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Evaluation of Silver Dressing as Bolus

E Hipp

E Hipp*, S Becker, K Osterman, NYU Medical Center, New York, NY

SU-E-T-256 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: Anti-microbial silver wound dressing may be useful as a bolus material. This study measures the water-equivalent-thickness of a silver wound dressing to characterize it for clinical use. This nylon-mesh dressing, with its permanently plated silver surface (546 mg Ag/100 cm²) may meet the need for bolus with fine variability of thickness and self-sterilization.

Methods: A percent depth dose (PDD) curve was measured in plastic water (CNMC Best Medical) using a parallel plate chamber (PTW N34001) for an 8 x 8 cm field size, 6 MV beam, 100 cm SSD with a linear accelerator. Measurements were repeated under varying thicknesses (0.5 mm, 1mm, and 2 mm) of silver dressing material, 10 cm x 11 cm (Silverlonâ„¢ Antimicrobial silver wound contact dressing WCD-466). Control measurements were also made in a small water tank.

Results: For every layer of dressing added (~0.5mm) the PDD shifts to the left along the depth axis. A 2 mm offset applied to the position values of the 2 mm (4-layers) PDD curve causes superposition with the control PDD. This suggests that 2 mm of silver dressing performs similarly to 2 mm of plastic water. This was verified with measurements under clinical setup conditions, 100 cm to the top of the parallel plate chamber, ie. to skin, with bolus placed on top, under 2 mm plastic water (73.40%) and under 2 mm silver dressing (73.41%). Measurements in a water tank for this equivalent depth agree within 1%.

Conclusion: The bolus properties of silver-mesh dressing appear to be water-equivalent. Silver dressings can be used as bolus and may be particularly beneficial when fine variations are desired or when maintaining an anti-microbial environment is of particular value.

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