A multi-layer edge-on single photon counting silicon microstrip detector for innovative techniques in diagnostic radiology

A three-layer detector prototype, obtained by stacking three edge-on single photon counting silicon microstrip detectors, has been developed and widely tested. This was done in the framework of the Synchrotron Radiation for Medical Physics/Frontier Radiology (SYRMEP/FRONTRAD) collaboration activities, whose aim is to improve the quality of mammographic examinations operating both on the source and on the detector side. The active surface of the device has been fully characterized making use of an edge-scanning technique and of a well-collimated laminar synchrotron radiation beam. The obtained data (interlayer distances, channel correspondence, etc.) have then been used to combine information coming from each detector layer, without causing any loss in spatial and contrast resolution of the device. Contrast and spatial resolution have also been separately evaluated for each detector layer. Moreover, imaging techniques (phase contrast, refraction, and scatter imaging), resulting in an increased visibility of low absorbing details, have been implemented, and their effectiveness has been tested on a biological sample. Finally, the possibility of simultaneously acquiring different kind of images with the different detector layers is discussed. This would result in maximizing the information extracted from the sample, while at the same time the high absorption efficiency of the detector device would allow a low dose delivery

Environmental Impact of Meals: How Big Is the Carbon Footprint in the School Canteens?

The inhabitants of the world are expected to grow by two billion in the next two decades; as population increases, food demand rises too, leading to more intensive resource exploitation and greater negative externalities related to food production. In this paper the environmental impact of meals provided in school canteens are analysed through the Life Cycle Assessment methodology, in order to evaluate the GHGs emissions released by food production. Meals, and not just individual foods, have been considered so as to include in the analysis the nutritional aspects on which meals are based. Results shows that meat, fish and dairy products are the most impacting in terms of greenhouse gas emissions, with values that shift from 31.7 and 24.1 kg CO2 eq for butter and veal, to 2.37 kg CO2 eq for the octopus, while vegetables, legumes, fruit and cereals are less carbon intensive (average of 3.71 kg CO2 eq for the considered vegetables). When the environmental impact is related to the food energy, the best option are first courses because they combine a low carbon footprint with a high energy content. The results of the work can be used both by the consumer, who can base the meal choice on environmental impact information, and by food services, who can adjust menus to achieve a more sustainable production

Mammography imaging studies using a laue crystal analyzer

Synchrotron based mammography imaging experiments have been performed with monochromatic x-rays in which a laue crystal placed after the object being imaged has been used to split the beam transmitted through the object. The X27C R&D beamline at the National Synchrotron Light Source was used with the white beam monochromatized by a double crystal Si(111) monochromator tuned to 18 keV. The imaging beam was a thin horizontal line approximately 0.5 mm high by 100 mm wide. Images were acquired in line scan mode with the phantom and detector both scanned together. The detector for these experiments was an image plate. A thin Si(l11) laue analyzer was used to diffract a portion of the beam transmitted through the phantom before the image plate detector. This ``scatter free`` diffracted beam was then recorded on the image plate during the phantom scan. Since the thin laue crystal also transmitted a fraction of the incident beam, this beam was also simultaneously recorded on the image plate. The imaging results are interpreted in terms of an x-ray schliere or refractive index inhomogeneities. The analyzer images taken at various points in the rocking curve will be presented

On the possibility to utilize a PCO Edge 4.2 bi scientific CMOS imager for extended ultra violet and soft X-ray photon detection

A state of the art commercial detector, a PCO Edge 4.2 bi based on a back illuminated sCMOS sensor developed for applications in the visible light/ultra violet regime has been adapted for ultra-high vacuum operations and has been characterized using soft X-ray in the energy range from 30 eV to 1000 eV. The imager features 2048 x 2048 pixel with a pixel size of 6.5 mu m x 6.5 mu m and allows full frame acquisitions at 48 Hz with a dynamic range of 88 dB at a noise level of 1.9 e(-). Spatial resolution and quantum efficiency have been elucidated in the aforementioned energy range at a soft X-ray beam line at Elettra Sincrotrone Trieste. The handiness of the camera as well as its Python library package allows easy and fast integration into the beam line environments of synchrotron sources and free electron lasers

Assessment of total annual effective doses to representative person, for authorised and accidental releases from the Nuclear Medicine Department at Cattinara Hospital (Trieste, Italy)

Purpose: Clinical procedures in a Nuclear Medicine Department produce radioactive liquid and solid waste. Regarding waste release into the environment from an authorised hospital, it is mandatory to verify the compliance with European Directive 2013/59/EURATOM, adopted by the Italian Government via the Legislative Decree 101/2020.Methods: Different activity release pathways into the environment from Trieste Nuclear Medicine Department have been analysed: liquid waste from patients' excreta discharged by sewage treatment system into the sea, and atmospheric releases following solid waste incineration. Reference models, provided by NCRP and IAEA guidelines, have been implemented to assess the impact of the discharged radioactivity for coastal waters and atmospheric transport conditions. Finally, an accidental fire event occurring in Radiopharmacy Laboratories has been simulated by HotSpot software.Results: Advanced screening models give an effective dose to population of 5.3 . 10-3 mu Sv/y and 1.4 . 10-4 mu Sv/y for introduction by sewage system into coastal waters and atmospheric releases by the incinerator, respectively. Workers involved in the maintenance of the sewage treatment plant receive a total annual effective dose of 3.8 mu Sv/y, while for incinerator staff the total annual exposure is 5.9 . 10-8 mu Sv/y. For the accidental fire event the maximum total effective dose to an individual results 3.8 . 10-8 Sv with mild wind, and 4.1 . 10-7 Sv with strong wind.Conclusions: The total annual effective doses estimated to representative person, due to both Nuclear Medicine authorised clinical practices and in case of an accidental fire event, are in compliance with regulatory stipula-tions provided by Directives

