Editing Tomography (section)

==History==
[[Focal plane tomography]] was developed in the 1930s by the radiologist [[Alessandro Vallebona]], and proved useful in reducing the problem of superimposition of structures in [[projectional radiography]].

In a 1953 article in the medical journal [[Chest (journal)|''Chest'']], B. Pollak of the [[Fort William Sanatorium]] described the use of planography, another term for tomography.<ref>{{cite journal
 |title      = Experiences with Planography
 |first      = B.
 |last       = Pollak
 |journal    = Chest
 |doi        = 10.1378/chest.24.6.663
 |pmid = 13107564
 |date       = December 1953
 |volume     = 24
 |issue      = 6
 |pages      = 663–669
 |url        = http://chestjournal.chestpubs.org/content/24/6/663.abstract
 |archive-url = https://archive.today/20130414135338/http://chestjournal.chestpubs.org/content/24/6/663.abstract
 |url-status = dead
 |archive-date = 2013-04-14
 |issn       = 0012-3692
 |access-date = July 10, 2011
}}</ref>

Focal plane tomography remained the conventional form of tomography until being largely replaced by mainly [[computed tomography]] in the late 1970s.<ref>{{cite book|last=Littleton|first=J.T.|title=A History of the Radiological Sciences|publisher=[[American Roentgen Ray Society]]|chapter-url=http://www.arrs.org/publications/HRS/diagnosis/RCI_D_c15.pdf|access-date=29 November 2014|chapter=Conventional Tomography}}</ref> Focal plane tomography uses the fact that the focal plane appears sharper, while structures in other planes appear blurred. By moving an X-ray source and the film in opposite directions during the exposure, and modifying the direction and extent of the movement, operators can select different focal planes which contain the structures of interest.