Re: Webster Calculation - EDE questions

[Ccja@aol.com]

Sandy

Firstly, I strongly suggest the purchase of a copy of NCRP 122, which is
devoted to the use of the EDE, in these situations.

Then, if you go to 10CFR20.1004, the definition for weighting factor, you'll
find that the fine print under the chart, item #2, reads: "For the purpose of
weighting the external whole body dose (for adding it to the internal dose),
a single weighting factor, wT=1.0 has been specified. The use of other
weighting factors for external exposure will be approved on a case-by-case
basis until such time as specific guidance is issued."
I presume that all Agreement States' regulations contain similar, or
identical, language for this important area of compatibility.

I don't see why there should be a "DDE Head". The whole point of the EDE is
to get away from that sort of thinking, by rationalizing the way in which
highly nonuniform external exposure is estimated, just as it has been for
internal exposure.

Let's say that an individual wears a single badge, outside the apron, at the
collar,and the State-approved weighting factor (it's always going to be the
State, where medical x-rays are concerned, though I don't know what the Navy
does)is 0.3. There should be, on one line, the normal three fields of
reporting, DDE, LDE, and SDE, for the badge identified as the COLLAR, and,
immediately above or below, another line for the ASSIGNED dose (in the column
for the type of record), then, in the NOTES section can go some sort of
shorthand for the means of assignation (eg, type of calculation). Then, the
three readings will be the same, except that in the DDE column would go the
computed EDE (ie, 0.3xcollarDDE).

Our vendor then writes, at the bottom of each page of the report, on which a
given EDE protocol is used, exactly where the four quantities originated. I
think that the collar badge should be used to report the SDE, when two badges
are worn, others may well disagree.

The "Webster" formula is 0.04C+1.5W=EDE, where C and W are the DDE's for the
collar and waist badges, respectively. If somebody's doing something else, it
may well be approved by their regulators, but it's not the "Webster". Note
that the NCRP-recommended weighting factor for a single collar badge is
0.18DDE.

Our only problem has been that our vendor's software doesn't want to assign
EDE's of less than 10 mrem, it calls them "Minimal", as if they were badge
readings. We're working with them to try to correct the matter.

Chris Alston