The SI unit of a dose equivalent of radiation is:

Radiation absorbed dose, Dose equivalent, and exposure are often measured and stated in the older units called rad, rem, or roentgen respectively. International System of Units (SI) for radiation measurement is now the official system of measurement and uses the "gray" (Gy), "sieve" (Sv), Coulomb/Kg for absorbed dose, equivalent dose and exposure respectively. Conversions are as follows: 1 Gy = 100 rad 1 Sv = 100 rem 1 coulomb/ Kg= 3876 Roentgen Ref: Park's textbook of Preventive and Social Medicine, 21st edition, page-687