Development of disposable dosimeter for in-vivo measurement of organ at risk during radiation therapy

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K08223
• 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: Kanazawa University
• Principal Investigator: Hayashi Hiroaki 金沢大学, 保健学系, 准教授 (30422794)
• Co-Investigator(Kenkyū-buntansha): 金澤 裕樹 徳島大学, 大学院医歯薬学研究部(医学域), 助教 (80714013) ; 生島 仁史 徳島大学, 大学院医歯薬学研究部(医学域), 教授 (90202861)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 医学物理学 / 放射線線量計 / 子宮頸癌治療 / 密封小線源治療 / 放射線治療 / 精度検証 / インビボ測定 / 直腸線量

Outline of Final Research Achievements

Radiation therapy using 192Ir is used for the treatment of cervical cancer. Since the rectum, which is one of the radiation-sensitive organs, is an organ at risk in this treatment, it is required to control the dose precisely. In this study, we aimed to develop a new rectum dosimeter using an optically stimulated luminescence (OSL) dosimeter and actually measuring the dose during clinical treatment to obtain knowledge about the development of a novel radiation dosimeter and the accuracy of delivered doses during clinical treatment. The hand-made rectum dosimeter was very small and inexpensive, therefore it is suitable for disposable use and is hygienic. For the results obtained in clinical studies, although we experienced a few cases in which differences between the planned and the measured doses become 10% or more, we could analyze the causes.

Free Research Field

医学物理学

Academic Significance and Societal Importance of the Research Achievements

放射線治療時の投与線量は数％の誤差範囲内で決定できていると言われているが，この値は人体模型などを用いて測定した静的な条件下での評価であり，一般的には患者さんに起因する誤差を含んでいない．本研究で行った実測では，患者さんの状態や治療計画に用いるX線画像の質によって，実際の投与線量と計画線量の間に10％を超える差異が生じる可能性があることを明らかにした．この事実は，放射線治療の安全性や危険性を示すものではなく，あくまでも実臨床において，患者さんに起因する誤差要因が入り込む可能性を明示し，またこのような差異を開発した放射線線量計によって検出することができたことは学術的に大変重要である．