To determine the amount of displacement of a structure
noticed on an image when the tube of a dental X-ray
machine was shifted vertically and horizontally. In
addition, various intraoral images were combined with
dental panoramic images to determine the location of
structures. Our research is based on the parallax
technique which requires manipulation of horizontal
and vertical angulations of the X-ray tube. A metal
object is positioned on the buccal and palatal side of
the maxilla on the canine area of a skull. The X-ray
tube is shifted incrementally to obtain images on
phosphor plates. Subsequently, panaromic and occlusal
images were taken to assist in localization of the metal
object. To obtain a clear image shift of 2-3mm using
the parallax method, there must be an adequate
horizontal tube shift of approximately 30-35 degrees.
When images were used in combination of dental
panoramic images, it was found that the buccally
placed structures can be accurately located with the
periapical or occlusal images. However, the
displacement of images in the palatally placed
structures in panoramic imaging is not fully
appreciated with the principle of parallax method. Tube
movement of 30-35 degrees horizontally is needed for
a 2-3 mm image shift. To successfully localize a buccal
structure, a combination of either periapical or occlusal
images with a dental panoramic imaging can be
employed. However, this combination with panoramic
imaging is limited when looking at palatally placed
structures.