Anion redox as a means to ferive layered manganese oxychalcogenides with exotic intergrowth structures

Topochemistry enables step-by-step conversions of solid-state materials often leading to metastable structures that retain initial structural motifs. Recent advances in this field revealed many examples where relatively bulky anionic constituents were actively involved in redox reactions during (de)intercalation processes. Such reactions are often accompanied by anion-anion bond formation, which heralds possibilities to design novel structure types disparate from known precursors, in a controlled manner. Here we present the multistep conversion of layered oxychalcogenides Sr2MnO2Cu1.5Ch2 (Ch = S, Se) into Cu-deintercalated phases where antifluorite type [Cu1.5Ch2]2.5- slabs collapsed into two-dimensional arrays of chalcogen dimers. The collapse of the chalcogenide layers on deintercalation led to various stacking types of Sr2MnO2Ch2 slabs, which formed polychalcogenide structures unattainable by conventional high-temperature syntheses. Anion-redox topochemistry is demonstrated to be of interest not only for electrochemical applications but also as a means to design complex layered architectures

Intensity-Based Deformable Registration: Introduction and Overview

International audienceThe purpose of this chapter is to give an introduction to intensity-based deformable image registration and present a brief overview of the state-of-the-art. First, we lay out the basic principles of deformable registration. Next, the key components of the registration framework are discussed in detail and two popular algorithms for deformable registration are described as an example. We review past studies on respiratory motion estimation for radiotherapy. Finally, we briefly list useful open-source software packages and available image and validation data sets for deformable registration of the thora

Advances in deformable image registration of thoracic 4D CT

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Deformable image registration with automated motion-mask extraction

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Keuhkot: a method for lung segmentation

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Open source tools for validation of deformable registration

International audienceDeformable image registration is of considerable interest to the radiation therapy community. It is considered a key enabling technology for applications such as adaptive radiotherapy, contour propagation in 4D CT images, atlas-based segmentation, breathing motion modeling, dose accumulation and many more. Deformable registration is slowly finding its way to commercial software packages. However, validation of the estimated deformation fields remains challenging because no ground truth is available. In general, validation of deformable registration relies on manually generated data, often in the form of hand-clicked landmarks or handdrawn contours. Obtaining such data is a laborious and time-consuming task. Strictly speaking, the resulting validation should be considered as partial, due to the high number of degrees of freedom of the system. In addition, the ill-posed nature of the problem implies the procedure needs to be repeated when dealing with images of different quality, nature or modality. Open-source and open-data concepts constitute an approach where source code and data are provided for free usage, within the limits of a defined agreement, and with a strong concern on users' feedback and participation. It has proved to be an efficient strategy to accelerate scientific advances in a difficult field, based on distributed and collaborative effort, in particular by enabling evaluation and comparison. Many initiatives exist for the application of validating deformable registration, several of which have had a considerable impact in the field. In this presentation, we will describe some open-source and open-data tools that have been proposed and used for validation of deformable image registration. We will review some freely available image processing toolkits (e.g. ITK, elastix), publicly accessible databases of annotated images (e.g. Dir-Lab, POPI), visualization freeware (e.g. VTK, Osirix, VV) and implementation contests or challenges (EMPIRE10). Advantages and limitations of each will also be discussed

In-room breathing motion estimation from limited projection views using a sliding deformation model

International audiencePurpose: To estimate in-room breathing motion from a limited number of 2D cone-beam projection images by deformably registering them to a phase of the planning 4DCT. Methods: Breathing motion was modelled using a piecewise continuous B-spline representation, allowing to preserve the sliding along the thoracic wall while limiting the degrees of freedom. The deformed target 3D image was subsequently used to generate Digitally Reconstructed Radiographs. Their normalised correlation coefficient with the measured projection images was computed in the 2D projection space but its derivatives were backprojected into the 3D space, avoiding the projection of the transform jacobian matrix which is computationally intractable. Results: The method was qualitatively evaluated on a lung cancer patient treated in the Léon Bérard Cancer Center. The deformed planning CT visually matched well the reconstructed cone-beam CT. Quantification was done on 2 patients of the DIR-labs database with different breathing amplitudes. Forty cone-beam projection images were simulated using the end-exhale phase of the planning 4DCT and the detector positions of a real middle field of view cone-beam acquisition (off-centered). The end-inhale phase was deformed to match these simulated projections. The Target Registration Error decreased from 3.89 mm to 1.14 mm for the first patient and from 15 mm to 4.21 mm for the second. For the first patient, the 3D/3D registration of the reconstructed cone-beam CT obtained with the same set of simulated projections was comparatively worse (1.46 mm), due to view aliasing artefacts. Conclusions: 2D/3D deformable registration seems to improve the quality of in-room breathing motion estimation from a limited number of view