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This study investigated the radiation dose to surgeon eye lens for single procedure and normalised to exposure parameters for eight selected neuroradiology, cardiovascular and radiology interventional procedures.The procedures investigated were diagnostic study, Arteriovenous Malformations treatment (AVM) and aneurysm embolization for neuroradiology procedures, Coronary Angiography and Percutaneous Transluminal Coronary Angioplasty (CA-PTCA), Pacemaker and Implantable Cardioverter-Defibrillator implantation (PM-ICD), Endovascular Aortic Repair (EVAR) and Fenestrated Endovascular Aortic Repair (FEVAR) for cardiovascular and electrophysiology procedures. CT-guided lung biopsy was also monitored. All procedures were performed with table-mounted and ceiling-suspended shields (0.5 mm lead equivalent thickness), except for FEVAR and PM-ICD where only a table mounted shield was present, and CT-guided lung biopsy where no shield was used. Dose assessment was performed using a dosemeter positioned close to the most exposed eye of the surgeon, outside the protective eyewear.The surgeon most exposed eye lens median HIn interventional procedures, the 20 mSv/year dose limit for surgeon eye lens exposure might be exceeded if shields or protective eyewear are not used. Surgeon eye lens doses, normalised to single procedures and to exposure parameters, are a valuable tool for determining appropriate radiation protection measures and dedicated eye lens dosemeter assignment.

Subclinical and clinical thrombosis of bioprosthetic cardiac valves is more common than has been previously recognized. We present a unique case of acute thrombosis of a bioprosthetic mitral valve in a 40-year-old female patient undergoing hormonal stimulation as part of in vitro fertilization therapy, who also had concomitant protein C deficiency that was undiagnosed at the time. To the best of our knowledge, this is the first reported case of acute bioprosthetic valve thrombosis in this complex thrombophilic milieu, and suggests the need for increased screening for prothrombotic risk factors in female patients with bioprosthetic valves before they commence gonadotropin stimulation therapy.

Purpose The iterative reconstruction techniques have been proposed for decades to improve the quality of CT images and to reduce the quantum noise, dose and artefacts. This work evaluated the variability of the image quality by varying the strength of the adaptive iterative dose reduction in 3D algorithm (AIDR 3D) and how this was reflected in the dose delivered to patient. Materials and Methods 3D AIDR is an iterative algorithm, integrated in the acquisition procedure to ensure dose reduction. We assessed image noise, linearity and accuracy of CT numbers, the spatial resolution with dedicated phantom (Catphan503) varying the strength of the algorithm. Introducing the 3D AIDR algorithm in the acquisition phase, the dosimetric index, CTDIvol, was monitored. For some clinical cases, the images were reconstructed retrospectively with AIDR 3D and the diagnostic quality of the image was assessed by an expert radiologist. Results We acquired images of Catphan503 without the iterative algorithm. These images were reconstructed with different algorithm strength. The images were analyzed by ImageJ to extract the physical parameters. The accuracy of the CT number of the different materials included in the Catphan503 does not vary with the strength of the iterative algorithm. It has been verified that the image noise is reduced by about 40% by introducing the 3D AIDR Standard and a further 8% by AIDR 3D Strong. MTF value was reduced compared to images reconstructed by FBP algorithm of about 3%, 4.5% and 7% in images reconstructed respectively by AIDR Mild, AIDR Standard and AIDR Strong iterative algorithm. The dosimetric index was reduced of approximately 50% when the images were acquired by the iterative algorithm integrated in the acquisition phase. SNR of a uniform region of clinical images was increased compared to images reconstructed by FBP algorithm of about 60%, 67% and 73% in images reconstructed respectively by AIDR Mild, AIDR Standard and AIDR Strong iterative algorithm. Conclusions The algorithm preserved the physical parameters of the image. The radiologist involved in this study has not found a significant loss of quality diagnostic image.

