Validation of GATE 6.1 for targeted radiotherapy of metastic melanoma using 131I-labeled benzamide

International audienceThe GATE 6.1 Monte Carlo simulation platform based on the GEANT4 toolkit is in constant improvement for dosimetric calculations. Here, we explore its use for calculating internal absorbed dose distribution in mice for the treatment of malignant melanoma after injection of a new specific radiopharmaceutical labeled with iodine 131. We estimate the dosimetric accuracy of GATE 6.1, by calculating first S values and by comparing them and absorbed doses to organswith EGSnrc for a digital mouse phantom and a CT scan based mouse phantom

Grid technology for biomedical applications

International audienceThe deployment of biomedical applications in a grid environment has started about three years ago in several European projects and national ini-tiatives. These applications have demonstrated that the grid paradigm was rele-vant to the needs of the biomedical community. They have also highlighted that this community had very specific requirements on middleware and needed fur-ther structuring in large collaborations in order to participate to the deployment of grid infrastructures in the coming years. In this paper, we propose several ar-eas where grid technology can today improve research and healthcare. A cru-cial issue is to maximize the cross fertilization among projects in the perspec-tive of an environment where data of medical interest can be stored and made easily available to the different actors of healthcare, the physicians, the health-care centres and administrations, and of course the citizens

Coccydynia

Coccydynia is a term that refers to pain in the region of the coccyx. Most cases are associated with abnormal mobility of the coccyx which may trigger a chronic inflammatory process leading to degeneration of this structure. In some patients this instability may be detected on dynamic radiographs. Nonsurgical management remains the gold standard treatment for coccydynia, consisting of decreased sitting, seat cushioning, coccygeal massage, stretching, manipulation, local injection of steroids or anesthetics, and postural adjustments. Those patients who fail these conservative modalities may potentially benefit from coccygectomy. However, surgical intervention is typically reserved for patients with evidence of advanced coccygeal instability (e.g., subluxation or hypermobility) or spicule formation, as this population appears to exhibit the greatest improvement postoperatively

Modifier l'environnement didactique dans le domaine de la production d'écrits : l'introduction des TICE est-elle efficace pour des apprentis ?

The CAP Building Trade students are, for the most part, from Adapted General Education Professional Training and 3rd Vocational Discovery 6 hour class backgrounds, or are high school dropouts. Generally speaking, they face continuing difficulties and show little or no interest in activities in French, especially written tasks. How then does one adapt his or her teaching style to help these students succeed?This dissertation allows to pinpoint who these students are, why they experience these types of difficulties, and identifies educational and instructional methods adapted to these specific types of learners which can help them become higher achievers in writing.Les apprentis en CAP Bâtiment, issus pour la plupart de Sections d’Enseignement Général et Professionnel Adapté, 3e Découverte Professionnelle 6 heures ou ayant été en situation de décrochage scolaire, qui pour la plupart éprouvent des difficultés persistantes, ne s’impliquent pas ou s’impliquent peu dans les activités de français et tiennent souvent un discours « négatif » sur les activités d’écriture. Comment alors modifier adapter les pratiques d’enseignement pour réduire les difficultés de ces élèves ?Ce mémoire permet d’identifier qui sont ces élèves, quelle est la nature de leurs difficultés et quels sont les moyens pédagogiques et didactiques qui peuvent réduire les obstacles et agir comme des facilitateurs pour permettre d’améliorer leurs compétences et leurs connaissances dans le domaine de l’écriture

Validation of the GATE Monte Carlo simulation platform for modelling a CsI(Tl) scintillation camera dedicated to small animal imaging

Monte Carlo simulations are increasingly used in scintigraphic imaging to model imaging systems and to develop and assess tomographic reconstruction algorithms and correction methods for improved image quantitation. GATE (GEANT 4 Application for Tomographic Emission) is a new Monte Carlo simulation platform based on GEANT4 dedicated to nuclear imaging applications. This paper describes the GATE simulation of a prototype of scintillation camera dedicated to small animal imaging and consisting of a CsI(Tl) crystal array coupled to a position sensitive photomultiplier tube. The relevance of GATE to model the camera prototype was assessed by comparing simulated 99mTc point spread functions, energy spectra, sensitivities, scatter fractions and image of a capillary phantom with the corresponding experimental measurements. Results showed an excellent agreement between simulated and experimental data: experimental spatial resolutions were predicted with an error less than 100 mu m. The difference between experimental and simulated system sensitivities for different source-to-collimator distances was within 2%. Simulated and experimental scatter fractions in a [98-182 keV] energy window differed by less than 2% for sources located in water. Simulated and experimental energy spectra agreed very well between 40 and 180 keV. These results demonstrate the ability and flexibility of GATE for simulating original detector designs. The main weakness of GATE concerns the long computation time it requires: this issue is currently under investigation by the GEANT4 and the GATE collaboration

