227 research outputs found
An automatic system to discriminate malignant from benign massive lesions on mammograms
No full textMammography is widely recognized as the most reliable technique for early detection of breast cancers. Automated or semi-automated computerized classification schemes can be very useful in assisting radiologists with a second opinion about the visual diagnosis of breast lesions, thus leading to a reduction in the number of unnecessary biopsies. We present a computer-aided diagnosis (CADi) system for the characterization of massive lesions in mammograms, whose aim is to distinguish malignant from benign masses. The CADi system we realized is based on a three-stage algorithm: (a) a segmentation technique extracts the contours of the massive lesion from the image; (b) 16 features based on size and shape of the lesion are computed; (c) a neural classifier merges the features into an estimated likelihood of malignancy. A data set of 226 massive lesions (109 malignant and 117 benign) has been used in this study. The system performances have been evaluated in terms of the receiver-operating characteristic (ROC) analysis, obtaining A(z) = 0.80 +/- 0.04 as the estimated area under the ROC curve. (c) 2006 Elsevier B.V. All rights reserved. RI Retico, Alessandra /I-6321-201
Venetico, retico e camuno
No full textL’articolo propone un quadro delle lingue preromane dell’Italia nord-orientale, in una prospettiva che non vuole essere tanto una descrizione dello stato delle attuali conoscenze, quanto piuttosto una riflessione sulle problematiche attualmente connesse ai singoli ambiti di studio (venetico, retico, camuno), di fatto ampiamente disomogenei per natura delle lingue, qualità/quantità della documentazione, metodologia di approccio e apporti di carattere storico-culturale. In particolare per quanto concerne il venetico, accanto ad una rivisitazione critica di aspetti più generali, si propone una serie di tematiche derivanti dalle acquisizioni documentarie più recenti, soprattutto in relazione alla questione della classificazione linguistica, ed alla posizione del venetico nel quadro delle lingue indeuropee d’Italia
Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404 : im Canton Graubündten gezeichnet den 2. Sept 1874, zwischen 10 bis 1 Uhr Mittag
No full textvon J. Müller-Wegmann ; Lith. F. LipsSee bezeichnet mit: "Lago Retico 2378 mt - 30 Jucharten Flächeninhalt"Gehört zu den Ansichten und Panoramen, die früher als Doubletten bezeichnet wurden. Es handelt sich jedoch um feiner oder weiter ausgearbeitete Zeichnungen, Vorstufen zu Reinzeichnungen oder Sammlungsstücken, die bisher weder katalogisiert noch signiert wurdenVgl. "Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404 mt.Canton Graubündten", Signatur: [Müller-Wegmann] B 80; "Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404", Signatur: [Müller-Wegmann] XXIV 33 und "Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404", Signatur: [Müller-Wegmann] P 483Aus der Sammlung Johann Müller-Wegmann; Depositum der SAC Sektion Uto in der Zentralbibliothek des SA
Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404 : im Canton Graubündten gezeichnet den 2. Sept 1874, zwischen 10 bis 1 Uhr Mittag
No full textvon J. Müller-Wegmann ; Lith. F. LipsUnten rechts: Jahrbuch d. S.A.C. Band XVgl. "Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404 mt.Canton Graubündten", Signatur: [Müller-Wegmann] B 80; "Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404", Signatur: [Müller-Wegmann] P 4884 und "Gebirgsansicht ob dem Lago Retico am Cristallinapass 2404", Signatur: [Müller-Wegmann] P 483Aus der Sammlung Johann Müller-Wegmann; Depositum der SAC Sektion Uto in der Zentralbibliothek des SAC Exemplar der Zentralbibliothek Zürich, Zentralbibliothek SA
A scalable computer-aided detection system for microcalcification cluster identification in a pan-European distributed database of mammograms
No full textA computer-aided detection (CADe) system for microcalcification cluster identification in mammograms has been developed in the framework of the EU-founded MammoGrid project. The CADe software is mainly based on wavelet transforms and artificial neural networks. It is able to identify microcalcifications in different kinds of mammograms (i.e. acquired with different machines and settings, digitized with different pitch and bit depth or direct digital ones). The CADe can be remotely run from GRID-connected acquisition and annotation stations, supporting clinicians from geographically distant locations in the interpretation of mammographic data. We report the FROG analyses of the CADe system performances on three different dataset of mammograms, i.e. images of the CALMA INFN-founded database collected in the Italian National screening program, the M1AS database and the so-far collected MammoGrid images. The sensitivity values of 88% at a rate of 2.15 false positive findings per image (FP/im), 88% with 2.18 FP/im and 87% with 5.7 FP/im have been obtained on the CALMA, MIAS and MammoGrid database, respectively. (c) 2006 Elsevier B.V. All rights reserved. RI Retico, Alessandra /I-6321-201
Characterization of mammographic masses using a gradient-based segmentation algorithm and a neural classifier
