10 research outputs found
Optimization of GaInNAs quantum-well vertical-cavity surface-emitting laser emitting at 2.33 ÎŒm
Produção de forragem e carga animal em pastagens de capim-elefante consorciadas com azevém, espécies de crescimento espontùneo e trevo-branco ou amendoim forrageiro
Anålise da relação entre dois métodos indicadores de estado nutricional em escolares
Objetivo: Verificar a concordĂąncia de diagnĂłsticos a partir do uso de dois mĂ©todos indicadores de estado nutricional âĂndice de massa corporal (IMC) e percentual de gordura corporal (% GC)â em escolares de 6 a 12 anos de idade de trĂȘs municĂpios do estado do Rio Grande do Sul, Brasil.
MĂ©todo: O grupo de estudo foi composto por 507 escolares, sendo 261 meninos e 246 meninas. Foram coletadas variĂĄveis antropomĂ©tricas, para o cĂĄlculo do IMC e do % GC, utilizando-se para a classificação os critĂ©rios de referĂȘncia de Conde e Monteiro (2006) e de Lohman (1987), respectivamente.
Resultados: Os resultados foram analisados pela correlação de Pearson e pelo Ăndice kappa. Os dados indicaram correlação positiva de 0,89 para meninos e 0,78 para meninas entre as variĂĄveis. A concordĂąncia entre os mĂ©todos analisados atravĂ©s do Ăndice kappa, demonstrou que 54,9% das meninas e 56,7% dos meninos foram classificados na mesma categoria pelos dois procedimentos.
ConclusĂŁo: Pode-se concluir que apesar de se evidenciar elevada correlação entre os mĂ©todos IMC e % GC, estes apresentam discrepĂąncias ao classificar indivĂduos na faixa etĂĄria de 6 - 12 anos, sendo esta ainda mais acentuada em relação Ă categoria baixo peso. Desse modo, Ă© necessĂĄrio cautela ao utilizar o IMC como parĂąmetro para o diagnĂłstico do estado nutricional de crianças
PTV-based VMAT vs. robust IMPT for head-and-neck cancer: A probabilistic uncertainty analysis of clinical plan evaluation with the Dutch model-based selection
Background and purpose: In the Netherlands, head-and-neck cancer (HNC) patients are referred for proton therapy (PT) through model-based selection (MBS). However, treatment errors may compromise adequate CTV dose. Our aims are: (i) to derive probabilistic plan evaluation metrics on the CTV consistent with clinical metrics; (ii) to evaluate plan consistency between photon (VMAT) and proton (IMPT) planning in terms of CTV dose iso-effectiveness and (iii) to assess the robustness of the OAR doses and of the risk toxicities involved in the MBS. Materials and methods: Sixty HNC plans (30 IMPT/30 VMAT) were included. A robustness evaluation with 100,000 treatment scenarios per plan was performed using Polynomial Chaos Expansion (PCE). PCE was applied to determine scenario distributions of clinically relevant dosimetric parameters, which were compared between the 2 modalities. Finally, PCE-based probabilistic dose parameters were derived and compared to clinical PTV-based photon and voxel-wise proton evaluation metrics. Results: Probabilistic dose to near-minimum volume v = 99.8% for the CTV correlated best with clinical PTV-D98% and VWmin-D98%,CTV doses for VMAT and IMPT respectively. IMPT showed slightly higher nominal CTV doses, with an average increase of 0.8 GyRBE in the median of the D99.8%,CTV distribution. Most patients qualified for IMPT through the dysphagia grade II model, for which an average NTCP gain of 10.5 percentages points (%-point) was found. For all complications, uncertainties resulted in moderate NTCP spreads lower than 3 p.p. on average for both modalities. Conclusion: Despite the differences between photon and proton planning, the comparison between PTV-based VMAT and robust IMPT is consistent. Treatment errors had a moderate impact on NTCPs, showing that the nominal plans are a good estimator to qualify patients for PT.RST/Reactor Physics and Nuclear Material