Abstract
High resolution voxel-based phantoms were used to assess organ doses from neutron external exposure. The segmented images of the Zubal voxel-based phantoms were obtained from the Imaging Science Research Laboratories at Yale University School of Medicine. The phantoms data were incorporated into MCNP4C2 and MCNPX Monte Carlo codes. There are twofold dose calculations in this study using monodirectional monoenergetic neutron beams in the energy range of 10 -9 (thermal) to 20 MeV, plus an extra calculation using a Maxwell fission spectrum source, under three different source irradiation configurations: anterior-posterior, posterior-anterior, and left lateral. Comparisons between the fractional dose contributions (in percent) from photon and neutron are taken into account in the determination of the total effective dose. The comparison with mathematical the MIRD phantom and the VIPMAN voxel phantom show partial agreement for neutron effective dose calculations and huge differences for organs absorbed doses. The differences between the three phantoms neutron exposure simulations are discussed and further limitations of voxel-based tomographic phantom are investigated. The future work at the end of this thesis presents a voxel-based eye phantom for high energy proton therapy with initial simulation of a proton beam.