Parametric Stochastic Model of Bone Structures to Be Used in Computational Dosimetric Phantoms of Human Skeleton

The estimation of dose factors for active marrow exposed to bone-seeking beta-emitters, such as 89 Sr and 90 Sr/ 90 Y (0 -1.5 respectively), is an important task of bone dosimetry. Monte Carlo simulations of electron -photon transport to calculate the active marrow doses are based on the geometrical modeling of bone structures. The model geometry should consist of accurate descriptions of spongiosa fine structure and cortical bone thickness (because of the high probability of low energy electron emission) as well as descriptions of bone macrodimensions (because the maximum electron path length in spongiosa is about 5-9 mm). New computer tomography (CT) -based methods are widely applied to develop computational dosimetric phantoms. The advantage of the CT-based method is in high realism of the description of complex bone shape as well as in the possibility of an adequate description of bone microstructure with CT. However, the method has a number of disadvantages, viz.: