Visualisation of Foreign Bodies of Low Radio-Opacity

From the radiologists's point of view foreign bodies are divided into two types: radio-opaque and non-opaque or translucent. Some years ago these two groups were easily defined. All metallic foreign bodies, projectiles, needles, coins, etc., were opaque, and most of the non-metal foreign bodies were radio-translucent and could not be demonstrated by X rays. Nowadays, in the “age of plastics” and other synthetic substances, it is becoming increasingly difficult to say which substances are opaque and which are not. The clinician should therefore make it his principle to refer any case of suspected foreign body, anywhere in the body, for X-ray examination regardless of its density.