Context (TH): Following a radiological event, like a nuclear reactor accident or a dirty bomb detonation, identifying individuals with significant radiation exposure is crucial for timely medical intervention.
What is Biodosimetry?
Biodosimetry determines radiation exposure by analysing biological changes in blood, urine, or hair samples. It is useful when exposed individuals don’t have personal radiation monitoring devices.
Traditional Biodosimetry Techniques
Dicentric Chromosome Assay (DCA)
Considered the “gold standard,” this method measures chromosomal aberrations in white blood cells.
It is specific and sensitive but labour-intensive, limiting its use in large-scale events.
Cytokinesis-Block Micronucleus Assay (CBMN)
It detects micronuclei formed due to DNA ejection during cell division after radiation exposure.
While faster than DCA, it also requires longer cell culturing and takes about three days for results.
Gamma-H2AX assay
It measures phosphorylated histone proteins and provides results within 6-8 hours without cell culturing. It must be performed within 24 hours of exposure due to the dynamics of histone phosphorylation.
High-Throughput Biodosimetry with Automation
Rapid Automated Biodosimetry Tool (RABiT)
Columbia University developed RABiT, Which automates biodosimetry assays using 96-well plates, significantly increasing sample processing compared to manual methods.
High Throughput Screening (HTS) Platforms
RABiT-II utilises commercially available HTS platforms for automating CBMN and DCA assays.
These platforms offer:
Increased Throughput: Each machine can analyse thousands of samples per day.
Improved Reliability: Rigorous quality control ensures reliable data generation.
Wider Availability: Existing personnel and infrastructure facilitate deployment during a crisis.
Premature Chromosome Condensation (PCC):This technique condenses chromosomeswithout culturing, potentially providing same-day dose estimates using the DCA assay.
Biodosimetry in a Two-Tier Triage System
To manage the high volume of people requiring testing, a two-tier triage system is envisioned
A rapid Point-of-Care (POC) biodosimetry assay at the CRC, providing a binary (exposed/not exposed) result within 30 minutes.
A hospital- or lab-based biodosimetry assay, such as DCA or CBMN on an HTS platform, for individuals identified as exposed by the POC test. This more precise test determines specific dose levels and assigns individuals to appropriate treatment categories.