A study on the efficient removal of radioactive iodine discharged from patients undergoing thyroid internal therapy.

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K07598
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: Kumamoto University
• Principal Investigator: Ito Shigeki 熊本大学, 大学院生命科学研究部(保), 教授 (80402395)
• Co-Investigator(Kenkyū-buntansha): 桧垣 正吾 東京大学, アイソトープ総合センター, 助教 (50444097)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: α-cyclodextrin / radioactive iodine / thyroid / internal therapy

Outline of Final Research Achievements

We conducted experiments on the retention effect of radioactive iodine using a holding fabric combining 1g of highly absorbent polymer and 5% α-cyclodextrin, with solutions containing radioactive iodine and artificial urine. The tests involved leaving two types of simulated waste solutions containing added radioactive iodine in containers with highly absorbent polymer for 90 days and calculating the residual iodine rate over time through radioactive iodine radioactivity measurement in the simulated waste solution. The residual iodine rate on the 15th day after dehydration was 98% for the aqueous solution and 95% for the artificial urine. It was evident that the highly absorbent polymer combined with α-cyclodextrin could be utilized as a radioactive iodine waste treatment agent for adsorption and separation of radioactive iodine solutions.

Free Research Field

Radiation protection

Academic Significance and Societal Importance of the Research Achievements

従来の放射性廃液一括排水管理による方法は、簡便ではあるが、施設の膨大な改造費用を伴うばかりか、新たな処理法の確立が求められる。CDを用いて、個別に尿中131Iを回収する方法が開発できれば、施設の排水基準等の問題は解消され、131Iの許可使用量増量が可能となり、患者待機期間の大幅短縮から病床稼働率の大幅アップに繋がる。こうした甲状腺内用療法患者の個別管理は、国内のみならず、世界でも一般化できる手法と成り得る。加えて、これらの手法は原子力災害時に即時応用できる。すなわち、これまでの経験則による放射性廃棄物管理から脱却し、学術的根拠に基づく高効率放射性廃棄物管理法構築の突破口となり得る。