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The GAP multidisciplinary study carried out in South London, recruited 410 first episode of psychosis patients and 370 controls; the aim was to elucidate the multiple genetic and environmental factors influencing the onset and outcome of psychosis. The study demonstrated the risk increasing effect of adversity in childhood (especially parental loss, abuse, and bullying) on onset of psychosis especially positive symptoms. Adverse life events more proximal to onset, being from an ethnic minority, and cannabis use also played important roles; indeed, one quarter of new cases of psychosis could be attributed to use of high potency cannabis. The “jumping to conclusions” bias appeared to mediate the effect of lower IQ on vulnerability to psychosis. We confirmed that environmental factors operate on the background of polygenic risk, and that genetic and environment act together to push individuals over the threshold for manifesting the clinical disorder. The study demonstrated how biological pathways involved in the stress response (HPA axis and immune system) provide important mechanisms linking social risk factors to the development of psychotic symptoms. Further evidence implicating an immune/inflammatory component to psychosis came from our finding of complement dysregulation in FEP. Patients also showed an upregulation of the antimicrobial alpha-defensins, as well as differences in expression patterns of genes involved in NF-κB signaling and Cytokine Production. Being of African origin not only increased risk of onset but also of a more difficult course of illness. The malign effect of childhood adversity predicted a poorer outcome as did continued use of high potency cannabis.

Ailanthus altissima is an extremely aggressive and globally invasive species. This tree has ideal growing conditions in ruderal areas, and is difficult to manage, as cutting is a trigger for the sprouting of new suckers. Despite the wide literature on the negative impacts of this species, measurements of its interaction with archaeological monuments are lacking. We analyzed its colonization behavior and the caused damages along the Aurelian Walls in Rome, which resulted in detachments, crackings and deformation. Our results highlighted the rapid growth potential and wide distribution of this tree in the site (48 nuclei with 578 stems, mainly root suckers, along 7.1 km of 12.5 total length). Our study also provides a quantitative assessment of the damaging potential of A. altissima, as, in 16 out of 48 nuclei, we detected visible damage to the walls, which were likely due to both mechanical and chemical interactions through acidic exudates. The damages correlated significantly with plant size but not with plant distance from the walls, likely due to the wide lateral spread of the roots. This work highlighted the need to monitor and contain A. altissima, but also offers a general approach for the assessment of risks to monuments by higher plants.

The Hamamatsu H8500 Flat Panel PMT is the latest technological advancement in gamma ray imaging. Its compact size makes it attractive for medical imaging applications. To study and compare image performance a Flat Panel PMT, representing the present production, was coupled to CsI(Tl) and Nal(Tl) scintillation arrays with 3 mm and 1.8 mm pixel size respectively and connected to a multi-anode electronic readout. Furthermore, a pulsed blue LED coupled to an optical liber was utilized to scan the tube with different light distributions. This study investigated how PMT anode gain uniformity response, scintillation light distribution and intensity influence the spatial resolution, the position linearity and the image noise. Each crystal in the scintillation array produces a different charge distribution, which depends on the match between the anode size and the scintillation array lattice. The Nal(Tl) array demonstrated to fit both PMT characteristics and dynamic range of electronic read out, due to the charge distribution adequate to the anode size. For CsI(Tl) crystal, the pulse height calibration resulted more critical, due to the narrow light distribution. In conclusion, the use of Flat Panel tube with selected anode gain uniformity could represent the cheapest and easiest solution to obtain the best image quality, in particular for scintillator array with smaller pixel size.

This paper reports on design, fabrication and characterization of a micro-filter for hearing aid, dialysis media and inhaler. The microfilter is fabricated by micro injection moulding process in polymeric material (Polyoxymethilene - POM) using a steel mould manufactured by micro electrical discharge machining process. A novel filter configuration is proposed and, in the design step, the characteristics of the filter are investigated by numerical simulation in order to define a suitable geometry for micro-injection moulding. Then, different process configuration of parameters (melt and mould temperature, injection velocity, holding time and pressure, cooling time, pressure limit) are tested in order to obtain the complete part filling. Finally the component is dimensionally characterized and the process parameters optimized to obtain the maximum filtration capacity.

