1,721,102 research outputs found
Calibration-free 3D ray-tracing beam hardening correction in computed tomography
Full text linkIn this paper we introduce a calibration -free beam -hardening correction technique in computed tomography, which improves the results achieved by a state-of-the-art correction method. Two main practical points are here underlined: (1) the need to perform a beam hardening correction without previous calibration; (2) the need to consider the shape of the object in all its whole three-dimensional extent. The proposed method requires: (a) a first complete reconstruction of the object by means of a cone -beam filtered back projection algorithm; (b) a segmentation of the reconstructed volume; (c) the construction of the attenuation when varying path -length graph; (d) the interpolation of the experimental data on the graph with a convenient mathematical function; (e) the correction of the measured attenuation values; (f) to perform again the complete cone -beam reconstruction. The result is an effective beam -hardening calibration -free correction over a large variety of objects, easy to use and quite fast. The proposed method results particularly useful when both the measurement time and the control of the geometry of the system are limited, like the ones generally faced in Cultural Heritage diagnostics. Computed Tomography reconstructions for test samples and for real cases are provided to highlight the effectiveness and the advantages of the new suggested approach
From micro-tomography to macro-tomography: a survey of applications for Cultural Heritage and Industry
No full textIn the framework of research projects partially funded by INFN, at the Physics Department of the University of Bologna, X-ray detection systems for high resolution Computed Tomography were realized
New X-Ray Digital Radiography and Computed Tomography for Cultural Heritage
No full textX-ray detection systems for high resolution Digital Radiography (DR) and Computed Tomography (CT) have been developed at the Physics Department of the University of Bologna. The research target is the development of systems to be applied in cultural heritage conservation and industrial radiology.
In the field of cultural heritage, different kind of objects (ancient necklaces, paintings, bronze or wooden sculptures) have to be inspected in order to acquire significant information as the method used to assemble, the manufacturing techniques or the presence of defects. These features could be very useful, for example, for dating works of art or determining appropriate maintenance and restoration procedures. Among the advanced methods available, 3D CT can be successfully used for the investigation of ancient works of art because it preserves their integrity and provides images of inner parts, otherwise not visible.
Several high-resolution CT systems, to investigate objects of different sizes (from micro to macro), have been developed at our Department and will be presented in the seminar. Some experimetal results will be presented too as the micro CT reconstruction of Roman human tooth with carie, the cone beam CT analysis on an Egyptian cat-shaped coffin exhibiting the inner mummy, the CT of an ancient large globe (2 m of diameter) located in Palazzo Vecchio, at Florence, as well as some large painted tables of great artistic interest (i.e. a painting of Raffaello)
La tomografia applicata all'industria e ad opere d'arte di grandi dimensioni
No full textIl presente articolo, inteso come continuazione di quello pubblicato nel febbraio 2007 in 21mo Secolo dagli stessi autori, vuole evidenziare il lavoro svolto e il contributo dell'Università di Bologna e dell'INFN nella TAC tridimensionale nel campo industriale e in quello per le opere d'arte di rilevante dimensione
La tomografia tridimensionale a supporto della conservazione e valorizzazione dei nostri Beni Culturali
No full textCome già avviene nel campo medico, anche per i Beni Culturali analisi diagnostiche sofisticate sono sempre più richieste da scienziati, restauratori, studiosi di storia dell'arte e, recentemente, dalla Polizia scientifica per scoprire falsi o verificare l'autenticità di reperti antichi
La tomografia tridimensionale a supporto della conservazione e valorizzazione dei nostri Beni Culturali
No full textCome già avviene nel campo medico, anche per i Beni Culturali analisi diagnostiche sofisticate sono sempre più richieste da scienziati, restauratori, studiosi di storia dell'arte e, recentemente, dalla Polizia scientifica per scoprire falsi o verificare l'autenticità di reperti antichi
The ultimate database to (re)set the evolutionary history of primate genital bones
Full text linkScientific literature concerning genital bones in primates consists of both ancient works (dating back to the nineteenth century) and more recent revisions/meta-analyses, which, however, are not always so detailed or exhaustive. Based on a thorough analysis, several conflicting data, inaccurate references, and questionable claims have emerged. We generated a binary matrix of genital bone occurrence data, considering only data at the species level, based on (1) a rigorous literature search protocol, (2) raw data (collected exclusively from primary literature), (3) an updated taxonomy (often tracing back to the species taxonomic history) and (4) new occurrence data from scanned genitals of fresh and museum specimens (using micro-computed tomography-micro-CT). Thanks to this methodological approach, we almost doubled available occurrence data so far, avoiding any arbitrary extension of generic data to conspecific species. This practice, in fact, has been recently responsible for an overestimation of the occurrence data, definitively flattening the interspecific variability. We performed the ancestral state reconstruction analysis of genital bone occurrence and results were mapped onto the most updated phylogeny of primates. As for baculum, we definitively demonstrated its simplesiomorphy for the entire order. As for baubellum, we interpreted all scattered absences as losses, actually proposing (for the first time) a simplesiomorphic state for the clitoral bone as well. The occurrence data obtained, while indirectly confirming the baculum/baubellum homology (i.e., for each baubellum a baculum was invariably present), could also directly demonstrate an intra-specific variability affecting ossa genitalia occurrence. With our results, we established a radically improved and updated database about the occurrence of genital bones in primates, available for further comparative analyses
METODO PER L’ESECUZIONE SU CALCOLATORE PARALLELO DEL MODULO DI VISUALIZZAZIONE INTERATTIVA DI UN DISPOSITIVO DI IMAGING
No full textLa presente invenzione riguarda un metodo di
calcolo parallelo e grafico su cluster, in particolare
con ambiente di sviluppo Windows HPC. È stata trovata
una metodologia per produrre un software che si basa
sulle librerie parallele (MPI), in particolare ma non
solo in ambiente Windows HPC, e che gira su cluster in
maniera parallela ma con la visualizzazione di
un’interfaccia grafica (menu per apertura/chiusura file
e sequenze di immagini, elaborazioni e visualizzazioni
grafiche, pulsanti e bottoni per l’interfaccia utente).
Il programma viene lanciato in parallelo ma attende poi
istruzioni dall’utente. È in grado di auto-adattarsi al
numero di rank e nodi a disposizione ed è in grado di
utilizzarli quando servono per il calcolo, di metterli
in attesa quando non sono necessari e di monitorarne
l’andamento quando sono in esecuzione. Il software
sviluppato con questa metodologia è quindi in grado di
effettuare la ricostruzione ad esempio di immagini
tomografiche in parallelo e di mostrare i risultati
grafici a video. Il metodo può essere applicato a
qualsiasi software di elaborazione delle immagini di
qualsiasi tipo (imaging medico, prove non distruttive
per l’industria e i beni culturali)
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