Search results for " Three-Dimensional"
showing 10 items of 323 documents
BIFOCAL PAIRS OF IMAGES FOR LOW-COST SURVEY IN CLOSE RANGE PHOTOGRAMMETRY
2019
Abstract. This paper present a method for close range photogrammetry based on an camera positioning scheme in which two cameras capture an equal portion of an object at the same scale, but have different focal lengths and camera-to-object distances. This scheme is alternative to the stereoscopic scheme and is associated with a system of equations which permits one to calculate first the relief displacement of points on a photograph and then their relief relative to a reference plane. The obtained relief and relief displacement values can be used to produce low-cost orthophotographs by using software for image processing, which doesn’t need to be dedicated, but has to provide measurement and…
Preconcentration and speciation analysis of mercury : 3D printed metal scavenger-based solid-phase extraction followed by analysis with inductively c…
2021
A selective method for preconcentration and determination of methylmercury (MeHg) and inorganic mercury (iHg) in natural water samples at the ng L−1 level has been developed. The method involves adsorption of Hg species into a 3D printed metal scavenger and sequential elution with acidic thiourea solutions before ICP-MS determination. Experimental parameters affecting the preconcentration of MeHg and iHg such as the sample matrix, effect of the flow rate on adsorption, eluent composition, and elution mode have been studied in detail. The obtained method detection limits, considering the preconcentration factors of 42 and 93, were found to be 0.05 ng L−1 and 0.08 ng L−1 for MeHg and iHg, res…
3D reconstruction techniques made easy: know-how and pictures
2005
Three-dimensional reconstructions represent a visual-based tool for illustrating the basis of three-dimensional post-processing such as interpolation, ray-casting, segmentation, percentage classification, gradient calculation, shading and illumination. The knowledge of the optimal scanning and reconstruction parameters facilitates the use of three-dimensional reconstruction techniques in clinical practise. The aim of this article is to explain the principles of multidimensional image processing in a pictorial way and the advantages and limitations of the different possibilities of 3D visualisation.
Advanced Protocol for Three-Dimensional Transesophageal Echocardiography Guidance Implementing Real-Time Multiplanar Reconstruction for Transcatheter…
2019
Transcatheter direct annuloplasty has been introduced as a novel interventional treatment option for severe mitral valve regurgitation. Until now, only one direct annuloplasty device (Edwards Cardioband) has been commercially available, being implanted in more than 250 patients worldwide. Yet this procedure poses greater challenges regarding optimal fluoroscopic and echocardiographic guidance compared with edge-to-edge repair: correct localization and orientation of the anchors upon penetration into the fibrous mitral annulus tissue and the basal left ventricular myocardium are preconditions for an optimal result and essential to avoid damage of the neighboring structures (atrioventricular …
Diagnostic of craniofacial asymmetry : literature review
2009
Facial asymmetry is a common feature in many syndromes, and requires surgery as the only valid treatment option. Routine diagnostic methods (frontal RX, panoramic RX and submentovertex RX) have serious limitations mainly due to the transfer from a three dimensional image to a two dimensional plane. The feasibility of such methods is poorly supported due to inherent projection errors (image magnification, cranial rotation) and identification errors (image quality, precision and reproducibility). The use of computer tomographies represents a substantial improvement in the sense of skeletal and soft tissue structures? reproduction precision. The interpretation of this new data source makes evi…
Artefacts in CBCT: a review
2011
Artefacts are common in today's cone beam CT (CBCT). They are induced by discrepancies between the mathematical modelling and the actual physical imaging process. Since artefacts may interfere with the diagnostic process performed on CBCT data sets, every user should be aware of their presence. This article aims to discuss the most prominent artefacts identified in the scientific literature and review the existing knowledge on these artefacts. We also briefly review the basic three-dimensional (3D) reconstruction concept applied by today's CBCT scanners, as all artefacts are more or less directly related to it.
Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers.
2013
AB Purpose: Knee pain and Achilles tendinopathies are the most common complaints among runners. The differences in the running mechanics may play an important role in the pathogenesis of lower limb overuse injuries. However, the effect of a runner's foot strike pattern on the ankle and especially on the knee loading is poorly understood. The purpose of this study was to examine whether runners using a forefoot strike pattern exhibit a different lower limb loading profile than runners who use rearfoot strike pattern. Methods: Nineteen female athletes with a natural forefoot strike (FFS) pattern and pair-matched women with rearfoot strike (RFS) pattern (n = 19) underwent 3-D running analysis …
Automatic detection of lung nodules in CT datasets based on stable 3D mass–spring models
2012
We propose a computer-aided detection (CAD) system which can detect small-sized (from 3 mm) pulmonary nodules in spiral CT scans. A pulmonary nodule is a small lesion in the lungs, round-shaped (parenchymal nodule) or worm-shaped (juxtapleural nodule). Both kinds of lesions have a radio-density greater than lung parenchyma, thus appearing white on the images. Lung nodules might indicate a lung cancer and their early stage detection arguably improves the patient survival rate. CT is considered to be the most accurate imaging modality for nodule detection. However, the large amount of data per examination makes the full analysis difficult, leading to omission of nodules by the radiologist. We…
Patent Foramen Ovale and Thromboembolic Complications
2010
The foramen ovale, an atrial septal defect which is essential in the fetal circulation, remains patent through adulthood in approximately 25% of the general population and so it represents the most common persistent abnormality of fetal origin. Patent foramen ovale (PFO) allows interatrial right-to-left blood shunting during those periods of the cardiac cycle in which the right atrial pressure exceeds the left one. An increasing number of pathological manifestations of PFO has been recently identified; among these, paradoxical systemic embolism, refractory hypoxemia in patients with right ventricular myocardium infarction or severe pulmonary disease, orthostatic oxygen desaturation in the r…
3D virtual histopathology of cardiac tissue from Covid-19 patients based on phase-contrast X-ray tomography
2021
eLife 10, e71359 (2021). doi:10.7554/eLife.71359