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Contrast
Materials opaque to X-rays can be introduced in hollow organs. This means that there is ‘contrast’ between the contents of the cavity and the wall. The cavity shows up as white in an X-ray image.
In some organs we can also introduce air or a gas so that it shows up as black.
Materials thus introduced for this purpose are called contrast media.
A contrast medium must satisfy certain criteria :
§It must be inert (non-reactive) non-toxic.
§It must not be absorbed or retained by the body.
§It must be easily excreted.
§
Key Points :
Contrast can be created artificially, by ‘contrast media’.
A contrast medium must be safe!