No full textComputerized methods have recently shown a great potential in providing radiologists with a second opinion about the visual diagnosis of the malignancy of mammographic masses. The computer-aided diagnosis (CAD) system we developed for the mass characterization is mainly based on a segmentation algorithm and on the neural classification of several features computed on the segmented mass. Mass-segmentation plays a key role in most computerized systems. Our technique is a gradient-based one, showing the main characteristic that no free parameters have been evaluated on the data set used in this analysis, thus it can directly be applied to data sets acquired in different conditions without any ad hoc modification. A data set of 226 masses (109 malignant and 117 benign) has been used in this study. The segmentation algorithm works with a comparable efficiency both on malignant and benign masses. Sixteen features based on shape, size and intensity of the segmented masses are extracted and analyzed by a multi-layered perceptron neural network trained with the error back-propagation algorithm. The capability of the system in discriminating malignant from benign masses has been evaluated in terms of the receiver-operating characteristic (ROC) analysis. A feature selection procedure has been carried out on the basis of the feature discriminating power and of the linear correlations interplaying among them. The comparison of the areas under the ROC curves obtained by varying the number of features to be classified has shown that 12 selected features out of the 16 computed ones are powerful enough to achieve the best classifier performances. The radiologist assigned the segmented masses to three different categories: correctly-, acceptably- and non-acceptably-segmented masses. We initially estimated the area under ROC curve only on the first category of segmented masses (the 88.5% of the data set), then extending the classification to the second subclass (reaching the 97.8% of the data set) and finally to the whole data set, obtaining A(z)=0.805 +/- 0.030, 0.787 +/- 0.024 and 0.780 +/- 0.023, respectively. (c) 2007 Elsevier Ltd. All rights reserved. RI Retico, Alessandra /I-6321-201
Aquileia e l'entroterra venetico e retico: alcune considerazioni
No full textLe fonti antiche evidenziano la funzione emporica di Aquileia in epoca repubblicana
nei confronti delle regioni transalpine, prestando invece scarsa attenzione ai rapporti
con l’entroterra venetico e retico, che la documentazione archeologica e quella epigrafica
mostrano ben consolidati e organizzati. Alcuni elementi consentono di ipotizzare che tra
questi rientrassero le attività economiche connesse al fenomeno della transumanza tra gli
altipiani prealpini e la fascia rivierasca altoadriatica.The ancient sources emphasise the commercial role of Aquileia towards Transalpine regions
in Republican times, paying instead little attention to the relationships with the Venetic and
Rhaetic hinterland which archaeological and epigraphic evidence shows well established and
organised. Some elements allow to advance the hypothesis that also economic activities connected
to the transhumance between pre-Alpine highlands and Upper Adriatic coastal strip
were included among these relations
Characterization of a Single Photon Counting Imaging System by Transfer Function Analysis
No full textA method to quantitatively evaluate the performances of a radiographic detection system consists in measuring the contrast, noise and modulation transfer functions. These functions have been evaluated for a digital radiographic system based on a single photon counting pixel detector. The X-ray detector is a Silicon sensor with one side segmented in a matrix of 256 by 256 square contacts with a pitch of 55 mu m. The active area is about 2 cm(2). The sensor is connected to the Medipix2 read-out chip by bump-bonding. As X-ray source we have used a tube for general radiography. To reproduce the conditions of a radiographic examination, a 4 cm thick Incite block positioned above the detector has been used to simulate a tissue sample. To study the Contrast Transfer Function we have measured the contrast of an 1 mm thick lead slab with respect to the background. To evaluate the scattering contribution from the Incite, the measurements have been performed with and without a collimator placed at the beam exit. To assess the efficiency and noise transfer properties, we have measured the Detective Quantum Efficiency (DQE) of. the detector as a function of the tube voltage. The Modulation Transfer Function has been measured applying the slit method for different conditions of tube voltage and energy threshold. RI Retico, Alessandra /I-6321-201
Geografia e forme della divinazione nel Veneto preromano
No full textSi delinea un quadro della geografia oraoclare nel Veneto preromano e alle soglie della romanità.Sono tenuti presenti i documenti in venetico e in retico su diversi supporti epigrafici e viene sottolienate la loro associazione in particolari contesti non esclusivamente abitativi, né esclusivamente votivi.I dati dei rinveiemtni archeologici sono incrociati con le tetsimonianze delle fonti storiche di epoca classica
An automatic system to discriminate malignant from benign massive lesions in mammograms
No full textEvaluating the degree of malignancy of a massive lesion on the basis of the mere visual analysis of the mammogram is a non-trivial task. We developed a semi-automated system for massive-lesion characterization with the aim to support the radiological diagnosis. A dataset of 226 masses has been used in the present analysis. The system performances have been evaluated in terms of the area under the ROC curve, obtaining Az= 0.80 ± 0.04
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