Estimation and minimization of fetal absorbed dose: data from common radiographic examinations

A simple method of estimating fetal absorbed dose from common abdominal and pelvic radiographic examinations is presented. The method uses experimentally determined normalized depth dose curves (rad/Roentgen exposure free-in-air) and sonographic localization of the fetus. The method is useful for estimating fetal absorbed dose when a pregnant woman inadvertently undergoes a radiographic examination. However, its primary value is in minimizing fetal dose when a woman, known to be pregnant, must undergo a radiographic examination. Selection of proper projection and deliberate adjustment of bladder volume can result in significant fetal dose reduction particularly in the critical first trimester.