Activity Evaluation Methodology for the Disposed Medical Linear Accelerators

For the medical linear accelerators (linac) that utilize more than 10 MV of photon energy, components inside the linac head become radioactivate during the 10-15-year operating cycle. Prior to disposal, radioactive waste must be evaluated for activity, and the same procedure should be followed for medical linacs. In the Republic of Korea, regulation and methodology for the radioactivity evaluation for the medical linac is not established yet. In this study, we employed gamma spectroscopy and a survey meter for evaluating the radioactivity of medical linac components. The components of the Siemens linac considered in this study were classified after decommissioning, and dose rates were measured to up to a 5 cm distance from the component surfaces by using a survey meter. Radionuclides from components were detected using an in situ HPGe detector. Based on the type of radionuclides and dose rate, we estimated the radioactivity of the components. We studied the feasibility of the methodology for disposing of radioactive components by using the in situ HPGe detector.