The purpose of linear tomography is for the clinical staff to make a sectional image through a specific body part. Consequently, structures in the focal plane appear sharper, while structures in other planes appear blurred. By modifying the direction and extent of the movement, operators can select different focal planes which contain the structures of interest.
PRINCIPLE
The principle of linear tomography is that the X-ray tube is moved in a straight line in one direction while the film moves in the opposite direction. As these shifts occur, the X-ray tube continues to emit radiation so that most structures in the part of the body under examination are blurred by motion. Only those objects lying in a plane coinciding with the pivot point of a line.
EQUIPMENT
Linear tomographic equipment is inexpensive and requires shorter exposure times than equipment requiring circular and hypocycloidal motion, however, there is a greater possibility that blurring and streaks will result.
The tomographic object plane contains the fulcrum. The imaginary pivot point from which the tube and the image receptor move. The tomography angle is the angle of movement that determines tomography section thickness. The principal advantage of tomography is its improved radiographic contrast.
