Dicentric Chromosome Assay

100 dividing cells are examined underneath a microscope after the blood has been drawn and cultured. Typical chromosomes have one centromere holding them together. However, after radiation exposure, many of these chromosomes become dicentric, meaning that they have two centromeres holding the chromosomes together.

Radiation damages DNA. To repair it, the body often ends up forming a second centromere. The percentage of these dicentric chromosomes can tell us about the dose absorbed, down to the lowest level detectable at 0.05Gy. If it has been more than a year since the dose, a Fluorescent in situ hybridisation (FISH) technique is best to detect dicentric chromosomes.