Nailfold Capillaroscopy and Endothelial Biomarkers in Healthcare Workers Exposed to Chronic Low-Dose Ionizing Radiation

Inclusion Criteria: * Healthcare workers aged between 18 and 60 years. * For the control group: Employment in a healthcare institution with either occupational exposure to low-dose ionizing radiation or no occupational radiation exposure. * For the exposed group: chronic occupational exposure to ionizing radiation for at least 3 years. * Willingness and ability to provide written informed consent. * Ability to comply with study procedures, including nailfold capillaroscopy and blood sample collection. Exclusion Criteria: * History of cardiovascular disease, cerebrovascular disease, or peripheral vascular disease. * Presence of systemic diseases that may affect microvascular structure or endothelial function, including diabetes mellitus, uncontrolled hypertension, dyslipidemia, or chronic kidney disease. * Known autoimmune, connective tissue, or systemic inflammatory diseases (e.g., systemic sclerosis, lupus erythematosus, vasculitis). * Active infection or acute inflammatory condition at the time of enrollment. * Use of systemic medications that may affect endothelial function or microcirculation within the past 4 weeks, including vasodilators, antihypertensive agents, statins, antiplatelet or anticoagulant drugs. * Current smoking or history of smoking within the past 6 months. * Pregnancy or breastfeeding. * History of malignancy or current cancer treatment. * Previous finger trauma, surgery, or local conditions affecting the nailfold area that may interfere with capillaroscopic evaluation.