The present invention provides a method and system for determining the position
of the image of a target object or the position of the x-ray source in digital
tomosynthesis, as the x-ray source is moved relative to the object so as to obtain
multiple two-dimensional images of the object from multiple angles. At least one
marker, characterized by a simple and known image pattern, is disposed between
an x-ray source and a detector system. The shift in the image of the object, resulting
from the movement of the x-ray source during tomosynthesis, is calculated to a
desired resolution using the readily observable shift in the image of the marker.
The x-ray source may be translated along a plane parallel to the plane of the detector
system, or may be rotated about a fixed center.