Measurement accuracy of CT systems: The importance of calibration phantoms
Fig 5
A profile line of 50 pixels (25 pixels for SOMATOM Force scans) was placed over the outer edge of the ruby ball in each CT scan in the 2D view to determine the gradient of the grey values. (A) The slope of the fit curves (Rodbard fit) with a grey value between 60 and 140 (grey box) was determined for the profile lines and shown as an example for a scan in the high-resolution micro-CT (11 µm voxel size, central position) in red and the oversize micro-CT (20 µm voxel size, central position) in green. (B) Comparison of the slope of the profile lines (B). In the micro-CTs, scans with smaller voxel sizes have steeper profile lines. The steepest profile lines were measured in the high-resolution micro-CT scans.