Establishment of Dicentric Chromosome Analysis for Individual Radiation Biodosimetry in MIDI Format.

Traditionally, the dicentric chromosome assay is performed on large vessels with lymphocyte cultures of 3-5 mL. Our aim was to enhance usability in different settings, focusing on irradiating a thin cell layer to target cells with low-penetration radiation and to handle large-scale triage situations. To achieve this, protocols for irradiation, culture, and metaphase fixation using a MIDI format in 48-well plates were developed. Using 100 μL of isolated lymphocytes in these plates, we systematically optimized cell density, mitogenic stimulation, cell cycle arrest, and metaphase fixation. The semi-automated dicentric scoring with DCSore exhibited a linear-quadratic dose-response relationship up to 8 Gy. This dose-response curve was validated with irradiated and blinded blood samples. The MIDI format provides a reproducible, scaled-down alternative to the classic DCA protocol, enabling exposure of cells to low-penetration radiation and being suitable for both emergency triage and routine biodosimetry.