Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea.
Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
J Cancer Res Ther. 2024 Jan 1;20(1):85-92. doi: 10.4103/jcrt.jcrt_1344_22. Epub 2023 Apr 7.
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.
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.
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.
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.
本研究旨在评估一种基于塑料闪烁板的束流监测系统，以对铅笔束扫描质子束进行质量保证（QA）测量。
在每个能量点，使用由置于等中心暗盒中的塑料闪烁板耦合相机组成的高分辨率剂量测量系统，对单点和扫描野进行测量。在 110-190 MeV 的束能范围内，每隔 30°采集一组数据。在 70-230 MeV 的束能范围内，每隔 30°采集一组数据，使用基于塑料闪烁板的剂量测量系统确定等中心的点位置。还通过确定每日 QA 和 25 个强度调制质子治疗场的扫描模式，评估了机架角度对剂量分布的影响。
在所有研究的能量和角度下，基于塑料闪烁板的剂量测量系统的点大小、射野平坦度和射野对称性均与 EBT3 一致。在所有研究的能量和角度下，测量的点大小均为各能量平均大小的±10%，测量的点位置均在±2mm 以内，射野平坦度均在±2%以内，射野对称性均在±1%以内。扫描模式和 25 个射野的 3%/3mm 伽玛标准的平均伽玛通过率分别为 99.2%和 99.8%。
该系统可以在时间和成本有效的方式下，在 360°机架旋转范围内有效地进行点大小、点位置、射野平坦度和射野对称性的 QA 测定，具有与 EBT3 胶片相当的空间分辨率。
