By appearance of computed tomography technology, there were increase of it`s application in CT scan experiments and researches. Given the high rate transmitted energy in this methods. It is essential to provide methods to decrease patient doses. There will be also need to introduce more accurate methods to estimate and effective chest doses in CT-Scan between adualt and children. In this method we have used of simulating code MCNPX2.6 to calculate effective doses. In this plan, we have benefited of GE Light Speed 16 Slice scanner in order to perform CT scan. Given the high rate transmitted energy in this methods. It is essential to provide methods to decrease patient doses. There will be also need to introduce more accurate methods to estimate and effective chest doses in CT-Scan between adualt and children. In this method we have used of simulating code MCNPX2.6 to calculate effective doses. In this plan, we have benefited of GE Light Speed 16 Slice scanner in order to perform CT scan. All the simulation scanner elements were calculated. In correspondence with produced X_rays beam values of both calculated and simulated CTDI were being tested and trustified. In this study fantom PMMA with 32cm diameter and 16cm diameter respectively for adualt and children was used. Calculation was performed in center and for 12 o`clock position for both simulation and real states. To convert CT doses index quant CTDI vol We have benefited from conversion index 0.017 for five age category among children and adualts. Our observation confirm simulation CTDI values and calculated CTDI values with each other. In calculating patient`s chest effective doses. In both cases including children and adults we have used of quant index DLP, which is represented by device, in conversion index 0.017 the results of this study declare the linear relation between adult doses and children chest doses and this means that we are able to stimate children chest doses by having adult doses. the good approximation between children doses and adults can be considered as a sign of using appropriate protocol.
