GEANT4 application for the simulation of the head of a siemens primus linac

The Monte Carlo simulation of the head of a Siemens Primus Linac used at Virgen Macarena Hospital (Sevilla, Spain) has been performed using the code GEANT4 [1-2], version 9.2. In this work, the main features of the application built by our group are presented. They are mainly focused in the optimization of the performance of the simulation. The geometry, including the water phantom, has been entirely wrapped by a shielding volume which discards all the particles escaping far away through its walls. With this, a factor of four in the time spent by the simulation can be saved. An interface to read and write phase-space files in IAEA format has been also developed to save CPU time in our simulations [3-4]. Finally, some calculations of the dose absorption in the water phantom have been done and compared with the results given by EGSnrc [5] and with experimental data obtained for the calibration of the machine

Prácticas pedagógicas mediadas por TIC en la enseñanza de la comprensión lectora y de los sistemas geométricos de tres docentes de una institución educativa pública de la ciudad de Pereira

El siguiente proyecto contiene los resultados de una investigación cualitativa realizada con tres docentes de una Institución Educativa Pública de la ciudad de Pereira, con el propósito de comprender los usos que hacen de las Tecnologías de la Información y la Comunicación (TIC) para la enseñanza de la comprensión lectora y los sistemas geométricos en los grados primero, segundo y tercero, apoyándose en la red social educativa Edmodo y dos secuencias didácticas mediadas por TIC. Metodológicamente se llevó a cabo una etnografía como diseño de investigación que permite recoger, comprender e interpretar información de tres docentes en las aulas de clase. Se diseñaron y aplicaron instrumentos como diarios de campo, rejillas, y videos, que posteriormente permitieron explicar y comprender las prácticas de las docentes al usar las TIC para la enseñanza del lenguaje y las matemáticas, a través de dos secuencias didácticas mediadas por TIC y la red social educativa Edmodo, además de tecnologías complementarias, dentro de las cuales se pueden hallar herramientas de video, sonido, así como programas disponibles en los recursos tecnológicos

Purification of free arginine from chickpea (Cicer arietinum) seeds

© 2015 Elsevier Ltd. All rights reserved. Chickpea is a grain legume widely consumed in the Mediterranean region and other parts of the world. Chickpea seeds are rich in proteins but they also contain a substantial amount of free amino acids, especially arginine. Hence chickpea may represent a useful source of free amino acids for nutritional or pharmaceutical purposes. Arginine is receiving great attention in recent years because it is the substrate for the synthesis of nitric oxide, an important signaling molecule involved in numerous physiological and pathological processes in mammals. In this work we describe a simple procedure for the purification of arginine from chickpea seeds, using nanofiltration technology and an ion-exchange resin, Amberlite IR-120. Arginine was finally purified by precipitation or crystallization, yielding preparations with purities of 91% and 100%, respectively. Chickpea may represent an affordable green source of arginine, and a useful alternative to production by fermentation or protein hydrolysis.This work was carried out with the financial support of Junta de Andalucía (Spain) to the Laboratory of Bioactive and Functional Components of Plant Products (Instituto de la Grasa, C.S.I.C.). Cristina Megias is recipient of a JAE-Doc (C.S.I.C.) contract from the “Junta para la Ampliación de Estudios” program (cofinanced by the European Social Fund). Isabel Cortés-Giraldo is recipient of a JAE-Pre (C.S.I.C) fellowship from the “Junta para la Ampliación de Estudios” program (cofinanced by the European Social Fund). Thanks are due to María Dolores García-Contreras for technical assistance and to Jose Julian Rios for HPLC-MS analyses of purified arginine.Peer Reviewe

LabVIEW-based control and acquisition system for the dosimetric characterization of a silicon strip detector

Theaimofthisworkistopresentanewdataacquisition,control,andanalysissoftwaresystemwrittenin LabVIEW.Thissystemhasbeendesignedtoobtainthedosimetryofasiliconstripdetectorinpolyethylene. It allows the full automation of the experiments and data analysis required for the dosimetric characterization of silicon detectors. It becomes a useful tool that can be applied in the daily routine check of a beam accelerator.MINECO ICTI2013-2016/FPA2013-47327-C2-1-RMINECO ICTI2013-2016/FPA2014-53290-C2-2- PJunta de Andalucía P12-FQM-160

Feasibility Study of a Proton Irradiation Facility for Radiobiological Measurements at an 18 MeV Cyclotron

