a. The rad is a unit of absorbed dose and it describes energy absorbed per gram of absorbing material.

1 rad = 100 ergs absorbed per gram of any substance or 0.01 joules per kilogram

b. When water or soft tissue absorbs x or gamma radiation (100 KeV to 3 MeV), the absorbed dose per roentgen is between 0.93 and 0.98 rad. Therefore, rads and roentgens are approximately the same for x or gamma rays in those energies.

c. The rad is used for x and gamma rays and the particulate radiations, alpha and beta particles, and neutrons.

d. Recently, the 15th General Conference of Weights and Measures adopted some new names and units. The Gray (symbol Gy) has been adopted as the special unit of absorbed dose.

1 rad = 0.01 joule/kilogram or 1 Gy = 100 rads

X-ray Schools | X-ray and Radiation Safety
For Informational Purposes Only - Based On US Army Radiation Safety Training