In injection moulding, continuous monitoring of temperature and pressure parameters in the mould cavity is very important for process control and optimization. In the micro injection moulding process, however, it is more difficult to measure the cavity pressure and temperature due to the extremely small sizes involved. In this paper, a novel setup for cavity pressure and temperature measurements is presented: a miniaturized p,T quartz sensor is used to measure both pressure and temperature directly in the middle of the mould cavity and a data acquisition system has been developed in order to collect signals provided by the sensors. It was demonstrated the suitability of the novel setup to micro injection moulding and that it can be easily applied to any micro injection moulding machine.

Over the last ten years the strong technological advances in position sensitive detectors have encouraged the scientific community to develop dedicated imagers for new diagnostic techniques in the field of isotope functional imaging. The main feature of the new detectors is the compactness that allows suitable detection geometry fitting the body anatomy. Position sensitive photomultiplier tubes (PSPMTs) have been showing very good features with continuous improvement. In 1997 a novel gamma camera was proposed based on a closely packed array of second generation 1 in PSPMTs. The main advantage is the potentially unlimited detection area but with the disadvantage of a relatively large non-active area (30%). The Hamamatsu H8500 Flat Panel PMT represents the last generation of PSPMT. Its extreme compactness allows array assembly with an improved effective area up to 97%. This paper, evaluates the potential improvement of imaging performances of a gamma camera based on the new PSPMT, compared with the two previous generation PSPMTs. To this aim the factors affecting the gamma camera final response, like PSPMT gain anode variation and position resolution, are analyzed and related to the uniformity counting response, energy resolution, position linearity, detection efficiency and intrinsic spatial resolution. The results show that uniformity of pulse height response seems to be the main parameter that provides the best imaging performances. Furthermore an extreme identification of pixels seems to be not effective to a full correction of image uniformity counting and gain response. However, considering the present technological limits, Flat Panel PSPMTs could be the best trade off between gamma camera imaging performances, compactness and large detection area.

Over the last 15 years Hamamatsu has been developed two generations of Position Sensitive Photomultipliers (PSPMTs). The first and the second generation were based on mesh dynode and metal channel dynode respectively. In this paper, we present the first results obtained from the last generation: Hamamatsu H8500 Flat Panel PSPMT. The active area is increased to 2 in. with minimum peripheral dead zone and thickness down to 12.5 mm. Measurements were addressed to nuclear medicine for single photon imaging. To this aim, we have taken into account two different electronic readout: resistive chain and multi-anode readout (64 channels). To evaluate the imaging performance, the Flat Panel PSPMT was coupled to CsI(Tl) and NaI(Tl) scintillation arrays with pixel size of 3 and 2 mm, respectively. Images of CsI(Tl) array, obtained by multi-anode readout, showed an improvement of spatial resolution, from 1.2 to 0.8 mm, and of position linearity response. On the contrary for NaI(Tl) array, no relevant image differences between two system readout were obtained.

Over the last years Nuclear Medicine and Oncology require the development of new scintigraphic imagers dedicated to particular organs and lesions, with improved performances with respect to presently available devices. In order to enhance the imaging responses, pixellated crystals have to be employed as scintillating devices coupled to position sensitive photomultiplier tubes. Some of major steps forward in this field could be obtained by using the recently produced Hamamatsu photomultiplier tubes. The knowledge of the pixel scintillation light distribution at photocathode allows the imaging performances optimization. To this aim CsI(Tl) arrays pixel light distributions were investigated by using a photographic method and a Hamamatsu multianode 16 channel linear array photomultiplier tube for single-event light output readout. Ten scintillating arrays, with square pixel base area ranging between 1.0×1.0 and 2.0×2.0 mm 2 and thickness from 1.0 to 5.0 mm, were tested. In this study, the strip scintillation light distribution spread at photocathode was found linearly dependent on the total light guide thickness and crystal-pixel base side.

Due to the sensitive nature of applications of the micro injection moulding process, such as medical and aerospace, achieving high quality parts with high dimensional accuracy is crucial. In this work, simulation and an experimental study was performed to analyse the effect of four main parameters (melt and mould temperature, injection speed and holding pressure) on dimensional accuracy of a micro feature. Moreover, the focus was also to assess the process capability of a screwless/two plungers micro moulding machine in processing polyoximethilene (POM) and liquid crystal polymers (LCP). Results showed that mould temperature and injection speed was the most effective on dimensional accuracy respectively for POM and LCP and high settings for all the parameters improved the accuracy of the ribs. For LCP achieving process reproducibility was more difficult than POM even if the obtained dimensional errors are considerably lower.

