Scheme of tomographic examination of the chest: 1 - X-ray tube ; 2 - cassette.
Tomography (synonym for layered X-ray examination ) is an X-ray examination method that allows to obtain X-rays of individual layers of the studied area. Tomography is performed using a special apparatus - a tomograph or tomographic attachment, which is attached to modern x-ray machines. To obtain tomograms, an x-ray tube and an x-ray film cassette (fig) connected in a rigid system are set in opposite directions. In connection with the movement of the X-ray tube, most of the details reflecting the area under study become fuzzy, as if “smeared out”, and only the details that are in the plane of the axis of movement of the tube and cassette are clearly visible. By changing the level of the axis of movement, it is possible to produce X-rays of various layers. Depending on the purpose of the study, layer-by-layer images are produced after 2; 1; 0.5 cm. Tomography is made in various projections: straight, lateral, oblique, axial (using a special, so-called transverse, tomograph).
Tomography significantly complements the results of conventional radiography , allowing you to identify significant details that are not defined on radiographs due to the total display on the planar image of the entire thickness of the studied area.
Tomography is often used to detect infiltrates, cavities , abscesses, tumor foci in the lungs, enlarged lymph nodes in the mediastinum and other pathological changes in the chest organs, as well as destructive foci in the bones. Tomography provides substantial assistance in the diagnosis of diseases of the larynx, sinuses , bones and joints (especially the skull and spine ).
See also tomofluorography .