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Importance of the elemental composition in brachytherapy with neutrons ; Importancia de la composicion elemental en braquiterapia con neutrones. Paredes G, L. Mexico ; Azorin N, J. Mexico ; Francois L, J. An analysis is presented of as the small differences that exist in the elementary composition of the wicked tumors, healthy fabrics and some material substitutes of fabric employees in dosimetry, they generate variations in the value of the kerma coefficient and consequently in the absorbed dose of neutrons in the interval 11 eV to 29 MeV.

Adicionalmente, se establece un mecanismo Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf sources; Importancia del coeficiente de kerma de neutrones en la planeacion de tratamientos de Braquiterapia con fuentes de Cf Mexico ]. The Cf is a fast neutrons emitting radioisotope by spontaneous fission that can be used as sealed source in medicine applications, industry and research.

In medicine new applications are being developed for the treatment of patient with hypoxic and voluminous tumors, where the therapy with photons has not given positive results, as well as for the protocols of therapy treatment by boron neutron capture, where very small sources of Cf will be used with the interstitial brachytherapy technique of high and low dose rate.

In this work an analysis of how the small differences that exist in the elementary composition of 4 wicked tumors, 4 ICRU healthy tissues and 3 substitute materials of ICRU tissue used in dosimetry are presented, its generate changes in the neutrons kerma coefficient in function of the energy and consequently in the absorbed dose in the interval of 11 eV to 29 MeV.

Directory of Open Access Journals Sweden. Entre y se trataron cerca de 50 enfermos con tumores cerebrales malignos. Neutron Assay System for Con? Frame, Katherine C. Waste will be removed from confinement vessels remaining from s-era experiments. In order to dispose of the vessels, debris and contamination must be removed.

Neutron assay system was designed to assay vessels before and after cleanout. Initial design parameters arethe use of 4-atm 3 He tubes with length of 6 feet, and 3 He tubes embedded in polyethelene for moderation. Assay uncertainty depends on five factors: 1 Statistical uncertainty in the assay measurement; 2 Statistical uncertainty in the background measurement; 3 Statistical uncertainty in the isotopics determination - This should be much smaller than the other uncertainties; 4 Systematic uncertainty due to position bias; and 5 Systematic uncertainty due to fluctuations in cosmic ray spallation.

This one can be virtually eliminated by performing the background measurement with an empty vessel - but that may not be possible. We used modeling and experiments to quantify the systematic uncertainties. The calibration assumes a uniform distribution of material, but reality will be different. MCNPX modeling was used to quantify the positional bias. The model was benchmarked to build confidence in its results. Cosmic ray spallation contributes significantly to the background.

Comparing rates. The epithermal critical experiments; Experiences critiques avec des neutrons epitliermiques; Nadteplovye kriticheskie ehksperimenty; Experimentos criticos con neutrones epitermicos. De plus, on fait osciller des sources artificielles de neutrons , etalonnees entre elles, pour determiner les differentes fonctions neutroniques importantes au centre du montage. Une methode de traitement numerique permettra de grouper toutes les mesures en un fichier autonome de sections efficaces moyennes par spectre.

Se esta estudiando una serie de nueve conjuntos criticos de varias regiones, con acoplamiento termico-rapido, de forma pseudoesferica, del tipo alveolar de cuerpo dividido. Hasta ahora se han puesto en servicio tres conjuntos de esa indole. Ademas, se hacen oscilar fuentes artificiales de neutrones intercalibradas para determinar las diferentes funciones neutronicas que revisten importancia en el centro del conjunto.

Los espectros se obtienen procediendo a mediciones con contadores de fision. Braquiterapia de alta taxa de dose no Brasil High-dose rate brachytherapy in Brazil. Full Text Available A braquiterapia de alta taxa de dose foi introduzida em nosso meio em janeiro de High-dose rate brachytherapy was first introduced in Brazil in January Significant changes in the management of malignant neoplasms were observed since utilization of high-dose rate brachytherapy.

The high number of gynecological patients awaiting for brachytherapy also decreased during this period. In the first ten years 26, patients were treated with high-dose rate brachytherapy. In this study we present the number and profile of the patients treated with high-dose rate brachytherapy as well as the distribution of these patients in the Brazilian territory, proving the benefit of the use of high-dose rate brachytherapy in Brazil.

For both reactions, leaching and transformation, the reagents concentration, agitation speed and temperature influences were studied and the activation energies were found. Author 18 refs. Phase transformations in lithium aluminates irradiated with neutrons ; Transformaciones de fase en aluminatos de litio irradiados con neutrones. Carrera, L. The lithium aluminate like candidate to be used in the coverings producers of tritium in the fusion nuclear reactors, presents high resistance to the corrosion to the one to be stuck to structural materials as special steels.

However, the crystallographic changes that take place in the cover that is continually subjected to irradiation with neutrons , can alter its resistance to the corrosion. In this work the changes of crystalline structure are shown that they present two types of nano structures of lithium aluminates, subjected to an average total dose 7.

The studied nano structures presented only phase transformations without formation of amorphous material. Neutron spectrometry with organic scintillation detector; Espectrometria de nuetrones con cristales de centelleo organicos. This work describes a fast neutron spectrometer using a stilbene crystal as head detector with pulse shape discrimination P. Tre experimental procedure involves the P. It is also presented the measurement of the spectrum of the fast reactor CCRAl Author 17 refs.

Full Text Available Due to their adequate time-resolution, high temperature Powder Neutron Diffraction applied to reaction-sintering process allows in situ reaction analyses and transient phase identifications, which otherwise cannot be detected by quenching and conventional diffraction methods.

