Dose Estimation Using Dicentric Chromosome Assay and Cytokinesis Block Micronucleus Assay

Abstract

In cases of an accidental overexposure to ionizing radiation, it is essential to estimate the individual absorbed dose of a potentially radiation-exposed person. For this purpose, biological dosimetry can be performed to confirm, complement or even replace physical dosimetry when this proves to be unavailable. The most validated biodosimetry techniques for dose estimation are the dicentric chromosome assay, the "gold standard" for individual dose assessment, and cytokinesis-block micronucleus assay. However, both assays are time consuming and require skilled scorers. In case of large-scale accidents, different strategies have been developed to increase the throughput of cytogenetic service laboratories. These are the decrease of cell numbers to be scored for triage dosimetry; the automation of procedures including the scoring of, for example, aberrant chromosomes and micronuclei; and the establishment of laboratory networks in order to enable mutual assistance if necessary. In this study, the authors compared the accuracy of triage mode biodosimetry by dicentric chromosome analysis and the cytokinesis block micronucleus assay performing both the manual and the automated scoring mode. For dose estimation using dicentric chromosome assay of 10 blind samples irradiated up to 6.4 Gy of x-rays, a number of metaphase spreads were analyzed ranging from 20 up to 50 cells for the manual and from 20 up to 500 cells for the automatic scoring mode. For dose estimation based on the cytokinesis block micronucleus assay, the micronucleus frequency in both 100 and 200 binucleated cells was determined by manual and automatic scoring. The results of both assays and scoring modes were compared and analyzed considering the sensitivity, specificity, and accuracy of dose estimation with regard to the discrimination power of clinically relevant binary categories of exposure doses.

Optimized automated data analysis for the cytokinesis‐block micronucleus assay using imaging flow cytometry for high throughput radiation biodosimetry

“…McNamee et al have previously recommended that 200 BNCs be scored to provide reliable dose estimations (23). Furthermore, in a recent publication De Amicis et al were able to successfully identify doses up to 4 Gy, within 0.5 Gy of the delivered dose by scoring only 100 BNCs (30). The results of this work are consistent with the results of De Amicis et al and demonstrate that scoring approximately 100 BNCs was sufficient to produce accurate dose estimations between 0 and 4 Gy.…”

RABiT-II: Implementation of a High-Throughput Micronucleus Biodosimetry Assay on Commercial Biotech Robotic Systems

“…For high-speed triage purposes IAEA recommends scoring 200 binucleated cells (20), although it was demonstrated that 100 binucleated cells is sufficient to produce accurate dose estimations between 0 and 4.0 Gy (24). Our previously developed protocol (21), based on a 50 μl sample of blood, yielded a dose-dependent average number of binucleated cells between 300 to 1,100 per sample (1,875 mm 2 ) using commercial Metafer 4 software.…”

A Simple Method for Human Whole Blood Microcultures and Its Application in Radiation Biodosimetry

“…Currently, the important improvement is automation of scoring using image analysis software instead of manual visual scoring (De Amicis et al 2014). However, peripheral blood lymphocyte cultivation in vitro is still the essential step in all these established methods above.…”