UKHSA's Chromosome Dosimetry service relies on assessing the damage to DNA, caused by ionising radiation exposures, in individual blood samples, in order to give an estimation of radiation dose. Radiation exposure scenarios are often complex, so the tests that the CDS carries out are tailored to individual exposure circumstances, on a case by case basis.

What is chromosomal dosimetry?

Ionising radiation can cause direct or indirect damage to DNA, which leads to a complex chain of responses, including activation of DNA damage signalling and repair proteins. Depending on the amount and complexity of damage, chromosome breaks can be repaired or mis-repaired. Mis-repair can lead to chromosome aberrations such as dicentrics (chromosome with two centromeres) or translocations (transfer of DNA material from one chromosome to another).

The Chromosome Dosimetry service can:

  • Demonstrate false alarms when, for example, the dose recorded on a badge was not really received by the wearer
  • Confirm genuine overexposures and provide an alternate estimate of dose independent of any physics methods
  • Give an indication of the whole or partial body nature of the exposure and the proportion of the body exposed
  • Often be the only available method to confirm or refute suspected overexposure to people in a radiation incident who were not wearing dosemeters

Fortunately, the vast majority of cases that have been assessed over the last few years have demonstrated that there has been no over-exposure, so chromosomal dosimetry has been solely for reassurance purposes.