title: Absorbed dose estimates to structures of the brain and head using a high-resolution voxel-based head phantom.
abstract: The purpose of this article is to demonstrate the viability of using a high-resolution 3-D head phantom in Monte Carlo N-Particle (MCNP) for boron neutron capture therapy (BNCT) structure dosimetry. This work describes a high-resolution voxel-based model of a human head and its use for calculating absorbed doses to the structures of the brain. The Zubal head phantom is a 3-D model of a human head that can be displayed and manipulated on a computer. Several changes were made to the original head phantom which now contains over 29 critical structures of the brain and head. The modified phantom is a 85 x 109 x 120 lattice of voxels, where each voxel is 2.2 x 2.2 x 1.4 mm3. This model was translated into MCNP lattice format. As a proof of principle study, two MCNP absorbed dose calculations were made (left and right lateral irradiations) using a uniformly distributed neutron disk source with an 1/E energy spectrum. Additionally, the results of these two calculations were combined to estimate the absorbed doses from a bilateral irradiation. Radiobiologically equivalent (RBE) doses were calculated for all structures and were normalized to 12.8 Gy-Eq. For a left lateral irradiation, the left motor cortex receives the limiting RBE dose. For a bilateral irradiation, the insula cortices receive the limiting dose. Among the nonencephalic structures, the parotid glands receive RBE doses that were within 15% of the limiting dose.
authors.affiliation: Department of Mechanical Engineering, The Ohio State University, Columbus 43210, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Evans
authors.forename: T E
authors.initials: TE
authors.lastname: Blue
authors.forename: N
authors.initials: N
authors.lastname: Gupta
mesh_terms: D016754:Boron Neutron Capture Therapy / Q000379:methods*; D001921:Brain / Q000000981:diagnostic imaging* / Q000528:radiation effects*; D006257:Head / Q000502:physiology; D006801:Humans; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011859:Radiography; D011874:Radiometry / Q000379:methods*; D012984:Software; D014018:Tissue Distribution