Image distortion and magnification of 3 digital CCD cephalometric systems

Abstract

Objective: The magnification and distortion of images made from scanning and nonscanning CCD cephalometric systems was evaluated.

Study design: Acrylic box and dry human skull phantoms were imaged using a conventional cephalostat, the nonscanning Kodak 8000C, the horizontally scanning GE/Instrumentarium OC100D, and the vertically scanning Sirona OrthophosDS. True linear and angular measurements of the phantoms were made using a coordinate measuring system and the Hitachi MercuRay cone beam system. The accuracy of linear and angular measurements was assessed, as were magnification and distortion, where appropriate.

Results: Statistically significant differences between linear and angular measurements were found for almost all measurements for both phantoms. In general, the conventional cephalostat and Sirona OrthophosDS systems produced the greatest magnification and distortion while the GE/Instrumentarium OC 100D and Kodak 8000C systems, the least.

Conclusions: Measurement differences related to the beam geometries of these systems could not be predicted a priori. Unaccounted for, these differences could result in clinically significant consequences.