CALCULATION BY MICRODOSIMETRIC METHODS OF THE FORMATION BY A SINGLE HIGH-ENERGY PHOTON OR ELECTRON OF 2 LESIONS IN THE SAME DNA MOLECULE

The formation by a single high-energy photon or electron of two lesion s (such as double-strand breaks) in the same DNA molecule is calculate d by microdosimetric methods. The result is similar to a previous calc ulation using a target theory approach. Thus, it is reasonably certain that, for greater than or equal to 1 Gy of sparsely ionizing radiatio n acting on a DNA molecule of greater than or equal to 10(6) base pair s, less than or equal to 3% of two-hit events such as deletions are fr om a single radiation event.