Search results for "tomography"

Integrated archaeological and geophysical survey for searching the roman temple of Augustus in Terragona, Spain

2009

The summit part of Mount Etna revealed by High Resolution DC Electrical Resistivity Tomography coupled with complementary geophysical and soil gas te…

2016

Between 25 June and 13 July 2015 a very deep ERT profile (Pole-Dipole configuration, 40m spacingbetween electrodes and a remote electrode located at ~10km from the acquisition points) has been performedin the framework of the “MED-SUV” Project. Self-potential, soil gas concentrations (CO2, 222Rn, 220Rn, He,H2 and CH4) and soil temperature measurements were coupled to the ERT profile with a spacing of 20m(except for Rn: 40m). The NE-SW profile crossed Etnas summit craters in the middle of the 5720m ERTtotal length. Six roll along protocols of . of the dispositive (600m out of 2520m tot) have been carried outand, for the first time, a high resolution DC ERT profile reached the noticeable inve…

A constrained geophysical model of the landslide that affects the Agrigento Cathedral

2012

The MYG methodology to carry out 3D electrical resistivity tomography on media covered by vulnerable surfaces of artistic value

2010

Electrical Resistivity Tomography (ERT) is not yet frequently used in the study of walls, floors and foundations of buildings of artistic value, like Ground Penetrating Radar (GPR) or other commoner techniques, although it exhibits a great potentiality in terms of resolution power. The main limitation for the applicability of ERT to the Cultural Heritage field arises from the method of current injection: it is often necessary to drive current electrodes into small perforations on the acquisition surface in order to get a current flow sufficient to obtain a good signal-to-noise ratio. To overcome this limitation the Maximum-Yield Grid (MYG) methodology has been developed, in which only a small fr…

Statistical approach for cavity detection using seismic refraction and electrical resistivity data

2017

To test limitations and effectiveness of seismic tomography when coupled to geoelectrical technique for cavity detection 2D synthetic models were used. Synthetic models were created with different number of cavity and blocks of highly cohesive lithological material (high seismic velocity and resistivity values). A modified version of multiple gradient (Martorana et al., 2016) has been used for electrical sequence. The cluster analysis performed on static units defined by electrical resistivity values, P wave velocities, and seismic density on coincident sections, allowed to interpret subsoil structures. The use of the non-hierarchical clustering algorithm has been chosen because it is less …

Resolution in wave-field tomographic approach

2011

A memetic approach to discrete tomography from noisy projections

2010

Discrete tomography deals with the reconstruction of images from very few projections, which is, in the general case, an NP-hard problem. This paper describes a new memetic reconstruction algorithm. It generates a set of initial images by network flows, related to two of the input projections, and lets them evolve towards a possible solution, by using crossover and mutation. Switch and compactness operators improve the quality of the reconstructed images during each generation, while the selection of the best images addresses the evolution to an optimal result. One of the most important issues in discrete tomography is known as the stability problem and it is tackled here, in the case of no…

A Network Tomography Approach for Traffic Monitoring in Smart Cities

2018

Traffic monitoring is a key enabler for several planning and management activities of a Smart City. However, traditional techniques are often not cost efficient, flexible, and scalable. This paper proposes an approach to traffic monitoring that does not rely on probe vehicles, nor requires vehicle localization through GPS. Conversely, it exploits just a limited number of cameras placed at road intersections to measure car end-to-end traveling times. We model the problem within the theoretical framework of network tomography, in order to infer the traveling times of all individual road segments in the road network. We specifically deal with the potential presence of noisy measurements, and t…

Metabolic impact of Partial Volume Correction of [18F]FDG PET-CT oncological studies on the assessment of tumor response to treatment

2014

AIM: The aim of this work is to evaluate the metabolic impact of Partial Volume Correction (PVC) on the measurement of the Standard Uptake Value (SUV) from [18F]FDG PET-CT oncological studies for treatment monitoring purpose. METHODS: Twenty-nine breast cancer patients with bone lesions (42 lesions in total) underwent [18F]FDG PET-CT studies after surgical resection of breast cancer primitives, and before (PET-I) and after (PET-II) chemotherapy and hormone treatment. PVC of bone lesion uptake was performed on the two [18F]FDG PET-CT studies, using a method based on Recovery Coefficients (RC) and on an automatic measurement of lesion metabolic volume. Body-weight average SUV was calculated f…

A Graph-Based Method for PET Image Segmentation in Radiotherapy Planning: A Pilot Study

2013

Target volume delineation of Positron Emission Tomography (PET) images in radiation treatment planning is challenging because of the low spatial resolution and high noise level in PET data. The aim of this work is the devel- opment of an accurate and fast method for semi-automatic segmentation of me- tabolic regions on PET images. For this purpose, an algorithm for the biological tumor volume delineation based on random walks on graphs has been used. Va- lidation was first performed on phantoms containing spheres and irregular in- serts of different and known volumes, then tumors from a patient with head and neck cancer were segmented to discuss the clinical applicability of this algo- rith…