Technical Note: Relationships between gamma criteria and action levels: Results of a multicenter audit of gamma agreement index results
Technical Note: Relationships between gamma criteria and action levels: Results of a multicenter audit of gamma agreement index results
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DOI：
10.1118/1.4942488
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发表时间：
2016-03-01
期刊：
影响因子：
3.8
通讯作者：
Kairn, Tanya
中科院分区：
文献类型：
--
作者：
Crowe, Scott B.;Sutherland, Bess;Kairn, Tanya
目的：本研究的目的是对调制放疗质量保证（QA）数据进行多中心审计，以提供伽马评价标准和行动水平选择的实际检查。gamma评估方法用于患者特异性预处理QA的使用是广泛的，大多数商业解决方案都实现了该方法。方法：采用1%/ 1mm， 2%/ 2mm, 2%/ 3mm, 3%/ 2mm， 3%/ 3mm和5%/ 3mm标准计算1265预处理QA测量的Gamma一致性指数，计划在7个治疗中心，使用4种不同的治疗计划系统，使用3种不同的递送系统（调强放疗，体积调制电弧治疗和螺旋断层治疗），并使用3种不同的剂量测量系统进行测量。每对伽玛标准的敏感性相对于使用3%/ 3mm计算的伽玛一致性指数进行评估。结果：在2%/ 2mm， 2%/ 3mm和3%/ 2mm时观察到线性关系。这一结果表明，如果适当调整作用水平，大多数在3%/ 3mm处失效的梁也会失效。一些边缘计划可能通过或失败，这取决于用于剂量差或协议评估距离的相对优先级（更严格的公差）。研究发现，剂量计分辨率和治疗方式对质量保证测量结果的影响小于计算伽马评价的维度数（2D或3D）。结论：这项工作提供了一种方法（和大量的结果样本）来计算不同伽马评价标准的等效作用水平。这项工作为临床决策提供了有价值的指导，也是比较使用不同评价标准的研究中已发表的伽马评价结果的一种手段。更一般地说，这项工作提供的数据支持这样的建议，即在使用伽马评估进行调制放疗QA时，应该选择伽马标准，该标准明确优先考虑解剖部位的每种治疗方式的最重要临床性质。因此，建议将伽马评价作为质量保证分析工具的部门在选择伽马评价标准时，应考虑剂量差和一致距离的相对重要性。(C) 2016年美国医学物理学家协会。
Purpose: The aim of this work was to use a multicenter audit of modulated radiotherapy quality assurance (QA) data to provide a practical examination of gamma evaluation criteria and action level selection. The use of the gamma evaluation method for patient-specific pretreatment QA is widespread, with most commercial solutions implementing the method.Methods: Gamma agreement indices were calculated using the criteria 1%/1 mm, 2%/2 mm, 2%/3 mm, 3%/2 mm, 3%/3 mm, and 5%/3 mm for 1265 pretreatment QA measurements, planned at seven treatment centers, using four different treatment planning systems, delivered using three different delivery systems (intensity-modulated radiation therapy, volumetric-modulated arc therapy, and helical tomotherapy) and measured using three different dose measurement systems. The sensitivity of each pair of gamma criteria was evaluated relative to the gamma agreement indices calculated using 3%/3 mm.Results: A linear relationship was observed for 2%/2 mm, 2%/3 mm, and 3%/2 mm. This result implies that most beams failing at 3%/3 mm would also fail for those criteria, if the action level was adjusted appropriately. Some borderline plans might be passed or failed depending on the relative priority (tighter tolerance) used for dose difference or distance to agreement evaluation. Dosimeter resolution and treatment modality were found to have a smaller effect on the results of QA measurements than the number of dimensions (2D or 3D) over which the gamma evaluation was calculated.Conclusions: This work provides a method (and a large sample of results) for calculating equivalent action levels for different gamma evaluation criteria. This work constitutes a valuable guide for clinical decision making and a means to compare published gamma evaluation results from studies using different evaluation criteria. More generally, the data provided by this work support the recommendation that gamma criteria that specifically prioritize the property of greatest clinical importance for each treatment modality of anatomical site should be selected when using gamma evaluations for modulated radiotherapy QA. It is therefore suggested that departments using the gamma evaluation as a QA analysis tool should consider the relative importance of dose difference and distance to agreement, when selecting gamma evaluation criteria. (C) 2016 American Association of Physicists in Medicine.