The aim of this work was to determine mean absorbed doses to the unborn child in common conventional X-ray and computed tomography (CT) examinations and to find an approach for estimating foetal dose based on data registered in the Radiological Information System/Picture Archive and Communication System (RIS/PACS). The kerma-area product (KAP) and CT dose index (CTDI(vol)) in common examinations were registered using a human-shaped female dosimetry phantom. Foetal doses, D(f), were measured using thermoluminescent dosimeters placed inside the phantom and compared with calculated values. Measured foetal doses were given in relation to the KAP and the CTDI(vol) values, respectively. Conversion factor D(f)/KAP varies between 0.01 and 3.8 mGy/Gycm(2), depending on primary beam position, foetus age and beam quality (tube voltage and filtration). Conversion factors D(f)/CTDI(vol) are in the range 0.02 - 1.2 mGy/mGy, in which the foetus is outside or within the primary beam. We conclude that dose conversion factors based on KAP or CTDI(vol) values automatically generated by the RIS/PACS system can be used for rapid estimations of foetal dose for common examination techniques.