ee EVENT AND DESCRIPTION OF EXPOSED GROUPS 9 source’ beam wir doses with comparable biologic effect are obtained: relationship to the surface dose and depth dose as does the air dose measured in a “point source” beam in the clinic or Jaboratory. It would appear under these circumstances and in most experimental conditions that the midline dose, Rongelap. Group I___----Aiinginae, (rroup IJ__2---_Rongerik, Group LIT ____-- rather than dose measured in alr, would be the Utirik, Group IV_.2..------ 26U r 100 r 120 r 20 or 100 3 8 h © <f r | 4e7 EXPOSURE, 2 | < w~SCO MANY SOURCES ra : 135 lamer atone Wi + oO oS = a rs 4 a: RATION 56 ~™NN lad lw a 4 j ] LS nn BILATERAL EXPOSURE, DIVERGING SOURCE . 39% \ OW 10 oN h o 5 iO 15 20 25 30 . 36 CM MASONITE DEPTH OOSE DISTRIBUTION IN CYLINDRICAL PHANTOM, co FACILITY, (NMR?) Fictre 1.4—Counparison of depth dose curves tn maeasontic phantoms fron julateral exposure to d atngle point source, and sunullancous erposure fo minudiiple sources icith a epkerical diugtritution @raund the phantom. better conumon parameter in terms of which to predict biological effect. On this assumption, the air dose values stated in Table 1.1 should be multiphed Gy approximately 1.5 in order to compare their effects to those of a given air dose from a “point source” beam geometry delivered bilaterally. If this is done, assuming a fallout of 12 hours, the following “point wend Cc ch. 481712 O-—%6-——2 The geometry of radiation from a fallout field is not identical either to the geometry of biJateral point sources or spherically distributed sources since the pline source delivers the radiation largely at a erazine angle. However, thie total field situation is better approximated by solid than by plane geometry. Exposure geoim- etry in a radioactive cloud would be spherical.