Virtual adaptation of physical phantoms to datasets derived from clinical tomographic examinations.

1.Description of purpose The simulations presented are part of an approach to the optimization of pediatric digital radiography. The method is used to allow for the choice of structures allowing for physical optimization of a system that is in its properties close to real patients. 2.Method(s) Virtual models created from tomographic datasets of humans are in use for calculation of dosimetric quantities of internal and external exposure. Monte Carlo Algorithms allow for the calculation of the radiation related properties of those phantoms as well as for the properties of simple physical structures. The data derived by those calculations is compared in order to adapt a physical model to different regions of diagnostic interest of the anthropomorphic model. 3.Results Making use of a pediatric voxel model of a child four weeks old thoracic radiography was simulated. This allows for a quantitative analysis of the image generation and the spatially resolved analysis of an x-ray examination. The results for different anatomical structures were compared to the output of the simulation of a step-like phantom made from Aluminum and PMMA. Statements about the x-ray related behavior of the step-structure can be directly experimentally validated. A low contrast plate was placed on each step which allowes to determine the energy dependence of the contrast noise ratio. 4.New or breakthrough work to be presented The work presented here shows how the use of voxelphantoms of high resolution can be extended past the calculation of dosimetric quantities. The application in projection radiography is the easiest approach to their application to clinical imaging. With the rise of computational power and improved resolution of the anthropomorphic phantoms the simulation imaging of higher resolution becomes possible. The correlation of those simulations to physical models helps to provide clear results of clinical relevance. 5.Conclusions We present a method for adaptation of physical studies to the data of real patients. This leads to the possibility to clarify the clinical relevance of clinical studies and allows for the design of studies adapted to different anatomical regions or diagnostic interest. 6.Submissions Elsewhere First steps of this work have been presented or accepted for presentation (oral in German) on the German society of Physics (DPG) March 2006 and the National Meeting of the German society of medical physics (DGMP) September 2006 in Nuremberg. The work is not and has not been submitted for publication or presentation elsewhere. Additional results produced by extended application of the methods presented are not yet submitted for publication or presentation anywhere