Fig. 3
From: Evaluation of gantry speed on image quality and imaging dose for 4D cone-beam CT acquisition
Different slices of the Catphan’s modules used for image quality evaluation. a A bar pattern module of increasing spatial frequency (lp/cm), used for determining spatial resolution of the protocols. b A low contrast module used in calculating CNR of the various protocols. c A homogeneous module used in determining uniformity, with four ROI (anterior, posterior, right, and left) equidistant from a centrally located ROI. d A sensitometry module containing materials of known electron density, used in the calculating HU difference from baseline