Neutron/photon physics investigation of brain tumor treatments with BNCT
Abstract
As basis for a preclinical neutron beam evaluation for BNCT of brain tumors, a computational method is developed to calculate the tumor-cell survival probability vs. treatment conditions. Here, a treatment condition is characterized by the spectrum and lateral size of neutron beams, single or bilateral exposure, and the choice of boron drugs. The radiation transport from the neutron source to tumors is carried out by the Monte Carlo method: (1) reactor-based BNCT facility modeling to yield the neutron spectra at an irradiation port; (2) dosimetry to limit the neutron fluence below a tolerance dose; (3) calculation of the $\sp{10}$B(n,$\alpha)\sp7$Li density in tumors using neutron beams grouped by energy and angle. Finally, from a cell-killing chance by the (n,$\alpha$) reaction the tumor-cell survival probability is calculated for various treatment conditions. The 10 cm beam penetrates deeper and delivers a higher thermal neutron flux at depth than the 4 cm beam. A near surface tumor could be effectively treated by single exposure with the maximum survival probability of 10$\sp{-2}$-10$\sp{-4}$ at the most likely range of the cell-killing chance per (n,$\alpha$) reaction, while a deep tumor should rely upon bilateral exposure to avoid a high cell survival at depth. By reducing either the low or the fast energy wing of the spectrum, the tumor-cell survival can be somewhat decreased, compared to the original spectrum. However, with the both energy wings reduced, the survival probability can be furthermore decreased by factors of 2-10, depending on the treatment conditions.
Degree
Ph.D.
Advisors
Ott, Purdue University.
Subject Area
Nuclear physics|Radiation|Radiology
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