'Focused workshop on Region of Interest X-ray Computed Tomography' held on 17-20 November 2015 at Elettra (Trieste, Italy)

To satisfy the heterogeneous needs of X-ray CT users, flexible solutions are required both from the hardware and software point of view. The use of synchrotrons and microfocus X-ray sources present complementary approaches being characterized by different properties in terms of achievable spatial resolution, field of view and image contrast. The main aim of this event was to bring together experimentalists, mathematicians and computing scientists and explore this specific topic in Computed Tomography (CT) data collection and reconstruction. This focused meeting hosted a small group of mathematicians and computational scientists at the Elettra Sincrotrone Trieste laboratory (Italy) with the aim to study in detail the Region-Of-Interest (ROI) problem in CT. This workshop has been organized as a follow-up of the Lorentz 2015 workshop focusing our attention on the specific topic of ROI-CT. In fact, ROI-CT reconstructed images are often corrupted by artefacts that, in some cases, mask part of the information contained in the image itself. Find solutions require a full comprehension of the origin of these artefacts. Micro-CT data were analyzed on site having the ability to acquire the data at varying contrast and spatial resolutions and on different instruments. The whole object has been imaged at medium spatial resolution by using a conventional CT instrument based on a microfocus source (http://www.elettra.trieste.it/li ) and then a selected ROI has been selected and imaged at higher spatial resolution. A similar ghtsources/labs-and-services/tomolab/tomolab.html approach has been adopted at the SYRMEP beamline of Elettra ( ) where a micro-CT http://www.elettra.trieste.it/elettra-beamlines/syrmep.html instrument allowing to work at higher spatial resolution and based on a synchrotron source is available. A mixed approach employing the conventional and synchrotron sources for the same object has been also explored.