Establishing a Reference Dose–Response Calibration Curve for Dicentric Chromosome Aberrations to Assess Accidental Radiation Exposure in Saudi Arabia

Abstract

In cases of nuclear and radiological accidents, public health and emergency response need to assess the magnitude of radiation exposure regardless of whether they arise from disaster, negligence, or deliberate act. Here we report the establishment of a national reference dose–response calibration curve (DRCC) for dicentric chromosome (DC), prerequisite to assess radiation doses received in accidental exposures. Peripheral blood samples were collected from 10 volunteers (aged 20–40 years, median = 29 years) of both sexes (three females and seven males). Blood samples, cytogenetic preparation, and analysis followed the International Atomic Energy Agency EPR-Biodosimetry 2011 report. Irradiations were performed using 320 kVp X-rays. Metafer system was used for automated and assisted (elimination of false-positives and inclusion of true-positives) metaphases findings and DC scoring. DC yields were fit to a linear–quadratic model. Results of the assisted DRCC showed some variations among individuals that were not statistically significant (homogeneity test, P = 0.66). There was no effect of age or sex (P > 0.05). To obtain representative national DRCC, data of all volunteers were pooled together and analyzed. The fitted parameters of the radiation-induced DC curve were as follows: Y = 0.0020 (±0.0002) + 0.0369 (±0.0019) *D + 0.0689 (±0.0009) *D2. The high significance of the fitted coefficients (z-test, P < 0.0001), along with the close to 1.0 p-value of the Poisson-based goodness of fit (χ2 = 3.51, degrees of freedom = 7, P = 0.83), indicated excellent fitting with no trend toward lack of fit. The curve was in the middle range of DRCCs published in other populations. The automated DRCC over and under estimated DCs at low (<1 Gy) and high (>2 Gy) doses, respectively, with a significant lack of goodness of fit (P < 0.0001). In conclusion, we have established the reference DRCC for DCs induced by 320 kVp X-rays. There was no effect of age or sex in this cohort of 10 young adults. Although the calibration curve obtained by the automated (unsupervised) scoring misrepresented dicentric yields at low and high doses, it can potentially be useful for triage mode to segregate between false-positive and near 2-Gy exposures from seriously irradiated individuals who require hospitalization.

Dicentric chromosome assay using a deep learning-based automated system

“…However, automated scoring data show that the number of dicentric chromosomes increases radiation dose-dependently but does not always follow the Poisson distribution. Several trials have been conducted to facilitate dose–response curve generation, such as using different models 27 or an expert review process for selecting whole cells with 46 chromosomes 28 . Furthermore, the final result is more accurate because experts confirm the dicentric chromosome candidates 21 .…”

Linear Dose Response of Acrocentric Chromosome Associations (Aca) To Gamma Irradiation In Human Lymphocytes

“…The latest study by Alsbeigh et al, [48], highlighted the observation that DC is underestimated in accidental radiation exposures with doses of less than 1 Gy, wherein lies an impending risk of developing late stochastic effects [49]. Since it is a fact that physical inter-chromosomal connections in ACA are the rst to break during genomic instability [14], the parameter captured our attention and the results of the present analysis are indicative that ACA can serve as a precise and sensitive tool for generating biodosimetry curves, especially for low dose ionizing radiation exposure.…”

Assessment and treatment requirements of public hospitals to radiation emergencies

“…DCA is the optimal biodosimetry technique when blood samples are collected in less than 2 months after irradiation [13], it is standardized by ISO at all reference biodosimetry laboratories [14] and is alone recommended as the reference technique by the IAEA [15]. DCA requires significant technical expertise and is time consuming, requiring at least 3-5 days after sampling, thus making non-applicable dosimetric requirements on an emergency basis, but is very sensitive and specific even at doses as low as 0.05 Gy [16].…”