Focal plane tomography’s development began in the 1930s as a means of reducing the problem of superimposition of structures which is inherent to projectional radiography.

[3] Focal plane tomography generally uses mechanical movement of an X-ray source and film in unison to generate a tomogram using the principles of projective geometry.

[4] Synchronizing the movement of the radiation source and detector which are situated in the opposite direction from each other causes structures which are not in the focal plane being studied to blur out.

The technique advanced through the mid-twentieth century however, steadily producing sharper images, and with a greater ability to vary the thickness of the cross-section being examined.

[7] It is still used in some centres for visualising the kidney during an intravenous urogram (IVU),[8] though it too is being supplanted by CT.[9][10] Panoramic radiography is the only common tomographic examination still in use.