[ RadSafe ] Sv (and rems) are NOT restricted to stochastic effects?
Douglas Simpkin
dsimpkin at wi.rr.com
Wed Nov 29 16:24:21 CST 2006
Ron Frick wrote:
>ICRP 60 states: "The equivalent dose is not always the appropriate
quantity >for use in relation to deterministic effects because the
values of radiation >weighting factors have been chosen to reflect
the relative biological >effectiveness (RBE) of the different types
and energies of radiation in >producing stochastic effects.....
I've done a little digging, and while my references are a bit dated,
what the hey, so am I.
According to Herb Attix's book on dosimetry, 1986, the
ICRP-recommended QF for charged particles is related to the collision
stopping power in water. This is referenced as ICRP pub no. 21, 1971,
"Data for protection...against external sources. Supp to ICRP Pub
15." (I do not have the update(s) to this publication to see if
there's any newer definition.) So radiobiology, RBEs, and
deterministic and stochastic biological effects be damned. The QF for
heavy charged particles is defined by physics!
Additionally, Herb quotes from this same ICRP publication that the QF
should be used "...only for routine radiation protection
applications, and should not be used in connection with high level
accidental exposures."
Hmmmm. So here's the fundamental question, the answer to which I
don't know. Is the biological effect of a high dose of alphas the
same as that from a high dose of photons?
Eric Hall ("Radiobiology for the Radiologist" 4th ed. 1994) states
that for another heavy charged particle "[External beams of] Protons
have biological properties similar to x rays," this despite the fact
that the QF for protons is 10.
I'll shut up now and leave confused.
Doug
"I thought I made a mistake once, but I was wrong."
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