Gray 6 : The System International unit of absorbed dose of ionizing radiation. One gray (abbreviated 1 Gy) is 1 joule of absorbed energy per kilogram of matter
Federation of American Scientists, Glossary of Acronyms and Terms, Washington, DC,USA 2004. https://fas.org/pubs/_docs/10072004163905.pdf, (DPrep - Amer) {1003}