In general, the greater the dose, the greater the potential for biological effects.
b. Dose rate (how fast)
The faster the dose is delivered, the less time the body has to repair itself.
c. Type of radiation
For example, internally deposited alpha emitters are more damaging than beta
or gamma emitters for the same energy deposited.
d. Area of the body that receives a dose
In general, the larger the area of the body that receives a dose, the greater the
Extremities are less sensitive than blood forming and other critical organs. That
is why the annual dose limit for extremities is higher than for a whole body dose
that irradiates internal organs.
e. Cell sensitivity
The most sensitive cells are those that are rapidly dividing. Examples include
blood cells, hair follicles, and the cells lining the gastrointestinal tract.
Some individuals are more sensitive to environmental factors such as ionizing
The developing embryo/fetus is the most sensitive, and children are more
sensitive than adults.
In general, the human body becomes relatively less sensitive to ionizing
radiation with increasing age. The exception is that elderly people are more
sensitive than middle-aged adults due to the inability to repair damage as
quickly (less efficient cell repair mechanisms).
D. Prenatal Radiation Exposure
Although no effects were seen in Japanese children conceived after the atomic bomb, there
were effects seen in some children who were in the womb when exposed to the atomic
bomb radiation at Hiroshima and Nagasaki. Some of these children were born with a