Stephen Barnard

Artificial intelligence has recently found its way into biological dosimetry. This study validated the initial version of a deep neural network (DNN) workflow implemented by MetaSystems to detect dicentric and polycentric chromosomes in microscopy images. This was performed through parameter optimisation, calibration curve generation and independent testing. Optimisation of thresholds for the class score parameter defining the aberration classes was performed and brought DNN scoring closer to manual scoring ( ⁶⁰ Co dataset) for low doses by reducing the number of false-positive dicentrics, while balancing the influence of false-negative detections, especially for higher doses. Although slightly higher, the DNN achieved an acceptable yield of dicentrics for the control. A comparison of the calibration curves showed that the DNN curve was between manual and semi-automatic curves. DNN curves based on two independent test datasets (X-ray) from different laboratories showed very good agreement, with dose estimations matching the reference doses for all 12/13 test samples precisely, even for low doses and for triage scoring. This DNN-workflow enables the establishment of calibration curves for different radiation qualities and successfully performs dose estimations. It could replace semi-automated scoring and enhance the capacity of biological dosimetry laboratories in the event of large-scale radiological or nuclear incidents.

Background/Objectives: Chromosome research is essential for advancing our understanding of cytogenetics, gene regulation and numerous aspects of organismal health. Staining chromosomes with 4′,6-diamidino-2-phenylindole (DAPI) and applying Fluorescence Lifetime Imaging Microscopy (FLIM) enables the assessment of structural changes in pericentromeric and heterochromatin-rich region of chromosomes 1, with a shorter fluorescence lifetime (FLT) in the pericentromeric regions compared to the arms. Methods: We used FLIM to optimise sample preparation conditions for more robust imaging and furthermore to measure the impact of low-dose X-ray ionising radiation on chromosome structure when labelled with DAPI. Results: We applied this method to different DNA stains bound to chromosomes where only DAPI led to a clear FLT difference between the chromosome arms (p,q) with 2.98 ± 0.12 ns and 2.65 ± 0.07 ns at the pericentromeric region, while similar stains, such as Hoechst 33258 and NucBlue^TM did not highlight these regions as clearly following FLIM analysis. Our data showed that chromosomes of cells irradiated with 0.1 Gy and 1 Gy did not show a significant change in FLTs (2.94 ± 0.09 ns on the arms and 2.60 ± 0.06 ns on the pericentromeric region) of chromosome 1. Whilst irradiation with 0.5 Gy led to a noticeable and significant reduction in FLT with 2.42 ± 0.13 ns on the arms and 2.12 ± 0.06 ns on the pericentromeric region of HeLa chromosomes. The same pattern could also be seen on X-ray-irradiated T-cell chromosomes. Conclusions: These findings indicate that DAPI FLT may be a useful tool to measure chromosomal structural changes and further suggests that chromosomes undergo distinct structural changes at the pericentromeric region following low-dose irradiation.

From 29th September to 2nd October 2025, European Radiation Protection Week was hosted in London by the UK Health Security Agency with Imperial College London’s Department of Epidemiology and Biostatistics. The meeting brought together the platforms under the MEENAS umbrella (MELODI, EURADOS, EURAMED, NERIS, ALLIANCE, and SHARE) to deliver a diverse programme of presentations and posters spanning the breadth of radiation protection research. This paper provides a summary of the meeting.

Accurately estimating the radiation dose received by an individual is essential for evaluating potential damage caused by exposure to ionizing radiation. Most retrospective dosimetry methods require the time since exposure to be known and rely on calibration curves specific to that time point. In this work, we introduce a novel method tailored to the γ-H2AX assay, which is a protein-based biomarker for radiation exposure, that enables the estimation of both the radiation dose and the time of exposure within a plausible post-exposure interval. Specifically, we extend calibration curves available at two distinct time points by incorporating the biological decay of foci, resulting in a model that captures the joint dependence of foci count on both dose and time. We demonstrate the applicability of this approach using both real-world and simulated data.

Ionizing radiation is mutagenic and carcinogenic, and it is reported to induce primary and secondary tumors with intestinal tumors being one of the most commonly observed. However, the pathological and molecular mechanism(s) underlying the radiation-associated tumorigenesis remain unclear. A link between radiation and somatic tumorigenesis partly through genetic, epigenetic alteration and/or regulation of mismatch repair (MMR) genes has been hypothesized for the first time within this review. Clinical observations and experimental findings provide significant support for this association including MMR mutations as well as altered MMR RNA and protein expressions that occurred post-exposure, although existing evidence in published literature is sparse in this niche area. Some speculative mechanisms are suggested with this review to inform future research. Further studies are needed to understand the roles of the MMR system in response to radiation and to test this possible connection which could potentially provide useful and urgently needed information for clinical guidance.

Background: In trials using normofractionated regimen, the radiation-induced lymphocyte apoptosis (RILA) and the chromosomal damage assays (CDA) have shown prognostic roles of radiation-induced adverse events. The main objectives here were to validate RILA and CDA in extreme and moderate hypofractionation regimens for breast (FAST) and prostate (CHHiP) cancers. Methods: Blood samples were collected from 400 volunteers included in FAST and CHHiP trials. The primary endpoints (PE) were first change in photographic breast appearance and first grade ≥2 RTOG bladder or bowel toxicity (BBT) in FAST and CHHiP, respectively. The secondary endpoints was first grade ≥2 breast clinical changes (BCC) in FAST and BBT using different scales in CHHiP. Results: 103 FAST and 297 CHHiP patients with lab and clinical data were included. In FAST trial, no significant association of RILA with the primary endpoint was observed. A significant association of higher RILA levels with lower risk of any RIAE was found. The risk of developing grade ≥2 RIAE decreased significantly for patients with RILA≥24% compared to those with RILA≤16% with a HR of 0.50 (95%CI 0.25-1.00, p=0.012). Concerning chromosomic aberrations, no significant associations were found with change in photographic breast appearance nor with the secondary endpoint of any RIAE. In CHHiP trial, a decreased risk of grade≥2 RTOG bladder or bowel RIAE was observed for increasing values of RILA (HR 0.97, 95%CI 0.94-1.01, p=0.11) but did not reach statistical significance. Concerning chromosomic aberrations, we found significant association of higher levels of micronuclei per cell with lower risk of gr2+ RTOGAE (p=0.021 for trend test across tertiles; p=0.023 for upper vs lower tertile). Conclusions: This study is the first to evaluate RILA and CDA as predictors of late effects after breast and prostate RT in the “hypofractionation” era. Development of toxicity biomarkers whatever the RT fractionation are urgently needed.

Purpose Cataract (opacification of the ocular lens) is a typical tissue reaction (deterministic effect) following ionizing radiation exposure, for which prevention dose limits have been recommended in the radiation protection system. Manifestations of radiation cataracts can vary among individuals, but such potential individual responses remain uncharacterized. Here we review relevant literature and discuss implications for radiation protection. This review assesses evidence for significant modification of radiation-induced cataractogenesis by age at exposure, sex and genetic factors based on current scientific literature. Conclusions: In addition to obvious physical factors (e.g., dose, dose rate, radiation quality, irradiation volume), potential factors modifying individual responses for radiation cataracts include sex, age and genetics, with comorbidity and coexposures also having important roles. There are indications and preliminary data identifying such potential modifiers of radiation cataract incidence or risk, although no firm conclusions can yet be drawn. Further studies and a consensus on the evidence are needed to gain deeper insights into factors determining individual responses regarding radiation cataracts and the implications for radiation protection.