High spatial resolution inorganic scintillator detector for high energy X-ray beam at small field irradiation

International audiencePurpose: Small fielddosimetry for radiotherapy is one of the major challenges due to the size of most dosimeters,e.g. sufficient spatial resolution, accurate dose distribution and energy dependency of the detector. In this context, the purpose of this research is to develop a small size scintillating detector targeting small field dosimetry and compare its performance with other commercial detectors. Method: An inorganic scintillator detector (ISD) of about 200 μm outer diameter was developed and tested through different small fields dosimetric characterization under high energy photons (6 MV and 15 MV) delivered by an Elekta Linear Accelerator (LINAC). PDD and beam profile measurements were compared using dosimeters from PTW namely, microdiamond and PinPoint 3D detector. A background fiber method has been considered to quantifyand eliminate the minimal Cerenkov effect from the total optical signal magnitude. Measurements were performed inside a water phantom under IAEA Technical reports series recommendations (IAEA TRS 381 and TRS 483). Results:Small fields ranging from 3 x 3 cm2, down to 0.5 x 0.5 cm2 were sequentiallymeasured using the ISD and commercial dosimeters, and a good agreement was obtained among all measurements. The result also shows that, scintillating detector has good repeatabilityand reproducibility of the output signal with maximum deviation of 0.26% and 0.5% respectively. The Full Width Half Maximum (FWHM) was measured 0.55 cm for the smallest available square size field of 0.5 x 0.5 cm2, where the discrepancy of 0.05 cm is dueto the scattering effects inside the water and convolution effect between field and detector geometries. Percentage Depth Dose (PDD) factor dependence variation with water depth exhibits nearly the same behavior for all tested detectors. The ISD allows to perform dose measurements at a very high accuracy from low (50 cGy/min) to high dose rates (800 cGy/min) and found to be independent of dose rate variation. The detection system also showed an excellent linearity with dose; hence calibration was easily achieved. Conclusions: The developed detector can be used to accurately measure the delivered dose at small field during the treatment of small volume tumors. The author’s measurement shows that despite using a non-water equivalent detector, the detector can be a powerful candidate for beam characterization and quality assurance in e.g., radiosurgery, Intensity Modulated Radiotherapy (IMRT), and brachytherapy. Our detector can provide real-time dose measurement and good spatial resolution with immediate readout, simplicity, flexibility, and robustness

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Selective Simulated Annealing for Large Scale Airspace Congestion Mitigation

This paper presents a methodology to minimize the airspace congestion of aircraft trajectories based on slot allocation techniques. The traffic assignment problem is modeled as a combinatorial optimization problem for which a selective simulated annealing has been developed. Based on the congestion encountered by each aircraft in the airspace, this metaheuristic selects and changes the time of departure of the most critical flights in order to target the most relevant aircraft. The main objective of this approach is to minimize the aircraft speed vector disorder. The proposed algorithm was implemented and tested on simulated trajectories generated with real flight plans on a day of traffic over French airspace with 8800 flights

Exploiting spatio-temporal partial separability of large-scale airspaces

International audienceThis paper addresses large-scale flight planning via a divide-and-conquer technique that exploits the partial separability feature of the problem. 4D-interaction between flights is used to cluster the flights, and these clusters are then exploited to improve the optimization process. Preliminary computational experiments on the French airspace demonstrate the natural separability of air traffic and yield promising computational improvement for flight planning thanks to the clustering

Air Traffic Complexity Map based on Linear Dynamical Systems

International audienceThis paper presents a new air traffic complexity metric based on linear dy-namical systems, of which goal is to quantify the air traffic control difficulty. Previous works have shown that the structure and organization of air traffic are important factors in the perception of the complexity of an air traffic situation, but they usually were not able to explicitly address any pattern organization. The new metric, by identifying the organization properties of trajectories in a traffic pattern, captures some of the key factors involved in ATC complexity. The key idea of this work is to find a linear dynamical system which fits a vector field as closely as possible to the observations given by the aircraft positions and speeds. This approach produces an aggregate complexity metric that enables to identify high (low) complexity regions of airspace and compare their relative complexity. The metric is very adapted to compare different traffic situations for any scale (sector or country)

