A method for correcting for errors produced by variable magnification in three-dimensional tuned-aperture computed tomography

Objectives: To develop and test a method for correcting tomosynthetic misre gistration caused by variation in projective magnification. Methods: A tooth from a monkey was radiographed from various angles and dis tances using a solid-state sensor to which a plastic spacer with a wire fra me was attached, The position of the tooth was fixed relative to both the f rame and the sensor. Information derived from the frame's shadow was used t o produce a series of tomosynthetic slices using tuned-aperture computed to mography (TACT(R)). One series was corrected for magnification errors and t he other was not. Corresponding slices from each series were compared. Results: The corrected slice exhibited much less artifactual blur than its uncorrected counterpart. Linear traces through corresponding portions of th ese slice images demonstrated discrepancies in homologous dimensions attrib utable to systematic variations in projective magnification. Conclusions: Correcting for differences in projective magnification reduces both misregistration and scaling artifacts in tomosynthetically reconstruc ted volumes.