2,246 research outputs found
3D MODELLING AND RAPID PROTOTYPING FOR CARDIOVASCULAR SURGICAL PLANNING – TWO CASE STUDIES
No full textIn the last years, cardiovascular diagnosis, surgical planning and intervention have taken advantages from 3D modelling and rapid
prototyping techniques. The starting data for the whole process is represented by medical imagery, in particular, but not exclusively,
computed tomography (CT) or multi-slice CT (MCT) and magnetic resonance imaging (MRI). On the medical imagery, regions of
interest, i.e. heart chambers, valves, aorta, coronary vessels, etc., are segmented and converted into 3D models, which can be finally
converted in physical replicas through 3D printing procedure. In this work, an overview on modern approaches for automatic and semiautomatic
segmentation of medical imagery for 3D surface model generation is provided. The issue of accuracy check of surface
models is also addressed, together with the critical aspects of converting digital models into physical replicas through 3D printing
techniques. A patient-specific 3D modelling and printing procedure (Figure 1), for surgical planning in case of complex heart diseases
was developed. The procedure was applied to two case studies, for which MCT scans of the chest are available. In the article, a detailed
description on the implemented patient-specific modelling procedure is provided, along with a general discussion on the potentiality
and future developments of personalized 3D modelling and printing for surgical planning and surgeons practice
Patient-specific 3D modelling of heart and cardiac structures workflow: an overview of methodologies
No full textCardiovascular diagnosis, surgical planning and intervention are among the most interested in recent developments in the field of 3D acquisition, modelling and rapid prototyping techniques. In case of complex heart disease, to provide an accurate planning of the intervention and to support surgical planning and intervention, an increasing number of Hospitals make use of physical 3D models of the cardiac structure, including heart, obtained using additive manufacturing starting from the 3D model retrieved with medical imagery. The present work aims in providing an overview on most recent approaches and methodologies for creating physical prototypes of patient-specific heart and cardiac structures, with particular reference to most critical phases such as segmentation and aspects concerning converting digital models into physical replicas through rapid prototyping techniques. First, recent techniques for image enhancement to highlight anatomical structures of interest are presented together with the current state of the art of semi-automatic image segmentation. Then, most suitable techniques for prototyping the retrieved 3D model are investigated so as to draft some hints for creating prototypes useful for planning the medical intervention
“CAD design and development of a sensorized liner for in-vivo detection of pressures at the interface between socket and residual limb in transtibial amputees”
No full textreservedIl presente lavoro di tesi si inserisce in un progetto di ricerca collaborativo tra l'Università di Padova, rappresentata dal laboratorio del Professor Nicola Petrone e dalla Professoressa Francesca Uccheddu, e le aziende "Orthomedica" e "Protolab".
L'obiettivo principale di questa ricerca è sviluppare un approccio innovativo per la progettazione e la realizzazione di protesi trans-tibiali, attraverso la creazione di un liner sensorizzato, evidenziando il potenziale delle tecnologie moderne nel migliorare la qualità di vita dei pazienti amputati, favorendo l'adozione di soluzioni più precise e su misura.
La tesi ha come oggetto principe il liner, il quale viene ottenuto mediante un processo di colata di silicone all’interno di uno stampo progettato con modellazione CAD, realizzato come parte del progetto. Lo stampo, oltre a servire per la realizzazione del liner, è anche utilizzato per creare un calco del moncone del paziente, che consente di condurre test in vitro al fine di verificare la distribuzione delle pressioni e ottimizzare il comfort del dispositivo.
Oltre alla modellazione CAD, i sensori di pressione forniti dall'azienda "Protolab" vengono integrati nel liner durante la fase di produzione. Questi sensori permettono di monitorare e analizzare la distribuzione delle pressioni all’interno della protesi, offrendo dati utili per ottimizzare il comfort e le prestazioni del dispositivo. Il processo culmina con la realizzazione dei socket tramite stampa 3D, utilizzando le tecnologie avanzate disponibili presso l'azienda "Orthomedica".
