- Activity is the transformation
(disintegration) rate of a radioactive substance
(Bq) - S.I. Unit
1 Bq = 1 disintegration per second (dps)
1 Ci = 3.7 x 1010 dps
1 Ci = 3.7 x 1010 Bq
dose is a physical quantity which represents the
energy imparted by radiation onto an absorbing material.
1 Gy = 1 joule per kilogram
1 Gy = 100 rads
Equivalent (DE) may be regarded as an
expression of dose in terms of its biological effect. DE takes account
of the fact that, for a given absorbed dose, such as 1 Gray, a radiation
of one type and/or energy may give rise to a greater biological effect
than a radiation of another type and/or energy.
Absorbed Dose x Quality Factor (Q)
depends on the type of radiation.
Q = 1 for gamma, x-ray and beta
Q = 10 for alpha
Q is used to compare the biological
damage producing potential of various types of radiation, given equal
absorbed doses. The effectiveness of radiation in producing damage
is related to the energy loss of the radiation per unit path length.
The term used to express this is linear energy transfer (LET). Generally,
the greater the LET in tissue, the more effective the radiation is in
- SIEVERT (Sv) - S.I. Unit
1 Sv = 100 rems
- Exposure is a quantity that expresses the ability of radiation to ionize air
and thereby create electric charges which can be collected and measured
1 R = 2.58 x 10-4 c/kg of air
Copied from: http://www.mcgill.ca/ehs/radiation/basics/units/