This study evaluated the impact of influenza and vaccination coverage in Apulia, Italy, during the 2004–2005 and 2005–2006 seasons, using epidemiological and virological surveillance data collected through the Italian Net of Surveillance of Influenza (InfluNet) organized by the Superior Institute of Health (ISS) and the Inter-University Centre of Research on Influenza (CIRI). Vaccination coverage was calculated from the number of doses administered to individuals aged ≤ 65 years. Sentinel physicians reported weekly influenza-like illness (ILI) and acute respiratory illness (ARI) occurrences among patients. Influenza viruses were isolated and identified by cell culture on Madin-Darby Canine Kidney cells and polymerase chain reaction techniques. Vaccination coverage reached 72.7% and 77.0% during the 2004–2005 and 2005–2006 seasons, respectively. Incidence of ILI was higher during the 2004–2005 season compared with the 2005–2006 season, whereas the incidence ARI appeared to show a more constant trend. Incidence rates for ILI and ARI were higher in the 0 − 14-year age group. The increase in vaccination coverage and implementation of a network of epidemiological and virological surveillance are fundamental for the control and prevention of influenza.

We evaluated the diagnostic performance of a genomic DNA amplification method for Bordetella pertussis and Bordetella parapertussis compared with culture isolation. Aliquots from B. pertussis and B. parapertussis cultures were added to sterile physiological saline or sterile distilled water to give bacterial suspensions of 108 cells/ml and serial dilutions were prepared. Suspensions in physiological saline were cultured on charcoal agar medium; bacterial growth was observed up to dilutions of 10−7. Suspensions in distilled water were subjected to DNA extraction and nested polymerase chain reaction (PCR) was performed on the extracts; the PCR was positive up to dilutions of 10−8 for B. pertussis and 10−9 for B. parapertussis. Since the efficacy of culture isolation, regarded as the standard for the detection of B. pertussis and B. parapertussis, declines after the first stage of pertussis or with prior vaccination or antibiotic therapy, PCR, although not yet standardized, may provide an alternative diagnostic tool.

We present some results obtained with silicon and gallium arsenide pixel detectors to be applied in the field of digital mammography. Even though GaAs is suitable for medical imaging applications thanks to its atomic number, which allows a very good detection efficiency, it often contains an high concentrations of traps which decrease the charge collection efficiency (CCE). So we have analysed both electrical and spectroscopic performance of different SI GaAs diodes as a function of concentrations of dopants in the substrate, in order to find a material by which we can obtain a CCE allowing the detection of all the photons that interact in the detector. Nevertheless to be able to detect low contrast details, efficiency and CCE are not the only parameters to be optimized; also the stability of the detection system is fundamental. In the past we have worked with Si pixel detectors; even if its atomic number does not allow a good detection efficiency at standard thickness, it has a very high stability. So keeping in mind the need to increase the Silicon detection efficiency we performed simulations to study the behaviour of the electrical potential in order to find a geometry to avoid the risk of electrical breakdown.

