Universitätsklinikum Schleswig-Holstein, Klinik für Strahlentherapie, Kiel, Germany.
Department of Clinical Oncology, Tuen Mun Hospital, Hong Kong Special Administrative Region of China, People's Republic of China.
Phys Med Biol. 2019 Feb 11;64(4):045009. doi: 10.1088/1361-6560/aafd47.
In radiosurgery (SRS), the geometric uncertainties of machine-related delivery including image-guidance and hence the planning target volume (PTV) are often evaluated by the end-to-end gamma (γ) comparison that carries no information about the clinical relevance of deviations of individual SRS plans during delivery quality assurance (DQA). A proof-of-concept method was proposed to derive the PTV against both the plan- and the machine-specific delivery errors directly from the clinically relevant dose-volume histograms (DVHs) using measured-guided dose reconstruction (MGDR) during DQA. A liquid-filled detector array and a rotating phantom were used to measure sixteen arc-based radiosurgery treatments with 1 and 2 mm gross tumor volume (GTV)-to-PTV margins, producing MGDR-3D dose distribution on both the phantom and the patient CT for γ index and clinical DVH evaluations, respectively. The PTV was considered optimal when the MGDR showed the desired prescription dose coverage (V ) of the GTV (100% in this study). Associations of the binary V outcomes (<or =100%) of the GTV with the acceptance level of percent γ pass rate (γPR%) at 90 versus 95% were assessed. Further receiver operator characteristic (ROC) analysis was performed to assess the distance-to-agreement (DTA) and local dose difference (ΔD) criteria that may be suitable for treatment acceptance. From the MGDR, 100% GTV V was achieved in 68.8% and 100% of plans with 1 and 2 mm PTV, respectively. V outcomes were neither associated with γPR% at 1-2 mm DTA and 1%-3% ΔD nor the acceptance level for MGDR in the patient CT. ROC analysis shows statistically significant AUC values from 0.78-0.84 and 0.79-0.80 for MGDR phantom and patient doses, respectively. DQA by MGDR-DVH objectives offers the unique opportunity of direct assessment of the dose delivery accuracy and hence the optimal PTV without subject to the statistical correlation between γPR% and clinical metrics. Based on multi-criteria DVH objectives, clinical decision can be instantly made to adjust the treatment plan prescription.
在放射外科治疗（SRS）中，机器相关传输的几何不确定性，包括图像引导，因此规划靶区（PTV），通常通过端到端伽马（γ）比较进行评估，该比较没有提供传输质量保证（DQA）期间个别 SRS 计划偏差的临床相关性信息。提出了一种概念验证方法，使用 DQA 期间的测量引导剂量重建（MGDR），直接从临床相关剂量-体积直方图（DVH）中得出针对计划和机器特定传输误差的 PTV。使用液体填充探测器阵列和旋转体模测量了十六个基于弧的放射外科治疗，其中 GTV 到 PTV 的边界为 1 和 2mm，在体模和患者 CT 上分别使用 MGDR-3D 剂量分布进行γ指数和临床 DVH 评估。当 MGDR 显示 GTV 的所需处方剂量覆盖（V ）（本研究中为 100%）时，认为 PTV 是最佳的。评估了 GTV 的二元 V 结果（<或=100%）与 90%与 95%γ通过率（γPR%）接受水平之间的关联。进一步进行了接收器操作特性（ROC）分析，以评估可能适合治疗接受的距离一致（DTA）和局部剂量差异（ΔD）标准。从 MGDR 来看，分别有 68.8%和 100%的 1mm 和 2mm PTV 计划实现了 100%的 GTV V 。V 结果与 1-2mm DTA 和 1%-3%ΔD 处的γPR%以及患者 CT 中 MGDR 的接受水平均无关联。ROC 分析显示，MGDR 体模和患者剂量的 AUC 值分别为 0.78-0.84 和 0.79-0.80，具有统计学意义。基于多标准 DVH 目标的 DQA 提供了直接评估剂量传输准确性的独特机会，因此无需考虑γPR%与临床指标之间的统计相关性。基于多标准 DVH 目标，可以立即做出临床决策来调整治疗计划处方。