Mammoscintigraphy is an important tool for secondary breast cancer screening. Good results have been achieved with dedicated gamma cameras for T 1b tumors (size >5 mm). We have performed simulations and measurements in order to improve the performance of compact gamma cameras for detecting T 1a tumors (size 3 ) coupled with a Position Sensitive Photomultiplier Tube (PSPMT) having a multianode structure (2×2 mm 2 pad size). Measurements allowed to test the validity of the simulation software.

The new PMT generation with very high quantum efficiency is very attractive for their potential to improve energy resolution, in particular for applications involving new scintillation crystals with high light yield. Furthermore recent development of new devices, like silicon photomultipliers (SiPMs), with high gain and quantum efficiency have raised the competition between silicon and standard photomultiplier device in particular for application where high energy resolution may improve the imaging response of the detector. Hamamatsu has recently developed a new prototype PMT R7600-200 with an Ultra BiAlkali (UBA) photocathode (QE=42%). To evaluate the improvement, we compared the energy resolution obtained by R7600-200 PMT with ones from a standard R7600 PMT (QE=22%); the results from both PMTs was obtained with a standard and a tapered divider circuit respectively. We compared also the data from a MA-PMT H8500 and from a PMT R6231, representing a gold standard. A LaBr3:Ce scintillator crystal (½” diam. x ½” thick) was coupled to all PMTs. Preliminary results show an energy resolution improvement with UBA photocathode of about 30% @122keV with respect to R7600, close to what expected from the higher quantum efficiency (40%). On the contrary they agree with ones from R6231 PMT, thought its lower QE. This result is probably due to the different collection efficiency of first dynode stage related to different dynode structure of tubes. Furthermore an energy resolution improvement smaller than expected resulted from H8500 MA-PMT. Thought the same dynode structure, this result is not well understood and it could probably due to the larger size of MAPMT photocathode, involving a better light collection. In any case, the improvement of 30% between UBA e No-UBA PMT is not in agreement with the expected one (20%), considering the intrinsic energy resolution of LaBr3:Ce (4.4%@ 140 keV). This behavior is not well explained at moment and is matter of next investigations.

The availability of LaBr3:Ce crystals from St. Gobain has started various investigations in the field of medical imaging, in particular in PET, SPECT and Compton camera systems. At present LaBr3:Ce crystals are available in a continuous shape covering up to 10×10 cm2 with a thickness of 1 cm, in contrast, serious concerns are arising in pixellated manufacturing. With the aim of verifying the potentials introduced by LaBr3:Ce for SPET imaging, two small γ cameras based on Anger camera principle have been assembled and imaging performances were compared. Two crystals of LaBr3:Ce and NaI(Tl) with the same detection area (5×5 cm2) and thickness of 5 and 1.5 mm, respectively were been integrally assembled with a H8500 Hamamatsu flat panel PMT. Through the thicker crystal, the LaBr3:Ce camera showed superior imaging and detection performances at 140 keV compared with the NaI(Tl) one, with 0.9 mm FWHM intrinsic spatial resolution, 8% FWHM energy resolution and 80% intrinsic detection efficiency.

Over the last three years, there has been a growing interest in the development of a new class of fast scintillators such as LaCl3 :Ce and LaBr3:Ce, or their superior energy resolution is opening an easier way to improve spatial resolution. In this paper we present the results obtained from the first LaBr3:Ce small gamma camera. It is based on continuous 50 times 50 mm2 crystal 5 mm thick integral assembled with a Hamamatsu Flat panel PMT. This detector optical configuration permits the narrowest light distribution and highest light collection to obtain the best spatial and energy resolution values respectively. At the same time 5 mm crystal thickness carries out 80% efficiency at 140 keV photon energy. Measurements of spatial resolution are also compared with the analogous ones obtained from another 50 times 50 mm2 LaBr3:Ce crystal, assembled with a 3 mm glass optical window. Energy resolution values have been furtherly compared with ones obtained from a LaBr3:Ce one inch diameter and thickness optimized for spectrometric measurements. The first LaBr3:Ce gamma camera shows excellent intrinsic spatial resolution values such as 0.9 mm with a best energy resolution value of 6.0% at 140 keV photon energy

Micro components and micro devices are strongly used in several fields: IT components, biomedical and medical products, automotive industry, telecommunication area and aerospace. A micro component is characterized by small dimensions of the product itself or small dimensions of the functional features. The development of new micro parts is highly dependent on manufacturing systems that can reliably and economically produce micro components in large quantities. In this context, micro-electrical discharge machining (EDM) for mould production and micro-injection moulding of polymer materials are the key technologies for micro manufacturing. This paper will focus on the production and quality evaluation of polymeric micro components manufactured by micro injection moulding. In particular the authors want to investigate the process parameters on the overall quality of the product. The factors affecting micro flow behavior, components weights and dimension definition are experimentally studied basing on DoE approach and then discussed.

