Conceptus dose from two state-of-the-art CT scanners.

Two phantoms, constructed from plastic and water and appropriately proportioned to simulate the female pelvis, were used in the evaluation of the dose delivered to a conceptus from two widely used computed tomographic (CT) scanners. Doses were measured along the central axis and surface of each phantom while scanning 25 contiguous 1-cm sections. Ionization chambers were used for data acquisition. Methods for correcting for partial volume effects inside the chambers are examined. Formulas for calculating the dose to the conceptus in a wide variety of possible situations are presented. These data may be used to guide management of pregnant patients who require or have had CT examinations.