عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Intravascular brachytherapy is simulated with Palmaz-Schatz stent, manufactured by Cordis Co. that is radioactived with 188Re source, using the MCNPX code. Functions and dosimetric parameters, were calculated in cylindrical coordinates and results compared with the latest standards and AAPM TG-60 group offers, published experimental data and also other performed simulations with various programs for various locations around the source and some sensitive tissues of the body.
The probabilistic risks were estimated for heart treatment and sensitive tissues around the treated vessel based on the results of this simulation and the latest reports of ICRP standards. For stent 188Re with initial activity of 1 mCi initial absorbed dose rate in plaque is equal to 9.35´10-6 Gy/s, maximum of absorbed dose in plaque after 28 days, is almost 83 cGy and maximum of effective equivalent dose rate in plaque, with the weight factors, reported by ICRP60, approximately equal to 4.5´10-7 Sv/s was obtained. Therefore, for accessing to the suitable dose of brachytherapy, the primary activity of radioactive stents should be considered about 24-30 mCi. Hence, the achievement dose of gamma ray of 188Re will be 0.27-0.32 Gy that this amount is much less than threshold of dose of gamma risk. This feature permits using 188Re source for therapeutic use because of beta particles emitted from them. In addition, because of having gamma ray, it is simultaneously used for diagnostic use and as gamma camera.