A dose-point-kernel model for a low energy gamma-emitting stent in a heterogeneous medium

A computer dose model for a low energy gamma-emitting stent in a heterogene ous medium is described. The method is based on the Sievert model which is adapted to the dose-point-kernel (DPK) model to compute the dose distributi on about filtered gamma sources (Sievert-DPK model). The new gamma stent mo del can take into account effects such as the metallic wire attenuation and the presence of dense calcified plaque in a stented artery. The Sievert-DP K model is tested against numerical simulations around cylindrical shell so urces with dimensions comparable to those of a stent using a Monte Carlo tr ansport code. For low energy gamma sources (Cs-131 and Pd-103), it is shown that the Sievert-DPK model is consistent with the Monte Carlo results to a bout 5%-10% for distances up to 5 mm from the cylindrical surface and 2.5 m m beyond the cylinder edges. These results indicate that the Sievert-DPK mo del may be useful to predict the dose in intravascular therapy applications for heterogeneous systems consisting of soft tissue, metal and dense plaqu e. (C) 2001 American Association of Physicists in Medicine.