Improvement of thermal neutron fluence for BNCT treatment of deep-seated turmors: Simulation calculation and phantom experiments

It is important to get sufficient thermal neutron flux at the tumor for the purpose of increasing the efficiency of NCT. To improve the effect of the treatment for a tumor deeply seated in a human body, the distribution of thermal neutron fluence should be improved. In this paper, the authors studied on the methods for increasing the thermal neutron doses at the deep location from the viewpoint of the physics and engineering. The following three methods are taken into consideration: (1) the adjustment of the directional components of the thermal neutron beam, (2) the making of a void in a human body and (3) the partial replacement of body water (i.e. light water) with heavy water in a human body. Phantom experiments and simulation calculations were performed in order to confirm the effects of these methods and to study their characteristics