Evaluation of image quality in tomographic imaging.
Modulation Transfer Functions (MTF) for tomographic imaging with linear, circular, hypocycloidal and spiral motion are given. They may be determined experimentally from tomographs of slits or line pair test patterns. In some cases calculation of the MTF from the blur pattern by Fourier transformation is possible. All tomographic MTFS show the same oscillatory behaviour as MTFS of focal spots, resulting in spurious structures and contours in the tomogram. A quantity named signal/spurios signal ratio (SSR) is introduced as a figure of merit. Effective exposure angles are determined from the MTF and compared with the commmonly used 'geometric' exposure angles which result from maximum tube elongations.
D014056:Tomography, X-Ray / Q000379:methods / Q000592:standards*