Background: The overuse of antimicrobials is one of the main factors responsible for the development and spread of antimicrobial resistance, together with other causes, such as intra- and inter-hospital spread of resistant microorganisms and infection control policies and practices. The objective of the present study is to report the trends of Klebsiella pneumoniae and Acinetobacter baumannii antimicrobial resistance indicators in an Italian intensive care unit (ICU) during a six-year period, from 2008 to 2013. Methods: Susceptibility data and annual antibiotic consumptions in the ICU were retrospectively obtained from the clinical laboratory and the pharmacy. Trends over time of resistance rates (RRs) and of incidence densities of resistant isolates were determined by linear regression. Results: Isolation density of A. baumannii increased significantly from 2008 (20.4 per 1,000 patient-days) to 2013 (58.1 per 1,000 patient-days) and of K. pneumoniae from 2010 (22.3 per 1,000 patient-days) to 2013 (55.9 per 1,000 patient-days). RRs of third-generation cephalosporins (3GCs)-resistant K. pneumoniae (from 2010: 41.9 %, to 2012: 87.0 %), of carbapenem-resistant K. pneumoniae (from 2008: 0 %, to 2013: 59.2 %), and of carbapenem-resistant A. baumannii (from 2008: 87.5 %, to 2013: 96.6 %) showed significant increasing trends. Carbapenems was the main antibiotic class consumed (24.9 % of the total antimicrobial usage density), followed by 3GCs (21.0 %), fluoroquinolones (20.6 %), aminoglycosides (17.3 %), penicillins (15.1 %) and glycopeptides (1.1 %). Carbapenems consumption decreased from 2008 to 2012 and then increased in 2013. Glycopeptides consumption decreased from 2008 to 2011 and then increased in 2013. Aminoglycosides consumption decreased from 2008 to 2010 and increased from 2012 to 2013. Finally, 3GC, penicillins and fluoroquinolones consumptions decreased from 2012 to 2013. Conclusions: RRs of carbapenem-resistant A. baumannii and of carbapenem- and 3GC-resistant K. pneumoniae were higher than those for Europe. Our findings highlight the necessity to implement an integrated system for monitoring not only consumption of antibiotics and resistance profiles but also the clonality of alert microorganisms in the ICU for effective infection control. © 2015 Agodi et al.

It is well known that a monochromatic X-ray source with an energy optimized for the organ thickness to be imaged could result in a better image quality in transmission radiology. In this paper we present the preliminary investigation for the implementation of this technique in computer tomography (CT) imaging. The detection system is based on a 1 mm thick silicon pixel detector bump bonded to a VLSI read-out, Medipix2. This detector ensures a good detection efficiency (46%) in the used energy range (60 kVp) with a good spatial resolution that arises from a 55 μm square pixel. The Medipix2 read-out electronics is not only a single photon counting system, but has also the capability of dual-energy threshold, that allows us to detect only photons that are in a chosen energy window. In this paper we present the results obtained in CT imaging of small samples, by selecting various energy windows within a standard X-ray tube spectrum so as to maximize the differentiation between significant attenuation coefficients. This study is preliminary for a future development of a dual-energy CT that could add functional information to the morphological information that is obtained in a CT examination.

Computed Tomography (CT) gives 3-D morpho logical images of the object under test. Anatomica information from CT can be used to compensate the limits of radionuclide imaging techniques. First of al it can help in physically localizing the uptake site within the body of the animal, thus allowing the ana tomical identification of the site. The CT scan also helps in performing more accurate radionuclide quan tification studies. These are usually performed by selecting a region-of-interest on the SPECT (or PET image: the higher spatial resolution of the CT allow more precise determination of the boundary of the ROI, and therefore of the number of counts within the ROI.

Background: Infections caused by multidrug-resistant (MDR) Acinetobacter baumannii have become an important healthcare-associated problem, particularly in intensive care units (ICUs). Aim: To investigate the emergence of carbapenem- and colistin-resistant A.baumannii infections in two Sicilian hospitals. Methods: From October 2008 to May 2011, a period which included two Italian Nosocomial Infections Surveillance in ICUs network (SPIN-UTI) project surveys, all carbapenem-resistant A.baumannii isolates from the ICUs of two hospitals in Catania, Italy, were prospectively collected. Minimum inhibitory concentrations (MICs) were measured by agar dilution, and phenotypic testing for metallo-β-lactamase (MBL) production was performed. Carbapenem resistance genes and their genetic elements were identified by polymerase chain reaction and sequencing. Genotypic relatedness was assessed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. Patient-based surveillance was conducted using the SPIN-UTI protocol and previous antibiotic consumption was recorded. Findings: Twenty-six carbapenem-resistant A.baumannii were identified. Imipenem and meropenem MICs ranged from 4 to >32mg/L, and 15 isolates exhibited high-level colistin resistance (MICs >32mg/L). PFGE demonstrated that all isolates belonged to a unique clonal type and were assigned to ST2 of the international clone II. They harboured an intrinsic blaOxA-51-like carbapenemase gene, blaOxA-82, which was flanked upstream by ISAba1. Conclusions: The dissemination of clonally related isolates of carbapenem-resistant A.baumannii in two hospitals is described. Simultaneous resistance to colistin in more than half of the isolates is a problem for effective antibiotic treatment. Prior carbapenem and colistin consumption may have acted as triggering factors. © 2014 The Healthcare Infection Society.

