[Audit on pelvimetry at a polyvalent radiology department].

Purpose: Study of the dose absorbed by the fetus during CT pelvimetry.

Material And Methods: Twenty consecutive pelvimetries on pregnant women showed the mean fetal location in regard of the maternal pelvic skeleton (retrospective study). Then, thermoluminescent radiation detectors were put in the antropomorph phantom slices, in housing correspondent to the fetal's volume. The location of this volume has been determined by the first study. Two different CT units were tested.

Results: In case of cephalic presentation, the maximum fetal dose was 3 mGy. In case of pelvic presentation, because of an additional frontal topogram, the dose reached 3,3 to 3,6 mGy.

Conclusion: We recommend: 1) reduction of parameters (120kV and 100mAs) for "normal" women; using other parameters for larger women; interval follow-up to evaluate results using these parameters; 2) tilting the bisciatic plane of section so to avoid direct exposure to the fetus; 3) limitation to 25 cm for the lateral scout; suppression of the routine frontal scout in case of pelvic presentation.