Abstract
Protection quantities are important tools for the assessment of stochestic effects induced by radiations. Nowadays the concepts brought up by ICRP are well developed and are widely adopted in the laws, regulations and guidences. Since the protection quantities are defined in a human body, it is very difficult to measure those quantities directly. Therefore the only way to acquire the equivalent dose and the effective dose is through simulations. In this study, the equivalent dose and the effective dose were evaluated by a Monte Carlo code, MCNP, and by the numerical phantoms. Both a methematical phantom developed by Eckerman and a voxel phantom of ICRP Publication 110 were used in the calculation. Age-dependent protection quantities for external irradiations, the equivalent dose and effective dose results from the X-ray diagnosis and from the boron neutron capture therapy were evaluated and discussed in detail. The dependence between the age and the protection quantities shows that using only the dose conversion factors for adults may result in underestimations. For the X –ray radiological diagnosis, the peak tube voltage of the X-ray tube and the irradiation geometry severely affect the protection quanties evaluated. Especially for the radiological therapy, the treatment planning not only needs to focus on the dose in the tumor, but also take the exposure risk of the normal tissue into account. The parameters of the boron neutron capture therapy, such as source terms, irradiation geometries, phantoms, recommendations on radiation quantities, were all considered in the calculations. Their impact were also discussed.