Nitta Yuya, Ueda Yoshihiro, Isono Masaru, Ohira Shingo, Masaoka Akira, Karino Tsukasa, Inui Shoki, Miyazaki Masayoshi, Teshima Teruki
Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan.
Department of Radiology, Osaka Women's and Children's Hospital, Osaka, Japan.
J Med Phys. 2021 Apr-Jun;46(2):66-72. doi: 10.4103/jmp.JMP_76_20. Epub 2021 Aug 7.
To evaluate customizing a knowledge-based planning (KBP) model using dosimetric analysis for volumetric modulated arc therapy for pancreatic cancer.
The first model (M1) using 56 plans and the second model (M2) using 31 plans were created in the first 7 months of the study. The ratios of volume of both kidneys overlapping the expanded planning target volume to the total volume of both kidneys (V/V) were calculated in all cases to customize M1. Regression lines were derived from V/V and mean dose to both kidneys. The third model (M3) was created using 30 plans which data put them below the regression line. For validation, KBP was performed with the three models on 21 patients.
V of the left kidney for M1 plans was 7.3% greater than for clinical plans. Dmean of the left kidney for M2 plans was 2.2% greater than for clinical plans. There was no significant difference between all kidney doses in M3 and clinical plans. Dmean of the left kidney for M2 plans was 2.2% greater than for clinical plans. Dmean to both kidneys did not differ significantly between the three models in validation plans with V/V lower than average. In plans with larger than average volumes, the Dmean of validation plans created by M3 was significantly lower for both kidneys by 1.7 and 0.9 Gy than with M1 and M2, respectively.
Selecting plans to register in a model by analyzing dosimetry and geometry is an effective means of improving the KBP model.
评估使用剂量学分析定制基于知识的计划（KBP）模型，用于胰腺癌的容积调强弧形放疗。
在研究的前7个月创建了第一个使用56个计划的模型（M1）和第二个使用31个计划的模型（M2）。在所有病例中计算双侧肾脏与扩大的计划靶体积重叠的体积与双侧肾脏总体积的比值（V/V），以定制M1。从V/V和双侧肾脏的平均剂量得出回归线。第三个模型（M3）使用30个数据位于回归线以下的计划创建。为进行验证，对21例患者使用这三个模型进行KBP。
M1计划中左肾的V比临床计划大7.3%。M2计划中左肾Dmean比临床计划大2.2%。M3和临床计划中所有肾脏剂量之间无显著差异。M2计划中左肾Dmean比临床计划大2.2%。在V/V低于平均值的验证计划中，三个模型之间双侧肾脏的Dmean无显著差异。在体积大于平均值的计划中，M3创建的验证计划的双侧肾脏Dmean分别比M1和M2显著低1.7 Gy和 0.9 Gy。
通过分析剂量学和几何学来选择纳入模型的计划是改进KBP模型的有效方法。
