Comparison Study of Beryllium and Lithium Target System for Beam Shaping Assembly Used in Boron Neutron Capture Therapy

Abstract

Boron neutron capture therapy (BNCT) is a selective targeting cancer therapy method which is by radiating epithermal neutron beams to a tumor which has been injected by boron-10 compound. The implementation of this method requires 2 (two) key elements, namely the boron-10 compound and the irradiating neutron beam of epithermal energy level. The neutron source used in this research was 13 MeV 1mA cyclotrons which have been developed by Indonesia National Nuclear Energy Agency. This paper was preoccupied in beam shaping assembly (BSA) target system. BSA target system is used to convert the proton produced by cyclotron into neutron. IAEA generated a recommendation for BNCT neutron beam quality, one of them was epithermal neutron flux which is higher than 109 𝑛𝑛/𝑐𝑐𝑐𝑐2. To fulfill this requirement it is definitely crucial that the neutron flux in the target system produces the possible highest neutron flux before moderation. In this paper, simulation was conducted to find the best target system and thickness for cyclotron 13 MeV that can produce the highest neutron flux before moderation using MCNPX. From the simulation, beryllium was evidenced to yield higher neutron flux compared to lithium. Beryllium neutron flux peaked at 1250 μm with neutron flux of 4.87E+12 𝑛𝑛/𝑐𝑐𝑐𝑐2 and lithium neutron flux peaked at 4000 μm with flux of 3.53E+12 𝑛𝑛/𝑐𝑐𝑐𝑐2.