Inter- and intrafractional 4D dose accumulation for evaluating ΔNTCP robustness in lung cancer.

BACKGROUND AND PURPOSE Model-based selection of proton therapy patients relies on a predefined reduction in normal tissue complication probability (NTCP) with respect to photon therapy. The decision is necessarily made based on the treatment plan, but NTCP can be affected when the delivered treatment deviates from the plan due to delivery inaccuracies. Especially for proton therapy of lung cancer, this can be important because of tissue density changes and, with pencil beam scanning, the interplay effect between the proton beam and breathing motion. MATERIALS AND METHODS In this work, we verified whether the expected benefit of proton therapy is retained despite delivery inaccuracies by reconstructing the delivered treatment using log-file based dose reconstruction and inter- and intrafractional accumulation. Additionally, the importance of two uncertain parameters for treatment reconstruction, namely deformable image registration (DIR) algorithm and α/β ratio, was assessed. RESULTS The expected benefit or proton therapy was confirmed in 97% of all studied cases, despite regular differences up to 2 percent point (p.p.) NTCP between the delivered and planned treatments. The choice of DIR algorithm affected NTCP up to 1.6 p.p., an order of magnitude higher than the effect of α/β ratio. CONCLUSION For the patient population and treatment technique employed, the predicted clinical benefit for patients selected for proton therapy was confirmed for 97.0 % percent of all cases, although the NTCP based proton selection was subject to 2 p.p. variations due to delivery inaccuracies

Platform for automatic patient quality assurance via Monte Carlo simulations in proton therapy

For radiation therapy, it is crucial to ensure that the delivered dose matches the planned dose. Errors in the dose calculations done in the treatment planning system (TPS), treatment delivery errors, other software bugs or data corruption during transfer might lead to significant differences between predicted and delivered doses. As such, patient specific quality assurance (QA) of dose distributions, through experimental validation of individual fields, is necessary. These measurement based approaches, however, are performed with 2D detectors, with limited resolution and in a water phantom. Moreover, they are work intensive and often impose a bottleneck to treatment efficiency. In this work, we investigated the potential to replace measurement-based approach with a simulation-based patient specific QA using a Monte Carlo (MC) code as independent dose calculation engine in combination with treatment log files. Our developed QA platform is composed of a web interface, servers and computation scripts, and is capable to autonomously launch simulations, identify and report dosimetric inconsistencies. To validate the beam model of independent MC engine, in-water simulations of mono-energetic layers and 30 SOBP-type dose distributions were performed. Average Gamma passing ratio 99 ± 0.5% for criteria 2%/2 mm was observed. To demonstrate feasibility of the proposed approach, 10 clinical cases such as head and neck, intracranial indications and craniospinal axis, were retrospectively evaluated via the QA platform. The results obtained via QA platform were compared to QA results obtained by measurement-based approach. This comparison demonstrated consistency between the methods, while the proposed approach significantly reduced in-room time required for QA procedures

Analysis of multi-layer ERBS spectra

A systematic way of analysis of multi-layer electron Rutherford backscattering spectra is described. The approach uses fitting in terms of physical meaningful parameters. Simultaneous analysis then becomes possible for spectra taken at different incoming energies and measurement geometries. Examples are given to demonstrate the level of detail that can be resolved by this technique.This work was realized with support from CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico – Brazil and the Australian Research Council

<b>Características físico-químicas de aguardentes produzidas artesanalmente na região do vale do taquari no rio grande do sul<br>Physicochemical properties of spirits produced artisanally in the Region of Vale do Taquari in Rio Grande do Sul </b>

<p align="justify"> A aguardente elaborada artesanalmente resulta num produto fi nal com características próprias e diferenciadas, porém, devido à falta de controle do processo muitas vezes não atendem aos parâmetros legais vigentes. Assim, este trabalho teve por objetivo avaliar a qualidade e comparar a composição química de aguardentes de canade- açúcar envelhecidas e sem envelhecer produzidas artesanalmente na Região do Vale do Taquari no Rio Grande do Sul. Foram analisados os teores de etanol, acidez volátil, compostos fenólicos, cobre, acetona, aldeídos, ésteres, alcoóis superiores totais e metanol, além dos alcoóis secbutílico e n-butílico de 15 amostras produzidas na região. Os resultados indicaram que 60% das amostras estavam em desacordo com algum dos padrões de identidade e qualidade estabelecidos pela legislação brasileira. Além disso, as altas concentrações de cobre e aldeídos em algumas amostras comprometem a qualidade da bebida e representam um risco à saúde dos consumidores da região. A partir dos resultados obtidos verifi cou-se a necessidade de adoção de estratégias de apoio tecnológico que capacitem os produtores da Região do Vale do Taquari no Rio Grande do Sul, de modo a ampliar a atividade agroindustrial e melhorar a competitividade desses pequenos produtores. </p&gt