U.S. Nuclear Regulatory Commission
Question 177: (a) If a worker is exposed to an external
source such that his head is the maximally exposed area of
the body, are the doses to the head limiting, since the
head is not included under the definition of "extremity?"
(b) What is the annual dose limit to the head, assuming no
other internal or external dose?
Answer: (a) Yes. The annual limit for the dose to the
head is the same as the annual limit to the trunk and other
portions of the whole body, which in the absence of
internal dose, is equivalent to 5 rem deep dose equivalent.
b) The limit is 5 rem TEDE. (Reference: 10 CFR 20.1201)