[Investigation of the exposure to radiation of the embryo/fetus in the course of radiographic examinations during pregnancy 1st communication: Tissue-air ratios for X-rays with tube voltages between 60 kV and 120 kV (author's transl)].

A relatively important radiation dose delivered to the embryo (fetus) is a decisive criterion, if interruption of pregnancy is considered for radiation-hygienic reasons. Several methods of assessment by calculation of the fetal exposition are discussed; in the last analysis, there are always needed the values of the relative depth doses or tissue-air ratios. The tissue-air ratios for the diagnostical X-ray qualities from 60 to 120 kV (total filtration 2.6 mm Al) were ascertained with the help of a water phantom. They are represented for layers from 0 to 20 cm by means of tables, and a comparison is made with data from the literature.