Different forms of radiation with identical absorbed doses may differ in their effect on living things. Neutrons and alpha particles are harder on human tissues than are beta particles or gamma rays. To account for this variation, the absorbed dose is multiplied by a radiation weighting factor that varies according to the type of radiation. The product is called the equivalent dose . Different tissues or organs receiving identical equivalent doses may differ in their response to radiation damage.
Skin is durable stuff that is designed to take abuse and be discarded as it wears out.
Bone marrow is much less durable and its loss affects the body as a whole since red blood cells are produced within it. To account for this variation, the equivalent dose is multiplied by a tissue weighting factor that varies according to the organ or tissue exposed. The product is called the effective dose . It relates the absorbed dose to the equivalent biological damage of the radiation in a human. It relates the equivalent dose to the effective biological damage of the radiation in a human.