A multi-resolution image reconstruction method in X-ray computed tomography

International audienceWe propose a multiresolution X-ray imaging method designed for non-destructive testing/ evaluation (NDT/NDE) applications which can also be used for small animal imaging studies. Two sets of projections taken at different magnifications are combined and a multiresolution image is reconstructed. A geometrical relation is introduced in order to combine properly the two sets of data and the processing using wavelet transforms is described. The accuracy of the reconstruction procedure is verified through a comparison to the standard filtered backprojection (FBP) algorithm on simulated data

Effets secondaires cutanéo-muqueux des traitements anticancéreux

BREST-BU Médecine-Odontologie (290192102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

A multiresolution image reconstruction method in X-ray microCT

International audienceWe propose a method for multiresolution image reconstruction in X-ray micro computed tomography (microCT). It can have a variety of applications, from material characterization to small animal imaging studies. The main idea is to recover an overall image of the sample with a coarse resolution, and with a fine resolution for a region-of-interest (ROI). In a zoo-min CT type setup, two sets of data are used, taken at different magnifications ratios. They are combined with the help of an analytical relation and the reconstruction is an extension of the filtered back-projection (FBP) algorithm. We present results with simulated data, some performance aspects and a simple noise analysis

Multiresolution X-ray CT Imaging of Fiber Reinforced Composite Materials

International audienceWe present an X-ray CT imaging method adapted to complex samples such as fiber reinforced composites, for which different spatial resolutions are needed to resolve the structures at different size scales: the whole sample, groups of fibers, individual fibers and matrix material. We developed an efficient algorithm which uses two sets of tomographic data acquired in a zoom-in CT configuration and which outputs a bi-resolution image. The method was validated on simulated data and we present experimental results for two different samples

Experimental validation of a Monte Carlo model to predict EPID images for online verification in radiotherapy

International audienceOne proposed method this past decade for online verification of dose delivery in radiotherapy consists in comparing images acquired using Electronic Portal Imaging Devices (EPIDs) with predicted dose images computed using Monte Carlo simulations. The objective of this study is twofold: first, to demonstrate that the Monte Carlo simulation code PENELOPE is suitable to compute reliably portal images, and second, to validate a portal prediction model against measurements. Portal images were acquired with a fluoroscopic EPID and a Saturne 43 accelerator (12 MV photons) for different field sizes, both with and without a 30×30×30 cm 3 water phantom in the beam. Monte Carlo simulations of the accelerator and the EPID were performed using the Monte Carlo simulation code PENELOPE. Several EPID models were tested, differing by the level of complexity in the geometry. This study shows that the EPID signal can be realistically predicted by a simple three-layer model, including two layers to describe the fluorescent screen and an additional water layer to take into account optical photons backscattering within the EPID structure. Using this model, 2D gamma index values less than 1 were obtained for 96% of the pixels for fields of 10×10 cm 2 or less and for 90% of the pixels for larger field sizes. These results exhibit that the EPID model determined in this study allows computing accurately portal images of open fields, with or without an object in the beam

Validation of a Monte Carlo prediction model for portal images using PENELOPE

International audienceIn external beam radiotherapy, dosimetric verification is usually performed by comparing dose images provided by EPIDs with predicted images computed using Monte Carlo (MC) simulations. The goal of the present study is to develop a portal prediction model with the MC code PENELOPE and validate it against experiment. Experimental images were acquired at 12 MV using a Saturne 43 accelerator and a fluoroscopic Lynx2D EPID (SDD = 150 cm), for 4´4, 10´10 and 15´15 cm² open fields, and both without and with a 30´30´30 cm3 water phantom in the beam. The accelerator and the EPID were simulated with PENELOPE. Two EPID models were implemented, one describing in details the geometry and the other being a simplified model, composed of three layers (copper, GOS and water). The water layer simulated the backscatter within the EPID and its thickness had to be adjusted. The best EPID model was found to be the simplified model including an 8 cm thick backscatter compartment. This model was then used to compute portal images with and without thewater phantom in the beam and the simulated and acquired images were compared using the g-analysis. g-index values less than 1 were obtained for 96% of the pixels for fields of 10x10 cm² or less and for 90% of the pixels for larger field sizes. These results exhibit that a simple MC EPID model allows predicting accurately portal images for open fields, with and without object in the beam, and that PENELOPE is a reliable tool for this purpose

Immune checkpoint inhibitors in patients aged 80 or older with advanced non-small cell lung cancer or melanoma: a real-life multicentre study

International audienceBackground Data regarding characteristics, safety and survival outcomes of patients aged 80 or older treated with immune checkpoint inhibitors (ICI) in routine oncology practice are limited. Materials and methods We retrospectively collected data of patients aged 80 and older with advanced non-small cell lung cancer (NSCLC) or melanoma treated with anti-PD1, anti-PD-L1 or anti-CTLA-4 regardless of the treatment line, in 14 institutions, between January 2014 and June 2017. Progression-free survival (PFS) and overall survival (OS) were estimated with the Kaplan Meier method. Toxicity was assessed according to CTCAE 5.0. Multivariate analyses were performed with the Cox model. Results Eighty-two patients were included (36 with NSCLC, 45 with melanoma). Their median age was 82 years (range 80-93). Nivolumab and pembrolizumab were mainly used. In the NSCLC group, median PFS and OS were 2.3 months (95%CI 1.8-6.1) and 8.8 months (95%CI 5.5-18.1), respectively. In the melanoma group, median PFS and OS were 10.2 months (95%CI 4.5-20.0) and 24.5 months (95%CI 14.1-NR), respectively. The albumin level was found to be independently associated with a better OS in both groups. Grade 3-4 toxicities occurred in 15 patients (18.5%). One patient died from ICI-induced pulmonary toxicity. Conclusion Our study findings suggest that treatment with ICI in elderly patients with NSCLC and melanoma has a risk-benefit ratio that supports its use. However, we report in this cohort that one in five patients has a grade 3-4 IRAEs leading to treatment discontinuation. Geriatric assessment prior to initiation of therapy and during therapy should be routine in patients aged 80 years and older

Laparoscopy‐assisted immediate vaginal reconstruction with a vertical pedicled deep inferior epigastric perforator flap for primary melanoma of the vagina

International audienceThe vagina is a rare site for primary melanoma. Here, we report on a case of laparoscopy-assisted immediate vaginal reconstruction with vertical pedicled deep inferior epigastric perforator flap