Re: rem vs. rad

[browndr@nist.gov]

>I think we're asking the wrong question.  Instead of basing the cutoff on
>dose, base it on effect.  Use rem for ANY dose when estimating stochastic
>risks.  Even if the dose is high, if I want a stochastic risk estimate, I
>have to use rem (would you try to estimate cancer risk using rads?).  As
>Bob Flood pointed out, the whole stochastic risk model - complete with
>radiation weighting factors (ie.Q) was "founded" on high doses, and if
>I'm estimating risk for a stochastic effect, by definition I have to use
>rem. For non-stochastic effects, one should use rad to determine, for
>instance if the dose is above the threshold for some particular effect.  
>Example:  I rapidly get 400 rem uniform whole body dose (just to make it
>interesting, it's from neutrons with Q=2, so absorbed dose is 200 rad). 
>To estimate my cancer risk, I use rem.  To evaluate the potential for and
>severity of a non-stochastic effect, I use rad.


I think the problem with this may lie in the basis for the determination
of the Q values......At what dose rates have the Q values been evaluated
for, aren't these somewhat dose  rate dependent, especially for higher(??)
dose rates.

Regards,

Dave Brown, chp
NIST Reactor Health Physics
Gaithersburg, MD
301-975-5810
browndr@nist.gov

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