Applications of X-rays
The X-ray photographs or radiographs used in medical practice are made by allowing X-rays to pass through parts of the body and on to a photographic film. X-rays are used in hospitals also in the treatment of malignant growths, as it is found that cancer cells can be destroyed by this means. Nevertheless, great care is always taken to avoid unwanted doses of this radiation, as these have a harmful effect on normal cells also which often does not become apparent until some years afterwards. Before this danger was realized many of the early experimenters became very ill after working with X-rays, and a number lost their lives. Nowadays X- Ray tubes are always surrounded by lead shields to absorb stray radiation.In industry X-ray photographs are used to reveal hidden flaws III metal castings
and welded joints (Fig. 44.9). Fig. 44.10 shows how X-radiography is used to detect alterations which have been made to works of art. The technique owes its success to the fact that pigments containing lead compounds absorb X-rays more strongly than those which contain lighter elements.