Safety Code 35: Safety Procedures for the Installation, Use and Control of X-ray Equipment in Large Medical Radiological Facilities

Appendix VIII: Radiation Measurement Units

Exposure

Following the lead of the International Electrotechnical Commission, the air kerma (in gray, Gy) replaces the exposure (in roentgen, R) as the measure of exposure. The relationship between the two units is as follows:

• 1 Gy ~ 115 R
• 1 mGy ~ 115 mR
• 1 R ~ 8.73 mGy
• 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 mGy ~ 100 mrad
• 1 rad ~ 10 mGy
• 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 mSv ~ 100 mrem
• 1 rem ~ 10 mSv
• 1 mrem ~ 10 µSv