Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, 77030, USA.
Med Phys. 2017 Sep;44(9):4943-4951. doi: 10.1002/mp.12426. Epub 2017 Aug 1.
The Imaging and Radiation Oncology Core Houston (IROC-H) (formerly the Radiological Physics Center) has reported varying levels of agreement in their anthropomorphic phantom audits. There is reason to believe one source of error in this observed disagreement is the accuracy of the dose calculation algorithms and heterogeneity corrections used. To audit this component of the radiotherapy treatment process, an independent dose calculation tool is needed.
Monte Carlo multiple source models for Elekta 6 MV and 10 MV therapeutic x-ray beams were commissioned based on measurement of central axis depth dose data for a 10 × 10 cm field size and dose profiles for a 40 × 40 cm field size. The models were validated against open field measurements consisting of depth dose data and dose profiles for field sizes ranging from 3 × 3 cm to 30 × 30 cm . The models were then benchmarked against measurements in IROC-H's anthropomorphic head and neck and lung phantoms.
Validation results showed 97.9% and 96.8% of depth dose data passed a ±2% Van Dyk criterion for 6 MV and 10 MV models respectively. Dose profile comparisons showed an average agreement using a ±2%/2 mm criterion of 98.0% and 99.0% for 6 MV and 10 MV models respectively. Phantom plan comparisons were evaluated using ±3%/2 mm gamma criterion, and averaged passing rates between Monte Carlo and measurements were 87.4% and 89.9% for 6 MV and 10 MV models respectively.
Accurate multiple source models for Elekta 6 MV and 10 MV x-ray beams have been developed for inclusion in an independent dose calculation tool for use in clinical trial audits.
成像和放射肿瘤学核心休斯顿（IROC-H）（前身为放射物理学中心）在他们的人体模型审计中报告了不同程度的一致性。有理由相信，这种观察到的不一致的一个误差源是所使用的剂量计算算法和不均匀性校正的准确性。为了审核放射治疗过程的这一部分，需要一个独立的剂量计算工具。
根据 10×10cm 射野的中心轴深度剂量数据和 40×40cm 射野的剂量分布，为 Elekta 6MV 和 10MV 治疗 X 射线束开发了蒙特卡罗多源模型。该模型基于对 Elekta 6MV 和 10MV 治疗 X 射线束的中央轴深度剂量数据和剂量分布的测量进行验证。模型还针对 3×3cm 至 30×30cm 射野的开放场测量进行了验证。然后，将模型与 IROC-H 的人体头颈部和肺部模型进行了基准测试。
验证结果表明，6MV 和 10MV 模型的深度剂量数据分别有 97.9%和 96.8%通过了±2%Van Dyk 准则。剂量分布比较显示，使用±2%/2mm 准则，6MV 和 10MV 模型的平均符合率分别为 98.0%和 99.0%。使用±3%/2mm 伽玛准则评估了体模计划比较，蒙特卡罗和测量之间的平均通过率分别为 6MV 和 10MV 模型的 87.4%和 89.9%。
为 Elekta 6MV 和 10MV X 射线束开发了准确的多源模型，以纳入独立的剂量计算工具，用于临床试验审核。
