Radioactivation and Decommissioning of Medical Linear Accelerators: A Review.

Medical linear accelerators (LINACs) operating above 8-10 MV produce induced radioactivity in machine components and treatment vault structures through photonuclear reactions and subsequent neutron capture. As the global installed base of LINACs exceeds 14,000 units and demand continues to grow, an increasing number of machines are reaching end-of-life, making the safe disposal of radioactivated components a pressing practical concern for healthcare institutions. This review covers the radioactivation process in medical LINACs, beginning with the physics of photonuclear interactions and neutron capture, including the giant dipole resonance and electronuclear reactions. The principal radionuclides identified in LINAC components and treatment room concrete are compiled from published measurements and Monte Carlo simulations across multiple vendors (Varian, Elekta, Siemens). The current regulatory frameworks governing the disposal of activated materials are compared, covering the International Atomic Energy Agency (IAEA) standards (GSR Part 3, GSG-17, GSG-18), the U.S. Nuclear Regulatory Commission (NRC) regulations (10 CFR Parts 20 and 61), the European Union Basic Safety Standards (Directive 2013/59/Euratom), and South Korea's Nuclear Safety and Security Commission (NSSC) Notice No. 2025-11, which establishes nuclide-specific clearance levels for self-disposal (the Korean regulatory equivalent of the IAEA concept of clearance) aligned with the IAEA's 10 µSv y-1 dose criterion. A practical step-by-step protocol for the disposal of radioactivated LINAC components is proposed to assist hospitals in achieving safe, compliant, and cost-effective waste management.