Dose calculation of proton therapy based on Monte Carlo and empirical formula


 In this work, we used the Monte Carlo-based TOPAS simulation software to calculate the ambient dose equivalents and annual effective dose due to the secondary neutron field produced in proton therapy, also we introduced a USTC phantom to access the organ equivalent dose. The ambient dose equivalent and annual effective dose were calculated in several positions of interest inside and outside the facility. The simulation results were compared qualitatively to the results of the Empirical Formula, showing that the Empirical Formula calculations overestimated the dose, 28.95 times higher than the MC simulations, on average, which would lead to over shielding. In addition, the highest equivalent dose rate of a single radiation-sensitive organ simulated by TOPAS was 1.50 × 10−9 mSv/a for the eye lens, 2.36 × 10−3 mSv/a for limbs and 1.01 × 10−3 mSv/a for skin, which also meets the limits. Therefore, MC simulation has great advantages in shielding design and safety evaluation. And this work presents a new method to calculate the dose, introducing a more anthropogenic phantom can get more realistic results.