Since traditional handling mechanisms have an unpredictable behavior at micro scale, micro‐assembly is a bottleneck in the development of hybrid micro‐systems, and the development of new approaches is strongly demanded. In this paper, a recent study of the fabrication of a ceramics vacuum micro‐gripper to handle parts in the range of hundreds of microns (300–1000) is presented. Among the possible micro manufacturing processes, micro‐EDM has been selected as proving to be a very competitive fabrication technology for the manufacturing of ultra miniature components and micro sized features. The influence of the process parameters on the machining performance of interest is firstly investigated; then, the experimental results on machining the micro gripper are presented, finally concluding remarks are given.

Dextran nanobubbles were prepared with a dextran shell and a perfluoropentan core in which oxygen was stored. To increase the stability polyvinylpirrolidone was also added to the formulation as stabilizing agent. Rhodamine B was used as fluorescent marker to obtain fluorescent nanobubbles. The nanobubble formulations showed sizes of about 500 nm, a negative surface charge and a good capacity of loading oxygen, no hemolytic activity or toxic effect on cell lines. The fluorescent labelled nanobubbles could be internalized in Vero cells. Oxygen-filled nanobubbles were able to release oxygen in different hypoxic solutions at different time after their preparation in in vitro experiments. The oxygen release kinetics could be enhanced after nanobubble insonation with ultrasound at 2.5 MHz. The oxygen-filled nanobubble formulations might be proposed for therapeutic applications in various diseases.

Atrial fibrillation is the most common sustained rhythm disturbance and its prevalence is increasing worldwide due to the progressive aging of the population. Current guidelines clearly depict the gold standard management of acute symptomatic atrial fibrillation but the best-long term approach for first or recurrent atrial fibrillation is still debated with regard to quality of life, risk of new hospitalizations, and possible disabling complications, such as thromboembolic stroke, major bleeds and death. Some authors propose that regaining sinus rhythm in all cases, thus re-establishing a physiologic cardiac function not requiring a prolonged antithrombotic therapy, avoids the threat of intracranial or extracranial haemorrhages due to Vitamin K antagonists or aspirin. On the contrary, advocates of a rate control approach with an accurate antithrombotic prophylaxis propose that such a strategy may avoid the risk of cardiovascular and non cardiovascular side effects related to antiarrhythmic drugs. This review aims to explore the state of our knowledge in order to summarize evidences and issues that need to be furthermore clarified.

Over the last three years, there is a growing interest in the development of a new class of fast scintillators like LaCl/sub 3/:Ce and LaBr/sub 3/:Ce. The new scintillation crystals for the first time, have the main characteristic in producing a light photon number higher than NaI(Tl) at a wavelength suited for the photocathode. The most important characteristic of these crystals is represented from the scintillation light to be yield proportionality as a function of incident gamma ray energy. With the aim to investigate on their potential in single photon imaging three one inch square LaCl/sub 3/:Ce continuous scintillation crystals with 3 and 6 mm thickness were specifically designed for position measurements. They have been coupled to a flat panel PMT through a 3 mm thickness glass window. In order to highlight all the characteristics of the detection system the third one, 3 mm thick, was integral assembled with a one inch PSPMT Hamamatsu R5900-C8. Free and collimated point radioactive sources were used for energy resolution measurements as well for scanning crystals to investigate spatial resolution and position response. Energy resolution values were compared with ones obtained from a sample of LaBr/sub 3/:Ce with one inch diameter and one thickness designed for spectrometric measurements. LaCl/sub 3/:Ce with 3 mm thickness shown energy resolution values worse than expected (13% at 140 KeV) due to the sub-optimal size and configuration for light collection. On the contrary LaBr/sub 3/:Ce carried out 6% relative energy resolution at 140 keV. Intrinsic spatial resolution values of 1 mm and 1.3 mm were obtained from 3 mm thickness LaCl/sub 3/:Ce crystals in the two configurations investigated.

