PubMed1975
In judging the risk incurred by persons professionally exposed to radiation, there is at present a more distinct tendency towards consideration of somatic effects - as e.g. somatic "crossing over", accidents of development, induction of cancer; thus more attention is paid to individual risk. For assessment of this radiation risk, the organ doses in question must be known; they can be estimated by means of the ascertained tissue-air-ratios, if the field of stray radiation from the X-ray equipment is known. To obtain data for statements with regard to the radiation load on the examiner during radioscopies with a therapy simulator, it was necessary to determine the stray radiation field of the X-ray apparatus. Therefore, using an Alderson-Man-phantom, the angular distribution of the local dose rate were measured at a tube voltage of 84 kV. The skin irradiation fields had dimensions of 25 cm2, 100 cm2, and 400 cm2 at the distances 50 cm, 100 cm, 150 cm, and 200 cm of the ionization chamber from the central ray. The measurements were performed on levels of 90 cm, 130 cm, and 160 cm above the floor. Some additional measurements aimed at a more exact investigation of the dependency of scattered radiation upon the tube voltage, the area of the radiation field, the distance from the central ray, and the height above the floor. The attenuation capacity of a light radioprotective apron (0.25 mm lead equivalence) was also determined. It turned out that, at a tube voltage of 84 kV, the apron still was passed by about 3.6% of the hitting stray radiation. The present measurements yield important indications of the best possible locations of the examiner during radioscopy. A practical example is given showing how to assess the radiation load on single organs; the results show that the examiner is exposed to a gonadal load of about 2 mR and to a load of about 17 mR on the crystalline lenses, while engaged in preparative roentgenologic measures for intrauterine transfusions.