Feasibility study on the use of 230MeV proton cyclotron in proton therapy centers as a spallation neutron source for BNCT.

Abstract

The feasibility of using 230MeV proton cyclotrons in proton therapy centers as a spallation neutron source for Boron Neutron Capture Therapy (BNCT) was investigated. BNCT is based on the neutron irradiation of a 10B-containing compound located selectively in tumor cells. Among various types of neutron generators, the spallation neutron source is a unique way to generate high-energy and high-flux neutrons. Neutron beam was generated by a proton accelerator via spallation reactions and then the produced neutron beam was shaped to be appropriate for BNCT. The proposed Beam Shaping Assembly (BSA) consists of different moderators, a reflector, a collimator, as well as thermal and gamma filters. In addition, the simulated Snyder head phantom was utilized to evaluate the dose distribution in tumor and normal tissue due to the irradiation by the designed beam. MCNPX2.6 Monte Carlo code was used to optimize BSA as well as evaluate dose evaluation. A BSA was designed. With the BSA configuration and a beam current of 104nA, epithermal neutron flux of 3.94×106 [n/cm2] can be achieved, which is very low. Provided that we use the beam current of 5.75μA, epithermal neutron flux of 2.18×108 [n/cm2] can be obtained and the maximum dose of 38.2 Gy-eq can be delivered to tumor tissue at 1.4cm from the phantom surface. Results for 230MeV protons show that with proposed BSA, proton beam current about 5.75μA is required for this purpose.