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Descrizione
Whole brain radiotherapy (WBRT) remains an essential treatment for brain metastases and primary intracranial malignancies, but conventional radiotherapy (CONV-RT) incidentally exposes ocular structures to radiation, potentially leading to vision-threatening complications. FLASH radiotherapy (FLASH-RT) delivers ultra-high dose rates (≥40 Gy/s) in milliseconds, compared to CONV-RT where the dose delivery is ≤1 Gy/min over several minutes. This study aims to evaluate comparative effects of FLASH-RT versus CONV-RT on corneal collagen morphology using second-harmonic generation (SHG) imaging in a murine WBRT model. C57BL/6J wild type mice were assigned to control, FLASH-RT, and CONV-RT groups and evaluated acutely (4 days) and chronically (40 days) post irradiation at 20, 15 and 10 Gy, respectively. SHG microscopy quantified collagen organization using forward-to-backward (F/B) signal ratios and assessed corneal thickness as markers of radiation-induced damage. In CONV-RT we found significantly decreased F/B ratios compared to controls (p < 0.05), indicating substantial collagen disorganization, and increased corneal thickness, due edema and inflammation. Conversely, FLASH-RT maintained F/B ratios comparable to controls and prevented excessive thickening of the cornea, demonstrating preserved extracellular matrix integrity across both timepoints. FLASH-RT preserves corneal collagen architecture compared to CONV-RT during whole brain irradiation, demonstrating significant potential for minimizing ocular toxicity in WBRT. These findings support clinical investigation of FLASH-RT as a tissue-sparing modality for brain cancer treatment
