Final answer:
Whole-body dose equivalents include radiation exposure to the gonads and lens of the eye because these areas are most sensitive to radiation and have greater significance in terms of potential health effects. Extremities are generally more resistant and do not contribute significantly to this measurement.
Step-by-step explanation:
The whole-body dose equivalent typically factors in the radiation exposure to tissues that are highly susceptible to radiation and contribute most significantly to the effects of radiation on the entire body. This usually includes key organs that, if damaged, could result in severe harm to a person's health or increased risk of stochastic effects like cancer. These organs and tissues receive a weighting factor that reflects their sensitivity to radiation.
Gonads are considered critical because of their sensitivity to radiation and their role in heredity. The lens of the eye is also included due to the risk of radiation-induced cataracts. However, while extremities like hands and feet can be exposed, they are generally more resistant to radiation and do not contribute as significantly to the whole-body dose equivalent as do the gonads and the lens of the eye.
The whole-body dose equivalents are designed to account for these differences and provide a method for comparing the overall risk of different types of radiation exposures that might not uniformly affect all parts of the body.