SPECT and PET need a good pixel identification to obtain high quality images. This is why new generations of PSPMT with anode array with smaller step have been developed till the recent flat panel PMT H9500 with 2" square area, 256 anodes array, 3 mm individual pitch. The realization of electronic chains with so high number channels demands dedicated electronics readout with high cost and high management difficulty. In this work we propose a new method of anode number reduction in parallel readout limiting the total chain number to 64. Starting from the evidence that event charge distribution is always contained inside a portion of the FP PMT anodic plane, we assume that only a quarter of the anodes are involved in the detection. Our approach consists on virtually dividing 16times16 anodes in 4 arrays with 64 anodes per each. Once the charge distribution is collected by the 4 anodic planes, each individual anodic charge is projected on one plane. Physically, each i,j-element of one quadrant is associated to the corresponding i,j-element of the other three matrices. In terms of hardware, it is simply realized connecting one to each other the set of four i,j-anodes of the 4 quadrants. In this work an image reconstruction software has been developed and tested by measured charge distribution collected by 256 anodes Hamamatsu FP PMT. The final results, in term of spatial resolution and position linearity, are in agreement with ones collected by the total number of anodes

Hamamatsu H8500 Flat Panel PMT represents the last technological advancement in gamma ray imaging. Compact size makes it attractive for medical imaging application. To study and compare image performance two Flat Panel PMTs were coupled to CsI(Tl) and NaI(Tl) scintillation arrays with 3 mm and 1.8 mm pixel size respectively and they were connected to multi-anode electronic readout (64 channel). Furthermore a pulsed blue LED coupled to an optical fiber was utilized to scan the tube with different light distribution spreading. The study took into account how PMT anode gain uniformity response, light distribution and intensity, influence spatial resolution, position linearity and image noise. Gain calibration was firstly studied because of PMT gain anode non uniformity response, which range between 27:100 and between 45:100 respectively. Furthermore each crystal pixel produces different charge distribution and this depends on the matching between anode and scintillation array lattice. The amount of anode charge can change more than a factor five for narrow light distributions. Tube gain setting results critical, in fact because of energy resolution of each anode spectra, only a factor five pulse height variation can be adequately converted by ADC. In addition there is a further gain anode variation due to PMT non uniformity response of a factor 3. This mentioned two elements, do not allow to convert all pulses in the useful pulse height ADC range. As a consequence image position distortion and background are produced. Flat Panel shows good image performance. However, because of the big anode size and PMT gain non uniformity response, the gain setting can be critical to obtain the best image performance for scintillation light distribution comparable with anode size.

This paper is focused on the discrete scintillation imaging devices, consisting of crystal arrays and metal-channel dynode Hamamatsu 1" and 2" square position sensitive photomultiplier tubes (PSPMTs). These devices are suitable for nuclear medicine based high resolution applications, and, particularly, for single photon emission computed tomography (SPECT). The model of scintillation light distribution (SLD) previously developed was able to distinguish the responses from crystal-pixels with different side, but it was not detailed enough to explain the influence of crystal-thickness. For this reason the experimental data were reviewed to find a new and more adequate analytical model. The improved SLD model explains the influence both of crystal-side and crystal-thickness on the scintillation light-output spread. The SLD expression is quite simple and its spread depends only on one q-parameter. This expression is well adaptable over the range of examined crystal arrays. Furthermore, in the considered experiments, the SLD q-parameter was found linearly dependent on crystal-pixel shape factor S/V(S=blind-surfacearea,V=volume). An overview of discrete scintillation imager simulator (DISIS) computer code is reported. Major outcomes of this work are: 1) the improved expression of SLD, which consolidates the DISIS performances, and 2) a tool for local SLD-spread control in the imager field of view (FOV).

In recent years there has been a growing interest in developing compact gamma cameras to improve gamma ray imaging for application in nuclear medicine as well as in astrophysics, radiation physics and high energy physics. The gamma cameras based on position sensitive photomultipliers could be the best chance to obtain a realistic and low cost compact gamma camera. Since 1985 the development of position sensitive photo multiplier tubes (PSPMT) has shown the highest rate in technological advancement achieving very compact size (25 × 25 × 20 mm3) by a novel charge multiplication system. The PSPMT shows the same advantages of a standard gamma camera with the additional possibility to utilize scintillation arrays with pixel dimension less than 1 mm, thus achieving sub-millimeter spatial resolution values. The last technological advance is a PSPMT with Flat Panel structure, named H8500. Its dimension is 50 × 50 mm2 with a narrow peripheral dead zone to place closely different modules achieving large detection areas. In this paper the technological development of different PSPMT generations is reviewed and some measurements of the first Flat Panel PMT prototype are presented and compared with ones from previous generation. Flat Panel PMT could be the best trade-off between compactness, large detection areas, effective area (packing density) and imaging performance.

