One of the important issues in the simulation work is proper representation of the simulated objects. The geometrical shapes of the simulated objects may range from very simple to very complicated geometries. In addition, a lot of objects come with heterogeneous material properties that need to be included into simulations. These two issues play important roles in both industrial and medical radiography simulations. CT (computed tomography) became widely available to the radiography community in the recent years. Since this technology provides two‐dimensional images, CT images can be used to build models toward using in simulation work. In this work, we developed a CT image based algorithm to account for object shape complexities and heterogeneities. The resulting algorithm and absorbed energy doses in a human body part and ideal detector images obtained through the algorithm will be presented. © 2003 American Institute of Physics