Microdosimetry model for boron neutron capture therapy: I. Determination of microscopic quantities of heavy particles on a cellular scale

Due to the limitations of existing microdosimetry models, a new model calle d MICOR has been developed to analyze the spatial distribution of microscop ic energy deposition for boron neutron capture therapy (BNCT), As in most e xisting models, the reactions independent of the incident neutron energy su ch as the boron and the nitrogen capture reactions can be considered. While other models do not include reactions that are dependent on the neutron en ergy such as the proton recoil reaction, the present model is designed so t hat the energy deposition resulting from these reactions is included. The m odel MICOR has been extended to enable the determination of the biological effects of BNCT, which cannot be done with the existing models. The present paper describes the determination of several microscopic quantities such a s the number of hits, the energy deposition in the cell nucleus, and the di stribution of lineal and specific energy deposition. The companion paper (R adiat. Res. 155, 000-000 2001) deals with the conversion of these microscop ic quantities into biological effects. The model is used to analyze the res ults of a radiobiological experiment performed at the HB11 facility in the HFR in Petten. This analysis shows the value of the model in determining th e dose depositions on a cellular scale and the importance of the extension to the energy deposition of the proton recoil. (C) 2001 by Radiation Resear ch Society.