Low-energy 103Pd gamma (X-ray) source for vascular brachytherapy.

PURPOSE: This article describes the merits of 103Pd, a low energy x-ray emitter, as a new and potentially superior candidate for intraluminal brachytherapy. 103Pd can be ion implanted into different materials, designs, and devices for vascular brachytherapy. METHODS: The mass-analyzed ion implantation process has been used to embed the desired activity of 103Pd into the surface of 316L stainless steel stents. The low-energy, 21-keV x-ray from 103Pd delivers reasonably homogeneous radiation to the vessel wall and loses intensity rapidly beyond the immediate vicinity of the source. Shielding for 103Pd x-rays is trivial and the issues regarding safety, health hazards, storage, and handling are easily manageable. RESULTS: Experimental data on 103Pd ion-implanted stents show a clean gamma-ray spectrum devoid of any radioimpurity. Activity measurements within a batch demonstrate little stent-to-stent variation (approximately 2%), excellent axial and radial uniformity (<10%), and minimal dissolution in a saline environment (approximately 0.02%). The dosimetry shows the focused radiation field for 103Pd stents and rapid fall-off beyond a few millimeters of the stent. Furthermore, the 103Pd dosimetry indicates that a 350 muCi stent will deliver approximately 14 Gy at 1-mm distance, over its lifetime. CONCLUSION: 103Pd is an appropriate source for vascular brachytherapy. It has an appropriate combination of half-life (16.93 days) and energy (21 keV). The half-life of 103Pd delivers the dose with an acceptable dose rate for stent applications while, at the same time, allowing for manageable shipping, storage, and/or disposal.

Silver modification of polyethylene terephthalate textiles for antimicrobial protection.

The safety and in vitro effectiveness of applying silver to polyethylene terephthalate fabric mechanical heart valve (MHV) sewing cuffs for the prevention of prosthetic valve endocarditis (PVE) were evaluated. PVE is an infrequent but grave complication of cardiac surgery associated with mortality rates potentially exceeding 50%. A poor response to antibiotic therapy is partly responsible for the high mortality rates. Silver is a well known antimicrobial agent with broad effectiveness. Preliminary in vitro microbial challenge studies of the coated fabric using the New York State 63 bacteriostatic test and Dow Corning Shake Flask test showed a > or = 97% reduction for most organisms tested. Sheep mitral valve replacement studies suggest comparable tissue ingrowth of uncoated and coated fabric with a more organized, thinner pannus formed on silver coated fabric. Low levels of silver were present in the serum at all time periods. These results indicate MHVs with silver coated cuffs may provide additional protection against PVE.