Water-equivalence of ZrO2 doped polystyrene by Monte Carlo simulation

Abstract

Objective To design water-equivalent plastic scintillator detector for the measurement of absorbed dose in tumor radiotherapy. Methods The concentration of ZrO2 to be doped in polystyrene was estimated according to the empirical formula, and then the Monte Carlo program Geant4 (GEometry And Tracking 4) was used to simulate the energy deposition and transport process of X-rays with different energies in water, solid water RW34 (composed of 2.1 wt% TiO2 doping polystyrene) and different concentrations of ZrO2 particles doped in polystyrene. The dose and attenuation coefficients were compared among different materials at different depths of water. Results The doses at different depths and the attenuation coefficient of polystyrene (doped with about 0.4 wt% ZrO2 nanoparticles) were much more consistent with those of water and even exhibit much better water-equivalence than RW34. Conclusions The simulation results provide the basis for the development of water-equivalent scintillator. Key words: Geant4; Water-equivalent; ZrO2nanoparticle; Polystyrene