FW: some details on the criticality in Japan

["Carroll,Raymond" <carrollrg@pgdp.usec.com>]

Doug,

In response to your first question, 8-10 Sv (which should actually be
expressed as 8-10 Gy) would be expected to result in the symptoms reported.
The major difference between the accident doses and the doses and symptoms
you are used to is the difference between localized irradiation and whole
body irradiation.  If you were to irradiate your patient's whole body as
opposed to localized areas of the body you should see the same symptoms.
The doses you are giving patients would be lethal doses if the whole body
was irradiated.  (Helps heighten the importance of careful treatment
techniques and radiological safety doesn't it?)

Ray Carroll
carrollrg@pgdp.usec.com
____________________________________________

Doug wrote:
-------------------------
Greetings,

May I ask for some information that may help some of us understand the doses
better.  (I am mostly involved in total body irradiation for leukemia ...)
In medical TBI treatments a beam of 6-10 MV x-rays is used with doses of
250-300 cGy are commonly given (split between two exposures) per day to a
total of between 900 - 1200 cGy (depending upon institutional preferences).
Based upon my observations of these patients over the years, I am suprized
to
be hearing that 6-8 Sv in one exposure of less than one hour can cause death
within 6 hours or severe cns (etc.) symptoms within 8 hours.  Admittedly, I
have dealt only in fractionated x-ray (medical) exposures.  My questions are
(for this type of event) :
1) What is the likely dose to the three persons described in the media
reports ?
(6-8 Sv does not seem to be consistant with the reported symptoms.)
2) What are the likely photon and neutron dose components ?
3) What is the likely "x-ray" equivalent photon spectra ?
4) What is the likely neutron energy distribution ?

Just a "medical-type" trying to better understand a non-medical type event.

Doug J.
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