Faculty of Physics, West University of Timisoara, Timisoara, Romania.
MedEuropa, Oradea, 410191, Romania.
Radiat Oncol. 2023 Jul 28;18(1):126. doi: 10.1186/s13014-023-02313-5.
Beam matching is a concept in radiotherapy applied to clinics where more than one linac is employed to harmonise beam characteristics across linacs for allowing patients interchange without replanning. In view of this, the current study analyzes and compares dosimetric characteristics of 6MV flattening filter free and flattened beams of three beam-matched linear accelerators (linacs) from three different clinics with the aim to evaluate the matching under tight criteria for gamma analysis.
Three Elekta linacs from three different clinics were included. The linacs have the same collimator assembly, Elekta Agility. Beam data were collected during commissioning process using PTW dosimetry systems. Dose profiles and percentage depth doses (PDD) were analyzed using 1D gamma analysis (1 mm/1%) as well as the following parameters: depth of maximum dose, PDD10, flatness, unflattnes, symmetry, penumbra, output factors. Additionally, five stereotactic treatment plans were optimized in one clinic and calculated by all three planning systems (Monaco) for a dosimetric comparison.
Gamma analysis of dose profiles and PDDs showed clinically acceptable results of 96.3% passing rate for profiles and 100% passing rate for PDDs. All dosimetric parameters were in good agreement with the reference data. Furthermore, dosimetric comparisons between stereotactic treatment plans showed a maximum standard deviation of 0.48 Gy for the maximum dose to PTV, and a maximum standard deviation of 0.1 Gy for the dose to the organs at risk.
All three linacs showed a strong agreement between parameters and passed the gamma analysis using 1% DD/1mm DTA criteria. This study confirmed the matching between linacs, offering the possibility to interchange patients with no replanning.
在放射治疗中，束流匹配是一个概念，适用于使用多台直线加速器（linac）的临床情况，以便协调 linac 之间的光束特性，实现患者无需重新计划即可互换。有鉴于此，本研究分析和比较了来自三个不同诊所的三台束流匹配直线加速器的 6MV 无均整器自由和平坦光束的剂量学特性，目的是根据严格的伽马分析标准评估匹配情况。
纳入了来自三个不同诊所的三台 Elekta linac。这些 linac 具有相同的准直器组件，即 Elekta Agility。在调试过程中，使用 PTW 剂量测量系统收集光束数据。使用一维伽马分析（1mm/1%）以及以下参数分析剂量分布曲线和百分深度剂量（PDD）：最大剂量深度、PDD10、平坦度、不平整度、对称性、半影、输出因子。此外，在一个诊所中，优化了五个立体定向治疗计划，并由所有三个计划系统（Monaco）进行计算，以进行剂量比较。
剂量分布曲线和 PDD 的伽马分析显示，通过率为 96.3%的临床可接受的结果，PDD 的通过率为 100%。所有剂量学参数与参考数据吻合良好。此外，立体定向治疗计划之间的剂量比较显示，PTV 最大剂量的最大标准偏差为 0.48Gy，危及器官的剂量的最大标准偏差为 0.1Gy。
所有三台 linac 在参数之间表现出很强的一致性，并且通过了使用 1%DD/1mm DTA 标准的伽马分析。本研究证实了 linac 之间的匹配，为无需重新计划即可交换患者提供了可能性。