A feasibility study of an experimental setup for the irradiation of biological samples at the cyclotron facility installed at the National Centre of Accelerators (Seville, Spain) is presented. This cyclotron, which counts on an external beam line for interdisciplinary research purposes, produces an 18 MeV proton beam, which is suitable for the irradiation of mono-layer cultures for the measurement of proton cell damages and Relative Biological Effectiveness (RBE) at energies below the beam nominal value. Measurements of this kind are of interest for proton therapy, since the variation of proton RBE at the distal edge of the Bragg curve may have implications in clinical proton therapy treatments. In the following, the characteristics of the beam line and the solutions implemented for the irradiation of biological samples are described. When dealing with the irradiation of cell cultures, low beam intensities and broad homogeneous irradiation fields are required, in order to assure that all the cells receive the same dose with a suitable dose rate. At the cyclotron, these constraints have been achieved by completely defocusing the beam, intercepting the beam path with tungsten scattering foils and varying the exit-window-to-sample distance. The properties of the proton beam thus obtained have been analysed and compared with Monte Carlo simulations. The results of this comparison, as well as the experimental measurement of the lateral dose profiles expected at the position of samples are presented. Meaningful dose rates of about 2–3 Gy/min have been obtained. Homogeneous lateral dose profiles, with maximum deviations of 5%, have been measured at a distance of approximately 50 cm in air from the exit window, placing a tungsten scattering foil of 200 μm in the beam path

Determination of -Cyano-L-alanine, -Glutamyl--cyano-L-alanine, and Common Free Amino Acids in Vicia sativa (Fabaceae) Seeds by Reversed-Phase High-Performance Liquid Chromatography

A method for determination of -cyano-L-alanine, -glutamyl--cyano-L-alanine and other free amino acids in Vicia sativa is presented. Seed extracts were derivatized by reaction with diethyl ethoxymethylenemalonate and analyzed by reverse-phase highperformance liquid chromatography. Calibration curves showed very good linearity of the response. The limit of detection and quantification was 0.15 and 0.50 M, respectively. The method has high intra-(RSD = 0.28-0.31%) and interrepeatability (RSD = 2.76-3.08%) and remarkable accuracy with a 99% recovery in spiked samples. The method is very easy to carry out and allows for ready analysis of large number of samples using very basic HPLC equipment because the derivatized samples are very stable and have very good chromatographic properties. The method has been applied to the determination of -glutamyl--cyano-L-alanine, -cyano-L-alanine, and common free amino acids in eight wild populations of V. sativa from southwestern Spain

Performance of the reconstruction algorithms of the FIRST experiment pixel sensors vertex detector

Hadrontherapy treatments use charged particles (e.g. protons and carbon ions) to treat tumors. During a therapeutic treatment with carbon ions, the beam undergoes nuclear fragmentation processes giving rise to significant yields of secondary charged particles. An accurate prediction of these production rates is necessary to estimate precisely the dose deposited into the tumours and the surrounding healthy tissues. Nowadays, a limited set of double differential carbon fragmentation cross-section is available. Experimental data are necessary to benchmark Monte Carlo simulations for their use in hadrontherapy. The purpose of the FIRST experiment is to study nuclear fragmentation processes of ions with kinetic energy in the range from 100 to 1000 MeV/u. Tracks are reconstructed using information from a pixel silicon detector based on the CMOS technology. The performances achieved using this device for hadrontherapy purpose are discussed. For each reconstruction step (clustering, tracking and vertexing), different methods are implemented. The algorithm performances and the accuracy on reconstructed observables are evaluated on the basis of simulated and experimental data

Novel dual single sided silicon strip detector chip for radiotherapy verification

A novel dual single sided silicon strip detector (SSSSD) chip was designed to meet clinical requirements in radiotherapy verification. An available design from Micron Semiconductor Ltd. (BB7, 500 µ m thick) was the base of a two-dimensional detector adapted into a special configuration with the aim of uniforming and minimizing foreing materials around the active area (64 × 64 mm2). With this purpose, two independent BB7 SSSSDs were mounted in a perpendicular configuration, separated by a 500 µ m kapton dielectric film with the same dimensions as the silicon wafers, thus minimizing air gaps in between. This new configuration, called the dual SSSSD chip design, was mounted on kapton printed circuit board (PCB). Both silicon wafers were divided into 32 strips, 2 mm width each. The aim of developing this detector was to allow 2D dose measurements, improve spatial resolution and perform radiotherapy treatment verification faster than with a previous prototype. Characteristics and performance of the novel detector are presented

Performance of upstream interaction region detectors for the FIRST experiment at GSI

The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI has been designed to study carbon fragmentation, measuring 12C double differential cross sections (∂2σ/ ∂θ∂E) for different beam energies between 100 and 1000 MeV/u. The experimental setup integrates newly designed detectors in the, so called, Interaction Region around the graphite target. The Interaction Region upstream detectors are a 250 μm thick scintillator and a drift chamber optimized for a precise measurement of the ions interaction time and position on the target. In this article we review the design of the upstream detectors along with the preliminary results of the data taking performed on August 2011 with 400 MeV/u fully stripped carbon ion beam at GSI. Detectors performances will be reviewed and compared to those obtained during preliminary tests, performed with 500 MeV electrons (at the BTF facility in the INFN Frascati Laboratories) and 80 MeV/u protons and carbon ions (at the INFN LNS Laboratories in Catania)