School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, India.
MVR Cancer Centre and Research Institute, Kozhikode 693601, India.
Asian Pac J Cancer Prev. 2024 Sep 1;25(9):3283-3291. doi: 10.31557/APJCP.2024.25.9.3283.
Our study aimed to establish a standardized methodology for selecting "reference" and "evaluated" distributions in gamma analysis for Monte Carlo (MC) based intensity modulated treatment plans. Evaluation of importance of reference selection in MC based and non MC based treatment planning systems were analysed using a study classification.
Three categories were utilized to analyzed gamma passing rates across using different treatment planning systems (TPS) and detectors for thirty five patients. Category 1 utilized MC-based Monaco TPS plans and a 2 dimensional(2D) I'mRTMatriXX detector. Category 2 employed non-MC-based Eclipse TPS plans, assessed with a 2D I'mRTMatriXX detector. In Category 3, MC-based Monaco TPS plans were validated using a Dolphin detector. All plans were subjected to analysis using gamma criteria, which considered a dose difference of 3% and a distance to agreement of 3mm. Additionally, another set of gamma criteria was employed, with a dose difference of 3% and a distance to agreement of 2mm. An introduced Asymmetric factors in both 2D and 3D analysis will quantify the asymmetric nature of gamma based on the choice of "reference" distribution.
For 2D Gamma analysis, MC-based Monaco TPS and I'mRTMatriXX showed a consistent positive Zk2D trend for all patients, with significant p-values below 0.01 for both gamma passing criteria. In contrast, non-MC based Eclipse TPS exhibited varied Zk2D results, with non-significant p-values. In 3D Gamma analysis, all patients exhibited positive Zk3D values with significant p-values below 0.01 when "references" were swapped. The Pearson correlation between asymmetricity and isodose volumes was notably high at 0.99 for both gamma criteria.
Our study highlights the imperative of using MC-based TPS as the definitive "reference" in gamma analysis for patient specific quality assurance of intensity modulated radiation therapy, emphasizing that variations can mislead results, especially given gamma analysis's sensitivity to MC calculation noise.
本研究旨在为蒙特卡罗（MC）基强度调制治疗计划的伽马分析建立一种标准化的选择“参考”和“评估”分布的方法。通过研究分类分析了 MC 基和非 MC 基治疗计划系统中参考选择的重要性。
使用三种分类方法对 35 名患者的不同治疗计划系统（TPS）和探测器的伽马通过率进行分析。第 1 类使用 MC 基 Monaco TPS 计划和二维（2D）I'mRTMatriXX 探测器。第 2 类采用非 MC 基 Eclipse TPS 计划，使用 2D I'mRTMatriXX 探测器进行评估。第 3 类，使用 Dolphin 探测器验证 MC 基 Monaco TPS 计划。所有计划均使用伽马标准进行分析，考虑剂量差为 3%，协议距离为 3mm。此外，还使用了另一组伽马标准，剂量差为 3%，协议距离为 2mm。在 2D 和 3D 分析中引入的不对称因子将根据“参考”分布的选择量化伽马的不对称性。
对于 2D 伽马分析，MC 基 Monaco TPS 和 I'mRTMatriXX 对所有患者均显示出一致的正 Zk2D 趋势，两种伽马通过率标准的 p 值均小于 0.01。相比之下，非 MC 基 Eclipse TPS 显示出不同的 Zk2D 结果，p 值无统计学意义。在 3D 伽马分析中，当“参考”互换时，所有患者均显示出正 Zk3D 值，p 值均小于 0.01。两种伽马标准下，不对称性与等剂量体积之间的 Pearson 相关性均显著，高达 0.99。
本研究强调了在强度调制放射治疗的患者特定质量保证的伽马分析中使用 MC 基 TPS 作为确定“参考”的重要性，表明变化可能会误导结果，特别是考虑到伽马分析对 MC 计算噪声的敏感性。
