477 research outputs found
A project of digital mammograph based on GaAs pixel detector and on a self-triggering single photon counting acquisition system
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Resolving clinicians queries across a grid infrastructure
No full textF. Estrella (1) , C. del Frate (2) , T. Hauer (1), R. McClatchey (1) , M. Odeh (1) , D. Rogulin (1) , S. R. Amendolia (3), D. Schottlander (4) , T. Solomonides (1) , R. Warren(5
A Novel morphological approach to volume extraction in 3D tomography
No full textExtracting a region of interest from volumetric data represents an important task in the field of digital image analysis. Several approaches to this problem are proposed in literature. The present paper affords volume extraction for regions of interest whose characteristics are not known a-priori. This is the case, for instance, of cancerous tissues in medical tomography or defects in industrial tomography. The technique here described allows extraction of completely arbitrary shapes with a minimum interaction with the user. The volume of interest is defined through the semi-automatic selection of a small set of rail contours at different planes. Such contours are then blended through a morphing technique in order to interpolate the cutting surface. The overall technique demonstrates to be intuitive, efficient and robust. Some results are reported where the method has been applied to micro-tomographic measurements
Images of soft materials: a 3D visualization of interior of the sample in terms of attenuation coefficient
No full textImages of soft materials are obtained using image intensifier based X-ray system (Rao et al., Nucl. Instr. and Meth. A 437 (1999) 141). The interior of the soft material is visualized using the novel software in order to know the distribution of attenuation coefficient in terms of density. The novel software is based mainly on graphical library and applicable to several operating systems without any change. It can be applied to several applications starting from biomedical to industries, for example, quality control. The results for walnut and brew tooth are presented as a set of images from the internal parts of the sample. A description of the principal parameters required for tomographic visualization is given and some results based on this technique are reported and discussed
Observation of Top Quark Production in ¯pp Collisions with the CDF Detector at Fermilab
No full textWe establish the existence of the top quark using a 67 pb \Gamma1 data sample of ¯ pp collisions at p s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with t ¯ t decay to WWb ¯ b, but inconsistent with the background prediction by 4:8oe. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be 176 \Sigma 8(stat:) \Sigma 10(sys:) GeV/c 2 , and the t ¯ t production cross section to be 6:8 +3:6 \Gamma2:4 pb. The CDF Collaboration F. Abe, 14 H. Akimoto, 32 A. Akopian, 27 M. G. Albrow, 7 S. R. Amendolia, 24 D. Amidei, 17 J. Antos, 29 C. Anway-Wiese, 4 S. Aota, 32 G. Apollinari, 27 T. Asakawa, 32 W. Ashmanskas, 15 M. Atac, 7 P. Auchincloss, 26 F. Azfar, 22 P. Azzi-Bacchetta, 21 N. Bacchetta, 21 W. Badgett, 17 S. Bagdasarov, 27 M. W. Bailey, 19 J. Bao, 35 P. ..
Numerical Simulation for eHealth: Grid-enabled Medical Simulation Services
No full textThe European GEMSS Project is concerned with the creation of medical Grid service prototypes and their evaluation in a secure service oriented infrastructure for distributed on demand supercomputing the GEMSS testbed. The medical prototype applications include maxillofacial surgery simulation, neurosurgery support, radiosurgery planning, inhaled drug delivery simulation, cardiovascular simulation and tomographic image reconstruction. GEMSS will enable the widespread use of these computationally demanding tools originating from projects such as BloodSim, SimBio, COPHIT and RAPT as Grid services. The numerical High Performance Computing core includes parallel Finite Element software and Computational Fluid Dynamics simulation as well as parallel optimization methods and parallel Monte Carlo simulation. Targeted enduser groups include biomechanics laboratories, hospital surgery/radiology units, diagnostic and therapeutic departments, designers of medical devices in industry as well as small enterprises involved in consultancy on biomedical simulations. GEMSS addresses security, privacy and legal issues related to the Grid provision of medical simulation and image processing services and the development of suitable business models for sustainable use. The first prototype of the GEMSS middleware is expected to be released in February 2004
Characterization of a mammographic system based on single photon counting pixel arrays coupled to GaAs x-ray detectors
No full textThe authors report on the imaging capabilities of a mammographic system demonstrator based on GaAs pixel detectors operating in single photon counting (SPC) mode. The system imaging performances have been assessed by means of the transfer functions: The modulation transfer function (MTF), the normalized noise power spectrum, and the detective quantum efficiency (DQE) have been measured following the guidelines of the IEC 62220-1-2 protocol. The transfer function analysis has shown the high spatial resolution capabilities of the GaAs detectors. The MTF calculated at the Nyquist frequency (2.94 cycles/mm) is indeed 60%. The DQE, measured with a standard mammographic beam setup (Mo/Mo, 28 kVp, with 4 mm Al added filter) and calculated at zero frequency, is 46%. Aiming to further improve the system's image quality, the authors investigate the DQE limiting factors and show that they are mainly related to system engineering. For example, the authors show that optimization of the image equalization procedure increases the DQE(0) up to 74%, which is better than the DQE(0) of most clinical mammographic systems. The authors show how the high detection efficiency of GaAs detectors and the noise discrimination associated with the SPC technology allow optimizing the image quality in mammography. In conclusion, the authors propose technological solutions to exploit to the utmost the potentiality of GaAs detectors coupled to SPC electronics
Comparison of imaging properties of several digital radiographic systems
No full textDigital radiography is a field of great interest; a wide range of different imaging systems is now becoming available and it is very important to have powerful instruments to characterize and compare their imaging properties. We have evaluated imaging properties for several digital radiographic systems in terms of resolution and noise properties. For the resolution properties, we have used the Modulation Transfer Function (MTF) and the presampling MTF, for undersampled systems. We have characterized noise properties by Detective Quantum Efficiency, that is an absolute parameter that allows comparison between different systems
The CALMA project: a CAD tool in breast radiography
No full textIn this paper we present the Computer-Aided Library for MAmmography (CALMA Project), i.e. an automated search for the mammograms' texture, the massive lesions and microcalcifications clusters. CALMA's main purpose is to collect a database of mammographic images, developing CAD tools to be used as a second radiologist in the classification of breast cancer diseases. In this moment, 2200 images are already in our database, which is, to our knowledge, the largest in Europe. One-third of our digitized images are pathological, and they are fully characterized by a consistent description and diagnosis. We try to perform automatically the classification of mammographic images on the bases of tissues' textures. Such a classification should be done in an unbiased way with respect to radiologists and should support their interpretation of the mammographic image. Results obtained with non supervised neural networks are shown, as well as results coming from a mixed approach (features extraction combined with FF-ANN). Massive lesions are rather large objects to be detected, but they show up with a faint contrast slowly increasing with time. The need for tools able to recognize such a lesion at an early stage is therefore apparent. Our tools are based on a ROI hunter procedure for spiculated lesions showing a number of false positives of the order of 1.4 per image and keeping a 85% sensitivity on our sample. A microcalcication is a rather small (0.1-1.0 mm in diameter) but very brilliant. Some of them, either grouped in cluster or isolated may indicate the presence of a tumor. Up to now only 40 images with microcalcications from our database have been analyzed, and a CAD tool has been designed to detect clusters, reaching a correct classification of 90%. (C) 2001 Elsevier Science B.V. All rights reserved
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