AbstractID: 9705 Title: Dose Perturbation of a Novel Cobalt Chromium Coronary Stent on Intravascular
Brachytherapy 32P Catheter-based Source
Intravascular brachytherapy is adopted for the indication of in-stent restenosis based on results of clinical trials using mainly stainless
steel stent design. A new stent made of cobalt chromium L-605 alloy (CoCr, ρ = 9.22 g/cm3) (Multi-Link-VISION) has been
designed and recently introduced as an alternative for the 316L stainless steel stent (SS, ρ = 7.87 g/cm3) design (Multi-LinkPENTA). In this work, the Monte Carlo code MCNPX (v 2.4) is used to calculate the dose distribution for the 32P GALILEO
source in a stent model. The dose perturbation factor (DPF), defined as the ratio of the dose in water with and without the presence of
a stent, is used to compare results. Both stent designs are virtually expanded to 3.0 mm diameter using a finite element model. The
complicated strut shape for both the CoCr and SS stents are simplified using circular rings with an effective width to yield similar
metal-to-tissue ratio (MTR) of the actual stent design (12.5% and 17.5%, respectively). At 0.05 mm depth beyond the strut, the DPF is
0.64 (CoCr) and 0.71 (SS), and at 1mm tissue depth 0.91 (CoCr) and 0.93 (SS). Over the entire stented area, the average intima tissue
DPF is 0.95 (CoCr) and 0.92 (SS), and at 1mm tissue depth 0.96 (CoCr) and 0.93 (SS). We conclude that while the CoCr stent has a
higher Zeff and density than the SS stent, the DPF is comparable since its MTR and strut thickness was reduced relative to the SS stent
design.
Research is partially supported by Guidant Corporation