Geometric calibration of a double-line X-ray cone-beam tomography system

This dataset correspond to the raw data and measurements presented in the article "Geometric calibration of a double-line X-ray cone-beam tomography system". In this study, an existing single-line calibration method is extended to the case of a double-line X-ray tomograph, based only on the geometrical relation between the different components, and using a simplified calibration phantom. The methodology is tested on the new double tomograph system at INSA Lyon. Walnuts are used as testing phantoms due to their natural irregularity and outstanding internal texture under X-rays. Two scanning scenarios are selected to represent the wide range of possible geometries that the system can resolve. The first test, referred to as NXGP04, corresponds to an assembly of walnuts inside a container, scanned at a voxel size of 111 μm, and a geometric magnification (i.e., the ratio between SDD and SOD) of 2.7. The second test, referred to as NXGP05, constitutes a scan of a single walnut using a voxel size of 28 μm and a geometric magnification of 10.7. For a given test, all the geometric parameters (i.e., SOD and SDD), as well as the scanning parameters (e.g., voltage and exposure time) are set equally for both lines. Calibration phantoms are used to measure the geometry of the system for each test. They consist of a set of 7 metallic spheres attached to a foam board arranged along a line. For the test NXGP04, the spheres have 2.5 mm in diameter and are placed using a spacing of 20 mm, while for the test NXGP05, the spheres have 0.8 mm in diameter and spacing of 8.75 mm. In both cases, the size of the spheres in the detectors is such that more than 700 pixels are used to determine their centre, which increases the sensitivity of the calculation.