Relationships between Regional Radiation Doses and Cognitive Decline in Children Treated with Cranio-Spinal Irradiation for Posterior Fossa Tumors

Pediatric posterior fossa tumor (PFT) survivors who have been treated with cranial radiation therapy often suffer from cognitive impairments that might relate to IQ decline. Radiotherapy (RT) distinctly affects brain regions involved in different cognitive functions. However, the relative contribution of regional irradiation to the different cognitive impairments still remains unclear. We investigated the relationships between the changes in different cognitive scores and radiation dose distribution in 30 children treated for a PFT. Our exploratory analysis was based on a principal component analysis (PCA) and an ordinary least square regression approach. The use of a PCA was an innovative way to cluster correlated irradiated regions due to similar radiation therapy protocols across patients. Our results suggest an association between working memory decline and a high dose (equivalent uniform dose, EUD) delivered to the orbitofrontal regions, whereas the decline of processing speed seemed more related to EUD in the temporal lobes and posterior fossa. To identify regional effects of RT on cognitive functions may help to propose a rehabilitation program adapted to the risk of cognitive impairment

Contrôle de qualité et optimisation de l'acquisition des données en imagerie multimodale pour la radiothérapie externe

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocSudocFranceF

Variations anatomiques en cours d'irradiation conformationnelle pour cancer de la prostate (quantification, impact dosimétrique et clinique, rationnel pour une radiothérapie guidée par l'image)

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Integration et validation d'un système de compensateurs dans une chaine de traitement de radiothérapie par modulation d'intensité

PARIS-BIUP (751062107) / SudocSudocFranceF

Etude des techniques de régularisation en radiothérapie conformationnelle avec modulation d'intensité et évaluation quantitative des distributions de dose optimales

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

MAESTRO: outcomes of an innovative European project dedicated to Radiation therapy

International audienceUne préoccupation fondamentale en radiothérapie est de délivrer à la tumeur une dose aussi précise et conformationnelle que possible tout en épargnant les tissus sains. Dans cette optique, le projet intégré européen MAESTRO (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology) a développé des solutions concrètes innovantes pour les différentes phases du processus de radiothérapie. MAESTRO, dont les travaux se sont échelonnés de mai 2004 à octobre 2009, a été coordonné par le CEA (France) et comportait 25 partenaires, dont 7 français, comprenant des instituts de recherche, des centres de radiothérapie, des industriels. Nous présenterons les réalisations Maestro les plus proches de l'application clinique. Cette présentation est faite au nom des partenaires MAESTRO

Expérience française sur la radiothérapie guidée par l'image : contrôle de qualité, dose additionnelle délivrée, protocoles de radiothérapie guidée par l'image et premières données cliniques. [French experience on IGRT: quality control, additional delivered dose, IGRT protocols and first clinical results].

International audienc

A phantom study of the accuracy of CT, MR and PET image registrations with a block matching-based algorithm

International audiencePURPOSE: The aim of the present study was to quantitatively assess the performance of a block matching-based automatic registration algorithm integrated within the commercial treatment planning system designated ISOgray from Dosisoft. The accuracy of the process was evaluated by a phantom study on computed tomography (CT), magnetic resonance (MR) and positron emission tomography (PET) images. MATERIALS AND METHODS: Two phantoms were used to carry out this study: the cylindrical Jaszczak phantom and the anthropomorphic Liqui-Phil Head Phantom (the Phantom Laboratory), containing fillable spheres. External fiducial markers were used to quantify the accuracy of 41 CT/CT, MR/CT and PET/CT automatic registrations with images of the rotated and tilted phantoms. RESULTS: The study first showed that a cylindrical phantom was not adapted for the evaluation of the performance of a block matching-based registration software. Secondly, the Liqui-Phil Head Phantom study showed that the algorithm was able to perform automatic registrations of CT/CT and MR/CT images with differences of up to 40 degrees in phantom rotation and of up to 20-30 degrees for PET/CT with accuracy below the image voxel size. CONCLUSION: The study showed that the block matching-based automatic registration software under investigation was robust, reliable and yielded very satisfactory results. This phantom-based test can be integrated into a periodical quality assurance process and used for any commissioning of image registration software for radiation therapy

Evaluation of an atlas-based automatic segmentation software for the delineation of brain organs at risk in a radiation therapy clinical context

International audienceBACKGROUND AND PURPOSE: Conformal radiation therapy techniques require the delineation of volumes of interest, a time-consuming and operator-dependent task. In this work, we aimed to evaluate the potential interest of an atlas-based automatic segmentation software (ABAS) of brain organs at risk (OAR), when used under our clinical conditions. MATERIALS AND METHODS: Automatic and manual segmentations of the eyes, optic nerves, optic chiasm, pituitary gland, brain stem and cerebellum of 11 patients on T1-weighted magnetic resonance, 3-mm thick slice images were compared using the Dice similarity coefficient (DSC). The sensitivity and specificity of the ABAS were also computed and analysed from a radiotherapy point of view by splitting the ROC (Receiver Operating Characteristic) space into four sub-regions. RESULTS: Automatic segmentation of OAR was achieved in 7-8 min. Excellent agreement was obtained between automatic and manual delineations for organs exceeding 7 cm3: the DSC was greater than 0.8. For smaller structures, the DSC was lower than 0.41. CONCLUSIONS: These tests demonstrated that this ABAS is a robust and reliable tool for automatic delineation of large structures under clinical conditions in our daily practice, even though the small structures must continue to be delineated manually by an expert