RADIATION DEATH IN MAMMALS 



of very high power, the construction of which had ah^eady been begun in 

 1940. The plant operates at a maximum of 50 kV, 2 A tube current 

 (permanently) and supplies up to 1,000, 000 r/min. Irradiation of animals 

 is carried out in rotating plastic containers so as to obtain a homogeneous 

 irradiation. 



The results of these experiments^ led to the recognition of a second 

 effect {i.e. a 7-day effect) which is observed when certain parts of the body 

 are shielded. In the first series of experiments either the head was covered 

 with lead and the trimk alone was irradiated or the trunk was covered with 

 lead and the head alone was exposed. Irradiation of the trunk again gave 

 the 3-5-day effect. With larger doses, however, the survival time decreased 

 more slowly than with whole body irradiation. When only the head is 



moo 



10000 



100000 r 



^ 







7CC0 



10000 



100000 r 



>-, 



lOday 



May 

 70 h 



1\ 



lOmin. 



1m\n. 





-2 



-3 



3 



7(9day 



7 day 

 7^K 



iy\. 



7£'min. 



7min. 



i- 5 3 V 5 



Lo^ doses V Log doses r 



A B 



Figure 3. Survival time of white mice after irradiating the whole body ( ) , and the head only 



(o o) and beginning of convulsions after head irradiation (• •) 



irradiated the entire course of the survival curve was essentially the same 

 as for whole body irradiation, except that the survival time for the dose- 

 independent range was seven days and the range is shortened (approximately 

 from 2,500 r to 1 2,000 r). We were led to conclude that two distinct 

 mechanisms were operating in whole body irradiation in the dose-indepen- 

 dent range of the survival curve. With whole body irradiation a 3-5-day 

 efTect, showing itself more rapidly, naturally hides the 7-day effect, which 

 can only appear if the mechanism leading to the 3 • 5-day effect does not 

 act. If large doses are applied the injuries connected with the 7-day efTect 

 probably come to the fore with a shorter latent period. Furthermore, it 

 would appear that the 3 • 5-day efTect is essentially connected with irradiation 

 of the trunk. Figure 3 represents the results of the tests with white mice 

 described above. 



84 