Impact de facteurs non acoustiques lors de tests d'écoute en laboratoire sur bruit aéroportuaire

International audienceIt is well known that acoustical factors explain only partly the human perception of aircraft noise. In order to truly understand annoyance ratings, acoustical and non-acoustical factors have to be taken into consideration, making it often complex to analyze studies that treat only one side of the issue. While field studies give a good insight of long-term annoyance in realistic living conditions, laboratory tests are commonly used as means to understand the impact of acoustic factors on noise annoyance and unpleasantness while usually smoothing inter individual differences. A French project (CIGALE) has set a goal of creating a frame of reference making it possible to include non-acoustical factors into laboratory studies. After an extensive field study and focus groups in the first part of the project resulting in six different profiles of residents, the second part comprises a vast laboratory test campaign in Toulouse and Paris region aiming at evaluating the impact of these profiles on the perception of two common acoustical factors in an ecological experimental setup. Overall more than 300 residents of the Toulouse Blagnac airport area and the Roissy Charles de Gaulle airport area participated in the CIGALE listening test. Participants were asked to read novels while seated in a listening room with a 3D audio simulation of an everyday soundscape. They were asked to rate their perception of four 15 minutes sequences randomly presented in which the number of aircraft flyovers and the maximum A-weighted sound level of each flyover were varied. Four different scales were used: task interference, mental effort, annoyance and comfort. The results support the hypothesis that profile type and noise sensitivity have an impact on annoyance ratings. The collected data also highlighted different response strategies regarding acoustical factors that need to be further investigated.Il est bien connu que les facteurs acoustiques n'expliquent qu'en partie la perception humaine du bruit des avions. Afin de bien comprendre une évaluation de gêne, les facteurs acoustiques et non acoustiques doivent être pris en compte, ce qui rend souvent complexe l'analyse d'études qui ne traitent qu'un aspect du problème. Alors que les études sur le terrain donnent un bon aperçu de la gêne à long terme dans des conditions de vie réalistes, les tests en laboratoire sont couramment utilisés pour comprendre l'impact des facteurs acoustiques sur la gêne et le désagrément liés au bruit, tout en atténuant généralement les différences interindividuelles. Un projet français (CIGALE) s'est fixé pour objectif de créer un référentiel permettant d'intégrer des facteurs non acoustiques dans les études en laboratoire. Après une vaste étude de terrain et des ateliers participatifs dans une première partie du projet aboutissant à six profils d'habitants différents, la seconde partie comprend une vaste campagne de tests en laboratoire à Toulouse et en région Parisienne visant à évaluer l'impact de ces profils sur la perception de deux facteurs acoustiques communs dans un montage expérimental écologique. Au total plus de 300 habitants de la région aéroportuaire de Toulouse Blagnac et de celle de Roissy Charles de Gaulle ont participé au test d'écoute CIGALE. Les participants ont été invités à lire des romans assis dans une salle d'écoute avec une simulation audio 3D d'un paysage sonore représentant une situation sonore rencontrée au quotidien. On leur a demandé d'évaluer leur perception de quatre séquences sonores de 15 minutes présentées au hasard dans lesquelles le nombre de survols d'aéronefs et le niveau sonore maximal de chaque survol étaient modifiés. Quatre échelles différentes ont été utilisées : l'interférence sur la tâche, l'effort mental, la gêne et le confort. Les résultats soutiennent l'hypothèse selon laquelle le type de profil et la sensibilité au bruit ont un impact sur les notations de gêne. Les données collectées ont également mis en évidence différentes stratégies de réponse concernant les facteurs acoustiques qui doivent être étudiées plus en détail

Network-wide robust and resilient metaheuristic trajectory optimization under thunderstorm disruptions

