Introduction: Disaster Preparedness and Emergency Management in Radiation Oncology.

Radiation oncology is uniquely vulnerable to disasters and emergencies because safe treatment depends on specialized infrastructure, accurate treatment-state information, coordinated multidisciplinary workflows, and continuity across multiple fractions. Disaster preparedness and emergency management are therefore core components of safe, timely, and effective cancer care rather than separate administrative obligations. In radiation oncology, emergency management includes acute clinical events and immediate operational response, whereas disaster preparedness includes mitigation, continuity planning, recovery planning, and institutional learning after large-scale or sustained disruptions. Natural disasters, cyberattacks, pandemics, equipment failures, medical emergencies, and infrastructure interruptions differ in mechanism but converge on a common operational problem: how to continue time-sensitive, technically complex treatment when usual systems are unavailable. This special issue examines that problem from multiple perspectives, including acute medical emergencies during treatment, MR-specific safety hazards, incident reporting, cyber resilience, workflow redundancy, software tools, natural disasters, pandemic planning, ethical decision-making, trainee roles, and resilient system design. Across these topics, several themes emerge. Generic health care emergency plans must be translated into radiation oncology-specific workflows. Business continuity must become treatment continuity; data backup must become usable treatment-state knowledge; and facility resilience must include safe recommissioning and quality assurance. Preparedness also requires trained personnel, clear authority, scalable plans across practice settings, tested downtime procedures, communication pathways, transfer agreements, recovery processes, and post-event learning. Ultimately, continuity of radiotherapy should be regarded as a clinical outcome worthy of deliberate protection across the care continuum.