Assessment of a high-resolution candidate detector for prostate time-of-flight positron emission tomography

We report on the measurements performed using a 22Na source on a detector element for an MRI-compatible TOF-PET endorectal prostate probe, with Depth-Of-Interaction sensitivity. It is made from a LYSO scintillator crystal, wrapped with Lumirror, readout at both ends by means of Silicon Photomultipliers. With a detailed description of the data analysis procedure we show that our results point to a 400 ps coincidence resolving time and, at the same time, to a Depth-Of-Interaction resolution of 1 mm. These appealing features, along with the tiny 1.5 mm x 1.5 mm x 10 mm crystal size, are quite promising in view of the realization of a prototype probe.Comment: 27 pages, 28 figures. arXiv admin note: substantial text overlap with arXiv:1203.004

Influence of Rotation Speed of Mtwo Files on Root Canal Instrumentation Time with Different Canal Curvatures

Introduction: The aim of this study was to analyze the effect of rotation speed on the instrumentation time of root canals with different curvatures using Mtwo NiTi rotary instruments. Methods and Materials: Forty root canals were selected and divided into 2 groups, according to the angle of curvature (group A>30°, group B<30°). Both groups were divided into 2 subgroups (n=10), according to the rotational speed used for root canal instrumentation (150 rpm: group A1 and B1; 250 rpm: group A2 and B2). The total instrumentation time and the total number of instrumentation cycles (NCI) required to complete root canal preparation were registered for each canal. The mean and standard deviation were then calculated. Data were then statistically analyzed using two-way ANOVA and interaction effect P-values (P<0.05). Results: During root canal instrumentation, there were no file fractures. Total instrumentation time of the low speed groups A1 (150 rpm) and B1 (150 rpm) were significantly higher (P<0.05) than that of the high speed groups, A2 (250 rpm) and B2 (250 rpm); however, there was no statistically significant difference in terms of NCI between the different groups (P>0.05). Statistical difference was not found between the different angles of curvature, group A1 vs B1 and A2 vs B2 in terms of total instrumentation time (P>0.05) and NCI (P>0.05). Conclusions: This ex-vivo study showed that canal preparation with Mtwo rotary files could be completed safely with an increase of the instrumentation time at low rotational speed independently of the root canal curvature

HELNED: Helium-3-free low-cost neutron detectors

We developed a technique for thermal neutron detection not making use of 3He, also suitable for online real time monitoring of CASTOR spent fuel containers. As a neutron converter we used 6LiF, being the neutron capture cross section of 6Li very well known and with only an alpha and a triton in the exit channel. We can deposit thin layers of converter onto several different substrates, to be placed on top of solid state detectors or scintillators capable of efficiently detecting the decay products

Performance evaluation of SiPMʼs for low threshold gamma detection

In the context of the on-line monitoring of short and medium term for radioactive waste repository, a new system has been planned. Such system makes use a new kind of detector, named Silicon Photomultiplier, coupled to scintillating fibres to be positioned around each waste drum in shape of fine grid. The purpose of this design is evaluate the variations of the radioactivity distribution by counting the gamma radiation

A framework for threat recognition in physical security information management

In modern society, the capability to ensure an adequate level of security to persons and infrastructures is essential for the development of a territory. Malicious acts as well as adverse natural events can pose a threat to the physical security. Whatever the application domain, the protection of complex, extended and critical environments requires the development of innovative approaches to the security. They must aim at recognizing threats scenarios as early as possible, providing superior situation awareness and decision support, in order to activate a quick and focused response. The research presented in this thesis addresses that issue, on different levels. At a methodological level, by defining a general paradigm of “augmented surveillance”, thanks to information fusion strategies. At the application level, by developing a framework aimed at the automatic and early detection of threat scenarios, thanks to a model-based logical, spatial and temporal correlation of events. In order to improve the detection effectiveness and efficiency, the work introduces a heuristic situation recognition, based on ad-hoc distance metrics; and a real-time trustworthiness evaluation of the detected threat scenarios, based on uncertainty parameters characterizing sensors and models. Finally the thesis includes the application of those techniques to railway and mass-transit domain and the overall integration of the framework with an existing PSIM system