Re: Does Size Matter? -Reply

[Michael S Ford <MFORD@pantex.com>]

Martin,  I have also enjoyed this thread a great deal, but disagree
with your closing sentiments.

It would be difficult at best to determine a mass-based
'radiation-effectiveness factor' for a population due to the very myriad
of factors that you mentioned.

And while you noted that a larger mass would present a higher
probability for interaction and subsequent SSBs or DSBs [my
words], that does not take into account a lower fluence for a larger
mass/area/volume [assuming *relatively* uniform human density]
or the efficacy of repair mechanisms when smaller total percentages
of cells are involved.  For larger masses, internal depositions would
also irradiate internal tissues, but at lower concentrations [assuming
larger organs/target tissues].

Hence, larger masses may in fact be more radioresistant than
smaller masses, given the same source term, since the same
amount of energy is deposited into a larger mass (J/kg).

That is, of course, assuming that we are all in agreement on the
definition of the word 'is.'  <grin>

v/r
Michael
mford@pantex.com
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