Biodosimetry: an introduction

A measurable biological change in any biological material can be potentially used as an indicator of radiation exposure when either physical dosimeters become unreliable or not available as in most radiological incidents. Biodosimetry tools also plays a major role in dose assortment/assignment for regulatory purpose as in suspected occupational over exposures, effective medical management of exposed individuals as in radiological accidents, and triage as in large scale radiological emergency management. Expectations from these biological indicators are; sensitivity over wide dose range, specificity to radiation exposure with minimal confounds, stability of signal over several months, retrospective analysis, ability to distinguish non-uniform exposure, non-invasive or minimally invasive sample collection, reproducibility of calibration factors, repeatability with multiple sample collections, quick dose estimation and amenable to automation for high-throughput analysis. No single biological indicator suffice all the requirement but classic Dicentric chromosome aberration (DCA) assay has withstood the test of time and being considered as gold standard of Biodosimetry. This assay is highly specific to radiation but also has few limitations such as stability of signal, may not work at high doses and highly labor intensive. Nonetheless, other assays such as Fluorescent in situ hybridization assay, premature chromosome condensation assay, micronucleus assay, γH2AX assay and also many clinical dosimetry methods along with DCA as a multi-parametric approach help us to address all over-exposure scenarios. Biodosimetry lab of HS and EG, BARC has established state of the art facility for addressing the requirements of Biodosimetry analysis and developed many indigenous facilities for achieving high throughput analysis. The lab has also trained, conducted inter-comparison exercises with many national and international-laboratories to gain experience and confidence. In addition to Biodosimetry, clinical applications of these techniques are being explored. Many research projects related to Biodosimetry are being pursued. (author)