On the difference between reference radiations used in radiobiology.
OBJECTIVE
To add further support to the designation of hard gamma-rays, such as those emitted by (60)Co or (137)Cs, as the common reference radiation, as recommended by the International Commission on Radiological Protection (ICRP) Task Group 37 in the recent ICRP Publication 92.


METHODS
The study examined the microdosimetric properties of seven commonly used reference radiations and quantified differences in radiation quality among them. The principal tool is the proximity function, which is derived from the spatial distributions of energy deposits calculated by Monte Carlo simulations.


RESULTS
The microdosimetric properties of the seven commonly used reference radiations were significantly different. However, there were no significant differences in the spectra of energy deposition in microscopic regions between hard gamma-rays over a wide range of distances of biological interest.


CONCLUSIONS
From a microdosimetric point of view, gamma-rays from (60)Co or (137)Cs are the most suitable reference radiations for specification of the relative biological effectiveness.
Chen
J
J
Radiation Protection Bureau, Health Canada 6302D1, 775 Brookfield Road, Ottawa K1A 1C1, Canada. jing_chen@hc-sc.gc.ca
D005720:Gamma Rays; D009010:Monte Carlo Method; D011835:Radiation Protection; D011853:Radiobiology; D011874:Radiometry; D012062:Relative Biological Effectiveness