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This work is a part of the MAGIC-5 (Medical Applications on a Grid Infrastructure Connection) experiment of the Italian INFN (Istituto Nazionale di Fisica Nucleare). A simple CAD (Computer-Assisted Detection) system for juxta-pleural lung nodules in CT images is presented, with the purpose of comparing different 2D concavity-patching techniques and assessing the respective efficiency in locating nodules. After a short introduction on the motivation, and a review of some CAD systems for lung nodules already published by the MAGIC-5 Collaboration, the paper describes the main lines of this particular approach, giving preliminary results and comments. In our procedure, candidate nodules are identified by patching lung border concavities in a hierarchical multiscale framework. Once located, they are fed to an artificial neural network for false positive reduction. The system has a modular structure that easily allows the insertion of arbitrary border-smoothing functions for concavity detection and nodule searching. In this paper the α-hull and morphological closing are compared, proving the higher sensitivity of the former, which also appears computationally less heavy. © 2010 Elsevier B.V. All rights reserved.

The mammography is the most effective procedure for an early diagnosis of the breast cancer. In this paper, an algorithm for detecting masses in mammographic images will be presented. The database consists of 3762 digital images acquired in several hospitals belonging to the MAGIC-5 collaboration (Medical Applications on a Grid Infrastructure Connection). A reduction of the whole image's area under investigation is achieved through a segmentation process, by means of a ROI Hunter algorithm, without loss of meaningful information. In the following classification step, feature extraction plays a fundamental role: some features give geometrical information, other ones provide shape parameters. Once the features are computed for each ROI, they are used as inputs to a supervised neural network with momentum. The output neuron provides the probability that the ROI is pathological or not. Results are provided in terms of ROC and FROC curves: the area under the ROC curve was found to be Az=0.862plusmn0.007, and we get a 2.8 FP/Image at a sensitivity of 82%. This software is included in the CAD station actually working in the hospitals belonging to the MAGIC-5 Collaboration

A completely automated system for the identification of pleural nodules in low-dose and thin-slice computed tomography (CT) of the lung has been developed. The directional-gradient concentration method has been applied to the pleura surface and combined with a morphological opening-based procedure to generate a list of nodule candidates. Each nodule candidate is characterized by twelve morphological and textural features, which are analyzed by a rule-based filter and a neural classifier. This detection system has been developed and validated on a dataset of 42 annotated CT scans. The k-fold cross validation has been used to evaluate the neural classifier performance. The system performance variability due to different ground truth agreement levels is discussed. In particular, the poor 44% sensitivity obtained on the ground truth with agreement level 1 (nodules annotated by only one radiologist) with 6 FP per scan grows up to the 72% if the underlying ground truth is changed to the agreement level 2 (nodules annotated by two radiologists).

A study of the problem of deterioration of a historical monument, the Crypt of the "Cattedrale di Otranto” (Lecce, South Italy), integrating different non destructive techniques (microclimatic and Ground Penetrating Radar) is proposed. In literature the degradation of stone is attributed to the presence of water and/or moisture in the porous material that occurs in water-damaged and humid buildings, due to poorly manufactured constructions and inadequate maintenance. The distribution of moisture within stone mainly depends on unsuitable environmental conditions and the presence of wet buried structures in the ground. After microclimatic surveys, through which we assessed unsuitable condition in the Crypt, Ground Penetrating radar (GPR) surveys were carried out. A careful analysis of the 0.4 m spaced GPR parallel profiles, acquired in the Crypt using a Sir2 GSSI radar system with a 500 MHz antenna, allow us to distinguish the wet and the moisture zone. GPR data was displayed in time slices form to obtain both the amplitude and the moisture variations map. Moreover GPR data was displayed in the form of frequency slices to highlight absorption losses probably related to higher moisture content. Therefore the GPR data was compared with the microclimatic data, and a good agreement was found, suggesting that an important channelling of moisture has its origin in the subsoil.

