Experimental activation assessment of metallic components from medical cyclotron operations in South Korea

Cyclotron-based medical radionuclide production inevitably generates secondary neutrons, which can induce activation in surrounding materials. Despite the growing clinical use of medical cyclotrons, systematic measurements of neutron-induced activation products in the cyclotron components remain scarce. Therefore, this study aimed to perform quantitative measurements of activation in metallic components exposed to secondary neutrons during cyclotron operation. Representative metallic subsamples, including the degraders and target guards, were obtained by mechanically punching circular pieces with a diameter of 6.5 mm from each sample and were systematically categorized in accordance with the measured surface dose rates. High-purity germanium (HPGe) gamma-ray spectrometry was employed to identify and quantify activation products, and specific activities (Bq·g^-1) were calculated for each radionuclide as a function of both subsample type and measurement position. The analysis revealed the presence of radionuclides such as ²²Na, ²⁶Al, ²⁰⁷Bi, and ⁶⁰Co with activity levels strongly dependent on both material type and spatial location relative to the beam target. The findings provide valuable empirical data from actual measurements, establishing a fundamental dataset for understanding neutron-induced activation of cyclotron components and serving as a basis for improving radiation safety management.