Three-dimensional imaging of flat natural and cultural heritage objects by a Compton scattering modality

Abstract

Characterization and interpretation of flat ancient material objects, such as those found in archaeology, paleoenvironments, paleontology, and cultural heritage, have remained a challenging task to perform by means of conventional x-ray tomography methods due to their anisotropic morphology and flattened geometry. To overcome the limitations of the mentioned methodologies for such samples, an imaging modality based on Compton scattering is proposed in this work. Classical x-ray tomography treats Compton scattering data as noise in the image formation process, while in Compton scattering tomography the conditions are set such that Compton data become the principal image contrasting agent. Under these conditions, we are able, first, to avoid relative rotations between the sample and the imaging setup, and second, to obtain three-dimensional data even when the object is supported by a dense material by exploiting backscattered photons. Mathematically this problem is addressed by means of a conical Radon transform and its inversion. The image formation process and object reconstruction model are presented. The feasibility of this methodology is supported by numerical simulations.

3D Compton scattering imaging with multiple scattering: analysis by FIO and contour reconstruction

“…It is also possible to consider interior sources, for instance via the insertion of radiotracers like in SPECT. Then considering collimated detectors, it is possible to model the scattered flux through conical radon transforms, see for instance [33,36]. However, in this work, we consider only systems with external sources.…”

The Development of Radon Transforms Associated to Compton Scatter Imaging Concepts

“…This class of Radon transform in R 3 , in the so-called compounded . From top to bottom: original phantom, direct inversion, inversion after normalizing values following z-axis, inversion after removing voxels located at edges of single reconstructions of dimensions 4×4×32 voxels, reprinted from [39] form, supports a remarkable imaging process known as Compton scatter SPECT imaging which can provide directly the three dimensional image of the interior of an object by a standard gamma camera functioning in a fixed spatial position. The absence of rotational motion characteristic of standard SPECT imaging represents a major advantage resulting from the exploitation of scattered gamma rays for imaging purpose.…”

“…They may be fed into the inversion formula (see [15] to reconstruct the object electron density. As we shall see, the second procedure with back scattering turns out to be relevant for cultural heritage research imaging [38,39], (see section 6).…”

Microchemical Imaging of Oil Paint Composition and Degradation: State-of-the-Art and Future Prospects

“…As a follow-up, each spectrum in the dataset can be expressed (i.e., modeled) as a linear combination of the calculated latent variables, returning chemically relevant weight matrices. A more detailed review of methods to perform dimensionality reduction to obtain chemical maps can be found in (Guerrero Prado et al 2017).…”