Beniamino Castagnolo

Computer aided detection of microcalcifications in digital mammograms adopting a wavelet decomposition

Over recent years breast cancer prevention campaigns have resulted in widespread screening. Until now, mammography has been one of the most reliable methods for the early detection of this disease. The high correlation between the appearance of microcalcification clusters and the presence of cancer shows that Computer Aided Detection systems of microcalcifications are extremely useful and helpful in an early detection of breast cancer. Several techniques can be adopted to accomplish this task. In this paper an efficient tool for a fully automatic microcalcification cluster detection/localization is presented. Adopting this procedure, all suspect microcalcifications are preserved and background noise is reduced by thresholding mammograms through a wavelet filter, according to image statistical parameters (i.e. mean gray level pixel value and standard deviation). Moreover, in order to localize singularity points, the reconstructed image is decomposed adopting another wavelet and each decomposition level is processed using a hard threshold technique. To reduce false positive detections in microcalcification recognition, the results obtained in each level are combined with a suitable procedure. The Mammographic Image Analysis Society database is used to test the procedure. The performance obtained highlights the validity of the method; indeed, the evaluated sensitivity parameter (true positive rate) is about 98% at an average rate of 1 false positive per image.

Health Care Improvement: Comparative Analysis of Two CAD Systems in Mammographic Screening

Technological innovations have produced remarkable results in the health care sector. In particular, computer-aided detection (CAD) systems are becoming very useful and helpful in supporting physicians for early detection and control of some diseases such as neoplastic pathologies. In this paper, two different CAD systems able to detect and to localize microcalcification clusters in mammographic images are implemented. The two methods utilize an artificial neural network and a support vector machine, respectively, as classifier. Adopting the MIAS database as procedure testing, the performance of the two implemented systems are compared in terms of sensitivity, specificity, accuracy, free-response operating characteristic curves, and Cohens kappa coefficient. The obtained values for the previous parameters show the efficiency of both methods to operate as “second opinion” in microcalcification cluster detection, improving the screening process efficiency.

High-speed error correction circuit based on iterative cells

Abstract The implementation of a decoder for cyclic redundancy check codes at very high bit rates is suggested. It is based on a purely combinational, iterative cells circuit. The theoretical performance evaluation and the simulations show the enhancement in terms of operating speed with respect to the sequential solution.

Design of convolutional encoders for ultra high speed and optical communications

In this paper the implementation of a coding circuit for convolutionary codes is suggested. It is based on a purely combinational circuits composed of a cascade of iterative cells. The circuit modularity makes it suitable for an easy integration. The performance evaluation shows the enhancement in terms of operating speed and number of logic gates adopted, with respect to the sequential solution. As the designed encoder uses combinational circuits only, it results suitable for implementation in all-optical environment, too.

Starring: a multihop light-wave architecture with simple routing strategies

A minimal routing strategy for a new network architecture, named Starring, is presented. The simplicity of the proposed algorithm optimizes the expected average number of hops and hence the efficiency, of the network. Estimates of the network diameter and of the average number of hops in the Starring architecture show that, in the optimized operating mode, they compare fairly well with those related to other known photonic structures. The self-minimal routing behavior of the Starring and the possibility of an easy design and implementation of all-optical switching circuit make the Starring structure attractive and competitive.

New intensity GaAs electro-optic modulator realized by intersecting waveguides

An intersecting waveguide modulator which utilizes the carrier injection effects is presented and characterized. Using O+ implantation to render the implanted region electrically inactive, a well confined injection carrier channel is formed. This area can be driven to function as waveguide or as anti-waveguide. A transversal electrode switches the modulator from the on-state to the off-state or vice versa. By the use of carrier induced refractive index modeling and the finite difference beam propagation method simulation, good performance and small injection current of this modulator are predicted.

A new chirped grating for deflecting and focusing guided waves

A novel binary chirped grating that could be used as an integrated deflecting-focusing lens is presented. The diffractive focusing function of the grating can be realized by the interference of input and output wavefronts. It has the combined characteristics of deflector and lens. Numerical examples of design of binary grating lenses are presented together with computer simulations, which allow one to expect high coupling efficiencies.

Switching elements based on the spatial optical soliton propagation

the soliton generation and trapping in nonlinear waveguide can be used to implement ultrafast, all-optical switches. In this paper, the phenomenon of the soliton emission from a nonlinear interface of a symmetrical waveguide and of the soliton trapping are analyzed by simulations performed using the beam propagation method. We show the correlation between the input optical power and the length at which the soliton generation occurs, along the propagation direction of the single-mode nonlinear waveguide. Based on these principles, new all-optical switching elements and logical gates can be designed, which exhibit many important advantages on the classical electro-optical devices.

Analysis and design of large optical interconnection networks

M X N generalized shuffle networks are generally constituted by arrays of m X n switches linked together by an interconnection network. The number of stages necessary to obtain all the possible input-output links is very low. Therefore, they can be easily implemented on LiNbO3 crystals because the overall network length is reduced even if the transversal dimension is slightly increased. The architecture of such a shuffle network is presented here and its performance, in terms of networks cost, throughput, and bandwidth, is evaluated. The possible elementary switches are outlined.

Analysis and simulation of photonic switch networks

In this paper lange dimension photonic switching networks and their performances are analyzed. The characteristics of completeness, planarity, reconfiguration times, non-blocking, and the fault-tolerance property are taken into account. The shuffle type interconnection network results the better choice. Moreover, the control algorithm is considered, and the results of the simulations performed by a digital computer are given.