INFLUENCE OF LINEAR ENERGY TRANSFER 



321 



stopping power of tissue (approximately that of liquid water) to the 

 stopping power of air. The result is the energy absorption per unit 

 volume. 



When radon is introduced into the culture medium, the determination 

 of energy absorption in the biological material can be determined only by 

 taking precautions too numerous and complicated to detail here (Zirkle, 

 1936). Gray and Read (1942) have discussed and thoroughly investi- 

 gated this matter. 



RESULTS OF THE AVAILABLE INVESTIGATIONS 



In view of the large number of pertinent investigations, no attempt 

 will be made to discuss any of them in detail. The results are tabulated 

 in Table 6-1. In Figs. 6-1 and 6-2 are plotted the results of investiga- 

 tions which covered wide variation of LET. 



to 



CD 



O 



LU 

 U. 

 U. 

 UJ 



< 



o 



CD 

 O 



_i 



o 



m 



u 

 > 





VEGETATIVE BACTERIA 

 y [Ecoli) 



0.2 05 I 2 5 10 20 50 100 200 



LINEAR ENERGY TRANSFER, kev/yy 

 Fig. 6-1. Variation of biological effectiveness with linear energy transfer (LET). 

 Further data in Table 6-1 as follows: haploid yeast, item 23; diploid yeast, item 22; 

 vegetative bacteria, item 16; bacterial spores, item 17; fibroblasts, item 46. 



