Oscar Acosta

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Sunday 1 December 2013

CV

Oscar Acosta is since 2010 an associate professor at the Signal and Image Processing Laboratory (LTSI - INSERM 1099),  ISTIC-University of Rennes 1, France. His main research activities are in image processing and computational methods for Prostate Cancer Radiotherapy in collaboration  with the Centre Eugene Marquis (PhD students).

He was awarded a Bachelors degree in Electrical Engineering in 1995 and subsequently a Master of Sciences degree in 1997 by the University of Andes in Bogotá, Colombia. During his first degree, he undertook an internship at the Neuropsychological Department of the Military Hospital in Bogotá, working on an Alzheimer’s Disease project, specifically, developing and testing an eye-tracking device. In 1997, he proceeded to Brest, France for a seven–month internship with the LATIM-ENSTB Laboratory, where he worked on retina image registration. In 1999, he was awarded a PhD scholarship, under a cooperation program between European and Latin American Institutes (ALFA BETA Biomedical Engineering Training Action), which took him back to France, this time to the LTSI-INSERM 1099 at the University of Rennes I. During his PhD he worked on the characterization of anatomical structures for the planning of vascular interventions.

Between 2005 and 2009 he worked as a research scientist for CSIRO in Australia . Based first at Westmead Hospital in Sydney (where he undertook the segmentation of paediatric CT images) and then at the Australian e-Health Research Centre in Brisbane where the focus of his research was in medical image processing for the study of Alzheimer’s Disease as being part of the biomedical imaging team. Between 2012 and 2016 he was member of the INSERM Scientific Specialized Commision  (CSS8). He is also taking part in the organization of  the IEEE EMBS International Summer School on Biomedical Imaging in St Jacut de la Mer, Emerald Coast.

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Wednesday 19 June 2013

Fusion d'images multimodales pour le ciblage en radiothérapie pour cancer de la prostate

La radiothérapie s’adresse à tous les stades de ce cancer, avec  une efficacité démontrée. Plusieurs stratégies ont été développées pour augmenter le contrôle local, en particulier en augmentant la dose d’irradiation. Cependant, l’augmentation de dose peut augmenter significativement les effets secondaires. Pour limiter la toxicité, plusieurs innovations techniques ont été développées afin d’améliorer la précision de la dose d’irradiation délivrée (radiothérapie par modulation d’intensité (IMRT), radiothérapie guidée par l’image (IGRT)). Il apparaît ainsi techniquement réalisable de délivrer une dose d’irradiation élevée dans la tumeur, à condition que celle-ci soit cependant clairement définie. La première étape standard de préparation de la radiothérapie implique une délinéation manuelle des structures anatomiques et de la cible tumorale prostatique sur une image de tomodensitométrie (TDM). Cette étape présente cependant des limites : les tissus mous apparaissent peu contrastés et la tumeur intra-prostatique est donc invisible....


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Tuesday 1 May 2012

Predictive Models of Toxicity

The estimation of the risk of toxicity has been traditionally based on the dose-volume histograms (DVH), which are bi-dimensional representations of the 3D dose images describing dose distributions as a function of only two variables, namely dose and volume.  Thanks to the DVH, it has been shown that correlation exists between dose, volume and rectal toxicity (Kupelian, Reddy et al. 2002)(Jackson, Skwarchuk et al. 2001)(Fiorino, Cozzarini et al. 2002)(Peeters, Hoogeman et al. 2006)(Huang, Pollack et al. 2002). For the bladder, however these correlations are very limited (Cheung, Tucker et al. 2007).  Based on these studies, the  French group « Groupe d’Études des Tumeurs Uro-Génitales » (GETUG) defined recommendations for the rectum and bladder “dose-volume” values, however corresponding to a small number of parameters (only 2 DVH threshold values for the rectum).

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Sunday 18 March 2012

Prostate Cancer Radiotherapy

french

Prostate cancer is one of the most commonly diagnosed male cancer with 190 000 new cases diagnosed  in the USA in 2010 (American Cancer Society) and 71 000 new cases in France in 2011 (INCa 2011). Radiation therapy is a commonly prescribed treatment for people diagnosed with prostate cancer which has proven to be efficient for tumour control (D'Amico, Whittington et al. 1998).  Several strategies have been recently developed to increase local control, particularly by increasing the dose of radiation in a context of clear dose-effect relationship (Beckendorf, Guerif et al. 2011)(Kuban, Tucker et al. 2008)(Zietman, DeSilvio et al. 2005). The goal is therefore to deliver higher doses to the clinical target, while minimising side effects to the surrounding organs at risk.  However, in prostate radiotherapy, rectal and urinary toxicity events are frequent with standard prescribed doses (70 Gy) and may even significantly increase for higher doses. Intensity Modulated Radiotherapy (IMRT) is the reference conformal radiotherapy technique which improves the therapeutic ratio in the dose delivery in the two kinds of structures (tumor/organ at risk (OAR) of toxicity). IMRT works through an inverse planning step which implies dose-volume constrains in the dose planning. In this context, the prediction of complications as a consequence of the OAR dose/volume irradiation is therefore crucial in decreasing toxicity.   IMRT combined with images acquired during the therapy to guide the radiation are improving today their precision and are able to reach precisely even moving targets (Image Guided Radiotherapy, IGRT). With the precision of the accelerators steadily growing (ARC-Therapy, cyberknife),  the opportunities for a better control by increasing the dose are open, but at expense of the risk of toxicity if efficient plannings and predictive models are not put in place.

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References

Prostate Cancer Radiotherapy

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Sunday 29 January 2012

Useful links literature

Useful links for bibliographic work:

Wednesday 11 January 2012

Colombia en Imagen

Manos a la obra!! Hands on.. San Agustin/Colombia

Saturday 18 June 2011

Traitement du cancer par radiothérapie

english >>

Le cancer constitue une des premières causes de mortalité dans le monde. En France, il touche environ 300 000 patients par an, dont les deux tiers seront traités par radiothérapie. La radiothérapie s’adresse à tous les stades du cancer, avec  une efficacité démontrée. Plusieurs stratégies ont été récemment développées pour  augmenter le contrôle local, en particulier en augmentant la dose d’irradiation. Cependant, lors d’une augmentation de dose les effets secondaires tardifs sur les organes à risque peuvent  augmenter significativement.  Pour limiter les événements de toxicité liés aux traitements par radiothérapie, plusieurs innovations  techniques ont été développées qui ont considérablement accru la précision de la dose d’irradiation délivrée (radiothérapie par modulation d’intensité (IMRT), radiothérapie guidée par l’image (IGRT) [de Crevoisier, 2009]).

Notre  travail autour de la radiothérapie guidée par l’image est  réalisé dans un cadre pluridisciplinaire (imagerie médicale, oncologie, sciences pour l’ingénieur).  La collaboration entre le LTSI INSERM U1099, le CHU de Rennes et le CRLCC Eugène Marquis, qui est l’un des 20 centres de recherche et de lutte contre le cancer, nous permet l’accès aux techniques les plus récentes de radiothérapie.  Ils sont dotés d’un matériel moderne et de haute technicité incluant des dispositifs d’imagerie (TDM, TEP, IRM) et de traitement (accélérateurs linéaires avec  CBCT et VMAT). 

  Travaux en cours:

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