Abstract
Neutrons for BNCT using the near threshold 7Li(p,n)7 7Be reaction have typical energies ranging from a few KeVs to about a 100KeV.
An effective thermal neutron distribution in the living body can be achieved by introducing BDE (Boron dose enhancer) in the irradiation field (i.e., at the surface of the body).
It was previously shown that the dose distribution in the living body can be modified according to the requirements of the treatment condition by varying the BDE thickness and/or material type.
In this study, we verified the effect of changing the BDE diameter on the dose distribution both along the central axis and off-axis directions for a 4.63cm beryllium BDE.
Simulation calculations for the neutron and gamma ray production in the lithium target were carried out by means of Lee's method. While particle transport was performed using the MCNP4C2 code.
The treatable protocol depth (TPD) which is the central axis depth that satisfies the prescribed tumor dose and the tolerance dose from heavy charged particles (PD(hcp)) and the tolerance dose from gamma rays (PD(γ)) for normal tissue was used to evaluate the dose distributions in a water phantom obtained for each BDE diameter.
