REAC/TS' Cytogenetic Biodosimetry Laboratory is a critical resource in the event of mass casualties involving radiological or nuclear materials

By operating a cytogenetic biodosimetry laboratory (CBL), the Oak Ridge Institute for Science and Education (ORISE) is helping the U.S. Department of Energy close a critical gap in our nation’s ability to respond to a radiological or nuclear incident. The use of radiation for medical, industrial, research and other applications raises the risk of accidental human exposure. In addition, the growing threat of radiological/nuclear terrorism poses a serious risk to human health and welfare. Should there be an incident involving radiological or nuclear materials that affects a large population, cytogenetic biodosimetry is a proven technique that can be used to help calculate the absorbed radiation dose in exposed individuals. Information on individualized radiation dose assists in better treatment decisions and better management of valuable emergency response resources.

The CBL at the Radiation Emergency Assistance Center/Training Site (REAC/TS) performs the individualized radiation dose assessment using the “gold standard” dicentric chromosome assay. Currently, the CBL is the only federally funded facility certified by Clinical Laboratory Improvement Amendments (CLIA). The CBL has also been successful in obtaining the ISO9001 certification for quality and performance each year. The REAC/TS CBL is a collaborating partner for the World Health Organization (WHO) and is one of the actively participating laboratories in annually conducted international comparative studies that are aimed to verify and validate the quality of radiation dose assessment.

Recently, the CBL has initiated the development of high throughput platforms for many of the cytogenetic applications and novel biomarkers, which will enable rapid dose assessment of individuals in case of mass casualty incidents. The CBL is fully equipped to perform state-of-the-art techniques, such as multicolor fluorescence in situ hybridization (FISH), which are useful in monitoring and predicting the long-term effects of ionizing radiation in exposed individuals (see example below).

Fluorescence in situ hybridization (FISH) is useful in monitoring and predicting the long-term effects of ionizing radiation in exposed individuals

How cytogenetic biodosimetry works 

Cytogenetic biodosimetry measures the response of circulating blood lymphocytes in  the human body to accurately estimate the absorbed radiation dose. When energy associated with ionizing forms of radiation is transferred to atoms and molecules in human cells and tissues, damage is induced in the chromosomal DNA depending on the type and amount of energy of the absorbed radiation.

Dicentric chromosome formation

Several types of chromosomal aberrations can be induced by ionizing radiation exposure. One type of aberration is known as a dicentric chromosome, which is a fusion of two chromosomes after DNA breakage, and has been shown to be highly specific for radiation exposure. Since dicentric chromosome formation depends on radiation dose, absorbed whole body dose can easily be estimated from the frequency of dicentric chromosomes fitted to a calibration curve with known doses of radiation. This strategy for dose estimation is valid because lymphocytes express the chromosomal damage for a reasonable length of time (approximately 30 days) after radiation exposure.

The dicentric chromosome assay enables ORISE’s cytogenetics researchers to quantify chromosomal DNA damage and provide an accurate dose estimate for patients who need immediate and specialized medical care. This valuable tool allows decision makers and public health officials to assess the magnitude of exposure for better allocation of resources.

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