the simulated annealing (SA) and the so-called entropic descriptors (EDs). For a binary pattern, they quantify spatial inhomogeneity or statistical complexity at discrete length-scales. The EDs extract dissimilar structural information to that given by two-point correlation functions (CFs). Within the SA, we use an appropriate cost function consisting of EDs or comprised of EDs and CFs. It was found that the stochastic reconstruction is computationally efficient when we begin with a preliminary synthetic…
Box 5: Surface Crystallography Terminology
2009
The crystalline nature of the surface differs from the bulk because atoms on the surface experience a different force field due to unterminated bonds, oxidation by adatoms etc. [1]. Free energy minimisation leads to reconstruction of the surface layer from the bulk by formation of dimers and displacement of atoms from their normal sites.
Metal artifact reduction in x-ray computed tomography: Inpainting versus missing value
2011
A comparison of algorithms for reduction of metal artifacts in x-ray cone beam computed tomography (CBCT) is presented. In the context of algebraic reconstruction techniques (ART) several inpainting algorithms in the image domain are evaluated against missing data strategies. A GPU-based iterative framework is employed for a meaningful comparison of both. Simulation results from an extended Shepp-Logan phantom and real world dental data are given.
On cone-beam computed tomography artifacts induced by titanium implants
2010
Objectives: To briefly review the mathematical background of beam-hardening artifacts in cone-beam computed tomography (CBCT)-reconstruction and to investigate geometrical properties relevant for these reconstruction errors. By means of simulated and experimental results, beam-hardening effects caused by titanium implants are evaluated. Materials and methods: The geometrical and physical properties of the acquisition process of the projections used for 3D reconstruction are investigated and their effects on the CBCT images in the presence of titanium implants are derived. Beam-hardening effects are computed for a simplified polychromatic situation (three energy subsets of 80 and 110 kV) and…
Auto calibration of a cone-beam-CT
2012
Purpose: This paper introduces a novel autocalibration method for cone-beam-CTs (CBCT) or flat-panel CTs, assuming a perfect rotation. The method is based on ellipse-fitting. Autocalibration refers to accurate recovery of the geometric alignment of a CBCT device from projection images alone, without any manual measurements. Methods: The authors use test objects containing small arbitrarily positioned radio-opaque markers. No information regarding the relative positions of the markers is used. In practice, the authors use three to eight metal ball bearings (diameter of 1 mm), e.g., positioned roughly in a vertical line such that their projection image curves on the detector preferably form l…
Conjectural reconstruction from archive drawings: methodological aspects
2018
The digital reconstruction of architectural projects starting from archive sources is a well established disciplinary application useful for the study and analysis of architecture and its relations with the historical context as well as for the representation of volumes and spaces not visible in the original documents. Given the importance recognized to these operations which inevitably involve processes of hermeneusi we propose methodological guidelines for the drafting a protocol limiting arbitrariness as much as possible. The analysis was carried out on three projects by Giuseppe Damiani Almeyda (Capua 1834 - Palermo 1911), Ernesto Basile (Palermo 1857-1932) and Salvatore Benfratello (Pa…
SU-FF-T-365: Practical Reconstruction Method for 3D CT-Based Brachytherapy with Shielded Colpostats
2006
Introduction and purpose.‐ The most extended worldwide HDR and PDR afterloading machines are from Nucletron, using the Plato Treatment Planning System (TPS) to perform the clinical dosimetry. The Fletcher‐Williamson (FW) vaginal colpostat applicators are widely used with these machines, they are made of a very dense material (densimet‐17) which allows shielding up to 50% of the dose. Almost all the TPS have incorporated the CT‐Based Brachytherapy (BT), in which the CT catheters and applicators reconstruction is based on contiguous CT transverse slices where the user points the catheter position. The problem with these applicators is the production of artefacts that makes the reconstruction …
Plastic and cosmetic surgery of the male breast
2020
The thorax has a fundamental role in the aesthetic of the male body: Congenital or acquired alterations are experienced as extremely frustrating clinical situations. Most breast surgery texts briefly mention gynecomastia, but no text comprehensively addresses the male breast and thorax, including reconstructive and cosmetic surgery and surgery in transgender patients. This gap is now thoroughly filled by Plastic and Cosmetic Surgery of the Male Breast: After introducing principles of anatomy and aesthetics for the male thorax, the first part focusses on the main congenital malformations and their treatment; the main benign acquired pathologies and their treatment (including an ample section…
Comparative morphology of the postpharyngeal gland in the Philanthinae (Hymenoptera, Crabronidae) and the evolution of an antimicrobial brood protect…
2015
Background Hymenoptera that mass-provision their offspring have evolved elaborate antimicrobial strategies to ward off fungal infestation of the highly nutritive larval food. Females of the Afro-European Philanthus triangulum and the South American Trachypus elongatus (Crabronidae, Philanthinae) embalm their prey, paralyzed bees, with a secretion from a complex postpharyngeal gland (PPG). This coating consists of mainly unsaturated hydrocarbons and reduces water accumulation on the prey’s surface, thus rendering it unfavorable for fungal growth. Here we (1) investigated whether a North American Philanthus species also employs prey embalming and (2) assessed the occurrence and morphology of …
Faces and Identities: is it possible measuring the reliability of the 3D craniofacial approximations
2015
The craniofacial approximation (CFA) is largely used in forensic identification of unknown skeletonized bodies. Despite numerous forensic reports have proved successful in identifying a cadaver, it is very hard to assess the reliability of CFA methods. The present work aims to evaluate the accuracy of CFAs through the comparison of a blind facial approximation with a simultaneous faces array test. The blind CFA was made following the Manchester’s protocol. In our test the CFA was compared with a photographic array of ten faces, included the photo of the individual whom belonged the skull. The positive recognition was evaluated by a total of 320 unfamiliar assessors. During the test a survey…