Thoracic radiography was simulated making use of a virtual pediatric model created from tomographic data (voxelphantom) of a child eight weeks old. The dataset was scaled down to fit the dimensions of a premature newborn. The simulation allows a quantitative and spatially resolved analysis of the x-ray image generation. The transmission behavior of different anatomical regions present in the voxelphantom was compared to the output of the simulation of a step-like phantom made from aluminum and PMMA. The step like structure of the simulated model can be easily built and statements about its x-ray related behavior can be directly validated by means of experiments. A thin contrast plate was placed on each step to make the determination of dependences e.g. between the applied radiation energy and the contrast to noise ratio possible.