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How ORISE is Making a Difference

REAC/TS Cytogenetic Biodosimetry Laboratory conducts international exercise to assess radiation dose estimation

Cytogenetics biodosimetry dicentric analysis

ORISE and the Radiation Emergency Assistance Center/Training Site (REAC/TS) recently designed a collaborative chromosome analysis platform to accommodate an international exercise that involved the scoring of abnormal chromosomes used for radiation dose estimation. Cytogeneticists from six international laboratories participated in the exercise scenario, which was coordinated entirely online. The participating labs were spread across four continents in the following six countries: Argentina, Canada, Germany, Great Britain, Japan and the U.S.

The scenario was described as one person receiving an acute, whole-body exposure to a radioactive cobalt-60 source. During the exercise, participants learned that the subject was not wearing a dosimeter and had medical symptoms indicating the likelihood of receiving a significant dose of ionizing radiation.

Cytogeneticists evaluated the samples for abnormal chromosomes, also known as “dicentric” chromosomes, in order to estimate the patient’s radiation dose. To do this, they were provided 810 electronic images to screen of previously irradiated lymphocytes. They were asked to determine which were scoreable and calculate the dicentric yield in order to provide a dose estimate with a lower and upper 95 percent confidence interval. All scorers were blind to the actual dose until after they had submitted their dose estimates to REAC/TS Cytogenetic Biodosimetry Laboratory (CBL). The average estimated dose was within 5 percent of the actual dose to which the sample was irradiated.

The exercise proved very successful and demonstrated that the most labor-intensive step of the method, which was “scoring” of chromosome images, can be reduced dramatically by taking advantage of the Internet. This “dicentric assay” is the “gold standard biodosimetry assay” for estimating radiation dose.

The CBL at REAC/TS was established as part of the nation’s radiological and nuclear response network for the U.S. Department of Energy’s National Nuclear Security Administration. The laboratory is operated in compliance with standards set by the International Atomic Energy Agency (IAEA) and is certified under the Comprehensive Laboratory Improvement Act (CLIA). REAC/TS is a member of the IAEA’s Response Assistance Network (RANET).