Morphometric analysis of image distortion with rotational panoramic radiography.

We studied the image distortion of spherical objects that occurred during rotational panoramic radiography. We measured the magnification of height, width, perimeter and area, and calculated the circularity index to quantify the distortion. Spherical objects of different diameters were projected on the film. A complex relationship was found between the position and the horizontal magnification for each anatomical region. The object's size influenced the horizontal magnification to a considerable extent. The greatest changes in circularity occurred at the midline. This morphological distortion was caused by non-symmetrical projection during the scanning of these spherical objects, which resulted from the continuous changes in the scanning velocity and the position of the x-ray beam. This result suggests a complex distortion of the inner structures of macroscopic objects.