Photon Beams
Mostrando 1-12 de 14 artigos, teses e dissertações.
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1. Determinação do espectro de energia de campos de radiação utilizados em radioterapia a partir de medidas de atenuação e simulação Monte Carlo / Determination of the spectra of radiation beams used in radiotherapy from attenuation measurements and Monte Carlo simulation
As propriedades dosimétricas de um feixe de radiação utilizado em Radioterapia estão diretamente ligadas ao espectro de energia produzido pela unidade de tratamento. Dessa forma, o desenvolvimento de metodologias que permitam avaliar de forma simples e acurada os espectros de feixes clínicos pode auxiliar no estabelecimento da qualidade dos tratamentos
Publicado em: 2010
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2. Assessment of radiotherapic treatments with thermoluminescent dosimetry / Verificação de tratamentos radioterápicos diversos com dosimetria termoluminescente
The last decades noticed a massive improvement in radiotherapy techniques and the use of segmented beams produced by multileaf collimators. However, the dose radiation therapy planning systems (TPS) in use are characterized by the restriction of access to the calculation algorithms. The aim of this work was to compare dose values measured in an anthropomorph
Publicado em: 2007
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3. Acoplamento de dois feixes com lasers de femtossegundos em vapor de Rb
Femtosecond lasers operating in the mode-locked regime have a repetition rate determined by the round trip time of the pulse inside the laser cavity (TR = 2L/c). For Ti:sapphire lasers the repetition rate is typically of the order of 100 MHz, with TR 10 ns. Under this condition TR may be smaller then the population relaxation time (T1) and the coher
Publicado em: 2007
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4. Métodos para implementação da dosimetria in vivo (dose de entrada) com dosímetros termoluminescentes na radioterapia externa com feixe de fóton / Methods for implementation of in vivo dosimetry (entrance dose) using thermoluminescent dosimeters during radiotherapy treatment with photon beam
Neste trabalho, estão descritos os métodos de seleção, calibração e de determinação dos fatores de correção, as características físicas dos dosímetros termoluminescentes, o procedimento de cálculo para converter a leitura do dosímetro em dose absorvida e a metodologia para se determinar a dose de entrada. Foram investigadas a praticidade e a u
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 23/11/2006
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5. Implantação de um programa de controle de qualidade para sistemas de planejamento de tratamento computadorizados de acordo com o TRS 430 / Implementation of a quality assurance program for computerized treatment planning systems according to TRS 430
This work presents the guidelines and necessary tests tom implement a quality assurance program for Eclipse 7.3.10 from Varian at Hospital das Clinicas, Sao Paulo University School of Medicine - Brazil, in accordance with the new IAEA publication TRS 430. The recommended tests for the TRS 430 air mainly classified into acceptance tests, commissioning (dosime
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 27/04/2006
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6. DependÃncia angular de uma ressonÃncia de transparÃncia induzida eletromagneticamente: aplicaÃÃo à velocimetria de Ãtomos frios
In this work, we have demonstrated how the effect of electromagnetically induced transparency can be applied for temperature measurements of cold atoms. The principle of the technique is based on the high sensibility of this ressonance to the angle between the incident light beams, in the low intensities limit. This effect results from the residual Doppler b
Publicado em: 2005
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7. Individual monitoring for external exposures: experimentation and simulation with Monte Carlo Method / Monitoração individual externa: experimentos e simulações com o método de Monte Carlo
In this work, we have evaluated the possibility of applying the Monte Carlo simulation technique in photon dosimetry of external individual monitoring. The GEANT4 toolkit was employed to simulate experiments with radiation monitors containing TLD-100 and CaF2:NaCl thermoluminescent detectors. As a first step, X ray spectra were generated impinging electrons
Publicado em: 2005
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8. Espectroscopia Ãptica nÃo linear em sistemas atÃmicos envolvendo nÃveis de Rydberg
In this thesis we study nonlinear optical effects in alkali vapors, in which Rydberg levels play the role of near resonant intermediate levels, focusing our attention in processes such as: four wave mixing (FWM), two photon absorption, sum frequency generation (SF) and difference frequency generation (DF). We analyze a FWM process with two-photon transitions
Publicado em: 2002
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9. Geração de fotons muito duro por espalhamento Compton inverso da radiação sincrotron
The most efficient mechanism to generate photons in the 100 MeV energy range is by Inverse Compton scattering (ICS) of laser from relativistic electron. The energy of the emitted photons can be increased by raising either the energy of the electron, which is very expensive, or that of the photon. with the suggestion (S. Caticha-Ellis, 1983) that intense X-ra
Publicado em: 1993
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10. Experimental determination of radiation dose distribution in an heterogeneous medium, irradiated with clinical beams of x and gamma rays / Determinação experimental da distribuição de dose de radiação em meio heterôgenio, irradiado por raios-x e gama radioterápicos
An experimental study of the perturbation caused by a cylindrical inhomogeneity of aluminium on dose distribution in a water phantom, irradiated by high energy photons used in radiation therapy, was performed, employing radiographic film as dosimeter. With these materials we intended to simulate the interface between bone and muscular tissue. The film was pl
Publicado em: 1989
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11. Espectroscopia optica sub-doppler diferencial de misturas gasosas interagentes entre si, com lasers : espectros de absorção e dispersão em regime estacionario
We consider in this work the absorption and dispersion differential optical sub-Doppler spectra of a binary mixture of two mutually interacting gases with lasers, in order to obtain directly in the optical spectra the effects of such na interaction. The interactions are restricted to binary collisions and are treated in the so called binary approximation. In
Publicado em: 1987
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12. Liquid scintillator for 2D dosimetry for high-energy photon beams
Complex radiation therapy techniques require dosimetric verification of treatment planning and delivery. The authors investigated a liquid scintillator (LS) system for application for real-time high-energy photon beam dosimetry. The system was comprised of a transparent acrylic tank filled with liquid scintillating material, an opaque outer tank, and a CCD c
American Association of Physicists in Medicine.