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Technique at radiography
Radiography - sacroiliitis
Radiography - spinal changes
Technique at conventional radiography

A radiograph is a picture of the body part examined produced by transmission of X-rays through the region to the imaging medium. This is today usually digital e.g. a phosphorus-plate. The X-rays reaching the plate generate excitated electrons in the plate. The plate is subsequently read digitally and the data are transferred to an imaging processor (computer) for final image elaboration. Digital images can be evaluated on a workstation and can by the use of PACS (Picture Archival and Communication System) be archived and distributed digitally. The images can thereby be available in several places simultaneously.

 

The images below show examples of equipment for radiography. The image formation is based on the passage of X-rays through the body to a digital medium e.g. a phosphorus containing plate, which subsequently is read in the digital reader.

 

The image formation is based on the X-rays, which are not absorbed in the body and therefore reach the imaging medium.

The absorption of X-rays through the body depends on the tissues they pass (tissue density and thickness) and the X-ray quality. Bone surfaces having a high X-ray absorption appear light, and air, which does not absorb radiation, is black. Fatty tissue has lower density (is darker) than other soft tissues. Fat occurs in the bone marrow between bone trabeculae and contributes to the clear delineation of internal bone trabeculae. They present white due to their relative high density against the dark fatty tissue, e.g. in the heel bone (calcaneus).

 

Lateral radiograph of the calcaneus showing a clear delineation of the bone trabeculae (white arrow) due to the presence of contrasting fatty tissue in the bone marrow. The image in addition shows new bone formation at the attachment of tendons to bone (black arrows).

 
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