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BACKGROUND AND AIM: About 22,000,000 Curies of radioactive xenon-133 escaped into the environment following the 1979 accident at the Three Mile Island nuclear power station in Pennsylvania. Anecdotal evidence of symptoms consistent with radiation exposure were contemporaneously reported, and a limited biodosimetric investigation performed in 1994 produced evidence consistent with significant radiation exposure. Subsequent epidemiological investigations have produced equivocal findings. We aim to re-assess the impact of the unique TMI exposure using a state-of-the-art method of cytogenomic analysis by joining, for the first time, the recently proposed physics of radiobiological shot noise with environmental epidemiology. METHODS: We employ a modern cytogenomics technology for evaluation of radiation-induced DNA damage. Our innovative technology is known as directional genomic hybridization (dGH). The dGH methodology enables high-resolution detection of both translocations and inversions, which when symmetrical are stable biomarkers of prior radiation exposure. The strand-specificity of the dGH methodology enables detection of inversions at much higher resolution than was possible previously, while simultaneously also detecting translocations. Inversions are induced at a greater rate than are translocations, creating a more sensitive "biodosimeter". The detection power of the approach is enhanced by employing five colors to paint all twenty-three chromosome pairs, while adding automation using artificial intelligence and machine learning to speed aberration scoring. RESULTS AND CONCLUSIONS: Based on preliminary data from four exposed and four unexposed individuals, matched for location, age, and sex, we have demonstrated the feasibility of our approach. Although at the present time no inference regarding the degree of exposure can be supported, representative images demonstrating the resolution of the dGH technology will be presented. We have laid the foundation for a larger study of TMI-exposed individuals to come. Our approach may evolve to become the new standard for quality and sensitivity in retrospective biodosimetry. KEYWORDS: biodosimetry, cytogenetics, ionizing radiation