The activation energy for dolomite and calcite breakup was calculated from fitting to a contracting sphere model. Adicionalmente, mediante. Neutrons production during the interaction of monoenergetic electrons with a thin tungsten target; Produccion de neutrones durante la interaccion de electrones monoenergeticos con un blanco delgado de tungsteno.

Soto B, T. Mexico ; Baltazar R, A. Mexico ; Vega C, H. La Penuela, Zacatecas, Zac. When a linear accelerator for radiotherapy operates with acceleration voltages higher than 8 MV, neutrons are produced, as secondary radiation which deposits an undesirable and undesirable dose in the patient. The spectra of photons and neutrons were estimated in 4 point detectors placed at different equidistant points from the center of the lamella.

Neutron production in the interaction of electrons with a dispersing lamella; Produccion de neutrones en la interaccion de electrones con una laminilla dispersora. When a Linac for radiotherapy operates with acceleration voltages greater than 8 MV, neutrons are produced as secondary radiation. They deposit an undesirable and not negligible dose in the patient. When a Linac operates with electron beams, the beam that leaves the magnetic baffle is incised in the dispersion foil in order to cause quasi-elastic interactions and expand the spatial distribution of the electrons; in their interaction with the lamella the electrons produce photons and these in turn produce neutrons.

Due to the radiobiological efficiency of neutrons and the ways in which they interact with matter, is important to determine the neutrons production in Linacs operating in electron mode.

The objective of this work is to determine the characteristics of photons and neutrons that occur when a beam of mono-energetic electrons of 2 mm in diameter pencil beam is made to impinge on a tungsten lamella of 1 cm in diameter and 0.

The spectra of photons and neutrons were estimated in 6 point detectors, four were placed in different points equidistant from the center of the lamella and the other two were located at 50 cm and 1 m from the electron beam, simulating the totally closed head.

In this work it was found that when a Linac operates with an electron beam of 12 or 18 MeV there is neutron production mainly in the head and in the direction of the beam. Design of a versatile detector for the detection of charged particles, neutrons and gamma rays. Neutron interaction with the matter; Diseno de un detector versatil para la deteccion de particulas cargadas, neutrones y rayos gamma.

Interaccion neutronica con la materia. The Fostron detector detects charged particles, neutrons and gamma rays with a reasonable discrimination power. Because the typical detectors for neutrons present a great uncertainty in the detection, this work was focused mainly to the neutron detection in presence of gamma radiation. Also there are mentioned the advantages and disadvantages of the Fostron detector. Somatic mutation and recombination induced with reactor thermal neutrons in Drosophila melanogaster; Mutacion y recombinacion somaticas inducidas con neutrones termicos de reactor en Drosophila melanogaster.

Zambrano A, F. A linear relation between the radiation equivalent dose and the frequency of the genetic effects such as mutation and recombination was observed. The obtained results allow to conclude that SMART is a sensitive system to the induced damage by neutrons , so this can be used for studying its biological effects.

Non-invasive neutron diffraction analysis of marbles from the 'Edificio con Tre Esedre' in Villa Adriana. Filabozzi, A. Roman marble fragments from the Villa Adriana at Tivoli Rome have been characterised by neutron diffraction. This study aimed at distinguishing between different marble types on the basis of the mineral phase compositions and the crystallographic textures. It is demonstrated that on a multi-detector time-offlight neutron diffractometer a quantitative bulk texture analysis can be performed on a stationary marble sample in a matter of minutes.

This potentially allows investigating large sample series or bulky, intact marble objects in a completely nondestructive manner. The texture information, along with other structure details, can be used as characterising feature to address questions of attribution and restoration of archaeological marble objects. Tratamiento conservador en pacientes con retinoblastoma bilateral. El rango de edad fue de meses en el grupo 1 y de meses en el grupo 2.

El tiempo de seguimiento fue de meses para el grupo 1 y de meses para el grupo 2. Optimization in brachytherapy with the implementation of Radiobiology; Optimizacion en Braquiterapia con la implementacion de la Radiobiologia. Duran, M. Viamonte , Buenos Aires Argentina. In this work we wish to show the implementation of radiobiological concepts in the optimization.

Assuming that the subtiles differences that result in the dose distribution among the different optimization models which are not visible in an isodose plane, it is studied how is classically make it , the quality implant through natural histograms about dose volumes and the resulting parameters.

Also is studied the necrosis probability which may be caused by the choice of some optimization model, allowing with this the choice of the best implant. Corno, S.


Tratamiento del Carcinoma de PrĂ³stata con Braquiterapia de Baja Tasa

Pasteau O, and Degrais P The radium treatment of cancer of the prostate. J D'Urol ; Retropubic implantation of Iodine I the treatment of prostate cancer. J Urol ; Anderson L L. Spacing nomographs for interstitial implants of seeds.


Braquiterapia de Baja Tasa Con Yodo 125, Para Tumores Cerebrales

Importance of the elemental composition in brachytherapy with neutrons ; Importancia de la composicion elemental en braquiterapia con neutrones. Paredes G, L. Mexico ; Azorin N, J. Mexico ; Francois L, J. An analysis is presented of as the small differences that exist in the elementary composition of the wicked tumors, healthy fabrics and some material substitutes of fabric employees in dosimetry, they generate variations in the value of the kerma coefficient and consequently in the absorbed dose of neutrons in the interval 11 eV to 29 MeV.


Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Prada and Miguel A. Prada , Miguel A.

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