Lead is commonly used in medical radiology departments as a shielding material. Lead-based protective materials are also used by clinical personnel during X-ray image-guided interventional radiology (IVR) procedures. However, lead is extremely toxic and prolonged exposure to it can result in serious health concerns. Polymer composites, on the other hand, can be designed to be lead-free in addition to being lightweight, conformable, cost effective, and potentially capable of significantly attenuating X-rays. Nanomaterials have unique material properties that can be exploited to develop novel lead-free radiation-protection materials. In this study, polydimethylsiloxane (PDMS) nanocomposites were fabricated using different weight percentages (wt %) of bismuth oxide (BO) nanopowder. The attenuation properties of the nanocomposites were characterized using diagnostic X-ray energies from 40 to 150 kV tube potential and were compared to the attenuation characteristics of 0.25-mm-thick pure lead sheet. The PDMS/BO nanocomposite (44.44 wt% of BO and 3.73-mm thick) was capable of attenuating all the scattered X-rays generated at a tube potential of 60 kV, which is the beam energy commonly employed in IVR. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013