Applications and advances in X-ray Computed Tomography (CT) for dendrochronology
Over the past 10 years, X-ray Computed Tomography (CT) has been increasingly applied to dendrochronological research. This technique provides 3D images of the internal structure of objects, allowing non-invasive access to tree rings in cultural heritage objects that are often inaccessible from the outside. Here, we will present the state-of-the-art of tomographic X-ray imaging for the application to dendrochronology. We will give a comprehensive overview of how X-ray computed tomography is used to answer dendrochronological questions of historical objects (panel paintings, sculptures and furniture), and will discuss the hardware and software requirements to enable dendrochronological investigation on the resulting reconstructed images. Furthermore, we will highlight the limitations for the application of X-ray CT to dendrochronological research, such as the material composition of the object, object size and image resolution. These topics will be illustrated with examples of our work, including our recent breakthrough in X-ray imaging for dendrochronology of large wooden objects, which is based on line-trajectory scanning. This method exploits the shape of the tree rings to visualise them with limited data, so that the object only needs to move sideways as opposed to a full rotation in regular CT. We will close with a discussion of future applications of X-ray imaging to cultural heritage made of wood.