Multiscale X-ray phase-contrast tomography: From breast CT to micro-CT for virtual histology

Phase-contrast imaging techniques address the issue of poor soft-tissue contrast encountered in traditional X-ray imaging. This can be accomplished with the propagation-based phase-contrast technique by employing a coherent photon beam, which is available at synchrotron facilities, as well as long sample-to-detector distances. This study demonstrates the optimization of propagation-based phase-contrast computed tomography (CT) techniques for multiscale X-ray imaging of the breast at the Elettra synchrotron facility (Trieste, Italy). Two whole breast mastectomy samples were acquired with propagation-based breast-CT using a monochromatic synchrotron beam at a pixel size of 60 μm. Paraffin-embedded blocks sampled from the same tissues were scanned with propagation-based micro-CT imaging using a polychromatic synchrotron beam at a pixel size of 4 μm. Images of both methodologies and of the same sample were spatially registered. The resulting images showed the transition from whole breast imaging with propagation-based breast-CT methodology to virtual histology with propagation-based micro-CT imaging of the same sample. Additionally, conventional histological images were matched to virtual histology images. Phase-contrast images offer a high resolution with low noise, which allows for a highly precise match between virtual and conventional histology. Furthermore, those techniques allow a clear discernment of breast structures, lesions, and microcalcifications, being a promising clinically-compatible tool for breast imaging in a multiscale approach, to either assist in the detection of cancer in full volume breast samples or to complement structure identification in paraffin-embedded breast tissue samples

Spatio-temporal distribution and target species in a longline fishery off the southeastern coast of Brazil

No presente estudo, uma análise de agrupamento foi utilizada para classificar 6.486 lances feitos pela frota espinheleira sediada no Estado de São Paulo, Brasil, de 1998 até 2006, em relação à composição das espécies presentes nas capturas. Baseado nas proporções de doze espécies e três grupos de espécies, três agrupamentos foram identificados: C1: outros peixes; C2: tubarão-azul; C3: espadarte. Os resultados indicaram que ao longo do período estudado, a frota direcionou suas capturas principalmente para o tubarão-azul e para o espadarte, além de terem evidenciado que a importância do tubarão-azul nessa pescaria tem crescido progressivamente ao longo dos anos. Áreas mais afastadas da costa foram exploradas principalmente no primeiro e quarto trimestres (em especial a partir de 2001), enquanto que um esforço de pesca mais concentrado perto da quebra da plataforma continental foi observado durante o segundo e terceiro trimestres (para todo o período estudado). A frota espinheleira sediada em São Paulo mudou a estratégia de pesca para diferentes espécies-alvo, o que produziu importantes mudanças nas principais espécies capturadas por esforço de pesca (CPUE). A análise de agrupamento parece ter identificado apropriadamente essas alterações ao longo do tempo, em relação às quais não há, em geral, qualquer informação nos mapas de bordo.In the present study, a cluster analysis, in relation to the species composition of the catches, was used to classify 6,486 fishing sets by a longline fleet based in São Paulo State, Brazil, from 1998 to 2006. Based on the proportions of 12 species and three broader species groups, three clusters were identified: C1: other fishes; C2: blue shark; C3: swordfish. Results indicated that the fleet targeted mainly blue shark and swordfish and also showed that the blue shark importance in this fishery has been growing progressively trough the years. Offshore areas were exploited mainly in the first and fourth quarters (from 2001 mainly), while the fishing effort was more concentrated near the continental shelf break, during the second and third quarters (for the whole period). The longline fishery based in Sao Paulo State changed fishing strategy to target different species which produced important changes in catch-per-unit-effort (CPUE) of the main species caught. Cluster analysis seems to have appropriately identified these changes over time, which is an important information, often missing in logbooks

A New Expression for the Gain-Noise Relation of Single-Carrier Avalanche Photodiodes With Arbitrary Staircase Multiplication Regions

We propose a simple expression to relate the total excess noise factor of a single-carrier multiplication staircase avalanche photodiode (APD) to the excess noise factor and gain given by the individual conduction band discontinuities. The formula is valid when electron impact ionization dominates hole impact ionization; hence, it is especially suited for staircase APDs with In-rich multiplication regions, as opposed, for example, to GaAs/AlGaAs systems where hole ionization plays an important role. The formula has been verified by accurate means of numerical simulations based on a newly developed nonlocal history dependent impact ionization model