This paper is focused on discrete scintillation imaging devices, made by using crystal arrays and metal-channel dynode Hamamatsu 1" and 2" square position sensitive photomultiplier tubes (PSPMT). These devices are particularly suitable for nuclear medicine based high-resolution Single Photon Emission Computed Tomography (SPECT) applications. A more adequate analytical model describing the light-output spread from a single crystal-pixel, was studied. Previously experimental data published by us were reviewed using this model. The parameter which describes the intrinsic pixel light-output spread was obtained using a 1D model-version, that adequately fits the measured single-event charge-strip integrals. Furthermore the intrinsic spread was found linearly dependent, in the examined experiments, on a crystal-pixel shape factor (defined as the ratio between the pixel-blind-surface-area to the pixel-volume). Finally, a simulation tool was developed on these basis, to predict and to optimize the imager response by evaluating the impact of each device component on the response.

Over the last ten years there was being a strong advancement in photodetection. Different application fields are involved in their use in particular high energy physics, astrophysics and nuclear medicine. They usually work by coupling a scintillation crystal and more recent scintillation arrays with pixel size as small as 0.5 mm. PSPMT represents today the most ready technology for photodetection with large detection areas and very high spatial resolution. Flat panel PMT represents the last technological advancement. Its dimension is 50x50 mm 2 with a narrow peripheral dead zone (0.5 mm final goal). Its compactness allow to assemble different modules closely packed, achieving large detection areas with an effective active area of 97%. In this paper we analyze the imaging performances of PSPMT by coupling two scintillation arrays and by light spot scanning of photocathode to evaluate the linearity position response, spatial resolution and uniformity gain response as a function of light distribution spread and the number of photoelectrons generated on photocathode. The results point out a very narrow PMT intrinsic charge spread and low cross-talk between anodes. Energy resolution and spatial resolution show a good linearity with DRF variation. An unexpected intra-anode gain variation is carried out. In this paper we present the results obtained with this PSPMT regarding imaging performances principally addressed to nuclear medicine application.

The first position sensitive PMT, Hamamatsu R2486, developed in 1985, represented a strong technological advance for gamma-ray imaging. Hamamatsu H8500 Flat Panel PMT is the last generation position sensitive PMT: extremely compact with 2 in. active area. Its main features are: minimum peripheral dead zone (1 mm ) and height of 12 mm . It was designed to be assembled in array to cover large detection area. It can represent a technical revolution for many applications in the field of gamma-ray imaging as for example nuclear medicine. This tube is based on metal channel dynode for charge multiplication and 8×8 anodes for charge collection and position calculation. In this paper we present a preliminary evaluation of the imaging performances addressed to nuclear medicine application. To this aim we have taken into account two different electronic readouts: resistive chain with Anger Camera principle and multianode readout. Flat panel PMT was coupled to CsI(Tl) and NaI(Tl) scintillation arrays. The results were also compared with the first generation PSPMT.

The initial characterization results of detector modules allow one to foresee that the single photon compact ring tomograph for high resolution breast imaging can be a promising technique as well as having the exciting potential to make a real contribution to the field of breast imaging. This project is a part of larger research project including simultaneous transmission and emission tomography. Finally, this tomographic system can have a relevance which extends beyond the field of breast imaging to other areas of nuclear medicine imaging as well as the more general scope of nuclear radiation detection.

The use of position sensitive photomultiplier tubes (PSPMT) in Nuclear Medicine imaging has recently produced some major steps forward in this field. In fact a dedicated camera for the organ under examination can improve imaging performances. However, in order to maximize them, scintillating crystals arrays have to be employed. In this work 13 Csl(Tl), Csl(Na), Nal(Tl), YAP(Ce) arrays were tested. Square pixel active area ranged between 1×1 and 2×2 mm 2 and thickness from 1 to 10 mm. Light output and energy resolution responses versus photon energy and pixel thickness were measured using a standard bialkali PMT. Scintillation light spatial distribution were analyzed coupling Csl(Tl) arrays to a recently available multianode 16 channel linear array PMT. Light output study shown that Csl(Tl) is the best considered material, optimizing optical, mechanical requirements and costs. Light output as well as energy resolution resulted independent on pixel area, but strongly dependent on thickness. Csl(Tl), 1 mm thick, gave the best energy resolution values (13–14% FWHM, at 122 keV). The light output aperture angle as well as spatial resolution values resulted roughly independent on crystal geometry. The light spread resulted slightly affected by crystal pixel size. Measurements allow to foresee imaging performances of many PSPMTs coupled to the investigated arrays and give a good set of data for simulations comparison.

