Analysis of Image Magnification in X-Ray fan beam Computed Tomography

X-ray computed tomography (CT) is a non-destructive measurement method that allows inspection into both external and internal geometry of a scanned sample. This work is mainly concerned with industrial X-ray CT and its 2D image reconstruction parameters. The purpose of our study was to investigate how image magnification in 2D X-ray CT is influenced by the object position for a 50.5 mm x 50.5 mm cuboid. Using a standard definition of magnification, equations were derived to enable geometrical magnification to be determined from its position and vice versa knowing the diameter and machine parameters. Experimental data are compared and observed with regard to geometrical magnification. Results from experimental data showed a strong correlation between geometrical magnification and image magnification obtained from the reconstructed CT image. Derived sizes of cuboid from magnification were more consistent horizontally with geometrical magnification than vertically.