Quantitative planning of neutron capture therapy according to the kinetics data of Gd (III) complexes with magnetic resonance imaging

Neutron capture therapy (NCT) with thermal neutron beams of high flux density is the most promising method of therapy for inoperable malignant brain tumors using Gd in stable acetate complexes with possibility of visualization by magnetic resonance imaging (MRI). The effectiveness of NCT is determined by the maximum dose that is created in tumor cells by products of the capture of thermal neutrons by Gd atoms. Analyzing the kinetics of direct absorption and inverse diffusion of Gd complexes in brain tumor tissue by MRI, we were able to show that it is linear in all cases and Gd concentration in the tumor at the moment T is defined as Сtum(Т) = kpl-tum ∙ ∫ Сpl(t)∙exp(-ktum-pl (T-t))dt. At the same time, the value of the direct transport factor kplasma-tumor=5.87±0.31 is an order of magnitude higher than the rate of reverse diffusion ktumor-plasma=0.91±0.23. Then, according to the data of a single diagnostic dynamic study, it is possible to calculate the optimal regimen of Gd administration to achieve the therapeutic effect of a neutron beam of known flux density for NCT, while avoiding the release of Gd in healthy tissues.