eee * Ch ne ee Ar rE ipua, J A ne — tai hers ADDENDUM Since the original discussion above was written, further consideration bas been given to the work of Strandgvist and others* on the effect of fractioneticn of doses delivered to the skin end the onset of the observed results. It will be recalled (page 10) thet X-ray doszs to the compared to a one-treatment dose. A log-log plot of total doses versus days after initial treatment yields straight lines. Basically, this means that as doses are being delivered to the skin a certcin rete of repair is taking plece. The over-all effect might be that higher initiel deses from fallout material night be allowsd than if one were to integrate the dose over a period of tine without corsiderstion for the rersir, FEecause of the difference in shapes of tha total beta dose curves for varying times of initial fallout versus Strandgvist X-ray curves the difference between the two curves cannot be expressed as a sinvle relationship. Strandgvist quotes a 1000 roentgen dose in cne treatment to pro~ duce erythoma using X rays {a somewhat smaller mumber than other data quoted ebove), 1250 roentgens if divided into two equal daily éoses, 1450 roontgens if divided into three equal daily doses, etc. O2 course, there are differences between these X-ray doses and beta doses from fallout material such as differences in doses at increasing depth of tissue and the fact that the X rays were delivered essentially as an instantaneous dose at intervals of a day while the beta dose rates are 8 HEREet om ra ng assumed to follow the hee, However, accepting the assumptions of biological equivalence of these roentgen and beta doses and t7le2, *Sievert, Rolf M. "The Tolerance Dose and the Prevention of Injuries Caused By Ionizing Radiations". Y.XX, Na. 236, August 1947. British Journal of Radiology, Lf Pe Heamp + 2NT oe pero o.hee skin were fractionated in equal daily amounts, and the biological effects