United States Nuclear Regulatory Commission - Protecting People and the Environment

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?


(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)

Page Last Reviewed/Updated Tuesday, September 01, 2015