Inoltre, oltre ai test in vitro, la protesi sarà sottoposta anche a test in vivo, permettendo di valutare la risposta del paziente al dispositivo in condizioni reali
Computer Aided Design Tool for GT Ventilation System Ductworks
No full textThe proper design of a ventilation system (VS) is an important requirement in the Gas Turbine (GT) and energy production industry in general. In fact, ventilation systems are designed to provide a continuous source of cooling air so as to: remove heat and maintain the air temperature in the compartment below the operating limit; prevent the accumulation of hazardous gases; preserve a constant and uniform airflow through the ducts, independently from the environmental conditions; avoid accidental dust and sand contamination in gas turbines, especially when these are located in regions prone to sandstorm conditions. When compared to typical Heating, Ventilating and Air Conditioning (HVAC) systems, the design of VSs results particularly challenging since many requirements, generally involving different engineering aspects such as fluid-dynamic, acoustic and structural, have to be fulfilled. Generally speaking, a VS is composed by a number of elements such as linear ducts, expansion joints, transition duct sections, elbows, outlets to the atmosphere, supports, saddles and brackets. Shape and dimensions of these elements may significantly vary depending on the kind of application. Basically, the elements may have circular/oval or rectangular/square section. In the first case, they are manufactured by employing calendaring process followed by welding. Otherwise, the component is realized by cutting and welding metal sheets. Elements are coupled by using bolted flanges or welded joints in order to obtain the entire VS ductwork
Comparing two 3D measurement techniques for documenting painted wooden panels surface deformations on a real test case: "mystical Marriage of Saint Catherine" by Renaissance artist Piero di Cosimo
No full textAncient wooden panel paintings are an essential part of our cultural heritage. Wood as artworks support has always been very popular and painted panels are largely diffuse in many churches and museums. However, depending on conservation conditions, the wooden panels shape may vary and if not properly controlled may lead to some sever damage to the artworks. This paper presents the results of a study on the measurement of paintings surface deformation carried out using two different three-dimensional acquisition devices both making use of structured light. The main goal was to highlight and measure the reliability of such 3D measuring techniques to evaluate deviations from planarity due to the curving and warping of the wood and to document spatial deformation suffered by the painting and monitoring its conservation status
Improvements on a MMI based method for automatic texture mapping of 3D dense models
No full textMaximization of Mutual Information routines proved to be suitable for registration of multimodal images. Here a method is proposed to select, in a set of candidates, the image which has a closer resemblance with a given external one. Such algorithm is intended to serve within a wider scope procedure for the automatic texturing of 3D models, where the initial 2D-3D registration problem is shifted to a 2D-2D registration challenge. In order to improve its performance a number of variations in the way the Mutual Information is computed are introduced and a method to judge its reliability is proposed
Automatic graves' orientation detection: A tool for spatial archeology
No full textThe assessment of the preferred orientation of graves in a necropolis represents an interesting contribution to the study of a civilization. In this paper two different methods are presented. The first one implies a parameterization of the map, i.e. its manual translation into a shapefile, where each grave of the necropolis is separately analyzed and a subsequent automatic orientation of the whole necropolis is achieved. This method proved to be highly reliable in the determining the tomb orientation and entrance direction, although it was quite time consuming, since a fairly important amount of manual work was required. On the other hand, the alternative proposed method using the Radon transform proved to be able to assess the main direction of the whole necropolis analyzing the scanned map image, in a fast and reliable way, without the need of any manual intervention. However in the simplest implementation and for the entire image at once, with the Radon transform it is not possible to determine the versus of the located lines. This is instead achievable when analyzing the single graves. In both cases, the main orientation was correctly detecte
Identification of pictorial materials by means of optimized multispectral reflectance image processing
No full textImage spectroscopy may allow identifying the materials present on a painting surface in a non-invasive way. The proposed method aims at optimizing, and thus reducing, the number of filters employed, while still providing a robust method, that achieves similar performances as traditional ones, which in turn employ a large number of filters. Moreover, we targeted the identification of the pigments present on the outer layer of a painting independently from their thickness, the underlying background or support, the binder employed, their aging and acquisition set-up. In order to achieve this objective, a relevant number of swatches have been prepared, on different supports and with different thicknesses and binding mediums. Spectral reflectance curves of such chemically known pictorial layers have been recorded by means of a spectrometer and a spectrophotometer. A novel Principal Component Analysis (PCA) based approach has been devised to select the most relevant wavebands, i.e. those that allow the most effective discrimination among (quasi)metameric colours, which are thus not to be distinguished with the naked eye or with an RGB camera. Comparisons of results using the 13 filters available on the filter wheel and of a selection of only 3 and 4 filters, support the idea of the simplified version investigated in this paper being a viable alternativ
Comparison of Mesh Simplification tools in a 3D Watermarking framework
No full textGiven a to-be-watermarked 3D model, a transformed domain analy-sis is needed to guarantee a robust embedding without compromising the visual quality of the result. A multiresolution remeshing of the model allows to repre-sent the 3D surface in a transformed domain suitable for embedding a robust and imperceptible watermark signal. Simplification of polygonal meshes is the basic step for a multiresolution remeshing of a 3D model; this step is needed to obtain the model approximation (coarse version) from which a refinement framework (i.e. 3D wavelet analysis, spectral analysis, ...) able to represent the model at multiple resolution levels, can be performed. The simplification algo-rithm should satisfy some requirements to be used in a watermarking system: the repeatability of the simplification, and the robustness of it to noise or, more generally, to slight modifications of the full resolution mesh. The performance of a number of software packages for mesh simplification, including both commercial and academic offerings, are compared in this survey. We defined a benchmark for testing the different software in the watermarking scenario and reported a comprehensive analysis of the software performances based on the geometric distortions measurement of the simplified versions
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