sparrow: cytogenetic effects of ionizing radiations 



63 



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I 



IONIZATION IN AIR (SIEGBAHN) 



SLOPE OF RANGE CURVE 



— BETHE-BLOCH FORMULA 



2 



8 



10 



12 



14 



16 



18 



ENERGY REMAINING IN KEV 



1 2 3 4 5 6 7 



DISTANCE IN MICRONS FROM END OF RANGE 

 Figure 3. — Rate of energy loss for electrons in water. After Robertson 

 and Hughes (129). 



portions for any radiobiological event requiring more than two 

 ionizations. The radiobiological significance of differences in ioniza- 

 tion density or LET is discussed in Section VIII. 



II. Units of Radioactivity and of Dosage Measurement 



Genetic effects can be produced by ionizing radiation regardless 

 of the origin of the radiation. Today many geneticists use radiations 

 from radioisotopes or nuclear reactors as well as from X-ray machines 

 or accelerators. A list of isotopes used for biological experimentation 



