Numerical Approach of the Littoral Instability of Chalk Cliffs: Case of Grandes Dalles (The Large Flagstones)

The various situations representing coastal cliffs of Haute Normandy are tested on numerical models. The parameters taken into account are: the lithology of chalks and the presence or absence of fractures. It is a question of specifying the mechanical characteristics of chalk and the inside of the fractures. The chalk cliff of 80m height, with a vertical cliff face, is modeled in distinct elements in UDEC code. We consider initially the cliff with two layers, in dry and then in saturated state. Then, the cliff is taken with two layers; the chalk of Seaford constitutes the upper layer and the chalk of Lewes constitutes the lower layer, by introducing a fracture with a strong slope passing in the foot of the cliff and another time a fracture parallel with the cliff face

Multi-Atlas based Segmentation of Head and Neck CT Images using Active Contour

This paper presents the segmentation of bilateral parotid glands in the Head and Neck (H&N) CT images using an active contour based atlas registration. We compare segmentation results from three atlas selection strategies: (i) selection of "single-most-similar" atlas for each image to be segmented, (ii) fusion of segmentation results from multiple atlases using STAPLE, and (iii) fusion of segmentation results using majority voting. Among these three approaches, fusion using majority voting provided the best results. Finally, we present a detailed evaluation on a dataset of eight images (provided as a part of H&N auto segmentation challenge conducted in conjunction with MICCAI-2010 conference) using majority voting strategy

Combined concomitant boost radiotherapy and chemotherapy in stage III-IV head and neck carcinomas: A comparison of toxicity and treatment results with those observed after radiotherapy alone

Background Alteration of radiation therapy (RT) fractionation and the combination of chemotherapy (CT) with RT represent two predominant fields of current research in the treatment of head and neck carcinomas. To assess the potential integration of these two fields, a retrospective comparison of toxicity and treatment outcome was carried out in stage III-IV patients treated with a concomitant boost RT schedule with or without CT. Patients and methods Fifty-two patients were treated by RT alone and 35 by RT and CT. In the RT group, there were significantly fewer T3-4 tumors (56% vs. 88%, P=0.002) and higher proportion of planned neck dissections (35% vs. 14%, P=0.047). The planned total dose was 69.9 Gy delivered over 5.5 weeks. In 10 cases CT was given before RT and in 25 concomitantly with RT, either alone or with neoadjuvant and/or adjuvant CT. All patients but two had cisplatin-based (CDDP, 100 mg/m2) CT, associated in 28 patients with 5-fluorouracil (5-FU, 1000 mg/m2/24 h × 5). The median follow-up for the surviving patients was 21 and 31 months for the RT and RT-CT groups respectively. Results Grade 3-4 acute toxicity (RTOG) was observed in 73% and 86% of patients, and grade 3 dysphagia in 31% and 57% (P=0.02) respectively in the RT and RT-CT groups. The rates of grade 3-4 late complications were similar in the two groups (5% vs. 12%). At three years, actuarial loco-regional control (LRC) was 57% and 66% (P%0.66) and overall survival was 56% and 47% (P=0.99) in the RT and RT-CT groups respectively. Conclusion While acute toxicity was higher compared with RT alone, this accelerated RT schedule was feasible in association with 5-FU/CDDP, even administered concomitantly. Despite the significant proportion of more advanced disease in the RT-CT group, LRC was similar to that obtained by RT alone. Combinations of concomitant boost RT and chemotherapy merit further investigation in prospective trial