Ionising radiation is the name given to every particle radiation or electromagnetic radiation that can remove electrons from atoms or molecules, resulting in a residue of positively charged ions or molecule particles (ionisation). In direct ionising radiation, the energy transfer takes place by the Coulomb interaction, i.e. the invading primary charged electrons, protons, etc. give their energy to the electrons of the absorber medium. Indirectly ionising radiation, however, is produced by electrically neutral particles like photons and neutrons and the energy release is a two-step process: first charged particles (electrons, protons, etc.) are released from the atoms of the absorbing medium and then these charged secondary particles – similar to the direct ionising radiation – pass their energy to the electrons of the absorber medium.