Quality Control of Ionizing Radiation in Radiotherapy

This work includes the results of our research on the measurement of the dose delivered by an external beam in radiotherapy. The use of scintillating fibers in high-energy experiments produced rapid and reliable results and allows new dosimeters to be built and extends their use to measure the dose of an external beam of electrons, photons, and hadrons in radiotherapy.The chapter starts from the description of the radiation used in radiotherapy, presents the new approaches and then the tools used to perform the quality control of therapeutic beams, and finally shows the characteristics and differences compared to the traditional quality controls by using our results on the scintillating fibers used as a dosimeter. Some care should be taken into account during the collection and processing of data, for the treatment of some systematic errors in the method. In this chapter, we describe the procedure to be followed

Search for heavy neutral lepton production in K+ decays

A search for heavy neutral lepton production in K + decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the 10−7 to 10−6 level are established on the elements of the extended neutrino mixing matrix |Ue4| 2 and |Uμ4| 2 for heavy neutral lepton mass in the ranges 170–448 MeV/c2 and 250–373 MeV/c2, respectively. This improves on the previous limits from HNL production searches over the whole mass range considered for |Ue4|2 and above 300 MeV/c2 for |Uμ4|2

Measurement of the very rare K+→π+ννˉK^+ \to \pi^+ \nu \bar\nu decay

The decay K+→π+νν¯ , with a very precisely predicted branching ratio of less than 10−10 , is among the best processes to reveal indirect effects of new physics. The NA62 experiment at CERN SPS is designed to study the K+→π+νν¯ decay and to measure its branching ratio using a decay-in-flight technique. NA62 took data in 2016, 2017 and 2018, reaching the sensitivity of the Standard Model for the K+→π+νν¯ decay by the analysis of the 2016 and 2017 data, and providing the most precise measurement of the branching ratio to date by the analysis of the 2018 data. This measurement is also used to set limits on BR(K+→π+X ), where X is a scalar or pseudo-scalar particle. The final result of the BR(K+→π+νν¯ ) measurement and its interpretation in terms of the K+→π+X decay from the analysis of the full 2016-2018 data set is presented, and future plans and prospects are reviewed

Huella de carbono parcial de la lecheria uruguaya

Este artículo presenta la metodología y los resultados de la huella de carbono parcial de la lechería uruguaya, estimada a partir de datos de la Encuesta Lechera del ejercicio 2019. Para los tambos remitentes del país, la huella promedio es de 0,986 kg CO2eq/kg de leche, con un rango que abarca desde 0,883 a 1,387 kg CO2eq./kg de leche. Este resultado coloca a la lechería uruguaya en una posición favorable en una perspectiva internacional

Huella de carbono parcial de la lecheria uruguaya

Este artículo presenta la metodología y los resultados de la huella de carbono parcial de la lechería uruguaya, estimada a partir de datos de la Encuesta Lechera del ejercicio 2019. Para los tambos remitentes del país, la huella promedio es de 0,986 kg CO2eq/kg de leche, con un rango que abarca desde 0,883 a 1,387 kg CO2eq./kg de leche. Este resultado coloca a la lechería uruguaya en una posición favorable en una perspectiva internacional

Polyurethane-silica hybrid foam by sol-gel approach: chemical and functional properties

Hybrid foams based on polyurethane and polysiloxane-domains were designed in terms of chemical structure and hierarchical morphology to improve the thermal insulation capability of conventional polyurethane foams. Polysiloxane-domains by solegel approach reacted with polyols to produce a polysiloxane-reactive-adduct, which completed its formation into polysiloxane aerogel-like structure during the polyurethane foaming process. Hybrids with 5wt% of the polysiloxane-domains exhibited a 22% reduction in thermal conductivity in comparison with pristine PUR. The chemical structure and the hierarchical morphology were studied by means of SAXS/WAXS and 29Si and 13C NMR. In particular the hybrid structure consisted of coarse polysiloxane-fractal-aggregates composed of silica nanoparticles embedded in the polyurethane matrix. Morphological analysis revealed a decrease of the cell size with the increase of the siloxane content ascribed to the nucleation effect of polysiloxane-domains during the foaming. The cell size reduction and the formation of hybrid-aerogel-like structures within the cell-walls are considered the key factors to reduce the thermal conductivity of hybrid foams

CT imaging of the internal human ear: Test of a high resolution scanner

During the course of 2009, in the framework of a project supported by the National Institute of Nuclear Physics, a number of tests were carried out at the Department of Physics of the University of Bologna in order to achieve a good quality CT scan of the internal human ear. The work was carried out in collaboration with the local “S. Orsola” Hospital in Bologna and a company (CEFLA) already involved in the production and commercialization of a CT scanner dedicated to dentistry. A laboratory scanner with a simple concept detector (CCD camera-lens-mirror-scintillator) was used to see to what extent it was possible to enhance the quality of a conventional CT scanner when examining the internal human ear. To test the system, some conventional measurements were made, such as the spatial resolution calculation with the MTF and dynamic range evaluation. Different scintillators were compared to select the most suitable for the purpose. With 0.5 mm thick structured cesium iodide and a field of view of 120×120 mm2, a spatial resolution of 6.5l p/mm at 5% MTF was obtained. The CT of a pair of human head phantoms was performed at an energy of 120 kVp. The first phantom was a rough representation of the human head shape, with soft tissue made of coarse slabs of Lucite. Some inserts, like small aluminum cylinders and cubes, with 1 mm diameter drilled holes, were used to simulate the channels that one finds inside the human inner ear. The second phantom is a plastic PVC fused head with a real human cranium inside. The bones in the cranium are well conserved and the inner ear features, such as the cochlea and semicircular channels, are clearly detectable. After a number of CT tests we obtained good results as far as structural representation and channel detection are concerned. Some images of the 3D rendering of the CT volume are shown below. The doctors of the local hospital who followed our experimentation expressed their satisfaction. The CT was compared to a virtual endoscopy and judged particularly useful for clinical pre-surgery diagnostics. The experimentation proceeds with a faster scanner now under development in our laboratories. We believe this work could be of a certain interest for the medical imaging world