SUMMARYThe aim of this study was to evaluate the presence of influenza virus co-infections in humans and changes in the genetic variability of A(H3N2) virus strains in southern Italy from 1999 to 2009. A partial sequence of the haemagglutinin (HA) gene by human influenza H3N2 strains identified in oropharyngeal swabs from patients with influenza-like illness was analysed by DNA sequencing and a phylogenetic analysis was performed. During the seasons 1999–2000, 2002–2003, 2004–2005 and 2008–2009, the influenza viruses circulating belonged to subtype H3N2. However, A(H1N1) subtype virus and B type were respectively prevalent during the 2000–2001, 2006–2007, 2007–2008 and 2001–2002, 2003–2004, 2005–2006 seasons. The HA sequences appeared to be closely related to the sequence of the influenza A vaccine strain. Only the 2002–2003 season was characterized by co-circulation of two viral lineages: A/New York/55/01(H3N2)-like virus of the previous season and A/Fujian/411/02(H3N2)-like virus, a new H3 variant. In this study, over the decade analysed, no significant change was seen in the sequences of the HA gene of H3 viruses isolated.

Current pulses produced by absorption of picosecond near-infrared light pulses have been used in order to analyze the shape of the electric field and charge transport properties in semi-insulating (SI) GaAs Schottky barrier X- and gamma-ray detectors. Diodes with square pads of side 0.2–1 mm on 200, 600 and 1000-μm-thick SI GaAs substrates have been illuminated from the front (Schottky) contact, from the back (ohmic) side and laterally between the contacts. Current pulses have been recorded with a fast digital sampling oscilloscope, at room temperature, without using any signal amplification. Current and charge pulse shapes have been analyzed as a function of reverse bias voltage, positioned on the detector surface and optical wavelength around the near-infrared absorption edge of GaAs. The wavelength tuning allows for increasing light penetration lengths. Signal analysis gives the peak current, total collected charge and the charge collection time, which are related to the average strength of the electric field and the drift velocity field, while pulse shape depends on the local value of these fields. The experimental results show that a complete detector characterization is feasible with this optical technique, in a manner analogous to that commonly done with gamma- or X- or alpha-ray sources, with the advantage of analyzing the charge collection time. An additional advantage is represented by focusing the light beam on the detector surface, for 1D or 2D scan.

Sepsis is a major cause of significant morbidity and mortality in neutropenic patients. Blood culture remains the gold standard in the microbiological diagnosis of bacterial or fungal bloodstream infections, but it has clear limits of rapidity and sensitivity. The objective of the study was to compare the real-time polymerase chain reaction (RT-PCR) with automated blood cultures (BC) method in detection in whole blood of pathogens in febrile neutropenic patients with hematological malignancies.A total of 166 consecutive febrile neutropenic patients were enrolled. Blood samples for cultures and SeptiFast testing were obtained at the onset of fever, before the implementation of empirical antibiotic therapy.Forty (24.1%) samples out of the 166 blood samples tested, were positive by at least one method. Twenty-three (13.9%) samples were positive by blood culture and 38 (22.9%) by multiplex real-time PCR. The analysis of concordance evidenced a low correlation between the two methods (n = 21; 52.5%), mainly due to samples found negative by culture but positive with the Septi-Fast assay. Sensitivity, specificity, and positive and negative predictive values of RT-PCR were 91.3%, 88.1%, 55.3%, and 98.4%, respectively, compared with BC.Multiplex real-time PCR assay improved detection of the most bacteria associated with febrile neutropenia episodes. Further studies are needed to assess the real advantages and clinical benefits that molecular biology tests can add in diagnosis of sepsis.

