Tomography is a branch of imaging which produces an image called a tomogram which shows a single plane of an object in very specific detail.
The tomographic examination is designed to image only the anatomy that lies in the plane of interest, while blurring structures on either side of that plane. This brings us the sub heading linear tomography.

Linear tomography is the most basic form of tomography which permits the acquisition of x-ray relative to any plane that is parallel to the x-ray table. The main purpose of linear tomography is to blur out objects lying above and below the plane and for object lying in the plane to be properly imaged. This method improves the contrast resolution

the principle of linear tomography is pretty simple. During linear tomography, the x-ray tube is attached mechanically to the image receptor and moves in one direction, while the image receptor moves in the opposite direction. An imaginary pivot point called the fulcrum is the point where the tube and the image receptor move. The position of the fulcrum determines the object plane, and only those anatomical structures lying within this plane are clearly imaged, thus blurring out every other another anatomy below or above the object plane.

In terms of application, linear tomography is used to view parts of the body that have uniform absorption for x-rays (the abdomen is a clear example). It is applied in nephrotomography, which is linear tomography of the kidneys with a relatively large tomographic angle. It basically blurs out any organ blocking the kidneys. Linear tomography is also applied in IVP. The major disadvantage of linear tomography or tomography for that matter is increased patient dose.