Optimization of Subcellular Boron Distribution Measurement Using UV-C Imprint and Neutron Autoradiography in Boron Neutron Capture Therapy

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The subcellular distribution of boron drugs is crucial for studying radiobiological effects and microdosimetry in boron neutron capture therapy (BNCT). Accurately measuring this distribution remains a key objective. Building on the neutron autoradiography method combined with UV-C sensitization, this study aims to further optimize the approach and implement it at the BNCT center of Xiamen Humanity Hospital, with the expectation of applying it to future boron drug development. A dedicated irradiation device for neutron autoradiography was developed based on a clinical epithermal neutron beam. Optimal conditions for etching and UV-C cell imprints were investigated. After U251 cells were incubated with L-4-boronophenylalanin (BPA), cell imprints and track images were obtained under optimal conditions, and track distributions within cell structure were evaluated. The optimal etching condition involved using Potassium-Ethanol-Water (PEW) solution for 10 min, yielding track diameters of approximately 1 μm. After the poly allyl diglycol carbonate (PADC) with cultured cells was exposed to UV-C for 12 h, a clear cellular structure was imprinted on the PADC. The coupled track and cell structure images suggest that BPA may concentrate more around the U251 cell nucleus. The results demonstrate that the improved method can clearly distinguish tracks within the nucleus and cytoplasm in two-dimensional projections, enabling a more accurate evaluation of boron distribution at the subcellular scale.