DIAGNOSIS OF CANCER – INTERNAL CANCERS (X-RAYS USING CONTRAST METHODS)
The internal structure of many organs can be made to show up on X-rays by using contrast materials. These are usually substances which are much denser than the normal tissue (that is, let far fewer X-rays through). Barium is such a substance. If you swallow a liquid barium mixture, it coats and fills the gullet and stomach. Later on, the small intestine will be lined by the barium as it passes through. Any ulcers or growths then show up as dark irregularities against the white of the barium lining these organs. If something is pushing on, say, the stomach from the outside, this will also be seen — the white barium inside the stomach shows whether its shape and position are normal. Fizzy substances can also be swallowed to produce contrast. In this case the contrast is provided by a less dense substance—air. The air looks black and when used in combination with barium provides a ‘double contrast’. A similar mixture can be put into the rectum by enema to outline the large intestine (colon).
Other contrast methods involve the injection of very dense liquids (often iodine-based) into the bloodstream. X-rays taken immediately after injection show up the blood vessels themselves as white lines (this is called angiography). We can see whether the blood vessels are partly or completely blocked or displaced from their normal position. Sometimes we can show up extra blood vessels which could be feeding a cancer growth.
*66/40/1*
Random Posts
Tags: Cancer