Analysis of scattering gamma rays of 60Co for different shielding materials and phantom materials using MCNP Monte Carlo code

Gamma ray is one of radiations used for radiation therapy. In the biological study sometimes we need low-dose irradiation. In such a case, dose rate is sometimes decreased by using shielding materials. For such purpose we need to reduce scattering gamma rays by selecting suitable materials, which reduce quality change of irradiating gamma rays. On the other hand, Monte Carlo calculation is a technique to follow each scattering process of the particles. Therefore, it is possible to calculate spectrum, of which measurement is usually difficult. In this paper we use water, aluminum, iron, tungsten and lead as shielding materials. According to the calculation it is found that the most suitable material is lead and that its contribution of scattering in kerma is 37%. On the other hand, the highest material is water (50%). Difference of the contribution of scattering among different phantom materials are calculated for tissue, muscle, bone, A150, acrylic, nylon and water. The results indicate that the highest material is bone (35%) and that other materials such as tissue (31%) are similar. (author)