The concepts of ionizing radiation and energy imparted defined by the ICRU [International Commission on Radiation Units] in 1971 were critically analyzed. The definitions become more consistent by changing them at 2 points. Charged particles with insufficient kinetic energy to ionize by collision but which are capable of initiating nuclear and elementary particle transformations are suggested to be classified as ionizing particles. In addition, the expressions the energy released or the energy expended in a nuclear or elementary particle transformation are suggested to be specified as the change in rest-mass energy of nuclei and elementary particles. Then the ionization casued by, for instance, nuclear reactions contributes to the energy imparted and the Q-value of an excitation or deexcitation of the electron structure, regarded as an elementary particle transformation, is zero.