The pioneers of X-ray imaging soon realized that X-rays could damage the body. Indeed, high-power X-rays precisely focused are used to destroy malignant tissue. Because of the dangers of radioactivity of all kinds, strict safety precautions are observed by those working with irradiating equipment. The staff wear protective aprons and headgear, or retire behind a screen, when the X-ray source is switched on; otherwise the accumulated effects of taking dozens of pictures, each one relatively harmless in itself, could be dangerous.
From the patient’s viewpoint, radiation doses are minimized during all radiological examinations, and care is taken to screen or protect sensitive tissues such as the ovaries or testes. Doctors try to reserve radiological examinations for cases of clear necessity as part of their responsibility for minimizing their patients’ exposure to the rays. X-ray examination of the unborn child is nowadays avoided in all but very exceptional circumstances, because X-rays may have deleterious effects on embryological and foetal development. X-rays during pregnancy have now been all but replaced by ultrasound scans.