Introduction: The purpose of this study was to evaluate a plastic scintillating plate‑based beam monitoring system to perform quality
assurance (QA) measurements in pencil beam scanning proton beam.
Methods: Single spots and scanned fields were measured with the high‑resolution dosimetry system, consisting of a plastic scintillation
plate coupled to a camera in a dark box at the isocenter. The measurements were taken at 110–190 MeV beam energies with 30°
gantry angle intervals at each energy. Spot positions were determined using the plastic scintillating plate‑based dosimetry system
at the isocenter for 70–230 MeV beam energies with 30° gantry angle intervals. The effect of gantry angle on dose distribution
was also assessed by determining the scanning pattern for daily QA and 25 fields treated with intensity‑modulated proton therapy.
Results: Spot size, field flatness, and field symmetry of plastic scintillating plate‑based dosimetry system were consistent with
EBT3 at all investigated energies and angles. In all investigated energies and angles, the spot size measured was ±10% of the
average size of each energy, the spot position measured was within ±2 mm, field flatness was within ±2%, and field symmetry
was within ±1%. The mean gamma passing rates with the 3%/3 mm gamma criterion of the scanning pattern and 25 fields were
99.2% and 99.8%, respectively.
Conclusions: This system can be effective for QA determinations of spot size, spot position, field flatness, and field symmetry
over 360° of gantry rotation in a time‑ and cost‑effective manner, with spatial resolution comparable to that of EBT3 film.
Jaehyeon Seo, Myonggeun
Yoon*
Department of
Bio-Convergence
Engineering,
Korea University
Kwangzoo
Chung, Youngyih Han, Sung Hwan Ahn*
Department of
Radiation Oncology,
Samsung Medical
Center
Youngyih Han
Department of
Radiation Oncology,
Samsung Medical
Center, Sungkyunkwan
University School
of Medicine, Seoul
Seonghoon
Jeong
Department of
Proton Therapy
Center, National
Cancer Center,
Goyang
Yunhui Jo
Institute
of Global Health
Technology (IGHT),
Korea University
Geon Oh, Yongha Gi, Heehun Sung
Department of BioMedical Engineering,
Korea University,
Seoul, Republic of
Korea
Myonggeun
Yoon*
FieldCure Ltd,
Seoul, Republic of
Korea