Shading
A shadow (also radio opacity ) is a lighter and a brightening (radiolucency) a dark area on an X-ray image . The reason is the different radiopacity of tissue types.
Both terms are usually used for brightnesses that deviate from normal - but occasionally also for non-pathological findings .
In the early days of X-rays in medicine, fluorescent screens were used instead of X-ray films . These reacted to a lot of X-rays with more (brighter) light and to fewer X-rays with less (darker) light.
Areas that appeared darker than expected were called shaded because the X-ray light was apparently shaded by an object or the like. The lighter areas where X-rays penetrated better than expected were called brightened .
The situation is different with the X-ray films used later. Like any other negative film , these films are blackened more (i.e. darker) by more light (here X-rays) and less blackened (i.e. lighter) by less light.
Since the terms from the era of the fluorescent screen have been retained, there is an apparent paradox . So, an area on the X-ray film that is lighter than it should be is called shaded , and an area that is darker than it should be is called lightened .
Web links
Individual evidence
- ^ HJ Mentzel, Radiography . Friedrich Schiller University Jena. Retrieved April 12, 2015.