A Conceptual Design Optimization of Collimator With 181Ta as Neutron Source for Boron Neutron Capture Therapy Based Cyclotron Using Computer Simulation Program Monte Carlo N Particle Extended

The optimization of collimator with 30 MeV cyclotron as neutron source and ¹⁸¹Ta as its proton target. cyclotron assumed work at 30 MeV power with 1 mA and 30 kW operation condition. Criteria of design based on IAEA’s recommendation. Using MCNPX as simulator, the result indicated that with using ¹⁸¹Ta as target material with 0.55 cm thickness and 19 cm diameter, 25 cm and 45 cm PbF₂ as reflector and back reflector, 30 cm ³²S as a moderator, 20 cm ⁶⁰Ni as fast neutron filter, 2 cm ²⁰⁹Bi as gamma filter, 1 cm ⁶Li₂CO_3- polyethylenes as thermal neutron filter, and 23 cm diameter of aperture, an epithermal neutron beam with intensity 4.37 x 10⁹ n.cm^-2.s^-1, fast neutron and gamma doses per epithermal neutron of 1.86 x 10^-16Gy.cm².n^-1and 1.93 x 10^-13Gy.cm².n^-1, minimum thermal neutron per epithermal neutron ratio of 0.003, and maximum directionality 0,728, respectively could be produced. The results have passed all the IAEA’s criteria.