Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland.
Accuray Incorporated, Sunnyvale, CA, USA.
Radiat Oncol. 2019 Sep 18;14(1):172. doi: 10.1186/s13014-019-1370-5.
Vendor-independent Monte Carlo (MC) dose calculation (IDC) for patient-specific quality assurance of multi-leaf collimator (MLC) based CyberKnife treatments is used to benchmark and validate the commercial MC dose calculation engine for MLC based treatments built into the CyberKnife treatment planning system (Precision MC).
The benchmark included dose profiles in water in 15 mm depth and depth dose curves of rectangular MLC shaped fields ranging from 7.6 mm × 7.7 mm to 115.0 mm × 100.1 mm, which were compared between IDC, Precision MC and measurements in terms of dose difference and distance to agreement. Dose distributions of three phantom cases and seven clinical lung cases were calculated using both IDC and Precision MC. The lung PTVs ranged from 14 cm to 93 cm. Quantitative comparison of these dose distributions was performed using dose-volume parameters and 3D gamma analysis with 2% global dose difference and 1 mm distance criteria and a global 10% dose threshold. Time to calculate dose distributions was recorded and efficiency was assessed.
Absolute dose profiles in 15 mm depth in water showed agreement between Precision MC and IDC within 3.1% or 1 mm. Depth dose curves agreed within 2.3% / 1 mm. For the phantom and clinical lung cases, mean PTV doses differed from - 1.0 to + 2.3% between IDC and Precision MC and gamma passing rates were > =98.1% for all multiple beam treatment plans. For the lung cases, lung V20 agreed within ±1.5%. Calculation times ranged from 2.2 min (for 39 cm PTV at 1.0 × 1.0 × 2.5 mm native CT resolution) to 8.1 min (93 cm at 1.1 × 1.1 × 1.0 mm), at 2% uncertainty for Precision MC for the 7 examined lung cases and 4-6 h for IDC, which, however, is not optimized for efficiency but used as a gold standard for accuracy.
Both accuracy and efficiency of Precision MC in the context of MLC based planning for the CyberKnife M6 system were benchmarked against MC based IDC framework. Precision MC is used in clinical practice at our institute.
用于多叶准直器（MLC）基于 CyberKnife 治疗的患者特定质量保证的独立于供应商的蒙特卡罗（MC）剂量计算（IDC），用于基准测试和验证内置在 CyberKnife 治疗计划系统（Precision MC）中的用于 MLC 基于治疗的商业 MC 剂量计算引擎。
基准测试包括在 15mm 深度的水中的剂量分布曲线和从 7.6mm×7.7mm 到 115.0mm×100.1mm 的矩形 MLC 形状场的深度剂量曲线，这些曲线在 IDC、Precision MC 和测量之间进行了比较，比较内容包括剂量差异和符合程度。使用 IDC 和 Precision MC 为三个体模病例和七个临床肺病例计算了剂量分布。肺 PTV 的范围从 14cm 到 93cm。使用剂量体积参数和 2%全局剂量差异和 1mm 距离标准以及全局 10%剂量阈值的 3D 伽马分析对这些剂量分布进行了定量比较。记录了计算剂量分布的时间，并评估了效率。
在水中的 15mm 深度处的绝对剂量分布曲线在 Precision MC 和 IDC 之间的一致性在 3.1%或 1mm 以内。深度剂量曲线的一致性在 2.3%/1mm 以内。对于体模和临床肺病例，ID 和 Precision MC 之间的 PTV 平均剂量差异为-1.0%至+2.3%，所有多束治疗计划的伽马通过率均大于等于 98.1%。对于肺病例，肺 V20 的一致性在±1.5%以内。计算时间范围从 2.2 分钟（对于 39cm PTV，在 1.0×1.0×2.5mm 原始 CT 分辨率下）到 8.1 分钟（对于 93cm，在 1.1×1.1×1.0mm 下），对于 Precision MC，对于 7 个检查的肺病例，在 2%的不确定性下，对于 IDC，需要 4-6 小时，但是，这不是为了效率而优化的，而是用作准确性的金标准。
在 CyberKnife M6 系统的 MLC 规划背景下，对 Precision MC 的准确性和效率进行了基准测试，该系统与基于 MC 的 IDC 框架进行了对比。Precision MC 已在我们研究所的临床实践中使用。