The design of high resolution compact gamma cameras requires careful choice of scintillation crystal and photo-detector as well as their degree of pixellation. In this paper we evaluate the imaging properties of photo detectors for clinical imaging application. We compare the performances of two kinds of scintillators (CsI(Tl) and NaI(Tl)) coupled to PSPMT's of the Hamamatsu R5900 family (C8, C12, M16 and M64). To compare the imaging properties, the PSPMT's were optically coupled to CsI(Tl) and NaI (TI) scintillating arrays with pixel size of 2 /spl times/ 2 mm/sup 2/. Spatial resolution as well as energy resolution have been measured.

Hamamatsu Photonics has recently developed a new generation of compact Position Sensitive PhotoMultiplier Tubes (PSPMT) based on metal channel dynode charge multiplication technology. R5900 family has now a range of compact tubes mainly differing for the anode structure. The models considered here, C8 and M16, also differ for active photocathode area. C8 has a crossed plate anode configuration consisting of 4X+4Y stripes and a larger active area (22/spl times/22 mm/sup 2/) while M16 has a 4/spl times/4 anode array with an active area of 18/spl times/18 mm/sup 2/. Here, the authors report their evaluation of C8 and M16 for clinical imaging applications as hand held probe, multi-PSPMT camera and tomographic ring. To this aim measurements of pulse linearity, positioning response, inter-channel gain variation and anodes cross talk were performed using a light source coupled to a 1 mm diameter optical fiber. Finally PSPMTs were optically coupled to 5 CsI(Tl) scintillating arrays with pixel size ranging between 1.5/spl times/1.5 mm/sup 2/ and 4.2/spl times/4.2 mm/sup 2/ to compare the imaging properties.

Gamma ray imaging is usually accomplished by the use of a relatively large scintillating crystal coupled to either a number of photomultipliers (PMTs) (Anger Camera) or to a single large Position Sensitive PMT (PSPMT). Recently the development of new diagnostic techniques, such as scintimammography and radio-guided surgery, have highlighted a number of significant limitations of the Anger camera in such imaging procedures. In this paper a dedicated gamma camera is proposed for clinical applications with the aim of improving image quality by utilizing detectors with an appropriate size and shape for the part of the body under examination. This novel scintillation camera is based upon an array of PSPMTs (Hamamatsu R5900-C8). The basic concept of this camera is identical to the Anger Camera with the exception of the substitution of PSPMTs for the PMTs. In this configuration it is possible to use the high resolution of the PSPMTs and still correctly position events lying between PSPMTs. In this work the test configuration is a 2 by 2 array of PSPMTs. Some advantages of this camera are: spatial resolution less than 2 mm FWHM, good linearity, thickness less than 3 cm, light weight, lower cost than equivalent area PSPMT, large detection area when coupled to scintillating arrays, small dead boundary zone (

This work presents preliminary measurements taken with the first prototype Hamamatsu (R6970) 8-inch Position Sensitive Photomultiplier Tube (PSPMT). These measurements are compared with similar ones obtained using a 5 inch PSPMT (Hamamatsu R3292). The new 8 inch PSPMT has 12 dynode stages, 11 with a proximity mesh structure whilst the last one is a back reflector. The entrance window is 7.5 mm thick and has an active area of 180 mm diameter. The crossed-wire anode of the 8 inch tube consists of 36/spl times/36 wires on a 4 mm pitch. These are paired together to give an 18/spl times/18 wire outputs. Both PSPMTs were coupled to a 110 mm diameter, 3 mm thick CsI(Tl) scintillating array in which each pixel has dimensions of 2/spl times/2 mm/sup 2/. Two read-out methods are compared in this paper. The first being the conventional resistive-divider technique. The second method uses a new multi-wire readout technique in which, the charge on each anode wire is individually read out and digitized. Measurements of the spatial resolution, position linearity, energy resolution and intrinsic charge distribution were carried out for both tubes using both read-out systems. Spatial resolution values of approximately 2 mm FWHM were obtained using the 8-inch PSPMT and the multiwire read-out technique. The other measured characteristics were similar to those obtained using the 5-inch PSPMT. These results obtained using the prototype 8-inch PSPMT underline the potential of this detector in the field of imaging in Nuclear Medicine.

