摘要： Unwanted exposure during irradiation in diagnostic procedures can be very harmful to health. Researchers have done extensive studies on heavy metals and their composites to prevent or reduce this risk. However, the disadvantages, such as high weight, rigidity or toxicity, limit the use of heavy metals. So far, great efforts have been devoted to designing and manufacturing lightweight /effective protective coatings that could attenuate or absorb radiation. In this regard, polymer composites are considered as potent materials. In the present study, the protective properties of polydimethylsiloxane hybrid nanocomposites containing single wall carbon nanotube (SWCNT) and cerium oxide nanoparticles (nanoceria) have been evaluated. The exposure tests on these coatings were performed by a diagnostic X-ray machine in the radiology department of the Urmia Imam Khomeini Hospital. To evaluate the amount of attenuation, beam intensity was measured at two narrow and broad beam geometries (NBG & BBG). The measurement procedures were well chosen according to the related Standards. The Field Emission Scanning Electron Microscope (FESEM) was applied in order to investigate the nanocomposite morphology and dispersion properties of nanoparticles. Thermal stability and chemical composition of the nanocomposites were studied by thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR), respectively. FTSEM images and elemental analysis proved that nanoparticle showed excellent dispersion into the polymeric matrix. The attenuation improved significantly compared to the polydimethylsiloxane pure coating. The rate of attenuation increases with increasing nanoceria percentage and ultimately the hybrid sample has a better efficiency than the sample with a similar percentage of the nanoceria.