Which of the following is NOT considered to contribute to whole-body radiation dose?

To understand why extremities are considered not to contribute to the whole-body radiation dose, it's important to clarify what whole-body radiation dose refers to. The whole-body dose is typically calculated considering the radiation exposure to organs that are crucial for life-sustaining functions and those that are particularly sensitive to radiation.

Gonads and blood-forming organs, like the bone marrow, are critical components of the body that are directly linked to radiation's potential effects on health. The gonads are responsible for reproduction, and any radiation exposure to these organs can result in genetic mutations or reproductive issues. Blood-forming organs are vital for producing cells necessary for immune response and overall health, making their protection from radiation particularly important.

In contrast, while extremities (such as hands and feet) can certainly be exposed to radiation, they are not considered part of the “whole-body” dose in the same way as the core organs mentioned above. The concept of whole-body dose accounts for the overall risk and potential health impact arising from radiation exposure, emphasizing organs that are more at risk for cancer or other radiation-induced changes. Therefore, extremities do not contribute significantly to the assessment of whole-body radiation dose, leading to their exclusion in certain evaluations of radiation exposure.