Nonstochastic Effects of Different Energy Beta Emitters on Pig Skin

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Abstract
Circular areas of pig skin from 1- to 40-mm diameter were irradiated with .beta. emitters of high, medium, and low energies, 90Sr, 170Tm and 147Pm, respectively. The study provides information for radiological protection problems of localized skin exposures. During the first 16 wk after irradiation 90Sr produced a 1st reaction due to epithelial cell death followed by a 2nd reaction attributable to damage to the dermal blood vessels. 170Tm and 147Pm produced the epithelial reaction only. The epithelial dose response varied as a function of .beta. energy. The doses required to produce moist desquamation in 50% of 15- to 22.5-mm fields (ED50) were 30-45 Gy [grays] from 90Sr, .apprx. 80 Gy from 170Tm, and .apprx. 500 Gy from 147Pm. A model involving different methods of epithelial repopulation is proposed to explain this finding. An area effect was observed in the epithelial response to 90Sr irradiation. The ED50 for moist desquamation ranged from .apprx. 25 Gy for a 40-mm source to .apprx. 450 Gy for a 1-mm source. The 5-, 9- and 19-mm 170Tm sources all produced an ED50 of .apprx. 80 Gy, while the value for the 2-mm source was .apprx. 250 Gy. The area effects evidently could be explained by different modes of epithelial repopulation after irradiation. After high energy .beta. irradiation repopulation would be mainly from the field periphery, while after lower energy irradiation repopulation from hair follicle epithelium would predominate.