Biological dosimetry by the triage dicentric chromosome assay e Further
validation of international networking
Ruth C. Wilkins
a
,
*
, Horst Romm
b
, Ursula Oestreicher
b
, Leonora Marro
a
, Mitsuaki A. Yoshida
c
,
d
, Y. Suto
c
,
Pataje G.S. Prasanna
e
a
Health Canada, Ottawa, ON K1A 0K9, Canada
b
Bundesamt fur Strahlenschutz, 38226 Salzgitter, Germany
c
Biological Dosimetry Section, Dept. of Dose Assessment, Research Center for Radiation Emergency Medicine, NIRS, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
d
Department Radiation Biology, Institute of Radiation Emergency Medicine, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
e
National Cancer Institute, Division of Cancer Treatment and Diagnosis, Radiation Research Program, 6130 Executive Blvd., MSC 7440, Bethesda, MD 20892-7440, USA
article info
Article history:
Received 22 November 2010
Received in revised form
9 March 2011
Accepted 15 March 2011
Keywords:
Biological dosimetry
Dicentric chromosome assay
International networking
Emergency response
Triage
abstract
Biological dosimetry is an essential tool for estimating radiation doses received to personnel when
physical dosimetry is not available or inadequate. The current preferred biodosimetry method is based
on the measurement of radiation-specific dicentric chromosomes in exposed individuals’ peripheral
blood lymphocytes. However, this method is labor-, time- and expertise-demanding. Consequently, for
mass casualty applications, strategies have been developed to increase its throughput. One such strategy
is to develop validated cytogenetic biodosimetry laboratory networks, both national and international. In
a previous study, the dicentric chromosome assay (DCA) was validated in our cytogenetic biodosimetry
network involving five geographically dispersed laboratories. A complementary strategy to further
enhance the throughput of the DCA among inter-laboratory networks is to use a triage DCA where dose
assessments are made by truncating the labor-demanding and time-consuming metaphase spread
analysis to 20 e 50 metaphase spreads instead of routine 500 e 1000 metaphase spread analysis. Our
laboratory network also validated this triage DCA, however, these dose estimates were made using
calibration curves generated in each laboratory from the blood samples irradiated in a single laboratory.
In an emergency situation, dose estimates made using pre-existing calibration curves which may vary
according to radiation type and dose rate and therefore influence the assessed dose. Here, we analyze the
effect of using a pre-existing calibration curve on assessed dose among our network laboratories. The
dose estimates were made by analyzing 1000 metaphase spreads as well as triage quality scoring and
compared to actual physical doses applied to the samples for validation. The dose estimates in the
laboratory partners were in good agreement with the applied physical doses and determined to be
adequate for guidance in the treatment of acute radiation syndrome.
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
Accurate dose estimates can be made by biological dosimetry to
predict acute radiation syndrome (ARS) within days after a radia-
tion accident or a malicious act involving radiation. Timely infor-
mation on dose is quintessential for the medical management of
acutely irradiated personnel (IAEA, 2001; Waselenko et al., 2004;
Coleman et al., 2009; Weinstock et al., 2008).
The dicentric chromosome assay (DCA) provides dose estimates
to acutely irradiated personnel based on the frequency of radiation-
specific dicentric chromosomes in irradiated persons’ peripheral
blood lymphocytes. DCA is very sensitive due to a low and stable
background dicentric frequency (1e2 per 1000 metaphase spreads).
Laboratory protocols have been standardized by the International
Organization for Standardization (Voisin et al., 2002; ISO, 2004) and
dose levels as low as 0.1e0.2 Gy can be detected, when 500e1000
metaphase spreads are analyzed (IAEA, 2001).
Analysis of 500e1000 metaphase spreads per irradiated subject,
however, is neither practical as it is labor-intensive, nor essential in
a radiation mass casualty event, where acute risk of ARS develop-
ment needs to be assessed for potentially a large number of indi-
viduals for making treatment decisions. Therefore, in these
situations, the precision on estimated doses may be decreased to
improve throughput by reducing the number of metaphases
*
Corresponding author.
E-mail address: Ruth.Wilkins@hc-sc.gc.ca (R.C. Wilkins).
Contents lists available at ScienceDirect
Radiation Measurements
journal homepage: www.elsevier.com/locate/radmeas
1350-4487/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.radmeas.2011.03.012
Radiation Measurements 46 (2011) 923e928