The new special names of SI units in the field of ionizing radiations.

New SI units for ionizing radiations have been recommended by the internation Commission on Radiation Units and Measurements (ICRU). These are the becquerel (symbol Bq), equal to the second to the power -1, and the gray (symbol Gy), equal to the joule per kilogram. It was recommended that the roentgen be replaced as the unit of exposure by the coulomb per kilogram (C/kg), for which no new name was proposed. The ICRU recommends that the units rad, roentgen, and curie be gradually abandoned over a period of ten years and that preparatory steps to this end be taken as soon as possible by various national and international bodies in order to facilitate a smooth, safe, and efficient transition.