Mass localization plays a crucial role in computer-aided detection (CAD) systems for the classification of suspicious regions in mammograms. In this article we present a completely automated classification system for the detection of masses in digitized mammographic images. The tool system we discuss consists in three processing levels: (a) Image segmentation for the localization of regions of interest (ROIs). This step relies on an iterative dynamical threshold algorithm able to select iso-intensity closed contours around gray level maxima of the mammogram. (b) ROI characterization by means of textural features computed from the gray tone spatial dependence matrix (GTSDM), containing second-order spatial statistics information on the pixel gray level intensity. As the images under study were recorded in different centers and with different machine settings, eight GTSDM features were selected so as to be invariant under monotonic transformation. In this way, the images do not need to be normalized, as the adopted features depend on the texture only, rather than on the gray tone levels, too. (c) ROI classification by means of a neural network, with supervision provided by the radiologist's diagnosis. The CAD system was evaluated on a large database of 3369 mammographic images [2307 negative, 1062 pathological (or positive),more » containing at least one confirmed mass, as diagnosed by an expert radiologist]. To assess the performance of the system, receiver operating characteristic (ROC) and free-response ROC analysis were employed. The area under the ROC curve was found to be A{sub z}=0.783{+-}0.008 for the ROI-based classification. When evaluating the accuracy of the CAD against the radiologist-drawn boundaries, 4.23 false positives per image are found at 80% of mass sensitivity.« less

The use of automatic systems in the analysis of medical images has proven to be very useful to radiologists, especially in the framework of screening programs, in which radiologists make their first diagnosis on the basis of images only, most of those corresponding to healthy patients, and have to distinguish pathological findings from non-pathological ones at an early stage. In particular, we are developing preprocessing methods to be applied for pulmonary nodule Computer Aided Detection in low-dose lung Multi Slice CT (computed tomography) images.

Silica thin films have been deposited by a dual-ion-beam sputtering technique using argon or xenon ions mixed with oxygen ions in the assisting beam and the role of the assisting-ion-beam parameters on the laser-damage-threshold at 308 nm (XeCl laser) has been investigated. It is shown that a proper choice of these parameters allows a considerable increase of the laser-induced damage threshold. Lower damage thresholds (1 J/cm 2 ) were found for the xenon/oxygen assisted samples. Whereas, the highest damage threshold (8 J/cm 2 ) was found for the argon-ion assisted sample and its value was also much higher than that (2.9 J/cm 2 ) of the non-assisted films. Damage thresholds have been determined by the photoacoustic mirage technique and it is demonstrated that this technique can provide useful information on the mechanisms responsible for laser damage.

SiO2 films have been deposited by ion-beam sputtering techniques either without assistance or with Ar-ion assistance and the role of the substrate temperature during the deposition process on the film damage threshold by laser light at the wavelength of 308 nm (XeCl) has been investigated. The photoacoustic probe beam deflection technique has been used to determine damage thresholds and it is shown that this technique provides valuable information on the mechanisms leading to laser damage. It has been found that the samples deposited by the Ar-ion beam sputtering technique are characterized by higher damage thresholds at lower temperatures of the substrate than the SiO2 films deposited without ion assistance.

A XeCl laser delivering circularly polarised laser pulses with quite low beam-quality factor ( M 2 ≅4) is focused in H 2 to generate rotational and vibrational lines by stimulated Raman scattering processes. The efficiency for generation of the first rotational line S 01 at 313.7 nm ( v =0, J =1→ v =0, J =3) is improved by tightly focusing the pump beam in the Raman cell as a consequence of vibrational Raman gain suppression.

is investigated with a XeCl laser. It is shown that energy conversion to rotational Stokes radiation can be efficiently obtained by properly choosing the focusing geometry of pump radiation and the pressure of the Raman medium even at moderate pulse energies. Energy conversion to the first rotational Stokes at 313.8 nm with efficiencies as high as 38% is obtained with a circularly polarised XeCl pump beam of 10-mJ energy focused in 30 bar of H2. The spectral and optical characteristics of the pump and the rotational Stokes radiation are analysed.

Stimulated rotational and vibrational Raman scattering in H/sub 2/ was investigated with a circularly and a linearly polarized XeCl laser beam and the influence of the focusing geometry on the threshold for rotational and vibrational scattering, respectively, was studied. It is shown that with a circularly polarized pump beam a high-angle focusing geometry allows to get only rotational Raman scattering, whereas a low-angle focusing geometry provides only vibrational Raman scattering for gain suppression effects.