Network-wide robust and resilient trajectory planning is realized after the uncertainty propagations at trajectory and ATM levels. The inputs are the 4D trajectories with uncertainty and the delays applied to trajectories for network resiliency. The delays only shift the trajectories in time. The output is a set of algorithmic solutions for optimal trajectory selection under high complexity situations. According to the START concept, a proposed rerouting and/or rescheduling solution of the user-preferred flight plan is proposed to improve the resiliency and robustness of overall planning. The optimization process is realized using the simulated annealing metaheuristic to find the optimal rerouting and delays for each flight. The objective function of this optimization problem is a complexity metric function, based on Linear Dynamical System. This metric can consider uncertainty in the 4D trajectories. However, the computation of such metric requires extensive computation time. We proposed GPU-based concept to speed up the metric computation. We have found that the proposed GPU-based concept can potentially provide the desired performance and prove the computational viability of the START project. Nevertheless, our findings are not uniformly positive, as the reliance on single-precision arithmetic (on which current GPUs provide substantially higher throughput) seems to have proved more problematic than our previous expectation. The global air traffic complexity is reduced by a factor of six hundred from around 120 to 0.2. It corresponds to a better organization of the traffic. In fact, the complexity is mainly due to very few flights. The complexity reduction decreases the potential number of conflicts, because there are less converging air traffic situations

Towards a Stable and resilient ATM by integrating Robust airline operations into the network - Scientific Progress during the 1st year of START project.

Trajectory-based operations (TBO) is one of the cornerstones of a modernised air traffic-management (ATM) system. The TBO operation concept takes into account the trajectory of every aircraft during all phases of the flight and manages their interactions to achieve the optimum system outcome, with minimal deviation from the user requested flight trajectry, whenever possbile. However, as TBO is based on a constant exchange of information about trajectories between the ground and air systems, uncertainties inherent in the ATM system sometimes lead to a degradation of its performance when disruptions occur. The EU-funded START project aims to design, apply and verify optimised algorithms that will enable a robust ATM system not only for conventional air traffic but resilient in disrupted circumstances as well

Simulation Exercises for robust Flight dispatching solution under thunderstorm disruptions

The development, implementation and validation of optimisation algorithms for robust airline operations that result in stable and resilient Air Traffic Management (ATM) performance even in disturbed scenarios are the overall goals of START. This presentation focusses on the validation part. The validation of the START robust airline operations is performed by comparing the performance of a reference and a resilient scenario under disturbed and undisturbed conditions. The reference scenario is derived from the traffic demand for two days in 2018, June 7th and June 10th with strong convective weather phenomena. The resilient scenario is built on the reference scenario but is prepared for more frequent planning updates due to changing forecasts of capacity shortfalls mainly caused by weather impacts. Resiliency refers to the intrinsic ability of a system to adjust its functioning prior to, during, or following changes and disturbances. Within the validation trials performed, disturbances are included by means of convective weather areas which are handled as No-Fly-Zones (NFZ). Validation of the START results is performed threefold. First, reference and resilient scenarios are compared, mainly focussing on expected duration of overall conflict hours of aircraft with other aircraft and convective weather zones. Second, real life departure uncertainties are added by means of Monte-Carlo simulations with different distributions. Finally, scenarios are resolved with conflict resolution algorithms above FL150 as far as possible. The presentation gives an overview of the validation results, showing an overall low but stable benefit for the adapted aircraft fleet (Star Alliance) of the resilient scenario, with no negative effects for the global scenario

In-situ monitoring of wine volume, barrel mass, ullage pressure and dissolved oxygen for a better understanding of wine-barrel-cellar interactions

International audienceThe process of aging wine in oak barrels causes various mechanisms that modify wine quality. This study is devoted to understanding the gas and wine transfers that occur through the barrels depending on ambient conditions. Four barrels were instrumented in a cellar to monitor the liquid's height and evaporation rates, the ullage space pressure, the content of dissolved oxygen in the wine and the environmental conditions. The liquid wine progressed slowly through the wood and reached a stabilized position after approximately 100 days. Evaporation was initially very limited and then achieved an average rate of 20 mL per day after linearization of the moisture content profile. The evaporation rate was directly impacted by the cellar conditions. The negative pressure inside the barrels, created following the loss of wine, was also affected by the cellar conditions. Above a certain negative pressure, an air percolation threshold was reached, implying the rapid entry of air into the barrel