Chouin, N., Bernardeau, K., Davodeau, F., Chérel, M., Faivre-Chauvet, A., Bourgeois, M., Apostolidis, C., Morgenstern, A., Lisbona, A. and Bardiès, M. Evidence of Extranuclear Cell Sensitivity to Alpha-Particle Radiation Using a Microdosimetric Model. I. Presentation and Validation of a Microdosimetric Model. Radiat. Res. 171, 657–663 (2009).

A microdosimetric model that makes it possible to consider the numerous biological and physical parameters of cellular α-particle irradiation by radiolabeled mAbs was developed. It allows for the calculation of single-hit and multi-hit distributions of specific energy within a cell nucleus or a whole cell in any irradiation configuration. Cells are considered either to be isolated or to be packed in a monolayer or a spheroid. The method of calculating energy deposits is analytical and is based on the continuous-slowing-down approximation. A model of cell survival, calculated from the microdosimetric spectra and the microdosimetric radiosensitivity, z₀, was also developed. The algorithm of calculations was validated by comparison with two general Monte Carlo codes: MCNPX and Geant4. Microdosimetric spectra determined by these three codes showed good agreement for numerous geometrical configurations. The analytical method was far more efficient in terms of calculation time: A gain of more than 1000 was observed when using our model compared with Monte Carlo calculations. Good agreements were also observed with previously published results.