[en] Objectives: study of dosimetry impact of optimization actions in pediatrics CT scanning, after analysis and standardization of the practices in the service. results: A first analysis of six months of activity at the end of 2006 showed that the protocols, responding to the recommendations of the French society of pediatrics and prenatal imaging (S.F.I.P.P.) were poorly followed in the service: the practices were heterogeneous, and the average values of dose.(D.L.P.) length product were superior to the recommendations. At the end of 2007, an awareness action towards the personnel was realised and the protocols of acquisition established at the scanner implementation were modified. The analysis, at half 2008, following the pattern of 2006 showed a harmonization of practices in the service, a strong reduction of average value of the dose.length product (D.L.P.) by acquisition (50% in thorax CT scanning) and the systematic respect of the recommendations of the S.F.I.P.P.. conclusions: after evaluation of the service practices, the awareness of the personnel and the modification of protocols allowed to reduce strongly the doses delivered in paediatrics CT scanning (up to 50%, while keeping an image quality in accordance with the diagnosis. (N.C.)