Personnel exposure from positron emitters

Positron emitters may contribute considerably to the radiation from induced radioactivity in accelerator environments. In most cases of thick radiating objects (magnets, shielding walls) the dose rate from gamma emitters, including the 511 keV annihilation photons from positron emitters, dominates the radiation field. Direct positron interaction in skin tissue and in the lens of the eye may be an important contribution to absorbed dose in cases of thin targets and beam separating septa. Results of calculations and measurements show, however, that the dose to the lens of the eye is limited by limitations placed on whole-body doses. Irradiation from positron emitters gives rise to about the same absorbed doses as those experienced in the case of an electron exposure. (author)