A comparative study between pure bismuth/tungsten and the bismuth tungsten oxide for flexible shielding of gamma/X rays

Abstract

Thermoplastic vulcanizate based flexible W/Bi and bismuth tungsten oxide composites with different doping ratios from 20% to 100% are successfully fabricated. The ray attenuation abilities of the composites are determined at X-ray tube voltages of 80 KVp–120 KVp, and at gamma rays of 59 keV, 122 keV, 343 keV and 960 keV. The surface morphology and elements mapping of W/Bi and bismuth tungsten oxide particles within the polymer have confirmed a more uniform dispersion of bismuth tungsten oxide than W/Bi. Shielding parameters such as transmittance T, mass/linear attenuation coefficients μm and μ, as well as lead equivalent δPb are investigated experimentally and numerically by Monte Carlo code NECP-MCX as well as XCOM program. The transmittance of γ ray decreases exponentially with the areal density of the functional particles, and the best shielding of X-ray goes to 100 KVp tube voltage, followed by 80 KVp and 120 KVp. A comparison of the two series of composites are made that W/Bi always has advantages over bismuth tungsten oxide in attenuation coefficients and lead equivalent, because the extra containing oxygen atoms in bismuth tungsten oxide crystal actually provide very weak additional shielding. Test of mechanical property also reflects the advantage of using pure W/Bi over bismuth tungsten oxide in flexibility. As substitutes for Pb containing materials, these two types of composites could be of potential use in medical diagnosis, interventional surgery, or biological radiation protection, etc.