We are implementing an X-ray breast Computed Tomography (CT) system on the gantry of a dedicated single photon emission tomography system for breast Tc-99 imaging. For the breast CT system we investigated the relevance of the beam hardening artifact. We studied the use of a single photon counting silicon pixel detector (0.3 mm thick, 256 � 256 pixel, 55mm pitch, bump-bonded to the Medipix2 photon counting readout chip) as detector unit in our X-ray CT system. We evaluated the beam hardening ‘‘cupping’’ artifact using homogeneous PMMA slabs and phantoms up to 14 cm in diameter, used as uncompressed breast tissue phantoms, imaged with a tungsten anode tube at 80 kVp with 4.2 mm Al filtration. For beam hardening evaluation we used a bimodal energy model. The CT data show a ‘‘cupping’’ artifact going from 4% (4-cm thick material) to 18% (14-cm thick material). This huge artifacts is influenced by the low detection efficiency and the charge sharing effect of the silicon pixel detector. r 2007 Published by Elsevier B.V. PACS: 85.57.cp; 87.57.Q

The aim of this work is to evaluate the capability of a single photon counting acquisition system based on the Medipix2 read-out chip for Computed Tomography (CT) applications in Small Animal Imaging. We used a micro-focus X-ray source with a W anode. The detection system is based on the Medipix2 read-out chip, bump-bonded to a 1 mm thick silicon pixel detector. The read-out chip geometry is a matrix of 256×256 cells, 55 μm×55 μm each. This system in planar radiography shows a good detection efficiency (about 70%) at the anode voltage of 30 kV and a good spatial resolution (MTF=10% @ 16.8 lp/mm). Starting from these planar performances we have characterized the system for the tomography applications with phantoms. We will present the results obtained as a function of magnification with two different background medium compositions. The effect of the reconstruction algorithm on image quality will be also discussed.

In digital imaging the ability to detect low contrast details is an aim that must be pursued. In order to achieve this result we have developed an acquisition system based on silicon pixel detector. The detector is a matrix of 256×256 square pixels of 55 μm size. It is bump-bonded to a readout chip developed by the Medipix2 Collaboration [X. Llopart, et al., IEEE Trans. Nucl. Sci, NS-49 (5) (2002) 2279]. To see the low contrast details with this system, it is necessary to reduce inside the image the fluctuations of pixel-to-pixel counts, [1] down to statistical fluctuations. This has been achieved equalizing the phantom image with a high statistics flat field acquired in the same irradiation condition. We have studied the dependence of the image uniformity for different flat field and we have investigated the dependence of the image quality on the thickness of the phantom and on the energy window selected inside the incident spectrum.

Digital mammography is entering routine clinical use and many commercial systems are now in use in the radiological units for screening and diagnostic mammography. At the same time, the research in the digital mammography field is very active in the development of more and more performing devices. In this paper we present the performance of single photon counting pixel detectors (MedipixI) tailored for digital mammographic applications. These devices are based on semiconductor (Si and GaAs) pixel detectors of different thickness, read-out by custom designed integrated circuits. To assess the imaging capability of such systems, the images of a mammographic phantom have been acquired in standard conditions for a clinical examination. The signal-to-noise ratio (SNR) of details simulating tumor masses has been evaluated. The same phantom has been also radiographed by three different commercial digital mammographic systems in the same reference conditions and a comparison in terms of SNR has been carried out. The spatial resolution of the single photon counting systems has also been evaluated by measuring the line spread function with the edge technique and then calculating the Modulation Transfer Function (MTF). The MTFs of the single photon counting systems have been compared with the MTFs of the commercial systems.