A plane-parallel cavity with a Gaussian reflectivity mirror has been applied to a XeCl laser medium having a spatially variable gain distribution. The evolution of the beam parameters has been experimentally analyzed as a function of the number of round trips. It is shown that in this case of intensity profiles affected by the spatial and temporal properties of the active medium gain, a theory formerly developed for the beam-parameter evolution of Gaussian Schell-model beams provides a satisfactory description of experimental measurements for the first few round trips.

Objectives We detail a procedure for generating a set of templates for the hippocampal region in Magnetic Resonance images, representative of the clinical conditions of the population under investigation. Methods The first step is robust standardization of the intensity scale of brain MR images, belonging to patients with different degrees of neuropathology (Alzheimer’s Disease). So similar tissues have similar intensities, even across images coming from different sources. After the automatic extraction of the hippocampal region from a large dataset of images, we address template generation, choosing by clusterization methods a small number of the extracted regions. Results We assess that template generation is largely independent on the clusterization method and on the number and the clinical condition of the patients. The templates are chosen as the most representative images in a population. The estimation of the ‘minimum’ number of templates for the hippocampal region can be proposed, using a metric based on the geometrical position of the extracted regions. Conclusions This study describes a simple and easily reproducible procedure to generate templates for the hippocampal region. It can be generalized and applied to other brain regions, which may be relevant for neuroimaging studies.

The focus of experimental and theoretical works about crystalline Acetanilide has been the “anomalous” temperature-dependent ir absorption and Raman peaks at about 1650 cm−1 and the multiband structure in the N-H stretch region. A lively discussion about the assignment of these “anomalous” bands has arisen and is still in progress. The present Raman experiments should be placed in this context as an attempt to identify the molecular degrees of freedom which originate the “anomalous” bands. In this aim Raman experiments have been performed on specifically deuterated Acetanilide [C6D5-CONH-CD3] single crystal in the low-frequency (phonon) and C=O stretching regions. On cooling a distinct band at about 1495 cm−1 increases in intensity. We assign this peak to the equivalent of the 1650 cm−1 band in Acetanilide. The temperature dependence of this Raman line was studied. The results are discussed in the light of the models proposed to explain the anomalous behaviour of the 1650 cm−1 Raman line in Acetanilide.

A new investigation of the temperature dependence of the far-infrared spectra of acetanilide and some isotopomers is presented. Four absorption bands are considered at 31, 42, 64, and 80 cm −1 , and no significant change of their integrated intensity is observed when reducing the temperature. The temperature induced frequency shift values and other properties of these bands are consistent with an assignment as anharmonic lattice phonons. These results rule out the assignment of the 64, 80, and 106 cm −1 bands as normal modes of the polaronic excitation, as previously suggested.

SiO2 thin films of 240 nm thickness have been deposited by a dual-ion-beam sputtering technique using argon or xenon ions mixed with oxygen ions in the assisting ion beam and the role of the assisting ion beam and of the substrate temperature on the laser damage threshold at 308 nm (XeCl excimer laser) has been investigated by the photo acoustic mirage technique. It has been found that the laser damage threshold was quite dependent on the film deposition conditions. The sample grown at a substrate temperature of 300 °C and with the argon ion assisting beam was characterized by the highest damage threshold (≅ 10 J/cm2).

Phase-unifying mirrors are optical components used as output couplers in laser resonators to improve the quality of the output laser beam (1,2). These components exhibit a high reflectance on a central area and a very low reflectance on an external area of the sample surface, with a sharp edge between the two zones. Their peculiarity is that the laser beam transmitted through the two areas does not suffer of phase distortions that means the jump, in the phase shift, is reduced to a minimum value.

