Assessment of Liquid Radioactive Waste and Radiation Risks Generated from Treated Patients with Isotope I-131 In Nuclear Medicine Units to Improve Medical Waste Management
DOI:
https://doi.org/10.22317/jcms.v11i6.1992Keywords:
Radioactive Waste Disposal, Nuclear Medicine Department, Hospital, Radiation Protection, Iodine Radioisotopes, Iodine-131Abstract
Objective: This study aimed to improve the management of liquid radioactive waste generated from Iodine-131 (I-131) therapy in nuclear medicine facilities. The primary objective was to determine the optimal storage duration required to achieve safe activity levels for environmental discharge, while maintaining compliance with international radiological safety standards and enhancing operational efficiency.
Methods: Liquid radioactive waste samples were collected from decay tanks storing effluents of patients administered I-131 with activities ranging between 3.7 and 7.4 GBq. Activity concentrations were measured at successive half-lives using a high-purity germanium (HPGe) detector, and radiation exposure rates were recorded at 1 m from patients at 1, 24, and 48 hours post-administration. Statistical analyses were conducted to assess decay efficiency, dilution effects, and compliance with the International Atomic Energy Agency (IAEA) and European Union (EU) exemption limits.
Results: The findings revealed a substantial reduction in radionuclide activity after five half-lives (approximately 40 days), with all measurements falling below regulatory clearance thresholds. Radiation dose rates from patients decreased significantly, reaching values below the recommended release limit of 35 μSv/h within 48 hours. Combined effects of natural decay and dilution further minimized radiological risk, confirming the effectiveness of the proposed storage period.
Conclusion: This study demonstrates that storing I-131 liquid radioactive waste for five half-lives is sufficient to ensure radiological safety, thereby eliminating the need for the traditional ten half-life period. Adopting this optimized approach enhances waste management efficiency, reduces storage requirements and costs, and maintains full compliance with international radiation protection guidelines.
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