Patent ID: 6917668

Claim:
In a digitized tomosynthesis method for obtaining 3D volumetric imaging of an object in which a ray of energy from a source travels through the object to impinge on an energy sensor having a determined pixel size defining an image plane and in which the object is rotated about an axis that intersects the energy sensor whereby an image is acquired by the energy sensor at successive rotational positions of the object, the improvement according to which a coordinate of the source position with respect to the sensor is determined, comprising the steps of: placing a first registration marker that is substantially opaque to the energy on a first location proximate the energy sensor and along the object's axis of rotation; obtaining a first shadow image corresponding to the first registration marker by exposing the first registration marker to energy from the energy source; placing a second registration marker that is substantially opaque to the energy on a calibration post disposing the second registration marker at a location distal from the energy sensor spaced at a predetermined distance from said first location along the object's axis of rotation; obtaining a second shadow image of the calibration post corresponding to the second registration marker by exposing the second registration marker to energy from the energy source; determining the distance from the source to the energy sensor at the intersection of the axis with the energy sensor; determining the height of the second marker; determining the central coordinates of the first and second marker shadows; computing the azimuth; computing the elevation angle; and using the elevation angle and azimuth to compute the coordinate of the source position with respect to the sensor.