The MAGIC-5 Project aims at developing Computer Aided Detection (CAD) software for Medical Applications on distributed databases by means of GRID Services. The use of automated systems for analyzing medical images has been demonstrated to improve the radiologist performance. In addition, it could be of paramount importance in screening programs, due to the huge amount of data to check and the cost of related manpower. The need for acquiring and analyzing data stored in different locations requires the use of GRID Services for the management of distributed computing resources and data. GRID technologies allow remote image analysis and interactive online diagnosis, with a relevant reduction of the delays presently associated to the diagnosis in screening programs. The MAGIC-5 project develops algorithms for the analysis of mammographies for breast cancer detection, Computed-Tomography (CT) images for lung cancer detection and Positron Emission Tomography (PET) imaging for the early diagnosis of the Alzheimer Disease (AD). We plan to configure a Virtual Organization (VO), so that authorized users can share data and resources and implement the following use cases: screening, tele-training and tele-diagnosis for mammograms and lung CT scans; statistical diagnosis by comparison of candidates to a distributed data-set of negative PET scans for the diagnosis of the Alzheimer Disease. A smallscale prototype of the required GRID functionality was already implemented for the analysis of digitized mammograms.

The effects of climate, pollution and human negligence cause severe and sometimes irreversible damage to buildings and monuments of cultural interest. It is well known that the presence of water and/or moisture content in a porous material is the initial cause of deterioration. In a previous paper, the authors reported an integrated study on a building of cultural importance, namely the crypt of the Cattedrale di Otranto in Apulia, Italy, based on non-destructive integrated biological and physical surveys. The method described was able to identify the ‘internal’ factors responsible for deterioration. It was discovered that the distribution of moisture in the stone depended mainly on adverse environmental conditions, and the presence of wet buried structures in the ground. The first aim of the present study was to identify subsurface water-content in this same crypt using a ground-penetrating radar (GPR) technique, and to compare these results with those of the previous microclimatic survey. In particular, the existence of underground discontinuities was verified; we located them and analysed their influence. Moreover, by means of velocity analysis, we obtained a quantitative estimate of the volumetric water-content under the pavement of the crypt. This finding completes the results of the previous research, as it indicates the causes of the deterioration in the crypt and provides significant information, on the basis of which, effective decisions can be made for safeguarding the historic building.

We present a new percolative approach which simulates degradation towards failure of metallic or insulating thin films. The thin film is modelled as a two-dimensional random resistor network in thermal contact with a substrate. Its degradation is characterized by a breaking probability of the single resistor related to the substrate temperature and to Joule heating effects. The dependence of the single resistor on the local temperature is taken into account as well as its thermal interaction with nearest neighbours. The failure of metallic strips and ultra-thin dielectrics are then described as a conductor-insulator (CI) and an insulator-conductor (IC) transition, respectively. A recovery of the damage competing with the degradation is introduced which accounts for healing processes and can eventually lead to a steady-state condition. This approach can model the resistance degradation of metal interconnects by electromigration phenomena and the pre-breakdown of ultrathin dielectric where stress induced leakage currents (SILC) are used to monitor the degradation. The main features of experiments are reproduced together with their statistical properties. Our approach thus provides a unified framework for studying degradation and failure in both metallic and dielectric thin films.

The performance of a 0.45 J KrF excimer laser with an unstable cavity using a phase-unifying mirror as an output coupler is described. The output beam having a cross section of 2.4×1.2 cm2 exhibits a smooth far field profile with 86.5% of the total near field energy contained within a far-field full angle θ⩽0.05 mrad. The measurements for determining the beam quality factor M2 and the beam angular stability are also reported.

A new algorithm for massive lesion detection in mammography is presented. The algorithm consists in three main steps : 1) reduction of the dimension of the image to be processed through the identifi cation of regions of interest (rois) as candidates for massive lesions ; 2) characterization of the roi by means of suitable feature extraction ; 3) pattern classifi cation through supervised neural networks. Suspect regions are detected by searching for local maxima of the pixel grey level intensity. A ring of increasing radius, centered on a maximum, is considered until the mean intensity in the ring decreases to a defi ned fraction of the maximum. The rois thus obtained are described by average, variance, skewness and kurtosis of the intensity distributions at diff erent fractions of the radius. A neural network approach is adopted to classify suspect pathological and healthy pattern. The software has been designed in the framework of the infn (Istituto Nazionale Fisica Nucleare) research project gpcalma (Grid Platform for calma) which recruits physicists and radiologists from diff erent Italian Research Institutions and hospitals to develop software for breast and lung cancer detection.