In this study of influenza vaccination, 37 human immunodeficiency virus (HIV)-1-seropositive patients were randomized to receive either a vaccine with a conventional subunit or one adjuvanted with MF59. Blood samples were collected at the time of vaccination, and then 30 and 180 days later, to evaluate immunogenicity, CD4+ T-lymphocyte count and HIV-1 RNA levels. Seroconversion rates against the three viral strains included in the vaccine ranged between 44% and 72% and 53% and 68% for the adjuvanted vaccine and the subunit vaccine, respectively. Other criteria of the European Medicines Evaluation Agency were also met. Vaccination was not associated with serious adverse events. Local and systemic effects were mild and of short duration. CD4+ T-lymphocyte counts and viraemia levels were not negatively affected by vaccination. These results confirmed the safety and immunogenicity of these currently available vaccines in HIV-1-seropositive patients, thus supporting the recommendation for influenza immunization in this high-risk category.

Several INFN Sections and Departments of Physics of Italian Universities have spent many man-years in the attempt to adapt detector and read-out technologies, originally developed in the field of High Energy Physics, to the domain of biomedical apparatuses. The research covered such areas as the exploitation of crystals for the production of monochromatic X-ray beams, the development of devices for efficient X-ray detection, the design of advanced VLSI electronics, the improvement of Position Sensitive Photomultiplier Tubes and crystals for Nuclear Medicine gamma-cameras. These studies have been integrated in the Integrated Mammographic Imaging (IMI) project, funded by the Italian Government through the law 46/82 (art.10) and is carried on by five high-technology industries in Italy, namely LABEN, CAEN, AMS, GILARDONI and POL.HI.TECH. We report on the status of this technological transfer project.

The Integrated Mammographic Imaging (IMI) project aims to realize innovative instrumentations for morphological and functional mammography, in particular, one of the research topics is the design and development of a prototype of a mammographic head. Innovative industrial processes for the production of GaAs pixel detectors and for their bump-bonding to the read-out VLSI electronics have been developed by AMS. The data acquisition and processing have been developed by LABEN; the power supply and distribution system has been realized by CAEN; while the integration of the head in a standard mammograph has been carried on by the Laboratori di Ricerca Gilardoni.

Our group is working at the development of a prototype for digital mammography based on semiconductor detectors inside the “Integrated Imaging Mammographic” project, which is a collaboration between some industries and some research groups (I” and University Physics Departments of Pisa, Ferrara, Roma, Laben, AleniaMarconiSystems, CAEN, Pol.Hi.Tech., Gil ardoni). The detection unit has an active area of 1.2 cm2 and is composed by a semiconductor pixel detector and a single photon counting chip (PCC, developed within the framework of the MEDIPIX collaboration [I], [2]). The chip contains 64 x 64 square cells, 170 pm in side, connected to each pixel of the detector by bump bonding. Each cell is an asynchronous read-out channel, equipped with a low noise charge preamplifier, a latched comparator, a digital shaper and a 15 bits counter. In order to improve the detection efficiency in the energy range of mammography, we designed and simulated 300 pm and 525 pm thick Si detector, that have been produced by ITC-IRST (Trento, Italy). We have simulated the behaviour of the electric potential inside the detector in order to find a geometry to optimize the performances of our detector and to avoid the risk of breakdown that will be more likely as one will increase the thickness.

