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), 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
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.
The ARGO-YBJ detector layout, features and location offer a unique possibility for a detailed study of several characteristics of the hadronic component of the cosmic ray flux in an energy range ...hardly accessed by direct measurements. The proton-air cross section has already been measured by ARGO-YBJ in an energy region up to ~ 100 TeV where the primary cosmic ray composition is sufficiently well known for that measure to be unbiased. The analog readout of the RPC signals now provides new tools to measure the lateral distribution of particle density (LDF) as close as a few meters from the core and to investigate with unprecedented resolution the shower time structure. This allows to extend the hadronic interaction and mass composition studies up to ~PeV energies in the laboratory rest frame. Moreover, it is shown that the LDF of detected showers can be properly described, even very close to the shower axis, by a NKG-like function, whose shape parameter is clearly related to the shower age and can be used for studying the mass composition of cosmic rays.
ABSTRACT
OBJECTIVES
We detail a procedure for generating a set of templates for the hippocampal region in magnetic resonance (MR) 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 AMY experiment aims to measure the Microwave Bremsstrahlung Radiation (MBR) Twitter by air-showers secondary electrons accelerating in collisions with neutral molecules of the atmosphere. The ...measurements are performed at the Beam Test Facility (BTF) of Frascati INFN National Laboratories and the final purpose is to characterize the process to be used in a next generation detectors of ultra-high energy cosmic rays (up to 10 super(20)eV). We describe the experimental set-up and the first test measurement performed in November 2011.
To evaluate the safety and feasibility of supra-pubic percutaneous sclero-embolization (SE) in the treatment of symptomatic female pelvic varicocele (FPV), performed under local anesthesia.
The ...authors selected 28 patients screened by transabdominal and transvaginal ultrasound, with venous Doppler signal. Clinicians performed SE by transfemoral catheterization, under local anesthesia, using of a mix of 2 ml of lauromacrogol 400 (Atossisclerol 3%, Chemische F. Kreussler, Wiesbaden, Germany) and 2 ml of air, in a mixed foam fashion.
The total operative time for SE was 7.6 +/- 2.1 min. Intra-surgical blood loss was 40 +/- 14 ml. No migration of sclerosant material occurred and postoperative analgesic request during a 48 hr period occurred in 6 patients. Technical success was 100%. The Authors embolized 8 women bilaterally (28.5%), 18 on the left ovarian vein (OV) (64.2%) and 2 only in the right OV (7.1%): 7 women complained of transitory flank pain (25%), which disappeared in few minutes. The major complications in 10 days after SE were: fever (> 38 degrees C for two days) in 2 patients (7.1%) and pelvic pain for 3 days in eight patients (28.5%). After 30 days only 6 women suffered of FPV lower symptoms which disappeared in 180 days. A substantial reduction in size of pelvic varicosities was noted in all patients.
SE is a safe and feasible procedure. It reduces significantly the mean time of scopies, the intensity of radiation emission, and it is performed under local anaesthesia. This minimally invasive procedure could be proposed to all women with supra-pubic FPV for its reproducibility and feasibility.
The DArk Matter Particle Explorer (DAMPE), one of the four scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Sciences, ...is a general purpose high energy cosmic-ray and gamma-ray observatory, which was successfully launched on December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE scientific objectives include the study of galactic cosmic rays up to ∼ 10 TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the search for dark matter signatures in their spectra. In this paper we illustrate the layout of the DAMPE instrument, and discuss the results of beam tests and calibrations performed on ground. Finally we present the expected performance in space and give an overview of the mission key scientific goals.
Intrinsic differences in the processes involved in the electromagnetic and hadronic shower development in the atmosphere have been evidenced by means of a careful analysis of the event image given by ...the ARGO-YBJ detector. The images have been analyzed at different length scales and their multifractal nature has been studied. The use of the multiscale approach together with a properly designed and trained Artificial Neural Network, allowed us to obtain a good discrimination power. If confirmed by further studies on different event categories, this result would allow to nearly double the detector sensitivity to gamma-ray sources.
You The Air Microwave Yield (AMY) experiment investigate the molecular bremsstrahlung radiation emitted in the GHz frequency range from an electron beam induced air-shower. The measurements have been ...performed at the Beam Test Facility (BTF) of Frascati INFN National Laboratories with a 510 MeV electron beam in a wide frequency range between 1 and 20 GHz. We present the apparatus and the results of the tests performed.
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