2022 Fiscal Year Final Research Report

Development of plastic scintillation dosimeter for 4D dose measurement

Research Project

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Project/Area Number	18K15607
Research Category	Grant-in-Aid for Early-Career Scientists
Allocation Type	Multi-year Fund
Review Section	Basic Section 52040:Radiological sciences-related
Research Institution	Chiba University (2021-2022) Tokyo Women's Medical University (2018-2020)
Principal Investigator	Tsuneda Masato 千葉大学, 大学院医学研究院, 特任講師 (60800753)
Project Period (FY)	2018-04-01 – 2023-03-31
Keywords	4D dosimetry / Plastic scintillator / VMAT / SBRT / patient specific QA / dose reconstruction / CCD camera
Outline of Final Research Achievements	To test the measurement technique of the 4D dose distribution measured image by capturing the scintillation light generated using a plastic scintillator and a scintillating screen. Our system constituted a column shaped plastic scintillator covered by a scintillating screen, a conical mirror and a cooled CCD camera. The 3D dose distribution was reconstructed from each captured image using the our original dose reconstruction algorithm. This algorithm includes the blurring correction deconvolution, image scaling, reconstruction and dose conversion. And, we developed the Monte Carlo simulation to compare with the measured 4D dose distribution. We tested the dose linearity, dose rate dependence and gamma analysis for the dose distributions. In this study, our system concept can act as a suitable technique for measuring the 4D dose distribution from the basic characteristic and the gamma results.
Free Research Field	医学物理学、放射線治療技術学
Academic Significance and Societal Importance of the Research Achievements	従来より、高精度放射線治療計画は治療開始前に患者QAとして点線量計測や多次元線量分布検証が行われてきた。しかし、肺や肝臓といった呼吸性移動を伴う部位ではinterplay effectといった腫瘍へ付与される線量の不確定性が生じる問題がある。このような治療においては、同様の患者QAではなく、”腫瘍へ正確に線量付与が行えるプランであるか”を検証する必要がある。そこで、本研究で4次元線量分布計測が可能なシンチレータとCCDカメラを用いたシステムを開発し、そのパフォーマンスを検証した。これに加えて、腫瘍の動きを模擬することで実際に腫瘍へ線量付与が可能であるか、新たな線量評価指標が構築できる。