As the use of digital radiographic equipment in the morphological imaging field is becoming largely diffuse, the research of new and more performing devices from public institutions and industrial companies is in constant progress. Many of these devices are based on solid-state detectors as X-ray sensors. Semiconductor pixel detectors, originally developed in the high energy physics environment, have been then proposed as digital detector for medical imaging applications. In this paper a digital single photon counting device, based on silicon and GaAs pixel detectors, is presented. The detector is a thin slab of semiconductor crystal equipped with an array of 64 by 64 square contacts, 170-μm side. The data read-out is performed by a VLSI integrated circuit named Photon Counting Chip (PCC), developed within the MEDIPIX collaboration. Each chip cell geometrically matches the sensor pixel. It contains a charge preamplifier, a threshold comparator and a 15 bits pseudo-random counter and it is coupled to the detector by means of bump-bonding. Most important advantages of such a system, with respect to a traditional X-rays film/screen device, are the wider linear dynamic range (3x10 4 ) and the higher performance in terms of MTF and DQE. Electronics read-out performance as well as imaging capabilities of the digital device will be presented. Images of mammographic phantoms acquired with a standard mammographic tube will be compared with radiographs obtained with traditional film/screen systems.

In this work we exploit the advantages of using a bi-chromatic X-rays source coupled with a single photon counting pixel detector to perform a feasibility study for dual energy mammography. This technique allows enhancing the contrast between different breast tissues by composing two images acquired at two different energies. The high and low energy images have been acquired by a single X-ray shot. The bi-chromatic beam has been produced per diffraction of polychromatic photons by a monochromator crystal. The imaging system is based on a single photon counting silicon pixel detector. The data read-out is performed by a VLSI Integrated Circuit bump-bonded to the sensor. The energy threshold of each electronics channel can be individually trimmed. We set the threshold of one pixel below 16 keV while the threshold of the neighboring pixel between 16 and 32 keV. With a single exposure the information from both energies is recorded. After separation between low and high threshold pixels, we obtained two independent images. We acquired radiographs of phantoms made of three different materials. Appling a dual energy algorithm, we obtained synthesized images where any of the three materials is removed from the radiograph, enhancing the contrast between the two remaining.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In mammography, the first cause of image contrast reduction arises from the photons scattered inside the examined organ. The amount of Compton scattering strongly depends on the irradiation area and on the distance between the organ and the X-ray detector. We have experimentally evaluated how these geometrical conditions affect the scattering fraction. Our experimental setup includes a single photon counting device based on a silicon pixel detector as X-ray sensor; a lucite cylinder to simulate the breast tissue, and a lead collimator to define the irradiation area. We have evaluated the contrast and the signal-to-noise ratio for images acquired in different conditions.

A multiple-exposure technique in digital mammography has been developed to suppress the physical background in the image due to Compton scattering in the body. A pair of X-ray masks, shaped in a projective geometry and positioned upstream and downstream the patient, are coupled mechanically and moved in four steps along a square pattern in order to irradiate the full area in four consecutive short exposures. A proof-of-principle apparatus is under test with a breast phantom and a standard mammographic X-ray unit. Results are reported.

In this work we present the results of a systematic study about SI GaAs detectors as a function of substrate and contact type, geometry and thickness. This study has been stimulated from the interest in using GaAs as a detector for medical imaging applications. GaAs detectors have been produced using crystals grown with different techniques and changing both the thickness (in the range 200 μm-1 mm) and the contacts type and geometry. We have measured the current-voltage characteristics and, using radioactive sources (109Cd, 20 keV photons, 241Am, 60 keV photons, 99mTc, 140 keV photons), we have studied the performance of our detectors in terms of charge collection efficiency and energy resolution as a function of the bias voltage. Besides we have also studied the electrical and spectroscopic properties of GaAs detectors with different types and concentrations of the dopants in the substrate. So we have found the optimal doping type and concentration to have the best spectroscopic performances and the higher breakdown voltage. Simulation programs made with Monte Carlo methods have been developed to describe the electric field distribution and the transport of charge carriers toward the electrodes in GaAs detectors. In these simulations we have considered the presence of deep energy levels in the bandgap, the thickness, the bias voltage and the charge deposition in the crystal after photon interaction.

