Characterization of the Radiation Contamination in an 18MV Linac Treatment Room Made of some Nanoparticles Mixture

Propose: 

shielding medical radiation requires deep knowledge of radiation physics and shielding design methods.

Effective neutron mass removal cross-section (ΣR/ρ) was derived for the ordinary concrete doped with 50nm of TiO2 (5%), Sm2O3 (5%), WO3(5%), B4H (5%), SiO2 (5%) nanoparticles mixture with MCNP5 estimation and N-XCOM calculation was conducted. The ordinary concrete (with a density of 2.35 g/cm3) composition elements ΣR/ρ were also estimated. An 18MV Variuan 2100Clinac room made of obtained nano-concrete and with three legs included maze simulated and secondary neutron and capture γ-ray dose equivalent (DE) were estimated. required shielding Lead and Borated-Polyethylene (BPE) were calculated according to the estimated doses and guidelines a negligible shielding, close to an Open-Door maze was obtained.

Total ΣR/ρ of the neutron with energies 100 keV-2000keV was estimated as 0.02802-0.02687 cm2/g using the MC simulation method in good geometry while N-XCOM software calculated the same values as 0.02810- 0.02687 cm2/g. ΣR/ρ was also derived using MC and N-XCOM for the elements in the pure ordinary concrete. MCNP5/1.60 MC simulation code was calculated secondary neutron and capture γ-ray dose equivalent as 1.65×10-07 mSv/isocenter Gy and 7.98×10-06 mSv/isocenter Gy.

It was concluded that the nanoparticles mixture present in the ordinary concrete enhanced the shielding properties of the concrete and additional bendings in the maze besides the effect of the nanoparticles, designed a room with negligible shielding at the maze entrance that was close to the Open-Door 18MV room.