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Re: rem vs. rad -Reply

Charlie's message is an important one; the distinction between quantities
and units bears reitieration.  The rem is an (archaic) unit that is used to
characterize the magnitude of a number of different quantities, eg whole
body dose equivalent; organ dose equivalent; effectived dose; committed
effective dose; etc.  One needs to specify the quantity that is being
characterized, something which regrettably regulators (especially) as well
as ordinary mortals and even CHP's frequently neglect to do.

The rem is not the only unit used to characterize different quantitites; the
gram (gramme in French) is commonly used to quantify both weight and mass;
an astronaut on the moon has the same mass in g as on earth, but the weight
is considerably different.  

Ron Kathren, CHP


  At 06:50 PM 4/2/98 -0600, Charles Willis wrote:
>Otto, et al.
>There is a potential for confusion here.  Rem can mean the dose in rad
>by the radiation weighting factor or it can mean rad times radiation
weighting factor
>time tissue weighting factor.  Furthermore, the unit is the same whether
you use
>the tissue weighting factors from ICRP-26 or those from ICRP-60.  The tissue
>weighting factors are based on (better, guessed-at considering) the ICRP's
>stochastic detriment.  For any other end-point, they are even more wrong.
>When interested in deterministic effects, clearly there is a need to
recognize that
>some radiations are more effective than others (per unit dose) but the
>weighting factors for deterministic effects certainly are different from
those for
>stochastic affects.  This was an interesting area of study when nuclear war
was of
>greater concern but it isn't popular now.
>Charlie Willis