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Re: I-131 dose to pregnant woman
Bill -
Warning flags my derriere! How dare you presume this information was
treated as coming from a black box. The verification process has already
been justified and the software validated by experts
Your arrogant esoteric diatribe among that of others is the last straw. I
have commented individually to folks I thought were mis-speaking, but this
one is going to the list. I will not participate in a list that I joined
in hopes of learning and growing my knowledge of radiological issues. And,
not just a little arrogance on my part, you and your ilk are missing out.
I am the kind of participant you should want and you have blown it.
RSAC the program I mentioned is not a 'shielding program' from your
experience. It stands for Radiological Safety Analysis Computer program,
developed, scrutinized, and published for use in determining internal doses
from catastrophic and common events. It has been perfected (incorporating
ICRP, DOE, & NRC guidance) over the last 30 years (unlike the software from
Bill Gates et al).
Incidentally my very knowledgeable colleague has been in the field of
Health Physics for almost 30 years, is member of and advisory participant
on the board of directors of the NRRPT (National Registry of Radiation
Protection Technologists) for most of that time. He is the 'go to guy for
the INEEL Radiological Control organization from Rad Engineers, to Rad Con
Techs, to individual Rad Workers.
The original question or concern did not include the dose recipient's
weight and if the dose was ingested or injected. I was not even certain
the original post meant milli or micro Curies since most e-mail programs do
not transmit the Greek character mu accurately. Yes assumptions were made,
as a science Health Physics is chock full of assumptions.
Based on the fractional depositions for various organs and tissues and dose
delivered resulted in the numbers as shown in the table. These numbers
were verified by individual number crunching with a scientific calculator,
if you need to know the black box in question. The numbers derived from
hard science provide you and the rest of your lot a focal point for you to
make random guesses and unsupported allegations.
Iodine 131 is taken up by the thyroid gland, hence it is a systemic
material. That material is deposited in the recipient's thyroid, however
the radiation emitting from that material (basic but crucial difference) is
a whole body source of radiation.
Bottom line and most important the question was should the women consider
abortion, that is the question.
One last question, why haven't you verified the numbers that waved a flag
at you?
see ya wouldn't want to be ya -
sincerely
helen anna bailly
William V Lipton
<liptonw@DTEENERGY.COM> To: "Michael G. Stabin" <michael.g.stabin@vanderbilt.edu>
Sent by: cc: Peter.Thomas@health.gov.au, radsafe@list.vanderbilt.edu
owner-radsafe@list.vand Fax to:
erbilt.edu Subject: Re: I-131 dose to pregnant woman
08/20/2002 07:22 AM
Please respond to
William V Lipton
Warning flags always go up for me when I read that someone "ran the numbers
through a ... program." This implies that the program is treated as a
black
box, with blind acceptance of the results. The 3 key questions are:
1. How well is the program validated? Even if the program has the "Good
Housekeeping Seal of Approval" from a reputable group, is it being using
within
the range of the validation? (My experience with shielding programs is
that the
results may not be valid for dose rates at the surface of the shielding.)
Does
the user periodically run test cases to verify that the program has not
become
corrupted?
2. Is the input correct for the program requirements (gigo)? Sometimes,
the
assumed units or other parameters are not what the user expects. One
situation
I've run into is the issue of daughter activity. Some programs default to
calculating daughter activities, while some programs do not include
daughter
activities unless the user requests this; e.g., Cs-137 would be treated as
a
pure beta emitter. Although this is probably not a factor, here, there
could be
other "gotcha's" in the program.
3. If this person is "a very knowledgeable colleague," why did he blindly
accept results that are so unusual?
The opinions expressed are strictly mine.
It's not about dose, it's about trust.
Curies forever.
Bill Lipton
liptonw@dteenergy.com
"Michael G. Stabin" wrote:
> > I've basically no experience in this matter but I was rather struck by
> some of
> > the numbers in this table. The 2.4 rem (24 mSv, ca. 24 mGy) to the
uterus
> (and
> > therefore foetus?) seems to agree with what others have suggested. I
note
> > however that the thyroid dose is "only" (quotes indicating my
uneducated
> > reaction) 2.6 rem, most other organs considered in the program seem to
get
> > greater doses. Now my limited education includes the thought that
iodine
> is
> > supposed to concentrate in the thyroid and that the purpose of giving
> I-131 to
> > such a patient is to deliver a dose to the thyroid. The numbers
produced
> below
> > would seem to suggest that in fact it is not very efficient. Why is
this
> so?
> > Anyone care to educate me? (in brief I hope :-) )
>
> In brief, I think the numbers are not very good. The dose to the
esophagus
> and thymus are inexplicably high, and dose to the urinary bladder is way
too
> low, as is the dose to the thyroid, as you note. Carol Marcus suggests
the
> J. Nucl Med article for guidance, and I agree. These are the same numbers
> that I referred you to on the RADAR web page. The article gives doses to
a
> number of organs, with dependence on the degree of hyperthyroidism. The
dose
> to the uterus is representative of the dose to the fetus in the first few
> weeks of pregnancy.
>
> 20% thyroid uptake
> Urinary Bladder 540 mGy
> Ovaries 20 mGy
> Red Marrow 40 mGy
> Thyroid 200,000 mGy
> Uterus 30 mGy
>
> 40% thyroid uptake
> Urinary Bladder 430 mGy
> Ovaries 20 mGy
> Red Marrow 50 mGy
> Thyroid 400,000 mGy
> Uterus 30 mGy
>
> 60% thyroid uptake
> Urinary Bladder 350 mGy
> Ovaries 20 mGy
> Red Marrow 70 mGy
> Thyroid 550,000 mGy
> Uterus 30 mGy
>
> 80% thyroid uptake
> Urinary Bladder 320 mGy
> Ovaries 15 mGy
> Red Marrow 90 mGy
> Thyroid 660,000 mGy
> Uterus 20 mGy
>
> I rounded these to 1 or 2 sig figs, and took a rough average of the
"fast"
> and "slow" thyroid uptake numbers from Table 2 of the JNM article (if you
> want the dose in rads, divide the above numbers by 10). These are just
rough
> estimates for a given patient, more specific thyroid dose calculations
> should be done, but they give you an idea of more reasonable numbers for
the
> other important organs. I will note, however, that the numbers given in
the
> JNM article for fetal dose at later stages of pregnancy are not reliable,
as
> fetal uptake has not been considered. See Health Phys 73(5):756-769, 1997
> for better numbers in later pregnancy.
>
> Mike
>
> Michael G. Stabin, PhD, CHP
> Assistant Professor of Radiology and Radiological Sciences
> Department of Radiology and Radiological Sciences
> Vanderbilt University
> 1161 21st Avenue South
> Nashville, TN 37232-2675
> Phone (615) 343-0068
> Fax (615) 322-3764
> e-mail michael.g.stabin@vanderbilt.edu
> internet www.doseinfo-radar.com
>
> ----- Original Message -----
> From: <Peter.Thomas@health.gov.au>
> To: <radsafe@list.vanderbilt.edu>
> Sent: Monday, August 19, 2002 8:21 PM
> Subject: Re: I-131 dose to pregnant woman
>
> >
> >
> > Peter Thomas
> > ARPANSA
> >
> >
> >
> > I took this question to a very knowledgeable colleague who ran the
numbers
> > through an internal dosimetry program called RSAC using ICRP 39 model
of
> > the human body this is the info he came up with.
> >
>
> >
> >
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