The usefulness and indications to treatment with sealants in pedodontics are examined. Sealants are classified and the action mechanism of sealant resins and the application techniques needed for correct positioning of the material are described. The use of the new glass-ionomer cement sealants, with their advantages and disadvantages, are then discussed and the preventive and economic value of occlusive seals evaluated.

Prone scintimammography with Tc-99m MIBI has been proposed as a method of detecting breast cancers in women with dense breasts. Clinical reports have shown that this technique lacks sensitivity and specificity for cancers smaller than one cm. This shortcoming is unfortunate, since a patient's prognosis is most favorable when her cancer is discovered at an early stage (i.e., when the cancer is less than one cm in size). The authors explored some of the possible causes for the poor performance of prone scintimammography in this population by performing phantom and clinical studies with several different instruments, including a general-purpose gamma camera, a nonimaging germanium detector with excellent energy resolution, and a dedicated high spatial resolution camera for scintimammography (single photon emission mammography, or SPEM) using breast compression. The authors' results suggest that unlike X-ray mammography, scatter from extramammary sources plays an important role in breast imaging with radiotracers, and is the dominant effect when imaging near the chest wall. Away from the chest wall, and in conjunction with gentle breast compression (depth less than 7 cm), the energy resolution attained with a dedicated SPEM camera employing cesium iodide crystals appears adequate to differentiate between photopeak and Compton counts, with a Compton-to-photopeak ratio of less than six. The authors' preliminary clinical studies suggest that breast compression, good energy resolution and spatial resolution may improve detection of small cancers.

Recently the application of small imagers in nuclear medicine is growing, particularly in scintimammography. In this paper we propose the use of the Hamamatsu R7600-C8 Position Sensitive Photomultiplier Tube (PSPMT) for detection image optimization in scintimammography through the evaluation of image performances of detector pixellation and its interaction with a collimator lattice . To this aim, a number of CsI(Tl) scintillating arrays with different pixel size and thickness were coupled to the same PSPMT. Considering the very high intrinsic spatial resolution, a look up table was realized to correct accurately the gain non uniformities. The results show an overall energy resolution FWHM, from flood field irradiation source, in close agreement with the individual crystal response and an uniformity response within ± 10%. Finally an analysis of tumor signal to noise ratio (SNR) as a function of detection pixellation was performed, utilizing a breast phantom. Tumor SNR values are highest for 5 mm thick CsI(Tl) arrays but shown slight differences with pixel size. The best tumor SNR value for 6 cm breast thick was obtained with 1.5 × 1.5 mm2 crystal pixel size. The collimator used was a low energy all purpose, parallel hole collimator with 22 mm length, 1.5 mm hexagonal hole, 0.2 mm Pb septa, currently utilized in scintimammography.

The psychological characteristics play a key role in the development of Sport Talents (ST). The purpose of this study was to investigate the motivational orientations and psychobiosocial states in young Italian ST, by analyzing athletes of different sport, age and gender. Participants were 123 young athletes (71 Males; 52 Females, 49 aged 13-14y and 74 aged 15-17y from Emilia-Romagna, Italy, practicing the following sports. [ENDURANCE (EN): Cycling n=12, Canoe n=12, Swimming n=7, Pentathlon n=9, Cross-Country-Skiing n=7, Triathlon n=9; SITUATIONAL (SIT): Basketball n=6, Volleyball n=8, Handball n=7, Hockey n=4, Tennis n=8, Alpine-Skiing n=1), TECHNICAL AND STRENGTH-POWER (TSP): Track&Field n=19, Sport-Dance n=8, Figure-Skating n=6)]. Athletes completed the Task and Ego Orientation Self Questionnaire (TEOSQ) and a Psychobiosocial Questionnaire (PBS), in order to assess the motivational orientations and psychobiosocial states respectively. Significant differences were detected in the Ego orientation score between genders (p=0.034), and between EN and both SIT and TSP (p30) were obtained by males competing in Triathlon, Cycling, Canoe and Figure Skating, while the highest values (>23) among females were recorded in Swimmers, Triathletes and Volleyball players. Volleyball and Basketball players and Hockey and Tennis players showed the lowest values among males (36), significantly different from the lowest, represented by Pentathlon, Basketball and Handball (