PDF(Pubmed)
Abstract：
OBJECTIVE: Single-isocenter multi-target intracranial stereotactic radiotherapy (SIMT) is an effective treatment for brain metastases with complex treatment plans and delivery optimization necessitating rigorous quality assurance. This work aims to assess five methods for quality assurance of SIMT treatment plans in terms of their suitability and sensitivity to delivery errors.
METHODS: Sun Nuclear ArcCHECK and SRS MapCHECK, GafChromic EBT Radiochromic Film, machine log files, and Varian Portal Dosimetry were all used to measure 15 variations of a single SIMT plan. Variations of the original plan were created with Python. They comprised various degrees of systematic MLC offsets per leaf up to 2 mm, random per-leaf variations with differing minimum and maximum magnitudes, simulated collimator, and dose miscalibrations (MU scaling). The erroneous plans were re-imported into Eclipse and plan-quality degradation was assessed by comparing each plan variation to the original clinical plan in terms of the percentage of clinical goals passing relative to the original plan. Each erroneous plan could be then ranked by the plan-quality degradation percentage following recalculation in the TPS so that the effects of each variation could be correlated with γ pass rates and detector suitability.
CONCLUSIONS: It was found that 2%/1 mm is a good starting point for the ArcCHECK, Portal Dosimetry, and the SRS MapCHECK methods, respectively, and provides clinically relevant error detection sensitivity. Looser dose criteria of 5%/1 mm or 5%/1.5 mm are suitable for film dosimetry and log-file-based methods. The statistical methods explored can be expanded to other areas of patient-specific QA and detector assessment.
METHODS: Sun Nuclear ArcCHECK and SRS MapCHECK, GafChromic EBT Radiochromic Film, machine log files, and Varian Portal Dosimetry were all used to measure 15 variations of a single SIMT plan. Variations of the original plan were created with Python. They comprised various degrees of systematic MLC offsets per leaf up to 2 mm, random per-leaf variations with differing minimum and maximum magnitudes, simulated collimator, and dose miscalibrations (MU scaling). The erroneous plans were re-imported into Eclipse and plan-quality degradation was assessed by comparing each plan variation to the original clinical plan in terms of the percentage of clinical goals passing relative to the original plan. Each erroneous plan could be then ranked by the plan-quality degradation percentage following recalculation in the TPS so that the effects of each variation could be correlated with γ pass rates and detector suitability.
CONCLUSIONS: It was found that 2%/1 mm is a good starting point for the ArcCHECK, Portal Dosimetry, and the SRS MapCHECK methods, respectively, and provides clinically relevant error detection sensitivity. Looser dose criteria of 5%/1 mm or 5%/1.5 mm are suitable for film dosimetry and log-file-based methods. The statistical methods explored can be expanded to other areas of patient-specific QA and detector assessment.
摘要：
目的：单等中心多靶点颅内立体定向放射治疗（SIMT）是一种治疗脑转移瘤的有效方法，治疗方案复杂，给药优化需要严格的质量保证。这项工作旨在评估5种方法，以确保SIMT治疗计划的适用性和对交付错误的敏感性。
方法：SunNuclearArcCHECK和SRSMapCHECK，GafChromicEBT放射变色薄膜，机器日志文件,和VarianPortal剂量测定均用于测量单个SIMT计划的15种变化。原始计划的变体是用Python创建的。它们包括不同程度的系统MLC偏移，每片叶子高达2毫米，具有不同最小和最大值的随机每叶变化，模拟准直器，和剂量校准错误（MU缩放）。将错误的计划重新输入到Eclipse中，并通过将每个计划变化与原始临床计划进行比较，以相对于原始计划通过的临床目标的百分比来评估计划质量下降。然后,在TPS中重新计算之后,可以通过计划质量劣化百分比对每个错误计划进行排序,使得每个变化的影响可以与γ通过率和检测器适合性相关。
结论：发现2％/1毫米是ArcCHECK的良好起点，门户剂量测定,和SRSMapCHECK方法，分别,并提供临床相关的错误检测灵敏度。5%/1mm或5%/1.5mm的较宽松剂量标准适用于胶片剂量测定和基于日志文件的方法。所探索的统计方法可以扩展到患者特异性QA和检测器评估的其他领域。
方法：SunNuclearArcCHECK和SRSMapCHECK，GafChromicEBT放射变色薄膜，机器日志文件,和VarianPortal剂量测定均用于测量单个SIMT计划的15种变化。原始计划的变体是用Python创建的。它们包括不同程度的系统MLC偏移，每片叶子高达2毫米，具有不同最小和最大值的随机每叶变化，模拟准直器，和剂量校准错误（MU缩放）。将错误的计划重新输入到Eclipse中，并通过将每个计划变化与原始临床计划进行比较，以相对于原始计划通过的临床目标的百分比来评估计划质量下降。然后,在TPS中重新计算之后,可以通过计划质量劣化百分比对每个错误计划进行排序,使得每个变化的影响可以与γ通过率和检测器适合性相关。
结论：发现2％/1毫米是ArcCHECK的良好起点，门户剂量测定,和SRSMapCHECK方法，分别,并提供临床相关的错误检测灵敏度。5%/1mm或5%/1.5mm的较宽松剂量标准适用于胶片剂量测定和基于日志文件的方法。所探索的统计方法可以扩展到患者特异性QA和检测器评估的其他领域。
