Radiation Protection in Mammography: Recommended Safety Procedures for the Use of Mammographic X-Ray Equipment - Safety Code 33

Appendix V

Radiation Measurement Units - International (SI) System

Irradiation

The unit of COULOMB/KILOGRAM (C/kg) has not found acceptance as the replacement of the ROENTGEN (R) as a unit of irradiation. Following the lead of the International Electrotechnical Commission, the AIR KERMA (in GRAYS) replaces the EXPOSURE (in ROENTGENS) as the measure of irradiation. The relationship between the two units is as follows:

1 Gy ~ 115 R
1 R ~ 8.73 mGy

1 mGy ~ 115 mR
1 mR ~ 8.73 μGy

Absorbed Dose

The GRAY (Gy) replaces the RAD (rad) as the unit of absorbed dose. The relationship between the two units is as follows:

1 Gy = 100 rad
1 rad = 10 mGy

1 mGy = 100 mrad
1 mrad = 10 μGy

Equivalent Dose

The SIEVERT (Sv) replaces the REM (rem) as the unit of equivalent dose. The relationship between the two units is as follows:

1 Sv = 100 rem
1 rem = 10 mSv

1 mSv = 100 mrem
1 mrem = 10 μSv

Note: m = milli = 10^-3; μ = micro = 10^-6