Search results for "Image resolution"
showing 10 items of 377 documents
Chronic neural probe for simultaneous recording of single-unit, multi-unit, and local field potential activity from multiple brain sites
2017
Drug resistant focal epilepsy can be treated by resecting the epileptic focus requiring a precise focus localisation using stereoelectroencephalography (SEEG) probes. As commercial SEEG probes offer only a limited spatial resolution, probes of higher channel count and design freedom enabling the incorporation of macro and microelectrodes would help increasing spatial resolution and thus open new perspectives for investigating mechanisms underlying focal epilepsy and its treatment. This work describes a new fabrication process for SEEG probes with materials and dimensions similar to clinical probes enabling recording single neuron activity at high spatial resolution.Polyimide is used as a bi…
A fully automatic method for biological target volume segmentation of brain metastases
2016
Leksell Gamma Knife is a mini-invasive technique to obtain a complete destruction of cerebral lesions delivering a single high dose radiation beam. Positron Emission Tomography (PET) imaging is increasingly utilized for radiation treatment planning. Nevertheless, lesion volume delineation in PET datasets is challenging because of the low spatial resolution and high noise level of PET images. Nowadays, the biological target volume (BTV) is manually contoured on PET studies. This procedure is time expensive and operator-dependent. In this article, a fully automatic algorithm for the BTV delineation based on random walks (RW) on graphs is proposed. The results are compared with the outcomes of…
Volcanic CO_2 detection with a DFM/OPA-based lidar
2015
The DFM/OPA-based lidar BILLI was used to investigate the volcanic plume released by the hydrothermal vent of Pisciarelli, in the Campi Flegrei volcano. BILLI remotely measured CO2 concentrations in cross-sections of the nearvent plume using the differential absorption technique. To our knowledge, this is the first example of lidar-based measurement of volcanic CO2 . The spatial resolution was 1.5 m and the temporal resolution 20 s. © 2015 Optical Society of America.
Mapping lava flows at Etna Volcano using Google Earth Engine, open-access satellite data, and machine learning
2021
Estimating eruptive parameters is fundamental to assess the volcanic hazards posed to the community living at the edge of active volcanoes. Here, we analyzed satellite remote sensing data by using machine learning unsupervised and supervised techniques and analytical approaches, i.e., mathematical-physics and statistics formulations, to map lava flows emitted during the long sequences of short-lived, violent eruptions occurred at Etna volcano between December 2020 and March 2021. Satellite observations allowed to follow the evolution of eruptions thanks to their capability to survey large areas with frequent revisit time and accurate spatial resolution. We quantified the areal coverage of l…
UV camera measurements of fumarole field degassing (La Fossa crater, Vulcano Island)
2011
Abstract The UV camera is becoming an important new tool in the armory of volcano geochemists to derive high time resolution SO2 flux measurements. Furthermore, the high camera spatial resolution is particularly useful for exploring multiple-source SO2 gas emissions, for instance the composite fumarolic systems topping most quiescent volcanoes. Here, we report on the first SO2 flux measurements from individual fumaroles of the fumarolic field of La Fossa crater (Vulcano Island, Aeolian Island), which we performed using a UV camera in two field campaigns: in November 12, 2009 and February 4, 2010. We derived ~ 0.5 Hz SO2 flux time-series finding fluxes from individual fumaroles, ranging from…
HIGH QUALITY TEXTURE MAPPING PROCESS AIMED AT THE OPTIMIZATION OF 3D STRUCTURED LIGHT MODELS
2019
Abstract. This article presents the evaluation of a pipeline to develop a high-quality texture mapping implementation which makes it possible to carry out a semantic high-quality 3D textured model. Due to geometric errors such as camera parameters or limited image resolution or varying environmental parameters, the calculation of a surface texture from 2D images could present several color errors. And, sometimes, it needs adjustments to the RGB or lightness information on a defined part of the texture. The texture mapping procedure is composed of mesh parameterization, mesh partitioning, mesh segmentation unwraps, UV map and projection of island, UV layout optimization, mesh packing and mes…
High Performance 3D PET Reconstruction Using Spherical Basis Functions on a Polar Grid
2011
Statistical iterative methods are a widely used method of image reconstruction in emission tomography. Traditionally, the image space is modelled as a combination of cubic voxels as a matter of simplicity. After reconstruction, images are routinely filtered to reduce statistical noise at the cost of spatial resolution degradation. An alternative to produce lower noise during reconstruction is to model the image space with spherical basis functions. These basis functions overlap in space producing a significantly large number of non-zero elements in the system response matrix (SRM) to store, which additionally leads to long reconstruction times. These two problems are partly overcome by expl…
An automatic method for metabolic evaluation of gamma knife treatments
2015
Lesion volume delineation of Positron Emission Tomography images is challenging because of the low spatial resolution and high noise level. Aim of this work is the development of an operator independent segmentation method of metabolic images. For this purpose, an algorithm for the biological tumor volume delineation based on random walks on graphs has been used. Twenty-four cerebral tumors are segmented to evaluate the functional follow-up after Gamma Knife radiotherapy treatment. Experimental results show that the segmentation algorithm is accurate and has real-time performance. In addition, it can reflect metabolic changes useful to evaluate radiotherapy response in treated patients.
Requirements on resolution of digital imaging equipment in the cardiac catheterization laboratory.
1988
We evaluated the requirements on spatial resolution of digital imaging equipment in the cardiac catheterization laboratory. Fifty cinefilms of the heart as the biological object and one film of a lead-ladder-pattern as an objective test were used. The patient films were examined for the visibility of the left ventricular angiogram, coronary arterial tree, coronary artery lesions, branching of septal arteries and the number of septal arteries. All films were viewed three times: with a 625 line TV-system, with a 1249 line TV-system and with a cineprojector. It was found that two application areas with different demands on the spatial and temporal resolution can be distinguished: 1) low spatia…
Diffuse reflectance and fluorescence multispectral imaging system for assessment of skin
2014
The diffuse reflectance multispectral imaging technique has been used for distant mapping of in vivo skin chromophores (hemoglobin and melanin). The fluorescence multispectral imaging is not so common for skin applications due to complicity of data acquisition and processing, but could provide additional information about skin fluorophores. Both techniques are compatible, and could be combined into a multimodal solution. The multispectral imaging system Nuance based on liquid crystal tunable filters was adapted for diffuse reflectance and fluorescence spectral imaging of in vivo skin. Uniform illumination was achieved by LED ring light. Combination of four LEDs (warm white, 770 nm, 830 nm a…