Maria Rizzi

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.

Improving energy efficiency in building system using a novel people localization system

This paper presents an innovative Bluetooth Low Energy indoor localization system useful to improve energy efficiency in buildings. A tracking system to localize people within a building has been developed using a novel infrastructure system and a custom signal processing method. Knowledge whether people are present or not in every room enables the automatic switching-off of lighting and heating/cooling in empty room increasing the energy efficiency of building system. The implemented method achieves performance comparable to that of a traditional Bluetooth Low Energy indoor location system, nevertheless fewer devices are used. As a result, the cost of installation in existing building decreases.

Computer Aided Evaluation (CAE) of Morphologic Changes in Pigmented Skin Lesions

Mole pattern changes are important elements in detecting cancerous skin lesions, the early stage detection is a key factor to completely cure the pathology. In this paper, an automatic system for mole-tracking is indicated. The method presented is been realized as a mobile app and can be used to perform periodically a careful self-examination of their pigmented skin lesions. The implemented method receives in input two segmented images of the same pigmented skin lesion corresponding to the actual image and to the image before the last period under test. The method performs image matching and changes evaluation adopting a three stage artificial neural network and provides as output a risk indicator related to the morphology changes of the skin lesion.

A Marker-Based Image Processing Method for Detecting Available Parking Slots from UAVs

Due to the considerable number of vehicles in many cities, parking problem is a long-term phenomenon and represents one of the main causes of traffic congestion. Unmanned Aerial Vehicles (UAVs) can handle automatic monitoring of traffic, pollution and other interesting services in urban areas non-invasively. UAVs are usually equipped with one or more onboard cameras and with other electronic sensors. In this context, a method for parking slot occupancy detection in parking areas is presented. For recognition of free parking spaces, pictures of urban areas captured by the onboard camera of the UAV are georeferenced and processed for marker detection. The implemented system shows good results in terms of robustness and reliability. Moreover, it paves the way for an improved management of urban spaces.

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.

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.

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.

An innovative LPWA network scheme to increase system reliability in remote monitoring

This paper presents a smart system based on Low Power Wide Area networks for a remote monitoring of technological room in unstaffed railway stations. The paper aim is the design of an efficient network scheme characterized by improved performance compared with the standard solution. Adopting an innovative smart System Control Strategy and a custom network topology, good results are reached in terms of reliability without increasing the amount of devices with respect the standard scheme.