Tomographie par émission de positons et détection en coïncidence (TEDC) et recalage d'images de simulation virtuelle par tomodensitométrie. Impact sur la planification de la radiothérapie conformationnelle des cancers bronchiques non à petites cellules

Phantom study on radiotherapy planning using PET/CT--delineation of GTV by evaluating SUV

We assessed the usefulness of PET/CT images to determine the target volume in radiotherapy planning by evaluating the standardized uptake value (SUV). We evaluated the imaging conditions and image-reconstruction conditions of PET/CT useful for treatment planning by collecting (18)F-FDG images of acrylic spheres (10-48 mm in diameter) in a phantom. The (18)F-FDG concentration in the spheres was 10-fold higher than that of the phantom. The contours were delineated according to the SUV by the threshold and regions of interest (ROI) methods. Comparisons of two- and three-dimensional (2D and 3D) acquisition images indicated that the sharpness and quantitative qualities of the sphere boundaries were better in the former than in the latter. In the extraction of outlines using the SUV, outlines obtained at an SUV of 40-50% of the maximum agreed well with the actual acrylic sphere size. 2D acquisition images are more suitable for delineating target volume contours, although 3D acquisition images are more popular in diagnostic imaging. An SUV of 40-50% of the maximum is suggested to be appropriate for GTV contouring of sphere tumors with homogenously distributed (18)F-FDG.

Complications aiguës et tardives des irradiations thoraciques

Radiotherapy of lung cancer is often complexe because of several organs at risk such as lung, heart, esophagus or spinal cord. An accurate balance needs to be defined between the necessities to reach a local control and to limit the risks of toxicities for each of them. Several parameters were significantly correlated with radiation induced lung toxicities (V13, V20, 30, Mean Dose) and esophagitis (V40 to V60). However no parameters are clearly defined for heart toxicities. The large number of parameters described for lung and esophagus highlights the necessity to perform an overall analysis of the DVHs that could be possible by using Nomal Tissue Complication Probability models.

Traitement des tumeurs de l'apex: un modèle de stratégie multimodale dans les cancers bronchiques localement évolués

Superior sulcus tumors have been individualized among other non-small cell lung cancers because of their characteristic clinical presentation in connection with their local extension to the chest wall and the brachial plexus. For a long time considered as marginally resectable, superior sulcus tumors have been treated since the early 1960's, with a combined approach including preoperative radiotherapy and curative-intent surgery. Surgical resection includes both thoracic, cervical and neurosurgical approach, and aims at obtaining complete resection, which has been identified as a determining prognostic factor in most reported series. Two recent phase II trials showed the benefit, both regarding resectability and local control rates, and survival of combined therapeutic strategies including induction platinum-based chemoradiation, extensive surgical resection, and adjuvant chemotherapy. Adjuvant radiotherapy is not recommended at the time, but needs to be re-evaluated regarding its recent technical optimisation. Similarly to other locally advanced non-small cell lung cancers, exclusive chemoradiation is the standard treatment of unresectable superior sulcus tumors. In this way, radiotherapy has shown to offer a prolonged analgesia in more than 75% of cases, and is associated with concurrent or sequential chemotherapy, with comparable results to those observed in stage III lung cancer. These developments make superior sulcus tumors a therapeutic model for locally advanced non-small cell lung cancer, whereby the benefit of combined multimodal strategies including induction chemoradiation and surgical resection are currently evaluated in phase III trials.