Semi-insulating gallium arsenide (SI-GaAs) detectors, in the form of Schottky diodes, have been irradiated from the front or from the back contact or from the side, with light pulses from picosecond laser source, tunable in the range of 780–1020 nm and focused to a 50–100 μm spot on the surface of the detector. Energy per pulse was in the range of 4–25 pJ, with a 10 or 100 Hz repetition rate. Each pulse mimics the interaction of a single energetic particle with the substrate, but with a photon mean free path modulated in the range of 1 μm–1 cm, depending on the light wavelength. The SI-GaAs substrates have a thickness of 200 μm (VGF grown), or 600 μm (LEC) or 1000 μm (VGF). The time response of the detectors, analysed with the Transient Current Technique (using a fast digital sampling oscilloscope) in terms of peak signal amplitude and charge rise time, has been evaluated as a function of: reverse voltage bias (50–1200 V), light wavelength (780–1020 nm), side position between the electrodes, position on the front contact. The results are: (1) the shape of the transient current signal may show the presence of two peaks, about 1 ns apart; (2) the charge rise time, considered to be dominated by the charge collection time, is between 2 and 13 ns; (3) the charge rise time, as due to electron drift or hole drift in the region between the contacts, has been measured as 2–5 ns, also dependent on the applied bias; (4) the transient current (exponential) decay time, for front or back irradiation, increases with the bias voltage up to 2–20 ns and these data are considered to be consistent with the electron detrapping time; (5) under reverse bias, for 1 mm pad side and a large ohmic contact on the back, the electric field extends around the front contact up to about 200 μm.

This study follows a cognitive investigation about risk factor for ischemic heart disease performed in 1990 by a group of general practitioners in Pistoia, Italy. From this investigation we selected subjects with hypercholesterolemia; we also considered the association with other risk factors for ischemic heart disease. According to the frequency of risk factors subjects received a low-fat diet or diet plus cholesterol-lowering drug therapy (simvastatin). We describe changes on total cholesterol and its fractions by these therapeutic regimens.

A serological survey was performed to determine the prevalence of antibodies against human bocavirus in an Apulian population. Anti-hBoV IgG antibodies were analysed in 1206 inhabitants (age range, 1 month–84 years) using a standardized ELISA test based on the use of recombinant hBoV VP2 virus-like particles. In total, 1075 (89.1%) of 1206 participants (mean age 32 ± 24.8 years) displayed anti-hBoV-IgG. The seroprevalence increased significantly (p < 0.0001) in children from 2–4 years (64.2%) to 5–9 years (96.4%). A similar trend was observed in both male and female subjects. In conclusion, our results show that hBoV infection is common in this population, especially in children.

Relationships between regional cerebral blood flow (rCBF) and the Luria-Nebraska Neuropsychological Battery (LNNB) were examined utilizing 15 adolescent psychiatric inpatients. Significant correlations were obtained between the gray matter measure on the rCBF and those scales on the LNNB more related to nonverbal function.

The Authors carried out a clinical study of a new benzodiazepinic derivative (Ro 5-4200) presenting hypnotic properties particularly "interesting". The results emerged from this study confirmed the hypnotic efficacy of the preparation also in case of insomnia of a certain seriousness, as well as its excellent tolerance.

Imaging capabilities, spatial resolution and spectroscopic analysis have been performed to compare the characteristics of imaging systems based on pixel detectors of different thickness. Each system consists of a single photon counting chip (PCC), developed in the framework of the Medipix Collaboration, bump bonded to a silicon detector. The detector is a matrix of 64times64 square pixels, with 170 mum pitch and thickness ranging from 300 to 800 mum. As expected, the intrinsic detection efficiency increases with detector thickness (for 22 keV photons the detection efficiency doubles in the examined thickness range), nevertheless the spatial resolution can be affected by a charge sharing mechanism between adjacent pixels due to charge diffusion. We have studied this effect and its dependence on the detector bias voltage and the threshold value of PCC with the aim of optimizing both the detection efficiency and the spatial resolution