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Re: Lymphocyte Culture Lab for Rad Dose Estimate
Carol,
The only commercial laboratory that I'm aware of is in the United Kingdom:
National Radiological Protection Board
E-mail: nrpb@nrpb.org
Web site: www.nrpb.org
Here's some info that I received a short time ago on their technique. If a
whole body exposure, their technique could detect a gamma-ray dose as low
as about 0.1 Gy.
Chromosomal Aberration Dosimetry
This is a brief synopsis and NRPB can provide fuller information, eg.
copies of publications if requested. A small ( 5-10ml ) sample of
heparinised blood can be sent by post or courier to the laboratory and a
minimum of three working days are needed after receipt of the specimen; two
days for cell culturing and one day for microscopy. Metaphases from
T-lymphocytes are prepared and analysed for chromosomal damage caused by
radiation. The dicentric aberration is used to indicate exposure because:
a) it is easily identified; b) it is practically unique to radiation, ie.
no confounding effect of mutagenic chemicals; c) it has a low background
level ( ~ 1 in 1,000 cells ); and d) it has a highly reproducible dose
response relationship that, with a few exceptions, shows little difference
between individuals. The level of effect is dependent on radiation type,
ie., x-rays; gamma-rays; neutrons and therefore a set of dose response
curves, typical of the various radiations commonly encountered in
accidents, has been prepared. With x- and gamma-rays the effect is also
dependent on the time over which the dose is received and whether it is
continuous or intermittent. For unbroken exposures lasting for more than 1
hour or interrupted exposures with gaps of 1 hour or longer some idea of
the likely time course of the exposure is needed.
Because the particular sub-sets of T-cells examined have a fairly
long life-span ( ~ 3 year half-life ) it is possible to carry out the
analysis at considerable times after the irradiation. A sampling delay of
up to 1 year would not seriously prejudice the assay. The lower limit of
dose detection by the chromosomal method is about 100 mGy of x- or
gamma-rays, although at this level there are considerable uncertainties
based on sampling statistics. This is because only 500, or occasionally
1000 cells, are examined. The results of the test are given as the most
likely estimate of averaged whole body dose with 95% confidence limits.
This means that the true dose falls within these limits with at least 95%
certainty. The method gives an estimate of dose from penetrating radiation,
therefore it is not applicable to exposure from soft x-rays or surface
contamination with a or ß particles. Non-uniform or partial body
irradiations may occur. Sometimes an allowance can be made for this by
statistical methods but the technique is not applicable to very localised
exposures, eg. From a very narrow radiation beam or dose just to a hand.
When advising an irradiated person it is worth noting that the
presence of aberrations in the blood lymphocytes is of itself of no health
consequence. Therefore the technique is a biological dosemeter and not a
risk meter. However, it can be inferred that chromosomal damage also would
have been induced elsewhere in the body such as in important stem cells. To
determine a risk of induced cancer from an accidental irradiation, one may
take whatever dose information is available, including that from
chromosomal aberrations and apply risk coefficients such as those
recommended by the International Commission on Radiological Protection.
Advice on such calculations can be obtained from NRPB.
John M. Sukosky, CHP
Dominion
Surry Power Station
(757)-365-2594 (Tieline: 8-798-2594)
Carol Marcus
<csmarcus@ucla.edu> To: radsafe@list.Vanderbilt.Edu
Sent by: cc:
owner-radsafe@list.Van Subject: Lymphocyte Culture Lab for Rad Dose Estimate
derbilt.Edu
04/22/04 10:07 PM
Please respond to
Carol Marcus
April 22, 2004
Dear Radsafers:
Just wondered if any of you know of a reliable laboratory in the USA that
has a lymphocyte culture/chromosome analysis service for estimating
radiation absorbed dose. Or, perhaps there is one in another country.
Much obliged for any help you can give me.
Carol S. Marcus, Ph.D., M.D.
<csmarcus@ucla.edu>
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