Going back in time with biological dosimetry

From the IAEA Division of Human Health, Applied Radiation Biology and Radiotherapy Section

We know that it is important to always measure and control dose of exposure to radiation and there are professionals who are specialised in ensuring that radiation protection procedures are rigorously followed. But what happens when there are accidents? Or the patient's data is not immediately available to provide this important information? In spite of strict regulations and safety measures, radiation/nuclear accidents or unplanned radiation exposures may occur. So is it possible to go back in time to determine the radiation dose individuals were exposed to? This is the key factor that biological dosimetry aims to address.

Biological dosimetry uses biological samples, like blood, usually taken from individuals who have been exposed to radioactive materials, as a way to assess intake for example by inhalation or ingestion. In the event of a radiation / nuclear emergency, biological dosimetry is essential for timely determination of the radiation dose to the exposed individuals (i.e. exposed workers and general public).

Biological dosimetry helps to reconstruct the dose of radiation received by an individual or patient. This method uses biological markers such as chromosomal abnormalities, which can be seen using a conventional or fluorescent microscope.

Retrospective biological dosimetry may even help reveal radiation exposure received many years ago, like in the case of the Chernobyl accident or atomic bombings of Hiroshima and Nagasaki.

Biological dosimetry might also be used for clinical applications, such as helping radiation oncologist to improve medical outcome.

Human chromosomes painted with special molecular probes to reveal chromosomal damage and show radiation exposure. (Photo: Prof. Hande, National University of Singapore)

A pair of human chromosomes showing a unique 'intra-chromosomal inversion', which is considered a specific sign of radiation exposure. This kind of abnormality was found in workers of the 'Mayak' nuclear reprocessing plant in Russia. (Photo: Prof. Hande, National University of Singapore)

A new method of biological dosimetry, which is colouring ends and central parts of chromosomes, so markers of radiation exposure 'dicentrics' can be revealed easier. (Photo: Prof. Hande, National University of Singapore)