Health Physics Questions and Answers - Question 176

Question 176: 10 CFR 20.1201 (a) (2) (ii) states a limit of "A shallow-dose equivalent of 50 rem (0.50 Sv) to the skin or to any extremity."

(a) Can a person receive 50 rem shallow dose equivalent to the skin of the lower arm (extremity) and 50 rem shallow dose equivalent to the upper arm non-extremity), without having an overexposure?

(b) Can a person receive 50 rem shallow dose equivalent to the left upper arm, then the same dose to the right upper arm, without having an overexposure?

(c) Can a person receive 50 rem shallow dose equivalent to each extremity during one year?

Answer:

(a) Yes, as long as the total shallow dose equivalent does not exceed 50 rem in either position. The skin of the extremity is not considered in the shallow-dose equivalent limit to the skin of the whole body. The annual limits are a shallow-dose equivalent of 50 rem (0.50 Sv) to the skin or to any extremity.

(b) Again, as long as it can be shown that the total shallow dose equivalent does not exceed 50 rem at any one location on the skin of the whole body, there is no violation. If the two different areas of the skin of the whole body each receives 50 rem total shallow dose equivalent during the year, then the limit has not been exceeded.

(c) Yes. The regulation states ". . . or to any extremity;" therefore, a worker may receive a shallow-dose equivalent of 50 rem to each of the four extremities.

(Reference: 10 CFR 20.1201, 10 CFR 20.1003, Regulatory Guide 8.34)