ABSTRACT
The absorbed dose of radiation is de‚ned as the energy absorbed per unit mass of irradiated material. The stopping power means the energy lost by charged particles in the material. This quantity is not necessarily equal to the absorbed energy by the target. Above all, a problem occurs for the target smaller than the range of secondary electrons. Such a microscopic concept in dosimetry, called microdosimetry, plays an important role to understand the radiation effect on cells (∼µm range) or DNA (at ∼nm range).