Etudes dosimétriques des sources I125I^{125} utilisant les simulations Monte-Carlo GATE sur grille de calcul EGEE

PCSV, présenté par C. Thiam, transparents sur site, résuméLa méthode de calcul Monte Carlo est reconnue aujourd'hui comme l'algorithme pouvant modéliser au plus près les phénomènes physiques liés aux dépôts d'énergie dans un milieu. Il est donc intéressent d'utiliser cette méthode dans la planification de traitement du cancer par rayonnement, les systèmes de planification de traitement (TPS) existant étant limités dans la précision des calculs pour certains cas spécifiques. Dans cette approche nous nous intéressons à la validation du code de calcul Monte Carlo GATE (basses énergies) pour les applications dosimétriques en physique médicale. Nous avons modélisé avec GATE des modèles de sources I125 sous forme de grains couramment utilisées en curiethérapie (les grains 2301 B.M.I., Symmetra UroMed/Bebig). Les caractéristiques de ces sources ont été simulées en respectant les extrémités soudées, la distribution radioactive, les matériaux et le rayonnement des spectres d'énergies. Pour effectuer nos calculs de dose, nous nous sommes référé aux travaux du groupe de travail « Task Group 43 » de l'American Association of Physicists in Medicine (A.A.P.M.) datant de 1995 et mis à jour en 2004. Les fonctions de dose radiale et d'anisotropie ainsi que la constante de débit de dose définissant les caractéristiques dosimétriques de ces sources ont été calculées avec différentes versions de GATE. Les résultats obtenus, en comparaison avec d'autres codes Monte Carlo (PTRAN, MCTP) ou mesures par thermoluminescence (TLD), sont en bon accord avec les valeurs publiées dans la littérature et par les travaux du TG 43. Les Simulations Monte Carlo GATE nécessitent en général plusieurs heures de calculs. Afin de réduire ces temps, nos simulations GATE ont été parallélisées sur une infrastructure de grille de calcul mise en place par le projet EGEE (Enabling Grids for E-sciencE). Les résultats obtenus par cette technique sont très prometteurs. Le temps nécessaire au calcul dans le cas des applications dosimétriques a été réduit d'un facteur 3

GATE simulation for medical physics with genius Web portal

présenté par C. ThiamPCSV team of the LPC laboratory in Clermont-Ferrand is involved in the deployment of biomedical applications on the grid architecture. One of these applications deals with the deployment of GATE (Geant4 Application for Tomographic Emission) for medical physics application. The aim of the developments actually performed is to enable an application of the GATE platform in clinical routine. However, this perspective is only possible if the computing time and user time are highly reduced. The new grid architecture, developed within the framework of the European project Enabling Grid for E-sciencE (EGEE) is there to answer this requirement. The use of the grid resources must be transparent easy and rapid for the medical physicists. For this perpose, we adapted the GENIUS web portal in order to facilitate the GATE simulations planning on the grid. We will present a demonstration of the GENIUS portal which integrates all the functionalities of EGEE: to create, to submit and manage GATE jobs on the grid architecture. Our GATE activities for dosimetry application entered in to direct phase of evaluation by the cancer treatment center of Clermont Ferrand (Centre Jean perrin).A work station is currently available in this center to test the use of GATE application on the grid through GENIUS. This portal will allow in a long term to use GATE application in brachytherapy and radiotherapy treatment planning using medical data (medical images, DICOM, binary data dose calculation in the heterogeneous mediums) and to analyze the results obtained in visual form. Other functionalities are under development and will make possible to register medical data on grid storages elements and to manage them. However, these data must be anonymised before their recording on the grid. Their access via the GENIUS portal must be made safe and fast (compared simulation computing time). In order to be sure that the medical data are accessible for calculations, their replication on various storage element (SE) should be possible. The grid services give the possibility of managing this information in a free way and transparently. Operations of data handling and catalogues on the grid are ensured by the Replica Manager system which integrates all tools making it possible to manage data on the grid. The computing grid give promising results and meet a definite need: reach acceptable computing time for a future use of Monte Carlo simulations for treatment planning in brachytherapy and radiotherapy

Les grilles de calcul au service de la physique médicale

présenté par C.O. Thiam, proceedings sous forme de CDLes Simulations Monte Carlo GATE en radiothérapie nécessitent plusieurs heures de calculs. En effet, un résultat précis ne peut être obtenu qu'en générant beaucoup d'événements. Nous étudions donc les capacités des grilles de calcul notamment en terme de réduction des temps de calculs, et les services qu'elles offrent pour une utilisation future en milieu médical. Cette infrastructure, s'inscrit dans le cadre du projet européen EGEE. Ce projet consiste à mutualiser des ressources réparties sur différentes sites afin de pouvoir accéder à de la puissance de calcul, à des données partagées et de bénéficier d'une continuité de service