Effective Dose

 

 

The concept of effective dose takes into account the risk to the person exposed to radiation that is not uniform over the entire body.

 

          Different organs have different sensitivities to radiation:

 

          This is expressed by the tissue weighting factor:  wT

 

Tissue Weighting Factors:

Gonads 0.20
Bone Marrow; Colon; Lung; Stomach; 0.12
Bladder; Breast; Liver; Esophagus; Thyroid; Remainder; 0.05
Bone Surface; Skin; 0.01

To get effective dose:

 

For each tissue or organ:  multiply the equivalent dose it received by its tissue weighting factor, then add up the results for all the tissues and organs.

 

Effective Dose is expressed in units of ``rem'' or ``sievert.''

 

Thus, for radiation protection purposes, people usually use the units "rem" or "sievert"

 

 

As an example, if 1 rem is received only by the lungs, this results in an effective dose to that person of 0.12 rem.  This means that 1 rem received by the lungs poses approximately the same risk as 0.12 rem to the entire body.

 

If you receive a non-uniform radiation exposure to your body of 1 Sv effective dose you could expect approximately the same amount of harm from the radiation as if you had received 1Sv uniformly over the entire body.