This measurement applies directly to the source and represents decay product per time unit.

Conventional unit: 1 curie = 37 billion disintegrations per second.

SI unit: 1 becquerel = 1 disintegration per second

conversions

1 curie (Ci) = 37 gigabecquerel (GBq)

1 gigabecquerel (GBq) = 27 millicurie (mCi)

Exposure is a quantity that expresses the radiation delivered to a point at a certain distance.

1 roentgen (R) = 258 microcoulomb/kg (µC/kg)

1 millicoulomb/kg mC/kg = 3876 milliroentgen (mR)

Under exposure a given material has an ability to absorb radiation. This differs with certain materials (think lead versus water) and some will absorb more or less as radiation passes through.

Conventional units: A dose of 1 rad means the absorption of 100 ergs of radiation energy per gram of absorbing material

SI units: A dose of 1 gray means the absorption of 1 joule of radiation energy per kilogram of absorbing material

conversion

1 Gy = 100 rad

1 rad = 0.01 Gy

The dose equivalent is a measure of biological effect for whole body irradiation. The dose equivalent is equal to the product of the absorbed dose and the Quality Factor.

The Quality Factor (Q) depends on the type of radiation:

X-ray, Gamma ray, or beta radiation: Q = 1

alpha particles: Q = 20

neutrons of unknown energy: Q = 10 (If the neutron energy is known, see more specific Q values at 10

conventional units: dose equivalent (rems) is the product of dose (rads) and Q

SI units: dose equivalent (sieverts) is the product of dose (grays) and Q

Conversion

1 Sievert (Sv) = 100 rem

1 rem = 0.01 Sievert (Sv)