1 Zusammenfassung 3 Résumé 5 Curriculum Vitae 43 Abstract large air cavities in the hemithorax after removal of the lung. During radiotherapy, I showed that the volume of the cavity will decrease progressively over time in an unpredictable way. This cavity will disappear within days to months and thus will affect surrounding anatomy and modify the dose distribution. This study demonstrated that these modifications were more or less pronounced depending on the radiotherapy technique used.

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... ed photon radiotherapy techniques appeared to be robust when small anatomical changes occurred, which was not the case for PT. For PT small changes of tissue density resulted in drastic dose distribution changes. Therefore adaptive radiotherapy will be required in order to take into account anatomy modifications. In order to optimize this process, image registration will be required in order to propagate the structures from one CT to an-other. In order to perform this step automatically, a colaboration with the Swiss Federal Institute of Technology Zurich was done to developp a new non-rigid automatic registration. Therefore, we compared inter-and intraobserver variability to the automatic resigstration. This study showed that inter-and intraobserver deviations were greater or similar to the variance of the population formed by deviations in contouring for the elastic region in a very large portion of the target volume. Therefore, this non rigid registration could be a big assess for adaptive RT. In conclusion, I showed that modulated RT was able to reduce the treatment toxicity in comparison to 3DCRT and enhanced tumor control. The dose distribution was further improved with VMAT. Nevertheless, no difference was observed in respect to overall survival due to the high rate of distant metastasis. PT was able to further reduce the dose to all organs at risks in comparison to any photon techniques. However, PT was the most sensitive treatment to modifications of the anatomy, emphasizing the need for adaptive RT and replanning. A non-rigid registration algorithm was also developped. Using this tool, efficient adaptive radiotherapy can be realized by propagating structures of interest between datasets. Epidemiology of malignant pleural mesothelioma