Alignment and resolution studies of a MARS scanner

TL;DR

This paper discusses the alignment procedures and resolution estimations for the MARS x-ray scanner, crucial for accurate tomographic reconstruction of samples using cone-beam geometry.

Contribution

It introduces specific alignment methods and evaluates the spatial resolution achievable with the MARS scanner, improving reconstruction accuracy.

Findings

Alignment procedures improve reconstruction quality.

Estimated spatial resolution for reconstructed images.

Geometrical correction methods enhance tomography accuracy.

Abstract

The MARS scanner is designed for the x-ray spectroscopic study of samples with the aid of computer tomography methods. Computer tomography allows the reconstruction of slices of an investigated sample using a set of shadow projections obtained for different angles. Projections in the MARS scanner are produced using a cone x-ray beam geometry. Correct reconstruction in this scheme requires precise knowledge of several geometrical parameters of a tomograph, such as displacement of a rotation axis, x-ray source position with respect to a camera, and camera inclinations. Use of inaccurate parameters leads to a poor sample reconstruction. Non-ideal positioning of camera, x-ray source and cylindrical rotating frame (gantry) itself on which these parts are located, leads to the need for tomograph alignment. In this note we describe the alignment procedure that was used to get different geometrical corrections for the reconstruction. Also, several different estimations of the final spatial resolution for reconstructed images are presented.