Reduction of patient dose in x-ray examination

In the roentgenography the patient is exposed with the skin dose of about 200mR, while in the fluoroscopy with the dose from 2 to 7R/min.Among the radiation hazards induced by X-ray examination the incidence of genetic mutation and cancer is of importance.When the nation wide Japanese gonad dose caused by X-ray examination is counted by referring with data of child expectancy, the genetically significant dose, GSD, which is estimated 26.5mrem/y in 1970 is obtained. It is well known that the leukaemia is induced by irradiation to the bone marrow. Leukaemia significant dose which is counted by the similar way to that of the genetically significant dose is thus estimated 169mrem/y in 1969.Both of the genetically significant dose and the leukaemia significant dose caused by X-ray examination are much more high than those caused by the debris of the explosions of the atomic weapons and miscellaneous radiation source.In order to reduce the patient dose, the education or training of correct establishment of clinical judgement should be encouraged. Beam limitation in the X-ray examination is the most effective means to reduce the patient dose, in particular, gonad dose and bone marrow dose.