Ando Yasuharu, Miki Kentaro, Araki Jun, Tsuneda Masato, Kiriu Hiroshi, Nishio Teiji, Nagata Yasushi
Hiroshima City Asa Citizens Hospital, Hiroshima, Japan.
Hiroshima University Hospital, Hiroshima, Japan.
Phys Eng Sci Med. 2021 Mar;44(1):9-21. doi: 10.1007/s13246-020-00946-4. Epub 2020 Nov 18.
In the preparation of intensity-modulated radiation therapy (IMRT), patient-specific verification is widely employed to optimize the treatment. To accurately estimate the accumulated dose and obtain the field-by-field or segment-by-segment verification, an original IMRT verification tool using scintillator light and an analysis workflow was developed in this study. The raw light distribution was calibrated with respect to the irradiated field size dependency and light diffusion in the water. The calibrated distribution was converted to dose quantity and subsequently compared with the results of the clinically employed plan. A criterion of 2-mm dose-to-agreement and 3% dose difference was specified in the gamma analysis with a 10% dose threshold. By applying the light diffusion calibration, the maximum dose difference was corrected from 7.7 cGy to 3.9 cGy around the field edge for a 60 cGy dose, 7 × 7 cm irradiation field, and 10 MV beam energy. Equivalent performance was confirmed in the chromodynamic film. The average dose difference and gamma pass rate of the accumulated dose distributions in six patients were 0.8 ± 4.5 cGy and 97.4%, respectively. In the field-by-field analysis, the average dose difference and gamma pass rate in seven fields of Patient 1 were 0.2 ± 1.2 cGy and 93.9%, respectively. In the segment-by-segment analysis, the average dose difference and gamma pass rate in nine segments of Patient 1 and a 305° gantry angle were - 0.03 ± 0.2 cGy and 93.9%, respectively. This system allowed the simultaneous and independent analysis of each field or segment in the accumulated dose analysis.
在调强放射治疗（IMRT）的准备过程中，广泛采用患者特异性验证来优化治疗。为了准确估计累积剂量并获得逐野或逐段验证，本研究开发了一种使用闪烁体光的原始IMRT验证工具和分析流程。原始光分布针对照射野大小依赖性和水中的光扩散进行了校准。校准后的分布被转换为剂量量，随后与临床使用计划的结果进行比较。在伽马分析中，指定了2毫米剂量一致性和3%剂量差异的标准，剂量阈值为10%。通过应用光扩散校准，对于60 cGy剂量、7×7厘米照射野和10 MV束能量，在野边缘周围的最大剂量差异从7.7 cGy校正到3.9 cGy。在色动力学胶片中证实了等效性能。六名患者累积剂量分布的平均剂量差异和伽马通过率分别为0.8±4.5 cGy和97.4%。在逐野分析中，患者1的七个野的平均剂量差异和伽马通过率分别为0.2±1.2 cGy和93.9%。在逐段分析中，患者1的九个段和305°机架角度的平均剂量差异和伽马通过率分别为-0.03±0.2 cGy和93.9%。该系统允许在累积剂量分析中对每个野或段进行同时且独立的分析。
