Radiological examination is a kind of imaging examination, which refers to the method of using X-rays to carry out imaging examination, such as going to the hospital to do X-rays, fluoroscopy, CT, barium meal of the digestive tract, breast molybdenum target, DSA, PETCT and so on belong to this kind of examination. Radiological examination of the human body has a certain amount of radiation, many people hear radiological examination extremely panic, but in fact because of the disease occasionally do a radiological examination is not a problem, each kind of instrument radiation exposure dose is far below the national regulations of the safety value. In some patients, radiological examinations cannot be replaced by other examination methods, such as head diseases, lung diseases, and diseases of the skeletal system.